Opportunity experienced a disturbing failure this weekend: her IDD failed to deploy. We talked about it this weekend long enough to rule out a sequencing error, which meant we shouldn't try to bring in the normal uplink team to try to fix it and salvage the IDD work. It's possible we would have tried to get the right people together, but it was Thanksgiving, and many people were out of town, and so on. And these days we don't engage in heroics. So we let it go until Monday.
Now it's Monday, and it's not immediately clear what we should do about this, because it's not immediately clear what the failure is. We know we got a tiny amount of motion followed by a motor stall, but why? Eric Baumgartner's (well-educated) guess is that we've simply lost a small amount of knowledge as to the position of the IDD. As a result, when the IDD tried to go to the commanded position as part of its unstow routine, it actually failed to get the IDD off of the little hook it stows itself on, and then it couldn't rotate itself away from the hook. This hypothesis has some confirmation in some image analysis Paolo performed, which may show a tiny discrepancy in the arm's position after the last time we stowed it.
This would be relatively straightforward to solve -- not easy, but not dreadfully bad. We'd have to figure out where the arm actually is, then manually guide it through the unstow routine, at which point we'd be able to recalibrate the IDD by driving each of the joints against its hardstop. We might also need to repeat the "Martian Tai Chi" routine that recalibrates the camera models, so that the IDD and the cameras would be in agreement. It would be a long, slow process -- maybe a week or two, all put together -- but in the end we'd be as good as new.
But Eric's explanation isn't the only one that fits the observed facts. Ashitey fears there's something worse going on. One of the actuators in the testbed rover has started to fail, and it stalls out in pretty much the same way as we've just observed Opportunity's joint motor stall. If this is what's going on, it means the IDD has become unreliable -- every once in a while, our IDD work might randomly fail in this way. That would introduce a severe, somewhat random penalty into all IDD work.
With the testbed rover's IDD, the failures are merely annoying; repeat the failed command, and it usually works the second try. If Opportunity's IDD is indeed failing in this way, that means we have an occasional one-sol penalty to look forward to; probably nothing worse than that (though that would be unpleasant). But it could be worse still: the actuator might simply have failed permanently. And if that's what happened, a large fraction of Opportunity's scientific potential just disappeared forever.
There are other possible explanations, too, with varying degrees of benignity. Erickson wants the full-up anomaly investigation, and the right guy to do that is Ashitey. But Ashitey's RP-1 on Spirit today, which would leave him precious little time for something like that. So he and I switch places -- he heads up the investigation, and I go back to Spirit.
Which means I'm driving today -- driving to Miami. (I try to remember not to leave the left turn signal on.) This drive is reasonably simple, snaking around a few rocks before heading more or less straight toward Miami. Well, not quite Miami -- Coral Gables. See, I didn't have an exact target for Miami, just picked a spot in the neighborhood, and Coral Gables is a Miami suburb ....
Maybe you had to be there.
If all goes well, we'll cover a third to a half of the distance to Miami in this drive. (Maybe we'll stop for the night at a HoJo's. Sorry, I can't help it.)
I'd seen a birthday card in the Spirit sequencing room last week, but it hadn't registered on me until today. I pick it up and read it. I figured it was for someone on the team. Turns out I was right; it's for the most important member of our team. It's a birthday card for a one-year-old -- our one-year-old, Spirit. (Or maybe that should be a "birthsol" card, but I'm not picky.) From the nice (and clever) folks at unmannedspaceflight.com.
I love it. We should make them Spirit's godparents or something.
[Next post: sol 680, December 1.]
2010-11-29
2010-11-27
Spirit Sol 676
Thisol should be easy. Spirit's been IDDing a patch of outcrop named "Seminole," on the target "Osceola." (It's coming up on Thanksgiving, and since we did Pilgrim names last year, we're doing American Indian names this year.) And the big science waypoint we've been heading toward has been renamed from "Waypoint" to "Miami." I'm getting a kick out of this, having gone to Seminole High School and all. But I digress.
So all we're doing is repeating the same stuff they did yesterday on Osceola, only we're changing the target to Abiaka (another Seminole chief). Load up those sequences, change the targets and a few sequence IDs, and you're done.
As is so often the case, it's not that simple. Abiaka unfortunately turns out to be a little too vertical (strictly speaking, Abiaka is a too-vertical normal to a too-horizontal rock surface) -- a problem because the IDD gets confused when you ask it to move straight up and down. That has to do with the target being too close to a wrist-flip condition, where the IDD could choose almost equally well between two different wrist configurations, and if conditions on Mars vary only slightly from the predicts, it could change its mind in the middle and decide it can't do what we want.
The remedy for this is known but tedious: tweak the angle of the target, so that it's tilted slightly away from vertical, until the simulation says you've gone far enough. What complicates this is that we can't tilt the normal too far, or the RAT brushing won't work. Also making it more complex is that John's having his shadow, Ashley, handle the IDD sequence, and while she generally knows what she's doing, she's still new to this and somewhat slow at it.
Oy. Well, it takes forever, but it gets done, and that's what matters.
[Next post: sol 678, November 29.]
So all we're doing is repeating the same stuff they did yesterday on Osceola, only we're changing the target to Abiaka (another Seminole chief). Load up those sequences, change the targets and a few sequence IDs, and you're done.
As is so often the case, it's not that simple. Abiaka unfortunately turns out to be a little too vertical (strictly speaking, Abiaka is a too-vertical normal to a too-horizontal rock surface) -- a problem because the IDD gets confused when you ask it to move straight up and down. That has to do with the target being too close to a wrist-flip condition, where the IDD could choose almost equally well between two different wrist configurations, and if conditions on Mars vary only slightly from the predicts, it could change its mind in the middle and decide it can't do what we want.
The remedy for this is known but tedious: tweak the angle of the target, so that it's tilted slightly away from vertical, until the simulation says you've gone far enough. What complicates this is that we can't tilt the normal too far, or the RAT brushing won't work. Also making it more complex is that John's having his shadow, Ashley, handle the IDD sequence, and while she generally knows what she's doing, she's still new to this and somewhat slow at it.
Oy. Well, it takes forever, but it gets done, and that's what matters.
[Next post: sol 678, November 29.]
2010-11-19
Opportunity Sol 649 (Spirit Sol 668)
Meanwhile, on the other side of the planet ... Opportunity is still skirting the rim of Erebus Crater, making her way to the potential entry point we can see from orbital data. Thisol's plan is to finish up a little IDD work, then drive about 50m -- mostly along outcrop -- toward a flat patch of outcrop we can see in the distance.
This plan is complicated by the fact that the flat patch of outcrop isn't so flat. Looking at it in stereo, we realize that it's actually a somewhat steep face, rising about 50cm over less than 2m. (The fact that the outcrop seems to have some delta-Z makes me think the science team might be interested in it, as it might provide some layered rock to examine. Cooper, ever eager to get moving, is comically reluctant to point this out to them, but I do it anyway.) The ends of the patch are still relatively flat, though, so we decide to aim toward those instead.
Our drive sequence is further complicated by the fact that we're heading at about 180, but need to turn for comm to about 115 -- a large counterclockwise turn, problematic on this vehicle because of the stuck right-front steering actuator. If we knew in advance what our heading would be for the comm turn, that would make it a lot easier to sequence. But we don't, because toward the end there's a slight change in direction: we'll be headed either about 175 or 185 when the time-of-day limit hits. And the only tool we have to make the sequence conditional on the vehicle's yaw gives awkward results around 180, because it gives its answers in the range of -180 to +180 (actually -pi to +pi, since it's in radians) -- nothing we can't sequence around, it's just one more damn thing.
All this still wouldn't be too bad, if Cooper or I were driving. But we decided to let Paolo do it, since he needs the experience. He actually handles it really well, making good decisions and so on. The only problem is that he's still somewhat new, and therefore somewhat slow, and this is a complicated sol, and, well ... it takes a long time. I sit with him pretty much the whole time and strive to stay cheerful and positive. Add that to the list of challenges.
Oh, but we're not through yet. Because I'd been sitting with Paolo, I hadn't had a chance to closely examine Brian's IDD sequence. During the CAM, I discover that the MI poker gets awfully close to a rock during a lateral move. There's less than 1cm of clearance in the prediction, which is within our error budget. Luckily for me, Ken Herkenhoff -- the MI PI, basically the designer and builder and owner of the instrument -- is sitting in the room. (He's normally one of the remote scientists, but is out here to participate in training the new crop.) So I put the CAM on hold, show Ken the situation, and ask his advice.
Now, the MI poker has a bit of spring steel near its base, allowing it to flex safely in just such circumstances as these. And the simulation does show that we have clearance, albeit not much clearance. What's more, we're first touching the surface near the potential contact point, so any error about the location of that point will likely be accounted for -- if our imagery is misleading about that, it should be misleading in the same way about the nearby spot we'll touch, and the sequencing is relative to the touched location, so the error will effectively magically disappear. All this taken into account, Ken's comfortable with proceeding as planned, so we go ahead. (What occurs to me later, as well, is that the simulation we're looking at is actually relative to the 1cm overdrive position -- which aleady accounts for our uncertainty about the terrain -- which means we'll likely have 1cm more clearance than shown. Even better.)
We also realize another place where there's a potential problem. We're in that phase where the Earth-Mars time difference requires us to plan several sols ahead, so we don't yet know the true state of the IDD at the beginning of this sol's sequences -- for the very good reason that that stuff simply hasn't happened yet. And since we're starting (we hope) with the MB in contact with the CCT, we have to disable self-collision checking at the beginning of the sequence in order to allow ourselves to retract the IDD into free space. The problem is, if the planned IDD sequences don't go as predicted, the IDD could start off sol 649 someplace unexpected, and disabling self-collision checking is not what you want to do under those circumstances.
Our solution is to remove the IDD sequence from the bundle -- we'll call in Sunday morning, after we've looked at the data, and we'll send this IDD sequence to the spacecraft only after we know it's done what we expected it to do. This potentially means we'll have to drop the IDD sequence as well as the subsequent drive, since the rover won't drive when the IDD is unstowed -- and it also means we've all got some work to do Saturday night and Sunday morning -- but that's a lot better than risking the IDD.
