The European Space Agency's Ariane 5 ECA rocket has been greenlighted for blast-off tomorrow from Kourou spaceport in French Guiana. The 50m (160ft) high vehicle will carry an XTAR-EUR telecommunications satellite, the Sloshsat-FLEVO experimental mini-satellite - designed to "investigate the dynamics of fluids in weightlessness" - and a telemetry/video imaging package which will gather flight data.

ESA rocketeers are hoping that the payload does not actually end up in the Atlantic - as happened during the last Ariane 5 ECA launch in 2002. The exploding rocket dumped £30m worth of telecoms kit into the ocean after exploding four minutes into its flight. The cause of the failure was later identified as a fault in the Vulcain engine nozzle's cooling circuit which resulted in the nozzle deforming. This, in turn, sent the rocket off course provoking automatic self-destruct. The Vulcain is the Ariane 5 ECA's main cryogenic engine which is supported by two solid boosters. Atop the main stage is the payload-bearing second stage - itself equipped with a cryogenic engine.

The ESA says it has rectified the problem and has, moreover, given the latest Ariane 5 ECA more muscle than its unfortunate predecessor in the form of increased thrust from both the twin solid boosters and upper cryogenic stage. The maximum payload is estimated at 10 tonnes - impressive, but still three tonnes short of Boeing's Delta 4-Heavy. Nonetheless, the Boeing monster is earmarked for military ops, leaving Ariane a clear run at the civil sector.

Much rests on the success of the mission. "Ariane 5-ECA will be the workhorse of our company, and of the European space industry as well, for the next 10 years," Arianespace's chief Jean Yves Le-Gall told the BBC. "So this launch is very important," he added with a certain degree of understatement. He has some cause for optimism - in 2004 a less potent Ariane 5 "Generic" successfully deployed a six-tonne comms satellite in a morale-boost for the programme. ®

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