First developed in the 1960s, nuclear thermal propulsion (NTP) rockets had undergone extensive tests. Despite many successful firings, no NTP rockets took flight before the space race ended. But now they are set to make a comeback.
In its pursuit of missions that will take us to Mars and beyond, NASA has been exploring fast and efficient rocket concepts to travel around our solar system. NTP rockets emerged as an ideal candidate.
Unlike hydrogen fuel-combusting chemical rockets, NTP rockets use nuclear fission reactions to heat up liquid hydrogen and turn it into gas (plasma). When the plasma is ejected through a rocket nozzle, the rocket gains thrust.
Compared traditional chemical rockets, NTP rockets provide more powerful propulsion and require a smaller amount of fuel for the same distance. NASA estimated that an NTP rocket can cut the traveling time to Mars from six months to four.
Source: Curious Droid via Youtube