NASA officials Monday said they had exhausted all possible means of contacting their ill-fated Mars Polar Lander and now have no hope of finding the craft or determining exactly what caused its disappearance.
Expected to reach Mars on Dec. 3, the $165-million space probe was largely given up for lost a few weeks later after repeatedly failing to signal Earth. Still, many on the project team based at Jet Propulsion Laboratory in Pasadena held out hope that they would somehow contact the lander and quietly had been continuing rescue efforts.
Until Christmas, operators of space radio antennas were working around the clock, straining to hear any faint signal the craft might send out. Since then, with upgraded antennas exquisitely tuned for sensitivity, operators have been listening at times the craft was most likely to call in.
Mission engineers, meanwhile, have been sending the craft a steady stream of new commands to jiggle or turn its antennas in hopes of establishing contact.
None of it has worked.
"We've gone through every option we could on how we could establish contact with the vehicle and finished late last night," said Sam W. Thurman, who managed flight operations for the mission. "The simplest explanation is it's just not there."
While there is no way of knowing the fate of the lander, the two most common theories are that it arrived at the surface, but fell into a canyon or tipped over on uneven terrain or that it malfunctioned during its descent and never made it to the surface.
"Entry and descent landings are very complex. There are many things the spacecraft has to do properly," Thurman said.
Potential problems, he said, range from something as simple as a nut fastened too tight to overcorrection by the craft's sophisticated autopilot system.
Although some carry a faint hope that the Mars Global Surveyor now orbiting Mars might catch sight of the lander's 24-foot parachute, Thurman said it would be difficult to distinguish the white parachute from a patch of frost.
A sister craft, the $125-million Mars Climate Orbiter, plunged to an unknown fate near Mars in September. That loss was blamed on a failure to convert navigation measurements from English to metric units.
Two panels, one at JPL that oversees the $356.8-million Mars program and another at NASA, are scrutinizing both losses. Findings--and recommendations for the future of the Mars program--are expected in the spring.
A main question is whether efforts to speed progress and trim costs in the space program fatally compromised the missions.
"What's important is to learn every step of the way because there is a long-term commitment to exploring Mars," said Ed Stone, JPL director.
NASA officials had planned to launch their next mission to Mars, with a similar lander, in 2001. It is now probable that the lander will be redesigned and that the mission will be postponed until the next window for a Mars launch in 2003.
Hardened by disappointment, project leaders are nothing if not stoic. "You can't work in this business without being prepared for failure and if you can't mentally handle the failure, you probably should get another job," Thurman said.
Monday, the mission operations center that once was near-frenzied in its activity stood silent, much of the staff transferred to new missions, most computer terminals and video monitors dark.
The walls, though, were still plastered with colorful posters of the Martian landscape and one monitor glowed, the image of the Red Planet beckoning.
"This adventure is not over," Thurman said. "I want a chance to go back and do it right."