If you want to power a rover across an alien landscape, solar is the way to go—no fuel tanks required. But solar energy flows only while the sun is shining, a problem if NASA wants to send robots on long Mars expeditions. David Wettergreen and his colleagues at Carnegie Mellon University's Robotics Institute have a solution: Hyperion, a six-foot-seven-inch-long machine that moves strategically to remain in the light and keep its eight-and-a-half-foot tall solar panel perpendicular to the sun.
Hyperion's software knows the local topography and anticipates the changing position of the sun. "By looking at the terrain, it projects how much power is required and where shadows will fall. Then it determines the best time to visit various locations," Wettergreen says. The robot isn't fast enough to chase the sun at the equator, but a similar machine could do fine exploring the intriguing landscape near the Martian poles. In tests last summer near the Arctic Circle—where the sun never sets but moves in a large circle in the sky at that time of year—Hyperion successfully tracked the sun and kept its batteries fully charged over a 5.6-mile circuit. Wettergreen will soon start working with the Jet Propulsion Laboratory to adapt Hyperion's software for Mars duty.
Roving around desolate Devon Island in Canada, Hyperion keeps its solar cells aimed skyward.Photographs courtesy of Carnegie Mellon University/Robotics Institute