The rover got a little confused. The last 12m of the drive were supposed to be handled by autonav, because it involved traversing a region we couldn't see well enough to plan the drive ourselves. It turns out the region contains a hollow, which spooked the autonav. So the rover drove about 12m, but only progressed 5m towards the goal before stumbling onto the hollow; the remaining 7m was spent shuffling back and forth, trying to find a safe path out. As it happens, the rover found a safe path just at the end -- but too late; the time-of-day limit hit.
Well, I warned them yestersol that something like this might happen. But I'm still kind of bummed. As it happens, the scientists are happy anyway: the rover's back-and-forthing dug a shallow hole in the loose soil of the hollow -- "spontaneous trenching," someone calls it. Picking up on the theme, the deep tracks we just created are dubbed "Serendipity Trench" and becomes the focus of science observations. Sow's ear, silk purse.
The big news is that, even before we reached the hollow, we met mission success: our odometry now stands at 313m, comfortably exceeding the 300m NASA required us to achieve. All we have to do now is not break the rover before sol 90, which I think we can handle. Since Opportunity has just been shuffling around inside its crater, its total so far is only about 55m, so we might end up driving extra to make up the difference (the two rovers combined are supposed to reach 600m). Well, if they insist.
I'm still feeling bad that the drive didn't reach its goal, but the downlink assessment meeting makes me feel better. The scientists are happy with Serendipity Trench, and they're even happier about the odometry total. They announce the new total (now revised upward to 314m), and there was much rejoicing.
Matt Golombek is the SOWG chair again, and he states bluntly that we'll be driving. "I'm here for three sols and I want to be at the rim before I'm off." There's little, if any, opposition to this goal, but some of them underestimate Matt's eagerness. In discussing the long-term plan, a scientist says offhandedly that the rim is about two 15m drives away, and Matt quickly corrects him: "One 30m drive, thanks!"
Where exactly on the rim do we want to be? Ahead of us and a little to the right, on the very lip of the crater, we can see two largish rocks that might be very interesting science targets. One of them appears to be black (though this may just be shadowing), and is jokingly dubbed "Darth Vader." So the other, lighter-colored rock is tentatively named "Luke Skywalker." The plan tomorrow is to drive Spirit up to the rim between Darth and Luke, which are easily far enough apart for this. On subsequent sols, we'll look into the crater from that position, do remote sensing on both rocks, and then probably pick one of them for more focused study.
Since I'm shadowing today, I get to slack off. (What this actually means: I do other work, not rover-driving work.) I also get to attend the end-of-sol science discussion, which today is about the rim traverse plan. We'll reach the crater rim at its southwest edge and traverse the southern rim from the southwest area to the southeast or east. We won't go all the way around (this would be about 750m), as our next destination is the Columbia Hills to the east. When we reach the eastern edge of the crater, we'll literally head for the hills.
But will we enter the crater first? There's a lot of support for this, but we won't know whether we can do it until we reach the rim: if it's too steep, or the sand is too lose -- or there's just nothing of interest -- we'll skip it. We should know in a sol or two.
Courtesy NASA/JPL-Caltech. Final front HAZCAM image showing Serendipity Trench, the terrain we disturbed by our back-and-forth "roverdancing" at the end of the drive.