artist's concept of Mars Express; image credit: ESA J-L Atteleyn
Americans are participating in several ways in the European Space Agency's first mission to Mars, launched today from Baikonur, Kazakhstan.

The mission, Mars Express, will reach the red planet on Dec. 27 then examine it both from an orbiter with seven instruments and on the surface with a lander named Beagle 2. The orbiter will point ground-penetrating radar at Mars for the first time, probing for evidence of underground water. Beagle 2 will conduct biochemical and geological tests at a different site than the two areas where NASA's Mars Exploration Rovers will land in January 2004.

"The exploration of Mars is an international adventure," said Dr. Cathy Weitz at NASA Headquarters, Washington, D.C. "Our rover missions have key participants in Europe, and there are U.S. scientists on the teams for every instrument on Mars Express." Weitz serves dual coordinating roles as project scientist for NASA's participation in Mars Express and as program scientist for the Mars Exploration Rovers.

"This year's European and NASA missions to Mars truly complement each other in the added understanding they may give us about the present and past environments on that planet," said Dr. Jim Garvin, NASA's lead scientist for Mars exploration.

U.S. roles in Mars Express include navigational support from NASA's Jet Propulsion Laboratory, Pasadena, Calif., and communication support from the JPL-managed Deep Space Network, which operates antenna stations in California, Spain and Australia.

NASA supplied major components for the orbiter's radar experiment. "We have very little information about the crust of Mars more than about a meter below the surface, but with this instrument we hope to probe as deep as 5 kilometers" (3 miles), said JPL's Dr. Jeffrey Plaut, who, as co-principal investigator for the instrument, collaborates closely with Prof. Giovanni Picardi, principal investigator at the Universita di Roma in Rome, Italy.

"With the radar, we will try to detect boundaries between layers of different types of material," Plaut said. "If there is a boundary between a rock-ice mixture at the surface and a rock-water mixture at depth, it will reflect the radio waves and we hope to detect it. We'll be looking for aquifers -- subsurface reservoirs of liquid water -- but nobody really knows whether Mars has them."

The radar instrument, named the Mars Advanced Radar for Subsurface and Ionospheric Sounding, might also detect other types of layer boundaries, such as between sediments and underlying volcanic rock, or between the polar ice caps and underlying liquid water. This type of instrument, carried by aircraft, has detected vast lakes under polar icecaps on Earth. It has not been used on another planet, though a similar instrument flew on an Apollo mission, said Richard Horttor, project manager for NASA's roles in Mars Express.

Of the instrument's NASA-funded components, the University of Iowa, Iowa City, built the transmitter, JPL built the receiver, and Astro Aerospace, Carpinteria, Calif., built the 40-meter (131-foot) antenna. Italy provided the instrument's digital processing system and software, and integrated the parts together.

One major question about Mars, and about instability of a planet's environment, is what became of the water that once apparently flowed in abundance on Mars' surface. NASA's Mars Odyssey spacecraft now orbiting Mars has located ice mixed into the top meter (about 3 feet) of Mars surface. Theories differ as to how much more water -- frozen or melted -- lies deeper and how much may have dissipated from the planet's upper atmosphere. Mars Express will investigate the second possibility as well as the first. The radar instrument will examine the structure and variability of the ionosphere -- the atmosphere's top layer. Other instruments will study atmospheric chemistry and structure, and the interaction of the ionosphere with the solar wind of charged particles speeding outward from the Sun.

Additional instruments on the orbiter include a high-resolution stereo color camera and an infrared mineralogical mapping spectrometer. The Beagle 2 lander will look for chemical signs of life on Mars and use a mechanical "mole" to dig up samples from as far as 1.5 meters (nearly 5 feet) away from the lander, among other experiments. Cooperation between American and European Mars missions extends to plans for using Mars Odyssey to relay communications between Beagle 2 and Earth when Mars Express is not in good position to do so. The Mars Exploration Rovers will use Mars Express as a relay at least once as a demonstration for even broader international interdependence in future exploration of Mars.

Information is available online about Mars Express at and at, about Mars Exploration Rovers at, and about NASA at Mars Express is managed by the 15-nation European Space Agency's science and technology center at Noordwijk in the Netherlands. JPL, a division of California Institute of Technology in Pasadena manages Mars Odyssey, the Mars Exploration Rover missions, and NASA's participation in Mars Express for NASA's Office of Space Science, Washington, D.C.

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