XRISM’s filterwheel

This filterwheel of the XRISM satellite was developed by SRON in the Netherlands. Each filter can be placed over the Resolve instrument and serves a different goal. There is a molybdenum grey filter to reduce the overall brightness of a source. The one made of beryllium filters out X-rays of unwanted energy. Another filter is made of polyimide-aluminium and avoids ambient contamination. The filter wheel also has space for filters to calibrate the Resolve instrument. This includes a radioactive 55Fe filter and modulated X-ray sources (MXS) to calibrate the energy scales of the instrument.