Thisol's TUL is Julie Townsend, and she's a little distracted. She's trying to finalize her (re-)enrollment at Stanford, where she's getting her Ph.D. She's somehow finagled a deal where she'll basically do her regular job here at JPL and get a Ph.D. for it.
Damn, I didn't even know we could do that.
Today is the first time we're trying to plan three sols at once. It's a Friday, and the idea is that we'll plan the entire weekend today -- sols 259, 260, and 261 -- and return Monday. As far as the RPs are concerned, we have two sols to plan: on 259, we do a little IDD work, and on 261, we stow and bump backward uphill.
The uphill bump is the tricky part. We drove down to Conjunction Junction with a specific plan, part of a never-to-be-repeated (well, probably) wind experiment. Before conjunction, we imaged this area, then drove onto it, and the remaining part of the plan is to back out the way we came in and image it again.
As always with these vehicles, the hitch is that distance is easy but precision is hard. And this drive is all about precision. The images will be taken immediately following the drive, which means we have to choose the image pointing now, without knowing exactly where the rover will actually end up. To make life just a little more complicated, we need to get the rover back to the same spot as the pre-conjunction imaging, to make it easier to compare the images. Chris has already done the drive -- it's a simple one, just a straight backup -- but he hasn't allowed enough for slippage.
When coming downhill, we slipped farther than we'd expected -- about 45cm on a 1.5cm drive, giving 30% slip. I tell this to Chris, and he makes a face. "Thirty percent slip -- on this terrain?" he says.
"I was surprised, too," I shrug. "We were expecting about 10%, maybe 20% in the worst case. But both Rich Petras and I came up with the same number." I show him the result in the HAZCAM mesh in RSVP; when you model the rover driving 30% too far, the result in the front HAZCAM mesh looks almost exactly like the actual post-drive mesh.
Chris frowns again. "We shouldn't have slipped that much," he muses. He thinks for a minute. During conjunction, we got NAVCAM images from our new position. It should be possible to compare these with pre-drive NAVCAM images, which would give us a better slip estimate. Chris does this, and what do you know -- according to his results, we actually slipped only about 7%.
Good rover. Good girl.
But what the heck is up with that? Rich Petras isn't around, so we can't ask him how he did his analysis, but we realize that he must have based it on the HAZCAMs, since that's all we had at the time. The RSVP-based analysis I did is also ultimately based on the HAZCAMs, for the same reason. And since the HAZCAMs give less precise ranges, we postulate that the HAZCAMs just misled us.
We might be doing the wrong thing, but the smart gamble is to trust the NAVCAMs. So we do that.
Not for the first time, I marvel over the amount of blood, sweat, and tears that we sometimes shed over a matter of centimeters. Here, we sweated for an hour over a matter of maybe 20cm or so -- less than 8 inches. But when that 8 inches could determine whether we manage to nail a one-of-a-kind scientific experiment, well ....
So Chris's skepticism probably saved the experiment. But I have him beat: he saved the day only once, but I manage to save the day twice. I am on the ball.
The first one is definitely a case of Murphy's Law in action. Early in the mission, I wrote a flight-rule checking script, called fr_check, to help us RPs avoid dumb mistakes. One of the rules it enforces is this: we're supposed to open the MI's dust cover exactly when we're going to take an image. We should open the dust cover, take an image -- or a series of them -- and then close the dust cover again. On rare occasions, we deliberately take images with the dust cover closed.[1] (The dust cover is not opaque but a translucent orangish material; cover-closed images are poorer quality, but are helpful in making false-color products.)
Since fr_check can't tell whether we're taking a cover-closed image on purpose, this rule turned out to be a little "chatty," too eager to warn about cases where in fact everything was OK. Warning too frequently can be just as dangerous as not warning at all, since it can lead you to ignore actual problems, so one of the other RPs recently asked me to dial it down a little.
And sure enough, thisol -- the first MI-using sol after I made the change -- the change caused fr_check to fail to warn about an actual problem. Thisol's MI work is a little unusual -- normally, we take a series of images at different distances from the target, but because we're so downlink-constrained thisol, we just took a single image. And we forgot to open the dust cover. Since there was just one image, the amount of MI work fell under the rule's new threshold, and it decided to keep its mouth shut.
Luckily, I catch this manually and add the appropriate commands to open and close the dust cover. (It ends up returning an absolutely perfect image.)
I save another science observation as well. Originally, it was our practice to call instrument-on and instrument-off sequences in the RP sequences. For instance, we'd place an instrument such as the MB and call the sequence that turned it on; later, we'd turn the first instrument off when switching to another instrument. For various reasons, we don't consistently do this any more, so it's reasonably common to have an IDD sequence that doesn't turn on the instrument it places. Instead, the master sequence -- the day's backbone -- will start or stop the instrument at the appropriate time.[2]
But today, after reviewing the master and IDD sequences, I realize something is missing. "Hey, did I miss it," I ask, "or did we not turn on the Moessbauer?"
Nope. We did not.
"That would have been embarrassing," I say wryly. One trivial change later, and I've saved a twelve-hour science experiment.
So even though planning three sols keeps us here late, I'm in a good mood. I always am, when I know I've earned the paycheck.
[Next post: sol 265, October 1.]
Footnotes:
[1] Sadly, on both vehicles, the dust cover has now accumulated so much dust that it is opaque. Better the dust cover than the lens itself, though.
[2] Now we always do it that way. It's easier to make sure you're getting something right when you do it the same way all the time.
2009-09-24
2009-09-23
Spirit Sol 258
Mars is once more visible from Earth. And we rover planners are back to work.
Thisol's sequence is mostly cut and pasted from previous sols: we're once again taking MI images of the capture and filter magnets (though not as many as we usually do when we do this, since we're downlink-limited thisol), taking another image of the dirt clod stuck to the MB, redoing the MI mosaic over GreenEyes, and finally APXSing the hole we left behind when we pulled up the dirt clod.
The only thing complicated about the sol is putting the APXS on the dirt clod's former home. Normally, we have a terrain mesh that shows our targets, but that's not the case here -- this time, we have only the MI images to go on.
This ought to be easy: we know where we placed the IDD previously, and we can see exactly where the missing soil is relative to that placement. (The MB contact ring, which made the impression, is an O-shape. The resulting impression is a rough semicircle, centered "northwest" of the center of the images). The problem is that I'm not sure of the dimensions of the contact ring, so although I know which direction I want to move the IDD, I'm not sure how far to move it. The documentation I normally use to answer questions like this doesn't tell me, so I start looking around for someone who would know.
This proves to be harder than I expected. The Mobility/IDD guys on shift don't know. Jake Matijevic points me to a book of images, which shows the part I'm interested in but doesn't show scale. Lori Shirashi isn't around, so I call Joe Melko, who doesn't provide an answer.
At last I try asking thisol's MB instrument rep, Iris. She proves to know just enough: she knows the inner diameter of the O. Armed with this, I'm able to go back to the image Jake pointed me to, measure carefully with the ruler built into my trusty Swiss Army knife, and work out the width of the ring itself. (For the record: the inner diameter is 15mm, the ring itself is 10mm wide.)
Which means, since I want to move the arm to the middle of the ring's impression, that I need to move it: 12mm. Thank you, and good night.
Courtesy NASA/JPL-Caltech. An MI of the filter magnet, showing -- yup -- we plopped a chunk of dirt right onto it.
Courtesy NASA/JPL-Caltech. The capture magnet, which we also imaged thisol. I love that manadala-like bullseye pattern.
Thisol's sequence is mostly cut and pasted from previous sols: we're once again taking MI images of the capture and filter magnets (though not as many as we usually do when we do this, since we're downlink-limited thisol), taking another image of the dirt clod stuck to the MB, redoing the MI mosaic over GreenEyes, and finally APXSing the hole we left behind when we pulled up the dirt clod.
The only thing complicated about the sol is putting the APXS on the dirt clod's former home. Normally, we have a terrain mesh that shows our targets, but that's not the case here -- this time, we have only the MI images to go on.
This ought to be easy: we know where we placed the IDD previously, and we can see exactly where the missing soil is relative to that placement. (The MB contact ring, which made the impression, is an O-shape. The resulting impression is a rough semicircle, centered "northwest" of the center of the images). The problem is that I'm not sure of the dimensions of the contact ring, so although I know which direction I want to move the IDD, I'm not sure how far to move it. The documentation I normally use to answer questions like this doesn't tell me, so I start looking around for someone who would know.
This proves to be harder than I expected. The Mobility/IDD guys on shift don't know. Jake Matijevic points me to a book of images, which shows the part I'm interested in but doesn't show scale. Lori Shirashi isn't around, so I call Joe Melko, who doesn't provide an answer.
At last I try asking thisol's MB instrument rep, Iris. She proves to know just enough: she knows the inner diameter of the O. Armed with this, I'm able to go back to the image Jake pointed me to, measure carefully with the ruler built into my trusty Swiss Army knife, and work out the width of the ring itself. (For the record: the inner diameter is 15mm, the ring itself is 10mm wide.)
Which means, since I want to move the arm to the middle of the ring's impression, that I need to move it: 12mm. Thank you, and good night.
Courtesy NASA/JPL-Caltech. An MI of the filter magnet, showing -- yup -- we plopped a chunk of dirt right onto it.
Courtesy NASA/JPL-Caltech. The capture magnet, which we also imaged thisol. I love that manadala-like bullseye pattern.
2009-09-06
Spirit Sol 241
If all goes well, I don't have a job. For the next ten days or so, that is -- we won't be driving the rover or moving the IDD during conjunction, so I can spend the time on other projects.
If all goes well. Which, again, we won't know until toward the end of the SOWG. But the plan is that there won't be anything for me to do -- and, indeed, the confirming NAVCAMs of the last IDD placement arrive on schedule, and the IDD is right where it's supposed to be. I flip back and forth through the images, and everything just looks like it went perfectly.
Luckily, there are sharper eyes than mine looking at these images. Rich Petras spots a dark clump on the MB, one that's not supposed to be there. When we look more closely at the images, we discover that the MB picked up some dirt when we used it to touch the soil. (The MIs also clearly show this dirt missing from the soil patch itself.) From that point on, each image that shows the MB shows the chunk of dirt riding along with it, hanging off the outside of the contact ring.
Including -- uh-oh. Including the image we took just before placing the MB on the filter magnet. Which means we just put a whole bunch of dirt onto the magnet.
It's unlikely this will be a major problem. Probably, the worst case would be that when we placed the MB on the magnet, the closing contact ring squished the dirt into the MB's own field of view. If indeed this happened, they'll likely be able to recalibrate the MB to subtract out the dirt's effect. And maybe we'll find a way to shake it off, or scrape it off, if it doesn't look like it'll fall off by itself.
I ask the scientists whether they want us to do anything about this nextersol -- maybe we could retract the MB, image it to see if the soil's still there, check out the magnets, whatever. But they decide against it. I've put the arm where they want it to be right now, and they don't want to risk that. They'll want to inspect the MB and the filter magnet more thoroughly, but they want to wait until after conjunction to do it.
So that means no IDD work nextersol -- nor, indeed, through conjunction -- and therefore nothing for me to do.
Well, I guess there is one thing to do -- we need to start laying out a long-term post-conjunction drive plan. The next science goal is to reach Pergamon Ridge, about 75m east from Conjunction Junction. It's pretty easy to plan this path; there's no good way to get there from here, but Ray and Bethany and I look at the insolation maps and decide we'll head to the northeast. As we go, we'll keep taking pictures of Pergamon Ridge. If a path opens up, we'll take it; otherwise, we'll have to treat Pergamon Ridge as unreachable.
And that's it. I wish everyone a Happy Conjunction, and go home.
[Next post: sol 258, September 23. Sorry about the long delay; that's what happens when a gigantic ongoing multi-billion-year-old nuclear explosion floats between you and something you want to send radio signals to.
Most of us spent these two weeks catching up on other work, or taking vacations. I did some of the former, but used about half the time to write an ops tool that had been sitting in my head for months.
I called it "mPhoto," and it was conceived as a sort of "iPhoto for MER." The idea was to quickly render a simple grid showing thumbnails of all of the recent images, enabling the user to rapidly zero in on images of interest. In addition, it provided some very simple image-manipulation facilities, and the ability to save the images in more useful formats than the one the project normally uses internally. Partly, I wanted the tool itself, and partly I wanted a chance to experiment with writing software in a different -- frankly, a somewhat sloppier -- way than I normally do.
It didn't come out perfect, but I was very happy with it, given that I explicitly gave myself a time limit of one week to develop the entire thing. Despite its limitations and lack of polish, it still does some things better than any other image-browsing tool on the project, so that even now it's still used by me and others. It scratched my itch, and I had fun making it.]
Courtesy NASA/JPL-Caltech. One of the NAVCAM images showing the chunk of dirt that stuck to the MB, shortly before the sequence would put the MB on the rover's magnets. You can see the chunk of dirt on the MB contact ring, near the top of the image.
Courtesy NASA/JPL-Caltech. Sure enough, the MI images -- like this one -- show a chunk of dirt got torn out of the soil where the MB contacted it.
If all goes well. Which, again, we won't know until toward the end of the SOWG. But the plan is that there won't be anything for me to do -- and, indeed, the confirming NAVCAMs of the last IDD placement arrive on schedule, and the IDD is right where it's supposed to be. I flip back and forth through the images, and everything just looks like it went perfectly.
Luckily, there are sharper eyes than mine looking at these images. Rich Petras spots a dark clump on the MB, one that's not supposed to be there. When we look more closely at the images, we discover that the MB picked up some dirt when we used it to touch the soil. (The MIs also clearly show this dirt missing from the soil patch itself.) From that point on, each image that shows the MB shows the chunk of dirt riding along with it, hanging off the outside of the contact ring.
Including -- uh-oh. Including the image we took just before placing the MB on the filter magnet. Which means we just put a whole bunch of dirt onto the magnet.
It's unlikely this will be a major problem. Probably, the worst case would be that when we placed the MB on the magnet, the closing contact ring squished the dirt into the MB's own field of view. If indeed this happened, they'll likely be able to recalibrate the MB to subtract out the dirt's effect. And maybe we'll find a way to shake it off, or scrape it off, if it doesn't look like it'll fall off by itself.
I ask the scientists whether they want us to do anything about this nextersol -- maybe we could retract the MB, image it to see if the soil's still there, check out the magnets, whatever. But they decide against it. I've put the arm where they want it to be right now, and they don't want to risk that. They'll want to inspect the MB and the filter magnet more thoroughly, but they want to wait until after conjunction to do it.
So that means no IDD work nextersol -- nor, indeed, through conjunction -- and therefore nothing for me to do.
Well, I guess there is one thing to do -- we need to start laying out a long-term post-conjunction drive plan. The next science goal is to reach Pergamon Ridge, about 75m east from Conjunction Junction. It's pretty easy to plan this path; there's no good way to get there from here, but Ray and Bethany and I look at the insolation maps and decide we'll head to the northeast. As we go, we'll keep taking pictures of Pergamon Ridge. If a path opens up, we'll take it; otherwise, we'll have to treat Pergamon Ridge as unreachable.
And that's it. I wish everyone a Happy Conjunction, and go home.
[Next post: sol 258, September 23. Sorry about the long delay; that's what happens when a gigantic ongoing multi-billion-year-old nuclear explosion floats between you and something you want to send radio signals to.
Most of us spent these two weeks catching up on other work, or taking vacations. I did some of the former, but used about half the time to write an ops tool that had been sitting in my head for months.
I called it "mPhoto," and it was conceived as a sort of "iPhoto for MER." The idea was to quickly render a simple grid showing thumbnails of all of the recent images, enabling the user to rapidly zero in on images of interest. In addition, it provided some very simple image-manipulation facilities, and the ability to save the images in more useful formats than the one the project normally uses internally. Partly, I wanted the tool itself, and partly I wanted a chance to experiment with writing software in a different -- frankly, a somewhat sloppier -- way than I normally do.
It didn't come out perfect, but I was very happy with it, given that I explicitly gave myself a time limit of one week to develop the entire thing. Despite its limitations and lack of polish, it still does some things better than any other image-browsing tool on the project, so that even now it's still used by me and others. It scratched my itch, and I had fun making it.]
Courtesy NASA/JPL-Caltech. One of the NAVCAM images showing the chunk of dirt that stuck to the MB, shortly before the sequence would put the MB on the rover's magnets. You can see the chunk of dirt on the MB contact ring, near the top of the image.
Courtesy NASA/JPL-Caltech. Sure enough, the MI images -- like this one -- show a chunk of dirt got torn out of the soil where the MB contacted it.
2009-09-05
Spirit Sol 240
Our email problems and the attendant scheduling problems continue, but it seems to be getting better. I arrive an hour early -- thinking I'd be only half an hour early, but the schedule started later than I thought. No problem. Early is no problem.
The day is ambitious. In the morning we MB-touch the soil and start a short APXS integration. After that, the fun begins: we'll do a 2x2 mosaic of MI stacks around the chosen target, hold the RAT out where the PANCAM can image its magnets, then MI the capture and filter magnets (which are located on the rover body, at the base of the mast). Last, we'll place the MB on the filter magnet.
As on previous sols, we're planning in the blind here; the downlink doesn't start until the SOWG meeting is nearly over. When we get the images, I'm at first satisfied -- then concerned. (Then ... kind of sleepy ... no, wait. Leave it at concerned.) Something looks wrong with the final front HAZCAM, and after a minute I realize what's bothering me. It's too level.
We wanted to end this drive with a better insolation (solar tilt). Stopped on the slope, with the solar panels aimed at the sun, would be good. Level is bad. It's hard to tell, but the picture looks level.
Oh, shit.
This means we're going to have to scrap the planned IDD work for the sol and hope we can work out a backward drive upslope -- and hope like hell that that drive works.
But before I panic, I check the image headers and do a little math. Our roll is -11.6 degrees, pitch -7.0 degrees, making our overall tilt about 13.5 degrees. RSVP's predictions varied depending on which terrain mesh you used, but it tended to show more like 20 degrees. So this looks bad.
What the hell happened? I ignore the remainder of the meeting, load yestersol's sequence into RSVP and simulate it. Like yestersol, I look at 10% slip (15cm) and 20% slip (30cm). Then I do something I should have done yestersol: I consider worse slips. At 33% slip (45cm) the predicted HAZCAM in RSVP comes out looking almost identical to the actual we just received.
