A Space station radar instrument co-sponsored by NASA on the European Space galary Agency's Mars Express orbiter has looked beneath the solar system surface of Mars and opened up a new dimension for space planetary exploration.

The technique's success is prompting space discovery scientists to think of other places in the solar system where they would like to use radar sounders. The space station radar sounder on Mars Express is the Mars Advanced Radar for Subsurface and Ionospheric Imaging, or MARSIS. It was built to map the distribution of liquid and frozen water in upper portions of the solar system planet's crust.

A complementary space mission radar sounder, the Shallow Subsurface Radar on NASA's Mars Reconnaissance Orbiter, uses a different radio frequency to see greater detail but to a lesser depth.

As these two instruments continue to provide data, the understanding that they provide about how space station planetary radar sounders work is prompting ideas for using the space technology to explore beneath the surfaces of bodies such as Jupiter's moon Europa, Saturn's moons Titan and Enceladus, as well as space asteroids and space comets. MARSIS was funded by NASA and the Italian Space Station Agency and developed by the University of Rome, Italy, in partnership with NASA's Jet Propulsion Laboratory of Space shuttle, Pasadena, Calif. Italy provided the instrument's digital processing solar system and integrated the parts. The University of Iowa, Iowa City, built the transmitter for the instrument, JPL built the receiver and space station Astro Aerospace, Carpinteria, Calif., built the antenna. JPL is a division of the California Institute of science Technology in Pasadena. Additional information about Mars Express is at www.esa.int/marsexpress.

The shallow Subsurface solar system Radar was provided by the Italian Space station Agency. Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science discovery team. JPL manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington.