An imaging X-ray fluorescence spectrometer for near earth objects

We propose a novel imaging X-ray spectrometer to be flown on a space missio n to a Near Earth Object (NEO) (the Moon, a near Earth asteroid or a comet) . In either of the first two cases the instrument will record X-ray fluores cence excited from the surface by the solar X-ray flux to form "composition al maps" of its surface, providing valuable information on the evolution of these objects. In the case of a comet, the device will study the X-rap emi ssion resulting from its interaction with the solar wind. During cruise when the spacecraft is en-route to the NEO the instrument wil l be used to make astronomical observations of Active Galactic Nuclei (AGN) , X-ray binary stars and coronal sources in star clusters such as the Pleia des or Hyades. The instrument, proposed for ESA's SMART-1 mission, is a miniature telescop e, of 37.5 cm focal length, based on microchannel plate (MCP) optics and ch arged coupled device (CCD) detectors providing both imaging and a medium re solution similar to 50-100 eV spectroscopic capability; sufficient to resol ve the L lines of Ca, Ti, Fe, and the K lines of O, Mg, Al and Si with an a ngular resolution similar to 10 arcmin and a 6 x 6 degrees field of view. ( C) 1999 Elsevier Science B.V. All rights reserved.