After fantasizing about the idea in the 1950s, NASA has turned its eyes back to nuclear-powered spacecraft. The agency has just launched the initial phase of a new program for nuclear propulsion while Russians and Chinese continue theirs at full speed.
“NASA is leading an effort, working with the Department of Energy (DOE) to advance nuclear technology in space,” it says in its announcement published yesterday. “The government team has selected three reactor design concepts for a nuclear thermal propulsion system.”
According to NASA, this reactor is the critical component for a nuclear thermal engine that uses uranium as fuel.
The dream of nuclear engines in space
The idea of using controlled explosions to power rockets is not new. In fact, dates from the end of the 19th century, when it was originally proposed by Russian explosion expert Nikolai Kibalchich and German engineer Hermann Ganswindt.
In the mid-1940s, the Americans made calculations that confirmed that nuclear explosions can be used to power a ship. In fact, it was discovered that such a ship would be much more efficient and faster than one driven by chemical reactions or ion engines.
In the 1950s, the United States Government tried to make the idea of an atomic ship a reality with the Orion Project (which has nothing to do with the Orion spacecraft that will soon take humans to the Moon). The Orion nuclear ship would have used nuclear pulse propulsion, ejecting a small nuclear bomb by the stern of the ship to explode and use the momentum of its shock wave.
The American space agency abandoned the project for fear of the possible fall of radioactive material on Earth and the prohibition not to detonate nuclear bombs in space imposed by the non-proliferation treaty. And, in addition, NASA faced the challenge of get to the moon before the Soviet Union.
The new nuclear propulsion in space
NASA’s idea is not to go back to Project Orion, but to create a nuclear propulsion system that uses a fission reactor to heat a liquid and power a spacecraft with higher efficiency and power than a conventional rocket or ion engine.
The Russians and Chinese are also working on boost systems that use nuclear reactors as an energy source. But, in their case, they are developing electrical systems to power ion engines. The Chinese believe they will be able to develop a nuclear-powered ion engine that will take them to Mars in just 39 days.
The Russians say their Zeus spacecraft – developed by the space agency’s arms arm Roscomos – will also use a fission reactor to power an ion engine that will allow them to maneuver in Earth orbit to hunt down enemy ships in case of war.
NASA’s idea is different: they want to use thermal nuclear propulsion. The system does not generate electricity to power an ion engine. Instead, it generates heat that is transferred to a liquid that turns into a gas. The gas comes out under pressure from the rear nozzles of the house and generates an impulse that moves the ship forward.
Compared with the Russian and Chinese projects, the idea of a steamship seems quite pedestrian. But NASA says it is the most efficient and feasible way to travel at high speed right now. In fact, they seem convinced that it is the best way to get crews and cargo to Mars on a continuous basis. Ion engines still don’t have the power to move a spaceship at high speed. That is why they are mostly used to maneuver satellites or the new Chinese space station.
The North American agency has already chosen three private companies for the first phase of development of its thermal nuclear engine, which comes after several initial experiments and analyzes. Over the next 12 months, the three companies will compete to create the first design, culminating in an evaluation to choose the path to the final design that will render Elon Musk’s Starship ships obsolete in a few years.