Lockheed Martin [NYSE: LMT] has won a contract from DARPA (Defense Advanced Research Projects Agency) to develop and demonstrate a nuclear-powered spacecraft. The in-space flight demonstration of a nuclear thermal rocket engine vehicle will take place no later than 2027. The project is called Demonstration Rocket for Agile Cislunar Operations (DRACO).
DARPA partnered with NASA’s Space Technology Mission Directorate on the DRACO project.
They will use the TRISO pebble bed fuel made by BWXT.
The agreement is structured as a milestone-based other transaction authority agreement with a total value of $499 million, said Tabitha Dodson, program manager for DRACO at DARPA.
Officials did not disclose the thrust the DRACO engine will produce, although Calomino said it will have a specific impulse, a measure of efficiency, of about 700 seconds. That is significantly higher than even the best chemical engines (260-460 ISP. most around 300-340) although the design goal for NTP systems is 850 to 900 seconds.
NTR (Nuclear thermal rocket) propulsion offers a high thrust-to-weight ratio around 10,000x greater than electric propulsion (ion drives) and with two-to-five times greater efficiency than in-space chemical propulsion.
NASA will lead the design of the nuclear engine itself, which will be integrated into a DARPA experimental spacecraft. Spacecraft would operate at a minimum altitude of 700 km, maybe as high as 2,000 km, says Melroy.
— Jeff Foust (@jeff_foust) January 24, 2023
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A nuclear rocket engine has been tried before and abandoned due to the high cost of getting it into space. 2027 is science fiction. To meet that date would take trillions of dollars in rapid development of the reactor and support systems. You just can’t take a PBR and blast it into space.
Wait four years and we see what happens. DARPA and government have provided the funds to Lockheed, BWXT Technologies
The cost of getting stuff into space using chemical rockets is down pretty massively.
This sounds like a satellite-scale testbed given the 70-200km altitude listed…..
Given the other nuclear powered satellites presently in orbit….. That should be quite doable….
Now, a ‘Starship’ type upper stage with nuclear engines? THAT will take a decade plus……. Esp since it would be NASA not SpaceX building it (can’t do the light the fuse and see if BOOM development cycle with a nuclear engine unless you build the whole thing in space)…..
This is the future I was promised so long ago.
I hope they plan to operate from lunar orbit.
Onward and Upward!
Lest we forget …
A ‘nuclear rocket’ engine is a HEAT engine, ultimately. A reactor core containing enough ceramic-coated nuclear fuel is brought to criticality; it rises in temperature (but helpfully, also expands, working passively against BOOM super-criticality) to a very high level. ‘Cooling’ it — but actually doing the propulsion work — is a blanket of very high pressure hydrogen. The hydrogen is heated to basically the same temperature as the core’s pebbles, and exhausts out the nozzle at supersonic speeds.
Being heated, ‘supersonic’ is also elevated. So, the ultimate limit is the containment pressure of a device that is very likely to exceed 2,500 K in full throttle operation. There really is nothing special about the thrust itself, just very hot expanding hydrogen gas.
For simplicity and to keep mass down, I don’t imagine there’s any kind of post-heating ionization and electrical discharge to ‘after-burner’ further accelerate the expanding hydrogen. Its a nice idea, and if one has a magic wand that can create outrageously abundant electricity at no weight penalty, well … that’d be in there too. But the mass penalty is terrible in converting nuclear byproducts to electrons.
So… core gets hot, heats passing hydrogen, and jets out the rump at supersonic velocities.
Rocket engine. 101.
Note that ultimately there’s very likely WAY mmore nuclear energy content in the NERVA engine core than there’s hydrogen to use as coolant-and-propellant. Its a tradoff. We might want ‘only enough’ nuclear WuWu to heat the onboard H₂ and very little extra, but … well … its nuclear, so that’s not an option. Nuclear reactors work best when ‘topped up’ with fuel, and decidedly worse when the fuel breaks down.
Oh well. Just money, I guess.
THERE ARE a lot of good things, however about it. Hydrogen!
Talk about a ubiquitous and inexhaustible resource! This is good.
Getting it up there in MEO (2,000 km, to link to the article, tho’ they didn’t say so) is a job for the chemical space tugs. Methane breathers, a la Musk’s Magnificent Rocket, specially adapted just for cryogenic hydrogen comporting seem like a really good fit. Liquid hydrogen is insanely bulky, so needs big tubs. Cans. Huge cans.
