In the race to get the first humans to Mars, NASA is betting big on nuclear rocket engines to get its astronauts to the red planet.
Earlier this year, the agency announced a partnership with the Defense Advanced Research Projects Agency, or DARPA, to develop a rocket that uses nuclear propulsion to transport crews of astronauts to deep-space destinations like Mars. This type of technology would significantly reduce the time needed to reach Mars, making long-duration spaceflight less risky for the humans on board.
A conventional spacecraft powered by burning liquid fuel typically takes seven to eight months to reach the red planet. Scientists have said that nuclear rocket engines could cut at least a third of that time.
NASA Administrator Bill Nelson said the shorter trip would give crews more flexibility on Mars missions.
“You allow yourself to be on the surface for about three or four weeks and come back in a reasonable amount of time, rather than having to be away for two or three years,” he said.
A shorter round trip also means astronauts would be exposed to less cosmic radiation while in space. Studies have shown that without the protection of Earth’s atmosphere and magnetic field, humans can receive a full year’s worth of radiation on Earth in just one day in space. For missions to Mars, that means an astronaut could be exposed to radiation levels 700 times higher than on Earth. according to the European Space Agency.
To reduce these risks, DARPA, the branch of the Department of Defense responsible for experimenting with new and emerging technologies, is developing a rocket powered by nuclear thermal propulsion. The program has been dubbed DRACO, short for Demonstration Rocket for Agile Cislunar Operations.
The system uses the high heat of a fission reactor to convert liquid propellant into gas, which is then piped through a nozzle to propel the spacecraft.
This type of propulsion can generate more thrust and is at least three times more efficient than chemical rockets. according to nasa. That means having to carry less fuel on board, which frees up space to transport more equipment, science experiments or other cargo to the Martian surface.
«It can completely change the way people think about what’s possible in space: what you can take, how fast you can get there,» said DARPA Director Stefanie Tompkins. “You have much more flexibility to get where you want, when you want.”
And while the system runs on nuclear power, Nelson said it would use low-enriched uranium instead of weapons-grade, highly enriched uranium.
“This is safe nuclear technology,” he said.
He added that tests of the nuclear rocket motor would not occur on Earth and would instead take place in space, with safety being the top priority. The first demonstration of DRACO could happen in 2027, according to NASA.
Daniel Dumbacher, executive director of the American Institute of Aeronautics and Astronautics, called nuclear propulsion a big step forward for space exploration.
Missions to Mars naturally include myriad risks to human health, he said, but nuclear technology could limit some of the consequences, including the psychological toll on crews confined to confined spaces.
«There’s the psychological aspect of being away from home for so long,» Dumbacher said. “How does the human mind deal with being in something the size of a school bus for months on end? How do we keep the mind entertained? How do we keep morale high? All of these challenges grow exponentially when you go to Mars, so shortening travel time is a big deal.”
Blueprints for a nuclear rocket motor were initially drawn up in the 1960s. But the program stalled after the 1979 Three Mile Island accident and the 1986 Chernobyl disaster turned public opinion against nuclear technology. .
Now, Nelson said, there is more appetite and political will to explore alternative fuels.
Tompkins said the promise of nuclear propulsion was there in the 1960s, but the program was never able to reach its full potential. She said that this current environment is the «right time» in history to evolve technology to the next level.
“When I go back and read the reports from those days,” he said, “I am continually reminded that we can all stand on the shoulders of giants.”