The Nuclear Salt Water Rocket - Possibly the Craziest Rocket Engine Ever Imagined. 

Fly S.A.F.E.: Surfing Atop Fisson Explosions

"non-stop Chernobyl", "weapons grade uranium", "fly safe". Welcome to the CIA watchlist, bois.

Engines, % C, and "No known reasons it wouldn't work" - What a time to be alive.

Honestly, at this point in history, THIS is the best engine we've got for REAL interplanetary travel.

Kerbal Space Program 2 developers: "Write that down, write that down!"

"How is the engine running?" "Not great -not terrible."

"900 times the energy of TNT" Excellent

"Ruin your day" Early interplanetary humanity is going to be *LIT*

"Non-stop Chernobyl" sounds like a perfect angle for the pitch to the investors.

- So, is this a great idea or a terrible idea? - Yes

"So you know what we've thought about?" "Please don't tell me you want to use nukes as a propulsion method again" "Oh no not nukes, we want to make a non-stop Chernobyl"

"what if Project Orion but the explosion is continuous"

This thing somehow manages to be even more insane than the one where you ride a constant chain of nuclear explosions on top of a giant steel plate

I love it! 😍

And thus was born humanity's improbable stone age stellar empire, built upon nothing but hubris and a love of things that go boom. When it comes time to join the interstellar community, we may find that we're the Klingons. Ad Luna! Ad Ares! As Astra!

"Non stop Chernobyl". Sounds like a name for a heavy metal band.

"I went to Jupiter and back in 6 months, riding a continuous chernobyl-like atomic bomb". There won't be a more badass quote, ever. Period.

"Open cycle nuclear reactor" Well. This is it. Nothing will ever excite me as much as this. My ChE and NE nerding combine to this one horrendous, wonderful beast.

5:30 "this isn't your usual slow reaction" i mean it's kinda to the nuke what a conventional rocket is to a bomb, right? like a nuclear runaway explosion that just keeps going with one end open

OK, the science says yes, the engineering says yes, and the mere fact that we're genuinely using units like "1% of the speed of light" makes me say Yes Yes Yes! Another fascinating vid, Scott, many thanks. (NB, can I nominate that the SI unit for 1% SoL be called the 'Manley'?)

Project Orion: "Let's throw megaton-class nuclear bombs out the back and literally blow this thing to Mars." NSWR: "Hold my beer."

He says “Fly Safe” while describing his magic nuclear bomb Chernobyl flying carpet...

I'm not sure I like the idea of being inside a rocket that has nuclear explosions continuously going off behind me, but I do like the idea of going to other star systems in decades instead of millennia.

The fact that this genuinely feels like the beginning of stuff like this being taken so seriously and potentially being worked on in my lifetime alone is enough to make me happy during this rubbish pandemic times. Love that a fellow jock is the go to space guy also btw 🤘🏼🏴󠁧󠁢󠁳󠁣󠁴󠁿

"There's a more powerful version, where instead of using reactor grade Uranium it uses WEAPONS grade uranium" Because of course there is.

When you look at it there goes another steam engine.

”A drive’s capability as a weapon is directly proportional to its capability as a drive” - The Expanse

The 90% enriched version is a warship drive. Not only does it have the sheer power to make the sorts of burns you might need while packing the mass of your offensive and defensive systems, it's also a weapon in its own right. Exhaust velocities in the thousands of KPS, AND it's radioactive as hell? The Kzinti Lesson says hi :P Plus, it's fuel efficient enough that if you're willing to settle for a "mere" 1,000 KPS of delta V, your tankage would be relatively small and easier to protect.

“It’s like Chernobyl but in space”

"Dr Von Braun, let me introduce Dr Strangelove. Oh, you've worked together before?"

Meanwhile at the Universal Atomic Energy Agency, the alien in charge of space decontamination just had all 4 of his hearts go into cardiac arrest.

"My father is a firefighter" "Wow that's badass" "Uh, my father it's a soldier then" "Doesn't he fear death?" "Pfft, my father rides atomic bombs to Jupiter and back every six or so months, and that's only the way he travels to his job"

I'd rather see the worlds supply of weapons grade nuclear material used in a space ship than a bomb.

"there's some things you can only really do in space" "oh yeah, name on" this.

