When dealing with mission requirements calling for highly stable gravitational and thermal environments, one of the common options always considered is that of the heliocentric Earth trailing orbits (HETO). This is the case, for instance, of the Laser Interferometer Space Antenna (LISA), a joint ESA-NASA effort aimed at detecting gravitational radiation from deep-space sources, hence testing the fundamental gravitational theories. This article is about the low-thrust transfer trajectory optimisation for a three-satellites flotilla to a HETO. To this end, and after a brief presentation of the selected reference mission (LISA), a five impulses transfer strategy is conceived to build a solution guess for the ignition of the Sequential Gradient Restoration Algorithm (SGRA), which solves the full optimal control problem (FOCP) of finding the optimal low thrust profiles injecting each SC to its respective target orbit while minimising a given functional. An inequality path constraint on the Solar Aspect Angle (SAA) is imposed on the low-thrust vector of each SC. Finally several relevant conclusions are derived from the presented results, among them the direct relationship between the departure velocity from Earth, the final SC masses and the transfer duration. (C) 2004 Elsevier Ltd. All rights reserved.
