Spirit Sol 86

Once again, I wake up right on schedule, at least if I were still on Mars time. On Earth time, I'm hours early. I can't get back to sleep, so I just go in early.

Mars time obviously gets under your skin. As we're looking at the downlink data, Mark Maimone looks at one of the MERboards and asks when the SOWG meeting is starting. "18:00? Or is it still at 19:30?" he asks.

"Um, we're on Earth time now," I remind him. "It's at 10."

"Oh, yeah," he says ruefully. "I can't even think in PST any more."

So our plan is to make the big RAT-brush mosaic we didn't get our chance to do yestersol, then drive off. But we don't want to drive off until we're sure the RATting worked. Some RAT-related failures would result in an IDD fault similar to the one we had yestersol; the IDD will stay where it is, won't stow, and so we won't drive. This is what we want. Unfortunately, some RAT failures don't cause this to happen; the rover will blithely drive away without finishing the job. And the scientists don't want that.

Julie says that there's an "OK to RAT" flag we can test in a sequence to have the sequence make these decisions. I don't remember this flag, but I'm not totally familiar with the set. So, good, this gives us a solution: the drive sequences will ask if we're OK to RAT, and otherwise terminate without moving.

It's not until the end of the SOWG meeting that I have a chance to check Julie's assertion. Should have checked sooner. There is no "OK to RAT" flag. We've just built our whole plan around one, though, so we have to scramble to replan.

The new plan drops the long part of the drive; we're just going to back up a meter for the standoff imaging and stay there. I suggest driving forward again after the imaging; that way, if anything went wrong, we can fix it the next sol instead of having to dedicate an additional sol to just driving back up to the rock. (It doesn't take us a whole sol to drive a meter, but for safety reasons we're not allowed to do go-and-touch in a single sol.) Ray likes the idea, but it gets nixed later in the process. So we have to get thisol's sequences right, or it will cost us two sols. No pressure.

We didn't get the MI images of Hawaii. Ray asks why not, and since John is sitting around chatting, I ask him to look into it. It turns out that Mazatzal is slightly closer to us than we thought (this is different from the recent problem of inconsistent terrain meshes), so all of our instrument placements have been ending up slightly higher on the rock face than we'd intended, and we just hadn't noticed. If I'd realized earlier, we could have redone the observation thisol, but by the time I think of it, it's too late to try to get it in.

I finish the RAT mosaic sequence and am about to hand it over to John when I realize that we're about to make a big mistake. The RAT targets were selected in an unusual way, and the normal approach for telling the arm to reach them will put it in the wrong place. I realize this just in time and retarget the whole sequence.

Then I'm done. I stick around for a while to shadow John, since we're switching positions (and I'll end up doing his job even if we don't switch positions, when Mars time rotates around to Earth time). After a while I start to notice I'm getting goofy; it's either the reduced stress level or the fatigue.

It's the fatigue. I go home.


Spirit Sol 85

So this is our first sol on Earth time. At least they've chosen to keep things simple thisol.

In case you can't tell, that's sarcasm. The plan for thisol is to do a complex RAT-brush mosaic, making a big dust-free spot on Mazatzal for the MTES, then back up about 85cm so the MTES can see it. After that, we'll drive about 15m, following the path I worked out in advance yestersol, and then autonav as long as they'll let us.

Or should I say, that was the plan. Then word comes that yestersol's IDD sequence faulted out, and all the images look wrong, and nobody knows why. Since we're on Earth time, nobody's around, so I start looking into the problem myself. I quickly discover that my ability to do this is limited. I have no problem finding the list of warnings and errors that the spacecraft has sent back, but since I never look at them, I don't really know what's normal and what isn't. I write down a particularly suspicious subset and ask for help from Jessica Collisson -- who graciously works on analyzing the problem with me, even though she's on Opportunity and right now they have an anomaly of their own.

This doesn't look good. The rover says one of the IDD tools had a contact switch in an unexpected state. Jessica and I don't know which switches are reporting contact, because we're not experienced enough to decode the data we're looking at, but knowing this much leads me to an alarming possibility. We had a frustrating problem during one of the PORTs[1] when we left the APXS contact switches enabled after opening the APXS doors; a sequence failed that should have worked perfectly, because the switches falsely signaled a contact. The vehicle thought the arm had whacked into a rock or the ground and set an error flag, which caused the rest of the sequence to refuse to move the arm. It turns out that those switches are flaky; they often spuriously signal a contact when the doors are open, so we have to disable them after opening the doors (when we are actually going to place the instrument and therefore might see real contact) and re-enable them when the doors are closed. I know Bob correctly added commands to disable the switches after the tool change, but he forgot to save the state, so when the rover wakes up again, the switches will be enabled. If that's what bit us, we're going to be really embarrassed.

But then I work out, with some relief, that that can't be the problem: the sequence faulted out in the middle of the MB-to-APXS tool change -- before the APXS doors were opened, so the APXS switches were in their reliable state.

Well, that's good, at least. Especially if I'm right, which we still don't really know. But something went wrong.

Bob would know which switch was the culprit just by glancing at the data. I go up his office and don't find him, but Mark Maimone is around, and he has access to the flight software, so he checks it out for me. It turns out, if we're reading it right, that the software was complaining that one of the Moessbauer switches was in contact.

That's fine, except for not making any sense. The tool change stopped in the middle, after the MB had retracted from the rock. The documentation images clearly show the IDD retracted cleanly from the surface; the switches shouldn't be reporting contact.

But as it turns out, Mark got it right (as usual). The MB contact switch didn't release when the IDD retracted from the rock, probably because it was so cold -- because the APXS gets its best data when it's cold, the tool change happened just before dawn, the coldest part of the sol. The cold must have caused the switch to stay stuck closed. (As it turns out, the switch unstuck itself three minutes later, but by then the damage was done. Still, we jokingly claim credit for a self-repairing IDD.) There's a reasonably simple way to work around this, now that we know there's a problem -- it's similar to what we already do for the APXS -- so it shouldn't bite us again.

Best of all, it wasn't my fault.[2]

But this throws our plans for a loop. Since yestersol's sequences didn't execute, we need to redo them today. Which theoretically means it'll be an easy sol, although of course the scientists change their minds about what they want (they take advantage of the fact that we'll be here another sol to stick in another MB integration, among other changes), so we have to change a lot of stuff around. But that's OK, it's what we're here for.

Andy's back today -- he's been on Earth time for a while, and in a sense we're catching up with him. He looks bored, and is casually interviewing people for his book. His publisher wants him to write a chapter about MER for the paperback edition. "I have to describe all of MER in ten pages," he says. "Without sounding bitter."

Sadly, this is Bob's last sol. (Or ... is it? Dah-dah-DAAAH!) I shake his hand. "Pleasure working with you," I tell him, and he says: "Likewise." And that's it. See you, Bob.


[1] An operational readiness test -- one of our many dress rehearsals for operating the rovers.

[2] Sigh. Stuck on that again, are we? Oh, five-years-ago self, won't you ever learn? Well, yeah, I guess you will. But it'll take you a while.


Spirit Sol 84

It's our last sol on Mars time. I spend a lot of the pre-shift time working ahead, trying to assess the terrain for our upcoming drive. Our long-term drive path is blocked by a rock I dub "Combover Pig," so we'll have to go southwest before we can head east to the hills. But there's a bigger problem in the near zone. I try to persuade myself that there's a short path to the other side of Mazatzal, but the terrain doesn't want to cooperate. There's a 15cm rock in the way -- which is not a hazard per se, but there's a 15cm-deep depression on the other side of the rock, making 30cm total, and that's an unsafe combination. I work on some ways to use the terrain against itself, putting one wheel up on the rock and straddling the depression, but there are worst-case scenarios no matter how we go. I'm almost willing to risk it anyway, but I run out of time to look at it without really reaching a resolution.

They used another one of my rover wakeup songs -- Cake's "The Distance" -- on Opportunity. This is because Opportunity set a new single-sol distance record: 48.9m. We're unlikely to surpass that record, but they will.

I've been worried whether we chose the right mesh yestersol, so I'm anxiously waiting around in the SMSA when the pass starts. The minute the images start flowing, John Grant walks up with a huge smile. "You made the right call," he says. The RAT placement was right on the money.

Mark points out that our image of the APXS doors, which is just intended to verify that the doors have closed after an APXS operation, was taken at a higher quality than we think is necessary. It's not a big deal, making only a few KB of difference in the downlink, but this piques my curiosity, and I go ask Justin Maki about it. He doesn't see any reason we need the higher quality either, but it's what they're doing on Opportunity, and it's simpler for everyone if we just let the missions be consistent. And since it's not a significant difference in the downlink volume anyway, we decide to drop it.

But this gets us into a discussion of documentation images. The more documentation images we take, the cooler Stubbe's movies will be. There's an opportunity to take more of them: every time we move the IDD when taking a series of MI images, we have to tell the rover to wait for 15 seconds so that any motion-generated vibration will stop before we take the microscopic image. Is there something else we could be doing in those 15 seconds?

Well, yes, there is. We could take a low-quality documentation image from the front hazcams. Justin does some back-of-the-envelope calculations and works out that we could take a halfway decent image in only 10-20 seconds of processing. And the images would be small -- we have to scale them down so that the rover can take them that quickly anyway -- so they wouldn't generate much downlink data.


