N° 30–1997: Ariane 502, final steps before launch

16 July 1997

The verification process relating to analysis of the launcher's control loop (see ESA/CNES joint press release of 17 September) has taken longer than expected. Moreover, final qualification of the flight program software will require two additional weeks to complete. For these reasons, the launch campaign for the second Ariane-5 qualification flight at Europe's spaceport in Kourou, French Guiana, is being put on hold from 26 September, aiming at a launch on 15 October 1997 at the earliest. The campaign will be resumed seven days before launch, with the filling of the upper stage.

The Launcher Countdown Rehearsal performed in Kourou earlier in September gave good results. Meanwhile, the qualification process continued in Europe, where computer programs that simulate the real flight conditions of Ariane 502 indicated a risk of oscillation that could increase the consumption of the oil that feeds the displacing actuators used to steer the main engine. To lower the risk of unwanted oscillations on this specific flight, two activities are being conducted in parallel:

a: verification of the validity of the data used in the mathematical model that simulates flight

b: introduction of a corrective measure using a filter to eliminate unwanted oscillations.

Incorporating this filter, contained in an electronic box fitted in the main stage, would entail additional qualification tests that would put the target launch date back by a further one or two weeks.

The choice of course of action and a decision on a new target date for the second test flight of Ariane 5 are expected to be confirmed early in October.