NASA’s push for a new nuclear rocket engine is not just another upgrade to the hardware we strap to the bottom of spacecraft.

Modern spaceflight rests on a deceptively simple idea: a machine that carries its own fuel and oxidizer, then hurls exhaust backward fast enough to push itself forward. The person who first turned ...

However, there are two major problems with nuclear rockets. First, the heat generated has to be carefully controlled if you don't want the engine to end up simply melting. The other is how to control ...