Radio disturbance stalls Phoenix's prospecting on Mars

Peter Smith, a principal investigator for the Phoenix, talked to reporters yesterday about the Mars lander's progress. (David McNew/Getty Images)

LOS ANGELES - Prospecting at Mars's north pole was set back at least a day yesterday when a communications link to NASA's Phoenix lander, nestled into a wide, undulating expanse nicknamed Green Valley, was interrupted by what spacecraft operators called a "transient event."

The event, caused by a cosmic ray or some other high-energy particle, knocked out the UHF radio on the Mars Reconnaissance Orbiter, one of two spacecraft circling Mars that relays computer commands between Phoenix and Earth.

The interruption occurred as operators were attempting to test the nearly 8-foot-long robotic arm that is scheduled to begin digging into the Martian plain in the next few days.

Rich deposits of ice are thought to lie inches below the lander. Such deposits could provide clues to whether Mars once was, or still might be, habitable for simple life forms.

Fuk Li, manager of the Mars Exploration Program at the Jet Propulsion Laboratory in La Canada Flintridge, Calif., emphasized that the problem does not affect the lander.

"Phoenix is healthy; everything is fine," he said.

Li said engineers were attempting yesterday to turn the radio back on. But even if that is unsuccessful, they could uplink the same commands to another NASA spacecraft, Mars Odyssey, which also could pass them on to Phoenix.

Odyssey and the Mars Reconnaissance Orbiter carry similar communications equipment, but engineers prefer to restart the radio on the Mars orbiter before switching to Odyssey because computer commands are lined up like customers at a check-out stand. Switching to the other spacecraft would mean reordering an entire set of commands, not just one.

Phoenix arrived on Mars Sunday after a 296-day journey through space. The $420 million mission is the first to land successfully on Martian soil since the arrival of NASA's twin rover, Spirit and Opportunity, in 2004.

Before the problem occurred, Phoenix's mast camera, extending about 7 feet above the Martian surface, captured fresh images of the checkerboard landscape of ridges and troughs that is caused by the movement of the ice beneath the surface. Scientists hope to dig into one of those troughs to unravel the history of water on Mars.

Phoenix also sent back a weather report for its home 171 million miles from Earth. The temperature ranges from minus 22 degrees Fahrenheit at midday to minus 112 degrees in the early morning.