Estimation of propellant remaining in a satellite

摘要

An amount of propellant remaining in an orbiting satellite can be estimated in a more accurate manner than is possible with conventional approached. Pressure and temperature telemetry data received from the satellite can be analyzed using a maximum likelihood estimation approach that reconstructs a predicted tank pressure signal using the temperature data and determines a pressurant volume necessary to make the reconstructed pressure signal match the received pressure signal. Drift of the pressure data received from pressure transducers in the satellite can also be addressed using the current subject matter, as can issues including but not limited to inaccessible propellant due to satellite spin, tank expansion under pressure, and the like. Independent determinations of the amounts of propellant remaining can be made using moment of inertia calculations in situations in which an axis of spin of the satellite is known a priori.

主权项

1. A computer-implemented method comprising:
receiving pressure telemetry data and pressurant temperature telemetry data for a propellant tank of a satellite over a time interval, the propellant tank having a known geometry and containing an amount of propellant and a volume of a gas-phase pressurant, a rate of propellant consumption in support of satellite operations over the interval being sufficiently small to create a quasi-isochoric condition for the pressurant over the time interval such that an actual pressure in the propellant tank is proportional to an actual pressurant temperature in the propellant tank over the time interval; calculating a metric relating the volume of the pressurant, the pressure telemetry data and the pressurant temperature telemetry data, the metric calculation comprising reconstructing, based on the received pressurant temperature telemetry data, a predicted set of pressure data for the time interval and comparing the predicted set of pressure data to at least part of the pressure telemetry data, the reconstructing comprising assuming a direct proportionality between the predicted set of pressure data and the pressurant temperature telemetry data; solving for a most likely estimate of the volume of the pressurant to optimize the metric; and determining, based on the most likely estimate of the volume of the pressurant and the known geometry of the propellant tank, the most likely amount of propellant remaining in the propellant tank; wherein the receiving, calculating, solving and determining are performed by at least one system comprising computer hardware.