This book studies several problems related to the analysis of planned or possible spacecraft missions. It is divided into four chapters. The first chapter is devoted to the computation of quasiperiodic solutions for the motion of a spacecraft near the equilateral points of the EarthOCoMoon system. The second chapter gives a complete description of the orbits near the collinear point, L 1, between the Earth and the Sun in the restricted three-body problem (RTBP) model. In the third chapter, methods are developed to compute the nominal orbit and to design and test the control strategy for the quasiperiodic halo orbits. In the last chapter, the transfer from the Earth to a halo orbit is studied. Contents: Quasi-periodic Solutions Near the Equilateral Points of the Earth-Moon System; Global Description of the Orbits Near the L 1 Point of the EarthOCoSun System in the RTBP; Quasi-periodic Halo Orbits; Transfer from the Earth to a Halo Orbit; Appendices: The JPL Model; Reference Systems and Equations of Motion; The Model Equations Near the Equilateral Points in the EarthOCoMoon System; Transfer Between Halo Orbits of the RTBP. Readership: Applied mathematicians, computational physicists and aerospace engineers.