A Fiery End for Mars Satellite

Dick writes about Earth and planetary science for Science magazine.

Early this morning, engineers at the Jet Propulsion Laboratory (JPL) in Pasadena, California, were stunned to discover that the Mars Climate Orbiter (MCO) spacecraft, presumably entering orbit for a 2-year mission to study martian weather, had dipped too far into the atmosphere on its arrival and perished. "It came in lower than expected," Project Manager for Operations Richard Cook of JPL told a press conference, "resulting in the loss of the mission."

The catastrophe was all the more astonishing for its apparent cause. "It looks like something was wrong with the groundbased navigation," said John McNamee, project manager for spacecraft development at JPL. Universally regarded as the best in the world, JPL's navigation team takes tracking data beamed back from a spacecraft and determines its position so that short burns of the onboard rocket engine can bring it on target.

Yesterday, after four such burns, the navigation team members thought they knew the location of MCO to within 20 kilometers--and it appeared to be on target to pass 160 kilometers above the martian surface, safely skirting the atmosphere before going into orbit. But in the final hours before arrival, spacecraft controllers began to realize that MCO was coming in 100 kilometers too low--a huge error. By then it was too late to fire any thrusters to save the craft. "We're ruling out a spacecraft problem and looking at the possibility of human error and software problems," said Cook.

Although team members continue to listen for any radio signals from the $87 million spacecraft, they assume its brush with the martian atmosphere overheated it or tore off parts. Planetary scientists will have to live without observations of clouds, dust, and water vapor that would have helped them understand the martian hydrological cycle. But it could have been worse: Mars Global Surveyor, which has been in martian orbit for 2 years, will continue to return images of clouds and dust as well as fill in as a radio relay station between Mars Polar Lander and Earth when that probe rockets onto the surface in December.

The most immediate impact of the disaster may be felt on Capitol Hill, where this week scientists are trying to head off deep cuts in NASA's space science budget. "This isn't going to help," observes one scientist.

Posted in Space