Meteoroid and space debris impacts in grazing-incidence telescopes

TL;DR

This paper models the impact risks of micrometeoroids and space debris on grazing-incidence X-ray telescopes, estimating probabilities for current and future observatories, highlighting the need for impact mitigation in telescope design.

Contribution

It introduces a simple impact propagation model and provides impact probability estimates for existing and upcoming X-ray observatories, emphasizing increased risks for future large-area telescopes.

Findings

Current impact probabilities are 3-50% annually.

Future missions have over 94% impact risk in 5 years.

Large telescopes face significantly higher impact risks.

Abstract

Micrometeoroid or space debris impacts have been observed in the focal planes of the XMM-Newton and Swift-XRT X-ray observatories. These impacts have resulted in damage to, and in one case the failure of, focal-plane Charge-Coupled Device (CCD) detectors. We present a simple model for the propagation of micrometeoroids and space debris particles into telescopes with grazing incidence X-ray optics. 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. 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. 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.