Now, how to convince the project to take the images? We start scheming. Justin and Stubbe plan to show Stubbe's movie at thisol's downlink assessment meeting, and that's a perfect time to make the push. Our best idea is to have Justin tell the Spirit scientists, "Oh, they're going to start doing this on Opportunity" -- and then tell the Opportunity scientists, "Oh, we've been doing this for a while on Spirit." There's probably a lot of shit we could pull if we were willing to play the teams against each other this way.[1]

At the downlink assessment meeting, we get the official word that the RAT worked well. Better than that, indeed: the word they use to describe the placement is "perfect." The RAT ground away for almost 3.5 hours, just as planned, and dug 4.1mm into the rock. The yin-yang effect is gone; the surface is now nicely uniform.

Stubbe shows his movie, the history of our rover as seen through its front hazcams. The entire room gets into it in a big way. There are groans when we get stuck at Adirondack (The Time of the Great Anomaly), cheers when we get moving again. Good-natured laughs erupt when the rover's autonav gets spooked by hollows, and it does its little rover dance as it tries to find a path around the perceived hazard. "Hey, there's Humphrey!" someone calls out when the distinctive rock looms. I feel a thrill of pride when my then-record-setting drive goes by, a moment I missed yestersol. As the movie catches up to the present, the magnitude of what we've accomplished here starts to sink in. The movie ends, and the crowd bursts into applause. "That's our high-school reunion," Ray declares.[2]

Stubbe's made a similar movie for Opportunity and shows it as well; it's really cool, but it's not the same. It's somebody else's high-school reunion.

Thisol's IDD sequencing is moderately complex: a five-position MI mosaic of the new RAT grinding, followed by more MI observations on an interesting feature called "Hawaii" -- it looks like a pebble stuck in one of Mazatzal's scallops. After that, I need to place the APXS on the filter magnet, one of the magnets at the base of the mast -- a move that reminds me of placing your thumb on your nose. But it's one of those sols that's complex mainly because of the volume of the work, not because of tricky placements or anything like that, so it goes tolerably well.

Somehow I get drawn into an amusing Shakespeare-themed discussion -- "friends, rovers, countrymen"; that sort of thing. We run out of Shakespeare-oriented rover jokes about as fast as you'd expect engineers to, and I get back to work. But it reminds me of something I worked out early in the mission:

Two rovers, both alike in dignity,
From Pasadena, where we build such things,
From launching pads break forth to neighbors planet'ry,
Where Martian dust makes solar pan'ls unclean.
From forth the IDDs of these two bots
A scientific package springs to life.

On my way out, there's bad news from the other side of Mars: Opportunity is having some kind of anomaly. Sounds like the EEP[3] failed and they lost a sol's sequences; no telling how bad it is. Nothing I can help with, though, so I cross my fingers for them and go home.

Courtesy NASA/JPL-Caltech. Combover Pig. But I couldn't talk anyone else into the name. Is it just me? It totally looks like a pig with a combover, right?


[1] But, of course, we don't. Damn conscience.

"I'll not meddle with [my conscience]: it is a dangerous thing: it makes a man a coward: a man cannot steal, but it accuseth him; he cannot swear, but it cheques him; he cannot lie with his neighbour's wife, but it detects him: 'tis a blushing shamefast spirit that mutinies in a man's bosom; it fills one full of obstacles: it made me once restore a purse of gold that I found; it beggars any man that keeps it: it is turned out of all towns and cities for a dangerous thing; and every man that means to live well endeavours to trust to himself and to live without it." -- Richard III, I.iv.

Also, it makes you not talk one rover team into doing something by telling them the other rover team is already doing it, no matter how cool it would be. Damn conscience.

[2] You can find the video here; direct link to the .mp4 is here.

[3] Shorthand for EEPROM, the non-volatile storage area in which, among other things, the rovers keep command sequences we send them.


Spirit Sol 83

We might start driving tomorrow, sooner than I thought -- if not tomorrow, then the sol after. They still haven't decided where we're going from here, along the rim or straight away from the crater. I start looking through the imagery we have, to see if we've got a safe path in either direction. Neither one looks good.

Opportunity is driving today. Only a few sols out of their crater and they're going to break our one-sol drive-distance record: 48m tomorrow, or so. And they'll better that record on future sols. Before long, they'll set a record we have no hope of breaking. Oh, well. It was nice while it lasted.

I chat with Frank about this for a little while, and about other things. They're going to stay on Mars time a little longer than we are. Frank isn't going to miss Mars time, but I am. I realized one of the reasons why when I was walking in today at 3:30 AM: coming to work at all times of the day and night emphasizes the uniqueness of what we're doing. When we start keeping regular, Earth-time hours, it just won't seem quite as special any more. Frank grudgingly agrees.

"You want to see something really cool?" Justin Maki asks. Who wouldn't? Justin shows us two really cool things. First is an animation of all the MI images that have been taken on Opportunity. The second is even cooler: Stubbe Hviid has put together a movie of all of the front HAZCAM images we've taken on Spirit. The movie incorporates all of our drives and IDD work up to this point -- the last three months of my life, flashing before my eyes. We've packed a lot into those three months.

Mark has solved the visual odometry problem that caused Opportunity to behave so strangely when they tried it. It turns out that the code wasn't properly thinking in 3-D, causing it to think the goal point was closer than it really is. We might get a solution in place and tested in time for us to use it when driving away from here, though I doubt it.

Today's sequencing should be simple: a RAT placement, a bit of IDD work. Of course, it doesn't work out that way. The latest HAZCAM mesh doesn't match up with the old one we've been using; it shows the rock face about 2cm farther away, so that our targets are floating in the air. A third mesh -- this one from yestersol's NAVCAMs, taken on the same sol as the new HAZCAMs -- agrees with the first one. So we end up using the old one, but not until we spend more than two hours arguing about it, comparing older images with newer ones to see if the rover really has shifted position (say, because we slipped off a rock while we were RATting), etc. And in the end we're still not a hundred percent sure whether we made the right choice. If we didn't, tomorrow's sequence will fault out and we'll be here another sol at least. We also don't know why the meshes would have differed, which is disturbing. Those images are critical to our ability to get work done; if we can't trust them, we can't safely operate the rovers.

I get the sequence more or less done and hand it over to Bob, then spend the rest of my time (plus a couple of hours more) planning our exit from here. Meanwhile, "Angry Bob" earns his nickname[1], swearing louder and louder at the software as he finishes the sequencing work. I can't help laughing, but I try not to let him see. I'm going to miss him.

I find myself staring at the navigation images, not making much progress, and decide I should go home and sleep. Surprisingly, I actually do this. On the way out I glance back at my chair and see that someone's posted a sign on the back: "How's My Driving? Call ...."


[1] An abbreviated version of the story: on sol 41, the Spirit team initially planned a go-and-touch -- an unsafe maneuver that would drive and use the IDD afterward, without humans in the loop -- and they called Bob to check on it. This meant they woke him in the middle of his sleep cycle to ask him if they could do something he'd already nixed a dozen times; this time he got extra angry about it and let them know in no uncertain terms. Art Thompson started calling him "Angry Bob" after that, and the nickname stuck.

Now, the nickname wouldn't have stuck if Bob didn't also have the behavior described above, where he'd get increasingly exasperated as the night wore on and expressed that exasperation, shall we say, colorfully. Still, to be fair, the night they woke him to ask about the go-and-touch, Bob was right to chew them out. He'd tried everything else, and it hadn't worked. Chewing them out did work: we never tried a go-and-touch again, until a much later software upgrade made it safe.

For the record, "Angry Bob" prefers to be called "Concerned Bob." :-)


Spirit Sol 82

Ah, a short day. I needed one of those. I have another interview with WBBB, the Raleigh station, and it goes really well. Interviewing with morning shows is strange in one respect: because they're trying to keep the show's energy level high and make their listeners feel good about being awake so godawful early, they laugh at everything you say that's even remotely funny. Even though they're doing it for show reasons and not for me, it helps me see a little of how it is to be famous or powerful. It's like a little taste of that insular world that you always hear that famous people live in. This helps explain famous people. I kind of feel sorry for them.

Yestersol's RAT operation was incomplete. It didn't drill as deep as they wanted, but even more oddly, the left half of the resulting circle is white, and the right half is dark -- a little like the yin-yang symbol. They don't know why this happened, but they're going to do it over.

And in passing, Atmospheres[1] says that we're getting into a time of the Martian year where we may be able to see clouds. Those will be some damn cool images.

Courtesy NASA/JPL-Caltech. Curiously bi-colored RAT spot.

Courtesy NASA/JPL-Caltech. Confirming that Spirit's APXS dust doors are closed.


[1] That is, the subset of the science team that studies the Martian atmosphere.


Spirit Sol 81

Once again, I devote my day to the updated RoSE delivery, implementing the remaining requested feature and packaging a new test release. So much for that.

The extended mission may be extended further than I had thought. All of a sudden, people are talking about Spirit lasting 270 sols (150 for Opportunity). As of Monday -- only a few days from now -- we're on Earth time, and the Earth-time schedule starts at 7AM. I can't do six months of 7AM, but Chris and John will likely take mornings, and I'll take afternoons. Happily, this doesn't mean I'll be RP-2 all the time, because our days will shift in such a way that, after a while, the afternoon shift is doing the first half of the plan, and the next day's morning shift finishes that plan. So the humans will stay on the same schedule and let Mars rotate around us, rather than vice versa.

Once again, the downlink assessment meeting reveals that our Mazatzal exploration schedule has been pushed back slightly; RATting takes a lot of energy, and we'll need sol 82 to charge the batteries. Now the drive starts on sol 85. True to form, the software update has been delayed again as well; it now starts on sol 96. Xeno would be so proud.

