By Steve Connor
The European Space Agency has opened an independent inquiry into the failure of the Ariane 5 rocket that shattered into myriad pieces on Wednesday night before splashing into the Atlantic.
Until the results of the investigation are known - which may not be for several weeks - a question mark hangs over the future of Ariane 5, which was seen as the only way for Europe to compete with America and Russia in the potentially lucrative business of launching commercial satellites.
The explosive finale to the latest flight of the Ariane 5 rocket could not have come at a worse time. Because too many rockets are chasing too few payloads, satellite companies may in future be unwilling to entrust their valuable hardware to an "unreliable" launch vehicle.
Out of the 14 launches of the Ariane 5 rocket over the past six years, two have exploded and two have failed to get their satellite payloads into the correct orbit. This 25 percent failure rate compares with an industry standard of about two percent, according to Alan Bond, a rocket scientist at Reaction Engines near Oxford.
"That is a very high rate and Arianespace is going to have to work very hard to regain the confidence of its customers," said Bond.
"It's about the worst possible time for this to have happened. People will think twice before flying their satellites on an unreliable vehicle when there are so many others on the market to choose from." The first hint that something was going dramatically wrong with Wednesday's launch occurred 96 seconds into take-off. Engineers on the launch pad in Kourou, French Guiana, said there was a slight pressure drop in the coolant system to the main Vulcain-2 engine, which should have powered the rocket for the first nine minutes.
After 187 seconds the faring covering the payload was jettisoned as planned, but nine seconds later there was a severe problem within the Vulcain-2 engine. Engineers are not sure whether this was caused by a fault within the engine itself or by something in its immediate vicinity.
Whatever the cause, the result was catastrophic. The launcher fell from an altitude of 93 miles to 43 miles. At a point 455 seconds after take-off, the mission came to an abrupt end when the auto-destruct mechanism blew up the erratically moving rocket.
The two solid-fuel boosters had split off from the main section before the explosion and were parachuted into the ocean. They will now be analysed to see if they can shed light on what went wrong.
Jean-Yves Le Gall, the flight director of the mission, emphasised at a press conference that the latest failure involved a souped-up version of the "classic" Ariane 5. This high-powered version enabled the rocket to carry a 10-ton payload instead of the usual six.
One of the first aims of the investigation is to decide whe-ther the engine problem could also affect the "classic" version of Ariane 5, which is due to launch the Rosetta satellite mission next month to land on a comet. "We have to make sure that Ariane 5 works properly before Rosetta is launched," Le Gall said.
Rosetta is scheduled to be launched on 12 January and any delay will jeopardise the critical launch window that will enable it to fulfil the eight-year journey to the comet Wirtanen. If the satellite is not sent in time, another comet may have to be chosen.
Le Gall said he hoped that the inquiry would give the Rosetta mission the all-clear because of its use of the tried-and-trusted version of the Ariane 5 rocket. He also apologised to the French owners of the two satellites - valued at £400-million - on board the aborted mission.
One of the payloads was an experimental telecommunications satellite and the other was Hot Bird-7, a television satellite owned by Eutelsat. Both were partly insured.
Ariane 5 made its maiden flight in 1996 but that ended in an explosion, this time less than a minute after launch. Its payload was four scientific satellites that made up the Cluster mission to investigate the stream of particles from the Sun. An inquiry concluded that the fault was a computer software error.
Two qualification flights followed before the first commercial launch in December 1999 - which was in fact Europe's biggest and most expensive science satellite, the Newton X Observatory.
There then followed a series of launches that went ahead without any hitch. But last year things began to go wrong again when two missions ended in failure after the rocket failed to get satellites into the required orbits. The setback led to Ariane 5 being grounded for seven months.
Flights finally resumed in February when Ariane 5 successfully launched the Envisat satellite for monitoring the Earth's environment. However, this week's explosion has now put the whole programme back to square one. Any doubts about the reliability of the Ariane 5 rocket will be quickly exploited by its commercial rivals. The American competition takes the shape of Boeing, which has its Delta 4 rocket, and Lockheed and its Atlas rockets. Russia's Proton rocket and even possibly the Long March rockets of China are also contenders to pick up Arianespace's customers.
But the reality is that no one at present is making money by launching satellites. Five years ago there was a surge in satellite demand, driven by an over-enthusiastic expectation for both satellite phones and the dot.com business. Although a new generation of rockets has been developed, few organisation actually want to use them.
In 1997 there were some 60 commercial rocket launches, which fell to 28 last year. This year there will be only 21 commercial satellite launches.
Le Gall said that he was optimistic for the future for Ariane 5 despite the latest setback. But he was under no illusion about the scale of the task facing him and the European Space Agency.
"Our job is difficult," he said. "It's at moments like this that we are cruelly reminded of it. We have already known failures, we will know more."