- Original Caption Released with Image: This three-frequency
space radar image of south-central Egypt demonstrates the unique
capability of imaging radar to penetrate thin sand cover in arid
regions to reveal hidden details below the surface. Nearly all
of the structures seen in this image are invisible to the naked
eye and to conventional optical satellite sensors. Features
appear in various colors because the three separate radar
wavelengths are able to penetrate the sand to different depths.
Areas that appear red or orange are places that can be seen only
by the longest wavelength, L-band, and they are the deepest of
the buried structures. Field studies in this area indicate
L-band can penetrate as much as 2 meters (6.5 feet) of very dry
sand to image buried rock structures. Ancient drainage channels
at the bottom of the image are filled with sand more than 2
meters (6.5 feet) thick and therefore appear dark because the
radar waves cannot penetrate them. The fractured orange areas at
the top of the image a