On a roll: robot attempts desert voyage.

When a burly four-wheel-drive vehicle set off across Chile's Atacama Desert this week, its driver was nowhere in sight. The semi-autonomous rover, called Nomad, takes its marching orders from engineers and members of the general public sitting thousands of kilometers away in North America.

Moving at less than 1 mile per hour, the robot is a prototype of the kinds of planetary explorers that may gather Martian rocks in the next century or hunt for meteorites in Antarctica, says William "Red" Whittaker, whose team developed the rover at Carnegie Mellon University in Pittsburgh. Nomad's 6-week journey comes at an auspicious time, overlapping with the Mars Pathfinder mission, which is scheduled to touch down on the Red Planet with its own small rover on July 4.

Whittaker chose the Atacama Desert for testing Nomad because the region has virtually no vegetation and a landscape similar to that of the moon or Mars. "The Atacama Desert is the place on Earth most like another planet," he says.

Funded mostly by NASA, the Nomad project has a goal of traversing 200 kilometers of desert terrain with the robot under remote supervision. Roughly the size of a compact car, the rover's large aluminum wheels can turn independently and extend out from the chassis for added stability on uneven terrain. It has three sets of stereo cameras in front and a 360 [degrees] panospheric camera that enables remote drivers to see all around the robot.

While visitors to the Carnegie Science Center will be able to pilot Nomad, others can track its progress over the World Wide Web at http://img.arc.nasa.gov/ Nomad/nomad.html and at http://www. ri.cmu.edu/atacama-trek/.

Scientists at the NASA Ames Research Center in Mountain View, Calif., plan to spend a week testing Nomad in three mock missions designed to simulate rock collecting on Mars, long-distance exploration on the moon, and meteorite collecting in Antarctica. Within the next 2 years, the Carnegie Mellon team plans to take Nomad on a meteorite-hunting trip in Antarctica to determine whether the robot can detect buried meteorites that get overlooked by human collectors, says Whittaker.

Veteran Antarctic researchers, however, are not holding their breath. When Whittaker last brought a robot to Antarctica, in 1992, the eight-legged machine called Dante walked only a few steps before it was crippled by a broken fiberoptic cable (SN: 1/9/93, p. 22).

Ralph Harvey of Case Western Reserve University in Cleveland, who has spent 21 field seasons searching for meteorites in Antarctica, says that robots could help in limited ways. "A robot can work on days that would make a human feel pretty uncomfortable, such as when the winds get above 20 knots and the air temperature drops below 20 [degrees] below zero."

In better weather, though, robots will not be able to match humans' ability to pick out the few meteorites amid the thousands of terrestrial pebbles in many locations. "There is simply no tool for finding meteorites as good as the human brain and eye," says Harvey.