Engineering model for the high-resolution imager (HRI) flown on the ROSAT (Roentgen Satellite) spacecraft, one of two detectors on the spacecraft. This imager consists of a pair of stacked microchannel plates backed by a grid of crossed wires. This HRI was developed for NASA by the Harvard-Smithsonian Center for Astrophysics. It comprises an improved version of an imager used on the earlier Einstein Observatory. ROSAT, named after the discoverer of X-rays, Wilhem Roentgen, was an international mission aimed at exploring the high-energy universe. It was developed in a cooperative effort between Germany, the United States and Great Britain. The satellite, which was designed and operated by Germany, was placed in orbit board a Delta II launch vehicle in June 1990 and collected data until February 1999. During that time it obtained an all sky survey in the X-ray region as well as detailed observations of many galaxies.

The orbiting x-ray telescope ROSAT used sets of wide metallic cylinders to "scoop up" incoming x-rays and focus them onto a detector like this one. The x-rays ricocheted down the cylinders and into a bundle of microscopic metallic straws in the HRI. The x-rays knocked electrons off the sides of the straws, which channeled the electrons onto a fine wire mesh screen. The resulting electrical impulses were used to create an image showing the intensity and distribution of the x-ray energy.

Transferred from the Smithsonian Astrophysical Observatory, courtesy of NASA