Two satellites, partly developed by the Swiss space technology company, Contraves Space, have entered orbit, after blasting off from the Baikonur cosmodrome in Kazakhstan, on a mission to monitor the solar wind.

The satellites, called Rumba and Tango, were launched by a Soyuz rocket and have joined two others, already in orbit, as the second part of the "Cluster mission".

If all goes according to plan, the four satellites will circle our planet in an elliptical, polar orbit, at distances of between 25,000 and 125,000 kilometres.

The satellite structures were developed and built by the Zurich-based Contraves Space company, and must support vital scientific instruments, liquid fuel for orbital manoeuvres, energy sources and other necessary equipment.

"The satellite structure is critical in that it has to hold and support all the payloads during the launch and the mission, even when there is zero gravity. The structure itself comes under extreme exposure during launch when it is vibrated and accelerated," Umberto Somaini, chief executive officer of Contraves Space, told swissinfo.

The mission is very much in the spotlight following a failed first attempt in June 1996, when four Cluster satellites were lost when the Ariane 5 rocket exploded just seconds after take-off.

Costs have been trimmed by 30 per cent since then, which partly explains the use of a Soyuz rocket for this latest attempt.

The European Space Agency says that four satellites in fleet formation should provide information of great importance. "The interactions between the solar wind and the magnetosphere - which protects the earth against solar winds - influence our own living environment and the Earth's climate as well," it says.

The most spectacular phenomena resulting from this interplay are the polar lights that appear at the Earth's poles.

Contraves Space is perhaps best known for its production of more than 130 payload fairings (the top part of a rocket, which protects the payload, usually a satellite) for the Ariane space programme.

However, it also produces mechanisms, for example in the Hubble Space Telescope, as well as scientific instruments and optical satellite communication equipment.

by Robert Brookes

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