Why was the L-band antenna not used for SRTM?
The payload weighed too much; so the L-band panels had to be removed. Why were C-band X-band used? Why didn’t you use only one? I realize that two radar images have to be combined, but those two images are from the outboard and inboard antennas, I thought. Please elaborate on this. The X-band system was supplied by the German and Italian space agencies and was flown in 1994 aboard SIR-C/X-SAR. As a continuation of this international cooperation, NASA invited them to contribute a second antenna, to form an X-band single-pass interferometer. Unlike the C-band system, the X-band couldn’t steer its beam, so it couldn’t operate in ScanSAR mode and therefore couldn’t get full coverage of the earth. Its 50 kilometer swath offered nearly complete coverage at high latitudes, though. Because it doesn’t scan, the X-band system also had a little better vertical error- probably around 5 meters.