Superfluid Helium Onorbit Resupply

Replenishment of superfluid helium (SFHe) offers the potential for extending the onorbit life of observatories, satellite instruments, sensors, and laboratories which operate in the 2 K temperature regime. We have completed studies to define requirements for SFHe resupply and develop a conceptual design for a superfluid helium tanker (SFHT). A reference set of resupply customers was identified as representing realistic helium servicing requirements and interfaces for the first 10 years of superfluid helium tanker (SFHT) operations. A mixed fleet approach was considered with the SFHT compatible with launch on the STS as well as Delta, Atlas, Titan III or Titan IV launch vehicles. The tanker design provides for servicing from the shuttle cargo bay, in situ when attached to the OMV and carried to the user spacecraft, and as a depot at Space Station Freedom. Our SFHT design uses a conventional dewar approach with multiple vapor cooled shields, and the porous plug phase separator is used for onorbit temperature control. An open loop refrigeration approach was used for ground conversion of normal helium as loaded to SFHe, permitting near total fill of the supply tank. Component redundancy meets fail-operational and fail-safe requirements, and the tanker is designed to meet a 50 mission life requirement.