April 22, 1998

	AXAF in final assembly.
	X-rays from nearly 150-million-degree-Fahrenheit gas surrounding the double cluster of galaxies Abell 2256. The two clusters, which contain more than 500 galaxies and lie at a distance of a billion light-years, are in the process of merging.
	X-ray emission from hot gas and stars in the vicinity of supernova 1987A. The supernova was first observed on February 23, 1987, in the Large Magellanic Cloud (LMC). The LMC is a small companion galaxy of the Milky Way at a distance of about 170,000 light-years.
	X-rays from a cluster of very young, hot stars in the Orion Nebula. This nebula is part of the sword of Orion, the Hunter, which is one of the best known of the constellations.

The third of NASA's Great Observatories, the Advanced X-Ray Astrophysics Facility (AXAF), is being readied for a December 1998 launch by the space shuttle Columbia (STS-93). The top image above shows the 45-foot-long, 5-ton observatory during the final stages of assembly.

The telescope is currently going through a series of thorough, pre-launch tests to ensure that it will be able to withstand the extreme vibrations and noise of launch and that its science instruments will work as intended. The prime contractor, with responsibility for assembly of AXAF, is the TRW Space and Electronics Group in Redondo Beach, CA.

AXAF will "see" the sky ten times sharper in X-rays and detect objects 50-100 times fainter than any previous X-ray telescope has been able to. These capabilities will give us a new perspective on many of the high-energy events in the universe, such as colliding galaxies, quasars, supernovae, X-ray emissions from very young and hot stars, and the extreme conditions in the vicinities of black holes.

AXAF will take an important place among NASA's other Great Observatories: The Hubble Space Telescope (HST), which was launched in 1990 and serviced by the space shuttle in 1993 and 1997; the Arthur Holly Compton Gamma Ray Observatory (CGRO), which was launched in 1991; and the Space Infrared Telescope Facility (SIRTF), which is currently being built and is scheduled for launch in 2001.

AXAF's spectral sensitivity will fall between that of the HST (sensitive in the near infrared, visible, and ultraviolet wavelength bands) and the CGRO (sensitive to high-energy X-rays and gamma rays). Scientists from the US and the international astronomical community will use the observatory over an anticipated mission lifetime of at least five years.

More Cool Stuff

For two recent press releases on AXAF, one by NASA (March 12, 1998) and the other by TRW (February 9, 1998), go to:

ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1998/98-043.txt

http://www.businesswire.com/trw/bw.020998/600917.htm

The TRW homepage for AXAF is at:

http://www.trw.com/seg/sats/AXAF.html

For a summary of space shuttle flight STS-93 (crew, images, vehicle, etc.), which will launch AXAF, go to:

http://hea-www.harvard.edu/~jcm/space/axaf/

For information on the other Great Observatories, go to:

http://fpd-b8-0001.gsfc.nasa.gov/440/440home.htm (HST)

http://erbscobe.gsfc.nasa.gov/ (CGRO)

http://sirtf.jpl.nasa.gov/sirtf/ (SIRTF)

The above three X-ray images were taken by the German/US/UK ROentgen SATellite (ROSAT). To view more ROSAT images, go to:

http://heasarc.gsfc.nasa.gov/images/rosat/

For a description of the different wavelength bands of the electromagnetic spectrum, go to:

http://observe.ivv.nasa.gov/nasa/education/reference/emspec/emspectrum.html

As part of its Learning Technologies Project (LTP), NASA supports a number of educational Web sites that have excellent material on the space sciences:

http://observe.ivv.nasa.gov/nasa/education/edu/edudocs/topic_space.html