Abstract
Knowledge of location of the ullage, the gas pocket within a liquid propellant tank, and ullage dynamics is of vital importance to deep-space refueling depots. Characterizing the size and location of the ullage within liquid propellant tanks in equilibrium is crucial to the Mars mission. An experiment payload was designed to test a method of gauging the size and location of the ullage within a liquid propellant tank. Broadband white noise is passed into a stainless steel tank filled with a rocket propellant simulant. The acoustic vibrations are measured at several point sensor locations along the surface where changes in amplitude are representative of changes in the thickness of the liquid layer coating the inside of the tank. The data suggests that the sensors are able to detect the passage of the liquid surface under the effect of gravity but are not accurate enough for space flight at the moment.