At long last, we complete the CAM -- and not a moment too soon, as it's been a long and grueling day and we're all getting kind of punchy -- and I realize we've made yet another mistake.
"We're not going to change anything," I say carefully, "but we did screw something up." Normally, our drive sequences detect absent helper sequences, precluding further driving if a helper is missing. (This would mean, for instance, that we were unable to perform a slip check; without that, we don't know whether the vehicle is bogged down, so we don't want to keep trying to drive for tens of meters, making the situation worse.) Our predicted downlink is so poor thisol, however, that we wanted to be sure we'd turn for comm even if one of the helper sequences didn't make it on board. That's rare, but it happens, whether due to a human screw-up somewhere in the process, equipment problems at the DSN stations, or simply because of interference in the long journey of the radio waves from Earth to Mars.
So we pulled a clever trick: during the sequence, we abuse the OK-to-IDD flag -- if a helper is absent and we preclude driving for that reason, we also preclude IDDing. Later, the sequence checks whether we're OK to IDD, and if not, that means a helper must have been missing, so we re-enable driving (and IDDing) so that we can turn for comm.
"What we forgot," I conclude, "is that if you try to drive while driving is precluded -- which we would -- you also get a goal error. And we don't clear that goal error, so the turn for comm still wouldn't happen."
But this bites us only if a helper doesn't make it onto the vehicle -- a rare event -- and it doesn't truly hurt us, it just fails to help us. And at this point on this sol, nobody wants to go back and fix it. So we don't.
[Next post: sol 676, November 27.]
This plan is complicated by the fact that the flat patch of outcrop isn't so flat. Looking at it in stereo, we realize that it's actually a somewhat steep face, rising about 50cm over less than 2m. (The fact that the outcrop seems to have some delta-Z makes me think the science team might be interested in it, as it might provide some layered rock to examine. Cooper, ever eager to get moving, is comically reluctant to point this out to them, but I do it anyway.) The ends of the patch are still relatively flat, though, so we decide to aim toward those instead.
Our drive sequence is further complicated by the fact that we're heading at about 180, but need to turn for comm to about 115 -- a large counterclockwise turn, problematic on this vehicle because of the stuck right-front steering actuator. If we knew in advance what our heading would be for the comm turn, that would make it a lot easier to sequence. But we don't, because toward the end there's a slight change in direction: we'll be headed either about 175 or 185 when the time-of-day limit hits. And the only tool we have to make the sequence conditional on the vehicle's yaw gives awkward results around 180, because it gives its answers in the range of -180 to +180 (actually -pi to +pi, since it's in radians) -- nothing we can't sequence around, it's just one more damn thing.
All this still wouldn't be too bad, if Cooper or I were driving. But we decided to let Paolo do it, since he needs the experience. He actually handles it really well, making good decisions and so on. The only problem is that he's still somewhat new, and therefore somewhat slow, and this is a complicated sol, and, well ... it takes a long time. I sit with him pretty much the whole time and strive to stay cheerful and positive. Add that to the list of challenges.
Oh, but we're not through yet. Because I'd been sitting with Paolo, I hadn't had a chance to closely examine Brian's IDD sequence. During the CAM, I discover that the MI poker gets awfully close to a rock during a lateral move. There's less than 1cm of clearance in the prediction, which is within our error budget. Luckily for me, Ken Herkenhoff -- the MI PI, basically the designer and builder and owner of the instrument -- is sitting in the room. (He's normally one of the remote scientists, but is out here to participate in training the new crop.) So I put the CAM on hold, show Ken the situation, and ask his advice.
Now, the MI poker has a bit of spring steel near its base, allowing it to flex safely in just such circumstances as these. And the simulation does show that we have clearance, albeit not much clearance. What's more, we're first touching the surface near the potential contact point, so any error about the location of that point will likely be accounted for -- if our imagery is misleading about that, it should be misleading in the same way about the nearby spot we'll touch, and the sequencing is relative to the touched location, so the error will effectively magically disappear. All this taken into account, Ken's comfortable with proceeding as planned, so we go ahead. (What occurs to me later, as well, is that the simulation we're looking at is actually relative to the 1cm overdrive position -- which aleady accounts for our uncertainty about the terrain -- which means we'll likely have 1cm more clearance than shown. Even better.)
We also realize another place where there's a potential problem. We're in that phase where the Earth-Mars time difference requires us to plan several sols ahead, so we don't yet know the true state of the IDD at the beginning of this sol's sequences -- for the very good reason that that stuff simply hasn't happened yet. And since we're starting (we hope) with the MB in contact with the CCT, we have to disable self-collision checking at the beginning of the sequence in order to allow ourselves to retract the IDD into free space. The problem is, if the planned IDD sequences don't go as predicted, the IDD could start off sol 649 someplace unexpected, and disabling self-collision checking is not what you want to do under those circumstances.
Our solution is to remove the IDD sequence from the bundle -- we'll call in Sunday morning, after we've looked at the data, and we'll send this IDD sequence to the spacecraft only after we know it's done what we expected it to do. This potentially means we'll have to drop the IDD sequence as well as the subsequent drive, since the rover won't drive when the IDD is unstowed -- and it also means we've all got some work to do Saturday night and Sunday morning -- but that's a lot better than risking the IDD.
At long last, we complete the CAM -- and not a moment too soon, as it's been a long and grueling day and we're all getting kind of punchy -- and I realize we've made yet another mistake.
"We're not going to change anything," I say carefully, "but we did screw something up." Normally, our drive sequences detect absent helper sequences, precluding further driving if a helper is missing. (This would mean, for instance, that we were unable to perform a slip check; without that, we don't know whether the vehicle is bogged down, so we don't want to keep trying to drive for tens of meters, making the situation worse.) Our predicted downlink is so poor thisol, however, that we wanted to be sure we'd turn for comm even if one of the helper sequences didn't make it on board. That's rare, but it happens, whether due to a human screw-up somewhere in the process, equipment problems at the DSN stations, or simply because of interference in the long journey of the radio waves from Earth to Mars.
So we pulled a clever trick: during the sequence, we abuse the OK-to-IDD flag -- if a helper is absent and we preclude driving for that reason, we also preclude IDDing. Later, the sequence checks whether we're OK to IDD, and if not, that means a helper must have been missing, so we re-enable driving (and IDDing) so that we can turn for comm.
"What we forgot," I conclude, "is that if you try to drive while driving is precluded -- which we would -- you also get a goal error. And we don't clear that goal error, so the turn for comm still wouldn't happen."
But this bites us only if a helper doesn't make it onto the vehicle -- a rare event -- and it doesn't truly hurt us, it just fails to help us. And at this point on this sol, nobody wants to go back and fix it. So we don't.
[Next post: sol 676, November 27.]
2010-11-17
Spirit Sol 666
Sol 666: the sol of the Beast. It's a real shame this didn't happen to be Halloween. Maybe thisol should be Martian Halloween.
If there's a Beast involved, he's being awfully good to us. Yestersol's drive went just as expected, a 42m drive -- not much farther than the previous sol, but in a shorter time, thanks to (ahem) remembering to turn on step-skipping during the autonav segment.
Other things are looking up, as well. Our flash volume and data-product count are both still high, but dropping, like the late stages of a Flash Flu. We still need to exercise some restraint; SOWG chair Wendy Calvin proposes alternating atmospheric science sols and geological science sols as a way to reduce flash pressure. Driving is the thing we won't cut -- at least, not entirely, though we do end up shortening the duration once again thisol -- since we have a definite goal and need to make continual progress. The sun is tracking northward in the sky once more, and it isn't going to wait for our little rover, no matter how much she needs and deserves it to.
Yestersol's drive left us about 40m from a small ridge, over which we can just barely see the current science goal (a pile of jumbly black stuff creatively named "Waypoint"). It's 150m away -- we had been thinking it was somewhat closer -- and with a clear, blind-drive-safe 35m to the ridge, we could have made 80m of progress if given three hours to drive (autonav willing). As it is, they cut the drive back to include only the blind part, and maybe a few meters of autonav. We'll make only 40 to 45m.
There's a lot of difference between those two numbers. But if that's all we can afford, that's what we'll do.
[Next post: sol 668 (Opportunity sol 649), November 19.]
Courtesy NASA/JPL-Caltech. The creatively named "Waypoint."
If there's a Beast involved, he's being awfully good to us. Yestersol's drive went just as expected, a 42m drive -- not much farther than the previous sol, but in a shorter time, thanks to (ahem) remembering to turn on step-skipping during the autonav segment.
Other things are looking up, as well. Our flash volume and data-product count are both still high, but dropping, like the late stages of a Flash Flu. We still need to exercise some restraint; SOWG chair Wendy Calvin proposes alternating atmospheric science sols and geological science sols as a way to reduce flash pressure. Driving is the thing we won't cut -- at least, not entirely, though we do end up shortening the duration once again thisol -- since we have a definite goal and need to make continual progress. The sun is tracking northward in the sky once more, and it isn't going to wait for our little rover, no matter how much she needs and deserves it to.
Yestersol's drive left us about 40m from a small ridge, over which we can just barely see the current science goal (a pile of jumbly black stuff creatively named "Waypoint"). It's 150m away -- we had been thinking it was somewhat closer -- and with a clear, blind-drive-safe 35m to the ridge, we could have made 80m of progress if given three hours to drive (autonav willing). As it is, they cut the drive back to include only the blind part, and maybe a few meters of autonav. We'll make only 40 to 45m.
There's a lot of difference between those two numbers. But if that's all we can afford, that's what we'll do.
[Next post: sol 668 (Opportunity sol 649), November 19.]
Courtesy NASA/JPL-Caltech. The creatively named "Waypoint."
2010-11-16
Spirit Sol 665
Ah, heck. We meant to make 60m of progress, and came up with only 37m.
How did this happen? Let's see, autonav imaging takes roughly 3 minutes per 50cm step, which means we should expect to take 20 such steps per hour, or -- oops -- 10m per hour. And we spent two hours on autonav, as predicted, and thus made only about 20m of progress in that time.
Both Ashitey and I were remembering that autonav makes more like 35m per hour. But this is true only when we turn on a feature called "step-skipping." Instead of "image, step, image, step," it does "image, step, step, image, step, step," or even "image, step, step, step, image, step, step, step." Since the "image" part is the slow part, this makes a dramatic improvement in how fast we can drive.
