UC Irvine

The use of CubeSats as space observation missions is now a reality. CubeSats are satellites in the category of small satellites (around 10 cm x 10 cm x 10 cm) that started as simply educational projects for students. But they soon spread out to scientific investigation and exploration.

In this work, a low-energy transfer is designed and studied to transport these small satellites from low Earth orbit to orbit about the Moon. The theory behind low-energy transfers, as well as the computational methods, are described. A low-energy transfer is a transfer that exploits natural pathways in position-velocity space created by the forces of the Sun, Earth, and Moon acting on the CubeSat to reach the final target. The three-body problem in a rotating frame shows equilibrium points. Periodic orbits exist in the neighborhood of these equilibrium points. The low-energy transfer takes advantage of these periodic orbits and their stability properties using them as staging orbits. With precise maneuvers, a vehicle can be placed on a stable manifold of target periodic orbit such that it naturally travels to the target periodic orbits with little use of propellant. The transfers reduce the CubeSat propulsion requirements at the expense of transfer time. These transfers normally take 4 to 6 months to travel from a low orbit at the Earth to an orbit about the Moon.

Following the procedures to design the transfer, this work develops, analyzes and compares a low-energy transfer with other transfer options. A case study is also shown to discuss the values obtained. The low-energy transfer is shown to reduce the propulsion requirements significantly in comparison to conventional direct transfers.