2009-03-31

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.

3 comments:

Tor Hershman said...

Ain't Earth a pit?

I mean - our father who art pond scum hallowed it be thy fartin' of oxygen.

ermanno said...

I'm curious. You're always talking about this 3D mesh. Can you show me/us how it looks like?
Thanks.

Scott Maxwell said...

@ermanno Sure! You can see one here. That gray landscape surrounding the rover model is the terrain mesh.

As it happens, this is one of the images for which I helped write a caption way back on sol 11.