But since this is less safe, since the rover moves farther before taking images of the world around it, it's not the default.
Duh.
Thisol we decide we'll turn on step-skipping.
To make matters worse, we had a poor downlink, and we have more data products on board than we'd like. (We have to worry not only about the total amount of data on the rover but also the number of separate data products.) SOWG chair John Grant proposes cutting the drive short as a way of reducing the generation of new data products until some old ones can be downlinked.
"Nah," I say, "we're not gonna do that."
"But if we don't, the rover will start autodeleting old science products," Emily Eelkema chimes in.
That's what I was waiting for. Since it's been on my mind, I say: "Forget those old MI images! They're history! Let it go! Embrace change!"
They cut the drive short.
Well, it won't be too bad. With step-skipping on, we'll make the same amount of distance as today (about 40m) in the shortened time -- still a decent amount to show for ourselves.
As long as we're changing things in the sequence ... a significant contributor to the drive time is the periodic slip-check sequence. Since it has to invoke visodom, and all the complex 3-D processing that goes along with it, this tends to chew up a lot of duration. What's more, since we're now fairly confident we can make it all the way downhill, most of the original rationale for the slip checks (ensuring we'd be able to make it back to the top of Husband Hill if we got into a bad spot along the way) has disappeared. So I ask Ashitey what he thinks about taking them out.
"Maybe after the Martian-year anniversary," he says. It's next week. "We want both rovers healthy for that."
This is wisdom. I let it go.
Late in the day, Justin Maki points out an article on the Aviation Week Web site. It's something Craig Covault wrote about his recent visit. I didn't realize it at the time, but he was still here for our big discussion about IDDing Hillary.
Emily seems a little worried about the article, but I'm not. "I'm glad he was here for that," I say. "I think it shows us at our best. We had a real concern about a genuinely difficult and novel problem, we took it seriously, we did the analysis we had to do, we proceeded with the right degree of caution -- and in the end, we got the science."
Covault's article is hampered somewhat by the fact that he was on the other end of a teleconference, listening to unfamiliar voices. As a result, some of the details get smudged. But taking that into account, I think he got the big things right: our dedication, our talent, our -- well, damn it, I'm not ashamed to say our brilliance.
Because we're damn good at this. Even if we do forget to turn on step-skipping once in a while.
How did this happen? Let's see, autonav imaging takes roughly 3 minutes per 50cm step, which means we should expect to take 20 such steps per hour, or -- oops -- 10m per hour. And we spent two hours on autonav, as predicted, and thus made only about 20m of progress in that time.
Both Ashitey and I were remembering that autonav makes more like 35m per hour. But this is true only when we turn on a feature called "step-skipping." Instead of "image, step, image, step," it does "image, step, step, image, step, step," or even "image, step, step, step, image, step, step, step." Since the "image" part is the slow part, this makes a dramatic improvement in how fast we can drive.
But since this is less safe, since the rover moves farther before taking images of the world around it, it's not the default.
Duh.
Thisol we decide we'll turn on step-skipping.
To make matters worse, we had a poor downlink, and we have more data products on board than we'd like. (We have to worry not only about the total amount of data on the rover but also the number of separate data products.) SOWG chair John Grant proposes cutting the drive short as a way of reducing the generation of new data products until some old ones can be downlinked.
"Nah," I say, "we're not gonna do that."
"But if we don't, the rover will start autodeleting old science products," Emily Eelkema chimes in.
That's what I was waiting for. Since it's been on my mind, I say: "Forget those old MI images! They're history! Let it go! Embrace change!"
They cut the drive short.
Well, it won't be too bad. With step-skipping on, we'll make the same amount of distance as today (about 40m) in the shortened time -- still a decent amount to show for ourselves.
As long as we're changing things in the sequence ... a significant contributor to the drive time is the periodic slip-check sequence. Since it has to invoke visodom, and all the complex 3-D processing that goes along with it, this tends to chew up a lot of duration. What's more, since we're now fairly confident we can make it all the way downhill, most of the original rationale for the slip checks (ensuring we'd be able to make it back to the top of Husband Hill if we got into a bad spot along the way) has disappeared. So I ask Ashitey what he thinks about taking them out.
"Maybe after the Martian-year anniversary," he says. It's next week. "We want both rovers healthy for that."
This is wisdom. I let it go.
Late in the day, Justin Maki points out an article on the Aviation Week Web site. It's something Craig Covault wrote about his recent visit. I didn't realize it at the time, but he was still here for our big discussion about IDDing Hillary.
Emily seems a little worried about the article, but I'm not. "I'm glad he was here for that," I say. "I think it shows us at our best. We had a real concern about a genuinely difficult and novel problem, we took it seriously, we did the analysis we had to do, we proceeded with the right degree of caution -- and in the end, we got the science."
Covault's article is hampered somewhat by the fact that he was on the other end of a teleconference, listening to unfamiliar voices. As a result, some of the details get smudged. But taking that into account, I think he got the big things right: our dedication, our talent, our -- well, damn it, I'm not ashamed to say our brilliance.
Because we're damn good at this. Even if we do forget to turn on step-skipping once in a while.
2010-11-15
Spirit Sol 664
Many writers and philosophers have spoken of the same idea: life is change, the Eternal Now, you can't step in the same river twice, etc. This concept is logically sound, and I should embrace it. But I have a really hard time with change, especially when the team's changing.
The team's changing.
In a good way; at least nobody I like is leaving. We're bringing in a raft of new scientists, and they're sitting there monitoring the SOWG meeting. It feels weird to be, increasingly, an old-timer on this project that I still think of as the Fresh New Thing. But more, I'm worried that the new scientists are harbingers of unhappy days ahead, days when some of the scientists I've known and liked will be leaving.
I'm sure I'll like the new people, too. But it won't be the same. The moving finger writes, and, having writ, moves on.
We're doing okay on our drive template. Unlike the primary mission, the scientists are actually trying to keep ahead of the line on the graph that shows how far the rover needs to progress each sol. We'll take a hit at Thanksgiving and maybe another at Christmas, but for now we're ahead of the line, even after turning around and going back to spend a week or so IDDing Larry's Bench. Today we're going to make the situation even better, by plowing ahead another sixty meters.
The gaggle of new scientists has brought back a familiar face, Steve Squyres, who's still kvelling about our recent 100m drive (okay, 94m) and looking forward to this one. But, he points out, "You can't slide anything past this uplink team -- even if you try to blow past something interesting, they'll make you turn around and go back!"
Maybe I should figure out a way to cow the new scientists now, before they can develop a troublesome attitude. Change can also be seen as an opportunity, of course.
The team's changing.
In a good way; at least nobody I like is leaving. We're bringing in a raft of new scientists, and they're sitting there monitoring the SOWG meeting. It feels weird to be, increasingly, an old-timer on this project that I still think of as the Fresh New Thing. But more, I'm worried that the new scientists are harbingers of unhappy days ahead, days when some of the scientists I've known and liked will be leaving.
I'm sure I'll like the new people, too. But it won't be the same. The moving finger writes, and, having writ, moves on.
We're doing okay on our drive template. Unlike the primary mission, the scientists are actually trying to keep ahead of the line on the graph that shows how far the rover needs to progress each sol. We'll take a hit at Thanksgiving and maybe another at Christmas, but for now we're ahead of the line, even after turning around and going back to spend a week or so IDDing Larry's Bench. Today we're going to make the situation even better, by plowing ahead another sixty meters.
The gaggle of new scientists has brought back a familiar face, Steve Squyres, who's still kvelling about our recent 100m drive (okay, 94m) and looking forward to this one. But, he points out, "You can't slide anything past this uplink team -- even if you try to blow past something interesting, they'll make you turn around and go back!"
Maybe I should figure out a way to cow the new scientists now, before they can develop a troublesome attitude. Change can also be seen as an opportunity, of course.
2010-11-13
Spirit Sol 662
This was supposed to be an easy sol -- just an IDD tool change, a sequence I could crank out in a couple of minutes. It turns out to be even easier than that -- no RP sequences at all.
I spend the morning working with Ashley to build a candidate drive sequence for Monday. We don't get many opportunities to let an RP-in-training do something like this when there's no time pressure, so it seems like the perfect time.
When we're all done, we've got a sequence that Ashitey will build on for our first drive next week. And I go off to start clearing away the crushing backlog of other work.
[Next post: sol 664, November 15.]
I spend the morning working with Ashley to build a candidate drive sequence for Monday. We don't get many opportunities to let an RP-in-training do something like this when there's no time pressure, so it seems like the perfect time.
When we're all done, we've got a sequence that Ashitey will build on for our first drive next week. And I go off to start clearing away the crushing backlog of other work.
[Next post: sol 664, November 15.]
2010-11-10
Spirit Sol 660
Today we're planning two sols, 660 and 661. Spirit finds herself poised before an enticing chunk of outcrop called "Larry's Bench," and the question on the science team's mind is whether we want to IDD the part we can reach, or reposition the rover to IDD another part, just to the right.
At first, this seems like a silly question to me. How can this bit of outcrop be so much different from a chunk of the same stuff, a few centimeters away, that it's worth spending even one sol to reach the other bit? (Indeed, it would end up being two sols; VEX needs at least one of our uplinks.)
The answer, it turns out, is dust. The stuff in front of us is pretty dusty, and there's no very good surface to RAT-brush it. But the competing section is already less dusty and has a broader and flatter surface that may be more amenable to brushing.
But maybe we can brush the part in front of us ... and so the discussion goes on, and on, and on. The SOWG meeting, which we normally try to finish in under an hour, goes to an hour and a half. And a good chunk of it is spent going in circles, at that. Alicia Falacarro -- now Alicia Vaughan -- can't stand it when the meetings go this way. She looks at me, rolls her eyes, and groans, "Definitely the J.V. team today."
But the answer in the end is that we're going to IDD, not drive, and the IDD work is reasonably straightforward. (Ed Guinness names the IDD target "Thrasher" -- "since that's what we did in this meeting.") Indeed, Ashitey does most of it. It's your standard unstow, MB touch, MI-2x2x5+stereo, MB re-touch, RAT-brush, post-brush MI-2x2x5+stereo, MB re-touch, APXS kind of sol. Oh, and then another change-tool back to MB on the following sol.