Indeed, since Tsiokovsky’s Rocket Equation doesn’t propose that the RATE of rocket burn impacts the ultimate speed of the projectile in the end, a gob-smackingly-ridiculous cryogenic six-pack of cryo-hydrogen tankage could be lofted and guided to the international refueling station’s hungry fuels facility … every day, 24–7. I could see that.
Then these ‘nuclear’ rockets would work quite well. Shuttling hydrogen around like giant petrol space trucks. Doing deliveries all over MEO, for fleets of interplanetary or even just ‘cis-Lunar’ shuttles and surveyors. Science craft.
Its a pretty vision. Nuclear optimizes this from a position of remarkable simplicity.
Hot rocks heating hydrogen gas.
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Tho’ of course not commented upon, there is a wee bit of a problem though.
Radiation. LOTS of radiation. Lots of neutrons, gamma rays. Lots and lots an dlots and lots.
This may well be why the ‘minimum 700 km’ flight level was cheekily stuck in at the end. The “solution to pollution is dilution”, as the saying goes. Or … thinking more like down-here-on-Planet-Dirt … the nominal solution to the belchings of a nasty old chemical industrial factory are vented using much, MUCH taller smokestacks. Shooting the nastiness up high enough that atmospheric mixing will DILUTE the pollution sufficiently that those down-wind aren’t overly poisoned.
Sure, as anyone in nuclear science knows, you CAN shield the likes of ‘gamma’ radiation with a sufficiently thick heavy mass. They do it all the time on terrestrial reactors. Heavy, thick, strong, lots of it. Now, what single word of those 4 words is compatible with the gossamir flitters that are engineered to work in space? Errr… none of them.
Same goes for the neutrons, actually. Then tend to burrow through most everything, and right outside. Oh, there are good neutron absorbers, but they ‘wear out’ as their elements are transmuted by absorbing all those very same neutrons. What’s a scientist to do?
Ah! Dilution! Fly the nuclear birds higher up, giving far, far more distance between their lethal cores and the top of the atmosphere. I remember reading about one particular nuclear test shot — in atmosphere, in Nevada — where the 25 kiloton bomb was lifted by rocket to 250,000 feet (50 miles, 80 km), and UNPROTECTED volunteers were positioned directly under it, with no shielding eexcept dark-dark sunglasses. They experienced a ‘flash of heat’ and that was that. Basically no radiation, and certainly not enough to be remarkable or worrisome.
See? Dilution. Dilution-by-distance. Still … Hundreds of megawatts of nuclear radiations is something not to sweep under the rug. It would have markedly BAD consequences for passing spacecraft that get too close. Not just ‘bad from heating’, but much further away, bad for electronics.
So, Idon’t know. We might necessarily have to limit the nuclear rocket deal to much-further-away. Like 10,000 km, about ¹⁄₄₀th the way to Luna. And beyond. The transit from Terra to Luna of course could easily be done ‘all the time’ in both directions via nuclear propulsion. Just have to have a LOT of those Musk-powered cryogenic hydrogen cans shuttled to and for.
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So there you are, goats! Reasonably positive!!!
Great except for the radiation. And refueling. And radiation.
Did I mention radiation?
⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
Front end looks like the bus/crycooler from LM’s Cislunar Transporter, which is a LOx/LH2 moon tug.
How many prototypes and test rigs would be built and tested to introduce a new gas generator or staged combustion rocket engine, lika, lika, lika raptor?
How many 19.9% enriched TRISO frit reactors BWXT going to get to build to get it right, or are they going to be in a situation where the prototype disappoints?
A rocket engine probably worth a bit more than it’s weight in nickel to SpaceX, assuming it will fly again. This little reactor is going to be priceless….. millions of dollars, likely thrown away after one use…. for what mission that we cannot accomplish with HydroLOX?
Why would you throw it away? It’d be great for repeated trips between Earth and Moon.
You’re overestimating the anticipated reliability. Look into how the Nerva reactors eroded as they fired and sent much of the fuel element material out the nozzle over the testing. Additionally, the trips between the Earth and Moon have been demonstrated to be within the realm of conventional rocketry. Why use an experimental, intense point source of neutrons for this?
If built, likely to fire a few time and be retired. NTP is a nightmare; doesn’t give enough bang for the pain in the butt.