Formation Flight Near Libration Points: Survey and Recommendations

This paper gives a survey of some of the issues involved in formation flight of satellites near a halo orbit. An example of the use of such a formation is to act as a telescope for imaging interesting astronomical objects, such as extra-solar planets. Issues such as formation establishment, stability and dynamics of the formation, control and reconfiguration, coverage analysis, and inter-satellite communications are discussed. Because of the multidisciplinary nature of the tasks involved, an approach that involves several areas of research is needed. I. I NTRODUCTION . Formation flight near libration points offers a unique opportunity to establish a long-baseline imaging capability. Such capabilities are obviously of great long-range importance for NASA. The Challenge Using the experience gained in the last few years with missions such as the Genesis Discovery Mission, we have learned a great deal about the dynamics near the Sun-Earth libration points L 1 and L 2 (see fig. 1). However, this knowledge has also revealed how subtle and sensitive the dynamics are. Formation flight is even more challenging, with its own unique problems of stability, formation reconfiguration, and many other associated issues, which have not yet been addressed. Some of these issues are also being considered in studies of formation flight in nearEarth orbits; cooperative studies will, therefore, be essential. Figure 1. The Sun-Earth and Earth-Moon Lagrange points