Halfway of the Ariane Four-Engine Assembly Showed Power Loss Only Once

Home , Ariane (rocket family), Diamant

Nature Vol. 285 5 June 1980 353 lines at wavelengths greater than 0.8 mm. this loss was detected soon enough to abort an acoustic effect which in turn induced the It will also provide Britain's radioastron the launch. At a subsequent attempt, lift instability. The deflector geometry is omers-whose long lead in radiointerfero off and launch were successful, and the completely different at Kourou from the metry has been broken by the construction earlier fault was put down to instrument geometry adopted in the ground-based of the US Very Large Array- with access error. There may now be doubts about tests. Robert Walgate to at least one world class instrument. whether this was the case. Robert Walgate The Ariane first stage engines are derived from those of an earlier French rocket, Pesticides Ariane 'Diamant' - and this rocket also exper ienced catastrophic losses of power during its development. However, 44 ground tests EEC directive Halfway of the Ariane four-engine assembly showed power loss only once. disputed The fault probably traces back to a fluid to the Devil or chemical instability in the injector, the THE long-standing argument over the 'carburettor' that injects fuel and oxidant basis for environmental standards between EUROPEAN hopes of commercial into the combustion chamber; and the some European governments and the :ompetition with the delayed American question arises whether the instability is European Commission now appears to space shuttle have been called into question triggered by a mechanical fault in the have spread to the consumers' by the failure on 23 May of the second injector, or is simply an inherent instability associations. Thus last week (27 May) the launch test of Ariane, the European three due to a design error. If the latter, a further Consumers' Association, the London stage 1,750 kg payload launcher. The series of ground tests will be necessary based consumer group, published a European Space Agency, responsible for before Ariane's third test flight, and the criticism of the draft directive on the Ariane, has always held that two successful money available for those tests is limited. regulation of pesticides in foodstuffs flights in the four-flight test series (the next Another possibility being considered by originally promulgated in 1976. tests are due in November this year and Ariane engineers is that the geometry of the The CA's argument is based on a February 1981) would be counted a exhaust deflectors at the launch pad led to comparative study carried out in the past success; but what matters is whether three years in West Germany and the UK. potential clients will take the same view. The nub of the issue, according to the They will no doubt now be on their guard. report "Pesticide Residues and Food" The rocket fell into the sea less than 10 (Consumers' Association, 14 Buckingham km from its launch site in Kourou, French Street, London WCZ) is whether the Guyana. It now lies in muddy waters some regulation of pesticides in the human diet is 7 to 10 metres deep between Kourou and the best accomplished by fixing maximum former French penal colony, Devil's concentrations of permissible pesticide Island. Two ships are searching for it, one residues in foodstuffs appearing on the with sonar and the other with drag-nets. If domestic market. the rocket is found, it should be recover The EEC directive proposes that there able. should be maximum permitted levels of The fuel tanks were destroyed by an certain pesticides (particularly the automatic device, but the propulsion bay organocholorines) in foodstuffs, and that - the collection of four combustion it should be the responsibility of national chambers where the critical fault occurred governments to sample foodstuffs - is expected to be intact. It may prove regularly, analysing them for their crucial in determining the cause of the pesticide content. This is for practical accident. purposes the system now in operation in Preliminary analysis of telemetric data West Germany. has revealed that one of the four first stage By contrast, the British system is based engines began to 'flicker' 4.4 sec after on a voluntary scheme for the approval (by ignition, 1.1 sec after lift-off. The pressure the Ministry of Agriculture, Fisheries and in its combustion chamber oscillated at Food on the recommendation of an expert I ,000 Hz with an amplitude of 4 bars about Advisory Committee) of pesticides offered its design pressure of 54 bars, and the for sale in the United Kingdom and on exhaust gases turned yellow, indicating estimates of what foods people eat. The CA inefficient oxidation of the fuel. By 6 joins with other critics of the system in seconds the fault appeared to have urging that the approval scheme should be corrected itself. made statutory, but otherwise comes to the At 28 seconds the fault recurred for an conclusion that this scheme has adequately instant, and then the temperature began to served its purpose of keeping pesticide rise steadily in the propulsion bay from concentrations in human blood and tissues 24°C to 56°C. At 64 seconds the tempera within acceptable limits. ture jumped to 100°C and the combustion One of the CA's chief arguments in chamber pressure dropped to 10 bar. favour of the British system of control is Ariane started to roll. By 104 sec the roll that the German system is much more had reached 10 rpm, and two other engines expensive. But the report, while lost pressure; the third followed at 108 sec. recognising that harmonisation of The self-destruct systems then decided that environmental standards is necessary in the Ariane had had enough, and blew out the interests of European free trade, argues fuel tanks. that it would be inequitable that all A similar loss of pressure was detected members of the EEC should have to adopt just after ignition of the Ariane engines on The Ariane launch, just as the first of the four the most stringent (and cumbersome) of the first launch test in November 1979; but engines began to flicker. the control procedures now in force.