Perspectives on Worldwide Spaceborne Radar Programs

Radar technology and techniques were originally developed for land-based, maritime, and airborne applications. Spaceborne radar systems development began in the 1960s in the USSR for military purposes, and in the 1970s in the United States for civilian scientific purposes. NASA launched the SeaSAT satellite in 1978, carrying a synthetic aperture radar, a radar altimeter, a radar scatterometer, and a radiometer, ushering in the modern era of spaceborne radar observations. NASA embarked on a shuttle-based space radar program in the 1980s that was geared to advancing space radar technology and demonstrating scientific utility of multi-parameter synthetic aperture radar, culminating in the Shuttle Imaging Radar-C flights in 1994. With the launch of the European Space Agency ERS satellite and the Japanese JERS satellite in 1992, and the Canadian Radarsat satellite in 1995, international systems have had a persistent orbiting radar presence in space around the Earth, replenished with new systems with increasing emphasis on dual use capabilities, while the US has fielded only one Earth orbiting space radar system for a 10-day period in 2000, the Shuttle Radar Topography Mission. The US program has evolved differently, with emphasis on mapping SARs for the planet Venus and Saturn´s moon Titan, and a series of targeted scientific platforms focusing on Earth system and climate studies: TOPEX altimetry and follow-ons for ocean topography, QuikScat scatterometer for global winds, and TRMM and Cloudsat for precipitation and cloud water content. Radar programs worldwide are flourishing as the technology advances and new scientific uses and applications are generated from the abundant globally acquired data from international systems. Questions of security and global competition are now complicating the development of highly capable systems, such as the SAR systems required for persistent surveillance in both the military and scientific arenas.