Why can’t we build nuclear powered rockets in order to reach the moon or mars and the beyond?
We have nuclear powered subs, aircraft carriers etc.
I read the US tried in the early years of the Cold War but cancelled the program.
What gives?
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Okay so the other answers answered about nuclear power supplying electricity to ships. Which does happen in some situations, though it’s a cost benefit of “how badly do we need this nuclear power vs the chance of the rocket raining nuclear material down if it fails.”
The other thing about the Cold War nuclear rockets is that they were absolutely terrible for life in every iteration.
Rockets use gas to propel them. Using electricity from nuclear power isn’t directly convertible in an easy way in space like it could be in atmosphere. You can use electricity to spin a turbine for propulsion in atmosphere(or fluid, like water) but not in vacuum.
Though reactor shielding is heavy. Literally lead. Which doesn’t work well for weight on an aircraft while keeping the crew from turning to goop or shielding it if it crashed.
You could use other forms of power though. Like the thermal energy.
Which was a concept. A gas goes into the reactor, gets heated up by the reactor, and is expelled out faster on the other side. Project Pluto tended to also irradiate the air that was heated. So all the throughput of the engine, was turned into radioactive air. Which is bad. That was scrapped because a nuclear fallout air freshener was an issue.
In space you could use the thermal power to expand a gas and push like a rocket but that’s expensive, heavy, and also has the same issues as launching any other radioactive material. They absolutely could not be used in atmosphere because they would literally be dumping radiation as exhaust. They are more efficient though. So possibly are being looked at for Mars.
There’s the project Orion, which used nuclear bombs to push a ship forward. Literally detonate the bomb behind a shield and use it to push the ship. This was more theory than practice since it needed to withstand a nuclear detonation and the shockwave. This one seems self explanatory why there are issues.
Edit: there are electric drives but they produce low thrust to weight but can be very very efficient. So longer burn times. Deep space probes like people mentioned but not great for manned “get there before life support runs out” missions.
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