Nukes in Space

Most Kerbal Spaceship Ever
This video reminded me of my post on the subject and prompted me to do a little digging. The biggest problem mentioned, neglecting the whole getting a zillion tons of steel into orbit thing, is getting rid of excess heat. I'm pretty sure all spacecraft have that problem and I'm likewise sure that NASA has a solution. Getting rid of the waste heat from a large nuclear power plant would require an extra large heat sink*, but a nuclear submarine is a large object, with acres** of outside surface area where heat sinks could be mounted. It might not be hydrodynamic any more, but that wouldn't be a problem, would it?

Anyway, I'm poking around and I came across this synopsis of the early years of nuclear propulsion. It still astounds me that the US Government committed billions of dollars to the construction of a uranium enrichment facility before they knew whether they could make an atomic bomb that would work. And then they start on new projects:

Rethinking Submarines as Spaceships
Part One
Once the A-bomb was developed physicists turned to harnessing the new mode of power in other ways. The US Air Force decided that it wanted an atomic powered bomber that could reach anywhere in the world non-stop without refueling. It dreamed of giant planes that could stay in the air on indefinite patrol, possibly only coming down every few weeks for crew rotation. Obviously an impossible dream, but they set to work toward that goal. Two B-36 bombers were dedicated to be modified to carry experimental reactors.
As the saying goes, the air force went off half-cocked in their efforts. As an experimental unit, the reactor was hung under the belly of the B-36. It provided no power for propelling the plane. It was for demo purposes and perhaps a PR show more than anything. The Air Force gave up the effort after two flights of that contraption. They concluded that the required shielding for the reactor made the concept impractical. Probably more important to the dismissal was that they never got seriously involved in a design for a nuclear-powered type of jet engine for such an aircraft.
The jealous rival of the Air Force, the Navy, picked up the idea in 1947 of using nuclear energy to propel machinery and asked industry to provide a design for a submarine reactor. Nukes were perfect for their submarines. It would be able to stay on patrol indefinitely without refueling or surfacing. And so the transition started as the submarines and bigger naval ships were designed for the new mode.
The design for the world’s first operational atomic powered ship, a submarine, was accepted and the keel laid in 1952. lt was named the USS Nautilus. It was launched in 1954 and commissioned later that year. 

Nine years after the end of the war the US Navy launched their first nuclear powered submarine. They designed and built a nuclear power plant, installed it in a submarine, launched the submarine, and it worked. That is phenomenal.

The first nuclear power plant came alive in 1951.

*   the whole heat in space is a real problem. I haven't found a good explanation of how it is handled.
** Okay, it's only about 1.5 acres.