PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. (818) 354-5011
                                                                                                
Contact: Mary A. Hardin

FOR IMMEDIATE RELEASE                                                March 23, 1993


       The construction phase of the international Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) mission has been completed and the radar system is now undergoing compatibility testing at NASA's Jet Propulsion Laboratory in preparation for launch.

       The U.S. SIR-C and the German-Italian X-SAR will fly aboard the space shuttle Atlantis in April 1994 as part of the first Space Radar Laboratory (SRL-1).

       "We have now completed the construction of a radar system that represents a new generation of spaceborne remote sensing radars," said Michael Sander, the JPL SIR-C mission manager. "This radar is a major step forward for Earth observations."

       A useful feature of imaging radar, also called synthetic aperture radar (SAR), is its ability to collect data over virtually any region, regardless of weather or sunlight conditions. The radar waves can penetrate clouds, and under certain conditions the radar can also see through vegetation, ice and dry sand.

       "In many cases, radar is the only way scientists can explore inaccessible regions of the Earth's surface," said Dr. Diane Evans, JPL SIR-C project scientist. "In addition, the sensitivity of SAR to soil, snow and vegetation moisture provides information that is critical to our understanding of global change."

       The SIR-C/X-SAR mission is a major technical step forward in the evolution of spaceborne imaging radar. It is the first spaceborne radar system that will simultaneously acquire images at multiple wavelengths and polarizations.

       "Radars using several frequencies are to Earth observations what the transition from black and white to color pictures was to photography," said Dr. Manfred Wahl, X-SAR project manager.

       SIR-C, built by JPL and the Ball Aerospace Corp.'s Communications Systems Division for NASA, is a two-frequency radar including L-band (23-cm wavelength) and C-band (6-cm wavelength). SIR-C will have the capability to transmit and receive horizontally and vertically polarized waves at both frequencies.

       X-SAR is built by Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI). It is a single-polarization radar operating at X-band (3-cm wavelength).

       The SIR-C portion of the mission is sponsored by NASA's Office of Mission to Planet Earth.


#####

3/23/93 MAH
#1500