http://launchloop.com/LunarFlyby
http://svs.gsfc.nasa.gov/vis/a000000/a003300/a003364/
https://space.stackexchange.com/questions/2103/how-to-calculate-delta-v-for-lunar-flyby
https://space.stackexchange.com/questions/4027/has-luna-been-used-for-gravity-assist-for-interplanetary-probes
