SAN FRANCISCO — Evidence of ancient Martian ponds and a developing mega storm - big enough to cover the Earth's South Atlantic - are among the serendipitous fruits of a NASA mishap.
The Global Surveyor, a spacecraft carrying sensors and cameras to map the Red Planet, has not been able to properly deploy its solar panels. As a result, it has been forced temporarily into a lower orbit.
The orbit is producing a closer look at the planet's surface and providing the "first good evidence" that there once was standing water on Mars, says planetary scientist Arden Albee of the California Institute of Technology in Pasadena. The presence of water, also indicated by the Mars Pathfinder mission, is considered crucial to the development of life.
Tracking Big Red
Scientists are also tracking a Martian dust storm that blew up out of the southern hemisphere over the past two weeks and now covers 20 percent of the planet surface. Researchers, speaking at the fall meeting of the American Geophysical Union here, were divided over whether the storm will continue to grow. But scientists are getting the best look ever at how the Martian climate and atmosphere work, according to Dr. Albee. That understanding could help in the planning for future missions and provide insights into weather systems on Earth.
Albee says that the new data coming in have "changed our view" of Mars in "significant ways."
Displaying photos relayed to Earth by Global Surveyor, image analyst Mike Malin of Malin Space Science System in San Diego, explained that the camera has spotted terrain where surface formations strongly suggest that a kilometer-wide shallow pond of liquid water once stood.
He also showed views of a valley deeper and steeper than Earth's Grand Canyon. They reveal what Dr. Malin called "unexpected" multiple layers along the valley. Some layers are dark. Others are bright. Some form cliffs in stair-step fashion. The team now has data from 18 low orbits over Mars' north pole. Scientists hope to find an explanation for this layering as more data accumulate.
Another unexpected finding is that, while Surveyor has detected no general magnetic field, Mars does have regions that are magnetized. What's causing this strange magnetic pattern "is a true mystery," Albee says.
Meanwhile, members of the Mars Pathfinder team reported the full results of last summer's spectacular lander and rover mission. They have given many preliminary accounts through news media. Now, for the first time, they made a formal presentation to fellow scientists. Research papers on the mission were published in the Dec. 5 issue of the journal Science.
Pathfinder project scientist Matthew Golombek with the California Institute of Technology's Jet Propulsion Laboratory (JPL) in Pasadena says that Pathfinder data suggest that "maybe we had a warmer and wetter past" on Mars. He calls this finding "very strong" evidence" for the value of "research into past life on Mars." It is based partly on identification of pebbles and cobbles whose markings and shapes suggest the action of running water.
JPL, which manages the Pathfinder mission for the US National Aeronautics and Space Administration, has decades of experience in planetary exploration. Yet the accuracy with which its planners predicted the nature of Pathfinder's landing site was "something we couldn't have done before," Dr. Golombek says. Using remote-sensing data, analysts correctly predicted the site would be safe for landing and roving yet would have a variety of rocks deposited by past floods to study. He calls this feat "nothing short of miraculous."
Golombek noted that another major result is pinning down the size of Mars' central metallic core. Previously. scientists couldn't tell if Mars even had a core. Now, he explained, it is clear that Mars does have a core that is between 1,300 kilometers and 2,000 kilometers in radius.
In short, Pathfinder returned more than 16,000 images from the Carl Sagan Station (the lander) and more than 550 images from the rover.
The weather boom on the lander made 650,000 combined pressure, temperature, and wind measurements of Martian weather. The rover, called Sojourner, made 16 chemical analyses of nine rocks plus soil samples. Now planetary scientists await more data from the orbiting Surveyor to help them fit Pathfinder's results into the larger Martian picture.