The PDFs here have a lot more information: <a href="https://sam.gov/opp/af490b568d2a438498afa1e80bce63e5/view" rel="nofollow">https://sam.gov/opp/af490b568d2a438498afa1e80bce63e5/view</a><p>A few takeaways; they intend for such an engine to eventually support long duration human spaceflight (going to Mars.) The propellant for the NTR engine to be liquid hydrogen. One of the problems DARPA anticipates with using such an engine for such a mission is needing to store liquid hydrogen longer than the present state of the art.<p>The PDF doesn't seem to mention it, but I think the Advanced Cryogenic Evolved Stage (ACES) is probably relevant to this project. Does anybody know what kind of duration they expect to get from ACES? I'm not sure but I think it's weeks, not months.
We have known how to build working NTRs since before the moon landings. They are a proven technology but we decided is was not worth the risk to fly them.<p>What changed? Or will this rocket stay firmly on the ground?
If I remember correctly, SpaceX would be happy to experiment with nuclear-thermal propulsion but cited the lack of a engine test stand as reason why they aren't actively working on it. I'll see if I can find a quote for that. I am rather sure that it was by Gwynne Shotwell, COO of SpaceX. (Edit: progress! I think it's in a talk by her at MIT Road to Mars 2017. Too bad I cannot find a recording of that).<p>NERVA is another term to search for if you are interested in nuclear-thermal propulsion.<p><a href="https://en.wikipedia.org/wiki/NERVA" rel="nofollow">https://en.wikipedia.org/wiki/NERVA</a>
I really hope this gets off the ground - literally and figuratively.<p>NTRs would be a game changer for Sol exploration and open up some real serious options for things like intercepting interstellar objects.
Link with anchor <a href="https://orbitalindex.com/archive/2022-05-25-Issue-170/#darpa-moving-forward-with-draco-nuclear-thermal-engine" rel="nofollow">https://orbitalindex.com/archive/2022-05-25-Issue-170/#darpa...</a>
Presumably this is a solid core design and since these would never fly in the atmosphere anyway, I've always thought that going all in on nuclear salt water engines would be the way to go [1]. These things are so high performance, I bet even a small/micro one could enable tic tac levels of performance, buts that just a guess.<p>[1] <a href="https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket" rel="nofollow">https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket</a>