FINAL GALlLEO PROPULSION SYSTEM IN-FLIGHT CHARACTERIZATION

The Galileo Retro-Propulsion performed excellently throughout eight-year Galileo Jupiter mission. state-of-the-art, pressure-fed, propulsion system, provided to Module (RPM) the ambitious, The RPM is a bipropellant NASA by the Federal Republic of Germany. Some Galileo RPM pressure transducers drifted linearly versus time since launch. Consumable usage was generally well within specifications, including propellant usage. Maneuver performance continued to be excellent during the orbital tour of Jupiter. No 1O-N thruster thermal instabilities were observed during the mission, likely due to a conservative, pulsemode operating strategy. Apparent performance shifts of the lateral thrusters were detected and remain unexplained. Nearly all Galileo 1O-N thrusters exceeded ground performance thrust k?VdS by 10/. tO !5Yo. The soft-seat pressure regulator, now isolated, exhibited exemplary performance during the Galileo mission. Conversely, oxidizer and fuel check valve performances were out of specification and highly non-repeatable for the three main 400-N engine burns. However, the 400-N engine performances were only slightly impacted, and a highly successful Jupiter Orbit Insertion and orbital tour were realized.