They revisit the question of how far to traverse the crater before heading for the hills. The tradeoff is that we'll get less 3-D data on the crater (we won't ever see the parts of it that were initially hidden by the rim itself) vs. getting to the hills that much sooner. The sooner we start the long-haul drive, Ray points out, the more energy we have to drive with; and we might as well start driving while the rover is completely healthy.

"How far around the rim would we have to go to make staying here worthwhile? A hundred meters?" Ray asks. "Less than a hundred meters," Larry Crumpler answers. "Ninety-nine meters?" "Ninety-nine meters, yeah," says Larry.

"So how many people just want to get the hell out of here?" Ray asks. When he rephrases it a little more neutrally, the vote overwhelmingly favors driving to the hills early.

Props to Long John Silver's. Their free-shrimp deal was contingent on our announcing an ocean of a certain size (5 million square km, I think), and we had to announce it by 29 Feb. We announced a smaller sea, and didn't do it in time. But they're giving away the free shrimp anyhow. Yeah, I know it was just a promotion and they were leveraging our fame and whatever. But on the other hand: free shrimp.

I'm just about to leave, but I realize that if I stick around for ten more minutes, I'll be able to be in the meeting with Dr. Elachi, who's going to tag up with us this morning. So I grab a sandwich at the cafeteria and show up for the meeting. As I expected, this turns out to have a bunch of interesting moments.

Mission managers for both spacecraft sum up their progress so far, and the state of each rover. When Matt Wallace says that Opportunity just had their best data pass so far, 104.3 Mbits, Mark Adler jokes, "Spirit's done 108 -- not that we're competing or anything."

Matt also reels off a list of spacecraft subsystems; each one is green, green, green -- until he gets to the Ice Cream subsystem. That one's yellow -- the freezer is starting to get a little low.

And Matt sketches their plan for Deep Sleep. This is their effort to sidestep the problem of the stuck-open heater switch that's costing Opportunity so much energy. Deep Sleep means powering off the bus, and relying on the sun to wake up the rover (when enough energy starts to flow through the solar panels, the rover turns on automatically). They give up a lot for this: they can't do overnight comm passes or science observations. But they also can't heat at night, so the rover will get colder than they'd like. Eventually, around sol 150, it will get so cold that they'll probably lose the MTES. Moreover, it's just a scary strategy. One day they'll turn the rover off and it won't come back on, and somebody will have a bad day.

Justin Maki points out that between the two rovers, we landed 20 cameras on Mars (if you count the descent imagers, which are not on the rovers themselves) -- more than the total number of cameras that had been landed on Mars up to that point.

The crater Opportunity is going to drive to next is called Endurance Crater -- I guess the "Endurance" proponents from early in the mission got their way at last. It's 700 to 800m away, and they expect to cover the distance in about 30 sols, including stops for science along the way. They are really going to be booking.

Elachi tells us we're popular. He was talking to an NBC Dateline producer who told him a story: every morning, the producer's five-year-old daughter wakes him up and asks, "What did the rovers do last night?" They check it out on the Web site every day before he leaves for work.

We have also "had a major impact on the budget," as he phrases it. The Mars program funding is currently $600M/year. That's going up to $1.2B/year in a few years (for perspective, that's more money than JPL got in a year, total, when I started working here). Mars exploration is going to be huge.

So is the moon. We're also kicking off a Lunar Robotic Exploration program, sending a rover every year or two.[1] They'll also be sending landers, but some other center (or maybe LMA) is going to do that (though we'll still have a hand in those missions, supplying scientific instruments for them). We'll be doing the rovers. "Whenever you're finished here, you'll have lots of opportunities on the Lab and in the Mars program," he says. Not bad, considering that -- as I had heard rumored before -- at one point we were this close to NASA HQ canceling one of the two rovers. (This was when we needed extra money for the flight software. Their idea was to cancel the second rover and use the cost savings to fund FSW instead. To their credit, HQ decided to come through with the money, and the result was a rover in Meridiani -- the one that found the water. Another lesson learned from that: they're now thinking about doing two rovers, not just one, for MSL.[2])

Bob Deen asks whether we'll be flying a MER-C and MER-D -- two more MER rovers. No, says Elachi, but we have looked into reusing some of the technology for the lunar rover missions. It occurs to me that they could also reuse the acronyms: Moon Exploration Rovers, here we come.

Elachi says we've raised the bar for other missions, including Cassini. We had "six minutes of terror"; Cassini will have "an hour and a half of agony."[3]

Elachi downplays reorganization fears. From 2000 to 2010, JPL will be launching more missions than it did in all of JPL's 40 years before that, he says, and it's appropriate to look at whether we need a reorganization to handle that. We won't be splitting groups or sections but may move the sections around at a division level.

Somebody asks what mission success criteria we haven't met yet. We just need to put a few more meters on the wheels and hang in for a few more sols. "We do have things we need to do for NASA," Elachi says. "But I can tell you that in the eyes of the world, you have already achieved full success."


[1] We are? What the hell happened to that plan? That would be awesome! I want my flying car and my goddamned moon robot, already.

[2] Grr. Don't get me started.

[3] During SOI, their Saturn Orbit Insertion.


Spirit Sol 80

I spend basically the whole night working on the new delivery of RoSE, and am able to cut a preliminary release (missing only one feature, which I'll do tomorrow) for testing.

I interrupt this only for the downlink assessment meeting. The MB PUL reports some surprising results from their instrument. We don't seem to see through the dust on Mazatzal -- they see more Fe3+, not less, after brushing.

Someone also has a presentation diagramming rock layers, from the outside in:

Loose mantle
Cemented coating
Rock alteration products (friable)
Moderately altered rock (indurated)
Unaltered parent rock

The RAT can in principle drill all the way down, but so far we're seeing surface phenomena only. They plan to spend more time here than they originally scheduled; now the drive is set to start on sol 84 or 85. This is partly because this will have to be a recovery sol: the APXS doors did not fully open on our latest placement (roughly, it turns out we have to push a little harder on them than we've been told to), so they need to redo the work. As a result, they won't RAT tomorrow; tomorrow will be devoted to MB/APXS and remote sensing. By the time they discovered this APXS problem, the next sol's APXS sequences were already set, so they'll have two sols' worth of data to redo.

Basically the entire extended mission will be devoted to exploring the Columbia Hills. Of course, first we have to get there, or try to. They're planning 60 sols, plus 30 contingency sols, for that. Over the next few days, they'll try to work out how long it will take to drive there, and how long Spirit is likely to last. This will tell them how much time they have left over to do science at random targets of interest along the way.


Spirit Sol 79

In my copious free time, I've been hacking on RoSE to add features that they'll need for the extended mission. So far, there hasn't been a delivery date, so I've just been working on the changes when I can. Today a delivery date crops up. They want to install it Monday.

That means I'll need every spare minute to finish the work. So I don't have time to check out an alarming observation about the failed Mazatzal drive. Mark Maimone points out that the tracks show that we passed only about 60cm from a rock called "Skull," much closer than we should have. The planned drive had about 1.5 to 2m of clearance. Skull was a large rock; if it had been a little taller, this problem might have damaged the solar panels. The positive spin on that, I guess, is that things could have been worse.

I do take time to go to the downlink assessment meeting, though. The coolest part of that is a "show and tell" moment: one of the RAT guys passes around a prototype of the RAT. It's cool to be able to hold it in my hand, press the contact switches against my palm to get a genuine feel for the instrument.

I also go to the post-SOWG science talks. Ben Clark tells us about "The Universal Soil of Mars." The soils and rocks have most elements the same; only sulfur, chlorine, and maybe potassium differ. Adirondack and Humphrey are made of virtually identical material. In order to tell whether this is only a surface phenomenon, he argues for a deep RAT grind. It might also help to do a progressive brushing: do a light brush, measure the spot afterward, then brush a little more and measure again, and so on, to see how the results change as the dust layer thins and eventually is removed entirely.

The really interesting presentation is Geoffrey Landis's exploration of the "Proposed Spirit Electrostatic Discharge Campaign." There's a lot of electrostatic charging on Mars, which comes from the sand grains being rubbed together by wind (similar to rubbing a balloon) and from the solar UV. Some of the dust adherence to rocks may be a result of this electrostatic charging.

However, because the air pressure is so low, the fields will tend to discharge easily. The ever-present dust devils, for instance, likely have strong electrostatic fields and may discharge them continuously, much as happens in tornadoes on Earth. Similarly, winds blowing into Gusev from the Ma'adim may stir the sand enough to cause electrostatic discharges. This stirring would happen at night, as katabatic winds (caused by nighttime air cooling) come whistling down the Ma'adim river valley. He suggests that we try waking up at night and looking for the glow.

It's even possible, he says, that the RAT brush would produce a friction charge. If this is permitted, we could try running the RAT brush at night and watching for discharges into the soil. Even the rover's own motion may charge the dust, simply by compressing it, though it's not clear to me how we'd test that.

Electrostatic buildup on Mars is not news. The rovers have electrostatic discharge needles for precisely that reason. (He shows a picture of the rovers during assembly, when these needles had an attached tag: "F#@!ing Sharp Hardware -- Keep Hands Out!")

Seeking and measuring the electrostatic discharges, he concludes, might help with future mission planning. There might also be a good science reason: electrostatic forces may contribute to weathering; if we measure them, we'll know more than we know now.

