Henry probably knows about this already, but it was news to me: http://www.stk.com/pdf/white_papers/0800_wsb.pdf
There is a class of trajectories from LEO to lunar orbit for which the lunar orbit insertion is entirely ballistic (no delta-V required). This reduces the total delta-V for a one-way LEO-to-moon mission by about 25%, relative to the classic Apollo-type trajectory. What you do is launch on a long ellipse toward the Sun, way out past the Moon's orbit around the Earth. You're still in Earth orbit, but the perturbations on that orbit due to the Sun and Moon are significant. If you do it right, the perturbations warp the orbit to a much lower eccentricity, such that the return trip passes lunar orbit at a speed similar to the Moon's. Then a close approach past the Moon bends the velocity vector around parallel to the Moon's velocity, or at least close enough to put you into a (highly elliptical) lunar orbit. Finding these trajectories is the sort of problem which cannot be solved analytically. It requires very detailed numerical simulation, coupled with a lot of orbital insight to guide the process. Nevertheless, it's been done, and it's getting easier to do. The Japanese lunar probe Hiten used such a trajectory a few years ago. Cheers! --Stu _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
