http://news.yahoo.com/nowhere-japans-growing-plutonium-stockpile-064038796.html

A half century after being developed, nuclear pulse propulsion remains the only practical system of interplanetary travel. What is required to launch a bomb propelled mission to the outer solar system? Well, first you need.…..bombs.

There is no shortage of bomb material on planet Earth. The problem is lack of a vehicle that can get this material to the nearest place a nuclear mission can be launched; the Moon. For over a quarter of a century a launch vehicle capable of sending significant payloads (and people) to the Moon has been lacking. The Space Transportation System, aka the space shuttle, was a dead end as far as exploration due to the lack of funding for a Sidemount cargo version.

Now we wait on the SLS.

http://www.sciencedaily.com/releases/2012/12/121228100748.htm

Only this human rated Heavy Lift Vehicle (HLV) with a powerful escape tower will be suitable for transporting survivable packaged fissionables to the Moon. It is not only the fissionables that are required; hundreds of tons of water from lunar ice deposits are necessary to fill the radiation shield for any such Human Space Flight Beyond Earth Lunar Orbit (HSF-BELO).

Eventually lunar resources can be used to actually construct atomic spaceships and also the thorium reactors necessary to power colonies in the outer system. It is the establishment of a beam propulsion infrastructure that will finally open up the solar system to large scale development. This will require a massive infrastructure on the Moon. Such a base will serve as insurance against an extinction level event wiping out our species. As such it deserves a full measure of DOD funding. Like that trillion dollars that is going to be spent on the F-35 stealth fighter over the next half century.

Only monthly Heavy Lift Vehicle launches of payloads to the Moon can be considered as a beginning to a true space program- where Apollo left off. There is no cheap and there is no flexible path.