The science plan for tomorrow has to be radically curtailed late in the process. It turns out we have significantly less energy than predicted, and they need to conserve power for the RAT. Jeff Norris gets visibly stressed out and depressed as he cuts more and more science observations in order to get energy usage down far enough. I know he doesn't look forward to reporting what didn't make it into the plan. At one point, when he's waiting for a remodel to complete, I lay down a challenge.

"I dare you, after you list the things that didn't make it in, to say: 'But I do have some good news ... I just saved a ton of money by switching my auto insurance to GEICO.'"

This gets a big laugh from him. "You can't just dare someone to do something like that, though," he says. "You have to provide some kind of reward."

"Dude, the reward is to have done it!"

He laughs again. But when the time comes, he doesn't say it.


Spirit Sol 78

I get to thinking while driving in to work. We haven't screwed up many drives, but the ones where we've had the most trouble have been approaches. Traversing many meters in terrain where you'll slip an unknown amount, and having to end up in a zone only 10 or 20cm wide, is a recipe for failure. Even in this terrain, where we knew we were slipping 5-10%, given the length of the drive, the uncertainty in the amount of slip exceeds the size of the target zone. So we were, essentially, relying on luck. Gambling. And we lost.

The Mazatzal approach was just one example; we had a similar issue when approaching Humphrey, but it so happened that that drive was planned as a two-cycle drive for other reasons, so they had a chance to recover on the same sol. I decide that the next time we have an approach sol, I'm going to insist on either visual odometry (which we currently can't use because of the irreproducible problem we had with it on Opportunity) or a two-cycle drive. It might take some selling, but I'm determined. I don't want another drive to go wrong, and it's better to take our time on the approach sol and do the job properly than have to waste one more damn sol recovering.

The pass comes, and I'm relieved to see that we're just about exactly where we wanted to be. I guess I'd be another 5 or 10cm closer if I could, but we can still reach plenty of the rock face from here, including RATtable spots. It's not perfect, but we can do the work we need to do. Not what I was hoping for. But you know what? Fuck it. I decide to consider this a victory.

I look at the front HAZCAMs with Dave Des Marais and Craig Leff. "So, is this a 'white rock?'" Craig asks. Dave equivocates on that point, but adds that the politically correct term is "light-toned rock." "Yeah, but the phrase 'Light-Toned Rock Mafia' just doesn't have the same ring to it," I say.

Craig asks if the rock is reachable, and I tell him we should have good coverage on the lower half of the rock at least. They should plan to RAT. "Short drive, huh? Piece of cake," he says. If he only knew.

"Holy shit," says Craig, looking closer at the picture, "there's a huge crater right next to us! Did you know that?"[1]

Despite the fact that we're in a decent spot relative to the rock, I still feel kind of depressed about it. Finally I decide I'm just not going to feel that way: I decide that today is going to be a good day, damn it. The Buddhists say that if you put on the face of a tiger you gain the courage of a tiger, or something like that.

I like tigers.

At least I'm not the only one who ever screws up. For days now they've been trying to delete some unneeded on-board directories; the sequence will take about thirty minutes to run and needs to execute early in the morning, which cuts into the IDD work. For one reason or another, it keeps not happening. Today Art has to report at the downlink assessment meeting that it didn't happen again: they somehow forgot to uplink the sequence yestersol. So they'll need to do it again, and structure the IDD work accordingly. Is it bad to feel relieved by this, I wonder? It's not quite Schadenfreude, but it still doesn't feel like the right attitude to take. Well, I can't help it. It does make me feel better, a little. Maybe.

There seems to be growing support for truncating the crater traverse. LTP's presentation includes two positions from which we might leave, one of them relatively nearby, the other 100m along the rim. But we've got a lot of work to do at Mazatzal before we go. We'll spend the next sol or two inspecting the original, undisturbed surface of the rock in three separate locations. Then we'll brush those same three locations and IDD the result, then grind one or two spots and IDD the result of that. We'll be driving again by sol 82 or so, and we'll drive for maybe a week before we have to stop a while for the flight software patch upload.

As Ray observes, though, the patch is being delayed at a faster rate than we're approaching it. Mark Maimone has taken to calling it "Xeno's software upload." That's a reference to "Xeno's paradox," after the Greek philosopher, who said this: In order to cross a room, you first have to get halfway across the room. Then you have to cross half of the remaining distance. Then you have to cross half of that remaining distance, and so on. Ergo, you can never reach the other side of the room.

Incidentally, Xeno, never one to leave a good idea alone, formulated a related paradox, which in light of Ray's observation might be more appropriate. It starts the same way: In order to get across the room, you first have to get to the halfway point. But, Xeno points out, in order to get to the halfway point, you first have to get halfway to the halfway point. But first you have to make it halfway to that point, and so on. Not only can you not cross a room, Xeno concludes, you can't even get started.

For an ancient Greek, Xeno knew a lot about software development.

Alian Wang gives a short presentation titled "Attacking Mazatzal," in which she lays out a strategy for the science we should do here. My favorite part of the presentation (after its title) is where she argues, "If we want to do this rock and get some idea about its coating, we should do the lower part of the rock." Which is the part we can reach. Phew.

At the end of the meeting, Tom Economou introduces a new pair of visiting high school students -- part of the Athena Student Intern Program -- Brianna and Filadelfo. They're from a Chicago suburb (Wheaton), and since I went to nearby UIUC for grad school, I go introduce myself. It turns out that Brianna is going to UIUC in the fall. Clearly an intelligent young woman.

Also, their high school mascot is a tiger. Freaky ....

Word on the street (well, OK, in the SOWG meeting) is that as the project downsizes, they're going to keep anyone who wants to stay. This is good news; they'll have to drag me out of here kicking and screaming.

I set a new personal record, finishing the sequencing -- at least getting the sequences into deliverable shape -- before the end of the SOWG meeting. But I have to change it afterward, when the scientists change their minds about the targets they want to go to. They'd chosen three targets -- California, Arizona, and New York -- and they decide to scrap New York for a target in between Arizona and New York. They need a name for the target. "What's the name of a state halfway between Arizona and New York?" someone asks. In honor of our visiting students, I suggest Illinois, and the name sticks.

Changing the target doesn't change the sequence much, and I end up with plenty of time to spare. "You look underchallenged today," says Art. "It's a nice change of pace," I tell him.

Indeed, I could leave early, except that I want to stick around for Opportunity's second try at exiting Eagle Crater. About noon I go to the SMSA again. Much the same crowd is there, and today we're joined by an NPR reporter as well. I think Frank and the other Opportunity drivers are itching to drive, drive, drive. Frank says something about looking forward to trashing some of Spirit's records. Despite their achievements, I guess they feel they've been taking a back seat to us in that respect. "Scott's been cordial about it, but Chris needs to be schooled," he says with an evil grin. To my chagrin, Ashitey reminds him of the one time I wasn't so cordial. Ashitey and Bob were discussing which rover was likely to live longer, and I said Opportunity would definitely outlast us -- "I mean, you guys have hardly even been using your rover," I said. Oops.

This time the drive succeeds: our next picture from Opportunity shows it on level terrain. They're out! Frank breaks out a bottle of champagne he brought from home, but Jim Erickson interposes himself between Frank and the media guys. "Not on camera," he says, and Frank sneaks the bottle back into his bag. Which is weird -- they were fine with the champagne yesterday. Maybe they got some flack over it, or maybe there's different media here today.

Anyway, this little flap doesn't dampen anyone's spirits (so to speak) in the least. The pictures show a weird, gently rippled landscape extending as far as the rover's eye can see. There's one rock in view -- "Bounce Rock," which they hit when landing; bouncing off this rock is what knocked them into Eagle Crater.

"In a way, it's like you've got a whole new mission," I say. "MER-B part B, or something."

"Yeah, and we've already discovered water," Frank adds.

Courtesy NASA/JPL-Caltech. Much better this time. Not perfect. But much better.

Courtesy NASA/JPL-Caltech. This time, Opportunity's out!


[1] That still cracks me up. I miss working with Craig.


Spirit Sol 77

I wake up on the wrong side of the bed and arrive at work in an uncharacteristically foul mood. My mood doesn't improve when I see the results of the drive. We didn't make it.

It looks like we slipped twice as much as predicted; we're short of our planned position by maybe half a meter. We wanted to end up where we could IDD Mazatzal, including RATting. But the rock is barely within reach of the IDD, and we definitely can't RAT it from here. So we'll have to spend another sol getting where we really need to be.

Well, I'd been wondering what it would feel like to blow it. It doesn't feel good. In fact, it feels absolutely fucking rotten. In retrospect, I could have lived without knowing that.

This makes the downlink assessment meeting an uncomfortable place to be. I feel like everyone's being careful not to blame me. But it's my fault. I should have fought to use visodom; this would have cost us a lot of time and power, but we'd have pegged the drive. Or maybe I could have found a better approach angle, or something. I should have tried harder.

We'll be here three or four sols. Their commitment to RAT this rock is unshaken, though thanks to me that won't happen as soon as it might. (Bah.) We'll probably treat Mazatzal the way we treated Humphrey: brush off several spots to get the effect of a single big spot we can effectively MTES, IDD those spots, and grind one or two of them more deeply for closer inspection.

Is this a "white rock" of the sort the White Rock Mafia has been agitating for us to investigate? Nobody seems to have a firm opinion. "Can't we just say it's a white rock and be done with it?" someone asks wearily.

