Bernd Dachwald
Interplanetary Mission Analysis for Non-Perfectly Reflecting Solar Sailcraft Using Evolutionary Neurocontrol
In: Advances in the Astronautical Sciences, Vol. 116: Astrodynamics 2003 Part II (Proceedings of the AAS/AIAA Astrodynamics Conference 2003, Big Sky (MT), USA) Univelt, San Diego, pp. 1247-1262 (AAS-03-579)


Solar sailcraft trajectories are typically presented for high-performance sailcraft, assuming that the sail is an ideal reflector, or considering the non-ideal reflectivity through an overall efficiency factor. Otherwise, using traditional local trajectory optimization methods, it is difficult to generate the required initial guess. A real solar sail, however, is not a perfect reflector and a thorough trajectory simulation must therefore take into account the optical characteristics of the real sail film that lead not only to a reduced magnitude of the solar radiation pressure force but also to a directional deviation.
Within this paper, minimal transfer times for rendezvous missions within the inner solar system are presented for perfectly and non-perfectly reflecting solar sailcraft, including a typical near-Earth asteroid rendezvous (1996FG3) and a typical main belt asteroid rendezvous (Vesta). For the different solar radiation pressure force models, the minimal transfer times are compared, extending thereby the currently available data to moderate-performance sailcraft of the first generation.
Using evolutionary neurocontrol as a global trajectory optimization method, it is shown that there is a considerable increase of about 5-15% in the minimal transfer times, if the non-perfect reflectivity of the solar sail is taken into account. This fact must be considered for a thorough mission analysis. The simplification that the non-ideal reflectivity of the sail can be modelled with an overall sail efficiency factor should only be made for very preliminary mission analyses.