FLUG REVUE April 2002: Ariane 5 launches again after modifications

ARIANESPACE ANXIOUS TO RE-LAUNCH ARIANE 5

By Matthias Gründer

To speak of a crisis at the European launch service provider Arianespace would probably be an exaggeration. After all, 66 Ariane 4 launch vehicles have been successfully launched into space since March 1995. In a total of 146 launches, 194 satellites have been placed in orbit and in 2001 Arianespace maintained its leading position in the commercial satellite transport business: 13 out of 25 launch contracts signed around the world have gone to the Europeans, and the orderbook is looking extremely healthy with 51 payloads to be launched.

Yet there is no getting around the fact that the successes achieved in the launch business have largely rested on the shoulders of the tried and tested Ariane 4. But that model is being phased out, and it is expected that the last example will lift off in April 2003. After that the bigger Ariane 5 will be the sole "workhorse” of the company, with ten launches a year from two parallel launch frames.

Yet the process of transitioning to the new Ariane version has not exactly been trouble-free. 2001 was the second year in a row that Arianespace finished in the red, recording a net loss of some Euro 50 million as a result of the failed launch of Ariane 510 in July. The previous year it had posted losses of Euro 242 million on a turnover of Euro1.1 billion. After the problems of 2001, sales dropped back to only Euro 800 million. Nevertheless, Arianespace Chairman and CEO Jean-Marie Luton expects to break even in 2002.

Luton's optimism is guarded, but is probably not without foundation, as in a concerted campaign politicians, scientists and engineers in design bureaux, test facilities and supplier companies have all been pulling out the stops in recent months to ensure that the name Ariane continues to stand for safety and reliability in the future.

For example, substantial progress has been made on increasing competitiveness in the technical and industrial areas: Arianespace's new S5 payload complex in Kourou is the most modern facility of this type in the world, enabling four launch campaigns to be carried out simultaneously. The launching installations have also been modernised and are now capable of handling the new ESC-A upper stage. This will be employed for the first time in 2002, increasing the payload capacity of the launch system to ten tonnes for geostationary orbit.

Just for operations in Kourou, the research ministers of the ESA member states have approved Euro 423 million of funding up to 2006, while other huge sums are flowing into the infrastructure and technology programme for further development of the rocket. A new corporate structure is also being implemented with the aim of putting the Ariane programme on an industrial basis in the future. How soon the technical efforts can generate fresh marketing successes will depend on rapid results in this area.

However, all these activities are just the outer framework for the campaign for a stable market presence. This depends critically on the launch system operating reliably. The aim is ultimately to achieve 98.6% reliability. The rocket is currently far short of this goal – two failures in ten launches was simply too many.

The risk of unsuccessful launches is not only driving up the cost of insurance premiums for the satellites but sooner or later it will push the satellite operators into the arms of the competition in the launcher market, as they can only earn money if their satellites are positioned in the right location at the right time. And Arianespace itself will only start making a profit when the rocket finally achieves the desired degree of reliable operation.

Ariane stage

For this reason, in recent months since the tragic flight AR 510/V-142, engineers have been working around the clock, especially at Astrium's Bremen site as it is there that the upper stage, whose malfunction led to the loss of a communications satellite in July 2001, is built. An extensive test and analysis programme was launched immediately after the mishap to identify the cause of the failure. This proved a veritable detective puzzle as it was not clear from the transmitted data where the search should start.

Some 200 hot tests of the upper stage engine Aestus were carried out jointly with the German Aerospace Centre (DLR) at the Lampoldshausen site, under all conceivable conditions until finally the most likely causes were identified: apparently some fuel lines had been contaminated with water that may have developed as a result of condensation in the tropical climate of Kourou. However, there was no way of achieving 100% certainty as it was not possible to examine the malfunctioning engine directly.

A host of technical modifications were made as a result of the tests, the most important of which were described as follows by Horst Holsten, head of Transport Systems at Astrium and leader of the 100-strong team of experts. "Essentially we have made the ignition sequence "softer” by flooding the lines to the engine with helium prior to ignition. We will also be able to monitor the pressure ratios in the tanks during the flight through to ignition of the upper stage engine. And finally, even before that, we are introducing a new procedure on the ground that will eliminate the formation of water in the lines even in the tropical climate of Kourou.”

The technicians have thus done everything humanly possible to get Ariane 5 back into the air. All slack in the scheduled has been used for testing and deliberating, and, to save time, the modified upper stage has even been transported to the launch pad by a different means than the normal sea transport.

On 1 February 2002, a Ukrainian Antonov An 124-100 landed in Bremen to fly the precious cargo to Kourou. There it was integrated with the main stage between 4 and 25 February ready for the launch of AR 511 with Europe's environmental satellite Envisat, the heaviest and biggest spacecraft ever to be transported into space by a commercial rocket.

Delivery any later would have jeopardised the launch calendar for 2002, as a minimum of twelve flights are scheduled for this year, five of them alone using Ariane 5. The competition will once again be watching with interest.

From page 44 of FLUG REVUE 4/2002

Last updated 8 March 2002

FLUG REVUE, Ubierstr. 83, 53173 Bonn, Germany