대표
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1. A computer-implemented method comprising: receiving pressure telemetry data and 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 pressurant;calculating a metric relating the volume of the pressurant, the pressure telemetry data and the temperature telemetry data, the metric calculation comprising reconstructing, based on the received temperature telemetry data, a predicted set of pressure data for the time interval ...
1. A computer-implemented method comprising: receiving pressure telemetry data and 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 pressurant;calculating a metric relating the volume of the pressurant, the pressure telemetry data and the temperature telemetry data, the metric calculation comprising reconstructing, based on the received 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, and wherein reconstructing comprises assuming a direct proportionality between the predicted set of pressure data and the temperature telemetry data;solving for a most likely estimate of the volume of the pressurant to optimize the metric;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; andwherein the receiving, calculating, solving and determining are performed by at least one system comprising at least one programmable processor. 2. A computer-implemented method as in claim 1, further comprising commanding that the satellite operate a valve isolation system to isolate the propellant tank. 3. A computer-implemented method as in claim 2, further comprising: detecting, over the time interval, that the most likely estimate of the volume of the pressurant is not constant; anddetermining, for the time interval, a drift rate of a pressure transducer associated with a pressure transducer on the satellite that generates at least part of the pressure telemetry data, the drift rate being determined to account for the detected non-constant volume. 4. A computer-implemented method as in claim 2, further comprising: commanding that the satellite de-isolate the propellant tank and isolate the second propellant tank for a second time interval, the second propellant tank having a second known geometry and containing a second amount of propellant and a second volume of the pressurant;receiving second pressure telemetry data and second temperature telemetry data for the second isolated propellant tank;calculating a second metric relating the second volume of the pressurant, the second pressure telemetry data and the second temperature telemetry data, the second metric calculation comprising reconstructing, based on the received second temperature telemetry data, a second predicted set of pressure data for the time interval and comparing the second predicted set of pressure data to the second pressure telemetry data;solving for a second most likely estimate of the second volume of the pressurant to optimize the second metric; anddetermining, based on the second most likely estimate of the second volume of the pressurant and the second known geometry of the second propellant tank, the most likely second amount of propellant remaining in the second propellant tank. 5. A computer-implemented method as in claim 1, further comprising: determining an amount of inaccessible propellant in the propellant tank, the determining of the amount of inaccessible propellant comprising estimating a location of a spin axis of the satellite based on an estimation of the moment of inertia of the satellite using on-orbit telemetry data, and estimating a distance from the spin axis to a center of a propellant tank. 6. A computer-implemented method as in claim 5, wherein the estimating of the location of the spin axis of the satellite comprises observing a change in the moment of inertia of the satellite in response to a known amount of consumed propellant. 7. A computer-implemented method as in claim 1, wherein the calculating further comprises correlating the pressure telemetry data and temperature telemetry data in at least part of the time interval. 8. A computer-implemented method as in claim 1, wherein at least one of the commanding, the receiving, the calculating, the solving, and the determining is performed by a system comprising at least one programmable processor. 9. A system comprising: at least one programmable processor; anda machine-readable medium storing instructions that, when executed by the at least one programmable processor, cause the at least one programmable processor to perform operations comprising:receiving pressure telemetry data and 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 pressurant;calculating a metric relating the volume of the pressurant, the pressure telemetry data and the temperature telemetry data, the metric calculation comprising reconstructing, based on the received 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, and wherein reconstructing comprises assuming a direct proportionality between the predicted set of pressure data and the temperature telemetry data;solving for a most likely estimate of the volume of the pressurant to optimize the metric; anddetermining, 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. 10. A system as in claim 9, wherein the operations further comprise commanding that the satellite operate a valve isolation system to isolate the propellant tank. 11. A system as in claim 10, wherein the operations further comprise: detecting, over the time interval, that the most likely estimate of the volume of the pressurant is not constant; anddetermining, for the time interval, a drift rate of a pressure transducer associated with a pressure transducer on the satellite that generates at least part of the pressure telemetry data, the drift rate being determined to account for the detected non-constant volume. 12. A system as in claim 10, wherein the operations further comprise: commanding that the satellite de-isolate the propellant tank and isolate the second propellant tank for a second time interval, the second propellant tank having a second known geometry and containing a second amount of propellant and a second volume of the pressurant;receiving second pressure telemetry data and second temperature telemetry data for the second isolated propellant tank;calculating a second metric relating the second volume of the pressurant, the second pressure telemetry data and the second temperature telemetry data, the second metric calculation comprising reconstructing, based on the received second temperature telemetry data, a second predicted set of pressure data for the time interval and comparing the second predicted set of pressure data to the second pressure telemetry data;solving for a second most likely estimate of the second volume of the pressurant to optimize the second metric; anddetermining, based on the second most likely estimate of the second volume of the pressurant and the second known geometry of the second propellant tank, the most likely second amount of propellant remaining in the second propellant tank. 13. A system as in claim 9, wherein the operations further comprise: determining an amount of inaccessible propellant in the propellant tank, the determining of the amount of inaccessible propellant comprising estimating a location of a spin axis of the satellite based on an estimation of the moment of inertia of the satellite using on-orbit telemetry data, and estimating a distance from the spin axis to a center of a propellant tank. 14. A system as in claim 13, wherein the estimating of the location of the spin axis of the satellite comprises observing a change in the moment of inertia of the satellite in response to a known amount of consumed propellant. 