The XMM is an international cooperative project between NASA and the European Space Agency (ESA). The XMM is
a High Throughput X-Ray Spectroscopy Mission which is the second cornerstone of the ESA longrange scientific plan to be launched on an Ariane V rocket in 1999. NASA is providing significant support in two of the three instruments to be flown on the spacecraft.

NASA is furnishing the reflection gratings for the Reflection Grating Spectrometer provided by the Scientific Research Organization of the Netherlands (SRON) - Laboratory for Space Research. The instrument will provide unparalleled sensitivity for high resolution spectroscopic observations of cosmic sources in the soft X-ray band.

NASA is also supplying the data processing unit for the Optical Monitor (OM) being provided by the Mullard Space Science Laboratory of England. The OM will provide optical and UV data simultaneously with the x-raymeasurements.

Salient Features:

Project Start: U.S. Co-Investigators selected June 1989
Spacecraft Weight: 2,374 kg
Planned Lifetime: 2 years with the possibility of more than 10 years
Orbit: 70,565 km by 1,000 km, 60 Degrees inclination
Launch: ARIANE V from Guiana, South America, December 1999

Instrument Complement:

Three Mirror Modules
Two X-ray Reflection Gratings
Three European Photon Imaging Cameras
Optical Monitor
CCD X-ray Detectors