Cryogenic fluid supply from supercritical storage system

A system for providing cryogenic sub-critical liquid oxygen and liquid hydrogen to storage tanks and payloads contained inside the payload bay of a space vehicle is described. The system provides for transferring cryogenic fluid from a supercritical storage tank to a subcritical storage tank or payload in a zero-g environment, wherein the H2 and O2 ignition hazard has been eliminated due to the low vacuum pressure operating environment. The system includes an external heat exchanger, for example, a parallel flow concentric tube design, and a temperature control system for re-condensing the two-phase transfer fluid expelled from the supercritical storage system into a single phase, sub-cooled cryogenic fluid which is then introduced into and stored within the subcritical storage tank.