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CLUSTER LAUNCH SUCCEEDS AT THE SECOND ATTEMPT

It must have been a nerve-racking experience for representatives of the European Space Agency, the launch service provider STARSEM and the various other companies involved in building the spacecraft, headed by the Earth Observation and Science Business Division of Astrium in Friedrichshafen, as lift-off was delayed for technical reasons. Originally it had been planned to launch the Soyuz booster with the first pair of satellites on 15 July, but when a communication problem developed between the rocket and the ground station no one wanted to take any risks. Then finally at 2.39 pm CET on 16 July they were put out of their misery as the Soyuz roared upwards into the skies.

Shortly afterwards came the good news that the payload fairing had successfully separated and the Fregat upper stage had ignited without complications. When after another hour and a half of agonising waiting the Clusters had finally separated from the stage and the ground station in Kiruna, Sweden acquired the first signals from the spacecraft, there was understandably much jubilation.

The urgency of the research programme had in April 1997 led to the decision to repeat the mission, and by reorganising the ESA budget and using the Soyuz booster it was possible to keep costs relatively low at around DM 600 million ($290 million). Hundreds of scientists and engineers now ventured a second attempt.

Their optimism was quite infectious: on the very day of the launch ESA's Scientific Programme Director, Professor Roger-Maurice Bonnet, announced the winner of competition in which entrants from all around Europe had been invited to come up with a suitable name for the satellites. The winner out of more than 5000 entries was Raymond Cotton from the United Kingdom, who had suggested the names Rumba, Salsa, Samba and Tango. Cotton and his wife are fond of dancing, and they felt that these names best reflected the way the satellites will dance through the heavens in formation; moreover, they are names which mean something to people from all around the world. Their arguments won the day.

FM-6 (flight model) "Salsa" and FM-7 "Samba" are now orbiting in space, and over the coming weeks their on-board propulsion systems will be ignited six times, nudging them into their final polar orbit. To enable them to do this, the satellites have a large quantity of fuel which comprised more than half of their take-off weight.

All that remains now is for FM-5 "Rumba" and FM-8 "Tango" to join them on 9 August. This will be followed by a three-month period of instrument calibration and systems tests before the quartet will finally embark on studying the interactions between the sun and the Earth's magnetosphere with a precision not previously achieved, a mission which will run for a minimum of two years.

From page 56 of FLUG REVUE 9/2000