Atlas Centaur Extensibility to Long-Duration In-Space Applications

Abstract

is pursuing Centaur derivatives that will provide a common-stage supporting launch vehicle, upper-stage-applications, and the in-space/ascent/descent longduration needs. Lockheed Martin's common-stage concept would provide efficient, robust in-space transportation, and take advantage of the high-mass fraction that is enabled by Centaur's moncoque design and its common bulkhead to minimize combined LO 2 /LH 2 boil off. Lunar exploration missions that take advantage of the high Specific Impulse (sec) (ISP) of LO 2 /LH 2 propulsion for in-space transportation have initial mass-to-orbit launch requirements less than half of those using traditional storable propulsion stages. Therefore, the application of long-duration LO 2 /LH 2 in-space propulsion technology will result in significant launch cost savings for space exploration. We would achieve passive longduration capability by implementing cross cutting Cryogenic Operation for Long Duration (COLD) technologies, and improve cryogenic storage capability by more than two orders of magnitude compared to existing large-scale flight-proven systems. Using a common stage for launch-vehicle upper stage and in-space operations reduces development and recurring costs while providing the high-flight rate needed to achieve the demonstrated high reliability required for crewed space exploration.

Modular Space Vehicle Architecture for Human Exploration of Mars Using Artificial Gravity and Mini-Magnetosphere Crew Radiation Shield

“…To enable the long duration mission required for the MTS, Centaur's thermal protection system will have to be substantially enhanced, reducing boil-off by a factor of 100, 13 while not adding substantial weight, as shown in Fig. 19.…”

A Practical, Affordable Cryogenic Propellant Depot Based on ULA's Flight Experience

“…A recent study 20,21 on the Centaur indicates how robust passive long term LO2/LH2 storage can be accomplished, figure 10.…”

Parahydrogen–Orthohydrogen Conversion for Enhanced Vapor-Cooled Shielding of Liquid Oxygen Tanks

“…Recent cryogenic propellant projects, including the Cryogenic Orbital Test Bed [6] and Advanced Cryogenic Evolved Stage [7], use hydrogen boil-off in a vapor-cooled shield to minimize boil-off from the LO 2 tank. The normal boiling points of LH 2 and LO 2 are 20.271 and 90.188 K, respectively, at atmospheric pressure.…”

“…Boil-off vapor from the lower temperature and lighter LH 2 can be used to completely eliminate boil-off of the heavier, and therefore more valuable, LO 2 . For many short-duration missions, this is sufficient for mitigating the costs of fuel loss; however, if humans aspire to travel to and from neighboring planets or asteroids, boil-off mass flow rates less than 0.01% per day are required [6]. Although significant advances to active cooling technologies are being made, the systems remain substantial mass and power encumbrances to a spacecraft at this time.…”