Americans are participating 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

http://sci.esa.int/home/marsexpress

and at
http://mars.jpl.nasa.gov/express ,

about the radar experiment at

http://www.marsis.com http://www.marsis.com/ ,

about Mars Exploration Rovers at

http://mars.jpl.nasa.gov/mer ,

and about NASA at
http://www.nasa.gov .

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.