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Problems to Delay Spirit Rover's Trek on Mars

Posted on: Wednesday, 7 January 2004, 06:00 CST

By ANDREW BRIDGES

PASADENA, Calif. (AP) -- The air bags that cushioned the landing of the Mars rover are obstructing the vehicle's path and will delay the start of its trek across the planet's rust-colored surface, NASA said Wednesday.

Further complicating the mission, new images from the Mars rover suggest its landing site is not the pristine dry lake bed that scientists originally had hoped. That means the rover's hunt for evidence that Mars was once a wetter place conducive to life might be more difficult than expected.

The earliest the six-wheeled Spirit rover will roll off the spacecraft that brought it to Mars is Jan. 14, or about three days later than originally planned, NASA said. Further delays of one or two days are possible.

"We are champing at the bit to get this puppy off the lander and get driving," said Art Thompson, a robotics engineer on the mission.

Two sections of the now-deflated air bags partially block the ramp that the rover is supposed to use. Engineers will work to further retract parts of the bags before Spirit begins its expedition to dig up rocks and soil.

"As soon as we get that air bag out of the way, we're good to go," said Arthur Amador, mission manager for Spirit's fifth day on Mars.

If scientists are unable to clear the path, Spirit can roll down either of two other ramps. Those maneuvers would require the rover to perform a robotic pirouette, however, to ensure it faced the right direction.

Scientists picked Spirit's landing site inside Gusev Crater because they believed the depression once contained a brimming lake - the type of place that may have been hospitable to life. If that was the case, Spirit should be seeing a flat plain rich in fine-grain sediment, said Ray Arvidson, the mission's deputy principal scientist.

"That's not what we're looking at," Arvidson said.

Spirit's first look suggests if the landing site was ever a lake bed, it has been significantly altered by other geologic events. What they might have been remains the subject of intense debate.

Arvidson said a volcanic eruption could have buried the dry lake bed with lava, which was then fragmented by blows from asteroids or comets. Later, deposits carried by wind, water or even ice glaciers might have further buried the area with the rocky debris that Spirit's cameras show in crisp detail.

"The question is going to be how far we have to go and what we have to do to find a smoking gun" that would prove Mars once was a wetter world, Arvidson said.

The $820 million project includes a second, identical rover, Opportunity, which is scheduled to arrive on Mars on Jan. 24.

In a separate, European mission, the British-built Beagle 2 has not been heard from since its mother ship set it loose toward the Red Planet in mid-December. Another attempt to reach the probe failed to pick up a signal Wednesday.

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:

This image, taken on January 7, 2004, shows the martian terrain in 3-D. The Mars Exploration Rover Spirit captured the image with its two high-resolution stereo panoramic cameras. Image credit: NASA/JPL/Cornell University

This is the first color image of Mars taken by the panoramic camera on the Mars Exploration Rover Spirit. It is the highest resolution image ever taken on the surface of another planet. Image credit: NASA/JPL/Cornell University

-- 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.

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