Matt Heverly is shadowing me today, so I take the time to walk him carefully through the whole sequence and talk over his questions in detail. The price of this attention, of course, is that I put him on the hook to do the walkthrough at the CAM. And a good job he does of it, too.
Sol 661. Sol six hundred and sixty-one. Unfathomable. It's almost a Martian year -- a Martian year being 669.7 sols. They're going to celebrate it in von Karman next week.
Six hundred. And sixty-one.
And counting.
[Next post: sol 662, November 13.]
Courtesy NASA/JPL-Caltech. Larry's Bench, right between our wheels.
At first, this seems like a silly question to me. How can this bit of outcrop be so much different from a chunk of the same stuff, a few centimeters away, that it's worth spending even one sol to reach the other bit? (Indeed, it would end up being two sols; VEX needs at least one of our uplinks.)
The answer, it turns out, is dust. The stuff in front of us is pretty dusty, and there's no very good surface to RAT-brush it. But the competing section is already less dusty and has a broader and flatter surface that may be more amenable to brushing.
But maybe we can brush the part in front of us ... and so the discussion goes on, and on, and on. The SOWG meeting, which we normally try to finish in under an hour, goes to an hour and a half. And a good chunk of it is spent going in circles, at that. Alicia Falacarro -- now Alicia Vaughan -- can't stand it when the meetings go this way. She looks at me, rolls her eyes, and groans, "Definitely the J.V. team today."
But the answer in the end is that we're going to IDD, not drive, and the IDD work is reasonably straightforward. (Ed Guinness names the IDD target "Thrasher" -- "since that's what we did in this meeting.") Indeed, Ashitey does most of it. It's your standard unstow, MB touch, MI-2x2x5+stereo, MB re-touch, RAT-brush, post-brush MI-2x2x5+stereo, MB re-touch, APXS kind of sol. Oh, and then another change-tool back to MB on the following sol.
Matt Heverly is shadowing me today, so I take the time to walk him carefully through the whole sequence and talk over his questions in detail. The price of this attention, of course, is that I put him on the hook to do the walkthrough at the CAM. And a good job he does of it, too.
Sol 661. Sol six hundred and sixty-one. Unfathomable. It's almost a Martian year -- a Martian year being 669.7 sols. They're going to celebrate it in von Karman next week.
Six hundred. And sixty-one.
And counting.
[Next post: sol 662, November 13.]
Courtesy NASA/JPL-Caltech. Larry's Bench, right between our wheels.
2010-11-08
Opportunity Sol 637 (Spirit Sol 658)
Thisol I'm RP-1 on Opportunity, and Paolo's soloing as RP-2. But it's a straightforward IDD sol, and he hasn't had many chances to practice IDDing, so he asks if he can carry the bulk of it and I accept.
This is convenient for me, since I'm putting together a training presentation. At Sharon's prodding, I'm doing something Saina asked for, oh, I've lost track of how many months ago: trying to educate the rest of the uplink team about what rover drivers do, what all the mobility commands mean, and so on. This presentation has turned into something of a monster -- about 75 slides -- and I'm not done with it yet. So being able to turn Paolo loose, even part of the time, and work on this presentation, turns out to be an enormous help.
Of course, when he needs me, I watch over Paolo's shoulder and guide him through the process. But he's doing pretty well already.
When we catch a break, he asks me wonderingly, "How did you guys train originally?"
I tell him about the thread tests, the limited training sessions we had, and so on. But it wasn't really much. "If a new candidate rover driver came along who knew only as much as I knew when we landed, I wouldn't let him anywhere near the rovers," I say truthfully. "But we made it through somehow."[1]
How, I'll never know. Mars must have been in a good mood.
[Next post: sol 660, November 10.]
Footnotes:
[1] Sadly, five years on, this has only become even more true: it's gotten harder and harder to drive the rovers, because the list of things you need to know has expanded so much. Also, our training opportunities are more limited right now: Spirit's not driving, and Opportunity ops tends to be very routine, with limited IDD work and drives that all look much the same as we cruise across the plains. So it's become harder and harder to train new people, no matter how sharp and talented they might be (as both of our current trainees are).
This is convenient for me, since I'm putting together a training presentation. At Sharon's prodding, I'm doing something Saina asked for, oh, I've lost track of how many months ago: trying to educate the rest of the uplink team about what rover drivers do, what all the mobility commands mean, and so on. This presentation has turned into something of a monster -- about 75 slides -- and I'm not done with it yet. So being able to turn Paolo loose, even part of the time, and work on this presentation, turns out to be an enormous help.
Of course, when he needs me, I watch over Paolo's shoulder and guide him through the process. But he's doing pretty well already.
When we catch a break, he asks me wonderingly, "How did you guys train originally?"
I tell him about the thread tests, the limited training sessions we had, and so on. But it wasn't really much. "If a new candidate rover driver came along who knew only as much as I knew when we landed, I wouldn't let him anywhere near the rovers," I say truthfully. "But we made it through somehow."[1]
How, I'll never know. Mars must have been in a good mood.
[Next post: sol 660, November 10.]
Footnotes:
[1] Sadly, five years on, this has only become even more true: it's gotten harder and harder to drive the rovers, because the list of things you need to know has expanded so much. Also, our training opportunities are more limited right now: Spirit's not driving, and Opportunity ops tends to be very routine, with limited IDD work and drives that all look much the same as we cruise across the plains. So it's become harder and harder to train new people, no matter how sharp and talented they might be (as both of our current trainees are).
2010-11-05
Spirit Sol 655
The plan is to drive 17m at an azimuth of 130deg. But I have a better idea. We're perched at the top of a local hillock, and spread out below us is Haskin Ridge. We've got a beautiful view of it, a superb terrain mesh -- and, best of all, three hours of driving in the plan.
I think we can do more like 100m.
And it should be fairly simple. The hillock itself is pretty steep -- we might see 22deg tilt on the way down it -- but that's only for the first 15m or so. After that, the terrain quickly shallows out, so that we're in a far more forgiving 8-10deg of tilt all the way down. We can do 50m blind, and the terrain beyond looks decent for autonav. We don't get opportunities like this so often that we can just throw them away.
The day has its ups and downs. It turns out they forgot about a coordinated observation with HST, so they have to completely swap the plan around, but we still end up with about three hours of driving time. And Squyres decides they'd rather we drove at an azimuth of more like 100deg than 130deg, so that they can do a long-baseline stereo observation along the ridge. But at the end of the day, we've got a 110m drive planned, and a real shot at making it to the end -- or at least breaking 100m.
I expect to have real problems selling this to management, but everyone's pretty enthusiastic. When I tell Jim how far we're driving, he says, "I'd kill to get that on Opportunity right now." Then he reconsiders. "Well ... I'd wound," he amends.
Not surprisingly, John Wright -- one of the more aggressive drivers, and RP-2 today -- is fully up for this. "Throw caution to the wind!" he says.
"It's thrown!" I answer.
"Damn the torpedoes!"
"Damned!"
A LATER NOTE:
That was Thursday. We were planning well ahead, for a drive to execute Saturday. And Friday, Chris and Ashitey look at the drive and decide to raise some objections.
Their basic argument is reasonable enough: we're driving into terrain that looks benign enough, but in the hills we've found that we can get bogged down even at relatively low tilts and in terrain that looks benign from a distance. So we should add slip checks to the sequence.
John and I don't really agree, and I don't want to call in the uplink team on a day they'd been promised off, but I can't say they're being unreasonable. And our general approach is that if an RP has a reasonable concern, we take it seriously. So I call in Jake Matijevic and Beth Dewell, and they agree that we should act on Chris's concerns.
The required sequencing is easy enough. I simply break up the final waypoint into 15m segments, adding a slip check between segments. Voila.
John complains bitterly about this: "They're just trying to see to it that we don't get our hundred meters."
"Look," I tell him, "they've got a reasonable concern and we've agreed to act on it, so there's no use arguing about it now."
"I agree," he nods. "But I never said I wouldn't bitch about it."
Good point.
A LATER NOTE [2]:
94 meters. It doesn't quite have the cachet of 100m, but who cares? It feels gooood.
[Next post: sol 658 (Opportunity sol 637), November 8.]
I think we can do more like 100m.
And it should be fairly simple. The hillock itself is pretty steep -- we might see 22deg tilt on the way down it -- but that's only for the first 15m or so. After that, the terrain quickly shallows out, so that we're in a far more forgiving 8-10deg of tilt all the way down. We can do 50m blind, and the terrain beyond looks decent for autonav. We don't get opportunities like this so often that we can just throw them away.
The day has its ups and downs. It turns out they forgot about a coordinated observation with HST, so they have to completely swap the plan around, but we still end up with about three hours of driving time. And Squyres decides they'd rather we drove at an azimuth of more like 100deg than 130deg, so that they can do a long-baseline stereo observation along the ridge. But at the end of the day, we've got a 110m drive planned, and a real shot at making it to the end -- or at least breaking 100m.
I expect to have real problems selling this to management, but everyone's pretty enthusiastic. When I tell Jim how far we're driving, he says, "I'd kill to get that on Opportunity right now." Then he reconsiders. "Well ... I'd wound," he amends.
Not surprisingly, John Wright -- one of the more aggressive drivers, and RP-2 today -- is fully up for this. "Throw caution to the wind!" he says.
"It's thrown!" I answer.
"Damn the torpedoes!"
"Damned!"
A LATER NOTE:
That was Thursday. We were planning well ahead, for a drive to execute Saturday. And Friday, Chris and Ashitey look at the drive and decide to raise some objections.
Their basic argument is reasonable enough: we're driving into terrain that looks benign enough, but in the hills we've found that we can get bogged down even at relatively low tilts and in terrain that looks benign from a distance. So we should add slip checks to the sequence.
John and I don't really agree, and I don't want to call in the uplink team on a day they'd been promised off, but I can't say they're being unreasonable. And our general approach is that if an RP has a reasonable concern, we take it seriously. So I call in Jake Matijevic and Beth Dewell, and they agree that we should act on Chris's concerns.
The required sequencing is easy enough. I simply break up the final waypoint into 15m segments, adding a slip check between segments. Voila.
