AXAF


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AXAF

The Advanced X-ray Astrophysics Facility, originally intended by NASA to follow the Hubble Space Telescope as a long-lived X-ray observatory for the 1990s, with in-orbit servicing from the space shuttle. A direct successor to the Einstein Observatory, AXAF was to carry an array of large (1.2-meter outer diameter) coaxial grazing incidence mirrors in a nested configuration, high-resolution cameras using both CCDs and microchannel plates, and a cryogenically cooled X-ray spectrometer. Budgetary constraints led in 1992 to the restructuring of the AXAF into two smaller missions, AXAF-I (concerned with high-resolution X-ray imaging) and AXAF-S (dealing with X-ray spectroscopy). AXAF-I was scheduled for launch in 1998/99 into a highly eccentric orbit that would keep it out of the Earth's shadow for long periods, thereby maximizing its observation time. AXAF-S was to follow it into space in 1999, traveling in a near-Earth Sun-synchronous orbit to conduct high-resolution X-ray spectroscopy with no in-orbit servicing. In the event, NASA canceled AXAF-S, and its advanced X-ray spectroscopic instruments were transferred to the ill-fated Japanese Astro-E mission (see Astro-E2). Development of AXAF-I continued, however, and it was eventually successfully launched in July 1999 and renamed Chandra (see Chandra X-ray Observatory).
References in periodicals archive ?
AXAF is scheduled to fly into orbit aboard the Space Shuttle Columbia in September 1998.
These instruments cover a broader energy range than those aboard AXAF, but none of them produce particularly sharp images.
By the end of the year, the first scientific results from AXAF and FUSE will begin to roll in, joining the steady stream of discoveries from Hubble and the other orbiting eyes.
The thermal vacuum test was run with the 39-foot tall AXAF placed in a large sealed chamber that was pumped down to simulate the vacuum of space.
Since the AXAF instruments are designed to operate in a vacuum, this thermal vacuum test is the last time prior to launch when its key functions can be tested in a realistic environment.
The AXAF thermal vacuum testing process also provided opportunities for the operators of the AXAF Operations Control Center (OCC) in Cambridge, Mass.
The AXAF High Resolution Mirror Assembly (HRMA), the optical heart of NASA's third Great Observatory, was delivered on May 6 to TRW's Space Park satellite integration facilities in Redondo Beach.
AXAF is scheduled to be launched from the Space Shuttle in August 1998.
We are delighted with the timely completion of the HRMA's X-ray testing and its delivery to TRW," said Ed Wheeler, TRW's AXAF program manager.
TRW Space & Electronics Group is building AXAF for NASA's Marshall Space Flight Center, Huntsville, Ala.
TRW expects to begin assembling and testing the AXAF spacecraft during spring 1997, with integration of the spacecraft with its X-ray telescope and science instruments slated to begin in the fall of 1997.
The mirrors must be precisely aligned to focus X-rays from celestial sources onto science instruments located at the other end of the AXAF telescope.