Opportunity Sol 580 (Spirit Sol 599)

Thisol's drive shapes up to be rather dull. We didn't get drive-direction PCAMs for some reason, so we're limited to the NCAM mesh, and this limits our drive to 15m or less.

But, of course, it's never quite that simple. Thisol there are two complications. First is the comm heading. We end this drive by heading south along a trench to a point where we hope we'll be able to cross a ripple on the next sol. Because of this southerly trajectory, the most natural heading after this drive would be about 200deg. But this is a terrible direction for comm. Good would be about 310deg.

On Spirit -- no problem. Turn in place. But on Opportunity, turns-in-place are limited. Paolo checks out an alternative drive, where we do a sort of K-turn before heading backward down the trench, but this doesn't cut down the turn's magnitude enough to be worth the extra effort and uncertainty -- not to mention that it converts the turn to a counterclockwise one, which is even less desirable.

After wrestling with this problem for a while, I realize we've overlooked something. The turning rules are relaxed when we're on outcrop -- and at the end of this drive, we'll indeed be on outcrop. So we should be able to do the large comm turn after all.

If we're sure we're going to be on outcrop, that is. We can solve that problem by using visodom -- but we don't have time to use it the whole way. In the end we use visodom for the first half of the drive, then do a blind segment with a visodom-based slip check, and then go the final segment blind. There's a little bit of finger-crossing involved in this, but not too much. If the slip check passes, we're making real progress, almost certainly enough to make it where we think we're going. And if we get it wrong, well, the turn in place is clockwise, so at worst, we should just be piling up dirt on the outside of the turn -- not scooping it into the wheel, which is what happens if we turn the other direction. And if we're really bogged down, one of the timeouts on the turn segments should trigger and keep the problem from getting too bad.

I think I'll cross my fingers anyway.