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Shuttle Radar Topography Mission



The SRTM main antenna was positioned in the cargo bay of Space Shuttle Endeavour. It contained two types of radar panels, C-band and X-band, and both transmitted and received radar signals.

Schematic of main antenna

The main antenna actually consisted of two antennas and the avionics that computed the position of the antennas. Each antenna was made up of special panels that could transmit and receive radar signals.
Photo of main antenna
SRTM main antenna standing up on end. C-band panels are on the bottom, X-band panels are hinged over the top. Avionics electronics package is positioned at the top middle. SRTM astronaut crew is in the foreground.
C-band Radar Antenna

One antenna was called the C-band antenna and could transmit and receive radar wavelenths that are 5.6 centimeters long. During the mission the C-band radar, with a swath width (width of the radar beam on Earth's surface) of 225 kilometers, scanned about 80% of the land surface of the Earth.

The C-band data are being processed at the Jet Propulsion Laboratory to make a near-global topographic map of the Earth.

X-band Radar Antenna

The other antenna was the X-band antenna. This antenna could transmit and receive radar wavelenths that are 3 centimeters long. The X-band radar, with a swath width of 50 kilometers, will produce topographic maps at a somewhat higher resolution than the C-band data, but will not have near-global coverage.

The X-band data are being processed and distributed by DLR (Deutsches Zentrum fur Luft- und Raumfahrt), the German Aerospace Center.

Forward end of main antenna at KSC
Forward end of main antenna in the Launch Package Integration Stand at KSC. This is the view the astronauts saw from inside the Shuttle.

In case you're wondering...

If you're wondering what those big panels are between the C-band and X-band panels, they are L-Band radar panels. The L-Band panels used on the 1994 missions of the Shuttle Imaging Radar (SIR-C) but were not needed for the SRTM mission.