NERVA

• https://en.wikipedia.org/wiki/NERVA
• https://en.wikipedia.org/wiki/Pulsed_nuclear_thermal_rocket

Development news:

• https://www.nasa.gov/press-release/nasa-darpa-will-test-nuclear-engine-for-future-mars-missions
• https://www.nasa.gov/mission_pages/tdm/nuclear-thermal-propulsion/index.html
• Testing by 2027
• This seems to be for a new engine?