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NASA's Spirit Reaches for a Closer Look

Posted on: Friday, 16 January 2004, 06:00 CST

Jet Propulsion Lab -- NASA's Spirit rover reached out with its versatile robotic arm early today and examined a patch of fine-grained martian soil with a microscope at the end of the arm.

"We made our first use of the arm and took the first microscopic image of the surface of another planet," said Dr. Mark Adler, Spirit mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The rover's microscopic imager, one of four tools on a turret at the end of the arm, serves as the functional equivalent of a field geologist's hand lens for examining structural details of rocks and soils.

"I'm elated and relieved at how well things are going. We got some great images in our first day of using the microscopic imager on Mars," said Dr. Ken Herkenhoff of the U.S. Geological Survey Astrogeology Team, Flagstaff, Ariz. Herkenhoff is the lead scientist for the microscopic imagers on Spirit and on Spirit's twin Mars Exploration Rover, Opportunity.

The microscope can show features as small as the width of a human hair. While analysis of today's images from the instrument has barely begun, Herkenhoff said his first impression is that some of the tiny particles appear to be stuck together.

Before driving to a selected rock early next week, Spirit will rotate the turret of tools to use two spectrometer instruments this weekend on the same patch of soil examined by the microsope, said Jessica Collisson, mission flight director. The Mössbauer Spectrometer identifies types of iron-bearing minerals. The Alpha Particle X-ray Spectrometer identifies the elements in rocks and soils.

The rover's arm is about the same size as a human arm, with comparable shoulder, elbow and wrist joints. It is "one of the most dextrous and capable robotic devices ever flown in space," said JPL's Dr. Eric Baumgartner, lead engineer for the robotic arm, which also goes by the name "instrument deployment device."

"Best of all," Baumgartner said, "this robotic arm sits on a rover, and a rover is meant to rove. Spirit will take this arm and the tremendous science package along with it, and reach out to investigate the surface."

The wheels Spirit travels on provide other ways to examine Mars' soil. Details visible in images of the wheel tracks from the rover's first drive onto the soil give information about the soil's physical properties.

"Rover tracks are great," said Dr. Rob Sullivan of Cornell University, Ithaca, N.Y., a member of the science team for Spirit and Opportunity. "For one thing, they mean we're on the surface of Mars! We look at them for engineering reasons and for science reasons." The first tracks show that the wheels did not sink too deep for driving and that the soil has very small particles that provide a finely detailed imprint of the wheels, he said.

Opportunity, equipped identically to Spirit, will arrive at Mars Jan. 25 (Universal Time and EST; 9:05 p.m. Jan. 24, PST). The amount of dust in the atmosphere over Opportunity's planned landing site has been declining in recent days, said JPL's Dr. Joy Crisp, project scientist for the Mars Exploration Rover Project.

Today, Spirit completes its 13th martian day, or "sol", at its landing site in Gusev Crater. Each sol lasts 39 minutes and 35 seconds longer than an Earth day. The rover project's goal is for Spirit and Opportunity to explore the areas around their landing sites for clues in the rocks and the soil about whether the past environments there were ever watery and possibly suitable for sustaining life.

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.

This overhead polar image was captured after the Mars Exploration Rover Spirit took a few baby rolls away from the spacecraft that bore it millions of miles to Mars. The empty lander, now named the Columbia Memorial Station, can be seen to the right of the rover. This image was taken by Spirit's navigation camera. Image Credit: NASA/JPL

This close-up look at a patch of martian soil is the sharpest image ever taken of another planet. The actual size of the patch is about 3 centimeters (1.2 inches) across. Image Credit: NASA/JPL/US Geological Survey

This image taken by the microscopic imager on the Mars Exploration Rover Spirit shows the powdery soil of Mars in 3-D. It is the sharpest look yet at the surface of another planet. Image Credit: NASA/JPL//US Geological Survey

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.

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