Accession Number:

AD0687648

Title:

LOW THRUST SWINGBY TRAJECTORIES,

Descriptive Note:

Corporate Author:

LOCKHEED MISSILES AND SPACE CO PALO ALTO CALIF LOCKHEED RESEARCH LAB

Personal Author(s):

Report Date:

1968-01-01

Pagination or Media Count:

16.0

Abstract:

The paper considers the problem of optimum low thrust power limited interplanetary transfers which involve the swingby of an intermediate planet. The necessary conditions for an optimum low thrust swingby are examined under the assumption that the trajectory receives an impulsive velocity change at the swingby planet. When the distance of closest approach is not constrained, the optimizing conditions require that the vector adjoint variable corresponding to velocity is parallel to the relative velocity vector and rotates through the same swingby angle as the relative velocity vector. When the distance of closest approach is constrained, the adjoint is no longer parallel and there is an additional discontinuity in the adjoint variables. The condition for the optimum swingby time is that a modified Hamiltonian is continuous. It is shown that as long as the hyperbolic excess velocity at the swingby planet is large enough, the impulsive velocity approximation should be sufficient and the other perturbation effects of the planet should be small. A computation method is outlined and a hypothetical swingby presented. Author

Subject Categories:

  • Spacecraft Trajectories and Reentry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE