Transfers around Phobos via bifurcated retrograde orbits: Applications to Martian Moons eXploration mission

Quasi-satellite or distant retrograde orbits are stable orbits in the restricted three-body problem will be used in remote planetary satellite missions like JAXA's Martian Moons eXploration (MMX). Due to Phobos' irregular gravity field, the proximity operations of the MMX mission require sophisticated techniques for transfers and maintenance between different quasi-satellite orbits. This paper focuses on the design of transfer trajectories between Quasi-Satellite Orbits (QSO) around Phobos. We utilize horizontal bifurcated Multi-Revolution Periodic QSOs (MP-QSOs) that are found in the vicinity of an ellipsoidal Phobos under the assumptions of the circular Hill Problem. Transfer strategy via MP-QSOs is explored through transfer maps that illustrate transfer design space between different altitudes QSOs. It is found that transfers via MP-QSOs provide insights on minimum..V transfers and the parameters determining the transfer cost. The proposed transfer method is explicitly applied to MMX baseline QSOs. This research has identified that transfers between high(100 x 200 km)-to-mid(50 x 100 km), mid-to-low(30 x 50 km), and lower altitude(< 30 km) QSOs via MP-QSOs can be achieved with as low as 11.63 m/s, 3.99 m/s, 1.74 m/s, and 0.97 m/s, respectively.