Artist's concept of the four Cluster 2 satellites operating together in space. Photo: ESA

Following the authorisation from the ESA Flight Acceptance Review Board on April 18, members of the Cluster 2 team are preparing for the Cluster 2 spacecraft long trip to the Baikonur launch site in Kazakhstan.

The Cluster 2 quartet are now scheduled to fly out in pairs from Basel-Mulhouse airport on April 27 and May 3. First to head east aboard the giant Antonov cargo plane, safely cocooned in their protective containers, will be FM6 and FM 7. They will be followed six days later by FM 5 and FM 8.

Meanwhile, testing of the trusters on board the Cluster spacecraft at the Lampoldshausen facilities of Deutsche Aerospace (DASA) is proceeding according to plans.

A Cluster 2 spacecraft carries eight thrusters, each of which contains four seals made of a soft polymer called Kalrez. The thrusters are required to maintain the attitude of the spacecraft and to manoeuvre them and change their separation distances so that they can achieve the maximum science return from their two year exploration of the magnetosphere.

The tests are intended to validate the proposed approach of partial seal replacement. Under current plans, the launches are set for July 12 and August 9, pending the results of the current tests.