The more I sit in the meeting, the less it seems to me that anyone else really is upset about our (my) failure to reach Mazatzal. I'm still deeply upset with myself, but I seem to be the only one. Dave Des Marais even puts a positive spin on it: "In a way, this is ideal for Steve [Gorevan, the RAT guy] because he'll have full control over the approach."

I later sit down with Dave and Steve to talk about exactly where they want to go from here, and Dave goes off on a fascinating explanation of why Mazatzal captured their interest. Its large size and unusual shape were initial factors -- different is good -- but it also has a "sugary" texture, indicating that it might have formed slowly. This would mean that it's coarse-grained and hence a good, relatively soft target for RATting. It might also contain chunks of harder materials -- probably not quartz, but maybe something harder than plain basalt. Finally, Mazatzal was likely spat out of Bonneville Crater when the crater was formed, and has been sitting right here since then. During all those millions of years, the wind has screamed across the crater, picking up dust and whipping it against Mazatzal, which caused its weird, scalloped appearance. (The geologists' term is "ventifact": a rock that's been faceted and polished by wind erosion.)

The plan for tomorrow is to inspect the soil next to Mazatzal -- its "skirt" or "apron" (depending on whom you ask) where the soil is coarser and darker than elsewhere. Then we'll drive to a nearby position -- toward the other end of the rock (the part that looks to me like the fish's head), and angled more directly towards it, and a little closer. If we could just push the rover half a meter to the left and about 30cm closer in, that would be perfect.

I really want to get this drive just right, especially after today's, ahem, disappointment. It should be a simple drive -- but yestersol's drive should have been simple, too, and look how that turned out. So I work on the IDD part of the sequence during the SOWG, so that I'll be able to focus on the drive afterward. I'm finishing this up as the meeting ends, and as people are filtering out, one of the PULs, Miles, approaches me. "I forgot to congratulate you on that excellent scuff drive the other day," he says casually. Miles is a good guy.

Either Bob is losing his enthusiasm or I'm getting better at the IDD sequencing, because he makes fewer tweaks to this sequence than he's made to any others. I hope it's that I'm getting better, since he's leaving MER to work full-time on Phoenix at the end of the nominal mission, just a couple of weeks from now. That will be a shame -- not only because I literally sleep easier knowing he's looked over the IDD sequences, but also because I'm going to miss his dry humor. I think I'm even going to miss his bad moods, the ones that have earned him the nickname "Angry Bob." Because I don't think he really means it.

The name "Mazatzal" is still causing problems. During a meeting in which people keep fumbling the name, one of the UVLs asks plaintively, "Are we gonna stay here for a while?" Everyone laughs because we know what he means: if we're going to keep talking about this rock, we need to give it a name we can pronounce. "Maz" is the current leading candidate.

I'm done for the sol, but I stick around anyway, because Opportunity is climbing out of its crater today. My shift ends about 8AM, but the comm pass isn't until about 12:30, so I play backseat rover driver for a little while, then fiddle with some other work.

When the time comes, I go sit in the SMSA. It's a happy place; I haven't seen it like this since the landings. Most of the mission managers are there, along with some media, and seven of the eight rover drivers -- including Frank and Brian, who built the drive sequence that will take Opportunity out of the crater.

When the pass comes, our first indication of the results is just a number on a DMD display: Kevin Burke reports that the rover is on flat ground. Either it climbed all the way out, or it slid all the way down to the bottom (just kidding, that wouldn't happen), so we all cheer.

Then the images come in. We applaud again before realizing that they don't look quite right. They're tilted, which they shouldn't be if the rover is flat. We spend some time trying to figure this out before we deduce what happened. Kevin reports sheepishly that he'd read off the wrong number. The pictures don't lie: the rover is tilted. Opportunity is still in the crater.

Oh, what the hell. We're all celebrating anyway. Matt Wallace breaks out champagne and serves it to the rover drivers after a little speech. "Here's to trying again tomorrow," he concludes.

This goes on for some time before I notice the contradiction in my own attitude. I'm still deeply depressed and angry over the failure of my drive, but I don't feel anything like that about Opportunity. Quite the opposite: I'm genuinely happy that they got as far up the rim as they did, and I'm looking forward to their success on the next sol. Sometimes I wonder how my life would be different if I went a little easier on myself.

Courtesy NASA/JPL-Caltech. Opportunity didn't quite make it after all.


Spirit Sol 76

Our downlink data is delayed by some kind of ground system glitch. The glitch clears up to show us a flattish, whitish rock just in front of us, and a much more interesting fishlike rock a few meters away. It reminds me of a coelacanth or something. So we're going to MI the nearby whitish rock, then drive to the coelacanth. This all fits neatly into one of the scientists' sol templates (a "D-type," or "dirt-type," sol).

The "coelacanth's" name is Mazatzal, which is the name of a group of mountains in Arizona. Nobody can get this name straight; all night, people keep calling it "Mazatlan," "Marzipan," etc., until it becomes a running joke. I really wanted them to call it "Coelacanth," but that would have been worse. I end up attaching a picture of a coelacanth to my uplink report anyway.

Our odometry total is 459m, plus the 25m or so we traversed today. Added to Opportunity's 115m, we are just under 600m combined.

The time the scientists save planning by using the new sol templates gives them a lot of time to sit around arguing. They must love them.

To kick off the discussion, Jeff Johnson shows a PANCAM spectrum of Bear Claw, the scuff I helped make when I was last on shift. It's a beautiful, beautiful picture, and the science information revealed by the scuff is no less interesting. The small rocks we see around us seem to be made mostly of the same stuff as Adirondack. The material inside the Serpent drift, the stuff revealed by the scuff, is something different -- they don't know what yet -- and the dark deposit on the far wall of the crater, with its "mystery feature," is something in between. That's surprising, since they expected Serpent's insides to look the same as the crater deposit. They haven't yet compared the data to the trench results -- "but that's a good idea," Jeff muses, "we should do that."

The scar, however, does show some evidence of the mystery feature, which is also surprising: why would the stuff (whatever it is) be in some of these identical-seeming drifts and not in others? At this point, there's no answer.

At the SOWG meeting, Art has some bad news: the rover appears to have lost one of its PRTs (a temperature sensor). But he compensates with good news. No, it's not that he just saved a bunch of money by switching his auto insurance to GEICO. It's that the ICFA is at 90% capacity. The ICFA, he explains, is the Ice Cream Freezer Assembly.

Today's IDD work is straightforward; it's the drive that's going to be a pain. Mazatzal is only a few meters away, but we have to do a little zig-zagging in order to get there from here. But that's not such a big deal; what makes this drive difficult is that we don't yet know how we're slipping in this terrain. So we can't be sure whether the drive will overshoot, and overshooting will be a problem, because the rock we're driving to is obstacle-sized: it wouldn't be safe to drive over it. And, because they naturally want to IDD the rock when we get there, we have to end up in a fairly narrow range: close enough to reach a range of targets with the arm, not so close that we can't even safely unstow the arm without whacking the rock -- or, worse, not so close that we actually drive onto the rock. Even if we had a good slip analysis, there would still be significant uncertainty, because that's just a probability; it changes based on how rocky the terrain is, for instance. We do the best we can.

On my way out I run into Ted Specht, who wrote some software we ended up not using. Back when that used to happen to me, I always used to wonder why. Why would people ask for things and then not use them once I delivered them? Now I know: on a flight project, things move so fast that you've got to keep moving with them. Ted's a multimission guy; if he'd been 100% on MER, we probably would have ended up using his stuff. But he had other obligations, and by the time he delivered his solution, we had other solutions in place. Fortunately, he's still glowing from his honeymoon in Croatia. I don't think he minds at all that we didn't end up using his code. Or even notices.

Courtesy NASA/JPL-Caltech. Mazatzal (above) totally looks like a coelacanth (below, c/o Wikimedia).

Courtesy Alberto Fernandez Fernandez. Image licensed under a Creative Commons Attribution ShareAlike 2.5 license.


Spirit Sol 75

I'm off shift, which means I spend my time hacking on RoSE instead of doing the glamorous work.

We've traversed another 34.3m around the crater, which is a pretty good drive for this rocky terrain. They also scarred a drift as they drove by it -- driving along a drift such that the wheels on one side rode through it, periodically wiggling the wheels and correcting for yaw. They took pictures of the scar before moving on; this should make for some interesting science.

It's not clear how much farther we'll travel around the rim before heading for the hills. They're looking into what data we need to gather, via remote sensing, on the Columbia Hills before we have to pause exploring while they upload the new flight software.

It occurred to someone that autonav won't see a certain type of obstacle as a hazard: a tall, thin spike. Despite the fact that nobody has ever, ever observed such an object on Mars, we get an official directive not to plan autonav drives into an area unless we can rule out the existence of such a hazard. In most cases, if we could see that well into the area in question, we wouldn't rely on autonav; we'd use blind driving instead. The new directive is very stupid. I think Mark instigated the concern about it as a way to drive the project to install the updated flight software, which would detect Martian beanpoles as a hazard.

The best news of the day, I think, is that our big picture is back. I think somebody must have taken it to LPSC. In any case, Mars is outside my office door once again.


Spirit Sol 74

Interestingly, the scuff-drive ended up driving the rover's right bogie to the hardstop. While climbing over one of the rocks as we backed up, the bogie (the rear part of the rocker-bogie suspension) was angled way up. No harm resulted to the vehicle, and as Rich Petras points out, this is something that rocker-bogie suspensions will do from time to time, and none of our modeling tools can predict it well. So I didn't do anything wrong. But it's a little freaky to see.

