NASA Team Investigates an Enhanced Approach for Conducting Tank-to-Tank Transfers of Cryogens for Micro-Gravity Applications

NASA is putting emphases on reusable cryogenic systems to enable returning astronauts to the lunar surface, and eventually on to Mars. Such systems will require replenishing cryogens on-orbit via a cryogenic tanker or propellant depot, and potentially on the lunar and Martian surfaces with the utilization of in-situ resources. Replenishing cryogens on-orbit requires a tank-to-tank transfer which presents challenges due to thermal environments and the absence of gravity. If the transfer process is initiated with the receiving tank empty and at atmospheric temperature, it then must be chilled to cryogenic temperature to enable filling. Likewise, the transfer lines and associated hardware must be prechilled to assure liquid is transferred. Since prechilling results in propellant loss, it is preferred to minimize this process in interest of saving propellant mass. To simplify the operations associated with propellant transfer and explore potential mass savings, NASA has been experimenting with a new methodology which uses a Vented Chill/No-Vent Fill (VC/NVF) approach, and enhances the process using a 3-D printed spray injector augmented with a Thermodynamic Vent System (TVS).