As the little rover Sojourner on Mars continues futile attempts to rouse its stone-cold and silent mother ship, scientists at NASA's Jet Propulsion Laboratory Tuesday officially bid a reluctant farewell to the Pathfinder mission.
In sharp contrast to the exuberant atmosphere surrounding the landing on Mars just four months ago _ cheered on by NASA chief Dan Goldin and Vice President Al Gore _ the ending was much more subdued. Tuesday's expected telephone call from President Clinton never came. "He got distracted," said project manager Brian Muirhead.
Mission scientists reviewed panoramic images of the Red Planet taken in the early, heady days of the mission. "We come to praise Pathfinder, not to bury her," Muirhead said.
On Mars, meanwhile, Pathfinder has sent no science data since Sept. 27, despite engineers' efforts to re-establish communications. Since the spacecraft's electronic systems haven't been turning on to warm up the instruments, mission managers fear the Pathfinder has been literally frozen silent.
Without instructions from the Pathfinder, the rover continues to follow its built-in contingency plan, which directs Sojourner to head toward the center of the mother ship. The rover can't actually reach the lander, however, because its programed instructions also tell it never to come nearer than about 10 feet from the center. So it stops, moves around the lander for some distance, then tries to reach the center again the following day. Some speculate it may have dug a circular ditch around the lander.
Nevertheless, said Muirhead, "The mission is not over." He stressed that periodic attempts still will be made to contact the spacecraft and that much work remains in analyzing the data transmitted. However, he conceded that "the likelihood of hearing from the spacecraft again diminishes with each day."
Even if Pathfinder never sends another signal to Earth, it will have left a memorable legacy both in science and in the hearts of the public.
Among the most important scientific highlights, Pathfinder provided ample evidence that Mars was, indeed, a warm, wet world in ancient times. It very possibly once had standing water that carved smooth, round pebbles, sand grains, and left traces of long dried puddles and ponds.