2. Nuclear thermal rocket concept

NASA Reignites Program for Nuclear Thermal Rockets

Figure 1 from The Nuclear Thermal Propulsion Stage (NTPS): A Key Space Asset for Human Exploration and Commercial Missions to the Moon

Realistic Designs A-G - Atomic Rockets

Project Rover: The original nuclear-powered rocket program -- ANS / Nuclear Newswire

NASA's 'Nuclear Option' May Be Crucial for Getting Humans to Mars

PDF] Overview of High-Performance Centrifugal Nuclear Thermal Rocket Propulsion System

Why NASA wants to test a nuclear rocket engine for a Mars mission

Nuclear pulse propulsion - Wikipedia

Nuclear propulsion may be key for humanity getting to Mars, News

Space Nuclear Propulsion - NASA

2 Nuclear Thermal Propulsion, Space Nuclear Propulsion for Human Mars Exploration