AXAF
Advanced X-Ray Astrophysics Facility

The Advanced X-ray Astrophysics Facility is one of the four Great Observatories (along with HST, GRO, and SIRTF). AXAF will study the composition and nature of galaxies, stellar objects and interstellar phenomena as well as basic issues in theoretical physics using the most sensitive X-ray telescope ever built. International participants include the UK, Germany, and the Netherlands. Originally consisting of 2 separate spacecraft, the AXAF program was reduced to a single spacecraft in 1993 due to fiscal constraints. Satellite operations will be conducted by MSFC using NASA's Deep Space Network.

Spacecraft
3-Axis stabilized, zero momentum biased control system. Solar arrays generate over 2 kW. Light weight composite structure. Six reaction wheels. Four 2-degree-of-freedom dry tuned rotor gyros. Three 40 AHr nickel hydrogen batteries. Two 1.8 Gbit solid state recorders can store 18.8 hours of data per recorder.

Payload
X-ray telescope consisting of four pairs of nearly cylindrical mirrors, ranging from 1.4 meters in diameter to 0.68 meters in diameter. These mirrors focus X-ray energy over a 10 m focal length onto two of the four science instruments, the High Resolution Camera (HRC) and the AXAF CCD Imaging Spectrometer (ACIS). Also carried are two non-focal plane instruments, the High-Energy Transmission Grating (HETG), and Low-Energy Transmission Grating (LETG).

Country of Origin	United States
Customer/User	NASA, MSFC
Manufacturer(s)	TRW
Size	Length 12.2 m, solar arrays span 18.9 m
Launch	September 1998 by Shuttle with IUS booster
Orbit	10,000 km x 40,000 km, incl. = 28.5 deg.
Design Life	5 years
Related Sites	AXAF site at MSFC Jennifer Green's AXAF Page AXAF Science Center