The Bundeswehr Strategic Reconnaisance Command controls Germany's five radar imaging satellites. The German Defense Ministry developed a constellation, called SAR-Lupe, of five X-band radar satellites. The first satellite was launched in December 2006. Whereas most other SAR satellites in operation or development rely on electronically scanned array antennae, SAR-Lupe features a parabolic reflector antenna. Consequently, pointing the radar beam requires maneuvering the satellite. The satellite’s developer, OHBSystem of Bremen, asserts that SAR-Lupe will produce images with better than 1-meter resolution. According to a published report, OHB-System is offering a satellite based on the SAR-Lupe design to other governments for 40 million euros (about $50 million).
SAR-Lupe is Germany's first satellite-based reconnaissance system. It consists of five identical small satellites and a ground segment. OHB-System AG developed the overall system as the principal contractor for the German government, leading a consortium of well-known European space companies. Thanks to the intelligent combination of existing technologies, SAR-Lupe is able to operate night and day independently of weather conditions, delivering up-to-date high-resolution images from virtually all regions of the world.
The award of the SAR-Lupe contract to the OHB-System-led syndicate was announced in December 2001. The first satellite was launched and successfully placed in its intended orbit in December 2006. Within the space of the following 16 months, a further four satellites were placed in orbit at an altitude of around 500 km and successfully put into operation. Delivery of the overall system was officially accepted by the customer, the German Federal Office of Equipment, Information technology and Utilization (BAAINBw), in September 2008. The system was handed over to the Strategy Reconnaissance Command of the German Federal Armed Forces in December 2008. This also marked the commencement of the ten year satellite operation contract entered into with OHB-System.
- Sar Lupe 1 is a German military satellite that was launched by a Cosmos-3M rocket from Plesetsk at 14:00 UT on 19 December 2006. The 720 kg (dry mass) craft carries a Synthetic Aperture Radar (SAR) for providing all-weather, one-meter resolution images anywhere in the world. The mission is a German contribution to the joint Franco-German undertaking for mutual exchange of reconnaissance information.
- SAR Lupe 2 is a German military reconnaissance craft that was launched by a Kosmos 3M rocket from Plesetsk cosmodrome at 19:39 UT on 02 July 2007. The 770 kg craft carries a large Synthetic Aperture Radar (SAR) to provide 1-m resolution images. It is the second of five such craft that will eventually comprise the SAR Lupe fleet.
- Sar Lupe 3 is a German military radar reconnaissance craft that was launched by a Kosmos-3M rocket from Plesetsk on 01 November 2007. The 720 kg craft carries a X-band and S-band transmitters to provide one-meter resolution images. It is the third of an eventual five-craft constellation.
- SAR-Lupe 4 is a German military Synthetic Aperture Radar that was launched by a Kosmos 3-M rocket from Plesetsk at 15:15 UT on 27 March 2008. The 770 kg craft is the fourth of a five-craft fleet, each providing images at one-meter resolution, that will be shared with the French military.
- Sar Lupe 5 is a German military, Synthetic Aperture Radar satellite that was launched by a Kosmos 3M rocket from Plesetsk at 02:40 UT on 22 July 2008. The radar operates at an X-band frequency to provide images at one-meter resolution. The initial orbital parameters were period 94.3 min, apogee 501 km, perigee 470 km, and inclination 98.2°.
With SAR-Lupe, OHB-System proved that it was able to develop, build and launch satellite constellations featuring world-class technology. In addition, it demonstrated that it was a reliable partner as it managed to complete the project valued at EUR 320 million within the budget and on schedule.
In designing radar antennae for Earth-imaging satellites, two major options exist: active electronically steered arrays (AESAs) or reflector antennae. Most recent or planned civilian SAR satellites employ AESA designs. Those arrays consist of a matrix of transmit/receive modules; differences in timing between the signals at each module are used to form and steer the radar beam. However, some satellites, such as the German Defense Ministry’s SAR-Lupe constellation (which had its first launch in December 2006), use a conventional reflector antenna. The biggest advantage of an AESA design is the ability to steer the radar beam electronically. AESA antennae are also helpful for canceling clutter and countering electronic jamming. Conversely, a reflector antenna is generally lighter and less expensive than an AESA.
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