" NUCLEAR PROPULSION IN SPACE " PROJECT NERVA SPACE NUCLEAR PROPULSION OFFICE PROMO FILM 25192

[@TheCrossroads533]

NERVA: a century or more ahead of its time! Amazing technology.

[@paulgaskins7713]

More like we are 50 years behind.

[@LuciFeric137]

​@@paulgaskins7713well said. 55 years. Very disheartening

[@jeffhyche9839]

Just think how far we would have come IF we had not abandoned this technology.

[@justcallmebrian793]

Bill Nelson just announced they are going back to that tech.

[@TheOneTrueKaliban]

The coolest thing is that part of the vid is narrated by the Lost In Space robot!

[@HPaulHonsinger]

I guarantee you that the narrator is NOT Dick Tufeld. There is some slight similarity in the voices, that much of that is the style that announcers used at that time. Here's Dick Tufeld doing straight narration of a tire commercial. kzbin.info/www/bejne/ZnzGoXqNa7OqmNE

[@alecv8249]

Now after I've wathed the movie I feel like a rocket scientist

[@danross1489]

Great! Your first test is Kerbal Space Program. NERVAs are at the end of the tech tree.

[@Live.Vibe.Lasers]

Best NERVA doc I've seen so far. I so wish we had a Phoebus sitting in LEO ready to go..

[@battlestar79]

Lol, love the name of the testing site. Time stamp 7:32 "All Kiwi power tests took place at the nuclear power development station at Jackass Flats Nevada". Sounds like a really kick ass place to kick off some rocket engine tests.

[@jakesmart6139]

I think it was named AFTER we all started doing nuke stuff there. I remember several of those critters discussing that name.

[@ShokkuKyushu]

@1:48 The exhaust can't look like that in space because it is ALWAYS underexpanded.

[@exionem]

Wow, pretty amazing the technology we had back in the 1950s. A shame we never continued developing this kind of technology nowadays. Imagine the possibilities for space travel!

[@SirShizuka]

The current technology was developed with unlimited funds in ww2, Then the technology became the private property of the oil mafia who used the corrupt government to block any research on atomic energy. They used the bomb they already had to make a little side money from dangerous nuclear power stations with minimal R&D, just enough to prevent an outcry of people demanding the cheap energy to be harnessed properly. Power stations today still use the dangerous bomb technology for power in stead of researching safer and more effective ways of using it, thus Fukushima. Any attempt to make it more effective and safer have been prematurely shut down by the oil mafia.

[@TirajAdikari]

Spewing radioactive Hydrogen/Water into atmosphere ? .. NO THANKS

[@wouterjanssens]

there's very few/no further research in safer nuclear reactors, like thorium reactors, partially because it DOES NOT PRODUCE PLUTONIUM as by-product. If you want to (ever) fuel atomic bombs (again) you need conventional fission reactors on uranium.

[@LostAnFound]

exionem See the Cash Landrum incident - we did fly it and we probably still are

[@kemalm9383]

SirShizuka it should be tested in real conditions. In a vacuum...... The numbers and real conditions will help the team.

[@simian_essence]

This video was made sometime in mid-to-late 1968.

[@thetruth7633]

1000MW actually is pretty good for such a small design

[@AuntAlnico4]

Nuclear design ?

[@alphaomega8373]

@@AuntAlnico4 That's what the video is about.

[@kyliodatter]

LOLZ. This is great sleepytime audio to fall asleep to!

[@kyliodatter]

I gave this a thumbs up for hilarity.

[@Melooo182]

+TruthAlwaysWins LOL! yeah dunno why they always gave these kind of sounds to documentaries back in the day xD

[@thekinginyellow1744]

The reason this type of vehicle was not built is because of the unreliability of the chemically fire launch vehicles. If challenger had had one of these as a payload, it would have had the same effect as detonating a dirty bomb in the atmosphere. Once we get to to the asteroid belt, if we can find (and refine) proper fuels, something along these lines might become feasible. Of course by that time, we may have ion propulsion units with a high enough specific impulse to make them unnecessary.

[@simian_essence]

What is needed is a system of safely cocooning the nuclear fuel to protect it from dispersion until after a chemical carrier rocket has put the nuclear engine and its payload into an escape trajectory from Earth. Then the fuel can be taken out of its cocoon and loaded into the nuclear engine reactor. Then the nuclear engine can be started without danger to the earth. As far as ion propulsion goes, an engine of that type should be married to a nuclear thermal engine. They would complement each other quite well on a trip to say, Sedna.

[@NameNotAlreadyTaken2]

During the 80s the Air Force did another nuclear engine study called Project Timberwind (there's a page on wikipedia). That one developed higher-temperate graphite pebble bed reactors, all-graphite turbopump fans, and just a whole lot of graphite stuff.

