Radar for rovers on future Mars trips?

Scientists are developing ground-penetrating-radar equipment that could serve as geologists' helpers on future Mars-roving vehicles.

The antenna that transmits the ground-probing signals for such a system could be built into a 50-centimeter-square patch on the rover's undercarriage, says Kevin K. Williams, a geologist at the Smithsonian Institution's National Air and Space Museum in Washington, D.C. The electronics that would emit radar pulses and interpret their reflections would consume only 6.5 watts of power--little more than a child's nightlight. Altogether, the equipment could weigh less than 3 kilograms.

Williams and his colleagues have already tested prototypes of such radar gear in Marslike environments here on Earth. At Sunset Crater, Ariz., the radar easily distinguished layers of congealed lava from those of loose volcanic ash several meters underground. At an Arctic test site, the radar could distinguish solid ice from frozen sand at depths as great as 9 meters.

Radar data collected during a day's roving on Mars would probably occupy less computer memory than one high-resolution digital photo does, says Williams. Nevertheless, that information--together with images of the Red Planet's surface taken by rover-based cameras--could enable scientists on Earth to scan the Martian terrain for buried ice or to better identify interesting sites for robotic drilling or digging.--S.P.