John complains bitterly about this: "They're just trying to see to it that we don't get our hundred meters."
"Look," I tell him, "they've got a reasonable concern and we've agreed to act on it, so there's no use arguing about it now."
"I agree," he nods. "But I never said I wouldn't bitch about it."
Good point.
A LATER NOTE [2]:
94 meters. It doesn't quite have the cachet of 100m, but who cares? It feels gooood.
[Next post: sol 658 (Opportunity sol 637), November 8.]
2010-10-29
Opportunity Sol 627 (Spirit Sol 648)
This was one of the busiest days I've had lately. RP-1 shifts are usually busier than RP-2 shifts, but this one reminds me of the super-stressful days of the nominal mission. It's not as bad as that, but it's close.
Naturally, I loved every minute of it.
Yestersol's drive was another good one. It went only 35m, including 15m of autonav, mainly because we were limited by the lack of PCAM coverage. But at the end, we turned for comm, so we got a good downlink and are rarin' to go again.
Of course, our comm direction is basically north, and we have to drive basically south. So we have to do a nearly 180-degree turn, on a vehicle where large point turns are prohibited, and in a relatively confined space (due to ripples before and behind).
Our first approach is to drive backward down the current trough a bit past the point where we plan to hop the ripples, then do a series of sharp forward arcs that change direction and put us in the next trough over. (We have to end up heading forward at some point because we can't autonav backward as well when using the NCAMs -- their view of the nearby terrain is blocked by the rover deck.)
But this involves a bit too much uncertainty, so I bag it for a different approach. Counterclockwise arcs work well even with the stuck RF steering actuator and aren't subject to any rules-of-the-road limits, so I decide to use a bunch of those. First, we arc 75cm forward with a 22.5-degree counterclockwise heading change. Then we back straight up 50cm. We repeat this maneuver until we have the desired heading, then drive on -- straight -- for the rest of the sol.
Why not make the forward and backward arcs the same length? Because that would take us back and forth over the soil in the same spot too many times, and we're a bit worried about whether that will interfere with our traversability here. We had an experience like that in Endurance, and it left its mark. Of course, maybe it will just compact the soil and make driving better, not worse -- but if we always knew stuff like that, it wouldn't be exploration. So we try the asymmetric approach, and document it copiously with HAZCAMs as we go. And somesol soon, when those images get downlinked, we'll know whether this is a good or bad technique to use next time.
Other than that, this drive is not too remarkable -- about 30m blind, then switch to autonav. All through the sol, our TUL, Rich Morris works to free up more time, and when he's done, we have a whopping two hours and 47 minutes. This is a little embarrassing for me, actually, since if the slip checks work a little faster than they have been, we might actually complete the drive. That wouldn't be such a bad thing, although it would be a shame to waste any time.
Emily Eelkema's picture of the day is an image emailed to her by Ray Arvidson, a picture of the Rio Tinto. This is a naturally highly acidic river in Spain, so acidic that it's actually red. Some shallow pools of the stuff, the color of a nice Cabernet, take on a jelly-like consistency if you stir them. "That's Meridiani Planum, four billion years ago," says Ray. How appropriate. Even Mars's water was red.
And the Red Planet -- and with it, of course, our girls Spirit and Opportunity -- are about as close as they're going to get for a while. The one-way light-time is three minutes 52 seconds. Monday it will start rising again. Mars makes its closest approach at 8:52 PM Saturday -- tomorrow. Maybe I'll take Zenobia[1] outside with me and have a look at it.
[Next post: sol 655, November 5.]
[1] My cat, then. She was ornery and bossy and I loved her to pieces.
Naturally, I loved every minute of it.
Yestersol's drive was another good one. It went only 35m, including 15m of autonav, mainly because we were limited by the lack of PCAM coverage. But at the end, we turned for comm, so we got a good downlink and are rarin' to go again.
Of course, our comm direction is basically north, and we have to drive basically south. So we have to do a nearly 180-degree turn, on a vehicle where large point turns are prohibited, and in a relatively confined space (due to ripples before and behind).
Our first approach is to drive backward down the current trough a bit past the point where we plan to hop the ripples, then do a series of sharp forward arcs that change direction and put us in the next trough over. (We have to end up heading forward at some point because we can't autonav backward as well when using the NCAMs -- their view of the nearby terrain is blocked by the rover deck.)
But this involves a bit too much uncertainty, so I bag it for a different approach. Counterclockwise arcs work well even with the stuck RF steering actuator and aren't subject to any rules-of-the-road limits, so I decide to use a bunch of those. First, we arc 75cm forward with a 22.5-degree counterclockwise heading change. Then we back straight up 50cm. We repeat this maneuver until we have the desired heading, then drive on -- straight -- for the rest of the sol.
Why not make the forward and backward arcs the same length? Because that would take us back and forth over the soil in the same spot too many times, and we're a bit worried about whether that will interfere with our traversability here. We had an experience like that in Endurance, and it left its mark. Of course, maybe it will just compact the soil and make driving better, not worse -- but if we always knew stuff like that, it wouldn't be exploration. So we try the asymmetric approach, and document it copiously with HAZCAMs as we go. And somesol soon, when those images get downlinked, we'll know whether this is a good or bad technique to use next time.
Other than that, this drive is not too remarkable -- about 30m blind, then switch to autonav. All through the sol, our TUL, Rich Morris works to free up more time, and when he's done, we have a whopping two hours and 47 minutes. This is a little embarrassing for me, actually, since if the slip checks work a little faster than they have been, we might actually complete the drive. That wouldn't be such a bad thing, although it would be a shame to waste any time.
Emily Eelkema's picture of the day is an image emailed to her by Ray Arvidson, a picture of the Rio Tinto. This is a naturally highly acidic river in Spain, so acidic that it's actually red. Some shallow pools of the stuff, the color of a nice Cabernet, take on a jelly-like consistency if you stir them. "That's Meridiani Planum, four billion years ago," says Ray. How appropriate. Even Mars's water was red.
And the Red Planet -- and with it, of course, our girls Spirit and Opportunity -- are about as close as they're going to get for a while. The one-way light-time is three minutes 52 seconds. Monday it will start rising again. Mars makes its closest approach at 8:52 PM Saturday -- tomorrow. Maybe I'll take Zenobia[1] outside with me and have a look at it.
[Next post: sol 655, November 5.]
[1] My cat, then. She was ornery and bossy and I loved her to pieces.
2010-10-28
Opportunity Sol 626 (Spirit Sol 647)
Our autonav drive actually went great -- a total of 45 meters, quite respectable by current standards. That means we got about 15m out of the autonav, which is good news.
The only fly in the ointment is that we failed to do our turn for comm, and for a reason we should have thought of. When we planned this drive, we planned for it to extend beyond the time-of-day limit. This is common -- indeed, something we used to do all the time when using autonav; we just have it drive until the time-of-day limit kicks in, then we have the sequence detect that we were stopped by the time-of-day limit, clear the error, and reset the limit to allow time for end-of-drive activities such as turning to comm. We did all that logic on this drive, so we thought we were in the clear.
But here's what we forgot: both the blind and autonav portions of the drive are punctuated by slip checks, helper subsequences that try to drive a short distance and preclude further driving if we didn't make a decent fraction of the commanded distance. After the time-of-day limit hit, the sequence dutifully tried a slip check, noticed that it hadn't actually gone anywhere, and precluded driving. This is something our end-of-sol error-clearing logic didn't check for (indeed, has no good way to check for). So we still had an error -- the rover thought it was stuck in another dune -- and we didn't turn for comm.
Oops. We're still happy, but oops.
Well, our downlink was still pretty good. We didn't get the PCAMs, so that limits our blind driving thisol.
Hey, no problem. Jeng and I plan a sequence that drives blind as far as possible, then uses autonav until stopped by the time-of-day limit.
And this time, we do it correctly.
The only fly in the ointment is that we failed to do our turn for comm, and for a reason we should have thought of. When we planned this drive, we planned for it to extend beyond the time-of-day limit. This is common -- indeed, something we used to do all the time when using autonav; we just have it drive until the time-of-day limit kicks in, then we have the sequence detect that we were stopped by the time-of-day limit, clear the error, and reset the limit to allow time for end-of-drive activities such as turning to comm. We did all that logic on this drive, so we thought we were in the clear.
But here's what we forgot: both the blind and autonav portions of the drive are punctuated by slip checks, helper subsequences that try to drive a short distance and preclude further driving if we didn't make a decent fraction of the commanded distance. After the time-of-day limit hit, the sequence dutifully tried a slip check, noticed that it hadn't actually gone anywhere, and precluded driving. This is something our end-of-sol error-clearing logic didn't check for (indeed, has no good way to check for). So we still had an error -- the rover thought it was stuck in another dune -- and we didn't turn for comm.
Oops. We're still happy, but oops.
Well, our downlink was still pretty good. We didn't get the PCAMs, so that limits our blind driving thisol.
Hey, no problem. Jeng and I plan a sequence that drives blind as far as possible, then uses autonav until stopped by the time-of-day limit.
And this time, we do it correctly.
2010-10-27
Opportunity Sol 625 (Spirit Sol 646)
I've switched rovers once more. Back in the Land of Opportunity, they've backed away from the northern part of Erebus Crater -- pretty far away, as in 100m or so -- and now we're planning a drive to the west side of Erebus Crater. They had to back off so far because of the enormous ripples they encountered in the crater's immediate vicinity, and we're going to keep our distance as we head west.
Or that's what Frank and I think. The scientists would like to complicate things by adding a stop to the tour: in the orbital images, we can see a large expanse of outcrop at the northwest part of the crater. Can we stop by on the way?
Frank puts it to them bluntly: we can drive south to that outcrop, but if the ripples there are like they are elsewhere near the crater, we won't be able to go directly from there to the point where they're thinking of entering Erebus. Instead, we'll have to drive north from the outcrop before we can drive west to the point where we can drive south to get to the west entrance. Just thinking about it is enough to make your head spin, and it'll definitely make our wheels spin for an extra week or more.
This leads to the usual lengthy back-and-forth, and eventually to a compromise solution: we'll drive a little south of west, at an azimuth of 240 or so, hoping it will help us reconnoiter without driving all the way to the outcrop. If what we see tells us that the outcrop would be an expensive journey, we'll skip it; else we'll go there.
