Spirit Sol 680

Our drive failed. Well, that might be too strong a word. We got through the blind portion, the initial 25m or so, but when we switched to autonav, we lowered the tilt limit (as usual), almost immediately drove over a relatively sharp little ramp, and tilt-faulted.

What makes this more annoying is that, unbeknownst to me, we had terrain meshes covering that entire area -- from an earlier sol, sol 667, when they'd driven up to that point and looked out over it. (I was on Opportunity then and missed that part of the story. When I came in, they'd driven back to examine some outcrop they'd passed by previously.) So we could easily have done a blind drive right through this area -- with a higher tilt limit, so we wouldn't have faulted.


Just to make things more awkward, there was a problem at the DSN station, and they somehow lost a bunch of data from our downlink. (The data somehow made it all the way from Mars to Spain, but couldn't quite make it the last few thousand km to California. This is like swimming the Atlantic and drowning a meter from shore.) As a result, we have very little imagery from our current position -- HAZCAMs are all we had last night, though the PCAMs showed up in the morning pass. We're still missing the creamy middle -- I mean, crucial middle -- that's ordinarily supplied by the NCAMs.

We'll be able to do a drive, but it will be mostly autonav and therefore rather short -- but, hey. We still have that imagery from sol 667! John loads up the terrain mesh, and though it shows we've accumulated significant position error, we've still got good enough data to extend the blind drive to 12m or so. That gets us to the start of the PCAM coverage, which would ordinarily mean we'd be able to extend the blind drive even further, but there's some scary-looking stuff at the start of the PCAM coverage that we don't want to blind-drive through. Oh, well.

Anyway, there's a growing sentiment for bypassing Miami in favor of Comanche, a slightly more distant target that's redder (as opposed to Miami's black, which might suggest it's just regular old basalt) and has a more unusual morphology. So we aim this drive for a spot to the right of Miami -- somewhat splitting the difference between it and Comanche. And off we go.

Just after I deliver, I check the data -- and sure enough, the NCAMs have just come down. And they show what we suspected even without them: we'd have been perfectly fine sequencing this entire drive as a blind drive, which would have more than doubled our distance. Too late to change it now. Double-foo.

While I've been covering Ashitey's shifts on this side of the planet, he's been on the other side of the planet, investigating Opportunity's IDD anomaly. And the news isn't good, or at least, that's what Frank tells me. They haven't done anything with Opportunity's IDD since the fault, but they've been busy in the testbed, and their testing there has tended to disconfirm the hypothesis that the IDD is simply temporarily having trouble getting off its hook. Rather, it's looking more and more like a real actuator problem, a hardware problem we won't be able to solve and may not be able to work around.

I'll be back on Opportunity tomorrow morning, starting with an early meeting to explore the results of the tiny move they'll send up tonight. And then we'll know more.

[Next post: sol 682 (Opportunity sol 660), December 3.]

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