Deployment of a two-spacecraft formation into a highly elliptic orbit with collision avoidance

The finite-thrust deployment of a two-satellite formation into a highly elliptic orbit is optimized by means of an indirect approach, which is based on the theory of optimal control. Earth oblateness and gravitational perturbations from Moon and Sun are considered. The optimization procedure provides the engine switching times and the thrust direction during each burn in order to transfer the satellites to the same prescribed final orbit with assigned distance between them at the apogee passage; the total final mass is maximized. A minimum-distance constraint is introduced when required to avoid collision risk. Different deployment strategies are analyzed; in particular, the classical chaser-target approach is compared to cooperative deployment. Necessary conditions for optimality are derived and numerical results presented. © 2012 by the Authors.