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AXAF-S (Advanced X-Ray Astronomy Facility - Spectrometer) was the X-ray spectroscopy mission spun off from the original AXAF X-ray observatory. AXAF-S was to be a part of NASA's Great Observatories and was to measure high energy X-rays, emitted from such objects as black holes, neutron stars, and quasars.

The mission was to feature only one instrument, the XRS X-ray spectrometer, which was to provide X-ray spectra with a resolution of ~12 eV over the energy range of 0.3 to 10 keV by using calorimeters cooled to a temperature of less than 0.1 K. To provide this low temperature, it used an adiabatic demagnetization refrigerator, which in turn was cooled by superfluid Helium.

The AXAF-S spacecraft consisted of a 4 m optical bench (0.75 m in diameter), a 1090 liter, 2 m diameter Dewar bottle surrounding the science instruments (for cooling of the X-ray calorimeters) mounted at the end of the optical bench, and a 1.8 m × 2 m × 1.4 m electronics mounting structure (known as the "spacecraft bus") built around the aft half of the optical bench. The two solar array wings (6.2 m × 2 m each) are mounted to the "spacecraft bus".

AXAF-S was to be a low earth orbit mission launched on a Delta-7920 from Vandenberg AFB in 1999.

The mission was cancelled in October 1993 and the XRS instrument was integrated into the Japanese Astro-E satellite.

Nation: USA
Type / Application: Astronomy, X-Ray
Operator: NASA Marshall Space Flight Center
Contractors: NASA Marshall Space Flight Center
Equipment: XRS
Power: 2 deployable solar arrays, batteries
Lifetime: 5 years
Orbit: 1176 km polar orbit
Satellite COSPAR Date LS Launch Vehicle Remarks
AXAF-S - cancelled Va SLC-2W Delta-7920


  • Matthew B. McCollum, Matthew B. McCollum, Bonnie F. James: "Operating in the Space Environment: A Spacecraft Charging Study of the Advanced X-ray Astrophysics Facility-Spectroscopy Spacecraft"

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