Amateur satellite "MaxValier Sat" launches with µROSI
On the 23rd of June, the amateur satellite "MaxValier Sat" was successfully launched into an Earth orbit on an Indian rocket. On board: the miniature X-ray telescope μROSI, which was built by the Max Planck Institute for Extraterrestrial Physics in Garching. Intensive work had been carried out in South Tyrol, Munich and Bremen to get all instruments ready. The MaxValier satellite is a unique cooperation between academic research, the aerospace industry and the commercial schools in Bolzano and Merano. The aim of the mission is to provide a complete survey of the sky in soft X-rays – with the data being broadcast to amateur astronomers - as well as observing the Earth’s upper atmosphere to discover an oxygen absorption line.
Based on the famous ROSAT satellite, the design of μROSI at the Max Planck Institute for Extraterrestrial Physics (MPE) presented some very special challenges due to its very small size. The mini telescope requires all components of a "real" telescope: A mirror module with 12 nested mirror shells, a detector module and control electronics, as well as a cooling system. The MaxValier satellite has a total mass of less than 16 kg; therefore the total mass of the telescope is limited to less than 3 kg. The scientists had to define scientific objectives for this miniature X-ray telescope, which can be reached with a small telescope but which are useful at the same time.
Since a small telescope lacks the effective area for high spatial resolution, μROSI is designed for high spectral resolution instead. The fast high-resolution spectrometer can measure the spectra of at least one hundred well-known bright X-ray sources and possibly even detect unknown transients. Since these bright X-ray sources are distributed over the entire sky, the mission is designed as a sky survey similar to ROSAT. The telescope is located on a sun-synchronous orbit, where the scanning motion will also allow measuring spectra of the Earth’s upper atmosphere and to observe the O2 line at 0.5 keV.
The X-ray data will be sent to Earth at amateur radio frequencies and will be evaluated by students from the participating South Tyrolean schools. This unique project thus opens up a new range for amateur astronomers. In addition to the μROSI X-ray telescope, the satellite also carries an Automatic Identification System (AIS), a CMOS image camera and a GPS sensor.
The project was launched in 2008 by a group of amateur astronomers at the Max Valier Observatory and ambitious teachers at the Max Valier Bolzano (GOB) and Oskar von Miller training centers in Merano (GOM) with the space company OHB and the Max Planck Institute for Extraterrestrial Physics (MPE) as partners. In addition to the scientific objectives, the project aims to enable pupils and teachers to gain practical experience with the various aspects of such a space mission. The electronics in the satellite have been developed by the electronics department at the Fachoberschule "Max Valier" in Bolzano. Part of the mechanical structure was produced by the mechanical engineering department. The automation department developed methods for sensor evaluation and determining the satellite’s orientation in space.