Optimal low-thrust transfers with constraints---generalization of averaging techniques

A unified study of optimal low-thrust transfers is presented, based on the use of averaging techniques. Both minimum-time and fuel-saving strategies using non-constant acceleration are investigated to optimize the trajectory between arbitrary distant orbits. Optimal low-thrust rendezvous could also be treated by the same way. In each case, several constraints are included, either environmental such as Earth oblateness and shadow effect, or technological such as thrust direction limits. The different problems are treated by a generalized averaging method and for each of them, theoretical justification of the approximation is discussed. Results are finally analysed and compared for the low-thrust geostationary transfer mission.