It's autumn in Gusev Crater, and the sun is moving lower in the sky. Opportunity is near the equator and doesn't see much of a change, but Spirit is feeling the chill in the air. The power we are getting from the solar panels is steadily decreasing - not enough to make a difference to our science activities now, but enough that we can see when we're going to have to start worrying about it. Last winter, the clever team got Spirit onto north-facing slopes to tilt the solar panels toward the low sun. This autumn, we are moving off Husband hill on a south-facing slope and into a basin, so there's some urgency we feel in getting into a position to be on north-facing slopes come winter.
Fortunately, because the year on Mars is twice as long as on Earth, it's not winter yet (though in Santa Fe, temperatures have been in the single digits F and there's been snow!). So, we have a couple of months yet before winter really sets in. But a couple of months to the rover is not so long when it takes a whole day to drive 30m! Just as I came on as a new science team member, one of the first telecons I attended addressed this issue. It was decided that we needed some serious discipline to get us where we needed to go, into the basin, with some margin, so that we could find safe haven for the winter months. To me, this was a huge blow - bring new, excited team members on to the rovers and then tell them you're going to have to rein in a lot of your scientific curiosity?!? But that's the reality of the situation if we want to keep these amazing little machines in good health for future discoveries.
This issue came up again this week, as we saw a spectacular outcrop and half the team wanted to go there to see what it is and half the team wanted to press on to make sure we get to safer ground. It's a really difficult discussion to have, because realistically, there are only so many science stops we can make. It comes down to trading an interesting science goal in front of us for possibly *more* interesting science activities in the future, and I think it's espeically hard to come in new and want to do something immediately. Though we bring fresh perspectives, we might also lack the experience to know when something's not worth stopping for. This time, we're stopping, and I'm glad for now. If it turns out to be a stop for something we've already seen, everyone will be disappointed and we might have to skip something later too. But that's the nature of science, some roads lead to fabulosity and others dead-end unexpectedly.