The Astro-E Observatory will employ a high-resolution X-ray spectrometer ba
sed on a 32 pixel array of microcalorimeters with an energy resolution of a
bout 12 eV at 6 keV (the Fe-K region). This will provide spectral resolving
power 10 times higher than any other non-dispersive X-ray spectrometer. Th
e instrument incorporates a three-stage cooling system capable of maintaini
ng the temperature of the detector stage at 60 mK for about two years in or
bit with a 97% duty cycle. The array sits at the focus of a grazing inciden
ce conical mirror. The quantum efficiency of the microcalorimeters and the
reflectivity of the X-ray mirror system combine to give high throughput ove
r the 0.3-12 keV energy band. This new capability will enable the study of
a wide range of high-energy astrophysical sources with unprecedented spectr
al sensitivity. (C) 2000 Published by Elsevier Science B.V. All rights rese
rved.