Formation Flying for Reconfigurable Space Structures

[2019- ongoing]

Spacecraft (or satellite) formation flying is a concept of coordination among a group of spacecraft in order to accomplish a common goal. According to NASA Goddard Space Flight Center, it may be defined as “the tracking or maintenance of a desired relative separation, orientation or position between or among spacecraft.”

The goal of this project is to identify a fuel-optimum trajectory for the reorganization of a spacecraft formation from one configuration to another. The ability to reconfigure a formation provides an extra dimension of flexibility to the mission. As fuel is the most important resource in space, optimization of fuel during the reconfiguration maneuver is essential to the longevity of the mission.

The dynamics of each agent of the formation can be approximated by the Clohessy-Wiltshire equations, which are the linearized form of the relative equations of motion near a reference point in circular orbit. Each agent must go from their initial position to a designated final position while minimizing the total fuel consumption and also avoiding collision with other agents in the formation.

The following figure shows, as an example, the reconfiguration from a collinear (in the LVLH frame) parking orbit to a two-dimensional elliptic deployed orbit, where all agents are orbiting a virtual reference point. Both the initial and final configurations are in the form of solutions to the Clohessy-Wiltshire equations, which makes them stable without the need for station-keeping.