Radar Range; February 1996; Scientific American Magazine; by Powell; 2 Page(s)

There is more to these pictures of the earth than meets the eye--literally--because they were taken with radar, not visible light. As part of the ambitious "Mission to Planet Earth" project, the National Aeronautics and Space Administration, in conjunction with the Italian and German governments, has created a sophisticated radar system that rides on board the space shuttle and compiles detailed maps of the earth below. These recently processed images showcase the system¿s ability to reveal subtle geologic and environmental details that are difficult, if not impossible, to detect from the ground. Radar has no inherent color, so researchers assigned arbitrary hues to the various wavelengths and degrees of polarization of the radar; colors were selected to highlight certain details and to make the images aesthetically pleasing.

A radar map of the region around Pishan, a town in northwest China that lies along the ancient Silk Route, captures the changing climate of the region (below). The bright lavender, fernlike branches that cut across the center of the image represent ancient gravel deposits, known as alluvial fans, that washed down from the surrounding mountains during an earlier time when the area received much more rainfall. Modern erosion features show up as broad, lavender triangular features located above the older fans. A massive irrigation project overcomes the current, dry climate, creating the vegetated space shuttle with related radar views taken from a NASA DC-8 aircraft to evaluate the environmental effects of the floods that ravaged the Mississippi Valley in 1993.