Debris Avoidance Maneuvers for Spacecraft in a Cluster

Spacecraft formation flying and satellite cluster flight have seen growing interest in the last decade. However, the problem of finding the optimal debris collision avoidance maneuver for a satellite in a cluster has received little attention. This paper develops a method for choosing the timing for conducting minimum-fuel avoidance maneuvers without violating the cluster intersatellite maximal distance limits. The mean semimajor axis difference between the maneuvering satellite and the other satellites is monitored for the assessment of a maneuver possibility. In addition, three techniques for finding optimal maneuvers under the constraints of cluster keeping are developed. The first is an execution of an additional cluster-keeping maneuver at the debris time of closest approach, the second is a global all-cluster maneuver, and the third is a fuel-optimal maneuver, which incorporates the cluster-keeping constraints into the calculation of the evasive maneuver. The methods are demonstrated and compared. The first methodology proves to be the most fuel-efficient. The global maneuver guarantees boundedness of the intersatellite distances as well as fuel and mass balance. However, it is rather fuel-expensive. The last method proves to be useful at certain timings and is a compromise between fuel consumption and the number of maneuvers.