The Observatory

Fully assembled, XMM-Newton stands ten meters tall. It is shown here during acoustic testing at ESTEC in July 1999.

The XMM-Newton observatory is the biggest science satellite ever built in Europe, and is ESA's second cornerstone of its Horizon 2000 program. Its name derives from its three X-ray telescopes, each containing 58 high-precision concentric mirrors.

The spacecraft consists of three main sections:

a seven meter long black telescope tube;
a squarish service module also carrying three 'mirror modules' at its forward broader end;
the focal plane assembly housing the X-ray cameras and detectors at its other extremity.

This 'tri-clops' with its golden eyes is more than 10 meters long, just able to fit into the payload bay of the Ariane-5 rocket. XMM-Newton receives power through its pair of solar panels, giving it a 16 meter "wing" span.

The spacecraft's design features extremely high mechanical stability. Its position and control systems allow it to point at targets in the sky over long periods with a remarkable pointing accuracy of 0.25 arcsec over a ten second interval. This is about 1/8000^th the diameter of the Moon in the sky, or equivalent to using a hand-held telescope and clearly seeing a melon placed 180 km away!

XMM-Newton's Construction

The space observatory was built in conditions of exceptional cleanliness to preserve its ultra-polished mirrors. Another requirement was its light-tightness to avoid extraneous light. The XMM-Newton program, with the parallel construction of two models and the manufacture of the proto-flight model, was conducted in the space of just less than three years. Most of the testing was done on a modular basis, and the calibration of its mirror modules required a custom-built vertical test facility.

XMM-Newton weighed 3.8 tons on the launch pad. It was designed to operate for at least two years in orbit, and it has already exceeded this specification. It is expected to be operational for many more years; the hydrazine propellant aboard its service module could be enough for a total lifetime of ten years.