[@PeriscopeFilm]

+NameNotAlreadyTaken2 Fascinating! Feel free to post a link to the page on here.

You're trapped in stupid like a drowning man under ice.

[@colemcleod941]

hahaha funniest comment I've seen in a while

[@sentzeu]

The future that never was.

[@cokeforever]

And never will. Nuclear propulsion in space is a rediculous concept.

[@sentzeu]

@@cokeforever I disagree I can see us launching some probes with nuclear propulsion within the next couple of decades. For a Mars mission NASA is working on nuclear propulsion rocket. There is nothing ridiculous about it, the question is rather whether it is worth spending the effort on.

[@cokeforever]

@@sentzeu you forget about the risk of rocket delivering the nuclear upper stage to orbit exploding on launch over Florida and spraying nuclear fuel all over; this concept is mainly flawed by this issue

[@sentzeu]

@@cokeforever I think the impact of such an event would be fairly minimal. A rocket doesn't really explode, it's rather a fast conflagration. This is unlikely the hurt the integrity of the core, and while it might be fragmented on impact with water it'll remain in a localized area. The uranium fuel itself, while enriched, is still useless without a moderator present and water acts as an absorber so it is extremely unlikely for any uncontrolled reactions to take place. Uranium is also insoluble in water, both in its metallic and ceramic form, so there's no risk of polluting the water. At worst you have an expensive salvaging operation on your hands, but not a catastrophe.

[@cokeforever]

@@sentzeu rockets do not explode? see spacex crs6 if i recall correctly, the on pad explosion; you need moderator to slow the radiosctive decay not speed it up, the word "radio-active" means the element emits energy by itself...

[@ScottMana]

A friend of mine said the next NASA mars mission he thinks will be done with Ion Engines. He said a breakthrough was made by placing donut shaped magnets at the rear, 3 in all, that boosted thrust from miniscule levels to something approaching a small chemical rocket. NASA has already disclosed their intent to get to Mars and back in less than 80 days. This breakthrough is what made it possible. Such would have far greater ISP than 800 or 900 and allow for near continuous burn there and back, or at least that is the current plan.

[@ScottMana]

I was not talking about VASIMR, this however does not counter anything you said. The likelihood of them pulling this off is very low. The outlook is only getting worse, such that I would guess that by 2032 they will be more worried about local politics and other agendas than anything happening beyond orbit.

[@ScottMana]

+generic Just to clarify, the propulsion I am talking about would work with any ion, plasma or other plus or minus charged exhaust. Rings simply squeeze it down with magnetic fields basicly Z-pinching it. While I could be mistaken, NASA contracted JPL and they subbed it to a university is California. One of the professors was telling me about it. If this raises any flags, fair enough. To me, while more research was needed it looked promising and very very simple. Proof of concept was done and he demonstrated it. The thing that most hindered the program that I could see was the power draw of plasma propulsion. Existing Ion such as that on Dawn would be assisted by this as well, but 10 times almost nothing is not a lot of thrust.

[@thomashiggins1463]

i tested fuel elements and casualty protection for this at plumb brook reactor early 70s

[@gregorymalchuk272]

What all happened at Plum Brook?

[@MrGrace]

Wow! It's great to hear from people who were involved in the process. So many smart individuals!

[@TheArabsolga]

7:36 Am I hearing that right? "Jackass flats"?

[@doctorprepperisprepared]

Became part of Area 51 later, Shhhhhhhhhhhhhhhhhhh

[@sirjammer]

Jackass flats-is a biker bar around here. On a good night hundreds of hot women there, you're guaranteed not to go home alone.

[@jakesmart6139]

@@doctorprepperisprepared I don't think it became part of area 51.

[@Deltaprimal]

Admiral Preparedness actually it’s part of the nuclear weapon testing range, Area 51 is on the outskirts of that range.

[@lukestrawwalker]

Part of the Nevada Test Site, where they detonated all those a-bombs in the 50's and early 60's... Later! OL J R :)

[@Anamnesia]

Better... Stronger... Faster!!! ;)

[@ЛюсенькаРодная]

ahahahahah =)

[@RamonMedina-j6q]

NOO = A muerte por Radiación. 🥶😱

[@eye_of_purg8199]

now i have to do it in ksp

[@badreality2]

Could the nuclear core of one of these engines, be used to efficiently power/partially power the electrical systems onboard the spacecraft?

[@caav56]

Yes. Those are called "bimodal nuclear thermal rockets".

[@gregorymalchuk272]

@@caav56 I also wonder how they handle the decay heat when they don't want to fire the rocket. I assume it would use the same supplementary coolant channels that a dual purpose reactor would require for power production.

[@caav56]

@@gregorymalchuk272 Quite likely.

[@stardolphin2]

Yes, that possibility was explored toward the end of the NERVA program.

