The largest X-ray telescope ever built has been launched by the European Space Agency (ESA). Earlier today, the Euro 690 m XMM X-ray telescope took off onboard the Ariane 5 heavy-lift launcher from French Guiana. XMM is ESA's most expensive and complex science observatory. After arriving in orbit later tonight XMM will be put in a safe 'standby mode' until after the New Year. Astronomers are concerned that computer bugs in communications equipment may damage the satellite if activated before the millennium. The telescope will become fully operational in March.
XMM will be in a highly elliptical orbit to keep it away from interference caused by the Sun’s glare. The telescope’s large size and unusual orbit explains why XMM was launched from Ariane 5, which is the largest heavy-lift vehicle currently in service. XMM consists of three advanced X-ray telescopes. They each contain 58 high-precision concentric mirrors. Each set of mirrors are designed to catch X-rays at different energy levels. The observatory is expected to remain in orbit for at least two years although a longer, extended mission is planned if fuel reserves do not become exhausted.