Spirit Sol 155

Lately the meeting schedule has been running early, so I've been coming in early. Today they're holding the meetings on time, which means I'm a lot earlier than I need to be.

This gives me time to help out Larry Soderblom and a couple of the other scientists, who want to know how to use the fancy 3-D shuttered LCD goggles to view 3-D images in SAP.

"You can't," I tell them. "They only work with RSVP. Want me to show you?"

They do, so I do. I set them up to use a (ahem) preview copy of the next release, which has extra features that make this a little easier. We load up some NAVCAM images they want to see, and I show them how to switch the system into true 3-D mode. One of them takes careful notes so that he can tell everyone else how to do it, then repeats the whole thing from scratch while I watch. He gets it exactly right the first time. What a good teacher I am!

The start of thisol's drive has an odd feature, a California U-turn. (Chris likes the term so much, we name the sequence after it.) This is a short drive forward, a 180-degree turn-in-place, a short drive backward, then another 180-degree turn so we're facing forward again. After that, we drive on normally.

This odd little dance is at mechanical engineer Chris Voorhees's request. It's to help us gather some engineering data on the right front wheel, which has started drawing more current recently. We're not sure why it's doing this, but it's not good news. At the rate it's going, it will start to be a problem by the end of August, so we're starting to think about what to do about it now. I talk with Voorhees about how we'll cope with it. Driving backward is one solution, since it works better to drag a dead wheel along than to try to push it ahead of us. He also says we can feed the wheel as much power as possible, so that the mechanical system offers as little resistance as possible to its turning. This makes the wheel a little less dead ("only mostly dead"), if you see what I mean, which might help.

"I realized the other day that I'm predestined to have a failure review," he sighs. With the rover at less than twice its designed age, most components of the rover have experienced less than twice their design limits -- the cameras have taken fewer than twice the expected number of pictures, the IDD has been used less than twice as much as planned, the mechanical system as a whole has experienced fewer than twice the expected thermal cycles, and so on. But the mobility subsystem, Voorhees's baby, has already been used for something like five times its design limit. We were only supposed to drive the thing 600m, and we're already over 3000m. No wonder the wheels are falling off.

In the spirit (ha) of always-look-on-the-bright-side-of-life, I point out that he'll have a lot to be proud of in that failure review. We're passing five times the design limit and still going strong. He agrees, but he doesn't look any less worried.

Since I got picked to be a rover driver, I've been more careful than usual when driving in real life. This is because I don't want to hear any lame jokes about being able to drive on Mars but not on Earth, and suchlike. I've avoided any problems, but Chris Leger didn't -- he just got a speeding ticket. John Wright got one, too, not long ago.

I drive home very, very carefully.