I finish implementing a new RoSE feature just in time to go to the downlink assessment meeting. I'm not really clear on how far they drove yestersol, if at all, but they did some remote sensing on White Elephant. Steve Ruff, reporting the MTES results, deadpans: "It looks like a dusty rock." The RAT guy, Steve Gorevan, says White Elephant looks "eminently RATtable," an important consideration for characterizing white rocks. Arvidson seems to want to skip White Elephant, though, feeling that it will slow us down too much. We're not really sure if the terrain is navigable (because we don't have terrain meshes yet), and he wants to put more meters on the wheels.

One thing they might want us to do while putting meters on the wheels is to deliberately drive one side of the rover along a drift, leaving a big scar for them to image. There are problems with doing this (it guarantees slippage, which means uncertainty in our positioning, and that uncertainty is multiplied for a longer drive). But it sounds like a cool thing to do.

Just before the meeting ends, Ray reports that "at LPSC, we were heroes." Steve Squyres stood up and got a huge round of applause before he even said anything. The room was packed wall to wall -- people were standing in the aisles and along the walls; you couldn't enter or leave. "I haven't seen such excitement since the Viking lander missions," he says. "Even grumpy old greybeards were ooh-ing and aah-ing."


Spirit Sol 73

Once again I have a lousy night's (actually, day's) sleep. I keep waking up, thinking of ways the drive is going to fail. There are a lot of them. We didn't correct enough for slip. Or: did we really analyze the depression ahead and to the right of us? Could any nasty surprises be lurking there? Or: if we slip too much as we drive downhill, we'll end up climbing that 20cm rock ahead of us instead of stopping short of it, and if there's a depression on the far side, we could get high-centered on it -- with the rock scraping the rover's belly, and the rover unable to gain enough traction with any of its wheels to crawl back off. Of course, this would mean that our imaging was badly wrong, and our simulations were badly wrong, and our slip estimates are badly wrong. But apart from that, it's very likely.

I obsessively check the flight director's report while getting ready, and am considerably relieved to read that we drove the expected distance and have a scuff mark in front of us. Is it reachable from the IDD? Did we nail the mid-drive imaging? The report doesn't say. But when I get to work and see the results, I'm shocked.

It's perfect.

The scuff is nearly dead center from our final position, with good chunks of it in the IDD work volume. (In fact, maybe all of it is in the work volume; the tool that does the preliminary analysis has some limitations that the shape of the scuff might be exposing.) And the mid-drive NAVCAM, which is a bellwether for the other mid-drive imaging, couldn't be better. The main body of the scuff is right there in the middle of the image. While I'm gaping, John Grant says: "Let me be the first to congratulate you on a perfect drive." When he left last night, he just wanted us to end up somewhere near the scuff. And we executed perfectly. I don't know if it's relief or disbelief, but I can't stop looking at it.

I know I say this all the time, but seriously: I worry too damn much.

I'm not on shift today, Chris is, so it will be his job to IDD the scuff (which has been named "Bear Paw"; targets in it are getting names like "Panda" and "Grizzly"). So I get to wander around and unwind a little before the meetings. Because I didn't come in the usual door, it's not until now that I notice that the beautiful big picture they hung outside our office is gone. Nobody seems to know where it went. Only the tape remains.

But there are a couple of new things posted up in other areas. A copy of the Weekly World News, with its cover story of strange cat-like creatures detected by the Mars rovers, is a favorite. This has been posted in the SMSA (outside of camera range), next to some supermarket flyer advertising, among real items such as $1 calculators, "Mars Water" -- direct from Mars -- for the low, low price of $999,999.99 per gallon.

I take some time to catch up on the images from both rovers. Just as I finish, I manage to delete all the images I've saved for the last week or so. Fuck! I have to go back through the database, digging around for the images I'd liked enough to save. Fortunately, I still have the filenames in an open xterm, and I'd named the files descriptively enough that I'm able to find most of them again.

Correcting this stupid mistake makes me a little late for the downlink assessment meeting. It turns out that Serpent's inner material, while considerably darker than its exterior, is not the same stuff as in the crater after all, so there's little reason to stay. Although, after some debate, they do decide to do a touch-and-go here: they'll look at the inner material quickly and drive on in the afternoon. The target of the next drive, or set of drives, will be -- assuming they can get there from here -- one of the fabled white rocks. This one's been named "White Elephant," and I can't help thinking this is an expression of the attitude the non-members of the White Rock Mafia have toward their White Rock Mafia colleagues.

The composition of Serpent's interior was one surprise. Serpent's outer layer gives us another surprise. Serpent looks like a miniature sand dune (technically, a ripple); we expected it to be soft. But the outer layer is an indurated crust: it's composed of sand, but the sand is somehow cemented. I ask Craig Leff what could be causing that kind of effect; he doesn't know. On Earth, he says, something like that is usually the result of evaporating water. Here, nobody knows what could be causing it.

Courtesy NASA/JPL-Caltech. Holy smoke, it's perfect!

Courtesy NASA/JPL-Caltech. Rover's-eye view from our final position, with the Serpent scuff right in front of us, ready for us to IDD it.


Spirit Sol 72

I wake up a couple of hours early, in a near panic. I had completely forgotten that our previous drive had timed out, which means we would have had a goal-error flag set. Mark didn't mention this in his hastily written downlink report, so we didn't clear the flag in this drive sequence, which means the drive won't happen. I dislodge Zenobia, log in from home, and check the telemetry -- only to find that the goal-error flag wasn't set after all. (Which must be the actual reason Mark didn't mention it: there was nothing to mention.) I don't understand this, but I'm so relieved that for the moment I don't care. I actually manage to get a little more sleep before I have to get up.

(It turns out later that there's a good explanation why there was no goal error. At the end of our last drive, the rover timed out because it was back-and-forthing, trying to find a safe path. It happened to time out after a backward move, which left a little extra space in front of it. The sequence cleared the timeout error, enabling the rover to complete the final stutter-step into the small safe zone, without producing a goal error. If there had been such an error, Mark would have mentioned it and we would have cleared it as a routine matter; we do that all the time. So everything was fine. You'd think my subconscious would have recognized this pattern by now, instead of waking me up all the goddamn time.)

My badge is working again. I stuck around for hours yesterday, just to find out that Security couldn't help me at all. The project sent them a list of people whose access was supposed to be revoked and mistakenly included my name on it; apparently, this kind of thing happens all the time. And I'm far from being the only person it happened to this time: I keep having to open the door for other people whose access was mistakenly revoked along with mine and hasn't been restored yet.

Today's drive didn't quite complete, but we got a heck of a lot closer than I expected. We made it to the far side of Serpent and turned to face the bedform; that's the good news. The bad news is that the rover saw a 10cm rock with a depression behind it, and interpreted this as a 30cm obstacle. (Not unreasonably, actually; the rover could actually end up in trouble if it tried to drive over this in just the wrong way.) This exceeds the maximum obstacle size, so the rover refused to perform the final approach. We ended up 85cm short of our destination. Considering all the things that might have gone wrong, this is not bad at all. And there wasn't anything we could have done about it in advance; from our starting location, we couldn't see this terrain well enough to have avoided the problem. Just one of those things.

While we're looking at this, John Grant comes by to alert us to the day's likely plan. It's always something new. They want us to drive up partway onto Serpent, make a big scuff mark (not really a trench, just enough to scrub off the outer dust layer), back up so they can PANCAM/MTES/NAVCAM the scuffed area, and then drive forward again so that the area they just imaged is in the IDD work volume.

What makes this interesting is that we have no idea how much we'll slip in the process. So we can't accurately correct for slippage in advance. Mark suggests using visual odometry, a feature where the rover watches how objects in its visual field change position as it moves, and updates its own internal position estimates based on the result. This is really how humans work: when you're "navigating" as you walk, you trust your eyes more than you trust your feet. The rover normally trusts its feet (wheels), because it thinks so slowly. But when you need precision and can't correct on the ground, visual odometry is the only way to go. We haven't done this on Spirit before, but Opportunity has used it to good effect.

The big news in the downlink assessment meeting is that we've achieved mission success. We were waiting to rack up 60 sols of science ops. That was delayed by the Bad Thing[1], but we've now hit the goal. From here on out, we're gold. More good news: Lutz reports that yestersol's MI images (the ones we took after the gunslinging) look fabulous -- judging from the thumbnails, at least; we'll get the full frames in the overnight pass.

The plan shapes up to be pretty much what John Grant said it would, but there's a lot of debate over exactly what we want the rover to do to Serpent before we poke at it. Do we just want to drive onto it, then drive back off? Or should we wiggle the wheels, or run one of the wheels in a trench-like operation to scoop material out of it? Do we want to make one track or two? John suggests that everyone who cares about the details discuss the matter with me after the meeting, then ends the meeting itself. I accumulate a group of about a dozen scientists, who debate amongst themselves for a while before deciding that anything I do that scrapes away the upper layer is fine. Since we're already more or less lined up with Serpent, we should be able to just drive almost straight ahead onto it -- this will roll the left wheels over the top of the bedform -- and drive straight back off. In order to IDD the resulting scuff mark, we'll have to shift the rover to the left, which there's no very good way to do -- because the middle wheels don't articulate, we have to turn and drive and turn, and this accumulates uncertainty. (This maneuver later becomes known as "The Translation Dance.") But it should be OK.

