SIMULATION OF FORMATION FLIGHT NEAR LAGRANGE POINTS FOR THE TPF MISSION

摘要

The TPF Mission (Terrestrial Planet Finder) is one of the center pieces of the NASA Origins Program. The goal of TPF is to identify terrestrial planets around stars nearby the Solar System. For this purpose, a space-based infrared interferometer with a baseline of approximately 100 m is required. To achieve such a large baseline, a distributed system of five spacecraft flying in formation is an efficient approach. Since the TPF instruments needs a cold and stable environment, near Earth orbits are unsuitable. Two potential orbits have been identified: a SIRTF-like heliocentric orbit and a libration orbit near the L_2.Lagrange point. In this paper, we focus on the mission in an orbit near L_2. Our work showed that for the TPF Mission: 1. Formation flight near L_2 is dynamically possible. 2. Linear control around a nonlinear baseline libration orbit near L_2 is adequate. The use of dynamical systems theory not only provides a global view of the phase space showing all the possibilities for the nominal trajectories, but also provides additional structures such as invariant manifolds, that simplify many aspects of the mission analysis such as the transfer from Earth to libration orbit.