Mission design for the MMS tetrahedron formation

The trajectory design strategy for the magnetospheric multiscale mission (MMS) involves obtaining a reference path that traverses certain regions of the Earth's magnetosphere. Relative to this defined reference path, a tetrahedron formation is established at certain points during the mission. Initially, the spacecraft will fly in a tetrahedron formation through different regions of the magnetosphere close to the magnetic equatorial plane. However, to explore regions that are almost perpendicular to the ecliptic plane, a dramatic plane change is needed. To minimize fuel and to explore the magnetosphere's deep tail region, a double lunar swingby is used. A preliminary automated procedure has been developed to design the reference path. Once the reference path is generated, an optimization scheme is utilized to implement the maneuver sequence that results in adequate formation flying for the magnetospheric explorations.