Cluster mission launch bumped

Cluster: The first spacecraft to fly in formation

Europe's next major space project, Cluster II, has been delayed for three days to make way for an important mission to the International Space Station (ISS).

Both Cluster and the ISS's Zvezda service module were given 12 July as a launch date from the Baikonur space port in central Kazakhstan. A dual launch was never likely and now Russian and European space officials have confirmed that the much delayed Zvezda unit will be given priority.

The Cluster mission, which will deploy four identical satellites to study Earth's near-space environment, will blast off on 15 July at 12:40 GMT.

This launch will be used to put the first pair of Cluster satellites into orbit. A second launch to send up the other pair has been provisionally booked for 9 August.

That Zvezda should get the earlier launch is no surprise. Lengthy delays in the module's preparation have knocked the ISS programme seriously off track, and the US space agency, Nasa, would simply not tolerate another, unnecessary hold-up.

Cluster facts

Dimensions

2.9m diameter

1.3m high

50m antennae

Weight

Spacecraft 480 kg

Fuel 650 kg

Instruments 70 kg

Altitude

Minimum 25,500 km

Maximum 127,400 km

Space crews cannot live for extended periods on the embryonic space station until Zvezda is in place. The module is packed with air filters, has a waste disposal system and will help maintain the ISS at its required altitude.

Cluster II is not under the same pressure to launch. It is a "recovery mission". The first Cluster programme was destroyed on the maiden test flight of the Ariane 5 rocket in 1996.

The Cluster satellites will be the first spacecraft to fly freely in formation. They will study the physics of Earth's near-space environment, giving scientists better equations with which to forecast the violent space weather that can threaten satellites, astronauts and even power grids on the surface of the planet.

The dangers result from solar storms, which can bombard the Earth with speeding particles. The Sun's storm activity is expected to reach the maximum of its 11-year cycle in 2000.