Terrasar

TerraSAR-X is a German Earth observation satellite that uses an X-band SAR to provide high-quality topographic information for commercial and scientific applications. Launched 15 June 2007 aboard a Dnepr rocket from Baikonur, it produced preliminary imagery on June 19, 2007. Development was a joint project between the German Aerospace Center (who contributed 100 million euros to the project) and EADS Astrium (contributed 30 million euros). Infoterra holds the exclusive commercial exploitation rights.

The satellite works in the X-band (wavelength 31 mm, frequency 9.6 GHz) and is called therefore TerraSAR-X. The short wavelength makes the technical development a little more difficult but permits a high resolution of the digital radar images, up to 1 meter at the earth's surface.


TerraSAR X will exhibit some technical-industrial novelties. One of these innovations is a kind of zoom shot, with the dissolution and scanning field vice versa changeable in a 1:10 relationship, either a larger area to grasp or a small area with the highest possible resolution.

Furthermore the antenna can be aligned by electronics within an angle range so that the point of view is adjustable. Earlier radar satellites could radiate the antenna only in one direction.
TerraSAR X is 5 meters high, weighs about 1230 kg and circles the Earth in a nearly polar orbit at approximately 500 km altitude. With the adjustable angle radar sensor - along with other course refinements (precession by the earth flattening) - any place on earth can be observed preferentially within 1-3 days.
For a specific point on the earth's equator, TerraSAR X has a revisit cycle of 11 days. The revisit time decreases towards the poles, e.g. northern Europe has a revisit time of typically 3-4 days.

The ground operating mechanism and controls for the TerraSAR X is developed by the DLR in Oberpfaffenhofen. It consists of Mission Operating Equipment, the Payload Ground Segment and the Instrument Operation and Calibration Segment. At the base of the ground segment lies the German Space Operation Center (GSOC), the German Remote Sensing Datum Center (DFD) as well as Institutes for Methodology of Remote Sensing (MF) and the Institute for High-Frequency Engineering and Radar Systems (HR) which are all part of the DLR.