MESSENGER’S MANEUVERS TO REDUCE ORBITAL PERIOD DURING THE EXTENDED MISSION: ENSURING MAXIMUM USE OF THE BI-PROPELLANT PROPULSION SYSTEM

摘要

Two orbit-correction maneuvers (OCMs) were required during MESSENGER’sextended mission to reduce the orbital period from 11.6 to 8 hours. TheOCMs were designed as a pair to maximize use of the bi-propellant propulsionsystem. The first maneuver was designed to be flexible to a range of values forthe amount of oxidizer remaining in the system. A special autonomy schemewas necessary to respond to oxidizer depletion and continue the maneuverwithout interruption using only monopropellant thrusters. The second maneuverexecuted four days later and was designed on the basis of the performanceof the first maneuver.