Pathfinder’s Communication Mishaps Halted

After a weekend of “troublesome” communications snafus, the Mars Pathfinder appears to be back in synch with its ground controllers, Mission Manager Richard Cook said at a press briefing Tuesday at the Jet Propulsion Laboratory in Pasadena.

A combination of new software beamed up to the spacecraft and the leisure to plan ahead should prevent future miscommunications, he said.

During the first weeks of the Pathfinder’s adventures on the Red Planet, mission controllers had to continually alter its instructions to NASA’s Deep Space Network, the antennas in Spain that pick up the spacecraft’s signals. These signals shift frequencies as Mars drifts away from Earth, as the temperature on Mars varies and as the type of data being sent down changes.

Until now, the network’s antennas have had no advance notice of such changes because JPL has been too busy reacting to events on Mars to think more than one day ahead. “We ask the DSN to do different things every day,” said Cook. “One problem begat another.”

Monday night, however, JPL was able to plan the activities for Pathfinder two days ahead, “a major accomplishment,” he said, allowing the antenna network to make the frequency shifts necessary to stay in tune. The Monday transmission appeared to work perfectly, he said. “I think we’re back on track.”

Meanwhile, the one-foot-high rover Sojourner wandered through a rocky field called the Cabbage Patch and took chemical analyses of soil. The data that could not be sent over the weekend was stored in Pathfinder for transmission at a later date.

Rover scientist Henry Moore reported that Sojourner said “she was having a ball” on Mars, but “beginning to get the itchies” to go and explore.

On Monday, Sojourner sent back its analysis of Scoobie Doo, a rock with a white crust on top, like a frosted cake. The same whitish material is seen in places where Sojourner has dug its wheels into the fluffy Martian soil, exposing rock underneath.

The six-wheeled rover also scratched its cleated wheels along Scoobie Doo’s surface in a “scuff test,” without much visible result. “We tried to do as much damage as possible,” said project scientist Matthew Golombek.

Next stop for Sojourner will be a patch of dark dirt in front of a rock called Lamb, then on toward the rocks Cradle and Souffle. In a week or so, it should make its way toward an area of slanted slabs called the Rock Gardens, where it will analyze Flat Top and Half Dome.

While some researchers would like to see it venture farther, Golombek couldn’t see any reason to explore far horizons when “you have everything you need right in your own backyard.”

The Imager for Mars Pathfinder, or IMP, showed off a high-resolution view of the stripes that scour the lower of the Twin Peaks on the horizon. Scientists still haven’t had time to deduce the history of the horizontal markings, but suspect that they were left by a series of ancient floods, like watermarks on flooded houses.

IMP’s now completed 360-degree view called the Gallery Pan revealed the entire landscape around the Pathfinder in three colors. A full-color, three-dimensional view should be completed in the next week, said IMP scientist Peter Smith.

At least three distinct types of rocks appear to be scattered about the landscape: those with the strange whitish material, rounded rocks like the bear-shaped Yogi that probably got their edges scrapped off when they were carried to this site during ancient floods, and darker, angular rocks, such as Barnacle Bill, knocked out of craters by meteor impacts.

The Martian dust appears to be highly magnetic, said Smith, unlike anything on Earth. “It’s not an earthlike environment,” he said. Researchers don’t yet know what the highly magnetic mineral could be.

IMP also saw little clouds in the Martian sunrise. While the researchers would love to find water clouds on Mars (any evidence of water would boost the potential for ancient life), these clouds could just as well be dust, said Smith. IMP images also showed clear “footprints” of Pathfinder where the balloon-encased spacecraft landed on Mars, bouncing and rolling gently to a halt and upsetting several rocks.

In perhaps the most significant finding for future Mars missions, it appeared that the Pathfinder’s solar panels did not accumulate enough dust to interfere with its power supply, as feared. As the first solar-powered spacecraft on another planet--and a very dusty planet at that--the Pathfinder and its rover both depend on sunlight, and engineers worried that the constant rain of dust on Mars might block out their energy source.

“We’re very pleased,” said rover scientist Geoffrey Landis, who added that he really wasn’t surprised that the rover didn’t kick up a lot of dust during its snail-paced crawl across the Martian surface. “We’re not operating a drag-racer here,” he said.