Her feet crunch into the red crust. She hops tentatively, testing the feel of one-third gravity. Then a second hop, higher and more playful. Nice. Looking back she sees her spacecraft resting in a shallow depression. Squat and small, it looks like a toy. A shadow of anxiety crosses her mind. With all the trade-offs, cuts to NASA, the needs of national security, it was this or nothing: a single person sent to Mars to bring back samples. A robotic clone of her spacecraft stands ready for launch, but she knows the odds of a successful rescue are long. She's one hundred times farther from Earth than anyone in history. Utterly alone.

Yet there is nowhere else she would rather be. The geologist gets to work. Her trained eye scans the alluvial plain and settles on one particular outcropping. She moves toward it in an awkward loping motion. It's difficult to judge distances through the thin atmosphere laced with dust, where ochre rocks shade into an apricot sky. An hour later, she is there, with only the sound of her breathing for company. Along one slope of the outcropping, a raised seam, split like a wound, exposes the layers below. Perfect.