FLIGHT PERFORMANCE OF THE SHOOT LIQUID ACQUISITION DEVICES

The Superfluid Helium On-Orbit Transfer (SHOOT) Flight Demonstration, launched on STS-57 in June 1993, demonstrated the technology required for the management and transfer of superfluid helium in low gravity, and was the first orbital experiment using liquid acquisition systems with cryogens. Its primary experimental objective was to test the performance of two different liquid acquisition devices (LADs) which use surface tension forces to gather the liquid and feed it to the superfluid pumps. One system consists of c-channels whose open sides are covered by fine mesh screens which face the tank walls. The other consists of a series of Mylar(TM) Vanes which extend radially from the centre of the tank. Several superfluid transfers were performed during relatively quiescent periods and during two transfers adverse orbiter accelerations of 0.034 and 0.069 m s-2 (3.5 x 10(-3) and 7.0 x 10(-3) g) were generated to move liquid away from the pumps to test the ability of each LAD to work against relatively large hydrostatic heads. Discrete liquid/vapour discriminators placed strategically within the tanks were used to detect failure of the LADs to supply liquid to the pumps. One goal was to test whether, if such a failure occurs, the transfer process can spontaneously recover without operator intervention. Overall performance of both LADs during transfers with and without adverse accelerations is presented.