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.


Anonymous said...

This is easily one of my favorite posts so far. Disabling security to get real work done, spending more on ice cream than on Mars Global Surveyor, and a new word to me--Thisol.

Thank you Scott!

Scott Maxwell said...

Thanks, I'm really glad you liked it!

But the ice-cream cost thing was a joke -- honest! We ate a lot of ice cream, but not that much. :-)