Opportunity Sol 381 (Spirit Sol 401)

Thisol we're completing our IDD work on Russet, after which we drive to the Alvin and Jason craters.

The drive to Alvin and Jason is my first time planning a drive using orbital imagery. We don't have good enough NCAM or PCAM imagery to reliably drive as close to the craters as we want, so at Jeff's suggestion, Brian and I go downstairs to work with Tim Parker to plan the drive. He's basically got an imaging program with the rover localized to a point in an orbital picture, and he can draw lines of various lengths and at different angles. He's clearly been getting a lot of practice: with his help, it takes just a few minutes to work out the drive.[1]

Sadly, the science team has decided they want to drive between the craters after all (not skirting them by driving south of Jason, as I'd suggested a few sols ago). On closer inspection of the imagery we do have, the crater my plan would have avoided turns out to be the more interesting one, as it appears to contain outcrop material. But that's OK, this isn't our big drive sol.

Our big drive sol comes next. Or, more accurately, our series of big drive sols. We're going to head south in a big way, continuing to Vostok by way of a cluster of three craters more than 300m south of us. Though I doubt this is possible, I'm hoping to make it there in two sols, which would almost certainly mean breaking the distance record once more (however briefly, before it's broken again). For the record -- no pun intended -- the current single-sol drive-distance record is 156.55m. I'll have a few chances to break it. Even if I don't succeed, it'll be fun to try.

[1] A much-refined version of this approach has become the norm for Opportunity's long drives across Meridiani Planum -- as we're doing now to make our way to Endeavour, for instance. Tim Parker and Matt Golombek lay out a large-scale traverse path, and the RPs make tactical decisions about how closely to follow it, based on what we actually see from the surface each sol.


g said...

How did the orbital imagery drive figure the rover's pointing orientation with respect to the imagery? Did you match features in the orbital and rover images, or does the rover have an on-board compass that is close enough?

Scott Maxwell said...

@g For position, we match up the local images with the orbital images. For heading, Spirit and Opportunity have something called an "IMU" -- an Inertial Measurement Unit -- that performs the job of a compass. The IMU tracks pitch and roll as well as yaw (heading).

Incidentally, the sort of magnet-based compass you might use on Earth won't work on Mars because Mars has essentially no magnetic field; our "compass" uses gyros to track heading (and pitch and roll) instead.