So now we know what went wrong. It was exactly what I was worrying about during the CAM: we slipped more than expected, to the point where we started to level out.
I think hard for a minute about how I want to handle this. As the SOWG meeting breaks up, I activate my mike and tell Ray we might have a problem.
"We don't know that we have one," I tell him, "we'll have to do some more analysis first. But I wanted to let you know we might have to replan the sol to drive instead."
To my surprise, Ray sounds unconcerned. "Okay," he says calmly, "you guys figure it out and we'll do what we need to do."
First I go talk to Rich Petras, the Mobility/IDD guy on duty today. He agrees with me about the slip results (foo!) but doesn't know how to compute the insolation factor from tilt. Neither does our ACS guy, though he's able to show me what the rover will look like as seen from the sun. It looks good, good enough to start me thinking that we might be able to stay put after all. Then again, I don't have a sense of how good it needed to look. On a scale of 0.0 to 1.0, we needed to be about 0.88. Yestersol, we were at about 0.91; if we worsened at all, the rover will survive but we'll feel like dumbasses (that is, I'll feel like a dumbass). We were hoping for something like 0.94 or 0.95. And I can't visually distinguish an attitude that would lead to 0.88 insolation from one that would lead to 0.95 insolation. We need math.
Chris is thisol's floater, and he's in the sequencing MSA when I
return.
"I think we might not need to drive, so I want to get started on the IDD stuff," I tell him. "Can you figure out what our insolation is?"
"Already working on it," he says. He's slinging Perl to get us an approximation.
So he works on that, and I work on the IDD stuff. The script, when he finishes it, reports about a 0.89 or 0.90 insolation, which would be a dropoff from yestersol but good enough that we don't have to move. But only a minute or so after he finishes, Leo Bister comes in with the official word: we're over 0.93. Not only are we good enough, we improved. Not as much of an improvement as we'd hoped, but an improvement all the same.
There's also good news about my IDD sequencing. It's all going smoothly, almost suspiciously smoothly. The scientists have picked a their soil target -- Uxmal, a nice spot right in front of us. When I plug Uxmal into the sequence and run a simulation in RSVP, it works the first time. This is uncommon enough that I go back and check it, but, yes, it really is going to work.
I'm more or less done with the sequence and starting to do the detail work, when Bethany comes in with a request. They've just taken a close look at the PANCAM and there's a perfect patch of soil just by the right front wheel, which is a region that's generally awkward to IDD in. (As it happens, this spot would have been smack in front of us -- in ideal IDD territory -- if we hadn't slipped.)
"Can you get to it?" she asks.
Well, what the hell, I'm game. Everything else seems to be going my way today. She reads off the new target's coordinates and surface normal; I tell RSVP about it, tell the sequence to go there instead of to Uxmal, and simulate it. I'm all prepared for RSVP to spew errors that will take me hours of work to clean up, but nothing doing: like Uxmal, the new target works perfectly the first time.
I'm on a roll, baby.
I have a lot of little details left to attend to, and I even find time for polishing the sequences some. I love it when I find a way to shave a few seconds out of the sequence, to make it just that little bit more elegant -- not only for its own sake, but also because every second we save, every Watt-minute we can squeeze out of the engineering side, we can spend on science. And that's what we're here for, after all.
One of the reasons I have all this time is that, well, let's face it, I'm awesome. But another reason is that there are problems elsewhere in the plan that, like yestersol, slow us down significantly. Once again, we run hours late. Kevin says, "I thought yestersol was the suckiest sol ever. I was wrong. This sol is the suckiest sol ever."
I'm okay with it. My stuff's long since done and I'm ready for conjunction, but more importantly -- much more importantly -- I got a chance to do something I'd been hoping for since the beginning of the mission.
Most of the targets and features we encounter are named by the science team. Every once in a while, the rover drivers get to name something -- I've gotten to do it once or twice -- but it's not common. It's very cool to name something on another planet. The names aren't official, but they do tend to stick; and as when we RAT something, there's a sense of permanence to it.
Since the beginning of the mission, I've been hoping to name something in honor of Jake, since he died only a couple of months before we landed. It didn't seem like the right time when I had the other chances. This one felt right. I don't know why; maybe it's because I've been thinking about him lately, since we moved. Maybe it's some other reason.
Anyway, it fell to me to name the target we abandoned Uxmal for. The tiny little patch of soil our rover will be protecting from the wind throughout the long night of conjunction has a name: "GreenEyes." I miss you, buddy.[1]
Courtesy NASA/JPL-Caltech. The front HAZCAM, showing terrain that's more level than we'd hoped. Aw, crud.
Footnotes:
[1] I still do.
The day is ambitious. In the morning we MB-touch the soil and start a short APXS integration. After that, the fun begins: we'll do a 2x2 mosaic of MI stacks around the chosen target, hold the RAT out where the PANCAM can image its magnets, then MI the capture and filter magnets (which are located on the rover body, at the base of the mast). Last, we'll place the MB on the filter magnet.
As on previous sols, we're planning in the blind here; the downlink doesn't start until the SOWG meeting is nearly over. When we get the images, I'm at first satisfied -- then concerned. (Then ... kind of sleepy ... no, wait. Leave it at concerned.) Something looks wrong with the final front HAZCAM, and after a minute I realize what's bothering me. It's too level.
We wanted to end this drive with a better insolation (solar tilt). Stopped on the slope, with the solar panels aimed at the sun, would be good. Level is bad. It's hard to tell, but the picture looks level.
Oh, shit.
This means we're going to have to scrap the planned IDD work for the sol and hope we can work out a backward drive upslope -- and hope like hell that that drive works.
But before I panic, I check the image headers and do a little math. Our roll is -11.6 degrees, pitch -7.0 degrees, making our overall tilt about 13.5 degrees. RSVP's predictions varied depending on which terrain mesh you used, but it tended to show more like 20 degrees. So this looks bad.
What the hell happened? I ignore the remainder of the meeting, load yestersol's sequence into RSVP and simulate it. Like yestersol, I look at 10% slip (15cm) and 20% slip (30cm). Then I do something I should have done yestersol: I consider worse slips. At 33% slip (45cm) the predicted HAZCAM in RSVP comes out looking almost identical to the actual we just received.
So now we know what went wrong. It was exactly what I was worrying about during the CAM: we slipped more than expected, to the point where we started to level out.
I think hard for a minute about how I want to handle this. As the SOWG meeting breaks up, I activate my mike and tell Ray we might have a problem.
"We don't know that we have one," I tell him, "we'll have to do some more analysis first. But I wanted to let you know we might have to replan the sol to drive instead."
To my surprise, Ray sounds unconcerned. "Okay," he says calmly, "you guys figure it out and we'll do what we need to do."
First I go talk to Rich Petras, the Mobility/IDD guy on duty today. He agrees with me about the slip results (foo!) but doesn't know how to compute the insolation factor from tilt. Neither does our ACS guy, though he's able to show me what the rover will look like as seen from the sun. It looks good, good enough to start me thinking that we might be able to stay put after all. Then again, I don't have a sense of how good it needed to look. On a scale of 0.0 to 1.0, we needed to be about 0.88. Yestersol, we were at about 0.91; if we worsened at all, the rover will survive but we'll feel like dumbasses (that is, I'll feel like a dumbass). We were hoping for something like 0.94 or 0.95. And I can't visually distinguish an attitude that would lead to 0.88 insolation from one that would lead to 0.95 insolation. We need math.
Chris is thisol's floater, and he's in the sequencing MSA when I
return.
"I think we might not need to drive, so I want to get started on the IDD stuff," I tell him. "Can you figure out what our insolation is?"
"Already working on it," he says. He's slinging Perl to get us an approximation.
So he works on that, and I work on the IDD stuff. The script, when he finishes it, reports about a 0.89 or 0.90 insolation, which would be a dropoff from yestersol but good enough that we don't have to move. But only a minute or so after he finishes, Leo Bister comes in with the official word: we're over 0.93. Not only are we good enough, we improved. Not as much of an improvement as we'd hoped, but an improvement all the same.
There's also good news about my IDD sequencing. It's all going smoothly, almost suspiciously smoothly. The scientists have picked a their soil target -- Uxmal, a nice spot right in front of us. When I plug Uxmal into the sequence and run a simulation in RSVP, it works the first time. This is uncommon enough that I go back and check it, but, yes, it really is going to work.
I'm more or less done with the sequence and starting to do the detail work, when Bethany comes in with a request. They've just taken a close look at the PANCAM and there's a perfect patch of soil just by the right front wheel, which is a region that's generally awkward to IDD in. (As it happens, this spot would have been smack in front of us -- in ideal IDD territory -- if we hadn't slipped.)
"Can you get to it?" she asks.
Well, what the hell, I'm game. Everything else seems to be going my way today. She reads off the new target's coordinates and surface normal; I tell RSVP about it, tell the sequence to go there instead of to Uxmal, and simulate it. I'm all prepared for RSVP to spew errors that will take me hours of work to clean up, but nothing doing: like Uxmal, the new target works perfectly the first time.
I'm on a roll, baby.
I have a lot of little details left to attend to, and I even find time for polishing the sequences some. I love it when I find a way to shave a few seconds out of the sequence, to make it just that little bit more elegant -- not only for its own sake, but also because every second we save, every Watt-minute we can squeeze out of the engineering side, we can spend on science. And that's what we're here for, after all.
One of the reasons I have all this time is that, well, let's face it, I'm awesome. But another reason is that there are problems elsewhere in the plan that, like yestersol, slow us down significantly. Once again, we run hours late. Kevin says, "I thought yestersol was the suckiest sol ever. I was wrong. This sol is the suckiest sol ever."
I'm okay with it. My stuff's long since done and I'm ready for conjunction, but more importantly -- much more importantly -- I got a chance to do something I'd been hoping for since the beginning of the mission.
Most of the targets and features we encounter are named by the science team. Every once in a while, the rover drivers get to name something -- I've gotten to do it once or twice -- but it's not common. It's very cool to name something on another planet. The names aren't official, but they do tend to stick; and as when we RAT something, there's a sense of permanence to it.
Since the beginning of the mission, I've been hoping to name something in honor of Jake, since he died only a couple of months before we landed. It didn't seem like the right time when I had the other chances. This one felt right. I don't know why; maybe it's because I've been thinking about him lately, since we moved. Maybe it's some other reason.
Anyway, it fell to me to name the target we abandoned Uxmal for. The tiny little patch of soil our rover will be protecting from the wind throughout the long night of conjunction has a name: "GreenEyes." I miss you, buddy.[1]
Courtesy NASA/JPL-Caltech. The front HAZCAM, showing terrain that's more level than we'd hoped. Aw, crud.
Footnotes:
[1] I still do.
2009-09-04
Spirit Sol 239
The project's in a bit of a tizzy. The email server that handles all of the MER ops mailing lists was cracked a couple of days back, and as the system administrators scramble to get it back online, email service has become woefully unreliable. We rely on email to communicate meeting schedules, and the science teams use it to coordinate their planning, and nothing's getting through to anyone reliably.
So it's a bit of a minor miracle that the SOWG takes place at all, but take place it does. We still haven't gotten the downlink, so we have no idea whether yestersol's crucial drive went as planned. Consequently, we're planning in the blind -- and what a plan they come up with. Yestersol I left with the impression that -- assuming the drive worked -- we'd maybe do a bump drive if need be, and then sit still for conjunction. Somehow that plan flew out the window (or maybe I just didn't get the email), and they've decided to stuff in a bunch of complex IDD work before the drive.
I decide to take this as a challenge, and (despite my irrational but unshakable misgivings about the drive's chances) start sequencing the IDD work as fast as I can, while the SOWG meeting is still going on. I get help from an unexpected source: balky communication equipment. The science teams are mostly remote now, so the project invested in some fiendishly sophisticated hardware and software to enable us to interact. When it's all working, the remote teams are audible through the conference phones and visible on the big projection screens.
When it's all working. Which it mostly isn't. The system fails every few minutes, causing Brenda Franklin, the unlucky scientist stuck with running this stuff, to scramble madly around the room, apologizing to people, whacking buttons, and whispering urgently on her cell phone.
She's not happy. Neither is Ray Arvidson, who's annoyed even when the system is working at its best, because of the audio delays. There's a second or two of lag in the audio, just enough to make conversation difficult. One end of the conversation will sound like this: "I think -- I think we should -- sorry, go ahead -- okay, I think we should -- sorry, go ahead ...." The other interlocutor is saying much the same thing, but offset by a second or so, so they spend more time negotiating who should talk next than they do talking. (I think up a simple protocol: when there's a collision, the person who should proceed is the one whose name is alphabetically first. Arvidson would like this, but I doubt we can sell it to Squyres.) It's like when the anchorman talks to a reporter via satellite phone -- or, more apropos, like when Mission Control talks to an astronaut near the moon. And Houston, we have a problem.
Well, the good news is that I get all of the IDD sequences built even before the first bit of the downlink arrives -- all I need is for the scientists to pick a target, and I can plug that into the sequence and I'm done.
When the downlink starts flowing, I promptly pull up the final front HAZCAM and check out the coordinates in the image header. They're (0, 0, 0) -- we didn't move. Oh, fantastic. We are so boned. I knew I'd fuck something up.
Oh, wait. It's (0, 0, 0) in the new site. And, duh, the terrain is different. Holy shit, we did move.
By the time I've figured this out, the penultimate HAZCAM is down. This one will actually be more useful to me, since it contains the rover's estimate of its position near the end of the drive. That'll give me an idea of whether we got anywhere close to the destination. It's a trivial bit of math to plug in the numbers and -- we're about 1.25m from the destination. Which is excellent -- yestersol, we estimated we'd take this HAZCAM from about 1m or 2m away from the target, depending on slip, so we're right in line with expectations. Unless the rover wigged out in the last couple of drive steps, we should have made it.
When Jeng works it out more precisely, it turns out that we hit the bullseye. Yestersol's goal was to put the rover within 70cm of Tikal -- that is, we had a bullseye with a 70cm radius. Our actual distance to Tikal after this drive: 68cm. Jeng says it's the best drive he's seen in the last month, which might be unfair to the other rover drivers but makes me feel great anyhow.
Not much more data has come down, and a couple of minutes later we learn why. We screwed up the data volume predicts yestersol. It turns out our final attitude is very poor for getting data back for this comm pass (we estimated we'd get 55 Mbits, but we got only about 15), so we're going to have to plan everything using the HAZCAMs and not much else. In particular, the post-drive NAVCAMs aren't coming down. But we probably don't need them. We have acceptable NAVCAM coverage of this area from the previous sol -- we didn't drive that far, after all -- and the penultimate HAZCAM shows us the near field in good detail. We were planning to drive only a meter or so thisol anyhow, and I think we can do it with what we have.
To make matters worse -- or better, depending on your point of view -- part of the right-eye image of the final front HAZCAM was lost in transit due to the poor quality of the comm pass. This leaves us without stereo data for the region immediately in front of the rover, which means we can't plan IDD work for the sol -- without knowing exactly where the ground is, we can't safely move the arm. Consequently, all the work I did building the IDD sequences was a total waste -- but the upside of that is, I can focus all of my energy and attention on the drive, which remains in the plan.
The goal of this drive is twofold. The first goal is simple: if possible, further improve our energy position -- the more we can tilt the solar panels to face the sun, the better. The second goal results from some disputed observations from early in the mission. Some of the scientists think that when we were inadvertently stuck at Adirondack, some interesting things happened to the soil under the rover. (I'm not clear on what these interesting things were, but I think they had to do with the effect on the soil of the way the rover disturbs the wind.)
So the scientists want to use conjunction to do a soil experiment: before conjunction, we image a patch of dirt and drive onto it, disturbing it as little as possible with the wheels. (The interesting stuff will be the soil under the rover body; we just have to be careful not to turn in place or do anything else with the wheels that would disturb that part.) After conjunction, we back out the way we came in, and see what happened.
The resulting drive is, shall we say, elegantly simple. We'll turn 30 degrees to the left -- causing us to face down a short north-facing slope, so that damn near anywhere we stop on the slope will be a good solar attitude -- take some pictures, and drive a meter and a half. (It ends up being slightly more complex than that, as we need to pause halfway through to acquire some MTES images as well.) We get to associate a short name with every sequence; since this is the bump-drive that will take us to Conjunction Junction, I name this one "Conjunction Bumpin'." Then I sit and wait ... and wait ... and wait ....
Because meanwhile, life has been sucking for the rest of the uplink team. We have some unexpected heating requirements, which end up blowing the sol's energy budget and forcing Kevin and the TAP/SIE to replan the sol. (Happily, the drive is untouched, so I can ignore all this except for the delays it introduces.) In the end, they settle for just blowing the damned energy budget; they'll end the day with a net loss in the batteries, but they'll still be above critical levels. They'll make up for it nextersol. This all leads Kevin to declare thisol "The Suckiest Sol Ever."
Kevin's the type to muse aloud about his setbacks. "I think I was too nice today," he says. "I should have said at the SOWG, 'This plan is ridiculous, go change it' .... Tomorrow, I'm gonna be a dick!"
It's so important to have a plan of action.
So the CAM starts three hours late. This exposes yet another problem with remote science teams -- they're all in later time zones than ours. Ray's on Central Time, for instance, so our 22:30 CAM starts at 00:30 for him. He sounds snippy and pissed, not that I blame him.[1]
It's not the kind of sol where you want to find a problem at the CAM. Mindful of this, I keep my voice down when I point out a problem to John (who's floating again thisol). The slope we're heading down is a short one; if we slip too much, we'll reach the bottom and level out, leaving the solar panels aimed straight up, not at the (northerly) sun. This will make things worse for us -- much worse.
I roll my chair over to him. "You think we're going to have a problem if we slip too far?" I ask him quietly.
"I wouldn't worry about it," says John.
"OK, that's what I wanted to hear," I say, and I roll my chair away. I think about it. No, that won't do. I roll my chair back. "OK, why wouldn't you worry about it?"
"If we start to level out," he points out, "we'll stop slipping."
Duh. I roll my chair away again.
And I think about that answer. No, that won't do, either; by the time we've leveled out enough to stop slipping, our solar attitude will already be terrible. I need to know this, or I'm not going to be able to sleep, so I model 10% and 20% slips in RSVP. The results have to be taken with a grain of salt since our terrain data is so limited thisol, but ... 10% slip is fine; 20% slip isn't as good as the no-slip case, but it still leaves us with a good solar attitude.
