Spirit Sol 509

It's a tight sol, with the uplink due in just a few hours, so we're starting at the ungodly hour of 07:00. I'm also working with John Wright (he's RP-1 and I'm RP-2), and who the heck knows when was the last time that happened.

All that really happened while I was gone was some IDD work on the magnets and solar panels, followed by a drive to Backstay, a pointy, very roughly tetrahedral rock just a few meters away from the end of our last drive. Thisol we're starting an IDD campaign on Backstay, which campaign might or might not include using the RAT.

The one good thing about tight sols is that they're usually relatively simple. Then again, this is because our time is relatively limited, so it doesn't make things that much easier, really. And the uncertainty about the RAT adds some complexity.

The problem is that the question of whether we can safely use Spirit's RAT still hasn't been resolved. Or anyway, not everyone thinks it has, which comes to pretty much the same thing. Alistair, the RAT PUL, says at the SOWG meeting that he got a thumbs-up from Eric Baumgartner, but nobody else seems to have seen the email. Later on, the email shows up, but it seems Eric's approval was based on a false premise -- he thought a test had been run that in fact hadn't. So Ashitey's back in the testbed all day, working feverishly against our tight schedule to get the right test run before we have to uplink.

To cope with this uncertainty, John and I put the RAT-related commands in a separate sequence and work out a way for the backbone sequence to run correctly whether the moves in the RAT subsequence are performed or not. That way we can cleanly drop all the RAT stuff just by not delivering that sequence. The cost is that we have to simulate both cases carefully, more or less doubling our validation work, but we'd pretty much have to do that anyhow; this is the cleanest way.

And then it turns out we might not be able to use the RAT on this target after all: the PUL selected a target using the reachability map, but the reachability map doesn't know that we've restricted the allowed range of motion for the turret joint. And it turns out that the target the PUL selected, which is in a fairly narrow reachability band, causes us to violate that limit. Later he finds another target, though, one that's reachable and satisfies the science needs, so we're back on.

Except that we still haven't heard from Ashitey. Time passes. In the end, we get the go. Backstay is in for a brushing.

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