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Tiny Mars rover set to take giant roll for mankind


Mystery glitch that threatened mission fixed

July 5, 1997
Web posted at: 11:08 p.m. EDT (0308 GMT)

PASADENA, California (CNN) -- NASA scientists are getting ready to send off Pathfinder's tiny rover on its historic mission to roam the desolate, rock-strewn surface of Mars.

Saturday night, commands were sent to prompt Pathfinder's landing vehicle to lower the ramps that the rover, Sojourner, will use to roll down to the Martian surface. The rover, which has been stored in a compact position, will also rise up to its full size -- only about as big as a microwave oven -- prior to deployment.

The actual descent of the rover is scheduled to come two to three hours after the ramps are lowered. When that happens, it will mark the first time that a mobile spacecraft from Earth has driven over the surface of another planet.

Pathfinder image gallery Opinion Poll: Mars Exploration

However, at least in the beginning, Sojourner won't wander very far afield.

"For the first couple of days, we'll really just have a learner's permit, relative to driving the rover. It will take us a couple of days to get our sea legs," says rover system engineer Matt Wallace.

"We'll just drive down the ramp, and we may do a small turn, but very little other than that," he said. Scientists also will activate an instrument on the rover, called an X-ray spectrometer, that can evaluate the chemical composition of rocks and soil.

Pathfinder project manager Tony Speer also announced Saturday night that the Pathfinder lander has been named Sagan Memorial Station in honor of the late astronomer Carl Sagan.

Rover descent would mark end of dramatic day

If the rover deployment goes off as planned, it will be a welcome end to a day of drama that threatened to cast a cloud on a space mission that had been exceeding expectations.

Late Friday evening -- hours after a flawless landing on the red planet's surface -- scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, discovered that only the smallest bits of information were getting through from the rover to the lander. That could have hampered the ability to move the rover around the Martian surface.

The JPL team labored all day Saturday to correct what they believed was a software problem in a communications modem. Just before 7 p.m. EDT Saturday (2300 GMT), they began to receive data sent from the rover to the lander to Pasadena, indicating that their efforts had been successful.

Cheers and high-fives erupted in Mission Control, as someone exclaimed, "We're alive, we're alive."

At a press conference a short time later, NASA scientists were at a loss to explain what caused the communications problem -- or what fixed it. The leading theories are that switching to a backup power supply for the lander's modem or shutting down the rover's systems for its usual nighttime hibernation may have been what did the trick.

A computer system on the lander also shut down and reset itself sometime during the Martian night. Mission manager Richard Cook said, "We're a little perplexed as to what happened," but he said it should not have any detrimental effects on the Pathfinder mission.

Rover is centerpiece of Pathfinder mission

The rover is the "gee whiz" centerpiece of the mission. And the communication link between it and the lander was an essential element in its success, because commands to the rover from Earth are sent through the lander.

If it is cut off from communication with Earth for an extended period of time, Sojourner has been programmed to eventually begin rolling on its own, using preset data stored in its memory. But NASA scientists clearly preferred not to resort to that backup plan.

"We would prefer to try to command that activity, as opposed to letting the rover make up its own mind to do this itself," said Jacob Matijevic, rover manager.

NASA analyzing Mars images

NASA officials have been busy analyzing the images being sent back by Pathfinder, which they started receiving about 9:35 p.m. EDT Friday (0135 GMT Saturday). So far, engineers say they have been able to make several interesting observations:

  • The rocks in the photographs slant toward the northwest, indicating that a flood could have oriented them in that direction. The pictures were taken in a flood plain.

  • The soil contains more than one color, meaning "there's definitely two types of soil here," according to Peter Smith, the principal manager for the Pathfinder imager.

Officials also said they were perplexed by an object in one of the photographs.

"The most mysterious thing in this picture is this little object on the horizon that has been likened to a couch," Smith said, pointing to the object. "Somebody suggested there was a homeless person camped out there."

He said he believed the squiggly object might be one of the parachutes used to help Pathfinder slow down during entry. But, he said, geologists believed it was a fascinating rock that needs to be investigated further.

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