Long-Term Cryogen Storage Technologies for Orbit Transfer Vehicle

The simplicity of a solar thermal propulsion system offers promise of very low cost compared to advanced cryogenic stages for earth orbit missions. Integrated solar thermal propulsion and power technology has evolved significantly over the past two decadesthrough the combined efforts of government agencies and the aerospace industry. During the past two years, TAI has been developing new insulation and installation techniques, has evaluated aerospace cryocoolers for a long-duration military spaceapplication, and has delivered a cryocooler interface system that can be easily adapted for distributive cooling of storage vessel walls. The main technical objective of this feasibility study is to determine the most cost-effective, reliable, andmass-efficient approach to store cryogenic hydrogen in space for up to ten years. The study will be focused in three key technology areas related to preserving cryogen during long-duration standby modes in LEO or GEO space environments. These areas are:(1) liquid hydrogen storage tank insulation materials and techniques; (2) long-life, high-reliability cryocoolers that have capacity to intercept a large portion of the parasitic heat leak to eliminate boil off; and (3) cryocooler integration issues thatinclude approaches to interfacing the cryocooler(s) with the insulation system and storage vessel. Benefits are methods of zero boil-off feasibility of the insulation system and cryocooler technologies to meet the objectives for on-orbit storage ofcryogenic hydrogen for periods of up to ten years. Potential missions include on-orbit servicing (i.e., refuel, repair, resupply, and upgrade on-orbit assets); reposition space assets; remove orbital debris; assemble large space structures; protectfriendly space assets; survey potentially threatening assets; and disable hostile space assets. Commercial and government space assets that are operational but in useless orbits can be rescued and placed in their intended locations.