orbital cycler

The orbital cycler is an economical method for travel within the Solar System proposed by Buzz Aldrin. It turns out that there are stable orbits that cross the orbits of both Earth and Mars. Aldrin has suggested placing a large permanent station in such an orbit. Travelers would embark on the station when it passed Earth, and disembark as it passed Mars. The energy cost for the traveler is simply the cost to make the rendezvous at each end.