Nancy Neal
Dec. 10, 1999

(Phone: 301-286-8955)

RELEASE NO: 99-137


American scientists are anxiously awaiting the launch of the European Space Agency’s X-Ray Multi Mirror
(XMM) spacecraft, set to lift off Dec. 10 from French Guyana on an Ariane 5 launch vehicle.

The XMM spacecraft, an X-ray satellite designed to provide high quality X-ray spectra of X-ray sources from
black holes to very hot objects created when the Universe was very young, is a European Space Agency
project with contributions from NASA. NASA’s involvement in the mission includes provision of critical
components for two of the spacecraft’s three science instruments and participation in the
science-observing program. Based upon the initial competition for observing time, U.S. scientists will
receive about one fifth of the observing time on the spacecraft during its first two years in orbit.

NASA’s Goddard Space Flight Center (Greenbelt, Md.) provided technical oversight of the U.S. provided
hardware that is flying aboard the spacecraft. Goddard also will oversee the U.S. guest observer program
wherein selected scientists are awarded observing time on the new observatory to gather science data.
Goddard will provide support to U.S. guest scientists in the form of data archives, technical guidance and
software support.

“Goddard will be providing support for U.S. scientists using this world class observatory and we are
extremely optimistic that this will result in first class science,” said Goddard scientist Dr. Richard
Mushotzky who is part of the XMM science team.

U.S. hardware co-investigator, Dr. France Cordova from the University of California at Santa Barbara,
contributed to the construction of two of the European instruments. Cordova and co-workers provided the
data processing unit, the digital electronics modules, software and science support for the Optical Monitor
(OM) instrument. Another U.S.
co-investigator, Dr. Steve Kahn from Columbia University in New York City, provided two reflection grating
assemblies for the Reflection Grating Spectrometer, data analysis software and science support.

“Both of these instruments are state-of-the-art and the Reflection Grating Spectrometer in particular has
advanced new technology,” said Mushotzky.

The third instrument comprising the science payload, the European Photon Imaging Camera (EPIC), has
silicon chips that can obtain medium spectral resolution x-ray spectra from sources much fainter than ever
before. The RGS will analyze the spectra in more detail and with greater resolution. The Optical Monitor will
observe the same part of the sky as the x-ray telescopes but in the ultraviolet and optical wavelengths. This
will give astronomers complementary data on the X-ray sources observed with the EPIC and RGS

The spacecraft has four telescopes. Three of them are X-ray telescopes with the combined surface area of a
tennis field, 120 square meters. However, due to the fact that the x-rays are focussed via reflection at very
shallow angles, the effective collecting area for x-rays is 100 times less. In addition to the large collecting
area afforded by XMM, the spacecraft will operate in an orbit that will allow it to take long and uninterrupted
observations. The fourth telescope is a 30-centimeter optical telescope, which, by virtue of its operation
above the
atmosphere, is much more sensitive than a similar telescope on the ground.

The name of XMM stems from its multiple mirrors. XMM, with the largest x-ray collecting area flown to
date, will allow astronomers to gather and analyze more

X-ray sources quicker than with previous space observatories.
Scientists expect XMM will explain a number of cosmic mysteries, ranging from black holes to the origin of
the universe. XMM will investigate supernova remnants, black holes, magnetically active flare stars and

XMM, a world-class observatory, is the second cornerstone mission of ESA’s

Horizon 2000 program. Its large effective area and soft x-ray
spectroscopic capabilities very nicely complement the high
angular-resolution and higher energy x-ray spectroscopic capabilities of NASA’s recently launched Great
Observatory for x-ray astronomy, the Chandra X-ray Observatory. The minimum mission life of the
spacecraft is two years but it is expected to last much longer.