Speaker
Mr
Josef Sommer
(Astrium Bremen)
Description
The imperilment in space by debris or incapacitated spacecraft, in particular in nearly polar low earth orbits, has materialized latest after the collision between an Iridium and a superannuated Kosmos satellite in February 2009. Today all space agencies are working more or less intensive on concepts for space waste disposal. A key technology for this is a navigation system, which allows the approach to an uncooperative passive target in low earth orbits down to a distance, where capturing is possible. The final distance depends on the capture system and varies between 1m for a manipulator arm and several 10m for tether based systems like the net.
Today’s RVD systems require a cooperative target, i.e. there is a need for target pattern and/or a intersatellite RF link for data exchange (e.g. RGPS). For old or incapacitated spacecraft this is not available, so that the navigation must rely on active sensors (radar, laser scanner, flash light) or exploit environmental illumination or temperature (video camera and IR sensors). In close vicinity to the target, it is not sufficient to measure distance and line of sight, but the target attitude needs to be known as well. This requires onboard real time image processing, whereby the images may be generated by a video or IR camera, a laser scanner or an imaging radar.
The envisaged presentation shows the results achieved within Inveritas and RTES, Astrium internal projects subsidised by the Federal Ministry of Economics and Technology through the German Aerospace Center, DLR, Space Management,. It describes a navigation system layout for a rendezvous with an uncapacitated but known space vehicle (satellite or upper stage), i.e. the knowledge of the S/C geometry can be exploited for the onboard image processing. Three elements are of particular importance for the rendezvous navigation
• the navigation sensor (video camera, PMD camera, infrared camera, scanning Lidar, flash Lidar, radar)
• the processing of the raw data (image, point cloud)
• the processing/W requirements
First a short mission overview will be given and the top level requirements as a function of the typical mission phases will be derived. Then sensor candidates and their characteristics will be reviewed for potential application as a rendezvous sensor and needs for data processing are assessed. For the selected concept preliminary performance results are shown and processing needs are identified and compared to existing processing hardware or hardware under development. Finally the laboratory environment for navigation design and analysis including the use of a test facility for sensor testing may be described.
