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The Pentagon Is Working on a Nuclear Thermal Rocket

Caroline Delbert
Photo credit: NASA

From Popular Mechanics

  • The next space race could be to put a nuclear satellite in cislunar space.
  • The U.S. military and NASA both have projects in the works, as does China.
  • Nuclear reactors could be remotely assembled from pieces launched one at a time.

The Pentagon is working on a “nuclear thermal propulsion” engine with the goal to be able to drive satellites around in space, The Daily Beast reports. This seems to be a multi-motivated effort to thwart other countries’ space progress, better mine resources from the moon, and also serve as a weapon. Like a well-rounded athlete or entertainer, the nuclear thermal propulsion system aspires to be a triple threat—literally.

If this sounds somewhat sinister, you’re not wrong, although it’s not any more or less villainous than any other defense thing. But that name...

“DARPA’s budget request for 2021, which the agency released in early February, asks for $21 million for the ‘Demonstration Rocket for Agile Cislunar Operations’ program, or DRACO,” The Daily Beast says. Cislunar refers to the area between Earth and the moon. Draco has strong malevolent Malfoy energy, but also just means “dragon” in Latin.

The technology involves a small nuclear reactor mounted on a rocket, where the reactor produces thrust by pushing hot or burning material out of a rear opening. Current satellites have very small thrusters that serve almost exclusively to adjust altitude, and these are often electric, because satellites can gather solar energy for much of the year. Even so, the bursts are typically budgeted rigidly because of the opportunity cost of spending fuel at all.

A highly mobile and powerful satellite thrust system is something new, at least if it gets to the execution phase. Being able to navigate in orbit has been a moonshot goal for all the global powers for a long time; so many ideas exist at many levels of development. There are inherent limitations to vehicles that are meant to stay in orbit and interact with Earth’s surface. And although the moon obviously orbits Earth and stays in a predictable pattern—our original satellite!—that orbit is hundreds of thousands of miles further away than most of the satellites in orbit.

NASA’s IBEX satellite is exceptionally high and near the moon at about 200,000 miles. Most of Earth’s communications satellites are in an orbit about 22,000 miles up, which is called geostationary orbit because of how these satellites appear to “stay” with the Earth as it spins. The area between 22,000 and about 239,000 miles is pretty empty, and this is where the U.S. and Chinese militaries and space services imagine their nuclear-thrust cislunar vehicles.

The Daily Beast says the vision for these nuclear reactors includes being assembled, in the Johnny Cash tradition, one piece at a time. This spreads the heavy payload over many rocket launches, but requires the reactor to be put together while in space. The human-occupied International Space Station orbits at around just 250 miles up, and assembly of a nuclear satellite engine would take place far, far above that, so we’d need some kind of autonomous or remote assembly.

Today, NASA and the military believe this technology is a good complement to our plans to return to the moon by 2024, for example, and the increase in global government and civilian rocket launches. It’s not hard to imagine a future where companies have mines on the moon that are regulated by some kind of cislunar police force. Of course, just because it’s easy to imagine, that doesn’t mean it’s a good or feasible idea.

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