Detector for microparticles in space

Space debris increasingly endangers the unlimited usability of near-Earth space. Besides the pay loads (satellites), a large amount of microparticles has been released into space with more than 4,000 launches worldwide. These are, for example, slag residues of rocket engines or fragments generated by fuel explosions. Due to the usually high relative velocity in the case of a collision Ð typically 10Êkm/s, even particles in the micrometer regime can cause damage. In order to assess and minimise the risk, in-situ measurements provide the data base for the modelling of the particle environment.

For the development of detectors for particles in the range of a few micrometers, PTB and eta_max Space GmbH in Braunschweig have started a research collaboration. Together with further partners from Jena and Braunschweig, a two-stage detector is being developed (AIDA Ð Advanced Impact Detector Assembly) which will provide a clearly lower measurement uncertainty and a higher reliability compared to existing measuring procedures. The first detector stage intends to use laser-light sheets for a contact-free measurement of the velocity vector, and the second stage measures the kinetic energy of the particle impacting on a detector surface.

The development of the second detector stage has been successfully completed. The prototype of a calorimetric impact-energy detector makes use of a 16 x 16 thermopile array equipped with suitably structured metallic absorbers (e.g. made of gold foil). The detector has been successfully tested at the particle accelerator of the Max Planck Institute for Nuclear Physics in Heidelberg. The energy measuring range of such a detector can be adapted to a particular mission by scaling the absorber thickness.