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Space scientists in Japan hope to launch a new type of X-ray spectrometer
into orbit this week. Instead of measuring X-rays in the conventional way by
converting them into an electrical charge, the XRS will measure the heat created
by individual X-ray photons. This demands a high sensitivity, so the
spectrometer will be cooled close to absolute zero—to 0.06 kelvin. The
XRS, mounted on a spacecraft called Astro-E, will turn its sights on galaxy
clusters, supermassive black holes, neutron stars, supernova remnants and the
coronas of hot stars.