I heard about a form of ion engine that sounds like it has a lot of promise.
http://en.wikipedia.org/wiki/Variable_S ... sma_Rocket
http://www.nasa.gov/vision/space/travel ... lsion.html
A transit to the moon would take longer but be much more efficient in terms of propellant requirements.
On the other hand, distant objects in the solar system would require much less time to reach. This type of engine would significantly reduce the time for a trip to Mars. This is important because while we lack the technology to protect astronauts for long periods outside our magnetic field, reducing the time of exposure is the first step toward a solution.
At any rate, "variable specific impulse magnetoplasma rocket" is fun to say.
