SpaceDev Inc. is proposing an innovative fluid coupling enabling the transfer of consumables such as liquid oxygen while maintaining functionality in the presence of lunar regolith, including dust. SpaceDev initially designed and developed this coupler to support on-orbit fluid transfer of cryogenics, gases, and water. Further development of and enhancements to this existing design are planned under Phase 1 to demonstrate feasibility for lunar applications, with advanced prototype testing in Phase 2 to make-ready the coupling for formal flight qualification and production. At the heart of the fluid coupling is an innovative re-settable knife edge seal that requires low pre-loads to provide the fluid seal. The sealing surface can be quickly and easily reset with the application of a heater-type electric signal for only a few minutes at ambient conditions. Joint coupling is accomplished by a sharp-edged member piercing and embedding itself into a soft Indium seal ring. After coupling disconnect, reset is accomplished by heating the Indium seal to its melting point. Entrained in an arterial wick, the seal ring surface reflows, leaving a virgin seal surface upon cooling. The arterial wick allows for joint reflow in microgravity environments. The coupling is then reset to allow for successive servicing operations. Current prototypes have been tested with air, water and LN2 at pressures from 0 to 100 psi. SpaceDev recently completed a separate Phase 1 SBIR that demonstrated that the all-metal, knife-edge seal con-cept has the capability for maintaining seal integrity even in the presence of the abrasive, lunar dust. The knife edge seal offers two distinct advantages when attempting to mitigate the affects of lunar dust: 1) the knife edge tends toward self-cleaning and exclusion of foreign matter such as lunar dust due to metal cold-flow patterns during penetration, and 2) the Indium can be heated and re-flowed in between mate and demate cycles to reform a fresh seal.
