SAR-Lupe is Germany's first reconnaissance satellite system and is used for military purposes. SAR is an abbreviation for synthetic-aperture radar, and "Lupe" is German for magnifying glass. The SAR-Lupe program consists of five identical (770 kg) satellites, developed by the German aeronautics company OHB-System, which are controlled by a ground station responsible for controlling the system and analysing the retrieved data. A large data archive of images will be kept in a former Cold War bunker belonging to the Kommando Strategische Aufklärung (Strategic Reconnaissance Command) of the Bundeswehr. The total price of the satellites was over 250 million euros.
SAR-Lupe's "high-resolution" images can be acquired day or night through all weather conditions. The satellites are able to provide up-to-date imagery from almost all regions of the world.
The first satellite was launched from Plesetsk in Russia on 19 December 2006, about a year after the intended launch date; four more satellites were launched at roughly six-month intervals, and the entire system achieved full operational readiness on 22 July 2008. The constellation is planned for 10 years of operational life.
The five satellites operate in three 500-kilometre orbits in planes roughly 60° apart. They use an X-band radar with a 3-metre dish, providing a resolution of about 50 centimetres over a frame size of 5.5 km on a side ("spotlight mode", in which the satellite rotates to keep the dish pointed at a single target) or about 1 metre over a frame size of 8 km × 60 km ("stripmap mode", in which the satellite maintains a fixed orientation over the Earth, and the radar image is formed simply by the satellite's motion along its orbit). Response time for imaging of a given area is 10 hours or less. Thales Alenia Space provided the core of the synthetic-aperture radar sensors.
The SAR-Lupe satellites are the first German military satellites.
The testing of SAR-Lupe involved an inverse procedure, in which the satellite, mounted in a radome on Earth, was used to image the International Space Station, whose orbit is reasonably close to the one the satellite will eventually be in. One-metre resolution at the ISS was apparently achieved.
On 30 July 2002 a cooperation treaty between Germany and France was signed, under which the SAR-Lupe satellites and the French Helios optical reconnaissance satellite will operate jointly. Other EU countries have been invited to join as well, and Italy has shown considerable interest.
XSAR of SAR-Lupe is observing in X-band (center frequency of 9.65 GHz corresponding to a wavelength of 3.1 cm).
Prior to an image acquisition, the satellite rolls in an appropriate position and stabilizes its attitude. Then, the SAR image is acquired. After that, the satellite rolls back into its standby attitude and continues to charge its batteries, preparing itself for the next SAR image acquisition.
|Satellite||COSPAR||Date||Carrier rocket||Launch site||Launch status|
|SAR-Lupe-1||2006-060A||19 December 2006||Cosmos-3M||Plesetsk||Success|
|SAR-Lupe-2||2007-030A||2 July 2007||Cosmos-3M ||Plesetsk||Success|
|SAR-Lupe-3||2007-053A||1 November 2007||Cosmos-3M ||Plesetsk||Success|
|SAR-Lupe-4||2008-014A||27 March 2008||Cosmos-3M ||Plesetsk||Success|
|SAR-Lupe-5||2008-036A||22 July 2008||Cosmos-3M ||Plesetsk||Success|
A replacement of SAR-Lupe, called SARah, will be put into service from 2021. It will consist of 3 radar satellites and one optical satellite. The satellites of SARah will be bigger and more capable than those of SAR-Lupe. SARah-1, a phased-array-antenna satellite, and SARah-2 and -3, passive-antenna synthetic aperture radars, are planned to be launched on Falcon 9 sometime in 2021.