The current concept of hqutd hehum resupply from the space stat=on ts discussed wtth regard to user and space statton requ=rements, as well as requ=rements of the hqutd hehum servicing facfltty ttself A number of trade-offs which will affect both the hardware and the operatton of the fac=llty are presented A total of 12 potenttal users have been ~dent=fied The users are d~v~ded into two groups large volume users whtch are servtced every one to two years and small volume users wh=ch are serwced every few months Both groups have a very strong tmpact on the defmttton of the hqutd hehum servtcmg factltty The facdtty components will be based on results of the SuperfluJd Hehum On Orbit Transfer fhght demonstration being conducted by NASA Currently, the space stahon des=gn includes a customer servicing bay whtch prov0des electrtcal power, thermal and contammatton control, and connecttons for control and data handhng systems Restrtcttons on venting and vtbrat=onal dtsturbances on the space stat=on may preclude serv=cmg during qutescent per=ods when accelerahons are minimal
Keywords hel,um, hehum transfer, space cryogen,cs
The Advanced X-ray Astrophysics Facility (AXAF), Space Infrared Telescope Facility (SIRTF), Astromag and similar facilities all depend on the low temperatures which can only be provided by liquid helium A liquid helium servicing facility (LHSF) located on the space station could extend the lifetime of these and other facilities from one to three to ten years or more The dewars for these facilities will maintain the helium for between one and three years At that time, the helium must be replenished for the faclhty to continue operating Although xt will be possible to perform liquid helium servicing from the space shuttle, servicing on the space station offers some advantages The space station will include a Customer Servicing Facility (CSF) which will provide a protected environment for the replenishment of consumables and for instrument change-out and repair In addition, the CSF will provide thermal and power accommodations, contamination control, and connections for data handhng and control systems Another advantage is the virtually unlimited mission hfe of the space station The shuttle has a maximum operational mission length of seven days Any major delays m servicing could result in an unfilled or parhally filled dewar, or unfinished equipment repairs In that case, the payload would be returned to orbit for serwclng at a later time or the shuttle would return with it to earth for ground serwclng and relaunch *Paper presented at the Space Cryogentcs Workshop, Mad=son,