| In the past several years a few authors have looked into the properties of a lunar ballistic capture trajectory that originates at a point near the Earth and arrives at the Moon approximately 90 to a few hundred days later. With the correct ΔV at Earth the spacecraft arrives at the Moon with an energy less than zero with respect to the Moon. The spacecraft is effectively captured by the Moon, without the need for a second ΔV. In order to achieve this, the spacecraft first travels to near the Earth-Sun sphere of influence where the Sun perturbs the orbit allowing it to approach the Moon in such a way that it arrives at the Moon with negative energy. This trajectory allows a spacecraft to be put into orbit about the Moon with less total ΔV than is needed using a Hohmann transfer. This study examines the properties of one specific family of these transfers. The properties analyzed provide insight into initial conditions at Earth and models are developed to describe these conditions. The results allow mission design for these transfers to be performed entirely with a forward time propagation scheme, something that has not been accomplished previously. |
