NASA and DARPA are working on a nuclear-powered rocket that could go to Mars

By Christian Davenport,
Published by The Washington Post, 3 February 2023

When NASA’s Orion spacecraft returned to Earth from its trip around the moon last month, it was moving blazingly fast, nearly 25,000 mph, or 32 times the speed of sound.

On a trip to the moon, a mere 240,000 miles away, that’s a fine speed. For Mars, it’s painfully slow.

Using the technology NASA has, it could take some seven months to get to the Red Planet. That’s too long. Even astronauts get fussy when confined to a cramped space for months on end. And it’s dangerous. The radiation levels on a Mars mission could expose astronauts to radiation levels more than 100 times greater than on Earth.

If NASA’s going to get to Mars, it needs to find a way to get there much faster. Which is one of the reasons it said last week that it is partnering with the Pentagon’s Defense Advanced Research Projects Agency on development of nuclear propulsion technology.

“With the help of this new technology, astronauts could journey to and from deep space faster than ever — a major capability to prepare for crewed missions to Mars,” NASA Administrator Bill Nelson said in a statement. The goal, he said, is “to develop and demonstrate advanced nuclear thermal propulsion technology as soon as 2027.”

DARPA, the arm of the Defense Department that seeks to develop transformative technologies, has been working on the program since 2021, when it awarded three contracts for the first phase of the program to General Atomics, Lockheed Martin and Blue Origin, the space company founded by Jeff Bezos. (Bezos owns The Washington Post.) A nuclear-powered rocket would use a nuclear reactor to heat propellant to extreme temperatures before shooting the fuel through a nozzle to produce thrust.

Being able to move fast “is a core tenet of modern Department of Defense operations on land, at sea and in the air,” DARPA said in a statement at the time. “However, rapid maneuver in the space domain has traditionally been challenging because current electric and chemical space propulsion systems have drawbacks in thrust-to-weight and propellant efficiency.” In other words, traditional systems require too much fuel that burn at relatively inefficient levels.

The program is called DRACO, for Demonstration Rocket for Agile Cislunar (or in the vicinity of the moon) Operations.

Under NASA’S agreement with DARPA, the space agency will lead the development of the nuclear thermal engine while DARPA will work to develop the experimental spacecraft that would be propelled by the nuclear engine. The agencies hope they’ll be ready to demonstrate their work with a spaceflight in 2027.

NASA is also working with the Department of Energy on a separate project to develop a nuclear power plant that could be used on the moon and perhaps one day on Mars.

But getting to Mars is exceedingly difficult, and despite claims from NASA for years that it was gearing up to send astronauts there, the agency is nowhere close to achieving that goal.

One of the main obstacles is the distance. Earth and Mars are only on the same side of the sun every 26 months. But even at their closest points, a spacecraft would have to follow an elliptical orbit around the sun that, as Tory Bruno, the CEO of the United Launch Alliance, wrote in a recent essay, will require “a great sweeping arc of around 300 million miles to arrive.”

The path to Mars, he wrote, would require a far more efficient propulsion system with speeds that double Orion’s recent velocity. Nuclear power could provide that.

“Clearly, the faster we can complete the journey to Mars the better,” he wrote. “This means developing a much more efficient propulsion technology that could cut transit time by at least 50 percent, making the trip safer, and leaving more mass available for experiments and research gear.”

In an interview, Bruno said achieving a more efficient type of propulsion is not just about getting to space but “about transportation through space,” or moving through space from one destination to another. As space becomes a contested environment, developing a system that is far more efficient is something that the Pentagon and the U.S. Space Force have been focused on, especially as threats to satellites have grown.

Satellites usually stay in orbit over a fixed trajectory. Without the power, or propellant to maneuver, that makes them a bit like sitting ducks. But with a more efficient fuel like nuclear propulsion they could become more agile — and evasive. The need for spacecraft that can maneuver away from the enemy has become clear during the war in Ukraine.

“It’s clear that space is viewed as a critical enabler to both militaries [Russa and Ukraine],” Gen. Chance Saltzman, the chief of operations for the U.S. Space Force, said last week, according to Air and Space Forces Magazine. “Both sides have attacked [satellite communication] capabilities to degrade command and control, and there’s been a concerted effort to interfere with GPS to reduce its effectiveness in the region.”

As those systems grow, having nuclear propulsion — a far more efficient fuel than liquid chemicals — will be key, Bruno said.

“Because space is an ever-changing environment, there’s a need to relocate assets that we have, and certainly a need to extend their useful life,” he said.

The Pentagon is also searching for better ways to move “larger payloads into farther locations in cislunar space — the volume of space between the Earth and the moon,” DARPA said. But doing that, it said, “will require a leap-ahead in propulsion technology.”

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