We don't have much to do today, just a tool change from APXS to MB, and Ashitey and I decide to make Terry (shadowing us today) do it. So we have even less to do.
But we do have a Spirit Drive Meeting to go to. Our goal is to figure out what we can, and should, do about driving during the winter.
It very rapidly starts to look like the answer is: nothing. We need to gain 5-6 degrees of tilt in order to get a 15W-h power increase. It's doubtful we could do that, and anyway we think we don't need to: the current 10.7-degree tilt is believed to be survivable, though not with much room to spare.
Unfortunately, the current IDD work volume is "not very exciting," as Squyres laments. There are layered rocks and vesicular basalt nearby, either of which would be better -- indeed, we could reach the layered stuff just by turning clockwise, something we definitely can do. And it's appealing on other levels: we'd be facing south, with the solar panels aimed north, which is gives us less shadowing, is better for science, and improves our HGA comm. The problem is that our UHF comm will be poor, and since we relay heavily on that -- even more during the power-poor winter months -- that consideration will probably trump all the others.
The rules we decide to adopt are that any drive must:
- Be in the best interest of survival.
- Improve comm for the winter.
- Improve our solar tilt.
- Improve science.
- Include a contingency plan to return to safety in case the drive doesn't work out.
We might be willing to relax these constraints, but they're pretty discouraging when you look at them. There are a lot of ways to make things worse, and not many ways to make them better. So we're likely just to sit here, take lots of pretty pictures, and do a little IDD work. And wait for spring.
At least Spirit's IDD is working in the meantime. I'd forgotten about this until Ashley reminds me, but one of the possible explanations for our poor rover's lame wheel was that some circuitry had failed on board -- and it so happens that one of the possible failures was one that would have taken the IDD with it.
See what I mean? There are lots of ways things could be worse.
[Next post: sol 817, April 21.]