Meteoroid and space debris impacts in grazing-incidence telescopes

Abstract

Context. Micrometeoroid or space debris impacts have been observed in the focal planes of the XMM-Newton and Swift-XRT (X-ray Telescope) X-ray observatories. These impacts have resulted in damage to, and in one case the failure of, focal-plane Charge-Coupled Device (CCDs) detectors. Aims. We aim to quantify the future risks of focal-plane impacts in present and future X-ray observatories.Methods. We present a simple model for the propagation of micrometeoroids and space debris particles into telescopes with grazingincidence X-ray optics, which is based on the results of previous investigations into grazing-incidence hypervelocity impacts by microscopic particles. We then calculate micrometeoroid and space debris fluxes using the Micrometeoroid and Space Debris Terrestrial Environment Reference model (MASTER2005). The risks of future focal-plane impact events in three present (Swift-XRT, XMM-Newton, and Chandra) and two future (SIMBOL-X and XEUS) X-ray observatories are then estimated on the basis of the calculated fluxes and the model for particle propagation.Results. The probabilities of at least one impact occurring in the Swift-XRT, XMM-Newton, and Chandra focal planes, in a one year period from the time of writing in November 2007 are calculated to be ∼5% and ∼50% and ∼3%. First-order predictions of the impact rates expected for the future SIMBOL-X and XEUS X-ray observatories yield probabilities for at least one focal-plane impact, during nominal 5-year missions, of more than 94% and 99%, respectively. Conclusions. The propagation of micrometeoroids and space debris particles into the focal planes of X-ray telescopes is highest for Wolter optics with the largest collecting areas and the lowest grazing angles. Telescopes in low-Earth orbits encounter enhanced particle fluxes compared with those in higher orbits and a pointing avoidance strategy for certain directions can reduce the risk of impacts. Future X-ray observatories, with large collecting areas and long focal lengths, may experience much higher impact rates on their focal-plane detectors than those currently in operation. This should be considered in the design and planning of future missions.

Are STEREO Single Hits Dust Impacts?

“…This conclusion, however, does not mean that nanodust does not exist. Its existence has been predicted in a number of papers by Mann and colleagues, and there is evidence from very small holes in foils that such small, fast dust exists however (Carpenter et al, , ). We note that, at Saturn (Meyer‐Vernet et al, ; Moncuquet et al, ), dust has 10 times the time and distance to become entrained, but calculations do not seem to be available to compare with the observation.…”

The Dawn of Dust Astronomy

“…3) indicate that it is already in or near the self-destruction mode, also evidenced by the frequent collision avoidance manoeuvres of the International Space Station (ISS) with trackable debris. Micrometeoroid or space debris impacts damaged some focal plane detectors of the XMM-Newton and Swift-XRT X-ray observatories (Carpenter et al, 2008). Clustering in the times of impacts is indicative of dust generation events.…”

Accelerator experiments with soft protons and hyper-velocity dust particles: application to ongoing projects of future x-ray missions

“…The evidence [17], [18] that X-ray mirror shells can scatter soft protons and dust particles down to focal plane detector. stresses the need of dedicated accelerator tests to improve and validate the existing models for the assessment of the risk posed by scattering from mirrors.…”