XMM ready for launch in December, a month earlier than envisaged!
10 June 1999The European Space Agency's XMM mission had until very recently been officially set to liftoff on 21 January 2000. Now, by mutual agreement between the ESA project management and Arianespace, the launch of the X-ray astronomy mission by an Ariane-5 has been rescheduled to mid-December this year.
Explaining the decision to bring the launch forward, ESA's XMM Project Manager Robert Laini said: "It was a result of the extra capability provided by Ariane-5. A greater knowledge of the launcher after the 502 and 503 qualification missions allowed Arianespace to tell us that the vehicle could carry XMM to a higher altitude before it is released. Our spacecraft is also lighter than originally expected, approximately 100 kg."
This good news allowed the XMM project team to open the launch window a month earlier. The spacecraft will also be carrying more fuel for its in-orbit life. Another factor allowing the launch to take place sooner, according to Robert Laini, is an uneventful series of tests upon the spacecraft with no surprises, allowing the team to have XMM ready earlier. But he emphasized: "We have cut no corners. All the tests that were planned have been completed successfully."
The spacecraft, whose two halves were mated on 26 May, will now complete its final tests at ESA's ESTEC technical centre in Noordwijk, including electrical verifications and accoustic tests at the start of July. There will be a solar array deployment test in mid-August. By then a giant satellite container will have been delivered and the spacecraft will be packed for shipping on one of the Arianespace vessels to French Guiana. Departure from Rotterdam is scheduled for mid-September.
The launch campaign, beginning at the end of September, will take place entirely in the Ariane-5 Final Assembly Building (BAF), in its satellite preparation area, leading up to a launch now nominally set for 15 December.
The prospect of having XMM in orbit sooner also greatly pleases the scientific community, eagerly waiting to use the space observatory.