Spirit Sol 49

The rover's batteries are fully charged, but mine aren't. I'm not sleeping enough. So it's particularly nice that I get to see a lunchtime science talk -- it was delayed for some reason today. Nathalie Cabrol tells us about the implications of the features we see in our trench, and why we've stopped here for a while instead of driving on (which she's comically apologetic about). For one thing, the hollow we've stopped by is the last one we can see between here and Bonneville, so if we're going to investigate those features, we'll have to do it now. As Dave Des Marais told me yestersol, the polygonal soil structures are another reason to explore here -- they're like the ones you see in parched desert soil, cracks caused when water and salts evaporate out of the soil, fracturing it. She's careful to emphasize that there are multiple possible explanations, but she's clearly excited about what she sees here. She's looking forward to the results of the MI images we'll be getting today as we continue exploring the trench. (Incidentally, Art Thompson, ever the instigator, remarked in yestersol's downlink report that Spirit's trench was "the best Martian trench ever." Of course, there's only been one other, and you know who dug that one ....)

After the talk, Frank asks me to look into a SEQGEN-related problem. It turns out to be yet another instance of the ridiculous comment problem. There are a couple of spacecraft commands which, if you add comment text to them in your sequence, trigger a SEQGEN bug. For some reason, this bug has multiple symptoms; I can't tell why you sometimes get one set of symptoms and sometimes another. Frank already knows about this problem and tried to remove all of the problematic comments, but he accidentally left a single space character behind on one of the commands, and that was enough to trigger the bug.


At least yestersol seems to have gone well -- as far as we can tell. The IDD is in the middle of a long MB integration, which is exactly where it should be at this point. A few hours hence, it will switch tools, stopping the MB and replacing it with the APXS, but this hasn't happened yet. We get some MI images from yesterday -- only one full-frame image so far, but it's a beautiful shot anyway.

Other images we got back, as it turns out later at the downlink assessment meeting, appear to be out of focus, but that's why we take a series of them. When you look at something underneath a microscope, you always have to turn the focus knob until whatever you're looking at is in focus. We clearly can't do that focusing interactively when the microscope is on Mars, with 20 minutes between when you turn the knob and when you see the result, so we take a different approach: we figure out in advance where the best-focus position is, and we take several images around that position -- some a little closer, some a little farther away, to compensate for positioning uncertainty. The images from the middle of a couple of yestersol's series are out of focus, but they expect that when we get back the outer images, they'll be focused.

And we'll be doing that again tomorrow. Oh, will we ever. Yestersol we did three MI series, a total of 21 images, and tomorrow we're doing 22 images. (This total of 43 images, incidentally, is a large number but is short of the 47 MI images Opportunity took of its trench. "We have to beat you at something," Frank says.) Plus, on both sols, we're using the MB and APXS as well. It's amazing that I've come to consider this an easy sol: at the start of the mission, I'd have been severely worried about this. Now it's almost a no-brainer. (Not that I'm complaining: with the sols we've been having lately, a couple of no-brainers are just what the doctor ordered.) Next sol, we drive again.

LTP reports that mission success is basically unchanged, but I learn something from the report: mission success is 600m of driving distance, not 1km as I had thought. Which means we're about a quarter of the way there.

There are a couple of very short science talks. I'm distracted, so I extract exactly one piece of information from the pair of talks: the darker side of the drifts are less dusty than the lighter side and display a weak olivine signature. Maybe that's two pieces of information.

After that I help the scientists plan tomorrow's MI targeting. They're trying to come up with names for targets that lie at the bottom of the reachable zone, a line that divides the part of the trench wall we can't reach from the part we can. They name one of the features DividingLine, which is painfully generic but they're in a hurry. They need one more name, and they take my suggestion: MasonDixon.

W00t! I named something on Mars!

The SOWG meeting goes surprisingly smoothly and is over in no time. Afterward, more than one person remarks that it was "the fastest SOWG ever." I attribute this to the fact that, at least in broad outlines, we're copying Opportunity here, and Ray Arvidson is determined that we shall do so. So there's not much argument; they can skip almost immediately to figuring out how much of their plan fits into the available resources. Most of it, it turns out.

As I did yesterday, I go ahead and start sequencing in this meeting. That's a lot easier on the rare sols like this one, when there's not much debate about what they're going to do, and they don't need me to help them much. I don't get far, but I don't need to, this being such a piece of cake. I'm done sequencing by the time Bob shows up, with only one IDD move I don't like -- at one point, the APXS comes uncomfortably close to scraping the material we dug out of the trench. Fixing this will give him something to do, so we hand off in record time -- earlier than ever, before the activity plan approval meeting even starts.

