Since I've been involved in this project, we’ve been steering Spirit down the southern flank of Husband Hill and into a basin. Up against the leeward side of many of the hills in this area are vast (from the rovers’ perspective) black dunefields. They’re black because they’re not covered with the ubiquitous red Martian dust, which means they must be relatively young or frequently moving. They’re also probably black because they’re basaltic.
We had a team meeting to decide whether we wanted to spend a couple of weeks heading for one of these dunefields near us, called El Dorado. There are several members of the team interested in aeolian processes (how sand moves) and physical properties of the martian surface (which might be very different in fresh dunes vs old soil), who are eager to go. But what convinced me to get on board was the fact that El Dorado is visible from several orbiting spacecraft. It’s an exceptional opportunity to collect real Martian ground-truth to help interpret orbital data, a topic about which I’ve been known to kvetch.
So down through the rocky, desolate Indian country Spirit went, trading among the Apaches and Comanches, heading southwest on the path to El Dorado. The rover planners outdid themselves again, with some lengthy beauties of drives topped off with a scuff right on a dune face. And here we'll spend a long holiday weekend with the arm out, using all our instruments in chorus on the black sands of El Dorado.