From what I can tell, it's probably the motor that Tintin's rocket used :D

As I understood it from having read up a bit about this idea, the fuel tanks don't need to have boron (or other control rod material) inside them, though the tanks were made of a high-boron metal alloy, or at least a layer of boron in the tank walls. But the main way of preventing criticality occurring in the fuel tanks was simply geometry - the tanks would be made long and thin, with relatively large gaps between all the tanks, a bit like how nuclear reactor cores are made of lots of separate long thin fuel rods rather than one massive block of uranium. There would also be lightweight non-absorbent filler material in the gaps between the tanks to prevent the water pooling anywhere inside the whole structure in event of any tank springing a leak. As to the chemistry, uranium tetrabromide seems like a bit of an odd choice to me - especially as a solution in water would be at least partially hydrolyzed into uranyl ions and hydrogen bromide, the latter making the solution strongly acidic. The only way to inhibit this hydrolysis would be to keep the pH low with another even stronger acid, so either way, uranium tetabromide solutions would be corrosive at the very least, as well as probably unstable. The sources I read mentioned using uranyl nitrate or plutonium nitrate: These make a lot more sense, since all nitrate salts are water soluble, the solutions are stable and not appreciably acidic, and can be made much more concentrated than bromide salts if necessary.

I like this concept and with that exhaust nobody will ever tailgate for long.

Phrases to leave out of the promotional materials, #431: "So it's a non-stop Chernobyl in space."

The "fly safe" in the end sounded like a threat. 😬

ah yes I too measure my engine power in chernobyls per second

Having read Zubrin's paper, there seems to be a pretty obvious show stopper in this design. Zubrin goes to great lengths to explain how a critical mass could be maintained in the cylindrical part of the engine(plenum) due to the fact that water is basically incompressible and would maintain a steady flow rate. But then he wants almost all the actual fission to happen in the nozzle where the propellant is more spread out and is no longer a critical mass. Because uranium atoms only release a limited amount of neutrons when they split there is simply no way to generate enough neutrons in the plenum to split the required number of uranium atoms in the nozzle, and if you had enough uranium in the nozzle where the propellant is spreading out to maintain a critical mass the plenum would go up like a bomb. Also you cannot heat the water in the plenum enough to turn it into steam, because then you have to take gas laws into effect where increased temperature requires either higher pressure(which would result in the flow going the wrong way), or increased flow speed as you go down the plenum, resulting in the critical mass being lost and the chain reaction ending even before you get into the nozzle. Because heavier molecules such as water and uranium require a much higher temperature than straight hydrogen molecules to reach the same ISP, I am extremely skeptical that any attempt to build this design could actually reach the ISP levels of a nuclear thermal rocket, never mind the tens to thousands of km/s exhaust velocities Zubrin speculates about. I would love to be proved wrong, but this design seems to be a classic case of using math to get answers to a different question than you are actually asking.

Hearing “1% the speed of light” is just...nuts. I can’t wrap my brain around that

I don’t want to imagine what a “hard start” would look like for this

Scott Manley boosts my passion for hard sci-fi. Thanks

3:16 "This is obviously a technical challenge, but that's a whole nother video" Okay so when is that coming?

"non-stop Chernobyl" ... "depending on how you do your math" ... "Fly safe!"

Right, time to kickstart this project!

You can also get the water flow rate to increase by simply restricting the flow cross section after the boron lined section of pipe, sort of like a venturi in a carburetor but with positive pressure at the inlet rather than positive pressure. You could even feed in a more concentrated nuclear fuel-water mix to better control the rate of reaction.

5:40 So they run it at melt down levels while pumping water through it so it all goes ZOOM instead of BOOM

9:50 "it's like a non stop Chernobyl going on" well sign me up then

Oxford English Dictionary lists that the slang word salty means: angry, irritated or hostile. This propulsion system is driven by the power of irritation, anger and hostility.

I hold not an ounce of irony when I say: Ok this is epic

KSP 2: We're going to postpone the release one more time for the sake of continuous Kernobyl.

"Fly safe" seems less appropriate when discussing nuclear rockets

5:05 this design is so insane, the entire fuel tank would have to contain some kind of Boron foam to absorb neutrons and as the graphic shows all the plumbing would also have to be filled with boron tubes

it truly saddens me that we have these possibilities to make engines like this enabling access to the entire solar system and there isnt a single group actively exploring making such a thing.

