Opportunity Sol 1019 (Spirit Sol 1039)

Yestersol's Opportunity drive went well, so we're not going anywhere in particular today. Mostly, we're going to sit and take pictures.

But we are doing a bit of driving. In order to optimize our downlink for the weekend, we're just going to do a comm turn.

Steve Squyres raises an interesting issue with this. Back when we developed our strategies for driving with this IDD problem, one of the things we told NASA HQ was that we'd hover-stow (a.k.a. "thinker-stow") whenever possible, mostly to minimize the risk that the IDD would fail in the stowed configuration. However, we've kind of lost sight of that, preferring to do a full stow on every drive, because it's so much easier.

It is also, in more than one respect, safer. In order to drive in the thinker-stow position, we need to ensure that we don't drive any wheel over anything bigger than 3cm. Also, we can lose calibration when we do that, because the IDD bounces around more than when it's tucked safely below the rover's chest.

What ends up putting the kibosh on thinker-stowing for the day is not any of those considerations, but one more esoteric. The rover won't drive when it thinks the IDD is not stowed, and the thinker-stow position doesn't meet the rover's definition of a stow. So you have to poke a flag that tells it to consider the IDD stowed anyway. However, the command that does that hasn't been tested under the new flight software, and the potential downsides are significant. So we don't do it. I'll have to look into the matter soon and ensure that we can thinker-stow in the new FSW, but at least for today, things stay simple.

[Next post: sol 1053 (Opportunity sol 1032), December 19.]


zhdoroga said...

Thanks so very much. Just found your blog (link from Stu to Scott to you). It's fantastic you kept a diary (if only to appease your spouse!). I've followed the lives of the MERs since their inception and I'm thankful for all the effort and dreams, ambitions, work and sacrifice that went into their success. Your writing let's me touch the missions in a unique, and not to be lost, way. Thank you for all your effort, the work and the presence to publish these recollections.

Scott Maxwell said...

You're very welcome! It's a real joy to be able to share the adventure with fellow MER fans such as yourself!