Fart power. Not bad. Methane burns pretty clean and there's allot of it laying (or floating) around, and apparently it could be manufactured on both the moon and on mars. I also understand that it has some performance advantages over what is being used today. But I remember reading something about NASA dropping Methane/Liquid Oxygen for use in the "Vision for Space Exploration" initiative, which would suposedly get us back to the moon some day in the distant future, in favor of the technology we were using 40 years ago, for reasons that were not completely clear to me (therefor probably politically or financially based).
Maybe someone connected to the space program can explain why less expensive, more efficient and easier to handle fuels have been benched in favor of the tried and true expensive, inefficient and caustic stuff?
I think the future of space propulsion will probably include allot of different kinds of systems, including liquid and solid fuels, depending on what it is they need to do; power launch systems, long term acceleration, maneuvering, station keeping etc.
I've read a little about some of the systems currently in development, and Wikipedia has a nice entry that highlights most of them at http://en.wikipedia.org/wiki/Spacecraft_propulsion
. The much cooler, more theoretical stuff can be found at http://en.wikipedia.org/wiki/Breakthrou ... cs_Program
I suppose the Holy grail would be some kind of gravity manipulation system, which would assume we acquire some kind of understanding of what gravity actually is at some point. Maybe some of what we learn from the Large Hadron collider, once they get it on line, will get us a little closer.
Not sure how we are going to get there if we continue investing in crap we can already do, badly. Seems to be the general pattern of government spending, though.