A Conjoint Analysis of Propellant Budget and Maneuver Life for a Communication Satellite

Maneuvers require velocity augmentation to control a satellite at the defined orbit. The velocity augmentation provides achieving geostationary orbit, compensating orbital perturbation, orbit dispersion correction, and any other maneuver's operations for a communication satellite. All maneuvers and propellant consumption must be taken into account in the propellant budget for successful mission management. In this study, a straightforward method was proposed to calculate satellite maneuver life or associated propellant budget for general purposes. The method provides enough accuracy for general mission planning. However, communication satellite accurate end of life estimation, especially in the last three months is vitally important and depends on many factors. According to the performance requirement of procurement's standard, the propellant budget and associated satellite maneuver's life are calculated based on the worst-case or adverse three-sigma. The worst-case calculations include allocations for inefficiencies, velocity uncertainties, dispersions resulting from thruster firings, propellant residuals, the selected thrusting, and maneuver strategies' performance. High accuracy remaining propellant estimation is necessary for a successful end of life operation and decommissioning. The cost of early deorbit because of propellant misestimation is millions of dollars. Accurate remaining propellant and associated maneuver life analysis can be performed in different methods.The most common three methods are pressure, volume, temperature (PVT), bookkeeping (BK), and thermal propellant gauging (TPG). The propellant accuracy analysis shows that the propagation of uncertainties is related to system design, tank fill ratio, propellant load accuracy, orbital maneuver's inefficiency, pressure and temperature sensors, transducers, telemetry resolution, and error in equipment test data. Comparing the methods, PVT provides accuracy between ±27.81 kg to ±38.93 kg, depending on equipment size and accuracy. BK currently provides the best estimation and the highest gauging accuracy between ±9.83 kg to ±13.76 kg. TPG provides accuracy between ±10.52 to ±14.73 kg for some cases. However, the satellite operators request ±1 kg estimation of the remaining propellant to extend the lifetime and reduce costs. The satellite manufacturers should optimize propulsiıon and attitude control subsystem design and manufacturing, including propellant management device performance, applied sensors reliability and accuracy, and tank expansion performance over a mission life.