Spirit Sol 687

Second time was the charm. "As usual, a perfect drive!" exclaims the SOWG chair. "As usual," John mutters sardonically, "not as always."

Well, be that as it may. They have indeed revised the drive metric, making us a whopping 100m behind schedule. So we're driving.

Ha, ha! Only kidding. Of course we're not driving! Instead, we're spending the next couple of sols IDDing the patch of outcrop this drive took us to. And, of course, imaging nearby rocks and such. The outcrop is named Algonquin, and the target names have been selected from a list of tongue-twisting Indian names. After listening to the team stumbling over the names in the SOWG room, I thumb the mike and say, "I just wanted to remind everybody that the reason we name features is to make them easier to refer to." This wins laughter and applause. The SOWG chair proposes that our next target namespace be limited to three-letter names.

The IDD sequencing is our usual abbreviated campaign: on the first sol, an MI mosaic followed by an APXS placement; on the second, a RAT brush followed by a repeat of the MI mosaic and APXS placement. John has this well in hand -- true to form, he mostly copies and pastes from a previous campaign -- which leaves me time to look ahead to Friday's drive.

Which doesn't look pretty. About 15m away is a ridge, beyond which we can see terrain, but we have no range data on it -- that is, we have no idea how far away it is. PCAMs usually can give us range data out to 100m or so, so the fact that we're getting nothing suggests that what we see is at least that much farther away. So our strategy must be to drive to the ridge, then switch on autonav and hope for the best beyond that.

If we can even get to the ridge. The terrain here is just rugged enough to make that really, really difficult -- every apparent solution is thwarted by some rock or other.

Moreover, the target beyond, a big red mound called Comanche, is part of the stuff we have no range data for. So we don't know how far away it is, and thus we don't know how long it'll take us to drive there.

Because Monday's such a tight sol, we don't want to plan a drive that sol. Instead, we'll take the unusual step of planning two drives Friday. The first will take us to the ridge, then autonav past it. The second will be an all-autonav drive. Since we're fairly sure Comanche is more than 100m away, and the two drives combined aren't likely to make that much distance, we can just pick a point ~ 100m away and have both drives aim for it.

We've never done this on Spirit, but it's similar to what we did on Opportunity over President's Day weekend, so we're confident it'll work. We end up scrapping the idea, though, less for technical than for staffing reasons. Next week, John will be absent because of his fiancee Helen's surgery, Ashitey is still tied up with debugging Opportunity's IDD, and Chris Leger is focused on the FSW release. This leaves me as the only usual Spirit RP, and I have an unavoidable doctor's appointment Tuesday, a follow-up with my surgeon.

As a result, Sharon's had to schedule two Opportunity RPs, Frank and Jeng, for Tuesday. And we really don't want to make them drive. They're both good RPs, and everything would probably go fine, but the combination of a tight uplink, two RPs somewhat unfamiliar with Spirit, and unknown and likely hazardous terrain makes us nervous enough to call it off.

Instead, Friday we'll plan just one drive, and Monday we'll look at the data from that drive and plan the next one. We won't send that sequence Monday, though -- Monday's schedule is just too tight for that -- we'll hang onto it and have Frank and Jeng send it Tuesday.

This means I get to work on the rovers Monday, instead of spending Monday pushing on the RSVP software release for Phoenix. I can't say I'm disappointed.

[Next post: sol 690, December 11.]

No comments: