Mars Mission Ends With Whimper Brave Little Sojourner Can’t Wake Mother Ship

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 National Aeronautics and Space Administration 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 - like proud parents passing around graduation pictures. “We come to praise Pathfinder, not to bury her,” Muirhead said.

On Mars, meanwhile, Pathfinder has not sent home any science data since Sept. 27, despite the best efforts of the engineers to re-establish communications. Since the spacecraft’s electronic systems haven’t been turning on to warm up the insturments, mission managers fear the Pathfinder has been literally frozen silent. The end could have come in the form of a solder joint that cracked in the cold or a circuit malfunction, according to mission manager Richard Cook.

Without instructions from the Pathfinder, the rover continues to follow its built-in contingency plan, which directs Sojourner to head straight toward the center of the mother ship. The rover can’t actually reach the lander, however, because its programmed 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 that in these attempts to reach Pathfinder, it may have literally dug a circular ditch around the lander.

Where is Sojourner right now? “That’s what I ask every morning,” said rover scientist Jacob Matijevic. “It will wake up each morning and keep trying to get to the center of the lander,” each time being thwarted, he said, by Pathfinder’s virtual barrier. “My own speculation is that it drove up on a rock and is waiting for instructions from home.”

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 to be done analyzing the data already sent down. However, he conceded that “the likelihood of hearing from the spacecraft again diminishes with each day.”

Even if Pathfinder never sends another signal to its home planet Earth, it will have left a memorable legacy both in science and in the hearts of the general public. Since the moment the airbag-encased Pathfinder bounced down onto the surface of Mars July 4, the trip to the Red Planet has been as much a sentimental journey as a technical tour de force.

Pathfinder scientists made the rover’s adventures on Mars seem real to people by giving it human qualities, describing it “kissing” or “snuggling up to” a rock, “doing a wheelie,” or sending back “her” thanks to the taxpayers who supported her.

The rover was name after black civil rights champion Sojourner Truth.

At the same time, the researchers brought the surface of Mars to life with spectacular 3-D images and fanciful names for the rocks - many of them namesakes of familiar cartoon characters such as Yogi Bear and Casper the Ghost.

Among the most important scientific highlights, Pathfinder provided ample evidence that our sister planet 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.

Most of all, the rover proved that an independent, mobile robot can get around on Mars, take pictures, analyze rocks, survey the territory, avoid obstacles and navigate on its own.

Sojourner has far exceeded its planned one-week “primary” mission, and Pathfinder’s terminal chillout is pretty much the end its designers had expected.

Still, until future Mars missions happen by for a closer look, no one will know exactly how Sojourner and its mother ship spent their final hours.

“The only evidence may be that we’ll see the lander with a little trough around it, ” Matijevic said.

MEMO: This sidebar appeared with the story: MISSION TO MARS Highlights of the just-ended Mars Pathfinder mission: Launch - Dec. 4, 1996, from Cape Canaveral Air Station. Lands on Mars - July 4, 1997. Rover rolls to surface - July 6, 1997. Rover examines first rock - July 7, 1997. Last scientific data from Pathfinder - Sept. 27, 1997. Last contact from Pathfinder - Oct. 7, 1997. Mission ended - Nov. 4, 1997.