If it's crazy and it works, it's not crazy.

Certain chillies have the same effect in my exhaust nozzle.

Thank you for excellent content, Scott! I recently discovered your channel and I'm so happy that I did!

Scott, I learn something from every video you produce. Thank you!

This is actually a viable Torchship.... quick tell ELON about it.

"Non-Stop Chernobyl" is a great band name.

That design is crazy. Such a rocket engine would need to be designed to be much smaller so that the craft operates as a torch ship. Because even if you can only generate a small thrust, it changes life on board dramatically.

That was really well explained. Thanks!

Funny enough, the first time I heard of the Orion project I did ask myself: why not use a constant explosion instead of individual ones? Looks like somebody did think of that, 30 years ago.

"I'm Scott Manley, explode safe 🚀🔥💥💥💥💥" xD

What a fascinating video! Thanks for this Scott!!

This is the coolest rocket video ever - thank you Scott Manley! Finally all the sci-fi nuclear (implied or explicitly stated) rocket engines make sense!!!

"Stage separation successful, Chernobyl thrusters ignition in t minus 10, 9, ..."

Okay, that was a cool video. This is the first time I can remember in my life feeling like anything measured in light years distant maybe worth paying attention to.

As always your videos reach an amazing mix of science fiction and the physically possible. Thanks for giving us a reason to dream.

Great video Scott! Perhaps you could do a follow-up covering the fission-fragment rocket?

OMG! Someone finally referred to the Nevada Test Site as "Jackass Flats," it's correct name. Thank you, Scott.

The specific impulse figure is so insane, it’s got to be done! Space here we come!

Always enjoy and learn from your videos. Would love to see a follow-up video to this that references how realistic the "Pathfinder" shuttle using a Nerva engine from the show "For All Mankind" is.

"Its like a nonstop chernobyl going on" :D probably not the best marketing

Thermal taps from the external reaction could literally power the rest of the ship. Why let all that radio active energy go to waste?

"It's like Chernobyl but in space" Chernobyl: Am I getting a sci fi sequel?

"HAL! Throttle down the engine..." "I'm sorry, Dave, but I WANNA GO FAST!"

This is astonishing marble of engineering. Loved the concept. Hope it'll never get abandoned like the "Nerva" engines.

As a professional nuclear rocket scientist, I approve this message.

NSWR: the closest we could get to interplanetary torches in any near future vehicles. Also extremely scary.

Love the video - and the always well placed sarcasm!

That was such a cool video Scott! Wow that was freaking amazing. You know some smart kid is actually going to perfect this and send us on our way with the 90% uranium mixture. Star Trek here we come!

Scott Manley is the one youtube channel I'm still coming back to after years and years. You're always relevant. Because space travel will always be relevant.

Have done a presentation at a Sci Fi convention about these drives. They're my favourite "You think NERVA rockets are scary? What to you get a load of one of THESE babies!" rockets.

I really enjoyed this video. Very well done 👍

Most interesting engine video in a while!!!

"comes from solar panels soaking up the sun" Phrased like that it sounds like solar panels are some kind of doomsday device.

So essentially, not only is your fuel hypergolic, it's a fission bomb.

I love your videos and am glad you do them.

5:50 - "Liquid Chernobyl" has a nice ring to it.

"the majority of the reaction will happen where you want it to" ... and the small minority will be occurring where?

loved the explanation thank you

Thanks, really interesting option for future interstellar probes -most realistic I've seen. Thanks for a good explanation.

I bet in my lifetime we'll have a nuclear version of the Titanic or Hindenburg on a trip through the Astroid belt to Mars

We used to sail across the Atlantic with just the wind and we look at these people with sails like future generations are looking at us being creative with gravity assists.

Really loved it man ❤️!

Hi Scott, and happy new year to you. That was the most thrilling video you have made so far. The thought that it could actually, definately maybe, be done give goose bumps. 👍🏻🎆. 🇩🇰🙋🏻‍♂️🌞👩🏻‍🚀🇺🇸

All I can see is Yosemite Sam: "Woe ship, WOE SHIP! when ah say's WOE, Ah means WOE!" :o)