ARIANE 5 SHOCK ENVIRONMENT QUALIFICATION FOR AN EARTHOBSERVATION SATELLITE

摘要

Shock environment induced by new generation launchers can be dimensioning for payload sensitive unit. Recent developments led to reduce significantly VEB separation shocks on Ariane 5 and fairing separation becomes the only shock to take into account.Predictions of shock levels at unit interface are necessary to verify that all satellite unit withstand the launcher shock environment. Using simulations to predict shock levels inside the satellite, remains difficult because the shock propagation is very complicated with a wide frequency band, different propagation paths and various influent parameters.In Ihe case of the HELIOS IIA satellite, shock predictions were based on SHOGUN (Shock Generation Unit) test results and on the specification at Ihe satellite interface, provided by ARIANESPACE. This SHOGUN test was realized in June 2000, on Ihe structural and thermal model of the satellite platform. These shock predictions, at unit level, were compared to qualification status of each unit (random test and shock tests on flight models).First analysis demonstrated that many platform unit were not qualified to the predicted shock levels, especially in the low frequency band. So, it was decided to develop a launcher attenuator, called MFD-C, to reduce the shock environment at satellite interface level. A shock test campaign was performed at EADS CASA to evaluate the performance of the attenuator itself and the attenuation obtained for the complete launch configuration. For these SHOGUN tests, the payload used was the SPOT1 engineering model platform, to be representative of the specific satellite interface.New predictions of shock levels at the satellite interface were performed, taking into account the results obtained with the MFD-C attenuator and the latest Ariane 5 flights measurements. Most of these predicted shock levels were covered by qualification tests realized on unit flight models.The conclusion was that all the satellite unit were qualified with respect to the launch shock environment.