And that's what I wanted to hear.
Footnotes:
[1] As I've learned since then, Ray is a classic morning person. He hates late hours, and like most morning people, he really hates Mars time. That didn't stop him from living on Mars time as the science team lead for Phoenix a few years after this, though.
So it's a bit of a minor miracle that the SOWG takes place at all, but take place it does. We still haven't gotten the downlink, so we have no idea whether yestersol's crucial drive went as planned. Consequently, we're planning in the blind -- and what a plan they come up with. Yestersol I left with the impression that -- assuming the drive worked -- we'd maybe do a bump drive if need be, and then sit still for conjunction. Somehow that plan flew out the window (or maybe I just didn't get the email), and they've decided to stuff in a bunch of complex IDD work before the drive.
I decide to take this as a challenge, and (despite my irrational but unshakable misgivings about the drive's chances) start sequencing the IDD work as fast as I can, while the SOWG meeting is still going on. I get help from an unexpected source: balky communication equipment. The science teams are mostly remote now, so the project invested in some fiendishly sophisticated hardware and software to enable us to interact. When it's all working, the remote teams are audible through the conference phones and visible on the big projection screens.
When it's all working. Which it mostly isn't. The system fails every few minutes, causing Brenda Franklin, the unlucky scientist stuck with running this stuff, to scramble madly around the room, apologizing to people, whacking buttons, and whispering urgently on her cell phone.
She's not happy. Neither is Ray Arvidson, who's annoyed even when the system is working at its best, because of the audio delays. There's a second or two of lag in the audio, just enough to make conversation difficult. One end of the conversation will sound like this: "I think -- I think we should -- sorry, go ahead -- okay, I think we should -- sorry, go ahead ...." The other interlocutor is saying much the same thing, but offset by a second or so, so they spend more time negotiating who should talk next than they do talking. (I think up a simple protocol: when there's a collision, the person who should proceed is the one whose name is alphabetically first. Arvidson would like this, but I doubt we can sell it to Squyres.) It's like when the anchorman talks to a reporter via satellite phone -- or, more apropos, like when Mission Control talks to an astronaut near the moon. And Houston, we have a problem.
Well, the good news is that I get all of the IDD sequences built even before the first bit of the downlink arrives -- all I need is for the scientists to pick a target, and I can plug that into the sequence and I'm done.
When the downlink starts flowing, I promptly pull up the final front HAZCAM and check out the coordinates in the image header. They're (0, 0, 0) -- we didn't move. Oh, fantastic. We are so boned. I knew I'd fuck something up.
Oh, wait. It's (0, 0, 0) in the new site. And, duh, the terrain is different. Holy shit, we did move.
By the time I've figured this out, the penultimate HAZCAM is down. This one will actually be more useful to me, since it contains the rover's estimate of its position near the end of the drive. That'll give me an idea of whether we got anywhere close to the destination. It's a trivial bit of math to plug in the numbers and -- we're about 1.25m from the destination. Which is excellent -- yestersol, we estimated we'd take this HAZCAM from about 1m or 2m away from the target, depending on slip, so we're right in line with expectations. Unless the rover wigged out in the last couple of drive steps, we should have made it.
When Jeng works it out more precisely, it turns out that we hit the bullseye. Yestersol's goal was to put the rover within 70cm of Tikal -- that is, we had a bullseye with a 70cm radius. Our actual distance to Tikal after this drive: 68cm. Jeng says it's the best drive he's seen in the last month, which might be unfair to the other rover drivers but makes me feel great anyhow.
Not much more data has come down, and a couple of minutes later we learn why. We screwed up the data volume predicts yestersol. It turns out our final attitude is very poor for getting data back for this comm pass (we estimated we'd get 55 Mbits, but we got only about 15), so we're going to have to plan everything using the HAZCAMs and not much else. In particular, the post-drive NAVCAMs aren't coming down. But we probably don't need them. We have acceptable NAVCAM coverage of this area from the previous sol -- we didn't drive that far, after all -- and the penultimate HAZCAM shows us the near field in good detail. We were planning to drive only a meter or so thisol anyhow, and I think we can do it with what we have.
To make matters worse -- or better, depending on your point of view -- part of the right-eye image of the final front HAZCAM was lost in transit due to the poor quality of the comm pass. This leaves us without stereo data for the region immediately in front of the rover, which means we can't plan IDD work for the sol -- without knowing exactly where the ground is, we can't safely move the arm. Consequently, all the work I did building the IDD sequences was a total waste -- but the upside of that is, I can focus all of my energy and attention on the drive, which remains in the plan.
The goal of this drive is twofold. The first goal is simple: if possible, further improve our energy position -- the more we can tilt the solar panels to face the sun, the better. The second goal results from some disputed observations from early in the mission. Some of the scientists think that when we were inadvertently stuck at Adirondack, some interesting things happened to the soil under the rover. (I'm not clear on what these interesting things were, but I think they had to do with the effect on the soil of the way the rover disturbs the wind.)
So the scientists want to use conjunction to do a soil experiment: before conjunction, we image a patch of dirt and drive onto it, disturbing it as little as possible with the wheels. (The interesting stuff will be the soil under the rover body; we just have to be careful not to turn in place or do anything else with the wheels that would disturb that part.) After conjunction, we back out the way we came in, and see what happened.
The resulting drive is, shall we say, elegantly simple. We'll turn 30 degrees to the left -- causing us to face down a short north-facing slope, so that damn near anywhere we stop on the slope will be a good solar attitude -- take some pictures, and drive a meter and a half. (It ends up being slightly more complex than that, as we need to pause halfway through to acquire some MTES images as well.) We get to associate a short name with every sequence; since this is the bump-drive that will take us to Conjunction Junction, I name this one "Conjunction Bumpin'." Then I sit and wait ... and wait ... and wait ....
Because meanwhile, life has been sucking for the rest of the uplink team. We have some unexpected heating requirements, which end up blowing the sol's energy budget and forcing Kevin and the TAP/SIE to replan the sol. (Happily, the drive is untouched, so I can ignore all this except for the delays it introduces.) In the end, they settle for just blowing the damned energy budget; they'll end the day with a net loss in the batteries, but they'll still be above critical levels. They'll make up for it nextersol. This all leads Kevin to declare thisol "The Suckiest Sol Ever."
Kevin's the type to muse aloud about his setbacks. "I think I was too nice today," he says. "I should have said at the SOWG, 'This plan is ridiculous, go change it' .... Tomorrow, I'm gonna be a dick!"
It's so important to have a plan of action.
So the CAM starts three hours late. This exposes yet another problem with remote science teams -- they're all in later time zones than ours. Ray's on Central Time, for instance, so our 22:30 CAM starts at 00:30 for him. He sounds snippy and pissed, not that I blame him.[1]
It's not the kind of sol where you want to find a problem at the CAM. Mindful of this, I keep my voice down when I point out a problem to John (who's floating again thisol). The slope we're heading down is a short one; if we slip too much, we'll reach the bottom and level out, leaving the solar panels aimed straight up, not at the (northerly) sun. This will make things worse for us -- much worse.
I roll my chair over to him. "You think we're going to have a problem if we slip too far?" I ask him quietly.
"I wouldn't worry about it," says John.
"OK, that's what I wanted to hear," I say, and I roll my chair away. I think about it. No, that won't do. I roll my chair back. "OK, why wouldn't you worry about it?"
"If we start to level out," he points out, "we'll stop slipping."
Duh. I roll my chair away again.
And I think about that answer. No, that won't do, either; by the time we've leveled out enough to stop slipping, our solar attitude will already be terrible. I need to know this, or I'm not going to be able to sleep, so I model 10% and 20% slips in RSVP. The results have to be taken with a grain of salt since our terrain data is so limited thisol, but ... 10% slip is fine; 20% slip isn't as good as the no-slip case, but it still leaves us with a good solar attitude.
And that's what I wanted to hear.
Footnotes:
[1] As I've learned since then, Ray is a classic morning person. He hates late hours, and like most morning people, he really hates Mars time. That didn't stop him from living on Mars time as the science team lead for Phoenix a few years after this, though.
2009-09-03
Spirit Sol 238
I'm running late and there's no parking, but I still manage to make it up to the SOWG room right on time. Where I find an ongoing meeting. Turns out they revised the schedule, bumping up the meeting half an hour. So I'm not barely on time, I'm horribly late. That's always a great way to start your day.
It also turns out they've changed the plan, again without telling me. (Though to be fair, maybe I'd have known this earlier if I'd known when the SOWG meeting was and I'd been able to get there on time.) We're going to make up for our lost sol by compressing the two drive sols into one: we'll drive to Anasazi_station, image Anasazi, and drive to Tikal, all in the same sol. But I don't learn this until after the SOWG meeting, so the duration estimates we use for the plan are way too short, which means we have to replan later.
I complain about all this to John (thisol's floating RP), and he just grins and says, "This is so cool ...." Once again, this simple phrase snaps me back into a good mood. Bastard!
So we need another thirty minutes for the extra driving (it's only about three meters and some turning, but visodom slows things down a lot), and this simply breaks the plan -- there's not enough energy to do it all. The science team decides to nix the dogleg to Anasazi_station, as well as the associated PANCAM imaging. (Thus disappointing Heather, who's already built the PANCAM sequences. But as always, she's a good sport about it.) This leaves us with a straight drive to Tikal and plenty of time to do it.
The more complex drive was already built, but I decide to follow Heather's example and be a good sport about it. Wincing internally, I rip out about three-quarters of the drive sequence and redo it as a straight drive to Tikal. The rest of the work is mainly analysis, to see whether we're going to be at a good solar tilt if we error out, and stuff like that. Turns out there's nothing to worry about: the insolation maps -- colored terrain overlays showing the goodness of our sun-relative tilt at each point in an image -- show the path from us to Tikal as being completely safe. In these maps, blue is good, green is so-so, red is bad. And the path from here to Tikal is a big blue highway.
Though still under the weather, Mark Adler is back as thisol's Mission Manager. Every Mission Manager has his own style. Mark's is to ask a few really tough questions to see if you seem to have your shit together. If you pass the test, his comfort level increases and he leaves you alone.
Thisol he decides to make the test open-book: he writes the questions down on the MERboard, and announces that this is what he's going to be asking at the CAM. Nearly all of them are for me, to wit: (1) What tilt limit was chosen for this drive? (2) How was that limit derived? (3) If the drive faults out due to a tilt error (or any other error), how will we recover in time for conjunction? (4) What is our insolation along the drive path?
Having the list in advance makes my life about a zillion times easier. I make time before the CAM to discuss my answers with Mark. (Which is the way to do it -- early, I mean.) As I'm talking to him, I watch the comfort level rise above his critical threshold. He visibly relaxes, and the drive is on.
I'm glad I've already gotten this out of the way when, ten minutes or so before the CAM, John and I notice a rock-ringed depression just in front of the rover and along our drive path. (Indeed, the encircled depression looks uncannily like a fire pit.) To a first approximation, it's not a drive obstacle. It's only about 20cm deep, from the top of the tallest rock to the lowest spot we can find. But there are some aspects of its shape that worry us. For one thing, the path from the bottom of the depression to the top of that tallest rock is nearly vertical -- a mini-cliff, which the rover would have a hard time scaling. Moreover, the area immediately in front of the mini-cliff is just about one wheel diameter across. This reminds me of a "feature" of the rover, a problem that arises because it can't lift its own weight. You can build a kind of rover trap, a hole just big enough for one wheel, which the rover will have a hard time extricating itself from. Put all six wheels in such a trap, and the rover turns into a lander.
We soon deduce that if the rover gets stuck in the fire pit, we'll be able to get it back out -- eventually. Probably, we could just have it turn in place and it would climb out the side. The problem is that we don't have any sols we can afford to spend doing this; if we get stuck in the fire pit, we may have to remain stuck until after conjunction. That's assuming that the attitude change induced by dropping a wheel into the pit doesn't blow our insolation, causing the rover to drain its batteries during conjunction and freeze to death. In which case, we'll still be there after conjunction ... and for a long time afterward. (OK, so that's a worst-case scenario. But worrying about worst-case scenarios is what they pay me for.)
Ultimately, we conclude there's no reasonable risk. The depression is quite near us, only about a meter away, so we won't accumulate much uncertainty before we reach it. The likely case is that we'll just drive straight over it, mostly straddling the depression, and in particular straddling the worst-case area.
Ah, it's always something.
Courtesy NASA/JPL-Caltech. The rock-ringed depression we started to worry about is straight up the middle of this image.
It also turns out they've changed the plan, again without telling me. (Though to be fair, maybe I'd have known this earlier if I'd known when the SOWG meeting was and I'd been able to get there on time.) We're going to make up for our lost sol by compressing the two drive sols into one: we'll drive to Anasazi_station, image Anasazi, and drive to Tikal, all in the same sol. But I don't learn this until after the SOWG meeting, so the duration estimates we use for the plan are way too short, which means we have to replan later.
I complain about all this to John (thisol's floating RP), and he just grins and says, "This is so cool ...." Once again, this simple phrase snaps me back into a good mood. Bastard!
So we need another thirty minutes for the extra driving (it's only about three meters and some turning, but visodom slows things down a lot), and this simply breaks the plan -- there's not enough energy to do it all. The science team decides to nix the dogleg to Anasazi_station, as well as the associated PANCAM imaging. (Thus disappointing Heather, who's already built the PANCAM sequences. But as always, she's a good sport about it.) This leaves us with a straight drive to Tikal and plenty of time to do it.
The more complex drive was already built, but I decide to follow Heather's example and be a good sport about it. Wincing internally, I rip out about three-quarters of the drive sequence and redo it as a straight drive to Tikal. The rest of the work is mainly analysis, to see whether we're going to be at a good solar tilt if we error out, and stuff like that. Turns out there's nothing to worry about: the insolation maps -- colored terrain overlays showing the goodness of our sun-relative tilt at each point in an image -- show the path from us to Tikal as being completely safe. In these maps, blue is good, green is so-so, red is bad. And the path from here to Tikal is a big blue highway.
Though still under the weather, Mark Adler is back as thisol's Mission Manager. Every Mission Manager has his own style. Mark's is to ask a few really tough questions to see if you seem to have your shit together. If you pass the test, his comfort level increases and he leaves you alone.
Thisol he decides to make the test open-book: he writes the questions down on the MERboard, and announces that this is what he's going to be asking at the CAM. Nearly all of them are for me, to wit: (1) What tilt limit was chosen for this drive? (2) How was that limit derived? (3) If the drive faults out due to a tilt error (or any other error), how will we recover in time for conjunction? (4) What is our insolation along the drive path?
Having the list in advance makes my life about a zillion times easier. I make time before the CAM to discuss my answers with Mark. (Which is the way to do it -- early, I mean.) As I'm talking to him, I watch the comfort level rise above his critical threshold. He visibly relaxes, and the drive is on.
I'm glad I've already gotten this out of the way when, ten minutes or so before the CAM, John and I notice a rock-ringed depression just in front of the rover and along our drive path. (Indeed, the encircled depression looks uncannily like a fire pit.) To a first approximation, it's not a drive obstacle. It's only about 20cm deep, from the top of the tallest rock to the lowest spot we can find. But there are some aspects of its shape that worry us. For one thing, the path from the bottom of the depression to the top of that tallest rock is nearly vertical -- a mini-cliff, which the rover would have a hard time scaling. Moreover, the area immediately in front of the mini-cliff is just about one wheel diameter across. This reminds me of a "feature" of the rover, a problem that arises because it can't lift its own weight. You can build a kind of rover trap, a hole just big enough for one wheel, which the rover will have a hard time extricating itself from. Put all six wheels in such a trap, and the rover turns into a lander.
We soon deduce that if the rover gets stuck in the fire pit, we'll be able to get it back out -- eventually. Probably, we could just have it turn in place and it would climb out the side. The problem is that we don't have any sols we can afford to spend doing this; if we get stuck in the fire pit, we may have to remain stuck until after conjunction. That's assuming that the attitude change induced by dropping a wheel into the pit doesn't blow our insolation, causing the rover to drain its batteries during conjunction and freeze to death. In which case, we'll still be there after conjunction ... and for a long time afterward. (OK, so that's a worst-case scenario. But worrying about worst-case scenarios is what they pay me for.)
Ultimately, we conclude there's no reasonable risk. The depression is quite near us, only about a meter away, so we won't accumulate much uncertainty before we reach it. The likely case is that we'll just drive straight over it, mostly straddling the depression, and in particular straddling the worst-case area.
Ah, it's always something.
Courtesy NASA/JPL-Caltech. The rock-ringed depression we started to worry about is straight up the middle of this image.
2009-09-02
Spirit Sol 237
I have an interview this morning, with a reporter from the London Sunday Times. He's here to do a car-review-style piece on the rovers. The sample piece he emailed me makes it clear this is to be a light-hearted article, and I'm looking forward to it.
Only one problem: the press office sent me a time for the interview, but not a place. We eventually get that sorted out; it turns out the reporter's running late anyway, giving me time to attend a meeting to decide whether we should drive before the upcoming solar conjunction period.
My feeling is, no: we're receiving a good amount of solar energy right where we are, so why risk moving? Better to be conservative; sit still for the few remaining pre-conjunction sols. A bird in the hand, etc.
But I don't bother voicing this view, as I don't feel strongly about it and it rapidly becomes clear that everyone else thinks we should drive. The scientists are keen to visit Tikal, a spot about 9m away. Nine meters used to be a doddle -- not so long ago, we commonly drove ten times that far in a typical sol. But driving on slopes is trickier; we've been having a lot of trouble with our drives since we started climbing West Spur. What's more, we might have a narrow target to hit, and precision driving with these vehicles is always hard, even on level ground.
The tentative plan that emerges is to spend sol 237 finishing up our IDD work at Ebenezer and driving eight or nine meters to a spot called Anasazi_station, where we'll take nice PANCAMs of an interesting-looking rock called, you guessed it, Anasazi. On sol 238, we drive from Anasazi_station to Tikal, only about another three meters. On sol 239, we do fine positioning if needed to tweak our attitude so we can get more solar energy. That leaves us a contingency sol before the hard limit after sol 240 -- due to the upcoming solar conjunction, we will not drive after sol 240 no matter what.
