Key Features of a Nuclear Rocket

My previous article was about a nuclear engine design to be used on the very last stage of a rocket. It would provide low thrust for years. A true nuclear rocket with all stages nuclear should have some distinct features separating it from the rest.

The major difference would be the flight trajectory compared to trajectories with gravity turn. Gravity turn consumes less fuel compared to a vertical approach. The reason I am insisting on this less efficient path is because of safety. The probability of a rocket failing and exploding on the sky is not zero. A rocket with a nuclear reactor orbiting the earth and dropping its used-up radioactive stages on several location on earth is not a feasible option. In case of a vertical trajectory, used-up stages would return close to the launch site. Allowing better handling of nuclear waste.

Russia’s Luna spacecrafts were sent to the Moon without intermediate LEO. In an article it states that the inefficiency of the trajectory can be reduced, if the rocket has high thrust to weight ratio (TWR). The current rockets have TWR close to one. High TWR would require more engines and faster consumption of the mono propellant. They may even require more stages to maintain high TWR. As the propellant is consumed, TWR increases. There is a limit to that, else too much acceleration would shatter the rocket and its payload.

The vertical path is applicable until the rocket reaches the escape velocity of the Earth. Beyond that the rocket can follow any path. This guarantees no stages of the rocket would fall outside the launch peripheral.

A nuclear rocket would generate thrust by pressurizing the mono propellant by heat. This is a huge saving from the heavy weight of a fuel tank. Unlike a combustion engine. The heat generation of a nuclear reactor continuous even after all the propellant is consumed. As a result, the consumed stages of the rocket can generate thrust while they are falling on Earth. This allows all stages prior to the escape velocity to be recovered and even reused. I will detail it on my next article.