Is This the Machine That Will Finally Find Life On Mars?

Cabrol is unfazed. "I think we are pushing doors, one by one," she says. "This is more of a proof of concept." Zo has made considerable strides. Last year the camera box was so much less sophisticated that every time the robot stopped for fluorescent imaging, Waggoner, who is 64, had to get down on his hands and knees to squirt water and dyes (then only two) from common garden spritzers.

My last day with Zo, October 9, the robot is heading to work with three of the team´s 4x4s following behind when we meet a truck carrying the mine´s security staff. Far from being nonplussed by the robotic procession, they regard Zo as something of a local celebrity. "This is a great thing for humanity, to test a robot in Chile," the driver says in Spanish. "I´m taking a photo now so when this robot goes to Mars, I can show my friends." After the Chileans depart, Chris Williams shakes his head.

"I´ve said this many times. This robot is not going to Mars," he says. "But the technology may." Such is the fate of a robotic prototype and the tenor of an engineer´s "show me" pragmatism. Back in Pittsburgh, though, Nathalie Cabrol sees Zo´s fledgling efforts in a grander light: "Thousands of generations have been wondering about life elsewhere. Were they disappointed that they didn´t get a response? The answer is, they kept asking the question. What is different is that our generation might have the technological ability to find it."

Joseph Hooper, a PopSci contributing editor, writes frequently about robotics.