XMM now standing 10 metres tall and launch in sight!
26 May 1999The European Space Agency's X-ray astronomy mission XMM is today one step closer to lift-off, with the mating of the two halves of the satellite. This occurred on 26 May at the ESTEC technical centre at Noordwijk in the Netherlands. ESA's second 'cornerstone' mission is now just over six months away from launch.
Over the past months, both parts of the spacecraft - its focal plane assembly and the module with its mirror support platform, each with a section of the 7.5m telescope's central tube - have independently and successfully completed their environmental tests at ESTEC. It was here too that the three mirror modules and an optical telescope were installed on the satellite.
The joining of the two satellite halves, both approx. 5 m long, took place in the XMM integration area. The upper focal plane assembly was hoisted by a gantry crane above XMM's lower section, itself surrounded by scaffolding. As it slowly descended, controlled with infinite precaution by specially trained technicians, the scene was watched from a visitors gallery by members of the XMM team, several of the mission's principal investigators and representatives from Arianespace, including Arianespace XMM mission manager, Daniel Biedermann.
After being lowered into place, the first of 64 bolts around the 6 m diameter interface plane was inserted. To mark this new milestone in the programme, three years after the start of construction of flight hardware, a special "golden bolt" was positioned by Dr Hubert Hofmann, Executive Vice President Science, Earth Observation and Meteorological Satellites, Dornier Satellitensysteme, XMM prime contractor. By his side was Robert Laini, ESA's XMM Project Manager.
"It is an exciting moment to see the XMM satellite ready for the last tests in Europe. I would like to thank all members of the XMM team for reaching this significant milestone. I'm convinced that the upcoming launch campaign will also be conducted in a positive spirit. I'm sure that XMM will deliver excellent data to the scientific community."
Robert Laini replied: "I would like to congratulate everybody at Dornier. It's an exceptional achievement to have built such a large spacecraft and to have reached this stage only three years and two months after we signed the industrial contract".
Thoughout the day regular updates from the clean room were published on the XMM web page. These 'live updates' will be a regular feature of the web page from now until the spacecraft is ready for shipping to the Kourou launch site.
As from the end of this May, the fully assembled satellite is to complete accoustic tests at ESTEC and final verifications will last virtually until it is time to pack XMM for its journey to French Guiana. The present schedule is to have the satellite in Kourou by end September, with a campaign leading to a launch at the end of this year.
With the most sensitive X-ray space telescope ever conceived, XMM is about to revolutionise X-ray astronomy. The XMM mission will conduct prolonged observations of more than one million X-ray sources in the universe, violent and changing places such as black holes, binary stars and vestiges of supernovae, where temperatures reach millions of degrees.
The name of the mission stems from the design of its three mirror modules, a masterpiece of engineering. Each is constituted of 58 super-polished, wafer-thin gold-plated mirrors. With a total optical surface of 150 m2, they are the smoothest and largest X-ray collectors ever built in the world.
On the spacecraft's focal plane are situated three highly sensitive cameras and two high-resolution spectrometers to image X-ray sources and allow their spectral analysis. The satellite also carries a 30 cm optical telescope for simultaneous observation of the same regions of the sky in visible and ultraviolet wavelengths.
The 3.9 tonne spacecraft is to be launched by an Ariane 5 from Kourou into a 48-hour elliptical orbit with a 7000 km perigee and an apogee of 114 000 km.