TIM FURNISS / LONDON
Investigations continue into why two satellites failed to reach their correct orbit
The independent inquiry board investigating the failure of Flight V142, an Ariane 5G launch on 12 July to place two satellites into the correct orbit, plans to make its initial report on 1 August.
Further Ariane 5 flights are on hold awaiting any corrective measures that may be required and some payloads could be transferred to Ariane 4s.
Arianespace operations of the smaller Ariane 44L launcher will continue, the launch of Flight V143 carrying Intelsat 902 on 23 August being the next planned.
Preliminary analysis of Flight V142 indicates a leak at the start of the burn from one of the two tanks storing hypergolic propellants in the EPS upper stage, which is powered by a 6,500lb thrust (29kN) Astrium-built Aestus engine.
This is likely to have caused an 80% reduction in thrust and a premature shutdown 80s too early, resulting in the Artemis and BSAT-B2A satellites being placed into the wrong transfer orbits.
Artemis, the costliest communications and navigation satellite ever launched by the European Space Agency, is now in an orbit of 17,545 x 594km (11,000 x 370miles), with a 2.9í inclination. The Japanese BSAT-2B communications spacecraft is in a 17,472 x 592km orbit also at 2.9í inclination. The planned orbit was 35,853 x 858km, 2í inclined geostationary transfer orbit (GTO) for both.
Although the satellites are valued at a combined $1 billion, with Artemis alone estimated to cost $850 million, they were reported to have been insured for only $111 million: $63 million for BSAT and $48 million for Artemis.
V142 was the 10th flight of the Ariane 5, which had previously experienced one total failure on its first flight in 1996 and a partial failure on the second flight in 1997. All other flights were successful prior to this orbital failure.
The Orbital Sciences-built BSAT-2B satellite, intended as an in-orbit back-up to the BSAT-2A launched on an Ariane 5 in March, is likely to be classed as a total loss.
Its apogee engine, designed to circularise the GTO to a geostationary (GEO) orbit, cannot be shut down and restarted to allow the phased number of burns needed to raise the orbit.
The ESA's Artemis spacecraft may, however, be capable of reaching GEO using its restartable liquid apogee engine, thrusters and an experimental ion propulsion system. Options for a mission in the existing orbit are being studied.
Source: Flight International
