XMM (X-ray Multimirror Mission) is an astronomy spacecraft of the European Space Agency and was launched by a 746-ton Ariane 5 rocket from Kourou at 14:32 UT on 1999 Dec 10. It is the first launch of a functional spacecraft by this latest model. The 3.7-ton spacecraft carries three 13-meter long, 4.5-meter diameter (tapering down to a smaller diameter near the focal plane) x-ray telescopes. Each of these cone-shaped telescopes carry 58 concentric reflectors of progressively smaller diameters, with each annular space of 2-4 mm thickness sandwiched between adjacent reflecting surfaces. At the focal plane are situated three x-ray cameras, one for each telescope. These cameras, named EPIC (European Photon Imaging Camera) have CCD detectors. Each of two of the detectors carry seven silicon chip wafers, each of which is made up of a matrix of 600 x 600 thin (40 micron) MOS pixels; they respond to the soft x-rays. The third detector has a single wafer of a thick (300 micron) "PN-CCD" with 400 x 400 pixels, responding to the harder x-rays. The area of the PN-CCD array is 36 sq-cm. The pointing accuracy of the telescope array is 0.25 seconds of arc, sustainable during a 10-second period. Two of these three imaging telescopes have a complementary role also: to provide x-ray spectra through Reflecting Grating Spectrometers (RGS), each containing 600 grooves/mm. About half of the x-rays entering each telescope is piped out into these RGSs. Finally, these x-ray observations are complemented by an Optical Monitor (OM) telescope, equipped with CCD detectors and covering visible and UV wavelengths. The 30-cm aperture camera has a field of view of 17 x 17 arc min (about the same as the x-ray cameras). The initial orbital parameters were period 48 hr, apogee 114,000 km, perigee 7,365 km and inclination 38.7 deg.
XMM is a an x-ray telescope containing three mirror modules each consisting of 58 nested Woljer type-1 mirrors and covering the energy range from 0.1 to 10 keV. The effective area of the three modules combined is about 6500 sq cm between 0.1 and 1 keV and about 2000 sq cm at 10 keV. The spatial resolution is about 30 arc-seconds and the sensitivity is about 10E-15 erg/cm*2/s for one orbit. The instruments consist of the European (x-ray) Photon Imaging Cameras (EPIC), the Reflection Grating Spectrometers (RGS), and the Optical Monitor. The latter instrument is to provide simutaneous observations of the optical counterparts of x-ray sources.
The spectral resolution ranges from about 50 for the cameras at 0.5 keV to about 600 for the spectrometers at 0.3 keV. Among the goals for the 10 yr lifetime of XMM are: understanding the diffuse x-ray background, mapping the x-ray emitting gas in clusters of galaxies, unbiased surveys of galaxies and of stars, diagnostic studies of accreting binary stars, temporal spectroscopic studies of AGN's and spectral studies of supernove remnants in nearby galaxies.
Alternate Names
Newton
X-ray Multimirror Mission
Facts in Brief
Launch Date: 1999-12-10
Launch Vehicle: Ariane 5
Launch Site: Kourou, French Guiana
Mass: 2400.0 kg
Nominal Power: 1000.0 W