  Low-energy transfers are advantageous for lunar exploration missions due to
low fuel consumption and extended launch periods. This paper is devoted to the
classification of interior transit orbits and their application on low-energy
transfer in the Sun-Earth/Moon planar bicircular restricted four-body problem
(PBCR4BP). First, the Lagrangian coherent structures (LCSs) are introduced to
generate the interior transit orbits. The number of periapses about the Moon is
selected as the classification parameter and mapped into the LCSs, achieving
clear classification boundaries. Then, the evolution laws of the
classifications with respect to energy and solar gravity perturbation are
discussed and summarized. Construction strategies for low-energy transfer are
proposed based on the classifications and their evolution laws. Numerical
simulation of the transfer trajectories verifies the effectiveness of the
proposed strategies. The dynamical behaviors and transfer characteristics of
transit orbits and their families are revealed, and a direct link between
transit orbit families and low-energy transfers is finally established.
