The carbon dioxide was falling out of the air as dry sleet, little needle-like slivers of frozen gas, sticking to the supercooled metal surfaces, flashing back into gas when they hit the warmer water ice on the ground, only to freeze again in the thinning atmosphere. Overhead, the sun glowed dully red and huge, and shapes unresolvable by the mind's eye moved through the dry rain and darkness, on their own unknowable erands.