NASA Jet Propulsion Laboratory, California Institute of Technology

After months of testing and years of planning, the antenna that makes up the joint U.S./German/Italian Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) has arrived at NASA's Kennedy Space Center in Florida where it will be integrated into the space shuttle.

SIR-C/X-SAR will fly aboard the space shuttle Endeavour in April 1994 as part of the Space Radar Laboratory (SRL). This will be the first of at least two planned flights which will allow scientists to make highly detailed studies of Earth's surface on a global scale. By comparing the results from the flights, scientists will gain important new information about global change and seasonal variations.

The SIR-C/X-SAR antenna is the most massive piece of flight hardware ever built at JPL.

"A lot of people have worked very, very hard to put together a powerful new instrument for science. The shipment of this antenna to the Cape is a major milestone in the history of the SIR-C program," said Michael Sander, SIR-C project manager at JPL.

A synthetic aperture radar transmits pulses of microwave energy toward Earth and collects the energy that is scattered back to the antenna. The motion of the shuttle is used to "synthesize" an antenna (the aperture) that is much longer in length than the actual SIR-C/X-SAR antenna in the shuttle. A longer antenna produces images of finer resolution.

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.

SIR-C, built by JPL and the Ball Communications Systems Division for NASA, is a two-frequency radar including L-band (23cm 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).

SIR-C is managed by JPL for NASA's Office of Mission to Planet Earth.

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