FLUG REVUE May 2003: Ariane 4 era ends

ARIANE 4 – THE END OF AN ERA

By Matthias Gründer

Its record of 116 launches with only three mishaps made Ariane 4 one of the most successful commercial launch vehicles ever during the eleven years that it was in service. Ample reason to look back on its history – with a smile and a tear.

Development of the Ariane 4 launch vehicle was the logical continuation of the success story of its forerunners Ariane 1, 2 and 3, of which a total of 28 were launched between 1979 and 1989. During that decade the Arianespace operating company rose to become the market leader in commercial satellite transport, and its owners made it clear that they intended to maintain this lead and even expand it further.

Accordingly, the process of enhancing performance through selective modifications was begun already on the Ariane 1, all of whose stages were modified over time. The impetus for adapting the launcher technology came from the way the satellites to be transported were growing in a somewhat linear fashion by about 100kg per year, and as yet no end to this trend was in sight.

The development programme was launched as early as 1982. Its main elements comprised a lengthening of the first stage and variable installation of liquid gas and/or solid fuel boosters. Combinations of these elements resulted in six different versions of a rocket – almost a new family within the family. Thus, the basic model was the AR 40 without booster and with a 1.9t payload capacity for geostationary transfer orbit (GTO). This was followed by the AR 42P (Ariane 4 with two solid fuel boosters PAP – Propulseurs d'Appoint à Poudres, 2.6t), the AR 44P (four PAPs, 3.0t), the AR 42L (two liquid fuel boosters PAL – Propulseurs d'Appoint à Liquides, 3.2t), the AR 44LP (each with two PALs and PAPs, 3.7t) and the AR 44L with four PALs and a load carrying capacity of 4.21t.

These capacity figures are valid as of the date on which the various vehicles entered service, for the Ariane underwent constant further development and adaptation to changing payloads. The critical factors that made this possible were enlargement of the tanks and optimisation of the mixing ratio of the fuel components of the third stage. As a result, payload capacity for the GTO was increased to 2.07t on the AR 40 and to an incredible 4.9t on the AR 44L.

All Ariane 4 launches were made from the ELA-2 (Ensemble de Lancement Ariane) European spaceport in Kourou. In the earlier ELA-1 complex, from where all the Ariane 1, 2 and 3's had lifted off, the launch vehicles had been assembled, tested, fuelled and launched directly on the ramp. This technology allowed only five launches per year – not sufficient to satisfy the growth in demand expected, especially after the Challenger disaster in January 1986 caused the bottleneck in satellites waiting to be launched to grow ever greater.

The new ELA-2 had two separate zones, one for assembly and control of the launchers and a separate launch zone 950m away equipped with mobile service gantry and fixed umbilical tower. The launch platform also served as transport vehicle between the two zones. In this way the next rocket could be assembled while its predecessor was still on the launchpad, which was officially opened in March 1986 with an Ariane 3. The queue of satellites waiting to be launched then made it necessary to operate both ELAs in parallel for over three years, until Ariane 4 took over all transport jobs on its own.

Other changes that contributed to the success of Ariane 4 were the spacious SPELDA (Structure Porteuse pour Lancement Doubles Ariane) dual launch system and the fact that three different lengths of payload fairing were available. Through skilful combination of these design characteristics, payload utilisation was regularly over 90%, a unique and also cost-effective achievement that benefited the customer.

The high degree of confidence in the launcher is reflected in the award already in February 1989 of a major production order for 50 units, surpassing all previous records. This production batch was actually intended to last through to 1998, but the healthy state of the Arianespace orderbook meant that the launchers were used up faster than planned. As a result, orders were placed for three further production batches for a total of 45 Ariane 4's, but in June 1999 the decision was finally made to terminate production.

In view of Ariane 4's unique success story, with a reliability of 97%, this decision was difficult to understand not just to those involved in building and operating the launch vehicle, who came from all over Europe. Yet at the time the decision no doubt appeared reasonable. On the basis of forecasts made in 1999, future payloads were expected to be either much bigger and heavier than present payloads or else to consist of multiple individual satellites for mobile telecommunication systems. The new, heavy Ariane 5 seemed to be perfectly suited for these missions, and the smaller, flexible Ariane 4 would retire with dignity.

Under these conditions it was not economic to maintain two Europe-wide production lines and two launch complexes in Kourou. No one could foresee then that the forecasts would turn out to be wrong and that Ariane 5 would still not have achieved the necessary reliability even today. Even less could one have guessed that the spaceflight industry would shortly fall into the crisis that still afflicts it today. Meanwhile, Ariane 4 is no more. One should quit when one is riding high. But for the many whose jobs are now in danger this will be of little consolation.

From FLUG REVUE 5/2003

Last updated 7 April 2003

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