TITLE:
Transfers from the Earth to L2 Halo orbits in the Earth-Moon
Bicircular Problem

AUTHORS:
Jose J. Rosales^(1), Angel Jorba^(1) and Marc Jorba-Cusco^(2)
(1) Departament de Matematiques i Informatica
    Universitat de Barcelona, Gran Via 585, 08007 Barcelona, Spain
(2) Universidad Internacional de la Rioja (UNIR),
    Av. de la Paz, 137, 26006 Logro\~{n}o, Spain

E-mails: rosales@maia.ub.es, angel@maia.ub.es, marc.jorba@unir.net

ABSTRACT:
This paper deals with direct transfers from the Earth to Halo orbits
related to the translunar point. The gravitational influence of the 
Sun as a fourth body is taken under consideration by means of the 
Bicircular Problem (BCP), which is a periodic time dependent
perturbation of the Restricted Three Body Problem (RTBP) that includes
the direct effect of the Sun on the spacecraft. In this model, the 
Halo family is quasi-periodic. Here we show how the effect of the Sun 
bends the stable manifolds of the quasi-periodic Halo orbits in a way 
that it allows for direct transfers.