Fuel-Optimal Low-Earth-Orbit Maintenance.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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First-order solutions indicate that a forced Keplerian trajectory FKT obtained by thrust-drag cancellation is as fuel-efficient as a Hohmann transfer. Further analysis has shown that the FKT is not Mayer-optimal. Therefore there must exist another trajectory that matches or exceeds the efficiency of the Hohmann transfer. The application of this result to the fuel-optimal orbit maintenance problem implies that periodic reboosts must be more efficient than an WT profile. This research begins with the formulation of an optimal periodic control OPC problem to determine the minimum fuel-reboost strategy. The problem is numerically solved by a spectral collocation method. The optimization code is further modified to increase accuracy and reduce sensitivity to initial guesses. The results of this effort identified a trajectory for a sample satellite that was 3.5 more efficient than an ideal impulsive Hohmann transfer over the same period of time. From the optimal code, a maximum thruster size is also identifiable for a set of initial conditions. The optimal trajectory can save as much as 10 of the propellant budget when compared to finite-bum Hohmann transfers.
- Celestial Mechanics