No matter how we do it, this will be a lot of driving. So I suggest to Frank that Opportunity revive an old trick, one Spirit uses often but Opportunity hasn't used for quite a while: autonav. We're in such a benign zone right now -- no ripples over 15cm, and nearly all under 10cm or so -- that we ought to take advantage of it to get as much extra distance per sol as we can.
Frank readily agrees. In fact, as it turns out, he and Jeng tried to do just this a few weeks ago, but that drive stopped for other reasons before it got to the autonav section. Nevertheless, it's a straightforward matter to add an autonav section to thisol's drive sequence.
When we actually do the math ... even with about two and a half hours to drive, the visodom-based slip checks are just so time-consuming that autonav is going to end up giving us only 5 or 10 meters. That's discouraging, but, well, it's something. Five meters here, 10 meters there, pretty soon you're talking about ... well ... it's something.
Or that's what Frank and I think. The scientists would like to complicate things by adding a stop to the tour: in the orbital images, we can see a large expanse of outcrop at the northwest part of the crater. Can we stop by on the way?
Frank puts it to them bluntly: we can drive south to that outcrop, but if the ripples there are like they are elsewhere near the crater, we won't be able to go directly from there to the point where they're thinking of entering Erebus. Instead, we'll have to drive north from the outcrop before we can drive west to the point where we can drive south to get to the west entrance. Just thinking about it is enough to make your head spin, and it'll definitely make our wheels spin for an extra week or more.
This leads to the usual lengthy back-and-forth, and eventually to a compromise solution: we'll drive a little south of west, at an azimuth of 240 or so, hoping it will help us reconnoiter without driving all the way to the outcrop. If what we see tells us that the outcrop would be an expensive journey, we'll skip it; else we'll go there.
No matter how we do it, this will be a lot of driving. So I suggest to Frank that Opportunity revive an old trick, one Spirit uses often but Opportunity hasn't used for quite a while: autonav. We're in such a benign zone right now -- no ripples over 15cm, and nearly all under 10cm or so -- that we ought to take advantage of it to get as much extra distance per sol as we can.
Frank readily agrees. In fact, as it turns out, he and Jeng tried to do just this a few weeks ago, but that drive stopped for other reasons before it got to the autonav section. Nevertheless, it's a straightforward matter to add an autonav section to thisol's drive sequence.
When we actually do the math ... even with about two and a half hours to drive, the visodom-based slip checks are just so time-consuming that autonav is going to end up giving us only 5 or 10 meters. That's discouraging, but, well, it's something. Five meters here, 10 meters there, pretty soon you're talking about ... well ... it's something.
2010-10-26
Spirit Sol 645
I'm Spirit's RP-1 today, but Spirit doesn't really need an RP. That's because they planned two sols yesterday, leaving nothing for an RP to do today.
Well, not quite nothing: I do have to weigh in on whether we should take PCAMs to support a possible southward, as opposed to the originally planned eastward, drive. My reaction: meh. We still ought to drive (eastward) to the lip and see if the slope there is as bad as we suspect before we give up on that path and head southward, so a south-looking PCAM from this position isn't likely to help much. But they're looking to spend the bits and taking it does keep our options open, so they take it anyway.
See? I'm not completely useless today.
Well, not quite nothing: I do have to weigh in on whether we should take PCAMs to support a possible southward, as opposed to the originally planned eastward, drive. My reaction: meh. We still ought to drive (eastward) to the lip and see if the slope there is as bad as we suspect before we give up on that path and head southward, so a south-looking PCAM from this position isn't likely to help much. But they're looking to spend the bits and taking it does keep our options open, so they take it anyway.
See? I'm not completely useless today.
2010-10-23
Spirit Sol 642
Spirit saw no safe path, so she gave up after only about 14m. Happily, this is mainly due to the conservative autonav settings; the new images reveal a perfectly safe path straight to the lip, now about 20m away.
But between us and the lip is an enormous patch of outcrop, and it might just be too shiny for the science team to ignore. They're going into restricted sols next week, so if we stop to IDD this outcrop, we're going to end up spending the whole week at it. That's a big time investment, considering that the sun's gradual southward motion means we now have a deadline to get to south-facing slopes.
"RPs, whaddaya think?" Steve asks.
"It's a science mission," I answer. "You know the constraints as well as anyone. If this is important for science, then let's delay going to the lip."
And that's what we do. So the drive itself turns out to be pretty easy, just a gentle 6.7m descent to a big outcrop patch. I have a bad feeling about it, just the same. Something about it reminds me of the hell that was Mazatzal: a big time investment in a highly important science target, a low rock just 7m away, and I think it's easy ... and I came in after that drive to find out we didn't really hit our target, and I felt miserable for a week. (And I still feel that way about it, in case you can't tell.) So I check and recheck, and if I made a mistake thisol, it won't be because I didn't try to learn the lesson.
The rock itself is named "Kansas." This is continuing the practice of naming stuff in this area in honor of Larry Haskin, who apparently was a well-liked friend and well-respected colleague to many on the science team (and who is, sadly, now deceased). Apparently, he had a farm in Kansas, and targets on the rock will be named after towns near his farm.
Me, I'm just excited because when we drive away, we'll get to say that we don't think we're in Kansas any more.
[Next post: sol 645, October 26.]
But between us and the lip is an enormous patch of outcrop, and it might just be too shiny for the science team to ignore. They're going into restricted sols next week, so if we stop to IDD this outcrop, we're going to end up spending the whole week at it. That's a big time investment, considering that the sun's gradual southward motion means we now have a deadline to get to south-facing slopes.
"RPs, whaddaya think?" Steve asks.
"It's a science mission," I answer. "You know the constraints as well as anyone. If this is important for science, then let's delay going to the lip."
And that's what we do. So the drive itself turns out to be pretty easy, just a gentle 6.7m descent to a big outcrop patch. I have a bad feeling about it, just the same. Something about it reminds me of the hell that was Mazatzal: a big time investment in a highly important science target, a low rock just 7m away, and I think it's easy ... and I came in after that drive to find out we didn't really hit our target, and I felt miserable for a week. (And I still feel that way about it, in case you can't tell.) So I check and recheck, and if I made a mistake thisol, it won't be because I didn't try to learn the lesson.
The rock itself is named "Kansas." This is continuing the practice of naming stuff in this area in honor of Larry Haskin, who apparently was a well-liked friend and well-respected colleague to many on the science team (and who is, sadly, now deceased). Apparently, he had a farm in Kansas, and targets on the rock will be named after towns near his farm.
Me, I'm just excited because when we drive away, we'll get to say that we don't think we're in Kansas any more.
[Next post: sol 645, October 26.]
2010-10-20
Spirit Sol 639
Ahh, it's one of those sols where we don't have to start until noon. Oh, my, this feels wonderful.
"I got to sleep until ten today," I say blissfully to Saina.
"I can't sleep until ten," she says. "I get bored."
Which makes no sense to me. But there's not much time to dwell on it; we've got a rover to drive.
About 25-30m away from us, the terrain slopes down more sharply. We can't see over this lip, so we don't know if there's a safe path to Haskin Ridge from here. So our plan is, naturally, to drive to the lip and peek over. If we like what we see, we keep going; if not, we'll have to head most of the way back up to the summit and find a different path down.
Between us and the lip, there's another problem. About 15m from here, there's a series of obstacles that cuts across our path. To the left is a ridge; to the right is a knoll -- which is, perversely, both too tall and too narrow for us to climb.
And straight ahead is a rock. The rock isn't that tall, only about 10cm on the face we can see. But because of the shape of the terrain around it, we can't tell what the terrain looks like on the far side, meaning we can't tell what slopes or dropoffs the rover will experience as it climbs over. The first point we can see beyond the rock is 30cm below the rock's top, meaning the rover could potentially experience a dropoff of that size, and that's too big for this vehicle.
The solution: let the rover handle it. Our plan is to drive Spirit about 11m straight toward the danger area, then turn on autonav and let her find her own path through. (Starting autonav a few meters back from the hazardous area means she can see more of it, giving her a better chance to find a passage.) If she finds a way, great. If she doesn't, then at least tomorrow will bring us better images, which we can maybe use to blind-drive past this troublesome area.
[Next post: sol 642, October 23.]
"I got to sleep until ten today," I say blissfully to Saina.
"I can't sleep until ten," she says. "I get bored."
Which makes no sense to me. But there's not much time to dwell on it; we've got a rover to drive.
About 25-30m away from us, the terrain slopes down more sharply. We can't see over this lip, so we don't know if there's a safe path to Haskin Ridge from here. So our plan is, naturally, to drive to the lip and peek over. If we like what we see, we keep going; if not, we'll have to head most of the way back up to the summit and find a different path down.
Between us and the lip, there's another problem. About 15m from here, there's a series of obstacles that cuts across our path. To the left is a ridge; to the right is a knoll -- which is, perversely, both too tall and too narrow for us to climb.
And straight ahead is a rock. The rock isn't that tall, only about 10cm on the face we can see. But because of the shape of the terrain around it, we can't tell what the terrain looks like on the far side, meaning we can't tell what slopes or dropoffs the rover will experience as it climbs over. The first point we can see beyond the rock is 30cm below the rock's top, meaning the rover could potentially experience a dropoff of that size, and that's too big for this vehicle.
The solution: let the rover handle it. Our plan is to drive Spirit about 11m straight toward the danger area, then turn on autonav and let her find her own path through. (Starting autonav a few meters back from the hazardous area means she can see more of it, giving her a better chance to find a passage.) If she finds a way, great. If she doesn't, then at least tomorrow will bring us better images, which we can maybe use to blind-drive past this troublesome area.
[Next post: sol 642, October 23.]
2010-10-18
Opportunity Sol 616 (Spirit Sol 637)
It's 06:30 at the start of a tight sol, and Beth Dewell is as bleary-eyed as I am.
"I think the rovers were missing you guys," she yawns, reciting the litany of things that went wrong while most of us rover drivers were away at the conference. Opportunity underwent another mystery reset during the AM science block, then missed a crucial part of the uplink, so that she ended up doing nothing but runout science for a couple of days. And we had ground system problems, with a crashing file server among other things. ("I think you can say that Friday was legally a nightmare," as Brenda Franklin puts it.) There's more, but I'm too tired to remember it.
