This article gives the casual reader the distorted view that one could travel the solar system at will by using these methods. These are generally small perturbations on the much larger primary propulsion requirement that is fixed by standard two-body orbital mechanics.

John Oldson
San Diego, Calif.

In the course of its eccentric orbit, the moon moves through the mean positions of the Earth-moon L1 position. Maintaining a space station at L1 would be a dubious proposition.

David R. Burwasser
Oberlin, Ohio