That plan's fine by everyone in the room. But Jim Erickson is not in the room, and as Art points out, Jim already nixed the drive to Anasazi_station -- Jim wants to keep things simple, and to get us to our solar conjunction destination sooner rather than later. (Which is pretty much what I was thinking. Evidently, I'm project manager material.) This surprises Squyres, and he and Mark Adler decide they'll try to change Jim's mind: apparently they've refined their estimate of the start of conjunction, and Jim might have been thinking we had a sol less than we do.
Oh, and incidentally, everyone has already picked out a name for the spot where we spend solar conjunction. Wherever that may turn out to be, we're calling it "Conjunction Junction."
You'll never guess what they're planning to use as the wakeup song.
That's the end of the meeting and the start of my interview. The reporter, John Arlidge, is a tall skinny fellow accompanied by a photographer (Paul Harris). "John and Paul," I say, shaking hands. I could resist if they weren't British, but as it is ... "Where are George and Ringo?" I ask. They have the good grace to laugh at this, and we're off to the ISIL so they can get pictures of me pretending to drive the testbed rover.
John decides to start the interview while we're waiting for Paul to set up his equipment. "Noisy in here," he says. "Let's try a sound check." He puts the tape recorder on a table next to me. "Say anything," he says. "Tell me what you had for breakfast."
"I didn't have breakfast," I tell him. "I was so excited to come here and talk to you, I skipped it entirely."
He laughs and gives me the finger. "Fuck you," he says cheerfully.
So this is a reporter I can deal with.
I give John a little background about the rovers -- their basic capabilities, environmental conditions, what we've been up to, where we're going, stuff like that -- until Paul's ready. Then I don one of the anti-static coats -- we really wear these things when working in the testbed, but I feel like a dope because I realize it's going to make me look like a pharmacist in a commercial for headache pills -- and walk across the Mars-like sand to the testbed rover. I grin idiotically at Paul while he snaps some pictures of me standing there, sitting there pretending to drive the rover with a laptop, and so on. His camera's digital, so he shows me some of the pictures afterward, and I tell him, "I think the ones where I don't look like a homicidal maniac are the best ones." He agrees.
So then we all walk back to the sequencing room in Building 264. John, being smarter than Paul and me put together, falls behind us as he keeps pace with Charli, the attractive young woman from JPL's media office. (It's her second time this morning walking uphill across the Lab -- in high heels -- and she's slowing down.) Paul, it turns out, lives here now, in Woodland Hills, but he gets back to London a couple of times a year to visit his parents. I ask him about London and he asks me about the rovers, and I get the definite impression he's more interested in the vehicles than John is. John is more interested in Charli. As I said, he's clearly the smart one.
We spend another 45 minutes or an hour talking in the sequencing room, though it seems less of an interview and more of a brainstorming session -- brainstorming about what funny and clever things John could write in his article. Whether there's valet service on Mars, what kinds of girls you could pick up with a Mars rover ("smart, science-oriented, and very patient ones," is my answer), that kind of thing. Meanwhile Paul takes pictures; I've set up a drive animation to loop on the projection screen behind me, and I try not to look into the camera as he flits and shoots. Paul eventually puts his camera away, but has to haul it back out when John points out the "How's My Driving?" sign taped to the back of my chair.
Then it's over. Or nearly. "My last interview before you was with Damon Dash, the producer behind Jay-Z," John says. "He got a free Ford Explorer just for driving it around and saying whether it was bling. I bet you could do something like that."
"I don't think our ethics people would like that," I reply tactfully. Not that I haven't thought about it. But really: the job is worth more to me than some lousy car. I already get to drive the coolest vehicle in the solar system, what the hell do I need with a monstrous, gas-guzzling Ford Explorer?
Meanwhile, back on Earth, the news is not so good. Yestersol was supposed to be a touch-and-go, but when we get the data, it turns out we didn't go anywhere. Apparently, Chris badly underestimated the IDD sequence duration, so when the rover tried to drive, it noticed that the mobility time-of-day limit had passed and refused to move. This jeopardizes the long-term schedule we worked out earlier in the day, because it means we'll have to spend thisol redoing part of yestersol -- effectively, we blew our contingency sol before we even started.
"So Chris is fired," says Adler. "But he's rehired, because we need him for today."
It's uncommon for us to redo the previous sol like this, but it does make the sequencing easy -- we can usually just pick up yestersol's sequence, make a few minor changes (or not), and we're all done. Which is how it works out today. I have very little real work to do, I mainly struggle heroically to catch up with the email backlog that accumulated while I was out of town. (The backlog is exacerbated by worms that automatically spew email across the Lab. I read my email under a niche mailer on a Linux box, so I'm immune to the worms themselves, but I still have to put up with the junk messages they send out in their efforts to propagate. My productivity would double if the Lab would ban Windows, and I don't even use the fucking thing.)
Adler's under the weather, so he goes home and Jim Erickson fills in as Mission Manager for the sol. Jim hasn't worked on Spirit in a long time, and he's alarmed by some things we take for granted, like driving on sharp tilts. We're expecting a max tilt a little over 20 degrees thisol, so I set the limit (beyond which the rover will automatically stop moving) at 30 degrees. "We'd be freaking out on Opportunity right now," Jim says, looking at me suspiciously.
Ray (participating remotely, via conference call) reassures Jim that we do this all the time. Jim still looks worried even after Ray's reassurance, but then, Jim always looks like that. As the CAM progresses, Jim turns to me and asks, sotto voce, if I've worked on Opportunity yet. I tell him about my one chance to do so, which was lost because they were in a restricted sol and didn't need me. "You should work on Opportunity," he says. He vows to talk to Arthur about it when Arthur returns from travel. Fine by me!
I should have paid more attention to the drive sequence and less to my email. Jake Matijevic catches something I should have caught: since yestersol's drive failed, the rover set its goal-error flag, and we neglected to clear the flag in thisol's drive sequence. Thankfully, it's a trivial change, but I'm ashamed of missing it. (Normally I check the downlink report to see if any flags need to be cleared, but because of the late downlink the report hadn't been written yet when I checked, and I forgot to recheck it later. But I should have thought of it anyway, downlink report or no downlink report. Sheesh, how long have I been doing this?) And I don't feel any better when Ray says, "Good thing you were there, Jake," in a tone that makes it clear that, shall we say, he agrees I should have caught it.
He's right, though, that it is a good thing Jake was there: we already blew our only contingency sol, and this rookie mistake would have cost us another. If he hadn't been on the alert, we'd have lost a significant pre-conjunction science opportunity.
I reflexively beat myself up over this, but after reflecting on it a while, I start to feel less bad. This is why we have teams, after all: you're going to fuck up once in a while, and other people are there to backstop you. Which makes me realize that I haven't been doing my part as a team member -- I tend to do other things during the parts of the sequence walkthrough and CAM that don't directly affect me. So I decide to pay more attention during these meetings, in the hope that I can pay Jake's favor back, or at least pay it forward.
When the CAM is over, I start looking ahead at the schedule. From now until solar conjunction, I'm the only rover driver scheduled for Spirit. There's a floater scheduled for each of those sols, but it's not the same as having a second RP who's exclusively dedicated to the same rover. And they're going to be unusually important and challenging sols, with precision driving, and likely IDD on each sol, to boot. We don't have any more contingency sols to spend, and if we get something wrong, we could actually lose the vehicle: if I manage to put Spirit in a poor solar attitude before we lose contact during conjunction, she could drain her batteries, fail to heat, and the cold could kill her.
It's all going to be up to me.
It's a good thing Jake is there.
Only one problem: the press office sent me a time for the interview, but not a place. We eventually get that sorted out; it turns out the reporter's running late anyway, giving me time to attend a meeting to decide whether we should drive before the upcoming solar conjunction period.
My feeling is, no: we're receiving a good amount of solar energy right where we are, so why risk moving? Better to be conservative; sit still for the few remaining pre-conjunction sols. A bird in the hand, etc.
But I don't bother voicing this view, as I don't feel strongly about it and it rapidly becomes clear that everyone else thinks we should drive. The scientists are keen to visit Tikal, a spot about 9m away. Nine meters used to be a doddle -- not so long ago, we commonly drove ten times that far in a typical sol. But driving on slopes is trickier; we've been having a lot of trouble with our drives since we started climbing West Spur. What's more, we might have a narrow target to hit, and precision driving with these vehicles is always hard, even on level ground.
The tentative plan that emerges is to spend sol 237 finishing up our IDD work at Ebenezer and driving eight or nine meters to a spot called Anasazi_station, where we'll take nice PANCAMs of an interesting-looking rock called, you guessed it, Anasazi. On sol 238, we drive from Anasazi_station to Tikal, only about another three meters. On sol 239, we do fine positioning if needed to tweak our attitude so we can get more solar energy. That leaves us a contingency sol before the hard limit after sol 240 -- due to the upcoming solar conjunction, we will not drive after sol 240 no matter what.
That plan's fine by everyone in the room. But Jim Erickson is not in the room, and as Art points out, Jim already nixed the drive to Anasazi_station -- Jim wants to keep things simple, and to get us to our solar conjunction destination sooner rather than later. (Which is pretty much what I was thinking. Evidently, I'm project manager material.) This surprises Squyres, and he and Mark Adler decide they'll try to change Jim's mind: apparently they've refined their estimate of the start of conjunction, and Jim might have been thinking we had a sol less than we do.
Oh, and incidentally, everyone has already picked out a name for the spot where we spend solar conjunction. Wherever that may turn out to be, we're calling it "Conjunction Junction."
You'll never guess what they're planning to use as the wakeup song.
That's the end of the meeting and the start of my interview. The reporter, John Arlidge, is a tall skinny fellow accompanied by a photographer (Paul Harris). "John and Paul," I say, shaking hands. I could resist if they weren't British, but as it is ... "Where are George and Ringo?" I ask. They have the good grace to laugh at this, and we're off to the ISIL so they can get pictures of me pretending to drive the testbed rover.
John decides to start the interview while we're waiting for Paul to set up his equipment. "Noisy in here," he says. "Let's try a sound check." He puts the tape recorder on a table next to me. "Say anything," he says. "Tell me what you had for breakfast."
"I didn't have breakfast," I tell him. "I was so excited to come here and talk to you, I skipped it entirely."
He laughs and gives me the finger. "Fuck you," he says cheerfully.
So this is a reporter I can deal with.
I give John a little background about the rovers -- their basic capabilities, environmental conditions, what we've been up to, where we're going, stuff like that -- until Paul's ready. Then I don one of the anti-static coats -- we really wear these things when working in the testbed, but I feel like a dope because I realize it's going to make me look like a pharmacist in a commercial for headache pills -- and walk across the Mars-like sand to the testbed rover. I grin idiotically at Paul while he snaps some pictures of me standing there, sitting there pretending to drive the rover with a laptop, and so on. His camera's digital, so he shows me some of the pictures afterward, and I tell him, "I think the ones where I don't look like a homicidal maniac are the best ones." He agrees.
So then we all walk back to the sequencing room in Building 264. John, being smarter than Paul and me put together, falls behind us as he keeps pace with Charli, the attractive young woman from JPL's media office. (It's her second time this morning walking uphill across the Lab -- in high heels -- and she's slowing down.) Paul, it turns out, lives here now, in Woodland Hills, but he gets back to London a couple of times a year to visit his parents. I ask him about London and he asks me about the rovers, and I get the definite impression he's more interested in the vehicles than John is. John is more interested in Charli. As I said, he's clearly the smart one.
We spend another 45 minutes or an hour talking in the sequencing room, though it seems less of an interview and more of a brainstorming session -- brainstorming about what funny and clever things John could write in his article. Whether there's valet service on Mars, what kinds of girls you could pick up with a Mars rover ("smart, science-oriented, and very patient ones," is my answer), that kind of thing. Meanwhile Paul takes pictures; I've set up a drive animation to loop on the projection screen behind me, and I try not to look into the camera as he flits and shoots. Paul eventually puts his camera away, but has to haul it back out when John points out the "How's My Driving?" sign taped to the back of my chair.
Then it's over. Or nearly. "My last interview before you was with Damon Dash, the producer behind Jay-Z," John says. "He got a free Ford Explorer just for driving it around and saying whether it was bling. I bet you could do something like that."
"I don't think our ethics people would like that," I reply tactfully. Not that I haven't thought about it. But really: the job is worth more to me than some lousy car. I already get to drive the coolest vehicle in the solar system, what the hell do I need with a monstrous, gas-guzzling Ford Explorer?
Meanwhile, back on Earth, the news is not so good. Yestersol was supposed to be a touch-and-go, but when we get the data, it turns out we didn't go anywhere. Apparently, Chris badly underestimated the IDD sequence duration, so when the rover tried to drive, it noticed that the mobility time-of-day limit had passed and refused to move. This jeopardizes the long-term schedule we worked out earlier in the day, because it means we'll have to spend thisol redoing part of yestersol -- effectively, we blew our contingency sol before we even started.
"So Chris is fired," says Adler. "But he's rehired, because we need him for today."
It's uncommon for us to redo the previous sol like this, but it does make the sequencing easy -- we can usually just pick up yestersol's sequence, make a few minor changes (or not), and we're all done. Which is how it works out today. I have very little real work to do, I mainly struggle heroically to catch up with the email backlog that accumulated while I was out of town. (The backlog is exacerbated by worms that automatically spew email across the Lab. I read my email under a niche mailer on a Linux box, so I'm immune to the worms themselves, but I still have to put up with the junk messages they send out in their efforts to propagate. My productivity would double if the Lab would ban Windows, and I don't even use the fucking thing.)
Adler's under the weather, so he goes home and Jim Erickson fills in as Mission Manager for the sol. Jim hasn't worked on Spirit in a long time, and he's alarmed by some things we take for granted, like driving on sharp tilts. We're expecting a max tilt a little over 20 degrees thisol, so I set the limit (beyond which the rover will automatically stop moving) at 30 degrees. "We'd be freaking out on Opportunity right now," Jim says, looking at me suspiciously.
Ray (participating remotely, via conference call) reassures Jim that we do this all the time. Jim still looks worried even after Ray's reassurance, but then, Jim always looks like that. As the CAM progresses, Jim turns to me and asks, sotto voce, if I've worked on Opportunity yet. I tell him about my one chance to do so, which was lost because they were in a restricted sol and didn't need me. "You should work on Opportunity," he says. He vows to talk to Arthur about it when Arthur returns from travel. Fine by me!
I should have paid more attention to the drive sequence and less to my email. Jake Matijevic catches something I should have caught: since yestersol's drive failed, the rover set its goal-error flag, and we neglected to clear the flag in thisol's drive sequence. Thankfully, it's a trivial change, but I'm ashamed of missing it. (Normally I check the downlink report to see if any flags need to be cleared, but because of the late downlink the report hadn't been written yet when I checked, and I forgot to recheck it later. But I should have thought of it anyway, downlink report or no downlink report. Sheesh, how long have I been doing this?) And I don't feel any better when Ray says, "Good thing you were there, Jake," in a tone that makes it clear that, shall we say, he agrees I should have caught it.
He's right, though, that it is a good thing Jake was there: we already blew our only contingency sol, and this rookie mistake would have cost us another. If he hadn't been on the alert, we'd have lost a significant pre-conjunction science opportunity.
I reflexively beat myself up over this, but after reflecting on it a while, I start to feel less bad. This is why we have teams, after all: you're going to fuck up once in a while, and other people are there to backstop you. Which makes me realize that I haven't been doing my part as a team member -- I tend to do other things during the parts of the sequence walkthrough and CAM that don't directly affect me. So I decide to pay more attention during these meetings, in the hope that I can pay Jake's favor back, or at least pay it forward.
When the CAM is over, I start looking ahead at the schedule. From now until solar conjunction, I'm the only rover driver scheduled for Spirit. There's a floater scheduled for each of those sols, but it's not the same as having a second RP who's exclusively dedicated to the same rover. And they're going to be unusually important and challenging sols, with precision driving, and likely IDD on each sol, to boot. We don't have any more contingency sols to spend, and if we get something wrong, we could actually lose the vehicle: if I manage to put Spirit in a poor solar attitude before we lose contact during conjunction, she could drain her batteries, fail to heat, and the cold could kill her.
It's all going to be up to me.
It's a good thing Jake is there.
2009-08-28
Spirit Sol 232
The longer we stay at a rock target, the easier exploring it becomes. In part this is because we can reuse successful commands from previous sols, leveraging our previous problem solving.
It's thanks in part to this effect that Ashitey is already done with the sequence by the time I come in. And it looks like it's going to be a short day. Kevin Talley, our TUL today, wants to get out of here to play with a new flight simulator he's hoping UPS will bring him this afternoon.
Such an easy sol. For the first time in a long time, we actually run ahead of schedule and finish an hour early.
So now we know: want to stay on schedule? Buy Kevin a new flight simulator. If only we'd known that back on sol 1.[1]
[Next post: sol 237, September 2.]
Footnotes:
[1] Kevin left for a while to work on Phoenix, and is now back on MER, training as a rover driver. I'd forgotten this particular insight until now, but will have to keep it in mind for some time when I'm on shift with him and need to hurry the day along.
It's thanks in part to this effect that Ashitey is already done with the sequence by the time I come in. And it looks like it's going to be a short day. Kevin Talley, our TUL today, wants to get out of here to play with a new flight simulator he's hoping UPS will bring him this afternoon.
Such an easy sol. For the first time in a long time, we actually run ahead of schedule and finish an hour early.
So now we know: want to stay on schedule? Buy Kevin a new flight simulator. If only we'd known that back on sol 1.[1]
[Next post: sol 237, September 2.]
Footnotes:
[1] Kevin left for a while to work on Phoenix, and is now back on MER, training as a rover driver. I'd forgotten this particular insight until now, but will have to keep it in mind for some time when I'm on shift with him and need to hurry the day along.
2009-08-27
Spirit Sol 231
This morning is one of those mornings that makes me appreciate all the mornings that aren't like this morning.
But there's good news when I get to work. Yestersol's sequence worked out fine, despite the wacky joint moves we used. Yestersol's focus was on brushing Ebenezer with the RAT; thisol we're following that up by grinding. Leaving an eternal mark on another world -- it's a strange kind of immortality, but I have an inexhaustible appetite for it.
After the grind, we APXS the RAT hole. As a measure of how cold it's getting on Mars, we can APXS at mid-day -- since the APXS works best in the cold, we used to have to wait until late at night to start it. So the warmest part of our day is now about as cold as the coldest part of our day used to be. Poor Spirit. Hang in there, baby, summer's coming. Just a few more months ....