It's not a terribly difficult day, just a Sunday -- er, Monday -- drive, hunting decent ripple-crossing spots as we trend west around Erebus Crater. The only hard bit is that we're on such a tight schedule: we need to be done by about 13:00.
And, what the hell, we make it. Man, I need a nap.
[Next post: sol 639, October 20.]
"I think the rovers were missing you guys," she yawns, reciting the litany of things that went wrong while most of us rover drivers were away at the conference. Opportunity underwent another mystery reset during the AM science block, then missed a crucial part of the uplink, so that she ended up doing nothing but runout science for a couple of days. And we had ground system problems, with a crashing file server among other things. ("I think you can say that Friday was legally a nightmare," as Brenda Franklin puts it.) There's more, but I'm too tired to remember it.
It's not a terribly difficult day, just a Sunday -- er, Monday -- drive, hunting decent ripple-crossing spots as we trend west around Erebus Crater. The only hard bit is that we're on such a tight schedule: we need to be done by about 13:00.
And, what the hell, we make it. Man, I need a nap.
[Next post: sol 639, October 20.]
2010-10-08
Spirit Sol 627
"We can't say we're stable," Ashitey says, "and we can't say we're unstable." What we know is, we wiggled the wheels, and we slipped. But we slipped more the first and second time, losing about two degrees of overall tilt in the process; the change on the third wiggle was definitely less. But then, at the end, when we cocked the wheels against the direction of slip, we slipped more during that motion.
My take on this is that everything is in fact just fine. We're on a slope; we're tilted; we're going to move when we wiggle the wheels. But we shouldn't be freaking out about that, because it's not what we care about. What we care about is whether we're going to move (or tilt) when we deploy the IDD, which is a different question. And when you look at how little we slip when we wiggle the wheels, I think you'd have a hard time saying we're going to slip when we deploy the IDD.
We're freaking out more because we took the wiggle-cam images -- hazcams before and after wiggling the wheels -- when we first got here, and we saw a change in those images. But the thing is, we've never taken such images before, so we don't really know whether that change is in family with what's happened previously.
At the SOWG meeting, I advocate a staged approach. Take it slowly. On the first sol, just deploy the IDD -- nothing more. Take images before and after this deployment. If we see any vehicle motion, or an unacceptable change in tilt, don't uplink the next IDD sequence. On the second sol, we do just one more thing -- place the MB. Again, accompany this with lots of imaging, and pull the plug on the process if we see any unexpected changes. We'll go on in this way for each of the days until the RPs are back in town (nearly everyone's going out of town for a convention).
This is generally accepted, in principle, although Emily is still reluctant to deploy at all. ("I reserve the right to change my mind," she is careful to say.)
So Ashitey and I move ahead on working out these sequences. They're not hard, but it turns out that this is one of those days with a high debate-to-command ratio. We're only about halfway done when Justin Maki puts together a movie showing each image of the rover sliding as we had it wiggle its wheels several times over the last few days, and then the concerns blow up again.
That isn't the only thing that blows up. Ashitey and Justin get into an argument about whether it's safe to deploy, and Ashitey just loses his cool. Ashitey's trying to make the point that our decision should be based on analysis, not on anyone's gut feeling, but Justin keeps cutting him off. Suddenly, Ashitey's had enough. "Stop interrupting!" he snaps. Next thing I know, Justin's grabbed his coffee and stalked out the door.
This is not a normal sol.
By this time I've already realized two things. One is that I need to stop advocating a position and go back to basics: regardless of any questions about winning or losing, what is objectively the best thing to do?[1] And second, we need to know whether what we're seeing is normal behavior in similar conditions.
We haven't taken wiggle-cams before, which is part of the problem. But we do have very good data on the tilt changes. We always collect this data at 8Hz -- the maximum rate the rover's capable of -- during wheel wiggles. So I've been trolling through past sols, looking for times when our tilt's been high. I find a couple of these, plot the tilt data, and -- yep, looks to me like what we saw is normal. I still have to convince the doubters, but it's good evidence.
But first I have another concern. Justin's a smart guy who's done a lot of good on this mission, and we ought to make sure we've heard him out on this topic. So I track him down -- he's upstairs, in the Opportunity room -- and talk it out with him. In the end, it's just gut feeling on his part (he says so himself), and while I don't want to dismiss gut feelings, evidence counts for more. (While we're having this conversation, Ashitey comes to find me. And apologizes to Justin. So that's back on track.)
Also in the Opportunity sequencing room is Jeff Biesiadecki. He knows the rover's mobility system better than almost anybody, and we don't call him "Paranoid Jeff" for nothing, so we drag him downstairs to have a look through it. Somewhat to our surprise, not that we're complaining, Paranoid Jeff gives our careful, phased plan a thumbs-up. So far, so good.
But Khaled gets wind of this, and objects. Strongly. "I wouldn't deploy in this situation," he says firmly, "no way." He doesn't directly take issue with the historical data showing that what we're seeing seems to be normal, but he raises the Shuttle Fallacy: just because we've gotten away with something dangerous in the past, that doesn't mean we're safe to do it again in the future.
"The problem with that," I point out, "is that in situations like this you don't know whether what you're doing is dangerous, and you're getting away with it; or it's safe, and you're worrying for nothing. You can't tell the difference between the two cases without data, and the data we have shows that the rover doesn't tilt excessively when we deploy the IDD in circumstances as close to this as we've gotten."
The debate rages. Some people are trying to figure out exactly where the left front wheel is, and in particular whether it's solidly planted. Jim Erickson and John Callas get involved. They're arguing with Steve Squyres, who pushes the scientific importance of this particular observation. (Squyres nearly scores an own-goal: when discussing what damage could occur to the IDD in the pose where the MB is deployed, he says, "You know, the steel noseplate on the MB is one of the most robust parts of the arm." You don't say it'll survive the scraping to people who want to hear that it's not going to scrape against anything at all.)
This goes on for, I'm not kidding you, three hours. Emily is stressed. She doesn't want to (seem to) be the one to destroy the IDD, with its irreplaceable science value, but I think that in the end she recognizes she doesn't have a fact-based argument. So she makes the right decision: "We're going to proceed with the deployment," she says at last.
But with careful, objective limits on the tilt changes we'll use to decide whether to pull the plug. (We already have decided that no change in position would be acceptable: even a shift of a millimeter would put a stop to this little excursion. But tilt's another matter: we always see a small change in tilt when we deploy the IDD.) Ashitey and Terry Huntsberger do some additional data mining, to come up with numeric bounds. The final number: 0.3 degrees.
We see more tilt than that, and we switch to an IDD-less, image-heavy backup plan. Less tilt, and we proceed.
Surprisingly, even Khaled eventually agrees to this. And with Paranoid Jeff and Even-More-Paranoid Khaled on board, we must be doing something right.
[Next post: sol 637 (Opportunity sol 616), October 18.]
Courtesy NASA/JPL-Caltech. Slipping slowly down the face of Hillary.
Footnotes:
[1] Always, always, always the right approach. Whenever I've strayed from it, I've regretted it, and whenever I've gone back to that path, I've been glad of it. Always.
My take on this is that everything is in fact just fine. We're on a slope; we're tilted; we're going to move when we wiggle the wheels. But we shouldn't be freaking out about that, because it's not what we care about. What we care about is whether we're going to move (or tilt) when we deploy the IDD, which is a different question. And when you look at how little we slip when we wiggle the wheels, I think you'd have a hard time saying we're going to slip when we deploy the IDD.
We're freaking out more because we took the wiggle-cam images -- hazcams before and after wiggling the wheels -- when we first got here, and we saw a change in those images. But the thing is, we've never taken such images before, so we don't really know whether that change is in family with what's happened previously.
At the SOWG meeting, I advocate a staged approach. Take it slowly. On the first sol, just deploy the IDD -- nothing more. Take images before and after this deployment. If we see any vehicle motion, or an unacceptable change in tilt, don't uplink the next IDD sequence. On the second sol, we do just one more thing -- place the MB. Again, accompany this with lots of imaging, and pull the plug on the process if we see any unexpected changes. We'll go on in this way for each of the days until the RPs are back in town (nearly everyone's going out of town for a convention).
This is generally accepted, in principle, although Emily is still reluctant to deploy at all. ("I reserve the right to change my mind," she is careful to say.)
So Ashitey and I move ahead on working out these sequences. They're not hard, but it turns out that this is one of those days with a high debate-to-command ratio. We're only about halfway done when Justin Maki puts together a movie showing each image of the rover sliding as we had it wiggle its wheels several times over the last few days, and then the concerns blow up again.
That isn't the only thing that blows up. Ashitey and Justin get into an argument about whether it's safe to deploy, and Ashitey just loses his cool. Ashitey's trying to make the point that our decision should be based on analysis, not on anyone's gut feeling, but Justin keeps cutting him off. Suddenly, Ashitey's had enough. "Stop interrupting!" he snaps. Next thing I know, Justin's grabbed his coffee and stalked out the door.
This is not a normal sol.
By this time I've already realized two things. One is that I need to stop advocating a position and go back to basics: regardless of any questions about winning or losing, what is objectively the best thing to do?[1] And second, we need to know whether what we're seeing is normal behavior in similar conditions.
We haven't taken wiggle-cams before, which is part of the problem. But we do have very good data on the tilt changes. We always collect this data at 8Hz -- the maximum rate the rover's capable of -- during wheel wiggles. So I've been trolling through past sols, looking for times when our tilt's been high. I find a couple of these, plot the tilt data, and -- yep, looks to me like what we saw is normal. I still have to convince the doubters, but it's good evidence.
But first I have another concern. Justin's a smart guy who's done a lot of good on this mission, and we ought to make sure we've heard him out on this topic. So I track him down -- he's upstairs, in the Opportunity room -- and talk it out with him. In the end, it's just gut feeling on his part (he says so himself), and while I don't want to dismiss gut feelings, evidence counts for more. (While we're having this conversation, Ashitey comes to find me. And apologizes to Justin. So that's back on track.)
