"Well, there's a ridge either side of us, but it's pretty forbidding, at least from this angle," Hobbie says, squinting into the dust, "Don't know how good you are at rock-climbing, but most of mine's been done in the gym, with a harness."

Meaning he's not likely to want to go scurrying up sheer cliffs anytime soon.

"I'd kill for any sign of life, really. We're going to need water soon."