Orbital Nuclear Thermal Propulsion Demo By 2025

DARPA is funding a nuclear thermal orbital flight demonstration by 2025. The Demonstration Rocket for Agile Cislunar Operations (DRACO) program is to demonstrate a nuclear thermal propulsion (NTP) system on orbit. NTP uses a nuclear reactor to heat propellant to extreme temperatures before expelling the hot propellant through a nozzle to produce thrust. Compared to conventional space propulsion technologies, NTP offers a high thrust-to-weight ratio around 10,000 times greater than electric propulsion and two-to-five times greater specific impulse (i.e. propellant efficiency) than chemical propulsion.

The DRACO program will have two tracks. Track A will include the baseline design of a NTP reactor and culminate in a baseline design review. Track B will include development of an operational system concept to meet operational mission objectives and a demonstration system design that is traceable to the operational system but focuses on demonstrating the propulsion subsystem. Track B is anticipated to culminate in a technology maturation plan review for the demonstration system.

The three prime contractors are General Atomics, Blue Origin, and Lockheed Martin.

Rapid maneuver is a core tenet of modern Department of Defense (DoD) operations on land, at sea, and in the air. 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 propellent efficiency, respectively. DRACO’s NTP system has the potential to achieve high thrust-to-weight ratios similar to in-space chemical propulsion and approach the high propellent efficiency of electric systems. This combination would give a DRACO spacecraft greater agility to implement DoD’s core tenet of rapid maneuver in cislunar space (between the Earth and moon).

Phase 1 of the program will last 18 months and consist of two tracks. Track A will entail the preliminary design of an NTP reactor and propulsion subsystem concept. Track B will produce an Operational System (OS) spacecraft concept to meet mission objectives and design a Demonstration System (DS) spacecraft concept. The DS will be traceable to the OS concept, but specifically focus on demonstrating an NTP propulsion subsystem.

“This first phase of the DRACO program is a risk reduction effort that will enable us to sprint toward an on-orbit demonstration in later phases,” added Greiner.

General Atomics will perform the Track A reactor development work. Blue Origin and Lockheed Martin will independently perform the Track B work to develop OS and DS spacecraft concept designs. DRACO’s Phase 1 is expected to inform follow-on phases for detailed design, fabrication, and on-orbit demonstration. Any follow-on phases will be solicited by DARPA in a future announcement.

The General Atomics SNAP-10A reactor has been the only U.S. nuclear power reactor launched into space, for which General Atomics was directly involved in nuclear fuel testing and characterization.

In 2021, the Demonstration Rocket for Agile Cislunar Operations (DRACO), formerly known as “Reactor on a Rocket (ROAR)” had $21 million in funding. This is up from an initial $10 million in 2020. DRACO “will develop and demonstrate a High-Assay LowEnriched Uranium (HALEU) nuclear thermal propulsion (NTP) system.” NASA is working on similar nuclear thermal propulsion rockets, which use low-enriched — between 5 and 20 percent — uranium-235 (U-235). U-235 is the basic nuclear fuel for commercial light-water reactors when enriched to between 3 and 5 percent; the Navy’s nuclear reactors use U-235 fuel enriched to 90 percent.

There have been decades of ground tests for nuclear thermal propulsion. This will be a far smaller system that will not launch from ground to orbit. The goal is for better orbital operations.

SOURCES- General Atomics, DARPA, Breaking Defense, CNET
Written By Brian Wang, Nextbigfuture.com

18 thoughts on “Orbital Nuclear Thermal Propulsion Demo By 2025”

  1. NERVA was back in the good old days when the USA could design and build a military jet in a couple of years. These days it takes a couple of decades.

  2. DARPA has a reputation for getting things done fast. We had built nuclear engines before. I remember two programs: KIWI and NERVA. A nuclear engine can be easier to build than a chemical engine because there is only one working fluid and you can run it at a lower temperature and still get a good ISP.

  3. Private companies have been designing nuclear reactors for decades, I don't see why with enough will they wouldn't be able to design nuclear rockets. Going anywhere deep space will not be cheaper with chemical rockets, just think about the fueling infrastructure needed to get to Mars with chemical rockets, in time, nuclear rockets will become competitive in going to orbit and suborbit as well.

  4. They are talking about launching in 2025? If that's even close to realistic they must be ready to start building the final design already.

    I'd be stunned if a government program to build a nuclear space ship could get from "it's finished" to "launch" inside a couple of years of checks, double checks, triple checks. (Ghost of Hubble just for a start.)
    And I'd be even more surprised if they could go from a completed and signed-off design to a completed unit inside a couple more years. Maybe building the 37th unit, not the FOK.

    So that works out to them being pretty much at the signed-off design stage this year.

  5. If it can be made to work with Uranium enriched to just under 20% U235 the restrictions are far less. That is enough below weapons grade that the regulators are much less paranoid about it.

  6. hah! what a perfect cover for an evil, secretive yet-oh-so legendary, world-power-craving techno-syndicate — minimal oversight and a Director (Victoria) that gives off a definite Blofeld vibe (i know there is a new director since). Hope that the esteemed US Space Force has been preparing for such an eventuality.

  7. DRACO? seems too close to those old Bond villians (draco/ drax). Always figured that DARPA was too productive and creative to be an actual government agency (sarc).

  8. not convinced on prioritzing against this, for re-usable solely. Good time to push forward work on getting us between cis-lunar stations and everywhere else in the inner solar system — solar sails and exotic large-payload propulsion systems are certainly way-far behind. We want to be with trojans in 2050? we need this in 10 years.

  9. The complexity of coordination and regulating and creating achievable/ quantifiable milestones for this will make the ISS and shuttle program seem like a cubesat launch — though, DARPA..

  10. We have the technology. What we need is mass production. We don't have to build hundreds, just twenty or so would make each unit so much cheaper. A nuclear upper stage could send orbiters to the outer planets.

  11. There will be restrictions placed on private companies. Just getting the highly enriched U235 would be a problem.

  12. Right now this technology looks like a regulatory quagmire. Government will need to untangle that mess and push forward with some experiments, also making regulation more propitious for private companies to use it, to make it really interesting.

    Given the hassle, I'd say as it's not worth the effort for any private company working on making space launchers cheaper with reusable rockets, which are actually much more needed.

    Gee, even VASIMR looks more promising an usable right now. Basically by being free of similar hurdles and being ready for deployment, as soon as someone pays for it.

  13. Hopefully they will keep it simple and cheap. We have already built nuclear rocket engines so this shouldn't need billions in R&D. High Thrust Ratio isn't that big a deal once you are already in orbit. What they need to focus on is high temperature which translate into high ISP and low mass ratio.


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