First I've heard of it, but then again I'm not a rocket scientist... Interesting though. However it sounds like it would require a lot of energy for the accelerating and deceleration phases, even with gravity assist, and energy means fuel. Not to say it can't be done, but it might not be the small vehicles imagined in the proposal.Also, this is very similar to the Mars cycler, just smaller and with two vehicles to allow a brief stay and short overall mission time.