> The big problem with nuclear propulsion is always: What happens if a rocket with such an engine explodes at the start? The big problem is that most people do

> The big problem with nuclear propulsion is always: What happens if a rocket with such an engine explodes at the start? The big problem is that most people don't realize that isn't a problem at all. We've been launching radiation-powered devices into space for decades in the form of RPS's, Radioisotope-powered systems. In one launch, the rocket exploded and even then the radioactive parts were unharmed[0] And 'accidentally reenters the atmosphere' isn't really a thing. Once an object is in orbit above a certain height, it takes a lot of energy to get it out of orbit. The only alternative is waiting for the very faint amount of atmosphere to drag on it and bring it down- and anything about 1000km, that would be decades of waiting. We launch the radioactive components safely, as we have lots of experience doing. We then assemble the nuclear engine in-orbit at an orbit above 1000km. Then we go to Mars! [0]https://rps.nasa.gov/about-rps/safety-and-reliability/ https://rps.nasa.gov/about-rps/safety-and-reliability/