Spirit Sol 626

This morning brings good news and bad news. The good news is, we made it. This is truly spectacular and receives its due of praise from all concerned: it was one of the most difficult approaches we've ever done, and we nailed it.

The bad news is, it's not safe to IDD. At the end of the drive, we carefully wiggled the wheels, and the data and images show that the vehicle moved during the wiggle. This implies that it might well be unsafe to deploy the IDD. So we won't be able to start IDDing thisol; we're going to have to spend the sol figuring out how to either settle the rover a bit better or bumping to a new position. (We also displaced a rock we drove over on the way in, tilting it up such that there was probably only 2-3cm clearance between it and the bottom of the WEB. Oops.)

The basic decision is: wiggle only, or drive and then wiggle? Ashitey wants to drive first, but I eventually talk him out of it. In this area, treacherous as it is, driving is merely a way of trading the devil we know for the devil we don't. We don't have any good way to raise the odds that we'll be stable at the end of the next little bump, so we might as well try to make Spirit more stable right here.

This argument would probably have been a loser, given that thisol is absolutely our last margin sol -- we can't just try for stability thisol, then drive and try again nextersol if this doesn't work, because we're going to be on travel then. (Or, to put it another way, we could drive nextersol, but there's not much point because nobody will be around to develop the IDD sequences that are the real point of this endeavor.)

But Squyres declares that Hillary is such a high-priority science target that they're willing to wait. If we simply can't get the IDD into position before leaving town, they'll wait until RPs start returning to town Wednesday. That means we have sols to spare, so we can try one thing thisol and something else nextersol if it doesn't work. That's the least risky approach, so we go with that.

The settling tactic itself is a fairly straightforward one. We wiggle each wheel, one at a time, taking plenty of documentation images and visodom updates as we do. Then we cock each wheel to the left, so that the paddles are transverse to the direction of slip. If all goes well, we'll come in tomorrow and see a tiny amount of slip on the first wiggle and no slip after that, and we'll be stable and ready to deploy the IDD. If not, well ... the scientists will have a lander for a few days.

"Alternatively," Steve says, "if this doesn't work, we could give up and drive to another rock. There are other rocks around here -- much less interesting from a science perspective, but they'd probably tell us what we need to know. It's the RPs' call."

"I'm not going to want to give up, Steve," I tell him. "I'm still pissed off about Burns Cliff."

And I am, too.

Courtesy NASA/JPL-Caltech. Some days I rock. Other days I rock hard. This was one of the second kind.

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