In an ambitious stride towards space-based nuclear propulsion, the US government is launching a project with NASA to take humanity to Mars via nuclear rocket engines. Set to launch four years from now, this ground-breaking project will see the first-ever nuclear-powered engine rocket into space. Though the rocket will be conventional, the payload it’ll send to orbit is anything but ordinary.
The partnership between NASA and the US Department of Defense aims to push the boundaries of space travel, committing a significant investment of around $300 million to design an innovative propulsion system for interstellar transportation. Anthony Calomino, the engineer spearheading NASA’s space nuclear propulsion program, said, “NASA is looking to go to Mars with this system,” stressing that the project will provide the necessary groundwork for future space explorations.
Conventional chemical propulsion, although great for launching rockets from Earth, is quite inefficient for navigating the solar system due to its excessive fuel consumption. Wernher von Braun, the post-WWII German defector and engineer, had acknowledged the potential of nuclear thermal propulsion long before humans landed on the moon. He inspired the inception of NERVA (Nuclear Engine for Rocket Vehicle Application), which was later canceled to finance the Space Shuttle.
Nuclear propulsion involves rapidly heating a propellant, likely liquid hydrogen, in a nuclear reactor. The expanding gas is then expelled through a nozzle, generating thrust. Despite its simplicity in theory, its actual implementation for in-space propulsion, including the safe launch of a nuclear reactor into space, presents formidable engineering and regulatory challenges.
Following years of dormancy, the US Defense Advanced Research Projects Agency sparked renewed interest in nuclear thermal propulsion technology in 2020. This led to the birth of the Demonstration Rocket for Agile Cislunar Operations (DRACO) program, aimed at efficiently moving payloads between Earth and the Moon. NASA later joined the initiative, aiming to use similar technology for Mars missions, based on the belief that nuclear propulsion is the only sustainable way to establish a Mars exploration program.
This Wednesday, NASA and DARPA announced Lockheed Martin as the primary contractor for assembling the experimental nuclear thermal reactor vehicle (X-NTRV) and its engine, in collaboration with BWX Technologies. Lockheed Martin will develop the nuclear reactor and fabricate the high-assay low-enriched uranium fuel to power it, a project valued at $499 million, according to Tabitha Dodson, the program manager for DARPA.
NASA and DARPA will split the project responsibilities, with NASA focusing on the nuclear engine development and DARPA overseeing regulatory requirements, mission operations, and safety analyses. The nuclear reactor will be launched in a safe “cold” mode, only being activated once it reaches a sufficiently high orbit.
The nuclear-powered vehicle will launch within the payload fairing of a Falcon 9 or Vulcan rocket. It will consist of a large hydrogen fuel tank, a nuclear reactor, supporting spacecraft structure, and a nozzle. The reactor will be activated once it reaches a safe orbit, heating the liquid hydrogen from just 20°C above absolute zero to 2,700 Kelvin in less than a second.
Apart from testing the nuclear engine, this experiment offers a unique opportunity to explore new ways to manage the vehicle’s liquid hydrogen propellant. The mission aims to store the ultra-cold hydrogen for a couple of months, long enough to conduct multiple tests of the nuclear thermal engine. The mission could potentially be extended if the spacecraft can be robotically refueled. It remains to be seen how these ventures will shape the development of a functioning engine that could one day traverse the vast expanses of space.