15. A system as in claim 9, wherein the calculating further comprises correlating the pressure telemetry data and temperature telemetry data in at least part of the time interval. 16. A non-transitory computer program product comprising a machine-readable medium storing instructions that, when executed by at least one programmable processor, cause the at least one programmable processor to perform operations comprising: receiving pressure telemetry data and temperature telemetry data for the 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 pressurant;calculating a metric relating the volume of the pressurant, the pressure telemetry data and the temperature telemetry data, the metric calculation comprising reconstructing, based on the received 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, and wherein reconstructing comprises assuming a direct proportionality between the predicted set of pressure data and the temperature telemetry data;solving for a most likely estimate of the volume of the pressurant to optimize the metric; anddetermining, 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. 17. A computer program product as in claim 16, wherein the operations further comprise commanding that the satellite operate a valve isolation system to isolate the propellant tank. 18. A computer program product as in claim 17, wherein the operations further comprise: detecting, over the time interval, that the most likely estimate of the volume of the pressurant is not constant; anddetermining, for the time interval, a drift rate of a pressure transducer associated with a pressure transducer on the satellite that generates at least part of the pressure telemetry data, the drift rate being determined to account for the detected non-constant volume. 19. A computer program product as in claim 17, wherein the operations further comprise: commanding that the satellite de-isolate the propellant tank and isolate the second propellant tank for a second time interval, the second propellant tank having a second known geometry and containing a second amount of propellant and a second volume of the pressurant;receiving second pressure telemetry data and second temperature telemetry data for the second isolated propellant tank;calculating a second metric relating the second volume of the pressurant, the second pressure telemetry data and the second temperature telemetry data, the second metric calculation comprising reconstructing, based on the received second temperature telemetry data, a second predicted set of pressure data for the time interval and comparing the second predicted set of pressure data to the second pressure telemetry data;solving for a second most likely estimate of the second volume of the pressurant to optimize the second metric; anddetermining, based on the second most likely estimate of the second volume of the pressurant and the second known geometry of the second propellant tank, the most likely second amount of propellant remaining in the second propellant tank. 20. A computer program product as in claim 16, wherein the operations further comprise: determining an amount of inaccessible propellant in the propellant tank, the determining of the amount of inaccessible propellant comprising estimating a location of a spin axis of the satellite based on an estimation of the moment of inertia of the satellite using on-orbit telemetry data, and estimating a distance from the spin axis to a center of a propellant tank. 21. A computer program product as in claim 20, wherein the estimating of the location of the spin axis of the satellite comprises observing a change in the moment of inertia of the satellite in response to a known amount of consumed propellant. 22. A computer program product as in claim 16, wherein the calculating further comprises correlating the pressure telemetry data and temperature telemetry data in at least part of the time interval. 23. A non-transitory computer program product comprising a machine-readable medium storing instructions that, when executed by at least one programmable processor, cause the at least one programmable processor to perform operations comprising: measuring, using on-orbit telemetry data at a beginning and an end of a time interval, a moment of inertia of a satellite relative to a spin axis of the satellite, the spin axis being known a priori, the satellite comprising a plurality of propellant tanks, at least one of which provides propellant to supply propellant needs of the satellite over the time interval;assuming that an amount of propellant consumed by the satellite during the time interval is taken equally from each of the at least one of the plurality of propellant tanks providing the propellant; anddetermining the amount of propellant consumed from the at least one propellant tank supplying propellant needs of the satellite over the time interval, the determining being based on a change in the measured moment of inertia of the satellite from the beginning to the end of the time interval. 24. A computer program product as in claim 23, wherein the operations further comprise: calculating a remaining amount of propellant at the end of the time interval in the at least one of the plurality of propellant tanks providing the propellant, the calculating comprising subtracting the amount of propellant consumed during the time interval from an initial amount of propellant in the at least one of the plurality of propellant tanks providing the propellant at the beginning of the time interval. 25. A computer program product as in claim 24, wherein the operations further comprise performing a calculation validity check, the calculation validity check comprising comparing the calculated remaining amount of propellant to a second calculated amount of remaining propellant obtained by another estimation method.
