Orbital resupply of liquid helium

The ability to resupply scientific instruments in orbit with liquid helium would greatly enhance several planned missions. These missions include the SIRTF (Space Infrared Telescope Facility), the LDR (Large Deployable Reflector), the GP-B (Gravity Probe - B), and include individual instruments on the HST (Hubble Space Telescope), and on the AXAF (Advanced X-ray Astrophysics Facility). Resupply in orbit would extend the lifetimes of these missions without the difficulties, the delays, and the costs that are associated with retrieving the system, resupplying these systems on the ground, and relaunching. This is especially true of systems, such as the LDR, that are assembled in space and thus would be difficult to return to earth. This paper presents a conceptual design of a Helium Resupply System (HERS) and a discussion of the transfer efficiency.