Also in the Opportunity sequencing room is Jeff Biesiadecki. He knows the rover's mobility system better than almost anybody, and we don't call him "Paranoid Jeff" for nothing, so we drag him downstairs to have a look through it. Somewhat to our surprise, not that we're complaining, Paranoid Jeff gives our careful, phased plan a thumbs-up. So far, so good.
But Khaled gets wind of this, and objects. Strongly. "I wouldn't deploy in this situation," he says firmly, "no way." He doesn't directly take issue with the historical data showing that what we're seeing seems to be normal, but he raises the Shuttle Fallacy: just because we've gotten away with something dangerous in the past, that doesn't mean we're safe to do it again in the future.
"The problem with that," I point out, "is that in situations like this you don't know whether what you're doing is dangerous, and you're getting away with it; or it's safe, and you're worrying for nothing. You can't tell the difference between the two cases without data, and the data we have shows that the rover doesn't tilt excessively when we deploy the IDD in circumstances as close to this as we've gotten."
The debate rages. Some people are trying to figure out exactly where the left front wheel is, and in particular whether it's solidly planted. Jim Erickson and John Callas get involved. They're arguing with Steve Squyres, who pushes the scientific importance of this particular observation. (Squyres nearly scores an own-goal: when discussing what damage could occur to the IDD in the pose where the MB is deployed, he says, "You know, the steel noseplate on the MB is one of the most robust parts of the arm." You don't say it'll survive the scraping to people who want to hear that it's not going to scrape against anything at all.)
This goes on for, I'm not kidding you, three hours. Emily is stressed. She doesn't want to (seem to) be the one to destroy the IDD, with its irreplaceable science value, but I think that in the end she recognizes she doesn't have a fact-based argument. So she makes the right decision: "We're going to proceed with the deployment," she says at last.
But with careful, objective limits on the tilt changes we'll use to decide whether to pull the plug. (We already have decided that no change in position would be acceptable: even a shift of a millimeter would put a stop to this little excursion. But tilt's another matter: we always see a small change in tilt when we deploy the IDD.) Ashitey and Terry Huntsberger do some additional data mining, to come up with numeric bounds. The final number: 0.3 degrees.
We see more tilt than that, and we switch to an IDD-less, image-heavy backup plan. Less tilt, and we proceed.
Surprisingly, even Khaled eventually agrees to this. And with Paranoid Jeff and Even-More-Paranoid Khaled on board, we must be doing something right.
[Next post: sol 637 (Opportunity sol 616), October 18.]
Courtesy NASA/JPL-Caltech. Slipping slowly down the face of Hillary.
Footnotes:
[1] Always, always, always the right approach. Whenever I've strayed from it, I've regretted it, and whenever I've gone back to that path, I've been glad of it. Always.
2010-10-07
Spirit Sol 626
This morning brings good news and bad news. The good news is, we made it. This is truly spectacular and receives its due of praise from all concerned: it was one of the most difficult approaches we've ever done, and we nailed it.
The bad news is, it's not safe to IDD. At the end of the drive, we carefully wiggled the wheels, and the data and images show that the vehicle moved during the wiggle. This implies that it might well be unsafe to deploy the IDD. So we won't be able to start IDDing thisol; we're going to have to spend the sol figuring out how to either settle the rover a bit better or bumping to a new position. (We also displaced a rock we drove over on the way in, tilting it up such that there was probably only 2-3cm clearance between it and the bottom of the WEB. Oops.)
The basic decision is: wiggle only, or drive and then wiggle? Ashitey wants to drive first, but I eventually talk him out of it. In this area, treacherous as it is, driving is merely a way of trading the devil we know for the devil we don't. We don't have any good way to raise the odds that we'll be stable at the end of the next little bump, so we might as well try to make Spirit more stable right here.
This argument would probably have been a loser, given that thisol is absolutely our last margin sol -- we can't just try for stability thisol, then drive and try again nextersol if this doesn't work, because we're going to be on travel then. (Or, to put it another way, we could drive nextersol, but there's not much point because nobody will be around to develop the IDD sequences that are the real point of this endeavor.)
But Squyres declares that Hillary is such a high-priority science target that they're willing to wait. If we simply can't get the IDD into position before leaving town, they'll wait until RPs start returning to town Wednesday. That means we have sols to spare, so we can try one thing thisol and something else nextersol if it doesn't work. That's the least risky approach, so we go with that.
The settling tactic itself is a fairly straightforward one. We wiggle each wheel, one at a time, taking plenty of documentation images and visodom updates as we do. Then we cock each wheel to the left, so that the paddles are transverse to the direction of slip. If all goes well, we'll come in tomorrow and see a tiny amount of slip on the first wiggle and no slip after that, and we'll be stable and ready to deploy the IDD. If not, well ... the scientists will have a lander for a few days.
"Alternatively," Steve says, "if this doesn't work, we could give up and drive to another rock. There are other rocks around here -- much less interesting from a science perspective, but they'd probably tell us what we need to know. It's the RPs' call."
"I'm not going to want to give up, Steve," I tell him. "I'm still pissed off about Burns Cliff."
And I am, too.
Courtesy NASA/JPL-Caltech. Some days I rock. Other days I rock hard. This was one of the second kind.
The bad news is, it's not safe to IDD. At the end of the drive, we carefully wiggled the wheels, and the data and images show that the vehicle moved during the wiggle. This implies that it might well be unsafe to deploy the IDD. So we won't be able to start IDDing thisol; we're going to have to spend the sol figuring out how to either settle the rover a bit better or bumping to a new position. (We also displaced a rock we drove over on the way in, tilting it up such that there was probably only 2-3cm clearance between it and the bottom of the WEB. Oops.)
The basic decision is: wiggle only, or drive and then wiggle? Ashitey wants to drive first, but I eventually talk him out of it. In this area, treacherous as it is, driving is merely a way of trading the devil we know for the devil we don't. We don't have any good way to raise the odds that we'll be stable at the end of the next little bump, so we might as well try to make Spirit more stable right here.
This argument would probably have been a loser, given that thisol is absolutely our last margin sol -- we can't just try for stability thisol, then drive and try again nextersol if this doesn't work, because we're going to be on travel then. (Or, to put it another way, we could drive nextersol, but there's not much point because nobody will be around to develop the IDD sequences that are the real point of this endeavor.)
But Squyres declares that Hillary is such a high-priority science target that they're willing to wait. If we simply can't get the IDD into position before leaving town, they'll wait until RPs start returning to town Wednesday. That means we have sols to spare, so we can try one thing thisol and something else nextersol if it doesn't work. That's the least risky approach, so we go with that.
The settling tactic itself is a fairly straightforward one. We wiggle each wheel, one at a time, taking plenty of documentation images and visodom updates as we do. Then we cock each wheel to the left, so that the paddles are transverse to the direction of slip. If all goes well, we'll come in tomorrow and see a tiny amount of slip on the first wiggle and no slip after that, and we'll be stable and ready to deploy the IDD. If not, well ... the scientists will have a lander for a few days.
"Alternatively," Steve says, "if this doesn't work, we could give up and drive to another rock. There are other rocks around here -- much less interesting from a science perspective, but they'd probably tell us what we need to know. It's the RPs' call."
"I'm not going to want to give up, Steve," I tell him. "I'm still pissed off about Burns Cliff."
And I am, too.
Courtesy NASA/JPL-Caltech. Some days I rock. Other days I rock hard. This was one of the second kind.
2010-10-06
Spirit Sol 625
I must be bad luck or something. This is the third consecutive sol I've worked where we were missing important drive imagery.
Thisol we're missing most of the NCAMs that were to support our final approach to Hillary, a juicy rock target here at the true summit of Husband Hill. Fortunately, the one NCAM we do have covers the straightforward approach to Hillary. Unfortunately, the straightforward approach is a no-go for comm reasons. So instead of tackling it head-on in a northward drive, we have to skirt around so that we're heading at it more northeasterly. And this means taking on much higher tilt -- nearly 30 degrees, above our comfort level.
(Hillary is, of course, named in honor of Everest conqueror Sir Edmund Hillary. To my surprise, the man is still alive, in his late eighties. Squyres is planning to email him some images of the rock we've named for him. I find this somehow bizarre, as if we were going to send a fax to Erik the Red.)
We're trying to get Spirit into position to IDD, including some very long-term MB and APXS integrations, for the few days that there's no RP coverage because everyone's in Hawaii. We could possibly recover if we need to use tomorrow (Thursday) for a final bump, but that will make Friday hellacious. And if we don't make it on Thursday either, well, somebody's not going to Hawaii, I guess.
The high tilt on this drive is making everyone nervous. After much discussion, Ashitey and I come up with a set of safeguards that should keep Spirit safe while still giving us a good chance of making it to the goal. An even lengthier discussion sells it to the rest of the uplink team. "Just give me time to update my résumé," deadpans Saina.
Courtesy NASA/JPL-Caltech. Our NCAM of Hillary.
Thisol we're missing most of the NCAMs that were to support our final approach to Hillary, a juicy rock target here at the true summit of Husband Hill. Fortunately, the one NCAM we do have covers the straightforward approach to Hillary. Unfortunately, the straightforward approach is a no-go for comm reasons. So instead of tackling it head-on in a northward drive, we have to skirt around so that we're heading at it more northeasterly. And this means taking on much higher tilt -- nearly 30 degrees, above our comfort level.
(Hillary is, of course, named in honor of Everest conqueror Sir Edmund Hillary. To my surprise, the man is still alive, in his late eighties. Squyres is planning to email him some images of the rock we've named for him. I find this somehow bizarre, as if we were going to send a fax to Erik the Red.)
We're trying to get Spirit into position to IDD, including some very long-term MB and APXS integrations, for the few days that there's no RP coverage because everyone's in Hawaii. We could possibly recover if we need to use tomorrow (Thursday) for a final bump, but that will make Friday hellacious. And if we don't make it on Thursday either, well, somebody's not going to Hawaii, I guess.
The high tilt on this drive is making everyone nervous. After much discussion, Ashitey and I come up with a set of safeguards that should keep Spirit safe while still giving us a good chance of making it to the goal. An even lengthier discussion sells it to the rest of the uplink team. "Just give me time to update my résumé," deadpans Saina.
Courtesy NASA/JPL-Caltech. Our NCAM of Hillary.
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