Testing the XMM lower module mass properties at ESA/ESTEC

The scientific objectives of the XMM-Newton mission, for high-throughput X-ray spectroscopy, call for a powerful imaging instrument with the largest possible collecting area, for high-quality spectral measurements of faint sources down to 2x10^-15 erg/cm2/s, together with fast low- and medium- resolution spectroscopy of brighter objects.

An assembly of 51 mirrors, carefully sized, formed and nested one inside another, makes this the most sensitive X-ray telescope ever built. XMM will carry three identical telescopes of this kind.