The idea of nuclear rockets has quite a bit of merit. Many of the original creators of the atom bomb went on to participate in "Project Orion", an Air Force endeavor to harness nuclear energy for propulsion. "Orion" ran into snags due to nonproliferation treaties and eventually got scrapped in the late 1960's, but progress has slowly been made on rockets that use nuclear reactions both directly and indirectly for acceleration. Very cool stuff.
There's something intrinsically satisfying about shoving a nuke under a Big metal plate.
I guarantee, that sucker will GO!
Isn't that what used to be called "Ion Drive"?
I noticed some comments about ion propulsion; Japan has the Hayabusa mission which is currently using Japan's microwave ion propulsion system on its way to recover samples from the asteroid Itokawa in the asteroid belt. If it manages to carry this mission off, it is supposed to be back to Earth with samples in 2007 -- a pretty quick trip considering how long it has taken to go to Mars or the lastest mission to Mercury's schedule.
Coherent nuclear resonant spin allows a substance (made of boron and oxygen) to capture radiation (x-ray and possibly gamma) when in a magnetic field. When the field is reversed the radiation then continues to propagate. Use it to power a plasma rocket and we are on our way.