EXTREMAL CONTROL AND GUIDANCE SOLUTIONS FOR ORBITAL TRANSFER WITH INTERMEDIATE THRUST

摘要

The variational problem of an extremal transfer of a spacecraft between ellipticalorbits via one or more intermediate-thrust arcs with constant specific impulsein a central Newtonian field and spacecraft guidance during the transferare considered. New analytical solutions for the transfers between two coplanarelliptical orbits via one and two intermediate-thrust arcs are obtained. It isshown that an extremal transfer with three thrust arcs would not be as fuel-efficientcompared to the transfers with one and two thrust arcs. Illustrative numericalexamples of extremal transfers using one and two thrust arcs are considered.It is demonstrated that an optimal two-impulsive transfer is economicallyadvantageous compared to the cases of transfers with these thrust arcs,and the Hohmann transfers assuming that the terminal orbits are the circularorbits for the latter case. The proposed analytical solutions are utilized in thederivation of the guidance laws for motion with a thrust arc. These solutionsallow us to compute the guidance commands for any given point of this arcconnecting two terminal points of interest. The guidance laws for an extremaltransfer between two elliptical orbits using only one intermediate-thrust arc arederived.