Analysis of possible early orbit contingencies and recovery strategies for Herschel/Planck

Abstract

Herschel and Planck, the ESA astronomy cornerstone missions, were successfully launched on 2009/5/14 from Kourou on Ariane 5. Herschel, the largest ever infrared telescope, and Planck, to study the cosmic microwave background radiation, were injected together into a nearly parabolic orbit. From there, they were manoeuvred to their operational orbits around the libration point L 2 of the Sun–Earth system: a halo type orbit for Herschel and a small amplitude Lissajous orbit for Planck. Essential to nominal orbit insertion was a correction manoeuvre to be performed within 2 days from launch, to correct for the launcher dispersion, but also other systematic deviations from the required transfer conditions. The present work focuses on the preparation of recovery strategies in case an under-performance of the launcher or a failure to execute the first correction manoeuvre on time had occurred. In a first stage, the limits for extending the nominal orbit design even after an under-performance of the launcher or a delay of the first orbit correction were studied. Furthermore, alternative strategies implying substantial changes to the nominal design were also analysed as a means to recover the science return in case of severe under-performance or failure of the first correction manoeuvre.