It was designed to be the most reliable rocket launcher ever built. Before the flight of the Ariane 5 on June 4, officials at the European Space Agency (ESA) boasted that, based on statistical calculations, they had trimmed the chance of failure to 1.5%--or 1 out of 70 launches. But the overconfident promise tempted fate. Thirty seconds after blastoff, the unmanned launcher, developed at a cost of $7.8 billion, jerked mysteriously off course, broke apart, and finally exploded, destroying four scientific satellites worth $500 million, belonging to the ESA. It was the biggest space disaster in European history.
What went wrong? On July 23, an inquiry board formed by the ESA and the French Space Agency--the prime contractor for the Ariane launcher--revealed that human errors in management and testing, not mechanical failure, were the main cause behind the explosion. The findings underscore the risk of cutting corners in engineering and preflight testing as competition in the $3 billion global market for commercial space launches heats up.
The problems began when Aerospatiale, the industrial architect of Ariane, and subcontractors Matra Marconi Space and Sextant Avionique left some software used in the previous generation of the launcher, the Ariane 4, unchanged in Ariane 5. The software is designed to position the rocket shortly before liftoff and align the trajectory for 40 seconds into the flight. The function was unnecessary, but it was left untouched because no one imagined it would cause a malfunction in Ariane 5. The software "worked perfectly on Ariane 4, so we decided not to tamper with it," says Jacques Durand, head of the Ariane 5 program at the European Space Agency.
The result: When Ariane 5 lifted off from the Guiana Space Center in Kourou, its flight path did not correspond to data stored in the rocket's system for the correct launch of an Ariane 4. The faulty comparative data caused the 740-ton rocket to veer abruptly off course, breaking the boosters and triggering an onboard detonation system that blew up the rocket. The entire sequence of events took place within two seconds.
The ESA is overhauling Ariane 5`s software systems and preflight testing procedures for software. From now on, Aerospatiale will be responsible for testing each item of equipment with embedded software and certifying the software's correct performance.
Space program experts concede that technological mishaps such as the one that doomed the Ariane 5 are common when the first of a new series of rockets is tested. "It's the nature of the business," says one NASA official, who describes the Ariane launchers as highly competitive.
But the six-month delay expected before the next Ariane 5 launch casts a shadow over Europe's aspirations to remain the global leader in commercial space launches. Europe now holds a 50% share of the $3 billion-a-year market, but competition from Russian, U.S., Japanese, and Chinese companies is heating up. "The main challenge they have is being squeezed by less expensive Russian and Chinese rockets, and by the new American launch vehicles down the road," says John E. Pike, director of the space policy project at the Federation of American Scientists. The June explosion already is expected to boost the total cost of the Ariane 5 project by as much as 4%, or $300 million, which could prompt the European Space Agency to scale back some of its projects later this year.
COMPETITIVE ERA. Worse, Ariane's backers are beginning to realize that their 10-year-old strategy of building Ariane 5 as a bigger launcher may be intrinsically flawed. The market for launching smaller, low-orbiting communications satellites, like the 66 planned for the Motorola Inc.-backed Iridium satellite communication system, is taking off.
The ESA will no doubt recover from the Ariane 5 debacle. Solving technical problems like faulty software after the fact is easy, and two successful Ariane 4 launches have taken place since the mishap. But a new competitive era is dawning, and ESA will have to fight harder than ever to retain its commanding market share. In that climate, the kind of conceit that led engineers to assume Ariane 5's software didn't need testing could trip up ESA on the ground as well.