BY PETER BOND
Posted: July 14, 2000
The four Cluster II satellites will be lifted into orbit, in pairs, on board Soyuz rockets provided by the Russian-French Starsem company. For this mission, the old Soviet era workhorse has been upgraded with the addition of a newly developed Fregat restartable upper stage.
The Soyuz will place the upper stage and its Cluster II payload into a preliminary orbit inclined at 64.8° to the equator. Then, 8 minutes 48 seconds after lift off, the Fregat payload assist module and its two spacecraft will separate from the booster. The Fregat main engine will fire almost immediately to achieve a circular orbit of approximately 200 km altitude. About one hour later, the engine will fire again to inject the spacecraft into a 200 km x 18,000 km elliptical orbit.
The two satellites will then be released, one after the other. Using their own onboard propulsion systems, they will gradually change their orbital inclination from 64.8° to 90°, eventually reaching the final operational orbit with an apogee of 119,000 km and a perigee of 19,000 km. They will be joined a few weeks later by the second pair of satellites. If all goes well, the science programme should begin in earnest around October.
Cluster to rise from the ashes
Anatomy of a Cluster II spacecraft
Unique 3-D science
Studying the Sun-Earth connection
Animation depicts the launch of a pair of Cluster 2 satellites aboard a Starsem Soyuz equipped with a Fregat upper stage.
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The first quartet of Cluster satellites is destroyed when Europe's Ariane 5 explodes soon after launch on June 4, 1996.
PLAY (216k, 18sec QuickTime file)
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