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A.J.S. RaylJanuary 17, 2004

Spirit Extends Arm and Takes First Close-Up Images of Martian Soil

Joins Mars Express in First Coordinated Observation of Mars' Atmosphere

Spirit has extended her robotic arm for the first time to examine a patch of fine-grained Martian soil, and joined forces with the European Space Agency's Mars Express to successfully conduct the first-ever, international, coordinated observation of the planet's atmosphere.

The two accomplishments represent two more 'firsts' in what is becoming a long list of 'firsts' for the robot that captured the world's attention after bouncing to a near-perfect landing January 3 in Gusev Crater.

On Sol 13, "[w]e took the first microscopic images of another planet . . . we also conducted the first coordinated observations -- as Spirit looked up and Mars Express looked down," said mission manager Mark Adler at the daily news briefing yesterday. In addition, the team tested the Rock Abrasion Tool, known as the RAT, "and it checked out great," Adler said.

The robot field geologist's arm is about the same size as a human arm, with the same level of dexterity and comparable shoulder, elbow, and wrist joints. It is "one of the most dexterous and capable robotic devices ever flown in space," pointed out Eric Baumgartner, lead engineer for the instrument, which also goes by the name "instrument deployment device" or, simply, IDD.

"[The arm] has what we call five degrees of freedom -- five joints that we use to move the arm through its paces and it can move in both in azimuth and elevation," Baumgartner. "The turret is used to rotate the four instruments that are on the end of the arm -- the microscopic imager, the Mössbauer Spectrometer, Alpha Particle X-ray Spectrometer (APXS), and the rock abrasion tool (RAT). On Sol 13, lucky 13, we performed our first deployment of the IDD. . . and Spirit took the first picture of [her] own arm from the front hazard avoidance cameras. In short order, you will see some of the wonderful science this arm can enable for us by taking some close up images of soil and figuring out the chemistry and elemental composition of the rocks and soils within Gusev Crater."

The microscopic imager -- known simply as the MI by the scientists -- can show features as small as the width of a human hair. "[It] was designed to emulate a geologist's hand lens -- which is only appropriate because this is the first robotic field geologist on Mars -- and it will be very useful in understanding the geology of this surface," explained Ken Herkenhoff, lead scientist for the microscopic imagers on Spirit and Opportunity, and a member of the U.S. Geological Survey Astrogeology Team, based in Flagstaff, Ariz. "We got some great images in our first day using the microscopic imager . . . the highest resolution by far that we've ever seen."

While analysis of yesterday'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. "My own personal view is that this is an agglomerate of dust particles in the surface of Mars, perhaps 'cemented' together and it may be same material we saw earlier that was displaced by the airbags and pulled off the less 'cemented' surface down below," he added, referring to an area that they previously dubbed the Magic Carpet.

Meanwhile, ESA's Mars Express flew directly over the site late Thursday night PST at an altitude of about 186 miles or 300 kilometers and looked down with its High Resolution Stereo Camera and three spectrometers -- the OMEGA, designed to identify minerals in infrared and visible wavelengths, and the Planetary Fourier Spectrometer (PFS) and SPICAM for studying atmospheric circulation and composition. At the same time, Spirit was commanded to look up with her panoramic camera and an infrared spectrometer.

Mars Express' measurements are most sensitive for the upper atmosphere; whereas Spirit's measurements are most sensitive to the lower portion of the atmosphere. Together, the measurements taken from above and below at the same time will give scientists the ability to more accurately determine the dynamics of the Martian atmosphere. The mission team confirmed yesterday that the data from this first-of-its-kind international experiment had been acquired, but said that it will take some time before the results are known.

Back on Mars, even Spirit's tracks are providing new insight about the Martian surface in Gusev Crater. Details visible in images of the tracks from the rover's first drive, in fact, are already giving the science team information about the soil's physical properties.

"Rover tracks are great," noted science team member Rob Sullivan of Cornell University. "For one thing, they mean we're on the surface of Mars . . . [and] we look at them for engineering reasons and for science reasons." Sullivan pointed out that the first tracks show that the wheels did not sink into the surface too deep for driving and that the soil is made up of very small particles that provide a finely detailed imprint of the wheels.

The RAT, which passed its checkout with flying colors, will be put to use in the days to come as Spirit is directed to rove off to a selected rock. Before heading out, however, Spirit will rotate her turret of tools this weekend and "utilize each of the instruments on the arm," said Jessica Collisson, mission flight director. After a spot check of data, the team will command Spirit to pull out the Mössbauer spectrometer and -- for the first time -- reach out and touch the Martian soil.

"That activity will be our first contact with the soil," Collisson said. "We will actually take the Mössbauer instrument and touch it down onto the soil. We have contact switches on the face of the instrument, which we will use to confirm that we have made contact with the soil, and we'll let that instrument run for about four hours."

Provided that goes as planned, they will then command Spirit to retract the Mössbauer rotate the APXS out. "We will put that a few millimeters above the surface and we will activate the instrument to perform an integration overnight and operate this instrument for about 20 hours," said Collisson. Spirit will be asleep, "but we have the capability to keep the instrument on overnight," she explained. Both the Mössbauer and the APXS have this feature."

On Sunday, the team will retract the arm and close the APXS doors by rotating the turret. "We will restow the doors and run another integration and evaluate in the morning [Gusev time] and we'll leave the afternoon open for other activities," offered Collisson. While the Mössbauer and the APXS are in operation during the Martian daytime, "we will continue to do remote sensing activities," she added.

The mission team also plans to actuate the High Gain Antenna (HGA) this weekend, using it for both morning and afternoon transmissions of data.

"Now that we're on the surface, we are understanding what it means to be out there and how to operate the vehicle out there," Collisson summed up. "And we're looking forward to using the instrument deployment device and driving."

Read more: Spirit, mission status, Mars Express, Mars Exploration Rovers, Mars

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Salley Rayl
A.J.S. Rayl

Contributing Editor for The Planetary Society
Read more articles by A.J.S. Rayl

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