This is starting to look like a nice, straightforward plan. So naturally it goes to hell. I'm building the sequence in the SOWG meeting when I realize that if we carry out that plan, we'll end up with the rover straddling Serpent. Which in itself is fine; Serpent isn't that tall where we are. The problem will be that we won't be able to use the APXS. To use the APXS, you first have to open its dust doors, which you do by pressing the instrument against a hard surface; this triggers a switch that pops the doors open. Soil isn't firm enough to cause this to happen (and we'd get the instrument dirty anyway, if we tried), so when using the APXS on a soil target, we instead bring it underneath the rover and press it up against the rover's "chin" (technically, a calibration target called the CCT). But when doing this, the IDD needs a lot of clearance under the rover. And Serpent is too tall. If we try to open the APXS on the CCT while straddling Serpent, we'll end up dragging the RAT (the instrument opposite the APXS) through the dirt, which is Very Bad.

We can't fix it by backing off farther, because there's a rock of about the same size at Serpent's tip. If we back off farther than that, we can't reach Serpent any more. The scientists consider whether we can open the APXS before driving and just leave it open overnight, but this violates a flight rule and nobody feels very comfortable with it. We'll have to find another answer.

Fortunately, I paid attention to the earlier discussion and I know what their general goals are, so I have an alternative to suggest: drive around to the side of Serpent and scuff it from there instead. I'd previously rejected this idea because it made things too complex (the drive itself is not complex, but the more driving we do here, the more uncertainty we have about the results), but I no longer see an alternative. We go down to the sequencing room and I start planning it.

Now there's another problem. The instrument reps need to know where to point the cameras to get images of the scuff marks. But we don't really know where those are going to be, because, again, we don't know how we're going to slip. We don't know exactly where the rover is going to intersect with Serpent, and we don't know how it will yaw when scuffing, and we don't know how it will slip afterward. All of these problems combined make it impossible to pick a precise target in advance.

This leads to an overly complicated discussion, made worse by the fact that every time we get all of the participants up to speed, someone else overhears the content of the discussion and wants in, and we have to start over. I start to get really frustrated: time is running out, and there are too many people offering too many suggestions (often ones we've already dealt with, before that person came into the conversation).

At last I see the answer. It's one of those things that's easier to see if you're a programmer. We've all been thinking in terms of absolute positioning -- predicting the spot where Spirit will cross Serpent -- but the answer is relative positioning. "We don't have to know in advance where the scuff mark is going to be," I point out. "We just make the scuff mark wherever we make it, shift the rover over and reorient it so that we're facing along the scuff, and take the images from there."

This won't eliminate all of the uncertainty, but it'll eliminate more than enough, leaving only whatever we pick up during the last little bit of the drive. They'll instruct the cameras to take images of a position 85cm in front of the rover (this length is determined by properties of the rover and its instruments) -- wherever that happens to be -- and it'll be my responsibility to ensure that there's a scuff mark there. That won't be easy, but it also won't be excessively difficult; the post-scuff driving takes place on relatively flat ground, and we can help our chances by making a really long scuff.

They aren't immediately convinced; they normally target the same spot for pre- and post-disturbance observations. But, as a couple of them point out, the drift is likely to be compositionally uniform over its length; it won't matter if the pre- and post-disturbance observations are a few cm apart. And if they can give up that constraint, my suggestion will solve all of the rest of the problem. Chris helps by taking over the job of convincing them and working out the targeting while John Wright and I work on the drive.

There are more distractions. There are currently no IDD activities scheduled for tomorrow, but there's an MI observation in purgatory. A couple of the scientists keep pestering me for the sequence ID of the IDD sequence (which they need in order to deliver their own), but I don't want to deal with that unless the observation makes it into the final plan; otherwise it's wasted work. (Maybe I should have just given them a sequence ID; then they could have wasted their own time instead of mine, and I wouldn't have come across as uncooperative. Confusingly, this seems both right and evil at the same time.) The IDD stuff ends up not making it into the plan, so I don't have to deal with it after all.

Part of the reason the IDD stuff gets pushed out is that Jeff is planning using my original resource estimates, which included the overhead of visual odometry. Now that we've decided on relative targeting for the images, we don't need visodom any more, and we need far less time and energy than we had expected. Instead of taking an hour, we'll be done in 20 minutes, even though the drive itself is now more complicated. But it's too late to go back and change things now. I feel awful about pushing some science out of the plan, yet I'm philosophical about it: if they want us to work on a compressed schedule, this kind of thing is going to happen. Haste makes waste, or so I've heard.

I get the drive into very rough shape and hand over to John; we continue working on it together. One of the changes we make, to help ourselves out, is to broaden the scuff. We'd originally planned to step down the bedform in 10cm intervals, wiggling the wheel as we go; this would leave a scuff about the width of a single wheel. We change this to perform a small turn-in-place at 10cm intervals instead, so we'll cut a significantly broader swath out of the bedform. We've arranged the drive so that only one wheel is on the bedform while we do this, so we shouldn't slip much, and having a broader scuff means we can accommodate more uncertainty in the rover's final position. We're going to scuff the hell out of this thing. When we show the animation of the intricate drive at the walkthrough, Kevin Talley asks, "So, do the other bees know where the honey is now?"

Why are they so interested in Serpent? The dark deposit at the other end of Bonneville -- which we decided not to drive to -- contains a "mystery feature." It's a spectral signature that's not in the scientists' library, meaning there's some unknown combination of elements over there. Serpent and its neighboring bedforms were likely formed from that material, blown by the wind across the crater to settle here. So, effectively, we might be able to examine the far end of the crater by poking at this thing.

I end up staying so late past the end of my shift that I decide to stick around for the Command Approval Meeting. I've never been to one, and I might as well take the opportunity to do it now. While waiting, I get into a discussion of SEQGEN with Kevin Talley and Richard Kornfeld, who are terribly frustrated with it. So is Celina Garcia, who says she badly wants to just rewrite it.

"I've been more frustrated with SEQGEN than you've ever been with anything in your lives," I tell them. All the same, I find myself gently defending SEQGEN. It's not meant for this kind of environment, it's meant for cruise and orbital ops, which work on a very different timescale. The fact that we can use it at all, in a way so far removed from its original intent, is remarkable. In the same way, its developers and adapters aren't used to the pace of development we've pushed them into, because of MER's own highly accelerated development schedule. We were asking them for a final adaptation in less time than they normally have to develop a prototype.

I don't bring up this point, but there's also an us-versus-them aspect to it. I see a tendency among project people to treat anyone outside the project as an enemy. (Shamefully, I'm as guilty of this as anyone; and having been the outsider in this situation myself, I should know better. I choose to construe this as evidence of the trap's perniciousness.) If you're having trouble with software developed by someone on the project, you go to them and tell them there's a problem, and since their goals are your goals, they work with you. When it's a tool developed outside the project, we feel ourselves to be under attack. It doesn't help that you have different bureaucracies to work with in the two cases, increasing the perceived separation. And it doesn't help that people outside the project legitimately have different goals: they're not just worrying about your mission, they're also worrying about Cassini, Voyager, and who knows what else.

I spend some time thinking about this problem and don't come up with any answers I like. But I'm happy I can at least see the problem from this side now.

John has an idea for the extended mission. Why doesn't he become an RP-1 and I'll become an RP-2? That way, he can go back to vanpooling (which saves him a lot of money, apparently) and I won't have to get here at 7:00 every morning. I've been thinking along the same lines, I tell him. "I'm not looking forward to going back to Earth time," I confess. "You know how enthusiastic I am about this mission, but getting here at 7:00 every morning will suck that out of me in no time."[2] I don't really want to give up being an RP-1, though, since I think I prefer it to being an RP-2. So I temporize: "I'll think about it."

I'm not there much longer before I give up on the idea of waiting for the CAM. If I do become an RP-2, I'll see plenty of them in person, and if I don't, it's not a tragic loss. So I hold the door for some unlucky soul whose badge access still hasn't been restored, and I leave.


[1] By which I mean the Sol 18 Anomaly, when we got stuck at Adirondack -- making no progress toward our official mission goals -- for what seemed like forever.

[2] Five years later, I'm still no morning person. However, I fully recognize how lucky I am that my one and only complaint about my job is that it starts earlier in the morning than my brain does, so I don't bitch too much. Don't get me wrong, I bitch. But not too much.


Spirit Sol 71

During my pre-shift time, Frank, who's trying to stay awake until the CAM, comes down to hang out and shoot the breeze a little. He's not happy with his SpaceOps paper, he tells me. He wanted to write the definitive paper on how we're using RSVP to drive the rovers, and ended up with something much less than that. "But I'll write that paper later," he shrugs.

The world of "writing papers" still seems weird to me. I got so used to working on the kind of code you wouldn't bother to write a paper about. Necessary stuff, stuff JPL couldn't do without. But, let's face it, boring stuff. It's hard to compete with writing the software we use to drive Mars rovers.

Speaking of which ... "So, what are you planning to do when the project is over?" Frank asks. I don't really know. I've planned to go back to working on the stuff I was working on before, especially since that's what I've been promising John[1]. But I don't think I'd be happy with things just going back to the way they were. Something's going to have to change. I just don't know what it is.

Frank offers to arrange work for me -- graphics stuff, if I want it. Tempting, tempting. But I have promises to keep.