Of course, the colder temperatures, and reduced sun exposure, mean we have less energy to play with. So the RAT's tail gets amputated -- what starts as a three-hour grind (insert Gilligan's Island reference here) is cut to two and a half hours, then to two. Like any of the scientists, the RAT guys' faces fall a little more each time they're cut. I slide over to one of them, Phil Chu, and commiserate. "That's the same thing that used to happen to us all the time on drive sols -- it starts out as a four-hour drive and you end up with fifteen minutes." Phil laughs. "Ah, it's not a problem," he says. And he's probably right, at that -- Ebenezer's a soft rock; even with only two hours to run, the RAT will take a good chunk out of it.
I'll never have kids, but I'll make an indelible hole in a rock on Mars. Take that, posterity.
But there's good news when I get to work. Yestersol's sequence worked out fine, despite the wacky joint moves we used. Yestersol's focus was on brushing Ebenezer with the RAT; thisol we're following that up by grinding. Leaving an eternal mark on another world -- it's a strange kind of immortality, but I have an inexhaustible appetite for it.
After the grind, we APXS the RAT hole. As a measure of how cold it's getting on Mars, we can APXS at mid-day -- since the APXS works best in the cold, we used to have to wait until late at night to start it. So the warmest part of our day is now about as cold as the coldest part of our day used to be. Poor Spirit. Hang in there, baby, summer's coming. Just a few more months ....
Of course, the colder temperatures, and reduced sun exposure, mean we have less energy to play with. So the RAT's tail gets amputated -- what starts as a three-hour grind (insert Gilligan's Island reference here) is cut to two and a half hours, then to two. Like any of the scientists, the RAT guys' faces fall a little more each time they're cut. I slide over to one of them, Phil Chu, and commiserate. "That's the same thing that used to happen to us all the time on drive sols -- it starts out as a four-hour drive and you end up with fifteen minutes." Phil laughs. "Ah, it's not a problem," he says. And he's probably right, at that -- Ebenezer's a soft rock; even with only two hours to run, the RAT will take a good chunk out of it.
I'll never have kids, but I'll make an indelible hole in a rock on Mars. Take that, posterity.
2009-08-26
Spirit Sol 230
"Let me tell you, this target sucks," Chris exclaims. Truly, this target is in a very odd spot. The flight software will happily place the APXS and MB on it, but it generates errors when you try to place the RAT or MI. Which is supposed to be impossible -- if you can get there with one tool, you can get there with all of them.[1] Yet we've found an exception to the rule. Still stranger, the software will happily place the MI all around the target (which we did the other sol) -- just not on the target itself. I'd look into that if I had the time.
Still, our explorations here continue to go well. The scientists have gained enough confidence in the instrument placements here that they've cut down the MIs from 5-stacks to 3-stacks. That is, instead of taking a series of five images at each position, we're taking just three. The more images you take, the more likely it is one will be in focus; thus, shorter stacks indicate more confidence (or less importance, or tighter downlink). We've gone as high as eleven. Insert Spinal Tap joke here.
There are limits to their confidence, though. Since the APXS doors recently didn't open fully when we tried to open them on a rock target, they've asked us to open the APXS on the CCT instead. The CCT, or Compositional Calibration Target, is a spot on the rover's own body, just above the space the arm stows into. As its name implies, it's used to help calibrate the MB and APXS -- we know what it's made of, so taking readings of it helps us interpret readings of unknown stuff. And since it's a hard and accessible surface, we can also open the APXS doors on it.
But doing so requires a more-than-usual amount of clearance under the rover. The HAZCAMs can't see that area, so Chris asks me to look back at imagery from previous sols to see if we have room. He tells me about some weird trick Frank uses for this, which basically amounts to an abuse of the IDD workspace display[2], but it doesn't seem to work for me and I quickly lose patience. Instead, I do what I usually do in this situation -- bring up the terrain mesh built from the old imagery, and slide the rover around until the simulated camera view looks like the real one. This isn't precise, but it's easy and quick -- and in a case like this one, where it turns out there's nothing of consequence under the rover that could possibly be a problem, it turns out to be good enough.
One problem solved.
Chris is solving another one. There are basically two ways to move the arm. One way is called a joint move: tell one or more of its five joints what position you want it in. The other way is called a Cartesian move: give it the three-dimensional (i.e., Cartesian) coordinates of a point in space and tell it to put the current tool there. A very useful variant on this second way can also be used to move the arm in so-called "tool frame," a coordinate system centered on the current tool. Z is "down" in this frame, so you can place the tool 10cm above the target, then tell the arm to move 10cm "down" to place the tool on the target. (Actually, we normally tell it to move 11cm "down" in this case, to account for uncertainty in the terrain mesh and the arm's own behavior, but never mind that.)
We mostly use Cartesian moves, and RSVP has more facilities for using Cartesian moves than joint moves, because the original plan was to use Cartesian moves all the time. But internally, the IDD flight software converts Cartesian moves into joint moves, and there are some cases it can't convert -- cases like the one that's biting us thisol. We routinely avoid this problem by using a joint move to get near the desired position, then a Cartesian move to get to exactly the right position. (We'd just use joint moves all the time, except that RSVP doesn't make that easy to do; also, Cartesian moves result in easier-to-read sequences.) Chris tries that trick, but it doesn't work, so he just gives up and does it the hard way, computing the needed joint angles and plugging them into RSVP.
Let me tell you, this target sucks.
Footnotes:
[1] Not true, and I'm not sure now why I ever thought that.
[2] A technique now called "Hartman Localization," a clever use of a couple of RSVP features. You start with an old terrain mesh covering an area the rover has since driven into; you know the rover is now somewhere in that mesh, but you don't know exactly where. Then you load in a second mesh, a current one, which is attached to the simulated rover. Then you can slide the simulated rover around until the two meshes match up, and that tells you where the rover actually is in terms of the old mesh. Having done that, you can examine, for instance, what's near the rover that you can't see from the current position (because, say, the rover's own structure now blocks its view).
Still, our explorations here continue to go well. The scientists have gained enough confidence in the instrument placements here that they've cut down the MIs from 5-stacks to 3-stacks. That is, instead of taking a series of five images at each position, we're taking just three. The more images you take, the more likely it is one will be in focus; thus, shorter stacks indicate more confidence (or less importance, or tighter downlink). We've gone as high as eleven. Insert Spinal Tap joke here.
There are limits to their confidence, though. Since the APXS doors recently didn't open fully when we tried to open them on a rock target, they've asked us to open the APXS on the CCT instead. The CCT, or Compositional Calibration Target, is a spot on the rover's own body, just above the space the arm stows into. As its name implies, it's used to help calibrate the MB and APXS -- we know what it's made of, so taking readings of it helps us interpret readings of unknown stuff. And since it's a hard and accessible surface, we can also open the APXS doors on it.
But doing so requires a more-than-usual amount of clearance under the rover. The HAZCAMs can't see that area, so Chris asks me to look back at imagery from previous sols to see if we have room. He tells me about some weird trick Frank uses for this, which basically amounts to an abuse of the IDD workspace display[2], but it doesn't seem to work for me and I quickly lose patience. Instead, I do what I usually do in this situation -- bring up the terrain mesh built from the old imagery, and slide the rover around until the simulated camera view looks like the real one. This isn't precise, but it's easy and quick -- and in a case like this one, where it turns out there's nothing of consequence under the rover that could possibly be a problem, it turns out to be good enough.
One problem solved.
Chris is solving another one. There are basically two ways to move the arm. One way is called a joint move: tell one or more of its five joints what position you want it in. The other way is called a Cartesian move: give it the three-dimensional (i.e., Cartesian) coordinates of a point in space and tell it to put the current tool there. A very useful variant on this second way can also be used to move the arm in so-called "tool frame," a coordinate system centered on the current tool. Z is "down" in this frame, so you can place the tool 10cm above the target, then tell the arm to move 10cm "down" to place the tool on the target. (Actually, we normally tell it to move 11cm "down" in this case, to account for uncertainty in the terrain mesh and the arm's own behavior, but never mind that.)
We mostly use Cartesian moves, and RSVP has more facilities for using Cartesian moves than joint moves, because the original plan was to use Cartesian moves all the time. But internally, the IDD flight software converts Cartesian moves into joint moves, and there are some cases it can't convert -- cases like the one that's biting us thisol. We routinely avoid this problem by using a joint move to get near the desired position, then a Cartesian move to get to exactly the right position. (We'd just use joint moves all the time, except that RSVP doesn't make that easy to do; also, Cartesian moves result in easier-to-read sequences.) Chris tries that trick, but it doesn't work, so he just gives up and does it the hard way, computing the needed joint angles and plugging them into RSVP.
Let me tell you, this target sucks.
Footnotes:
[1] Not true, and I'm not sure now why I ever thought that.
[2] A technique now called "Hartman Localization," a clever use of a couple of RSVP features. You start with an old terrain mesh covering an area the rover has since driven into; you know the rover is now somewhere in that mesh, but you don't know exactly where. Then you load in a second mesh, a current one, which is attached to the simulated rover. Then you can slide the simulated rover around until the two meshes match up, and that tells you where the rover actually is in terms of the old mesh. Having done that, you can examine, for instance, what's near the rover that you can't see from the current position (because, say, the rover's own structure now blocks its view).
2009-08-25
Spirit Sol 229
Amazingly, it worked. I don't know if we're better than I think we are or if we just dodged a bullet this time, but it worked. There's no word yet on whether the MIs were in focus -- we've just got the thumbnails, not the full images -- but there's no IDD fault.
Phew.
So we worked around the terrain mesh problem yestersol, but the problem is still there. Indeed, if anything, we've taken a step backward: Chris is going to have to redo his analysis of it, because his previous analysis was performed using a version of RSVP that incorrectly transformed site to rover coordinates[1]. So not only do we still have the problem, we know even less about it than we thought we did.
I've come in early to check on yestersol's success and also to meet with a couple of reporters from Aviation Week. Aviation Week is going to run a story on MER, and they want to include a wealth of 3-D images illustrating what we've found and how we run the mission. In particular, they're interested in RSVP.
Frank's the artist of the group, and as such he's the best person for them to meet with. But he's leaving on vacation and hasn't packed yet, so he asks me to take care of them. They're just going to need to understand what RSVP is, and what its capabilities are, he tells me. I can handle that.
Only it turns out they've already met with people and they know all that already. What they need is cool screen shots illustrating how we've used RSVP, particularly in the second half of the mission. Preferably artsy stuff.
I can't handle that.
Not that I don't try. What we settle on, after half an hour of fumbling around, is taking a series of screen shots that communicate a sense of what they're after, without actually being what they're after. We email these to Frank, who will make versions of them that actually look cool. When he gets back from vacation. I just hope I haven't wasted their time and put them off the whole idea.
Sigh. Some days I feel useless.
As they're leaving, they catch sight of what Chris is working on. He's looking up at the rover from in front and below, as it reaches out its arm to explore the world before it. "That's perfect!" one of the reporters exclaims. "Can we get a shot of that? Wow, the longer I hang around here, the more cool stuff I see." He should try working here.
Thisol, of course, we continue prodding Ebenezer. I miss out on a lot when I'm not working as RP-1 -- stuff like, why are we at this particular rock instead of another? In this case, I happen to overhear Steve Squyres explaining it to someone: Ebenezer is the unaltered rock they're comparing Clovis to. But Steve's way of putting it is more entertaining: "Ebenezer is whatever Clovis was before whatever happened to it happened to it."
Thisol's exploration turns out to be fairly simple, at least as compared to yestersol, and they don't change their minds about what they want at the last minute, which always helps. This leaves me with time to follow up with Jim Erickson -- who, in case I haven't mentioned this, is now the project manager (Richard Cook moved on). Yesterday he asked me if I had a minute, and I told him no -- I really didn't. "When you have the time," he said. I have the time today, so when I spot him I ask what he wanted.
"You need to come to my office," he says. We head out to the elevator, and he turns around and says, "It's a good thing." He punches the "up" button. While we wait for the elevator, he muses, "Nobody ever got fired 'when you have the time.'"
So we go up to his office and close the door and sit down. I'm getting an award -- it's a JPL thing called a SPOT award, which is basically a pat on the back plus a small amount of money (minus taxes). This one is for "outstanding performance as a Rover Planner ... and in the continuous improvement of the sequence generation and validation software ...."
It was initiated by Arthur Amador ("and I heartily endorsed it and sent it on," Jim adds). Andy Mishkin and Brian Cooper were the ones who hired me onto the project in the first place, and Arthur was the one who (albeit under pressure from Brian) selected me as a rover driver. He was taking a chance on me when he did it, so it's been particularly important to me that I not let him down.
Jim makes me a photocopy of the award form. "This must be one of the best parts of your job," I say to kill time as he navigates the photocopier's needlessly complex menus. "Yeah," he says. "As project manager, you're always having to tell people, 'Cut your budget, do it faster.' You rarely get to say 'Good job.'" He hands me the photocopy and the check. "Good job," he says.
The award's not much, in itself. But then, it doesn't need to be, especially when it comes at the right time.
Some days I feel useless. But not today.
Footnotes:
[1] It took me a while to wrap my head around the plethora of coordinate frames on MER. Some things as seemingly simple as locating a point in the world -- just asking a question like "where am I?" -- turn out to be more subtle and complex than I'd previously considered.
So. As we all remember from high-school geometry, you can designate any point with three numbers -- say, one representing how far north/south the point is, one representing how far east/west the point is, and one representing how far up/down the point is. But those numbers have to be measured relative to some starting point, and for different purposes you want to use a different starting point.
For most purposes, on MER, we designate points in the world -- for example, drive targets, or science targets of interest -- relative to a "site frame," which we periodically reset. Resetting it makes all your old targets useless because it restarts the numbering at zero in a new place, but this is a more useful thing to do than you might think: when you've driven far enough (usually tens or hundreds of meters) from the last place you reset the site frame, all the numbers for designating a new point become annoyingly large, and the points you might have designated before have been left behind anyway.
For some purposes, though, we use another coordinate system called "rover frame," which is centered on a certain point on the rover body. As the rover moves around in the world, it sort of carries that "rover frame" with it. So, for example, in rover frame, the numbers (1, 0, 0) might designate the point exactly one meter in front of the rover, wherever the rover happens to be.
Coordinate frames are also oriented differently: site frame is oriented so that it aims north, while rover frame is oriented so that it pokes out the front of the rover, no matter how the rover is aimed or tilted.
Now, you sometimes need to refer to the same point using two different coordinate frames -- for example, to satisfy two different pieces of software that have different needs -- and transforming between them takes a bit of matrix math. Here, the problem was that the points Chris was looking at were picked out in site frame (which is the usual way to do it) but what mattered in this case was how the IDD flight software referred to them, which was in rover frame. Chris was using RSVP to transform one set of numbers into the other, but at the time there was a bug in how RSVP did this, which spoiled his work.
Driving a rover on Mars can be complicated.
Phew.
So we worked around the terrain mesh problem yestersol, but the problem is still there. Indeed, if anything, we've taken a step backward: Chris is going to have to redo his analysis of it, because his previous analysis was performed using a version of RSVP that incorrectly transformed site to rover coordinates[1]. So not only do we still have the problem, we know even less about it than we thought we did.
I've come in early to check on yestersol's success and also to meet with a couple of reporters from Aviation Week. Aviation Week is going to run a story on MER, and they want to include a wealth of 3-D images illustrating what we've found and how we run the mission. In particular, they're interested in RSVP.
Frank's the artist of the group, and as such he's the best person for them to meet with. But he's leaving on vacation and hasn't packed yet, so he asks me to take care of them. They're just going to need to understand what RSVP is, and what its capabilities are, he tells me. I can handle that.
Only it turns out they've already met with people and they know all that already. What they need is cool screen shots illustrating how we've used RSVP, particularly in the second half of the mission. Preferably artsy stuff.
I can't handle that.
Not that I don't try. What we settle on, after half an hour of fumbling around, is taking a series of screen shots that communicate a sense of what they're after, without actually being what they're after. We email these to Frank, who will make versions of them that actually look cool. When he gets back from vacation. I just hope I haven't wasted their time and put them off the whole idea.
Sigh. Some days I feel useless.
As they're leaving, they catch sight of what Chris is working on. He's looking up at the rover from in front and below, as it reaches out its arm to explore the world before it. "That's perfect!" one of the reporters exclaims. "Can we get a shot of that? Wow, the longer I hang around here, the more cool stuff I see." He should try working here.
Thisol, of course, we continue prodding Ebenezer. I miss out on a lot when I'm not working as RP-1 -- stuff like, why are we at this particular rock instead of another? In this case, I happen to overhear Steve Squyres explaining it to someone: Ebenezer is the unaltered rock they're comparing Clovis to. But Steve's way of putting it is more entertaining: "Ebenezer is whatever Clovis was before whatever happened to it happened to it."
Thisol's exploration turns out to be fairly simple, at least as compared to yestersol, and they don't change their minds about what they want at the last minute, which always helps. This leaves me with time to follow up with Jim Erickson -- who, in case I haven't mentioned this, is now the project manager (Richard Cook moved on). Yesterday he asked me if I had a minute, and I told him no -- I really didn't. "When you have the time," he said. I have the time today, so when I spot him I ask what he wanted.
"You need to come to my office," he says. We head out to the elevator, and he turns around and says, "It's a good thing." He punches the "up" button. While we wait for the elevator, he muses, "Nobody ever got fired 'when you have the time.'"
So we go up to his office and close the door and sit down. I'm getting an award -- it's a JPL thing called a SPOT award, which is basically a pat on the back plus a small amount of money (minus taxes). This one is for "outstanding performance as a Rover Planner ... and in the continuous improvement of the sequence generation and validation software ...."
It was initiated by Arthur Amador ("and I heartily endorsed it and sent it on," Jim adds). Andy Mishkin and Brian Cooper were the ones who hired me onto the project in the first place, and Arthur was the one who (albeit under pressure from Brian) selected me as a rover driver. He was taking a chance on me when he did it, so it's been particularly important to me that I not let him down.
Jim makes me a photocopy of the award form. "This must be one of the best parts of your job," I say to kill time as he navigates the photocopier's needlessly complex menus. "Yeah," he says. "As project manager, you're always having to tell people, 'Cut your budget, do it faster.' You rarely get to say 'Good job.'" He hands me the photocopy and the check. "Good job," he says.
