Institut für Astronomie & Astrophysik

The (failed) ABRIXAS Mission

The small satellite 'ABRIXAS' (A BRoad-band Imaging X-ray All-sky Survey Satellite) was planned as a follow-up of the successful ROSAT-mission and was intended to perform the first complete survey of the sky with an imaging telescope in the X-ray energy range from 0.5- up to 10-keV. During its planned life-time of 3 years, ABRIXAS was expected to discover more than 10.000 new X-ray sources, mainly active galaxies above 2-keV. In the centres of these galaxies, persumably black holes convert gravitational energy into high energy radiation. Very often, like in our galaxy, the centres are covered by cloudes of gas and dust, which can be penetrated by high energy X-rays.

The scientific responsibility was with the Leibniz-Institut für Astrophysik Potsdam (AIP), the Max-Planck-Institut for Extraterrestrial Physics (MPE), and the Institute for Astronomy and Astrophysics of the University of Tübingen (IAAT). The German Space Agency - DARA - took over the project management. Main contractor for development, construction and launch of the satellite was the OHB-System GmbH, Bremen.

The X-ray optics system consisted of seven twentysevenfold nested Wolter-I mirror-modules with a focal length of 1.6 m, which were built by Carl Zeiss and tested at the X-ray test facility PANTER of MPE. The focal instrumentation was a novel pn-CCD X-ray detector having high efficency and a good spectral resolution. It was developed by MPE/IAAT. With respected to the scientific and technological achievments ABRIXAS was expected to have a pathfinder role for further X-ray missions.

The satellite was launched into an orbit of 580 km, 51 deg inclination with a COSMOS rocket from the Russian launch centre Kapustin Yar on April 28. 1999.

The mission finally failed due to a faulty satelite power system.

ABRIXAS Technical Data

Total mass: 550 kg
Payload Mass: Approx. 160 kg
Dimensions: Height 2500 mm
Width 1800 mm
Depth 1150 mm
Energy Supply: 2 battery packages
Solar Generator
Capacity: 200 W (average)
Board Computer: Transputer T 800/805 INMOS
Mass Memory: 64 Mbyte
Software: Parallel C, RTXC Real Time Kernel
Telemetry: S-Band, 500 kbps
Telecommand: S-Band, 4kbps
Redundancy: Parallel on-board electronic with cross coupling
Attitude Control: Magnetic, momentum wheel