Session
Flash Talks Session 3
Location
Salt Palace Convention Center, Salt Lake City, UT
Abstract
Renewed interest in lunar exploration and the development of a sustained cislunar economy has driven demand for low-cost missions supporting mapping, communications networks, navigation services, and scientific studies. Recent growth in rideshare opportunities to the Moon has made small-satellite architectures a viable and cost-effective approach for these missions. Successful execution of these missions, however, depends critically on fuel-efficient and reliable orbital insertion and maintenance strategies, as cislunar missions impose substantially higher delta V requirements than low-Earth orbit missions due to the inherent instability of low lunar orbits. Perturbations arising primarily from lunar mass concentrations drive secular growth in orbital eccentricity that can lead to surface impact within a matter of months. As a result, cislunar spacecraft require periodic orbit maintenance, imposing significant propellant demands on missions already constrained by the large propellant mass required for lunar transfer and orbit insertion.
This work investigates strategies for reducing the propellant cost of maintaining unstable lunar science orbits by exploiting the effects of lunar mass concentrations to mitigate eccentricity growth. A high-precision orbit propagator was developed using modern ephemerides, lunar gravity models, and finite-duration thrust modelling. The propagator was used to characterize the evolution of a representative 50 km circular polar lunar orbit and to identify recurring perturbing events associated with specific lunar mass concentrations.
An optimization framework was then formulated to strategically modify the spacecraft dwell time over regions of positive and negative gravitational anomaly. Candidate thrust manoeuvres were generated around perturbing events and evaluated using an optimization algorithm. This optimization employs a cost function that balances propellant consumption, eccentricity reduction, trajectory preservation, and mission risk. The selected manoeuvres amplify favourable perturbations and damp unfavourable ones to guide the natural evolution of the orbit toward its nominal configuration.
Application of the optimization algorithm to a representative orbit produced a six-thrust maintenance strategy requiring 10.5 m/s of delta V per lunation. This compares favourably with a conventional two burn circularization approach requiring 12.0 m/s of delta V, and represents a 12.5% reduction in propellant consumption. The resulting performance is also consistent with the range of stationkeeping costs reported for the Lunar Reconnaissance Orbiter. The optimized solutions permit temporary increases in eccentricity while allowing subsequent natural perturbations to restore the orbit, indicating that efficient maintenance strategies that intentionally leverage the unstable dynamics of the lunar environment are possible.
These results demonstrate that incorporating knowledge of mascon-driven perturbations into orbit maintenance planning can improve propellant efficiency for cislunar small satellites. The approach offers the potential to extend mission lifetime, reduce propulsion requirements, or reallocate mass toward payload capability in future lunar missions.
Document Type
Event
Optimization of Orbit-Maintenance Strategies for Small Satellites in Cislunar Space
Salt Palace Convention Center, Salt Lake City, UT
Renewed interest in lunar exploration and the development of a sustained cislunar economy has driven demand for low-cost missions supporting mapping, communications networks, navigation services, and scientific studies. Recent growth in rideshare opportunities to the Moon has made small-satellite architectures a viable and cost-effective approach for these missions. Successful execution of these missions, however, depends critically on fuel-efficient and reliable orbital insertion and maintenance strategies, as cislunar missions impose substantially higher delta V requirements than low-Earth orbit missions due to the inherent instability of low lunar orbits. Perturbations arising primarily from lunar mass concentrations drive secular growth in orbital eccentricity that can lead to surface impact within a matter of months. As a result, cislunar spacecraft require periodic orbit maintenance, imposing significant propellant demands on missions already constrained by the large propellant mass required for lunar transfer and orbit insertion.
This work investigates strategies for reducing the propellant cost of maintaining unstable lunar science orbits by exploiting the effects of lunar mass concentrations to mitigate eccentricity growth. A high-precision orbit propagator was developed using modern ephemerides, lunar gravity models, and finite-duration thrust modelling. The propagator was used to characterize the evolution of a representative 50 km circular polar lunar orbit and to identify recurring perturbing events associated with specific lunar mass concentrations.
An optimization framework was then formulated to strategically modify the spacecraft dwell time over regions of positive and negative gravitational anomaly. Candidate thrust manoeuvres were generated around perturbing events and evaluated using an optimization algorithm. This optimization employs a cost function that balances propellant consumption, eccentricity reduction, trajectory preservation, and mission risk. The selected manoeuvres amplify favourable perturbations and damp unfavourable ones to guide the natural evolution of the orbit toward its nominal configuration.
Application of the optimization algorithm to a representative orbit produced a six-thrust maintenance strategy requiring 10.5 m/s of delta V per lunation. This compares favourably with a conventional two burn circularization approach requiring 12.0 m/s of delta V, and represents a 12.5% reduction in propellant consumption. The resulting performance is also consistent with the range of stationkeeping costs reported for the Lunar Reconnaissance Orbiter. The optimized solutions permit temporary increases in eccentricity while allowing subsequent natural perturbations to restore the orbit, indicating that efficient maintenance strategies that intentionally leverage the unstable dynamics of the lunar environment are possible.
These results demonstrate that incorporating knowledge of mascon-driven perturbations into orbit maintenance planning can improve propellant efficiency for cislunar small satellites. The approach offers the potential to extend mission lifetime, reduce propulsion requirements, or reallocate mass toward payload capability in future lunar missions.