The award's not much, in itself. But then, it doesn't need to be, especially when it comes at the right time.
Some days I feel useless. But not today.
Footnotes:
[1] It took me a while to wrap my head around the plethora of coordinate frames on MER. Some things as seemingly simple as locating a point in the world -- just asking a question like "where am I?" -- turn out to be more subtle and complex than I'd previously considered.
So. As we all remember from high-school geometry, you can designate any point with three numbers -- say, one representing how far north/south the point is, one representing how far east/west the point is, and one representing how far up/down the point is. But those numbers have to be measured relative to some starting point, and for different purposes you want to use a different starting point.
For most purposes, on MER, we designate points in the world -- for example, drive targets, or science targets of interest -- relative to a "site frame," which we periodically reset. Resetting it makes all your old targets useless because it restarts the numbering at zero in a new place, but this is a more useful thing to do than you might think: when you've driven far enough (usually tens or hundreds of meters) from the last place you reset the site frame, all the numbers for designating a new point become annoyingly large, and the points you might have designated before have been left behind anyway.
For some purposes, though, we use another coordinate system called "rover frame," which is centered on a certain point on the rover body. As the rover moves around in the world, it sort of carries that "rover frame" with it. So, for example, in rover frame, the numbers (1, 0, 0) might designate the point exactly one meter in front of the rover, wherever the rover happens to be.
Coordinate frames are also oriented differently: site frame is oriented so that it aims north, while rover frame is oriented so that it pokes out the front of the rover, no matter how the rover is aimed or tilted.
Now, you sometimes need to refer to the same point using two different coordinate frames -- for example, to satisfy two different pieces of software that have different needs -- and transforming between them takes a bit of matrix math. Here, the problem was that the points Chris was looking at were picked out in site frame (which is the usual way to do it) but what mattered in this case was how the IDD flight software referred to them, which was in rover frame. Chris was using RSVP to transform one set of numbers into the other, but at the time there was a bug in how RSVP did this, which spoiled his work.
Driving a rover on Mars can be complicated.
2009-08-24
Spirit Sol 228
I'm the only rover driver who hasn't worked on both rovers. Brian and Jeff did most of Spirit's first drive before moving to Opportunity. Eric did the initial IDD checkout sequences, which Frank edited slightly, before moving to Opportunity; and Eric came back for a sol or two. Chris has spent several sols on Opportunity, and John is racking up a few as well. Ashitey, too. Bob never worked on Opportunity as far as I can recall, but he's off the project now.
Which leaves me. But not for long: I have a shift scheduled on Opportunity tomorrow. Technically, I'm a floater, which means in practice that I'm working on both, but it counts.
The only bad news is, I don't know anything about what they're up to or when they expect me to come in. So I go upstairs to the Opportunity room to find out.
"When do you need me tomorrow?" I ask Emily.
"Tomorrow's a restricted sol[1]," she replies. "We don't need a rover planner."
Well, that's just ducky. I guess I won't be working on Opportunity tomorrow, after all. And on the current schedule, I don't get another chance at it for a while.
And Opportunity has cool stuff going on right now, too, as Chris Salvo shows me. They found this weird mudlike stuff -- it looked like rock, but driving over it nearly destroyed much of it -- which they're going to drive back to and examine in detail with the IDD. Nobody knows what this is. One thing is certain, though: I won't be helping them find out.
Ah, well, Spirit's my first love, anyway. While I was away, they finished up at the previous location (where the rover slipped almost double the predicted amount during my last drive -- turns out it's a good thing I shortened it) and then performed a short drive to a new rock called "Ebenezer." The targets on Ebenezer are named for characters from "A Christmas Carol" -- TinyTim, Cratchit, Scrooge, Marley.
We expect to stay at Ebenezer for a while. The scientists like this rock and our power situation is excellent, so we might stay here through solar conjunction[2]. In the meantime, we'll be performing the usual extended exploration campaign -- APXS, MI, MB, RAT-brush, APXS, MI, MB, RAT-grind, APXS, MI, MB, and then maybe do it all over with different targets.
But not all in one sol, of course. Today we're just getting started, unstowing and beginning to poke at the surface. John has the work largely done by the time I get in, so it should be a cakewalk.
But, reminiscent of Ebenezer Scrooge himself, we're haunted by the Ghost of Sols Past. Yestersol they did a touch-and-go, and we discovered in thisol's downlink that the instrument placements very nearly didn't work. The APXS placement, in fact, wouldn't have opened the APXS doors (a requirement for good data) had John not happened to sequence an unusual preload move at the end of the instrument placement.
This looks like the same problem we've seen several times before, where the surface isn't where the images and terrain mesh seem to say it is. John thinks it's nothing to worry about, a combination of the fact that yestersol's images were taken in shadow (meaning they had low contrast), were heavily compressed, and were of a uniform surface. This combination of factors makes it hard for the stereo correlation to find the same features in the left-eye and right-eye images, and therefore it has a harder time figuring out how far away the terrain is. Thisol we're working with less heavily compressed images of a less uniform surface, so we shouldn't have the problem again.
But Julie's worried about it. She wants the rover to trust its sense of touch more than its sense of sight, by telling it to reach out and touch the surface so it knows where it is. "What would it take to do a MB touch before each instrument placement?" she asks.
John shrugs. "We can do that," he says. "We'll have to redo all the sequencing to use relative moves instead."
"How long will that take?"
He shrugs again. "A couple of hours," he says.
This is designed to make Julie give up on the idea. We're already an hour behind schedule, and nobody likes to slip even later. But she doesn't take the bait. "Okay," she says, "go ahead."
John looks annoyed, but it's not his problem anyway -- it's mine. I pick up the sequence and get to work.
As predicted, the changes take a couple of hours to implement. Then it gets worse. At the walkthrough, they ask for even more changes. By the time all is said and done, we're almost four hours late.
And I'm not really sure we gained anything. I've made a lot of changes under time pressure, which is always risky. If we'd been smart, we'd have weighed that risk against the risk of just leaving the original version of the sequence alone. Instead, we weighed risk against time, which was the wrong tradeoff. By now, we ought to be smarter about this stuff.
As I'm leaving, I can't help but think of that bit from The Princess Bride:
Footnotes:
[1] Because of the difference in the two planets' day lengths, the Martian day appears to rotate through our planning day -- Martian noon is 40 minutes later each Earth day, more or less. When the phasing reaches a point where the sol's downlink (whose timing depends on the Martian-day time seen by a particular rover) will arrive so late in the Earth day that we'll no longer have time to plan the next sol's activities for the rovers, we plan differently: we plan two sols' worth of activities for that rover, every other day.
Planning ahead this way restricts what we can safely do with the rover, though -- we can't plan anything for the second sol that might be unsafe if the first sol goes awry, for instance, since we have to plan them both at the same time -- so these are known as "restricted sols."
Incidentally, because the two rovers are at almost exactly opposite longitudes on Mars, their Mars times are about 12 hours apart, so at most one rover is ever in restricted sols at any particular time.
[2] When the sun will be between us and Mars, making it impossible for us to reliably communicate with the rovers for about two weeks.
Which leaves me. But not for long: I have a shift scheduled on Opportunity tomorrow. Technically, I'm a floater, which means in practice that I'm working on both, but it counts.
The only bad news is, I don't know anything about what they're up to or when they expect me to come in. So I go upstairs to the Opportunity room to find out.
"When do you need me tomorrow?" I ask Emily.
"Tomorrow's a restricted sol[1]," she replies. "We don't need a rover planner."
Well, that's just ducky. I guess I won't be working on Opportunity tomorrow, after all. And on the current schedule, I don't get another chance at it for a while.
And Opportunity has cool stuff going on right now, too, as Chris Salvo shows me. They found this weird mudlike stuff -- it looked like rock, but driving over it nearly destroyed much of it -- which they're going to drive back to and examine in detail with the IDD. Nobody knows what this is. One thing is certain, though: I won't be helping them find out.
Ah, well, Spirit's my first love, anyway. While I was away, they finished up at the previous location (where the rover slipped almost double the predicted amount during my last drive -- turns out it's a good thing I shortened it) and then performed a short drive to a new rock called "Ebenezer." The targets on Ebenezer are named for characters from "A Christmas Carol" -- TinyTim, Cratchit, Scrooge, Marley.
We expect to stay at Ebenezer for a while. The scientists like this rock and our power situation is excellent, so we might stay here through solar conjunction[2]. In the meantime, we'll be performing the usual extended exploration campaign -- APXS, MI, MB, RAT-brush, APXS, MI, MB, RAT-grind, APXS, MI, MB, and then maybe do it all over with different targets.
But not all in one sol, of course. Today we're just getting started, unstowing and beginning to poke at the surface. John has the work largely done by the time I get in, so it should be a cakewalk.
But, reminiscent of Ebenezer Scrooge himself, we're haunted by the Ghost of Sols Past. Yestersol they did a touch-and-go, and we discovered in thisol's downlink that the instrument placements very nearly didn't work. The APXS placement, in fact, wouldn't have opened the APXS doors (a requirement for good data) had John not happened to sequence an unusual preload move at the end of the instrument placement.
This looks like the same problem we've seen several times before, where the surface isn't where the images and terrain mesh seem to say it is. John thinks it's nothing to worry about, a combination of the fact that yestersol's images were taken in shadow (meaning they had low contrast), were heavily compressed, and were of a uniform surface. This combination of factors makes it hard for the stereo correlation to find the same features in the left-eye and right-eye images, and therefore it has a harder time figuring out how far away the terrain is. Thisol we're working with less heavily compressed images of a less uniform surface, so we shouldn't have the problem again.
But Julie's worried about it. She wants the rover to trust its sense of touch more than its sense of sight, by telling it to reach out and touch the surface so it knows where it is. "What would it take to do a MB touch before each instrument placement?" she asks.
John shrugs. "We can do that," he says. "We'll have to redo all the sequencing to use relative moves instead."
"How long will that take?"
He shrugs again. "A couple of hours," he says.
This is designed to make Julie give up on the idea. We're already an hour behind schedule, and nobody likes to slip even later. But she doesn't take the bait. "Okay," she says, "go ahead."
John looks annoyed, but it's not his problem anyway -- it's mine. I pick up the sequence and get to work.
As predicted, the changes take a couple of hours to implement. Then it gets worse. At the walkthrough, they ask for even more changes. By the time all is said and done, we're almost four hours late.
And I'm not really sure we gained anything. I've made a lot of changes under time pressure, which is always risky. If we'd been smart, we'd have weighed that risk against the risk of just leaving the original version of the sequence alone. Instead, we weighed risk against time, which was the wrong tradeoff. By now, we ought to be smarter about this stuff.
As I'm leaving, I can't help but think of that bit from The Princess Bride:
Valerie Max: Think it'll work?
Miracle Max: It would take a miracle!
Footnotes:
[1] Because of the difference in the two planets' day lengths, the Martian day appears to rotate through our planning day -- Martian noon is 40 minutes later each Earth day, more or less. When the phasing reaches a point where the sol's downlink (whose timing depends on the Martian-day time seen by a particular rover) will arrive so late in the Earth day that we'll no longer have time to plan the next sol's activities for the rovers, we plan differently: we plan two sols' worth of activities for that rover, every other day.
Planning ahead this way restricts what we can safely do with the rover, though -- we can't plan anything for the second sol that might be unsafe if the first sol goes awry, for instance, since we have to plan them both at the same time -- so these are known as "restricted sols."
Incidentally, because the two rovers are at almost exactly opposite longitudes on Mars, their Mars times are about 12 hours apart, so at most one rover is ever in restricted sols at any particular time.
[2] When the sun will be between us and Mars, making it impossible for us to reliably communicate with the rovers for about two weeks.
2009-08-19
Spirit Sol 223
So I'm RP-1, bright and shiny at 8 AM. And Art's here, so it's almost like the old days. "How ya doing, Art?" I ask, and he groans, "So good ... if it were any better, I don't know if I'd survive it." So I'm not the only non-morning person around here.
"Are we still driving today?"
"Today we're driving" -- he pauses dramatically -- "maybe one wheel rotation. Hey, don't knock it -- they could take that away from us."
Since I'm here at the right time, as opposed to the time the schedule said, I'm actually present for the SOWG meeting. That's been a long time -- so long, I have to ask Art if they're still having them in the same location. They are, so I head upstairs for that.
This SOWG is easy, since our sol is so easy. They're finished RATting this spot right in front of us and want to RAT another spot near the right front wheel. So all we're doing is turning 30 degrees clockwise and backing up 25cm. There's a little concern that we'll drive over the location we were just RATting before we have a chance to image it, but I model it in RSVP and demonstrate to their satisfaction that we won't be coming anywhere near it.
Of course, nothing is ever that easy, and today's no exception. Since we're on a steep slope, we expect to slip during the drive. The question is, how much? Fortunately, I'm getting better at delegating, so I just ask Rich Petras -- Mobility/IDD support thisol -- to figure it out for me. Between the turn and the drive, we expect to slip about 10cm downhill. RSVP shows that the RAT can still hit a target 10cm further upslope, meaning that the new RAT spot will be reachable even if we slip. I end up cutting the drive slightly, though, from 25cm to 20cm, just to split the difference.
We're holding a press conference today. On the agenda: what Opportunity's been up to, why the scientists care about Spirit again, and news about Opportunity's RAT. Art turns on the TV and starts flipping to the NASA channel, but gets stuck on the Olympics. I'm busy polishing the drive, but the grunts of sympathetic pain behind me keep me amused.
The press conference itself was intelligently done. Opportunity has a problem with its RAT -- it looks like there's a chunk of rock caught in the grinding wheel, which keeps the wheel from rotating. This is a known vulnerability in the design; they can issue low-level motor commands to run the wheel backward, and the obstructing rock should pop right back out.
But if they led the press conference with that, the headlines would read, "MARS MISSION DOOMED: NASA Embarrassed by Failed Science Instrument." And it's all the press would ask about at the end, because they'd get their heads filled up with questions about the RAT and stop paying attention. So they don't do that. They leave the RAT hiccup to the end, and lead with the positive stuff instead. The positive stuff includes Steve Squyres saying Spirit has found the best bedrock yet found at either site. It's exciting because we have altered rock adjacent to unaltered rock -- this gives you a chance to figure out what changed the rock. They also have an astonishing three-frame animation of water-ice clouds moving across the pink Martian sky -- just faint wisps of stuff, but unmistakable. And they have a gorgeous color PANCAM mosaic from Spirit -- the pictures we've been taking the last few sols so I could have an unexpected holiday.
Then they bring up Opportunity's RAT, and sure enough, the press appears to put the matter in its proper perspective. Check that out.
Even though we've been at the hill a long time, we haven't ascended very far -- we're just 9m above "sea level" now. At one point, we were planning to take a path through the hills that would have taken us only about 35m above "sea level," but Larry Soderblom says the plan now is to go all the way to the top of the hill -- 80m or 90m up. Those pictures are going to rock.
Speaking of exciting pictures in our future, Dan Maas is working on another MER video. This one is going to be an IMAX movie, and it's actually been in the works for months. Dan wants the rover to articulate realistically as it drives along -- and who should have software that realistically articulates the rover as it drives along, but yours truly. That, of course, is one of the things RSVP was built for. RSVP can also produce an XML file describing the rover's motion in detail, which is exactly the kind of thing Dan would need. So Justin Wick, an SAP developer who's working with Dan now, asks me to show him how to use RSVP. Which I do, and it's possible -- unlikely, and not a big deal anyway, but possible -- that I'll end up with some kind of credit at the end of the film. "Additional technical assistance provided by ...", or something like that. Heck, maybe they'll make me an associate producer!
Well, let's not get carried away. "Associate Producer" might be an impressive title, but I'll take "Mars Rover Driver" any day.
[Next post: sol 228, August 24.]
Courtesy NASA/JPL-Caltech. A beautiful color PANCAM image showing the RAT work we've been doing on Clovis while sitting here. The full-sized version is even more impressive.
"Are we still driving today?"
"Today we're driving" -- he pauses dramatically -- "maybe one wheel rotation. Hey, don't knock it -- they could take that away from us."
Since I'm here at the right time, as opposed to the time the schedule said, I'm actually present for the SOWG meeting. That's been a long time -- so long, I have to ask Art if they're still having them in the same location. They are, so I head upstairs for that.
This SOWG is easy, since our sol is so easy. They're finished RATting this spot right in front of us and want to RAT another spot near the right front wheel. So all we're doing is turning 30 degrees clockwise and backing up 25cm. There's a little concern that we'll drive over the location we were just RATting before we have a chance to image it, but I model it in RSVP and demonstrate to their satisfaction that we won't be coming anywhere near it.
Of course, nothing is ever that easy, and today's no exception. Since we're on a steep slope, we expect to slip during the drive. The question is, how much? Fortunately, I'm getting better at delegating, so I just ask Rich Petras -- Mobility/IDD support thisol -- to figure it out for me. Between the turn and the drive, we expect to slip about 10cm downhill. RSVP shows that the RAT can still hit a target 10cm further upslope, meaning that the new RAT spot will be reachable even if we slip. I end up cutting the drive slightly, though, from 25cm to 20cm, just to split the difference.
We're holding a press conference today. On the agenda: what Opportunity's been up to, why the scientists care about Spirit again, and news about Opportunity's RAT. Art turns on the TV and starts flipping to the NASA channel, but gets stuck on the Olympics. I'm busy polishing the drive, but the grunts of sympathetic pain behind me keep me amused.
The press conference itself was intelligently done. Opportunity has a problem with its RAT -- it looks like there's a chunk of rock caught in the grinding wheel, which keeps the wheel from rotating. This is a known vulnerability in the design; they can issue low-level motor commands to run the wheel backward, and the obstructing rock should pop right back out.
But if they led the press conference with that, the headlines would read, "MARS MISSION DOOMED: NASA Embarrassed by Failed Science Instrument." And it's all the press would ask about at the end, because they'd get their heads filled up with questions about the RAT and stop paying attention. So they don't do that. They leave the RAT hiccup to the end, and lead with the positive stuff instead. The positive stuff includes Steve Squyres saying Spirit has found the best bedrock yet found at either site. It's exciting because we have altered rock adjacent to unaltered rock -- this gives you a chance to figure out what changed the rock. They also have an astonishing three-frame animation of water-ice clouds moving across the pink Martian sky -- just faint wisps of stuff, but unmistakable. And they have a gorgeous color PANCAM mosaic from Spirit -- the pictures we've been taking the last few sols so I could have an unexpected holiday.
