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STANFORD -- Satellites are easier to handle in space than on earth. And a lot harder to control.

In the frictionless, free-fall environment of space, moving a huge satellite requires no more than a push. Controlling its movement and guiding it, however, creates immensely difficult problems for humans accustomed to the dynamics of objects on Earth.

Stanford's aeronautics and astronautics department's Automated Robotics Laboratory may have come up with a workable solution: robots that could build space stations, rescue satellites and perform repairs on spacecraft.

The $12 million robot project, a joint venture of the Automated Robotics Laboratory with NASA, plans to put a fully operational robot in space in three to five years time.

In a lab designed to simulate space, Kurt Zimmerman, a doctoral student in electrical engineering, demonstrated how the robot is to work in space. From his computer terminal, he commanded the robot to "capture" another object.

The resulting show looks like a scene straight out of Star Wars. The robot floats smoothly across a granite surface, following the target object. It stretches its long arms; the probes at the end of the robot arm play a short game of dodging with the slowly spinning target object; then two probes latch on to predetermined spots on the object.

The robot will maneuver in space with the help of cold-gas thrusters. Sensors will detect color patterns or a light source on "targets" like satellites.

"After an astronaut points the robot in the direction of the target satellite from a remote station, it will navigate its path in space using the same satellite-guided Global Positioning System that American troops used during the Gulf War," said Robert Cannon, Charles Lee Powell Professor of Aeronautics and Astronautics and former chair of the aero/astro department.

Using information from 24 satellites stationed at different points in space, the robot can compute its exact position in relation to a target satellite.

Marc Ullman, an astronautical engineering student, built a two-dimensional simulation of space in a basement room.

He moved a huge, smooth slab of granite into the lab. The robot then was built to float over this surface. It levitated on an air pad three- thousandths of an inch thick to simulate a two-dimensional form of zero- gravity space.

"Moving the granite slab into the lab was harder than getting the robot to 'float' over it," Ullman said. "We had to take down a temporary wall to move the 18-ton slab into the lab."

Ullman brought other talents as well to the research project. A cellist, he developed the "theme music" for the video recording of the robot's glide across the granite surface - a composition by the French composer Camille Saint-Saens.

The project's potential applications include a drastic cut in costs, with robots performing longer and better in space than can astronauts in rescuing satellites or building space stations, said Ed Wilson, a mechanical engineering student involved in developing neural network-based technology to add onto the robot.

Robots in space also would mean fewer risks to astronauts and far less spending on costly safety measures.


This story was written by Shankar Vedantam, a science writing intern at the Stanford News Service.


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