Planned axial reorientation investigation on Sloshsat

This paper details the design and logic of anexperimental investigation to study axial reorientationin low gravity. The Sloshsat free-flyer is described.The planned axial reorientation experiments and testmatrixes are presented. Existing analytical tools arediscussed. Estimates for settling range from 64 to1127 seconds. The planned experiments are modelledusing computational fluid dynamics. These modelsshow promise in reducing settling estimates anddemonstrate the ability of pulsed high thrust settling toemulate lower thrust continuous firing. INTRODUCTION The European Space Agency (ESA) in conjunctionwith the Netherlands Agency for Aerospace Programshas undertaken a project to investigate fluid motion inzero-g. ESA has contracted with the NetherlandsNational Aerospace Laboratory (Nationaal Lucht-enRuimtevaartlaboratorium or NLR) for a small freeflying spacecraft deployed from the shuttle but flying intandem with it. This spacecraft is known as theSloshsat Facility for Liquid Experimentation andVerification On-orbit (Sloshsat FLEVO or justSloshsat for short). The ESA/NLR investigators haveconcentrated on studying the effect of liquid motions onspinning spacecraft. NASA has spent several yearsinvestigating the low gravity maneuvers to settlepropellants prior to restarting engines in space after alow gravity coast. These maneuvers involve using anaxial thrust to create a simulated gravity forcing thepropellant to the "bottom" of the tank. Although thesemaneuvers have been extensively studied indrop-towers and by analysis, little flight data exists.Sloshsat is an ideal platform to obtain the long termlow-gravity data necessary to confirm the findings ofthe analytical work and drop tower tests. This paperwill discus the experiments planned for Sloshsat tostudy these maneuvers.