Then they bring up Opportunity's RAT, and sure enough, the press appears to put the matter in its proper perspective. Check that out.
Even though we've been at the hill a long time, we haven't ascended very far -- we're just 9m above "sea level" now. At one point, we were planning to take a path through the hills that would have taken us only about 35m above "sea level," but Larry Soderblom says the plan now is to go all the way to the top of the hill -- 80m or 90m up. Those pictures are going to rock.
Speaking of exciting pictures in our future, Dan Maas is working on another MER video. This one is going to be an IMAX movie, and it's actually been in the works for months. Dan wants the rover to articulate realistically as it drives along -- and who should have software that realistically articulates the rover as it drives along, but yours truly. That, of course, is one of the things RSVP was built for. RSVP can also produce an XML file describing the rover's motion in detail, which is exactly the kind of thing Dan would need. So Justin Wick, an SAP developer who's working with Dan now, asks me to show him how to use RSVP. Which I do, and it's possible -- unlikely, and not a big deal anyway, but possible -- that I'll end up with some kind of credit at the end of the film. "Additional technical assistance provided by ...", or something like that. Heck, maybe they'll make me an associate producer!
Well, let's not get carried away. "Associate Producer" might be an impressive title, but I'll take "Mars Rover Driver" any day.
[Next post: sol 228, August 24.]
Courtesy NASA/JPL-Caltech. A beautiful color PANCAM image showing the RAT work we've been doing on Clovis while sitting here. The full-sized version is even more impressive.
2009-08-17
Spirit Sol 222
I've been scheduled for the last few sols, but there's been no rover motion. We're taking advantage of our good power situation and our excellent location to take a bunch of images and charge the battery. So I keep coming in and being told, "Nothing interesting today; you can go home." And going home.
I came in today mainly to drop off my copy of the Linux Journal that has Frank's and my RSVP article in it. We're duly congratulated.
I'm on as RP-1 tomorrow, and I think we'll actually be doing stuff. But it looks like tomorrow will be a simple sol. All we're doing is a very short drive, not much more than a turn in place, and Ashitey already has a preliminary version ready. After I go over this with him, there's not much more to do but go home. So I do that.
Our issue of the Linux Journal. Not too surprisingly, we made the cover.
I came in today mainly to drop off my copy of the Linux Journal that has Frank's and my RSVP article in it. We're duly congratulated.
I'm on as RP-1 tomorrow, and I think we'll actually be doing stuff. But it looks like tomorrow will be a simple sol. All we're doing is a very short drive, not much more than a turn in place, and Ashitey already has a preliminary version ready. After I go over this with him, there's not much more to do but go home. So I do that.
Our issue of the Linux Journal. Not too surprisingly, we made the cover.
2009-08-11
Spirit Sol 216
I'm RP-1 again. I come in at 8:30, expecting the SOWG meeting at 9:00. But 9:00 rolls around, and no SOWG meeting. In fact, from listening to people talking, it sounds like they had it already.
Turns out the schedule was erroneous. The schedule said the SOWG meeting would be at 9:00, but in fact it was at 8:00, and I'm apparently the only one who read the schedule. Everyone else goes to the SOWG meeting every day, so they know when it's happening, and don't look at the schedule any more.
So I missed it completely. A great way to start your day.
Well, the other news is good. They got usable data from the APXS the other sol after all, Arthur tells me -- the doors were partly open, though they didn't latch. We're going to hold off on uplinking thisol's sequences until we get confirmation that the doors closed, but we're all pretty confident they will.
Thisol we're grinding this rock -- always a fun thing to do. And Ashitey's my RP-2. Thisol goes a lot better than the last time he and I worked together (two sols back), and I like to think it's not only because I'm the guy at the keyboard this time. (It was true in first grade, and it's true today: I need to learn to play better with others.)
The only blight on the day is that we have to cut the RAT grind. The day is constrained on one end by the fact that we can't start IDD work until after noon (it's getting too cold on Mars as Gusev approaches winter) and on the other end by a comm pass. In between, there's just not enough time to do everything the scientists have asked for. We end up cutting some stuff out, and Ashitey and I find clever ways to squeeze down the timing of the other stuff, and in the end they have to cut only 30 minutes out of the grind. It's still a shame, but since 30 minutes translates to only about half a millimeter of depth, the RAT guys don't look all that upset.
And as I'm always saying, if science is happy, I'm happy. And I'm happy.
[Next post: sol 222, August 17.]
Turns out the schedule was erroneous. The schedule said the SOWG meeting would be at 9:00, but in fact it was at 8:00, and I'm apparently the only one who read the schedule. Everyone else goes to the SOWG meeting every day, so they know when it's happening, and don't look at the schedule any more.
So I missed it completely. A great way to start your day.
Well, the other news is good. They got usable data from the APXS the other sol after all, Arthur tells me -- the doors were partly open, though they didn't latch. We're going to hold off on uplinking thisol's sequences until we get confirmation that the doors closed, but we're all pretty confident they will.
Thisol we're grinding this rock -- always a fun thing to do. And Ashitey's my RP-2. Thisol goes a lot better than the last time he and I worked together (two sols back), and I like to think it's not only because I'm the guy at the keyboard this time. (It was true in first grade, and it's true today: I need to learn to play better with others.)
The only blight on the day is that we have to cut the RAT grind. The day is constrained on one end by the fact that we can't start IDD work until after noon (it's getting too cold on Mars as Gusev approaches winter) and on the other end by a comm pass. In between, there's just not enough time to do everything the scientists have asked for. We end up cutting some stuff out, and Ashitey and I find clever ways to squeeze down the timing of the other stuff, and in the end they have to cut only 30 minutes out of the grind. It's still a shame, but since 30 minutes translates to only about half a millimeter of depth, the RAT guys don't look all that upset.
And as I'm always saying, if science is happy, I'm happy. And I'm happy.
[Next post: sol 222, August 17.]
2009-08-10
Spirit Sol 215
This is my first RP-1 sol since I-don't-know-when, and moreover I'm doing it solo -- the scheduling snafu left us no RP-2, though Chris is here as a "floater."
I'm so happy.
It's still shaping up to be a simple sol, a MB-to-APXS tool change. Since we're in this weird out-of-phase part of the daily schedule, they haven't even uplinked yesterday's sequences yet, which means I have time to fix something if it's wrong. But I check them out, and to my surprise I can't find anything wrong with them. There's stuff I'd change in retrospect, but nothing really wrong. So I leave well enough alone.
Anyway, I've got thisol to worry about. It might be simple, but I don't like to procrastinate, so I go ahead and whip out the sequence.
Then we get the sol-213 downlink. Just as no plan ever survives first contact with the enemy, so thisol's plan will not survive first contact with the downlink. The joint angles from sol 213 were very close to the predicted values -- that is, the IDD went just about exactly where we asked it to go -- but the APXS contact switches report no contact and the APXS dust door reports that it's still closed.
Which is mildly bad. The APXS dust doors have to open in order for the scientists to get good data from the instrument. If they're not open, we'll have to redo this observation. We can't redo it on this exact spot, since we're going to RAT it on 214 -- unless we try to modify the sequence before uplinking it a few hours from now -- but that will be OK, since we'll get effectively identical results by just APXSing other parts of the outcrop. We can do that without even driving. And anyway, the doors might be open even though the rover says they're not -- on Opportunity, the switches are flaky, and maybe Spirit's switches are starting to get flaky, too. If so, the APXS observation will be just fine; we'll know when we get the results back later tonight. So it's not the end of the world.
But it does leave us with a puzzle: why did the IDD stop moving? Normally, the IDD will stop moving for one of three reasons: it reaches the commanded position, one of the instrument switches reports contact, or the joints draw more current than allowed (suggesting an unexpected contact). It came close to the commanded position, but didn't quite make it there, so it didn't stop for that reason. The switches report no contact, and the joint currents were well under the limit.
So it shouldn't have stopped. But it did.
In a sense, it doesn't matter. The IDD ended up in the right spot -- more or less -- didn't it? But it's a mystery, and engineers can no more ignore a mystery than they can stop breathing. So Rich Petras and I start trying to figure it out, and we end up sucking in Jessica Brooks and Jeff Favretto and Jeng Yen and some other people. Maybe the APXS contact switches were disabled? No, they're enabled, and anyway we'd see evidence of the switches tripping even if they were disabled, and we don't. Maybe the switches tripped long enough to stop the IDD but then "untripped"? No, we'd still see the temporary trip in the downlink, and we don't. Maybe we don't have all the data from the pass? No, then the data product would be marked as partial, and it isn't.
Oh, hell. We give up and call Bob Bonitz. For once, he doesn't know either, but he does move us forward a step. It looks like we did some calculations incorrectly, and the IDD might think it did reach the commanded position after all.
That's good enough for me. Well, no it isn't, but I have to get back to other work, so it will have to do for now. The other work I have to get back to is related to the fact that the APXS doors aren't known to be open. To avoid contaminating the APXS, we're not supposed to RAT with the APXS doors open. The sol-214 IDD sequence closes the APXS doors before doing the RAT brush, but sometimes the doors open only partially, and then the door-close move doesn't work (you have to open the doors fully before you can close them). So we might be about to RAT with the APXS open. Two hours to uplink ....
The science team decides to take the risk of the doors being open during the RAT brush, so we won't need to change 214 after all. But if the doors are open during the 216 RAT grind, that would be bad. So thisol -- 215 -- we'll have to open the doors fully, so that they'll close when we tell them to. This involves a maneuver that opens the doors on the CCT, a calibration target mounted on the rover's underside.
"Is that going to be a problem?" asks a worried-looking John Grant.
"No," I say cheerfully.
John relaxes instantly. "I love it when he says that," he says.
Changing the sequence takes only minutes. Then I realize that since we're now bringing the IDD up to the rover body, we can take a picture and see whether the doors are open. I throw that in too, for good measure.
And I'm pretty much done for the sol. I start both RP workstations rendering movies for the uplink report and kick back a while. Frank swings by, trailing a huge tour group consisting mainly of Japanese graphic artists and animators -- all SIGGRAPH contacts -- and I tell them a little about what's going on. They're all very polite and thank me profusely, and I kick myself for not remembering how to say "You're welcome" in Japanese. ("Dou-itashi-mashite," dumbass.)
Anticlimactically, I don't get to see the day quite through to the end. Just when the CAM starts, I have to go upstairs for a Change Control Board meeting -- management approval to deliver a slightly updated version of RSVP. Since I can't be in both places at once, Chris helpfully comes downstairs to handle the CAM.
Darn, and I really wanted a challenge.
I'm so happy.
It's still shaping up to be a simple sol, a MB-to-APXS tool change. Since we're in this weird out-of-phase part of the daily schedule, they haven't even uplinked yesterday's sequences yet, which means I have time to fix something if it's wrong. But I check them out, and to my surprise I can't find anything wrong with them. There's stuff I'd change in retrospect, but nothing really wrong. So I leave well enough alone.
Anyway, I've got thisol to worry about. It might be simple, but I don't like to procrastinate, so I go ahead and whip out the sequence.
Then we get the sol-213 downlink. Just as no plan ever survives first contact with the enemy, so thisol's plan will not survive first contact with the downlink. The joint angles from sol 213 were very close to the predicted values -- that is, the IDD went just about exactly where we asked it to go -- but the APXS contact switches report no contact and the APXS dust door reports that it's still closed.
Which is mildly bad. The APXS dust doors have to open in order for the scientists to get good data from the instrument. If they're not open, we'll have to redo this observation. We can't redo it on this exact spot, since we're going to RAT it on 214 -- unless we try to modify the sequence before uplinking it a few hours from now -- but that will be OK, since we'll get effectively identical results by just APXSing other parts of the outcrop. We can do that without even driving. And anyway, the doors might be open even though the rover says they're not -- on Opportunity, the switches are flaky, and maybe Spirit's switches are starting to get flaky, too. If so, the APXS observation will be just fine; we'll know when we get the results back later tonight. So it's not the end of the world.
But it does leave us with a puzzle: why did the IDD stop moving? Normally, the IDD will stop moving for one of three reasons: it reaches the commanded position, one of the instrument switches reports contact, or the joints draw more current than allowed (suggesting an unexpected contact). It came close to the commanded position, but didn't quite make it there, so it didn't stop for that reason. The switches report no contact, and the joint currents were well under the limit.
So it shouldn't have stopped. But it did.
In a sense, it doesn't matter. The IDD ended up in the right spot -- more or less -- didn't it? But it's a mystery, and engineers can no more ignore a mystery than they can stop breathing. So Rich Petras and I start trying to figure it out, and we end up sucking in Jessica Brooks and Jeff Favretto and Jeng Yen and some other people. Maybe the APXS contact switches were disabled? No, they're enabled, and anyway we'd see evidence of the switches tripping even if they were disabled, and we don't. Maybe the switches tripped long enough to stop the IDD but then "untripped"? No, we'd still see the temporary trip in the downlink, and we don't. Maybe we don't have all the data from the pass? No, then the data product would be marked as partial, and it isn't.
Oh, hell. We give up and call Bob Bonitz. For once, he doesn't know either, but he does move us forward a step. It looks like we did some calculations incorrectly, and the IDD might think it did reach the commanded position after all.
That's good enough for me. Well, no it isn't, but I have to get back to other work, so it will have to do for now. The other work I have to get back to is related to the fact that the APXS doors aren't known to be open. To avoid contaminating the APXS, we're not supposed to RAT with the APXS doors open. The sol-214 IDD sequence closes the APXS doors before doing the RAT brush, but sometimes the doors open only partially, and then the door-close move doesn't work (you have to open the doors fully before you can close them). So we might be about to RAT with the APXS open. Two hours to uplink ....
The science team decides to take the risk of the doors being open during the RAT brush, so we won't need to change 214 after all. But if the doors are open during the 216 RAT grind, that would be bad. So thisol -- 215 -- we'll have to open the doors fully, so that they'll close when we tell them to. This involves a maneuver that opens the doors on the CCT, a calibration target mounted on the rover's underside.
"Is that going to be a problem?" asks a worried-looking John Grant.
"No," I say cheerfully.
John relaxes instantly. "I love it when he says that," he says.
Changing the sequence takes only minutes. Then I realize that since we're now bringing the IDD up to the rover body, we can take a picture and see whether the doors are open. I throw that in too, for good measure.
And I'm pretty much done for the sol. I start both RP workstations rendering movies for the uplink report and kick back a while. Frank swings by, trailing a huge tour group consisting mainly of Japanese graphic artists and animators -- all SIGGRAPH contacts -- and I tell them a little about what's going on. They're all very polite and thank me profusely, and I kick myself for not remembering how to say "You're welcome" in Japanese. ("Dou-itashi-mashite," dumbass.)
Anticlimactically, I don't get to see the day quite through to the end. Just when the CAM starts, I have to go upstairs for a Change Control Board meeting -- management approval to deliver a slightly updated version of RSVP. Since I can't be in both places at once, Chris helpfully comes downstairs to handle the CAM.
Darn, and I really wanted a challenge.
2009-08-09
Spirit Sol 214
This is new: Ashitey's RP-1 thisol.
This is also new: there's no RP-1 scheduled for nextersol. But that's a scheduling snafu, one I fix by volunteering to do it myself. (Oh, twist my arm.)
I'll need to be a little late, but Arthur says that won't be a problem. "Tomorrow will just be a simple tool change," he reassures me -- little realizing, I think, that he's disappointing me instead. Hey, if I'm going to be RP-1 again for the first time in what seems like months, I want a damn challenge. But I'll take what I can get.
Thisol is the kind of complicated sol I'm lusting for. We're RATting a spot that we'll then investigate with the MB. But there's another issue: the sol-212 MI images we took appear to be out of focus, so we want to redo them thisol. Now, stay with me. The lowest -- that is, closest-to-rock -- MI images appeared to be most nearly in focus. And Ashitey's plan for thisol is to redo the stacks[1] using a technique that will start farther away from the rock. Which will make their focus worse, not better. Which is a complete waste of time, energy, and downlink data volume. I can't seem to communicate this concept to Ashitey to save my life, so it goes up like that.[2] Oy.
But Ashitey and I have worse problems. Thisol's IDD work requires that we move the IDD away from its current position a few times. But because sol 213's sequences haven't executed yet, we don't know exactly where the IDD contacted, so we have to pull some tricks to command the IDD back to its current position during thisol's business. The IDD automatically remembers a single location, so the only way to do this is to use a special command that tells the IDD to put a different tool on the last saved location. And that command doesn't seem to be working, at least not in the simulation. Neither Ashitey nor I can understand why not. It doesn't make sense: we're putting the IDD in the configuration it would have after the change-tool command would execute, then issuing the change-tool command, and the simulation says the command fails. We can't figure out why we would get an error at all, and the message itself isn't very useful.
This is where certain personality differences between me and Ashitey start to be a problem. We like each other a lot, but, well, we're very different. Most relevant, Ashitey's cool with being late, and I'm just not. Ashitey is the epitome of Type B, and I am Type A. No, make that Type A+. Type A+++. You get the picture.
We're not ready for the activity plan approval meeting. "Got an animation for me?" Saina asks. "Just a few minutes," Ashitey reassures her, but the minutes pass and we've made no progress. Saina and the scientists are clearly growing more and more concerned as Ashitey keeps putting them off, "just a few minutes" at a time. An hour passes this way, and I am starting to go insane. We're slipping later and later, and I'm not in control of the situation: Ashitey's sitting in front of the keyboard, not I, and he naturally wants to argue about every idea I have for fixing the situation (not that his -- or, for that matter, my -- ideas are working anyway).
I heroically summon every ounce of self-control I possess, and smile grandly at Ashitey. By itself, that act calms me down a lot.
But not for long. (Long enough to sign a small poster for Arthur C. Clarke, but not much longer.) Another hour goes by, and we're as stuck as we were to start with. At this point I decide to believe that my problem is that I'm not in front of the keyboard, so under the pretense of checking something, I log into the other RP workstation and start working out my ideas directly, rather than arguing over them with Ashitey one at a time. They're still not panning out, but at least I can explore them faster; and I'm driving, which makes me feel better for no good reason.
