An Integrated Vehicle Propulsion and Power System for Long Duration Cryogenic Spaceflight

Abstract

Proposed crewed exploration activities demand that high-performance, cryogenically fueled, inspace stages perform high delta-V missions that range from days to months in duration. Although vehicles such as the Apollo Service Module performed similar missions decades ago they were fundamentally low delta-V and non-cryogenic in nature with only small storage liquid oxygen and hydrogen systems for power generation. Long duration flight of large vehicles containing many tons of liquid hydrogen and oxygen has not yet been demonstrated and many technologies must work together to make this a practical reality. The storage of cryogens for extended periods has been the subject of intensive work with many promising approaches being brought forward. How these propellants are efficiently used in vehicle systems is equally important and equally challenging. For several years United launch Alliance has been developing an integrated system that can extend the present mission durations of existing upper stages from the present twelve hours to the regime of days and weeks. This Integrated Vehicle Fluid system uses some novel methods, some originally conceived in the early 1960’s, to combine power production, attitude control and propellant thermal management to accomplish this goal. It can achieve this while providing a drastic reduction in vehicle dry and total mass and can wholly eliminate toxic propellants and high pressure gases from the vehicle systems. All vehicle functions can be performed using only the hydrogen and oxygen propellants stored in the main propellant tanks. Importantly these technologies can be applied incrementally to first perform post mission experiments, phase in as replacement systems for existing upper stages and ultimately be applied to advanced upper stages such as an Earth Departure Stage. Integrated Vehicle Fluids thus forms a foundational technology for next generation space transport.