Engineers Are Developing Nuclear Spacecraft Again. NASA Says We're Going to Need Them

NASA has teamed up with DARPA, the Pentagon’s research arm, to revive an idea that failed 50 years ago: developing nuclear rockets. But why do we suddenly need nuclear rockets?

An idea from the 1950s. The U.S. Air Force initiated research on nuclear-powered intercontinental missiles under Project Rover. This development later transitioned to the space sector with NASA and the Atomic Energy Commission (AEC) collaborating on the NERVA (Nuclear Engine for Rocket Vehicle Applications) project.

The concept was relatively straightforward. The idea was to pass liquid hydrogen through a nuclear reactor to heat it, and then expel it through the nozzle of a rocket for thrust. This design, known as a nuclear thermal propulsion (NTR) rocket, offered the potential for unprecedented fuel efficiency.

But the construction of nuclear spacecraft turned out to be highly complex in practice. Extreme temperatures, hydrogen corrosion, and the absence of gravity made every step more difficult. NASA terminated the NERVA project in 1973 after 23 prototypes, when the space agency shifted its focus to low-Earth orbit in its space program.

Say hello to DRACO. To address national security concerns related to China’s progress in space, DARPA decided to resurrect the concept. This led to the initiation of the DRACO (Demonstration Rocket for Agile Cislunar Operations) project, a collaborative effort between DARPA and NASA with Lockheed Martin as the primary contractor. The $500 million contract, approved last year, requires the launch of a technology demonstrator by 2027.

DRACO offers unprecedented speed and efficiency, aiming to become the first rocket capable of traveling to Mars in three to four months, instead of the typical six to nine months. What sets it apart from the prototypes of the 1960s and 1970s is its use of a new type of fuel, or low-enriched uranium (HALEU), to minimize risks and regulatory complications.

Joe Miller, the vice president of BWXT Technologies, the company responsible for constructing the experimental vehicle’s reactor, told Ars Technica that it has created its “own internal formulation of the nuclear fuel” that can withstand reactor temperatures without cracking. Nevertheless, project engineers have had to resolve issues similar to those that affected the NERVA program, such as hydrogen corrosion and material spalling from the reactor core.

Why do we need nuclear rockets? The use of nuclear rockets can significantly improve space travel by increasing speed and efficiency. This reduction in traveling time through space can lead to decreased radiation exposure and reduced need for supplies on journeys to Mars, thus enhancing astronaut health and safety.

Moreover, the potential benefits of nuclear rockets extend to the establishment of a new system for transportation between the Earth and the Moon. They could serve as “space tractors” for moving cargo between these two celestial bodies.

Nevertheless, there are concerns with the project and controversies surrounding it. Some question the necessity of nuclear spacecraft when chemical alternatives, such as cryogenic propellants, are already in use and are advancing. Additionally, others worry about the potential weaponization of space as a result of these technological developments.

This article was written by Matías S. Zavia and originally published in Spanish on Xataka.

Image | Los Alamos National Laboratory | DARPA

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