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Rover backs away from Yogi, faces serious test
'When your baby's not talking, you worry'
July 12, 1997
Web posted at: 12:49 p.m. EDT (1649 GMT)PASADENA, California (CNN) -- After days of being stuck on a rock named Yogi, the Mars Pathfinder rover rolled away from the Martian boulder Saturday and prepared to study its chemical composition.
But NASA scientists had little time to celebrate as they scrambled to determine the cause of a communications glitch between the lander and rover that has delayed the red planet probe.
"Not knowing what's going on makes you a little bit nervous," said Brian Muirhead, deputy project manager at NASA's Jet Propulsion Laboratory.
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41 sec./750k QuickTime movie"When your baby's not talking to you and you think she might be sick, you worry," he said. "She's just fine now, but we do have this software problem that we will have to get to the bottom of."
The six-wheeled Sojourner was expected to begin "sniffing" the rock's chemical composition with its alpha proton X-ray spectrometer, barring further computer malfunctions.
Serious software glitch
The most serious glitch occurred late Friday when the bug in software that controls communication between the rover and the Pathfinder lander caused a computer to reset.
That triggered the probe to automatically search for instructions from Earth using its low-gain, or slow-speed, antenna. Scientists, who were focusing on the spacecraft's high-gain antenna, were briefly disconnected.
Contact was re-established through the antennas.
"The problem will be if the software bug bites us again," Muirhead said. "Then we will just go ahead and get the camera images and hold off on doing anything with the rover until we get the software problem fixed."
A similar glitch occurred on the first night of the week-old mission. Software team chief Glenn Reeves suspected a bug in the program that controls communications between the rover and lander.
Data not lost
The delays began two days ago when Sojourner moved too close to Yogi and one of its wheels got stuck on the side of the rock. Sojourner's spectrometer was too far away to touch the rock.
Scientists ordered Sojourner to back away from the rock and approach it again, but the commands never got to Pathfinder. Its radio receiver had been turned on 11 minutes too late because of a human error.
The receiver, which relays signals to the rover, is turned off at times to conserve energy. Scientists have one chance each day to radio commands to Mars.
The error delayed the collection of a full day's worth of data from Mars, including landscape pictures, weather and atmospheric data. All that came down was confirmation that the spacecraft was operating and healthy.
No data was lost because it was stored in the spacecraft's memory, said mission manager Richard Cook.
The rover was designed to operate for a week on Mars, but scientists now believe it might last up to a month. Barring death or more communications problems, the Sojourner is next to conduct tests of a whitish rock named Scooby Doo.
The Associated Press contributed to this report.
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- Pathfinder Landing Timeline
- Mars Pathfinder Mission
- Mars Global Surveyor
- Jonathan's Space Home Page
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