Two Robot Rovers Now Stand on Mars

PASADENA, California, January 27, 2004 (ENS) - A small impact crater on Mars is the new site of NASA's Opportunity robot rover, and a larger crater lies nearby.

Opportunity returned the first pictures of its landing site early Sunday, about four hours after reaching Mars. The pictures indicate that the spacecraft sits in a shallow crater about 20 meters (66 feet) across. Scientists value crater locations which offer the means to see what lies beneath the surface of the red planet without digging.

"We have scored a 300 million mile interplanetary hole in one," said Dr. Steve Squyres of Cornell University, Ithaca, New York, principal investigator for the science instruments on the two NASA rovers now on Mars.

Camera on board the rover Opportunity took this image of the Martian crater where the robot landed Sunday. In the foreground is part of the rover's landing platform. (Photo courtesy NASA/JPL/Cornell)

Encouraging developments continued for Opportunity's twin rover, Spirit, on the opposite side of Mars. After weeks of sending back hundreds of images, Spirit shut down. NASA scientists say Spirit's flight software is not functioning normally. It appears to have rebooted the rover's computer more than 60 times in the past three days.

But now engineers have determined that Spirit's flash memory hardware is functional, strengthening a theory that Spirit's main problem is in software that controls file management of the memory.

"I think we've got a patient that's well on the way to recovery," said Mars Exploration Rover Project Manager Pete Theisinger at NASA's Jet Propulsion Laboratory in Pasadena.

Now humans have three views of Mars - the two rovers, view from NASA's Mars Odyssey orbiter circling the red planet.

Back on Opportunity's side of Mars, NASA selected a general landing area within a region called Meridiani Planum because of extensive deposits of a mineral called crystalline hematite, which usually forms in the presence of liquid water.

The main task for both rovers in the next three months is to explore the areas around their landing sites for evidence in rocks and soils about whether those areas ever had environments that were watery and possibly suitable for sustaining life.

Scientists had hoped for a specific landing site where they could examine both the surface layer that is rich in hematite and an underlying geological feature of light colored layered rock.

The small crater where Opportunity landed appears to have exposures of both, with soil that could be the hematite unit and an exposed outcropping of the lighter rock layer.

"If it got any better, I couldn't stand it," said Dr. Doug Ming, rover science team member from NASA Johnson Space Center, Houston.

With the instruments on the rover and just the rocks and soil within the small crater, Opportunity should be allow scientists to determine which of several theories about the region's past environment is right, he said. Those theories include that the hematite may have formed in a long lasting lake or in a volcanic environment.

An even bigger crater, which could provide access to deeper layers of the planet for more clues to its past, lies nearby. Images taken by a camera on the bottom of the lander during Opportunity's final descent show a crater about 150 meters (about 500 feet) across likely to be within about one kilometer or half mile of the landing site, said Dr. Andrew Johnson of the Jet Propulsion Lab.

In the coming weeks and months Opportunity is going to explore its immediate environment, said Squyers.

After driving off the lander, the rover will first examine the soil right next to the lander, then drive to the outcrop of layered rocks and spend considerable time examining it. Then the rover may climb out of the small crater, take a look around, and head for the bigger crater.

Artist's concept of one of the Mars Exploration Rovers (Image courtesy NASA)

Mars may be going through a period of climate change, new findings from the Odyssey orbiter suggest NASA scientists said in December 2003.

Odyssey has been mapping the distribution of materials on and near Mars’ surface since early 2002, nearly a full Martian annual cycle. Besides tracking seasonal changes, such as the advance and retreat of polar dry ice, the orbiter is returning evidence of patterns over a longer timeframe.

Dr. William Feldman of Los Alamos National Laboratory, New Mexico is the lead scientist for an Odyssey instrument that assesses water content indirectly through measurements of neutron emissions.

He says the amount of frozen water near the surface in some relatively warm low latitude regions on both sides of Mars' equator appears too great to be in equilibrium with the atmosphere under current climatic conditions, said

"One explanation could be that Mars is just coming out of an ice age," Feldman said. "In some low-latitude areas, the ice has already dissipated. In others, that process is slower and hasn't reached an equilibrium yet. Those areas are like the patches of snow you sometimes see persisting in protected spots long after the last snowfall of the winter."

Frozen water makes up as much as 10 percent of the top meter (39 inches) of surface material in some regions close to the equator. Dust deposits may be covering and insulating the lingering ice, Feldman said.

"Odyssey is giving us indications of recent global climate change in Mars," said Dr. Jeffrey Plaut, project scientist for the mission at NASA's Jet Propulsion Laboratory.

An with possible human travel to Mars in mind, an instrument on board the Odyssy used for monitoring the radiation environment on Mars shows the level of radiation hazard that Mars bound astronauts might face, including levels during a period of unusually intense solar activity, said Dr. Cary Zeitlin of the National Space Biomedical Research Institute, Houston.