July 12, 1997 in Nation/World

Pathfinder’s Day Real Yawner, As Wires Get Crossed

Knight-Ridder
 

Like a jet-lagged traveler, the Pathfinder lander overslept and missed a whole day’s work on Mars, embarrassed ground controllers admitted Friday.

The fault was a poorly timed wake-up call from Earth, which arrived in the predawn Martian darkness, 11 minutes before Pathfinder was scheduled to turn on its radio receiver.

The missed connection was the second minor mishap to mar the Mars mission after a near-perfect start. It left Sojourner, the roving robot, with one wheel hung up on a boulder named Yogi for a second day.

Engineers at NASA’s Jet Propulsion Laboratory in Pasadena insisted that no harm was done by the communications mix-up.

“The spacecraft is fine, the rover is fine, and we’ll catch up,” said Richard Cook, the Pathfinder mission manager.

About 50 megabytes of scientific and engineering data - enough to fill 37 floppy disks on a personal computer - remain safely stored in Pathfinder’s computer memory and will be downloaded later, he said.

The activities planned for Friday - including backing Sojourner down off of Yogi and steering it toward its next target, a whitish rock called Scooby Doo - were postponed until today.

“On the seventh day, we decided to rest,” Cook said. For the first time in a week, “everybody got a lot of sleep. They appreciated it.”

Explaining how the mistake occurred, Cook said the Pathfinder is programmed to turn itself off during the night, when its solar panels are not generating energy, to save its batteries.

It is supposed to turn itself back on at a preset time, which changes by 37 minutes daily as Mars moves around the sun. Mistakenly, JPL engineers tried to contact Pathfinder 11 minutes before it woke up. When it did wake up, it was unable to locate Earth, a tiny dot in space 120 million miles away.

“Unfortunately, we made a little mistake,” Cook confessed at a news conference.

Engineers tried to regain contact with the spacecraft but gave up after a while.

“If we miss the beginning, it’s a scramble to try to catch up,” Cook explained. “So we decided not to take any chances, scrub and go back for another approach today.”


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