This leaves me with a little bit of time to gossip and chat. Bob Kanefsky voices a common lament, namely, that he never knows whether to say "Good morning" or "good night," and suggests "good sol" as a Martian replacement. The juiciest rumor is that the NASA Inspector General is coming. Apparently -- we have this on very good authority -- a bunch of Shuttle guys came out to learn about our flight ops approach, decided that our way should be the model for doing ops, and wrote a glowing report that they sent out to the directors of all of the NASA centers. (It says something that everyone who hears the story to this point is cringing in embarrassment, hiding their faces in their hands, and so on, but the story doesn't end there.) Apparently, the IG's office decided that we can't really be doing that well, and hence that we're probably doing something unlawful, and they've opened (or "are opening," which might mean it will never come to pass) an investigation. I can't fathom what they think we could possibly be doing wrong, or for that matter why NASA would be so suspicious of success. (That says a lot, too.)

Really, the project isn't doing anything wrong. Except for feeding us all that meth. It's hidden in the ice cream.

I also have time to deal with more SEQGEN problems, which is good because we have more. The server needs to be rebooted again (though, to be fair, this may not be a SEQGEN problem, it just shows up there), and apparently this also happened yesterday.

And I push forward on another front. One of the daily time sinks we kept dealing with was going through our sequence flow structure with the TULs and SIEs -- showing them which sequences we had, and which other sequences we call from our sequences. This has to get done, because the rover drivers' sequences often incorporate a large part of the day's plan. But it takes time and is distracting. So a few days ago I wrote a script to make the list for us, and today it occurs to me that I can just show the TULs and SIEs how to run the script for themselves. Today I show Kevin Talley, who's enthusiastic about it. Teach a man to fish, and you don't have to deal with him any more, that's my motto.

It's time for me to leave, and on my way out I remember about the midnightly science lecture, so I go back and wait around for that, reading Nicholas Nickleby on the Web while I wait. The science talk is again given by Larry Soderblom, who discusses El Capitan (the rock Opportunity has driven to; Larry shows us a beautiful 3-D mesh of it) and the Marsberry phenomenon. Larry says that the Marsberries, or blueberries, actually look more like Cocoa Puffs, and later he uses an analogy with a "thin candy shell." Seriously, he must be hungry.

Anyway, the prevailing theory is that the Marsberries aren't deposited on the surface (say, by rain nucleating around airborne volcanic ash -- think of prehistoric volcanic hailstones that became rock), they're formed in place somehow. There aren't many processes that would explain this that don't involve water, but then again there are questions about why we see olivine at all, when olivine is so readily eroded by water. I actually think of what I think is a good question and ask it: what exactly does olivine turn into in the presence of water, and whatever that is, do we see a lot of it around us? That might tell us whether there was water and it just didn't get around to eliminating all of the olivine, or whether something non-water-related happened instead. Larry looks surprised and says that's a good question and he'll look into it. Impressing Larry is not easy, so I feel absurdly proud of myself.

The Marsberries are also thought to be spread throughout the terrain (and within it, as we know from finding some in Opportunity's trench). As the wind erodes the surface, the Marsberries are left behind. I think about that for a second and ask another question. If that's true, I say, the Marsberries should be thicker on the surface than under it, since the surface Marsberries represent everything that used to be above the current level. (One other implication occurs to me now: you could use the same observation to figure out how much more volume there used to be above the present surface level, assuming Marsberries form, or are deposited, at a constant rate.) That's right, according to Larry, and it's one of the things they're going to be looking for as they continue exploring the crater.

Ah, this science thing isn't so hard after all.

This last bit doesn't fit anywhere, narratively speaking, but it's cool: Randy Lindemann knows all kinds of crazy stuff the rover can do. He describes using the rover to flip over a rock. You drive it over the rock so that the rock is between the two back wheels on one side. Then you drive all of the wheels backward except for that middle wheel, and as the middle wheel drags backward, its cleats catch the underside of the rock and flip it. If little Martian bugs crawl out, you win unlimited funding.


Anonymous said...

"Spirit's trench was "the best Martian trench ever." Of course, there's only been one other, and you know who dug that one ...."

Viking, right?

Scott Maxwell said...

@Anonymous D'oh! At the time, I was thinking of the same trench as Art meant, the one dug by Opportunity. But I guess you're right: Viking beat us to it.