NASA’s progress maturing zero boil-off technology to enable long-duration space missions with cryogenic propellants

Abstract Storing cryogenic propellants in space from months to multiple years duration and transfer of these propellants from one tank to another (refueling) are signi9icant challenges on the critical path for returning humans to the moon, future Mars missions, and commercialization of cis-lunar space. State-of-the-art storage duration for operational cryogenic stages is currently less than a day; cryogenic propellant transfer in space has never been demonstrated. NASA and its partners have studied solving the storage duration challenge through the integration of refrigeration technology with the propellant system, so-called Zero Boil-Off (ZBO) technologies, for many decades. The feasibility of ZBO propellant storage in space has been shown to a reasonable degree of con9idence; what remains are tasks to enable design with acceptable margins while optimizing the system performance.