Propellant Mass Gauging: Database of Vehicle Applications and Research and Development Studies

Gauging the mass of propellants in a tank in low gravity is not a straightforward task because of the uncertainty of the liquid configuration in the tank and the possibility of there being more than one ullage bubble. Several concepts for such a low-gravity gauging system have been proposed, and breadboard or flight-like versions have been tested in normal gravity or even in low gravity, but at present, a flight-proven reliable gauging system is not available. NASA desired a database of the gauging techniques used in current and past vehicles during ascent or under settled conditions, and during short coasting (unpowered) periods, for both cryogenic and storable propellants. Past and current research and development efforts on gauging systems that are believed to be applicable in low-gravity conditions were also desired. This report documents the results of that survey.