## Abstract

Optimal trajectories are found for the interception of a target in circular, low-Earth orbit, by a vehicle which is initially in a higher orbit. The interceptor vehicle can use both conventional rocket propulsion and, if optimal or necessary, aerodynamic forces to change us orbit. The problem is solved using a direct method, collocation with nonlinear programming, in which the continuous optimal control problem is converted into a discrete problem. Both minimum-time and minimum-fuel trajectories are found. The sensitivity of the optimal trajectories to atmospheric heating-rate constraints is determined. An interesting result is that some minimum-time trajectories enter the atmosphere and use aerodynamic forces for orbit change even when there is sufficient propellant available to accomplish the interception ballistically.

Original language | English (US) |
---|---|

Pages (from-to) | 467-489 |

Number of pages | 23 |

Journal | Advances in the Astronautical Sciences |

Volume | 102 I |

State | Published - Dec 1 1999 |

## ASJC Scopus subject areas

- Aerospace Engineering
- Space and Planetary Science