I wasn't on shift yestersol, Paolo and Matt were, but they called in me and Jeng to give them some advice on driving in an area where we lacked good imaging. Our advice was to suck it up and use autonav. They did, reluctantly -- but it turned out that autonav got us within about 50cm of where we wanted to go, plenty close enough, and we're ready for more.
(Incidentally, when was the first time we had two RPs on shift neither of whom was from the original set? (I tend to think of Jeng and Ashitey as originals, though strictly speaking they weren't.) It wasn't yesterday, surely, but I don't know when it was. Ah, I'm such an old-timer now.)
But we're not going to charge down the trench, going for distance. Instead, we're going to try to address a question that the scientists have been kicking around for a while: what causes the banding we're seeing on these ripples? It looks as though there are several sets of ripples, one atop another, with slightly different albedos -- and what would cause that?
To try to find out, we're going to drive up on one and plant the MI on it. That's a slightly scary and just plain odd thing to do; we normally try to avoid these ripples, not climb them. But it's all for science, you know. So it's game on.
I'm RP-1, and Matt's shadowing me today. Since he's come up to speed on the driving (so to speak) impressively fast, I decide to hand him the reins and see how he does as RP-1. The short version is that he does great, planning a very nice approach where we scoot about 17m down the trench, then turn and charge right up onto the ripple. There's a bit of concern about whether we're going to hit the ripple in our post-drive IDD deploy, but then we realize that the ripple's only about 21cm tall, so the IDD would stay completely above it even if we were buried up to our wheels in the thing.
To make things more complex, though, we have very strict limits on our comm headings. If we're about 3 degrees off one way, we'll get a paltry 23 kilobits -- that's kilobits -- and if we're about 3 degrees off the other way, we'll be at a heading where the PMA will prevent us from talking to Earth at all, so we'll get nothing. Fortunately, ripples are broad, and we should be able to hit it spot on.
Though outwardly cool, Matt confesses he's not completely confident -- "I'm not gonna sleep tonight," as he puts it -- and while that's a feeling I know well, I have a lot of optimism about this drive. As long as we don't end up stuck in the ripple, and we've taken good precautions against that, it should be like hitting the broad side of a barn.
Should be. At least, that's what I'll tell myself when I'm trying to sleep tonight.
It's not until we've wrapped up for the sol, and I'm back in the office talking to someone, that I realize we overlooked something important. I literally run back upstairs to the Opportunity sequencing room, hoping other people will still be there.
Luckily for me, there are several people who haven't left yet, so there's someone to tell. "We just planned sol 810!" I exclaim. "That's nine times the nominal mission! How did we miss that?"