And meters to go before I sleep. Against expectations, we're driving today. Off in the drive direction is a long bedform named "Serpent." Serpent is too large to drive over, so we're going around it. The plan for tomorrow is to drive to its southern tip (this takes us away from the crater rim); we'll maybe poke at it with the IDD, then head on. We might also study some nearby rocks, since there are some white rocks near Serpent and this gives us a chance to get the fucking white rock business laid to rest once and for all. (That's not my characterization; Ray actually says "fucking." He wants to drive on in the worst way. I find this impatience endearing, as does Frank, who asks him to come upstairs and light a fire under Opportunity's scientists so they can get the hell out of their crater already.)

And we might get to do other stuff to Serpent, such as dragging the wheels over it to form a makeshift trench. We're going to show this little snake who's boss!

More surprising than the news that we're driving is the news that we're not going to drive into Bonneville after all. There's just nothing interesting in there -- nothing close enough for us to reach, anyway; we'd have to go all the way to the far wall for that, and that would mean kissing the Columbia Hills goodbye. Dave Des Marais asks for a traversability analysis at some point anyway, just so we'd know whether we could have gone in if we'd wanted to. But we don't want to.

Unfortunately, I'm not the only one who was surprised that we're driving. The project management was also surprised -- or would be, if they knew. They thought yestersol that we wouldn't be driving, so they've given the downlink teams the sol off. Which means nobody's here to do the usual traversability analysis and stuff. Fortunately, though, Frank happens to stumble onto Mark Maimone, who's here even though it's his day off (now, what kind of sick weirdo would do that?), and Mark takes care of it, kicking out a downlink report, INCONS file, and traversability analysis in no time.

Which means I get to relax and go to the downlink assessment meeting. Yestersol was the most complex sol we've ever sequenced (not for the rover drivers, but for the rest of the team; the day was very heavy on remote sensing). They broke records for the largest number of observations and the greatest number of different targets examined in one sol. "This is not necessarily a good thing," Ray says in admonishing the science team to trim its appetite. One price of our newly compressed schedule is that we can't do stuff like that any more. Which probably means we shouldn't have succeeded; it only encourages them. But Ray will fix that.

The meeting itself is mostly routine, though a White Rock Mafia member gives a presentation at the end -- Mysteries of the White Rocks -- that lays out their side of the argument. Some of it is Deep Geology, which means it goes over my head, but the crux of the argument is that it all depends on why the white rocks are white. It might just be dust adhering to the rocks from atmospheric settling, or deposited on them from below (as odd as that sounds) as part of the process of exhumation. But the exciting case would be that the white stuff is intrinsic to the rock, and we're sort of seeing it sweating out -- this would be exciting because the processes that cause the white stuff to get sealed in in the first place could be water-based. This would make the white rocks a smoking gun for past water in Gusev, and that is the reason we're here.

Not everyone is convinced, but I don't stay to watch the fight; I've discovered that we don't have the terrain meshes we're going to need to plan the drive, and that's something I need to take care of sooner rather than later. I go upstairs and get MIPL to kick off the process, and get a nasty surprise when I go back downstairs. All of a sudden, my badge doesn't work in the fucking badge reader. Ten minutes earlier, it was fine, and now it's declared me persona non grata. This is particularly inconvenient because the restrooms are in the non-secured area, which means you need badge access if you want to get back in.

Unless you're as pissed off as I am. Then you do what I do: you disable the fucking lock. I first try a couple of solutions that would disable the lock only when I'm on the outside of it, but I don't get them working quickly, and I have real work to do. So I just put tape over the hole. Jesus Tap-dancing Christ.

I call Security, but they can't help me over the phone. To get this sorted out, I'll have to go by the Security Office when it opens, several hours from now. This will mean sticking around well after my shift ends. Oh, goody. I'm sure to be in a real good mood, then.

The Serpent drive turns out to be trickier than it looked initially. The terrain between us and Serpent is reasonably flat, so it would be a snap to just drive to there, but there are more constraints than that: we have to be pointed at 60 degrees for communication reasons[2], which will leave us aimed away from Serpent and thus unable to IDD it. So we have to drive to the other side, then turn around to 60 degrees and come back to it. And there's an obstacle-sized rock near the tip -- there's enough room to fit the rover through there, but we're not sure how far we're going to slip in this terrain, especially since we're heading downhill. We can't just drive over it, either; we're not sure how badly we'll slip if we try, it's too high in most spots, and the scientists don't want us to disturb the soil yet anyway.

So we pull an old trick out of our bag: drive the rover as close to the gap between Serpent's tip and the rock as we feel is safe, then autonav between Scylla and Charybdis. Every time we use autonav, we add a set of reasons the drive might fail -- but then again, we can't risk not using it. I warn Ray that there's a lot of uncertainty and list all of the reasons I can think of that the drive might fail. He shrugs and says, "Sounds like an interesting experiment." So we're good to go.

Having worked out the approach, the drive itself isn't too hard to implement, even with the IDD work they want us to do first. The IDD sequence turns out to be pretty cool, actually: we bring the APXS up in front of the left front HAZCAM to get a confirmation that its doors are closed (Opportunity's APXS doors didn't fully close recently, and they want to explore this) -- that's something we haven't done before -- then place the MI on a target near the right front wheel. What's fun about this is that the IDD turret and wrist perform beautiful, complex spins and twists as part of the motions. This reminds more than one observer of a gunslinger: Ray suggests that the rover should have had a holster.

The mood tonight is more relaxed. The place is emptier. Justin Maki suggests that people are finding the mission routine: there were plenty of people here on sol 1, and for other big events. But I think it's probably just that many of the scientists are at the Lunar and Planetary Science Conference.

Both rovers are working well, and Art says we'll keep running them forever. But Robin Fergason points out that this might not be up to us. They're talking about turning off MGS, even though it's still going strong -- and playing an important role in this mission, acting as one of our liaisons to the rovers. Why would they turn it off? Because operating it costs $8 million per year. By space exploration standards, that's nothing. Hell, we spend that much on -- well -- ice cream.[3]


Well, maybe they'll let us work on the next rover, Art says. I tell him that exploring Mars is like sex and pinball: the reward for doing it well is that you get to do it again.

[1] John Louie, my group supervisor.

[2] Our UHF antenna is theoretically omnidirectional, so it's not supposed to matter what heading we end up at. In practice, however, it's not so: the rover mast and other features on the deck act as obstructions that factor into the antenna's actual performance. For a particular comm pass -- with Odyssey at a particular location in the sky -- we'll get better results with Spirit at some headings than at others. Thisol we determined that the best heading was 60 degrees (headings are measured clockwise from due north).

[3] Just in case anyone without a sense of humor reads this: yes, that's a joke.


Spirit Sol 70

It's starting already: at least temporarily, they're moving the downlink teams to Earth time. Sigh.

I've decided to keep coming in at my regular time, even though I could be coming in 90 minutes later (like everyone else), so that I can get more work done. Sigh. But maybe this will mean I'll be able to work less on my days off. (Fat chance.)

They've taken another image of the backshell -- or whatever it is -- which have failed to fully clarify the situation. There are several Spongebob Squarepants fans on the project, who have decided that that's what it is. I guess that counts as finding life on other planets.

At the downlink assessment meeting, they have a beautiful color image of the color crater panorama on the big screens. I'm really getting spoiled by the big screens. When the project is over, I'm going to have to buy a 3200x1200 projection monitor.

Anyway, the plan from here is to work the rim. We'll be here for about 3 weeks (later they say 18-22 sols), inspecting rocks, soils, ripples, deposits, etc., as we crawl along, and that will take us to the end of the nominal mission. The extended mission will be the drive to Columbia Hills.

The guy defending this plan puts up a presentation with a picture of Opportunity's crater; there's a round of good-natured booing. But the point of showing the image is to set a context: in its crater, Opportunity found the interesting stuff (bedrock) just below the rim. We can expect something similar here -- we may, for example, not need to clamber all the way down to the bottom of the crater; exploring the rim and upper slopes may do everything we need.

At Bonneville, though, there is no evident outcrop (which everyone was hoping for). Still, there's significant value in being here. You tend to get more weathering on slopes, since they present a broad face to the wind and allow the weathered material to "escape" (by running downhill), so we'll see fresh material just beneath us. For the same reason, coatings and non-basalt rock types that don't weather as fast as basalts will also be exposed here. So even though we don't see bedrock, we should see plenty of geologically interesting stuff.

One thing we'll need to do is analyze the crater slopes. The angles we're seeing, 20-25 degrees, are on the edge of what we're able to traverse, but there's a worse problem: on those slopes, we're likely to see 100% slippage. This makes it a rover trap, where we can get in but find ourselves unable to get back out. I have the image of a sort of hungry robotic ant lion, lying patiently in wait at the bottom of Bonneville for millions of years, ready for the moment an unwary robotic explorer from another planet should wander in ....

And Ray notes the other end of it: 100% slippage would mean that we could slide all the way down, unable to brake. "I don't want to try to traverse one meter down and the next thing we see is the dunes at the bottom," he tells me. Just think how I'd feel about it!

Ray also has a more serious, and pointed, question. Suppose remote sensing shows more of the same -- more of what we've already seen here. Do we even have to go in? There's a lot of discussion about this, but I think the short answer is: no.

One other note from Ray: we're big news in Baker, CA -- population 392. Don't ask me what Ray was doing there; maybe it's because Baker is the home of the world's tallest thermometer. But he was, and he tells us that people kept coming up to him and saying, "Hey, I heard you made it to that crater!" So if we're news there, I guess we're news everywhere.

Today's sequencing is just a little IDD work; I could do it in my sleep. I'm done with it and hand off to Bob practically the minute he comes in. Once again, I leave on time. This could become a habit.