Spirit Sol 185

Yestersol they saw a weird, sudden temperature decline at about 13:30 LST, as reported by the temperature sensor covering the right front wheel. Scott Doudrick wonders aloud whether it might be a shadowing issue, so I use RSVP to project the shadows on the rover at that time of day. It's not a shadowing issue. Later we hear that this is something that happens a lot, and nobody knows why. I stare at the graph for a while, trying to think of a plausible explanation, but I come up empty.

Thisol is basically similar to yestersol, continuing the testing. Afterward we're supposed to drive to a new location, but this ends up being cut because we can't afford the resource usage. So it turns out to be a fairly light day for us.

The good news is that the testing might be working -- that is, not only are we learning what we wanted to learn, but the experiment to reflow the wheel lubricant might actually be doing that. Daniel Limonadi says that they've already plotted the data, and it's showing the right front wheel's current draw more "in family" with the other wheels.

Daniel mostly works on Opportunity, where he's trying to persuade the science team to take better advantage of Opportunity's temporary power-rich situation. Opportunity's parked on a slope where her solar panels are aimed right at the sun -- even with Opportunity's stuck-open heater (which is being mitigated by their nightly Deep Sleep) they're getting so much energy they have to shunt, wasting some of it. When they leave this crater, that won't be the case any more, and Daniel dreads hearing the scientists start complaining about a lack of energy again. "They should use it while they've got it," he says.

Doudrick commiserates: "I dream of the days when we used to say, 'Here's a huge energy spike, let's put a comm pass here.'" We're farther from the equator than Opportunity and not particularly aimed at the sun, making us the power-poor mission for the time being.

The wheel-current news from Daniel is almost too good to be true, so I go ask Lori Shirashi, one of the Mechanical folks, for more details. She shows me plots of the current draw from the recent test. The right front wheel is higher than the others -- "but much better than it has been," she assures me. In fact, she says -- pointing to a different plot -- the problem might have been slowly getting better on its own since about sol 150.

The current working theory is that the problem was caused by our long drives. Driving pushes lubricant out of the gear box, and since we were driving during the warmest part of the day, the lubricant was too cold to flow back in at night. We're been sitting relatively still since about sol 150, giving the lubricant a chance to flow back in during the warmer parts of the day. Yestersol's "Martian Jiffy Lube" seems to have just helped the process along some.

So maybe, just this once, being in denial was an OK strategy.

[Next post: sol 190, July 16.]