Posted: Wed, Jan 9, 2002, 8:01 AM ET (1301 GMT)
Engineers have traced the failure of an Ariane 5 last year to water in an upper stage engine, Space News reported Tuesday. Tests of the Aestus upper stage engine in Germany have revealed that traces of water in the plumbing of the Aestus upper stage engine caused a "combustion instability" that reduced the engine's thrust, placing the booster's payload into an orbit lower than planned. The engine is routinely filled with water for hydraulics tests during assembly, and Arianespace officials believe the engine was not properly dried out before use. The July 2001 launch failure stranded two satellites, BSAT-2b and Artemis, into low orbits. Artemis is moving into geosynchronous orbit using its own thrusters, while BSAT-2b was written off as a total loss. Arianespace plans to return the Ariane 5 to service in late February with the launch of ESA's Envisat earth sciences spacecraft.

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