Mars Rovers May Struggle to Find Water Traces
By ANDREW BRIDGES
PASADENA, Calif. (AP) — NASA’s Spirit rover traveled 300 million miles to search for evidence that frozen, dry Mars was once a wetter planet capable of supporting life. But scientists now say their best chance for finding that evidence may be out of the robot’s range.
Spirit landed in Gusev Crater, a 95-mile-wide depression thought by some to have contained a lake in the ancient past, but it has turned out to be far from a pristine dry lake bed.
The broad depression appears to have been blanketed by volcanic debris and scoured by the wind, with the deposits of lake sediments that scientists had hoped to find either buried or erased by 4 billion years of vigorous geologic activity.
“Goodness knows what you might have stripped away,” said Mars scientist Maria Zuber, of the Massachusetts Institute of Technology.
That means Spirit might have to roam farther than NASA expected to find the evidence scientists seek. The most promising place appears to be in a group of hills that NASA is not even sure the rover can reach.
“It might take a bit of searching to find,” said Dave Des Marais, of NASA’s Ames Research Center in Mountain View and a member of the mission science team.
Scientists say the hills, which rise hundreds of feet above the martian plain, represent a far bigger slice of the planet’s history than the relatively shallow crater Spirit is visiting first.
But the hills are farther away than Spirit was designed to travel, even if the solar-powered rover outlasts its three-month lifetime. Still, mission engineers continue to calculate how much ground Spirit would have to cover to reach their slopes.
Scientists are also holding out hope that the rocks in Spirit’s more immediate surroundings could be the smoking gun. Examples would include any carbonate rocks, such as limestone, that form in water.
“Rocks are like little time capsules. They remember what formed them and the time that formed them,” Des Marais said.
Short of that, the closest evidence could be as close as 825 feet away, inside a crater that the air bag-swaddled Spirit nearly landed in when it bounced down on the planet two weeks ago.
As Spirit zigzags toward that depression, rolling dozens of yards a day, the robot geologist should come across older rocks. Once at the crater, scientists hope Spirit can reach the rim and peer down. The rover has nine cameras, including a microscopic imager, and a rock drill to examine the terrain.
Scientists hope to find the crater walls striped with horizontal layers of sedimentary rocks, which would suggest that Gusev once sloshed with water.
A second martian spacecraft, Opportunity, is on track to land Jan. 24 halfway around the planet from Spirit. Its landing site abounds in a mineral called gray hematite, which is associated with liquid water.
About the Mars Exploration Rover Mission
NASA’s twin robot geologists, the Mars Exploration Rovers, launched toward Mars on June 10 and July 7, 2003, in search of answers about the history of water on Mars. Spirit landed on January 3, and Opportunity is scheduled to land on January 24, 2004.
The Mars Exploration Rover mission is part of NASA’s Mars Exploration Program, a long-term effort of robotic exploration of the red planet.
Primary among the mission’s scientific goals is to search for and characterize a wide range of rocks and soils that hold clues to past water activity on Mars. The spacecraft are targeted to sites on opposite sides of Mars that appear to have been affected by liquid water in the past.
The landing sites are at Gusev Crater, a possible former lake in a giant impact crater, and Meridiani Planum, where mineral deposits (hematite) suggest Mars had a wet past.
After the airbag-protected landing craft settle onto the surface and open, the rovers will roll out to take panoramic images.
These will give scientists the information they need to select promising geological targets that will tell part of the story of water in Mars’ past. Then, the rovers will drive to those locations to perform on-site scientific investigations over the course of their 90-day mission.
These are the primary science instruments to be carried by the rovers:
– Panoramic Camera (Pancam): for determining the mineralogy, texture, and structure of the local terrain.
– Miniature Thermal Emission Spectrometer (Mini-TES): for identifying promising rocks and soils for closer examination and for determining the processes that formed Martian rocks. The instrument will also look skyward to provide temperature profiles of the Martian atmosphere.
– Mössbauer Spectrometer (MB): for close-up investigations of the mineralogy of iron-bearing rocks and soils.
– Alpha Particle X-Ray Spectrometer (APXS): for close-up analysis of the abundances of elements that make up rocks and soils.
– Magnets: for collecting magnetic dust particles. The Mössbauer Spectrometer and the Alpha Particle X-ray Spectrometer will analyze the particles collected and help determine the ratio of magnetic particles to non-magnetic particles. They will also analyze the composition of magnetic minerals in airborne dust and rocks that have been ground by the Rock Abrasion Tool.
– Microscopic Imager (MI): for obtaining close-up, high-resolution images of rocks and soils.
– Rock Abrasion Tool (RAT): for removing dusty and weathered rock surfaces and exposing fresh material for examination by instruments onboard.
A goal for the rover is to drive up to 40 meters (about 44 yards) in a single day, for a total of up to one 1 kilometer (about three-quarters of a mile).
Moving from place to place, the rovers will perform on-site geological investigations. Each rover is sort of the mechanical equivalent of a geologist walking the surface of Mars. The mast-mounted cameras are mounted 1.5 meters(5 feet) high and will provide 360-degree, stereoscopic, humanlike views of the terrain.
The robotic arm will be capable of movement in much the same way as a human arm with an elbow and wrist, and will place instruments directly up against rock and soil targets of interest.
In the mechanical “fist” of the arm is a microscopic camera that will serve the same purpose as a geologist’s handheld magnifying lens. The Rock Abrasion Tool serves the purpose of a geologist’s rock hammer to expose the insides of rocks.
—–
Follow every step of the Mars Exploration Rover Mission with RedNova. Click here to learn more…
—–
On the Net:
Mars Exploration Rover Mission
More science, space, and technology from RedNova
Copyright © 2003 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.
