U.S., European Mars missions looking for life

NEW YORK (AP) — Four spacecraft sent by the United States and Europe are either on Mars or circling it looking for signs of past life on the frozen planet:

— The European Space Agency’s Mars Express was launched from Kazakhstan in June. Its mission is to map the planet, using a powerful radar to probe the top few miles (kilometers) of its surface for evidence of water, and measure water concentrations in the atmosphere. It has been transmitting pictures since earlier this week.

— Britain’s Beagle 2 lander, carried by Mars Express, was released toward the surface of Mars on Dec. 19. It hasn’t been heard from since its scheduled landing on Dec. 25. Its mission was to dig into Mars to hunt for organic materials and sniff the atmosphere for traces of methane produced by living organisms.

— NASA’s twin robotic rovers, Spirit and Opportunity, are designed to be robotic field geologists hunting for evidence of past water activity. They seek to find out if Mars was ever hospitable enough to allow life to gain a toehold.

Spirit landed on Jan. 3 and enthralled scientists with its sharp pictures from the surface. It began moving Jan. 15, but on Wednesday stopped communicating. Its twin, Opportunity, is set to land on the other side of the planet from Spirit late Saturday night.