A method is disclosed for designing an orbit of a spacecraft which allows
the spacecraft to take a small-radius halo orbit near a Lagrange point
while avoiding the prohibited zone where the spacecraft may be shadowed
or might be prevented from making communication. The method makes it
possible to have a closed orbit although being similar to a Lissajous
orbit, under a restricted condition where a propulsion force magnitude
applied to a spacecraft is fixed, and where it rotates at a constant
angular velocity, based on the equation of motion close to a Lagrange
point. The method also provide a theory for guiding/controlling the orbit
of a spacecraft, that is, the embodiment of the above orbit design
method.