The Aborted Launch of Cluster I

Debris falling to earth after the break-up

(Both photos: A. Nogues/SYGMA for ESA/CNES)

Cluster I was launched on June 4, 1996, on the first qualification flight of Ariane 5. The rocket performed nominally up to about 37 seconds, at which point it veered off course, was ripped apart, and exploded, at a height of about 4 km. Some of the Cluster satellites and their instruments were recovered from the nearby swamps, totally destroyed.

The Report by the Inquiry Board finds that a programming error in the navigation software, which was inherited from Ariane 4, caused the steering program to crash: mere test data were subsequently sent to the steering jets. The subprogram where the error occurred was only meaningful before lift-off, but was allowed to run an additional 40 secs.

More photos

retrieving parts.

Recovery of the Cluster Mission

The Proposed Phoenix Mission

For each of the 11 experiments on board Cluster, 5 units had been built: four to fly on the 4 spacecraft, and one reserve unit.
As a first and immediate attempt to recover the mission, a fifth spacecraft was quickly assembled with the reserve units. Named the Phoenix Mission, it was not intended as a replacement for Cluster but rather only as a stop-gap.

Cluster II

The real recovery program required more time to be set in motion, since it would cost more and involve intensive commitments from the participating institutions. Negotiations were finally completed at the end of 1996.

Cluster II was to be built, as much as possible, as an exact copy of the original lost Cluster I, in order to avoid development and testing expenditures (both in time and money). The Phoenix spacecraft, which was already being assembled from the old flight spaces, was then complemented by 3 additional spacecraft to make up the fleet of 4 once again. Because of procurement and staff problems (old parts no longer available, people retired) an exact duplicate of the original is not 100% realizable; however, the differences were kept to a minimum.

Cluster II was launched in the summer of 2000 on two Soyuz spacecraft from the Baikanur Cosmodrome. See launch news.

Back to Cluster page.

P. W. Daly
02-11-2004