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Mars Odyssey images: 'A lot of ice'

Thermal imaging and gamma ray spectrometry operative

Soil enriched with hydrogen is indicated by the deep blue coloration in this image of Mars made during the first week of the Odyssey spacecraft's mapping operations.
Soil enriched with hydrogen is indicated by the deep blue coloration in this image of Mars made during the first week of the Odyssey spacecraft's mapping operations.  


By Porter Anderson
CNN

(CNN) -- Declaring it a "red letter day for Mars exploration," NASA's Michael Meyer opened a briefing Friday in which scientists said the first data received from the Mars Odyssey spacecraft suggests that there are significant amounts of hydrogen -- related to ice -- in the south polar region of the planet.

Gamma ray spectrometry investigator William Boynton said, "The signal we've been getting loud and clear is that there's a lot of ice on Mars. ... All the way from the south pole up to about -60 degrees latitude."

Odyssey's mission is to map the surface of Mars in such a way as to show up "minerals that may have been formed in water," one scientist said. "Those will act as beacons of the places we want to go and study Mars in detail with future rovers, landers and sample returns."

The craft was launched on April 7 of last year and arrived at Mars on October 24. Its principal mission is designed to run through August 2004.

Odyssey carries three key sets of instruments.

  • THEMIS, the Thermal Emission Imaging System, is a type of a camera that takes "pictures" by using infrared measurements of temperatures. It's operative now and has produced first images this week.
  • GRS, the Gamma Ray Spectrometer, is designed to determine the presence of 20 chemical elements on the surface. Gamma rays are produced when cosmic rays hit the surface of the planet, throwing off neutrons. The spectrometer is working now, and an arm is to extend its equipment away from the orbiter soon to enhance the purity of its readings.
  • MARIE, the Mars Radiation Environment Experiment -- which was powered down in August because it stopped communicating -- had registered a daily level of radiation on the trip to Mars that was more than twice that experienced by astronauts on the international space station.
  • 'Incredible diversity'

    This first high-resolution color infrared image taken of Mars shows the region known as Terra Sirenum.  Color infrared images reveal features of the planet's surface composition.
    This first high-resolution color infrared image taken of Mars shows the region known as Terra Sirenum. Color infrared images reveal features of the planet's surface composition.  

    Phillip Christensen, principal investigator for the orbiter's camera system -- and a faculty member at Arizona State University in Tempe -- joined the briefing in Pasadena, California, to describe some of the infrared imagery produced by THEMIS.

    In pictures of impact craters, Christensen said, THEMIS is producing a way for scientists to "see" areas of rock and sand according to how they heat and cool.

    "Mars turns out to have ... an incredible diversity of land forms, of structures," Christensen said. "We see craters, we see mesas, we see rocky places" and "halos" around craters that are made of rock thrown out of the centers during impact "thousands if not millions of years ago."

    What Christensen calls the most novel aspect of THEMIS' capabilities is the ability to take photos "in the dead of night" by registering temperature differences. The coldest regions under surveillance, Christensen said, register about -150 degrees Fahrenheit, an extreme that doesn't prevent THEMIS from getting images.

    In one picture, he described a region of "disrupted terrain" that may have been produced by the "rapid removal of underground water." Using 10 filters, THEMIS can generate colored images.

    Jim Garvin, Lead scientist of the Mars Exploration Program at NASA, said that after one week of mapping observations, "the preliminary assessment of the gamma-ray spectrometer data indicates the likely presence of hydrogen in the upper few feet of the martian surface."

    Getting there

    Odyssey has traveled 292 million miles (470 million kilometers) to reach Mars. "We hit our target altitude within 750 meters," or 820 yards, Garvin said.

    A drawing of Mars Odyssey
    A drawing of Mars Odyssey  

    A 20-minute burn allowed the craft to be captured by Mars' gravity and put into an 18-and-a-half-hour orbit of the red planet. In 75 more days of 340 "drag passes" -- each of which slowed down Odyssey a bit -- it was finally placed in a two-hour circular orbit of Mars.

    The vehicle's high-gain antenna was put into use, and then on Monday, the science instruments on Odyssey were trained on the surface of Mars.

    "Today we have a very well-operating spacecraft," Garvin said. "The main consumable, propellent, is ample for both our prime mission and a good healthy extended mission beyond that." Garvin pointed out that eventually Odyssey may support Mars rover missions, in part by characterizing potential landing sites.

    Stephen Saunders, a Johnson Propulsion Laboratory scientist with the Odyssey project, said that on Mars -- where years are twice as long as Earth's -- temperatures in both hemispheres are rising to just above freezing in the daytime. It's the equivalent of very early spring in the northern part of the planet. In the south, fall is nearing and the polar cap will soon go into a monthlong "winter night."



     
     
     
     


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