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

The recent discovery of bacteria on Earth in the most unlikely spots-under the ocean floor, in rivers orange with dissolved iron-has lent support to the argument that if life can make it there, it can make it anywhere. The technical term for these almost perversely hardy bacteria is "extremophiles."

Pittsburgh team leader Nathalie Cabrol, who radiates the toughness of an expedition climber, would seem to be their human counterpart. When the Zo mission ends in mid-October, she will say goodbye to the Holiday Inn, and, again under the aegis of NASA, make her fourth ascent of the 19,731-foot Lincancabur volcano on the eastern side of the Atacama. "I´m not a daredevil," she tells me in accented English, "but I am free-diving in lakes at 20,000 feet, so you understand where I am coming from." At an altitude that would tax most people´s ability to stay upright, she intends to dive into a crater lake near the summit to measure with various instruments the lengths to which life will go to stick around."I´ve been around the block, the extreme block, a couple times, and I have yet to find a place where I didn´t find life," she says. "Everywhere you find a hurdle, you find a way life found to get around it."

Zo and the Boys

The wind is a steady 25 mph, and the temperature is mild even if the sun is burning a hole through our silly brimmed hats. Today conditions are pretty good in the Atacama for people-though not for robots. "I think the plan was to shoot the gap between these hills," Wettergreen tells a new arrival, "but the science team´s heading was a little off. They said something about flats, and there aren´t any around here, so we´re gonna call it a day when the robot runs into something it can´t handle."

Zo has two stereoscopic cameras about two thirds the way up its mast that possess a 60-degree field of view. Like human eyes, they provide depth perception. Since the mast turns as one unit with the front axle, whatever direction Zo goes, it "sees" seven meters ahead, and it takes five photographs of the terrain roughly every second. One of its three onboard computers evaluates those seven meters, and adjusts direction and speed accordingly, before being presented with the next seven meters-and a brand-new set of decisions to make-a fifth of a second later.

The contours of the Atacama have been sculpted by wind and water over millennia. Today Zo has been nobly traversing the edge of a drainage channel. But following the merciless dictates of the Pittsburgh scientists´ plan, it is now being asked to climb the channel´s bank, some 10 feet high. Its wheels dig into the soil, and it moves upward like a mountain goat for a couple feet before losing traction and sliding down. The robot tries again at a slightly different attack angle, and again and again. It´s like watching a bad but determined driver attempt to parallel park. As Wettergreen puts it, "Zo is very persistent based on its limited knowledge."