Two German radar satellites are tracing a helix across the sky just a few hundred feet of each other in a mission expected to produce the most detailed 3D map of the Earth's entire surface. DLR, the German space agency, hopes to finish testing and begin acquiring data from TanDEM-X and TerraSAR-X by Christmas. The improved 3D and accuracy is expected to aid aircraft navigation, pinpoint flood-prone areas and lead to more realistic terrain for the virtual worlds of flight simulators.
The helical flight profile is thought to be unique in civil space history, and should ensure the two satellites never bump into each other. The digital elevation model of the Earth's surface should be available in 2014. The radars constantly bounce microwave pulses off the ground and sea surface. By timing how long the signal takes to make the return trip, the instruments can determine differences in height. As the orbits are very slightly offset, a kind of stereo vision is achieved. The data will pin down variation in height across the globe to an accuracy of better than six feet. Geology and hydrology are among the sciences that will benefit from the improved accuracy. The BBC reports that the venture is a public-private partnership. The German space agency owns the hardware; EADS Astrium builds it; and Infoterra GmbH has exclusive rights to commercialize the data. Responsibility for controlling the spacecraft falls to the German Space Operations Centre (GSOC) in Oberpfaffenhofen. TerraSAR-X was launched in 2007. TanDEM-X was put in space in June, since when it has been brought closer and closer to its travel companion. (WRITTEN Oct 2010) Estimated date
Date written/update: 2010-12-25