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Flight 157- Ariane 5 ECA Press Conference Paris - January 7, 2003

Flight 157- Ariane 5 ECA Press Conference Paris - January 7, 2003. Flight 157- Ariane 5 ECA Rencontre avec la Presse Paris - mardi 7 janvier 2003 . Recap of events. Wednesday, December 11: Flight 157- Ariane 5 ECA

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Flight 157- Ariane 5 ECA Press Conference Paris - January 7, 2003

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  1. Flight 157- Ariane 5 ECA Press Conference Paris - January 7, 2003 Flight 157- Ariane 5 ECA Rencontre avec la Presse Paris - mardi 7 janvier 2003

  2. Recap of events • Wednesday, December 11: Flight 157- Ariane 5 ECA • Friday, December 13: appointment of Inquiry Board and Technical Experts task group • Monday, December 16: Beginning of inquiry • Wednesday, December 18: Visit to SNECMA (Vernon) • Monday, December 23: Interim report • Friday, December 27: Visit to VOLVO (Trolhattan) • Saturday, December 28: Meeting of partners • Monday, January 6: Final report Flight 157- Ariane 5 ECA Rencontre avec la Presse Paris - mardi 7 janvier 2003

  3. Flight 157- Ariane 5 ECA Report of the Inquiry Board Paris - January 7, 2003

  4. Contents • Duties of Inquiry Board • Description of Flight 157 - Ariane 5 ECA • View of Vulcain 2 engine • Vulcain 2 engine • Views of Vulcain 1 and Vulcain 2 • Most probable cause of Flight 157 failure • Consequences for Ariane 5 Baseline • Consequences for Ariane 5 ECA

  5. Duties of Inquiry Board Following the anomaly observed during Flight 157 on Wednesday, December 11, Arianespace decided -- in cooperation with the European Space Agency and French space agency CNES -- to create an inquiry board with the following duties: • Establish the causes of the anomaly observed during Flight 157 - Ariane 5 ECA (the "10-ton" Ariane 5), • Determine the eventual consequences of the anomaly on operations of basic Ariane 5 versions, in particular on preparations for the upcoming launch with the Rosetta deep space probe, • Recommend measures to be taken to correct the problems observed.

  6. Description of Flight 157- Ariane 5 ECA • The synchronized sequence, the firing of the Vulcain engine and the ignition of the solid boosters were nominal. • The launcher’s flight was nominal until the separation of the solid boosters (T + 137 seconds). However, during this phase an anomaly on the Vulcain 2 engine appeared: there was a pressure drop at the “dump cooling” outlet, characteristic of a leak in the nozzle cooling system. • At about T + 170 seconds there was a rapid degradation of cooling of the nozzle resulting in functional loss and leading to overheating of the nozzle, followed by loss of the nozzle’s integrity. • This resulted in a major imbalance in the thrust of the Vulcain 2 engine, leading to a loss of control over the launcher’s trajectory.

  7. View of the Vulcain 2 engine

  8. Vulcain 2 engine • In comparison with the Vulcain 1 engine (Ariane 5 Baseline), the Vulcain 2 engine (Ariane 5 ECA) offers about 20% more thrust, contributing to an increase in the launcher payload (10 tons for Ariane 5 ECA, compared with 7 tons for the Ariane 5 Baseline) • This increase in thrust has been achieved by: • increasing the pressure in the combustion chamber and using a different mix ratio (more liquid oxygen) • increasing the area ratio (nozzle/throat) from 45 to 60 • reinjection of exhaust gases from the turbopumps in the nozzle. • These modifications resulted in: • higher heat flux • a longer nozzle with a wider diameter

  9. Views of Vulcain 1 and Vulcain 2 Vulcain 1 Vulcain 2

  10. Most probable cause of Flight 157 failure • The mechanical resistance of the engine was carefully checked during qualification tests at Vernon and Lampoldshausen • During the flight, the engine is subjected to loads that cannot be simulated during ground qualification tests • The resistence of the engine to the loads observed in flight can only be qualified by modeling. • Consequently, the most probable cause of the failure of Flight 157 is the simultaneous occurrence of two aggravating factors: • The degrated thermal condition of the nozzle due to cracks in the cooling tubes, resulting in the leaks observed, and • Non-exhaustive definition of the design loads, combined with a combination of various stress factors during the flight.

  11. Consequences for the Ariane 5 Baseline • The designs of the nozzles on the Vulcain 1 and Vulcain 2 engines differ in two main ways: • The shape of the cooling tubes, which form the structure of the nozzle, and • The technology of the nozzle’s stiffeners. • In-flight performance of the Vulcain 1 engine (12 successful flights) did not identify any weaknesses concerning the functioning and resistance of its nozzle. The Inquiry Board nevertheless requested an exhaustive examination of the behavior of the Vulcain 1 engine nozzle, including precise modeling to demonstrate the correct behavior of the nozzle during flight. These checks are currently in progress.

  12. Consequences for Ariane 5 ECA The Inquiry Board requested that the following actions be taken: • Modification of the Vulcain 2 nozzle, taking into account experience acquired with the Vulcain 1 engine nozzle, • Assessment of possibilities for simulation during ground tests of loads observed during actual flight on the Vulcain 2 engine, and • Enhancing the quality of flight-standard equipment.

  13. Next steps • Ariane 5 Baseline: verification of the Vulcain 1 engine is in progress. • Ariane 5 ECA: based on the recommendations made by the Inquiry Board, Arianespace will announce a plan on Monday, January 20 for resumption of flights. The objective is the next flight within 6 months. • Rosetta (Ariane 5 Baseline): • Creation of a Review Board to assess specific factors involved in the Rosetta flight. • Decision on Tuesday, January 14 • Other launches • Feburary 11: Ariane 4 • 2nd half of February: Ariane 5 Baseline Flight 157- Ariane 5 ECA Rencontre avec la Presse Paris - mardi 7 janvier 2003

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