What we need is a fresh pair of eyes, and luckily we get one. John was working on Opportunity today, and when he moseys downstairs to say howdy I rope him into helping out. He and I look at it a while, and eventually we realize that we're helping the IDD too much. Remember that we're moving the IDD away and then back to where it started, then using the tool-change command to fix up its position more precisely. When we moved the IDD back in, we put it in approximately the configuration it would put itself in after the tool change, thinking that would simplify things for it, but the software can't handle that; it wants to compute its own path to the post-tool-change position, and gets upset if we do the work for it. When we make things "harder" by using the pre-change configuration instead (helped along by another trick with the amusing name of "the guarded move to nowhere"), it works like a charm.
We're three and a half hours late, I've probably destroyed my relationship with Ashitey, the new MIs are going to be in worse focus than the old ones, and hell if I know whether this hacked-up sequence is even going to work.
Did I say I like a challenge?
Can I just have a simple tool change?
Please?
Footnotes:
[1] When you look at something under a microscope on Earth, you look through the eyepiece and twiddle the focus knob until the subject is focused. We can't do that on the rovers because light-time delays would make the knob-twiddling take forever. Instead, our sequence takes a whole "stack" of images -- some above, one at, and some below where we think the right focus distance is. We're pretty good at nailing the best-focus position, but when we miss it, the images taken above and below that position are our record of what happened when we twiddled the focus knob; one of the images is almost always well-focused.
[2] A serious mistake. Yes, we were busy and stressed and running late. There was still no excuse for uplinking a sequence that I really didn't think would correctly implement the science observation. Since Ashitey and I clearly weren't communicating well here, a smarter move would have been to politely involve else in the conversation, someone who might have been better at explaining things to Ashitey (or to me, if I actually was in the wrong).
This is also new: there's no RP-1 scheduled for nextersol. But that's a scheduling snafu, one I fix by volunteering to do it myself. (Oh, twist my arm.)
I'll need to be a little late, but Arthur says that won't be a problem. "Tomorrow will just be a simple tool change," he reassures me -- little realizing, I think, that he's disappointing me instead. Hey, if I'm going to be RP-1 again for the first time in what seems like months, I want a damn challenge. But I'll take what I can get.
Thisol is the kind of complicated sol I'm lusting for. We're RATting a spot that we'll then investigate with the MB. But there's another issue: the sol-212 MI images we took appear to be out of focus, so we want to redo them thisol. Now, stay with me. The lowest -- that is, closest-to-rock -- MI images appeared to be most nearly in focus. And Ashitey's plan for thisol is to redo the stacks[1] using a technique that will start farther away from the rock. Which will make their focus worse, not better. Which is a complete waste of time, energy, and downlink data volume. I can't seem to communicate this concept to Ashitey to save my life, so it goes up like that.[2] Oy.
But Ashitey and I have worse problems. Thisol's IDD work requires that we move the IDD away from its current position a few times. But because sol 213's sequences haven't executed yet, we don't know exactly where the IDD contacted, so we have to pull some tricks to command the IDD back to its current position during thisol's business. The IDD automatically remembers a single location, so the only way to do this is to use a special command that tells the IDD to put a different tool on the last saved location. And that command doesn't seem to be working, at least not in the simulation. Neither Ashitey nor I can understand why not. It doesn't make sense: we're putting the IDD in the configuration it would have after the change-tool command would execute, then issuing the change-tool command, and the simulation says the command fails. We can't figure out why we would get an error at all, and the message itself isn't very useful.
This is where certain personality differences between me and Ashitey start to be a problem. We like each other a lot, but, well, we're very different. Most relevant, Ashitey's cool with being late, and I'm just not. Ashitey is the epitome of Type B, and I am Type A. No, make that Type A+. Type A+++. You get the picture.
We're not ready for the activity plan approval meeting. "Got an animation for me?" Saina asks. "Just a few minutes," Ashitey reassures her, but the minutes pass and we've made no progress. Saina and the scientists are clearly growing more and more concerned as Ashitey keeps putting them off, "just a few minutes" at a time. An hour passes this way, and I am starting to go insane. We're slipping later and later, and I'm not in control of the situation: Ashitey's sitting in front of the keyboard, not I, and he naturally wants to argue about every idea I have for fixing the situation (not that his -- or, for that matter, my -- ideas are working anyway).
I heroically summon every ounce of self-control I possess, and smile grandly at Ashitey. By itself, that act calms me down a lot.
But not for long. (Long enough to sign a small poster for Arthur C. Clarke, but not much longer.) Another hour goes by, and we're as stuck as we were to start with. At this point I decide to believe that my problem is that I'm not in front of the keyboard, so under the pretense of checking something, I log into the other RP workstation and start working out my ideas directly, rather than arguing over them with Ashitey one at a time. They're still not panning out, but at least I can explore them faster; and I'm driving, which makes me feel better for no good reason.
What we need is a fresh pair of eyes, and luckily we get one. John was working on Opportunity today, and when he moseys downstairs to say howdy I rope him into helping out. He and I look at it a while, and eventually we realize that we're helping the IDD too much. Remember that we're moving the IDD away and then back to where it started, then using the tool-change command to fix up its position more precisely. When we moved the IDD back in, we put it in approximately the configuration it would put itself in after the tool change, thinking that would simplify things for it, but the software can't handle that; it wants to compute its own path to the post-tool-change position, and gets upset if we do the work for it. When we make things "harder" by using the pre-change configuration instead (helped along by another trick with the amusing name of "the guarded move to nowhere"), it works like a charm.
We're three and a half hours late, I've probably destroyed my relationship with Ashitey, the new MIs are going to be in worse focus than the old ones, and hell if I know whether this hacked-up sequence is even going to work.
Did I say I like a challenge?
Can I just have a simple tool change?
Please?
Footnotes:
[1] When you look at something under a microscope on Earth, you look through the eyepiece and twiddle the focus knob until the subject is focused. We can't do that on the rovers because light-time delays would make the knob-twiddling take forever. Instead, our sequence takes a whole "stack" of images -- some above, one at, and some below where we think the right focus distance is. We're pretty good at nailing the best-focus position, but when we miss it, the images taken above and below that position are our record of what happened when we twiddled the focus knob; one of the images is almost always well-focused.
[2] A serious mistake. Yes, we were busy and stressed and running late. There was still no excuse for uplinking a sequence that I really didn't think would correctly implement the science observation. Since Ashitey and I clearly weren't communicating well here, a smarter move would have been to politely involve else in the conversation, someone who might have been better at explaining things to Ashitey (or to me, if I actually was in the wrong).
2009-08-08
Spirit Sol 213
But of course I didn't go. Too much moving to do.
"You should have gone," says Chris. He's nursing a hangover, and he's not the only one. Sounds like it was a wild time. Well, having fun isn't really my thing anyway.
This is, of course, all related to the sad fact that the science teams are, for the most part, leaving us. At least they're going out with a bang: Spirit's findings at Gusev are the focus of a special issue of Science magazine, one of the two preeminent science magazines in the world.
So that's cool.
JPL has access to Science online, so Art's flipping through the images. One of the scientists asks what he's doing, and Art says, "Reliving past glory."
Heck with that, I think; we've got plenty of future glory to achieve. Thisol's little chunk of glory will be to finish up yestersol's MB integration on the outcrop, then calibrate the MB and APXS before starting an APXS integration on the rock. It's not terribly complicated, modulo some confusion about how many times we're supposed to calibrate the APXS and whether we can calibrate the two instruments in parallel, and the day goes relatively smoothly.
So smoothly, indeed, that I have some time to entertain a visitor brought in by Justin Wick, one of the SAP developers. The visitor's name is Rupert Scammell; he's an Aussie who ported SAP to Irix -- he's not a JPLer, so this was just for the fun of it, as far as I can tell -- and who is, obviously, a huge fan of the mission. Justin wants me to show Rupert RSVP, so I do, and I talk to him about being a rover driver, and he gives the impression of being suitably impressed.
It's a supremely geeky experience, of course, and at some point I start to feel self-conscious about this. Then I remember that if I weren't a geek, I wouldn't be here. And I shrug it off. It's cool.
"You should have gone," says Chris. He's nursing a hangover, and he's not the only one. Sounds like it was a wild time. Well, having fun isn't really my thing anyway.
This is, of course, all related to the sad fact that the science teams are, for the most part, leaving us. At least they're going out with a bang: Spirit's findings at Gusev are the focus of a special issue of Science magazine, one of the two preeminent science magazines in the world.
So that's cool.
JPL has access to Science online, so Art's flipping through the images. One of the scientists asks what he's doing, and Art says, "Reliving past glory."
Heck with that, I think; we've got plenty of future glory to achieve. Thisol's little chunk of glory will be to finish up yestersol's MB integration on the outcrop, then calibrate the MB and APXS before starting an APXS integration on the rock. It's not terribly complicated, modulo some confusion about how many times we're supposed to calibrate the APXS and whether we can calibrate the two instruments in parallel, and the day goes relatively smoothly.
So smoothly, indeed, that I have some time to entertain a visitor brought in by Justin Wick, one of the SAP developers. The visitor's name is Rupert Scammell; he's an Aussie who ported SAP to Irix -- he's not a JPLer, so this was just for the fun of it, as far as I can tell -- and who is, obviously, a huge fan of the mission. Justin wants me to show Rupert RSVP, so I do, and I talk to him about being a rover driver, and he gives the impression of being suitably impressed.
It's a supremely geeky experience, of course, and at some point I start to feel self-conscious about this. Then I remember that if I weren't a geek, I wouldn't be here. And I shrug it off. It's cool.
2009-08-07
Spirit Sol 212
The switchback drive worked -- we've reached the outcrop, and the scientists are awfully excited about it. John and I get to be the first to IDD it.
This still amazes me. This rock has been there, right in this spot, for four billion years, almost since Mars was born. We're the first people ever to even see it, much less explore it.
We're starting out simply enough. Indeed, thisol is so simple that when I walk in, John tells me, "The sequence is done -- you can go home."
Of course, life on Mars is never quite that simple. Now that we've made it up onto the outcrop, we're oriented a little more toward the sun than we have been in recent sols, so we have a lot more energy to play with. So much energy, indeed, that the batteries will be fully charged and shunting -- "spilling over," thus wasting energy, unless we find a way to use up more. So the science team asks if I can add in another stack of MI images near the existing stack, and I'm only too happy to oblige. (It's always nice to have something moderately creative to do.)
The location they chose for the first MI stack is called "Cochiti," an allusion to the Cochiti pueblo in New Mexico. I Google for a map of the area, find a nearby pueblo named "Jemez," and name the second stack's position that. I know it's not official, but it's damn cool to name things on another planet.
The visiting scientists are leaving us. It's their last weekend here, and some of the younger ones are throwing a wild party at their apartments to say goodbye.
I'm not planning to go, but then one of the scientists, Nicole Spanovich, asks me if I'm going.
"Nah, I'm way too busy moving into my new house."
She looks almost hurt. "You should go," she admonishes me.
"Okay."
I'm so easy.
Courtesy NASA/JPL-Caltech. Persistence pays off. At last, we're ready to start unlocking the secrets of this ancient stone.
This still amazes me. This rock has been there, right in this spot, for four billion years, almost since Mars was born. We're the first people ever to even see it, much less explore it.
We're starting out simply enough. Indeed, thisol is so simple that when I walk in, John tells me, "The sequence is done -- you can go home."
Of course, life on Mars is never quite that simple. Now that we've made it up onto the outcrop, we're oriented a little more toward the sun than we have been in recent sols, so we have a lot more energy to play with. So much energy, indeed, that the batteries will be fully charged and shunting -- "spilling over," thus wasting energy, unless we find a way to use up more. So the science team asks if I can add in another stack of MI images near the existing stack, and I'm only too happy to oblige. (It's always nice to have something moderately creative to do.)
The location they chose for the first MI stack is called "Cochiti," an allusion to the Cochiti pueblo in New Mexico. I Google for a map of the area, find a nearby pueblo named "Jemez," and name the second stack's position that. I know it's not official, but it's damn cool to name things on another planet.
The visiting scientists are leaving us. It's their last weekend here, and some of the younger ones are throwing a wild party at their apartments to say goodbye.
I'm not planning to go, but then one of the scientists, Nicole Spanovich, asks me if I'm going.
"Nah, I'm way too busy moving into my new house."
She looks almost hurt. "You should go," she admonishes me.
"Okay."
I'm so easy.
Courtesy NASA/JPL-Caltech. Persistence pays off. At last, we're ready to start unlocking the secrets of this ancient stone.
2009-08-02
Spirit Sol 207
The news starts off good, at least. No errors on the drive, and we turned as expected for comm.
But where the hell are we? It looks like we have a little bit of outcrop under our wheels, and we'll just need another drive to back up a little. But first we need to know where we are.
What happens next is something we call "localization." You look at pictures from the previous sol -- or earlier, if you have them -- and try to figure out where you are relative to that picture, by comparing it to the new picture. Generally, this is a game of hunting rocks, trying to find the same set of rocks in each image to use as landmarks. "Let's see, if this guy here in this image is this guy over here in that image, then there would have to be a pointy rock over there ... but there isn't ... so maybe that guy there is the same as that guy over there ...." It helps if you know roughly where you should be looking, which we do. This is laborious, but can be fun in its way.
This time it's not working out. There's a clump of rocks right in front of us that should be obvious from the previous images, but hell if we can find them. We stare at the images for at least fifteen minutes, with plenty of false starts but no luck.
More images come in, and one of the scientists takes a look at one and says, "You know, I don't think we moved."
Ah-hah. The reason we weren't able to localize the rover was that we were trying to find a solution near where we were supposed to end up. Instead we look at the area near where we started -- and sure enough, there's the rock clump. We might have gained a whole meter.
As more images and engineering data arrive, they dispel the mystery. Looks like the rover experienced about 66% slip through the first part of the drive (already more than we'd planned), then the slope became so steep that it just couldn't climb any further. The more it tried to climb, the more it slipped. In one case, visodom showed the rover experiencing 125% slip -- the rover tried to step 60cm upslope, and ended up 15cm downslope.
In the process -- and perhaps exacerbating the problem -- the left rear (goalward) wheel lost contact with the surface. When this happens, the middle wheel continues to drive goalward, causing the bogie pair to tilt the rear wheel further from the surface. The slope was already too steep, but having only five wheels to climb with sure didn't help.
"Ray, I'm sorry," says Squyres, "but we're going to have to take the rover away from you."
Not that it's Ray's fault, of course. I had the foresight to warn them yestersol that something like this might happen, but I don't feel better to have been right.
Squyres and Ray don't want us to drive nextersol. Instead they ask us to take some time to come up with a plan. John and I talk about it a while, and work something out. We clearly can't fight our way directly uphill. Instead, we can drive switchback -- find a series of gentler slopes leading uphill, mostly transverse to the goal. After a few minutes of searching, we're able to find a path.
We'd have time to implement and deliver that drive thisol, but by then the planning has already proceeded with the assumption that we won't be driving, and it's too late to change it. And anyway, there's a possible problem with the PMA, which means we can't use it thisol, which means we can't do visodom thisol, and we definitely don't want to do this drive without visodom. So instead we just get a jump on the next sol, building the sequences now; we'll execute them a sol later.
We show the switchback plan to Ray, and he nods approval. He doesn't mind that it might take us two or three sols to get back uphill to Clovis. "It's going to be worth it," he says. "This outcrop is gonna tell all." Squyres emphatically agrees: "We drove three kilometers to get to this outcrop."
[Next post: sol 212, August 7.]
But where the hell are we? It looks like we have a little bit of outcrop under our wheels, and we'll just need another drive to back up a little. But first we need to know where we are.
What happens next is something we call "localization." You look at pictures from the previous sol -- or earlier, if you have them -- and try to figure out where you are relative to that picture, by comparing it to the new picture. Generally, this is a game of hunting rocks, trying to find the same set of rocks in each image to use as landmarks. "Let's see, if this guy here in this image is this guy over here in that image, then there would have to be a pointy rock over there ... but there isn't ... so maybe that guy there is the same as that guy over there ...." It helps if you know roughly where you should be looking, which we do. This is laborious, but can be fun in its way.
This time it's not working out. There's a clump of rocks right in front of us that should be obvious from the previous images, but hell if we can find them. We stare at the images for at least fifteen minutes, with plenty of false starts but no luck.
More images come in, and one of the scientists takes a look at one and says, "You know, I don't think we moved."
Ah-hah. The reason we weren't able to localize the rover was that we were trying to find a solution near where we were supposed to end up. Instead we look at the area near where we started -- and sure enough, there's the rock clump. We might have gained a whole meter.
As more images and engineering data arrive, they dispel the mystery. Looks like the rover experienced about 66% slip through the first part of the drive (already more than we'd planned), then the slope became so steep that it just couldn't climb any further. The more it tried to climb, the more it slipped. In one case, visodom showed the rover experiencing 125% slip -- the rover tried to step 60cm upslope, and ended up 15cm downslope.
In the process -- and perhaps exacerbating the problem -- the left rear (goalward) wheel lost contact with the surface. When this happens, the middle wheel continues to drive goalward, causing the bogie pair to tilt the rear wheel further from the surface. The slope was already too steep, but having only five wheels to climb with sure didn't help.
"Ray, I'm sorry," says Squyres, "but we're going to have to take the rover away from you."
Not that it's Ray's fault, of course. I had the foresight to warn them yestersol that something like this might happen, but I don't feel better to have been right.
Squyres and Ray don't want us to drive nextersol. Instead they ask us to take some time to come up with a plan. John and I talk about it a while, and work something out. We clearly can't fight our way directly uphill. Instead, we can drive switchback -- find a series of gentler slopes leading uphill, mostly transverse to the goal. After a few minutes of searching, we're able to find a path.
We'd have time to implement and deliver that drive thisol, but by then the planning has already proceeded with the assumption that we won't be driving, and it's too late to change it. And anyway, there's a possible problem with the PMA, which means we can't use it thisol, which means we can't do visodom thisol, and we definitely don't want to do this drive without visodom. So instead we just get a jump on the next sol, building the sequences now; we'll execute them a sol later.
We show the switchback plan to Ray, and he nods approval. He doesn't mind that it might take us two or three sols to get back uphill to Clovis. "It's going to be worth it," he says. "This outcrop is gonna tell all." Squyres emphatically agrees: "We drove three kilometers to get to this outcrop."
[Next post: sol 212, August 7.]
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