Adaptive grazing incidence optics for the next generation of x-ray observatories

Abstract

Advances in X-ray astronomy require high spatial resolution and large collecting area. Unfortunately, X-ray telescopes with grazing incidence mirrors require hundreds of concentric mirror pairs to obtain the necessary collecting area, and these mirrors must be thin shells packed tightly together... They must also be light enough to be placed in orbit with existing launch vehicles, and able to be fabricated by the thousands for an affordable cost. The current state of the art in X-ray observatories is represented by NASA's Chandra X-ray observatory with 0.5 arc-second resolution, but only 400 cm 2 of collecting area, and by ESA's XMM-Newton observatory with 4,300 cm 2 of collecting area but only 15 arc-second resolution. The joint NASA/ESA/JAXA International X-ray Observatory (IXO), with ~15,000 cm 2 of collecting area and 5 arc-second resolution which is currently in the early study phase, is pushing the limits of passive mirror technology. The Generation-X mission is one of the Advanced Strategic Mission Concepts that NASA is considering for development in the post-2020 period. As currently conceived, Gen-X would be a follow-on to IXO with a collecting area ≥ 50 m 2 , a 60-m focal length and 0.1 arc-second spatial resolution. Gen-X would be launched in ~2030 with a heavy lift Launch Vehicle to an L2 orbit. Active figure control will be necessary to meet the challenging requirements of the Gen-X optics. In this paper we present our adaptive grazing incidence mirror design and the results from laboratory tests of a prototype mirror.