[@stardolphin2]

@@gregorymalchuk272 Basically, they tail off the propulsion gradually...which does somewhat complicate operations.

[@km5405]

wouldn't it be more cost effective to re-use the NERVA ( I imagine its a very complex and expensive part of the entire mission , also it might not be the best idea to leave solid core reactors cluttering space?)

[@xiniks]

J B deorbit it elsewhere or reuse it, sun is way to expensive. if you want to crash the stage into the sun after the mission you would need to cary more fuel for the deorbit into the sun than for the actual mission.

[@lukestrawwalker]

Space is very big... main thing is you want to make sure it's injected into a solar orbit that won't bring it anywhere close to the Earth anytime in the future... We wouldn't want a "hot" (highly radioactive) engine core reentering Earth's atmosphere and raining down somewhere. Due to the density and weight of the reactor core, it would likely survive reentry and break up, scattering radioactive materials over a wide area. A nuclear powered Soviet spy satellite similarly reentered over northern Canada back in the 70's IIRC and scattered radioactive material around, but fortunately it was in a very sparsely populated area. The RTG's (nuclear batteries) from Apollo 13's lunar surface experiments package (ALSEP) also reentered Earth's atmosphere along with the spent lunar module Aquarius over the South Pacific and burned up, but the RTG's were designed to survive a launch accident intact, and are believed to have survived reentry and impacted the deep ocean off New Zealand and sank to the bottom where they're safely entombed by the extremely deep ocean. Later! OL J R :)

[@j.mangum7652]

Is nuclear propulsion testing disallowed by anything stipulated in the Nuclear Testban Treaty or other accords agreed apon? The only problem I see is getting the engine in orbit safely.

[@caav56]

Only the Orion-type propulsion (nuclear pulse engine, which uses small shaped-blast nuclear bombs as a "fuel").

[@ubentu]

I would have used a heavier element as a propulisve force and tank capacity, but the statement "the nuclear rocket was found to be feasible." is amazing. 6:42

[@zapfanzapfan]

Heavier element means lower Isp.

[@Live.Vibe.Lasers]

all those fission products..all over the desert, in the air. I'm all for this, but with fission only in deep space (i.e. higher than LEO). This would be irresponsible today, but I suppose standards were different then.

[@caav56]

To be fair, with TWR of current-day NTRs, it's of not much sense to fire them in atmo anyway. Vacuum is where their high ISP can truly shine.

[@iosifconta8112]

super

[@brianw612]

A Radio Isotope Thermo Electric Generator (RTG) is one thing. No moving parts with hardened Uranium pellet containment to produce Electricity. A nuclear engine is an entirely different matter. Very dangerous and fatal if blown up in the Earths biosphere. Very bad idea for a earth launched rocket. We would need to hard contain the fuel at launch, then fuel the vehicle outside the biosphere.

[@NameNotAlreadyTaken2]

A nuclear thermal rocket is not dangerous if the rocket blows up in the atmosphere (i.e. while one of the lower stages is still firing) because the reactor has not fired yet and so is not radioactive. There was never any danger, which is why no one was ever concerned about what you're guessing at.

[@alfaradiation]

NameNotAlreadyTaken2 Everyone is concerned about nuclear fallout, but a big portion of the engine is made out of beryllium, a metal not that friendly to humans.

[@Nifelheim1983]

I hope some day a human can land on the moon like the movei filmed in 1969.

[@mjptrapster]

Who let a child loose with a recorder?!

[@lukestrawwalker]

Yeah that beginning music was pretty confused and awful... OL J R :)

[@bulgingbattery2050]

Theoretically, a spacecraft using nuclear propulsion would keep accelerating until it eventually reaches the speed of light.

[@josele844]

...or runs out of propellant or nuclear fuel. Doubtfully.

[@lukestrawwalker]

No... the closer you get to the speed of light, the harder it becomes to accelerate, as your mass approaches infinity and thus is harder to accelerate. NOTHING can approach the speed of light beyond atomic particles... The best I've seen is plans using a nuclear engine and a MASSIVE supply of fuel is to accelerate to perhaps 10-16% the speed of light, accelerating steadily for over a year's time or more... then of course you have to DECELERATE by burning the engine in the OPPOSITE DIRECTION for the same amount of time... Later! OL J R :)

[@johngardiner2178]

I was not clear in my last post i should have stated if the reactor shielding was cracked and mixed with the propellant gas! they did purposely explode one of these engines to conducted a controlled shutdown, in that respect namenotalreadytaken2 was correct under normal operational procedures it would not produced radioactive exhaust,

[@AuntAlnico4]

This is great, just like the CGI images they show us today !?

[@danischeel4846]

What happened to it?

[@larrybliss8330]

After several attempts to reduce funding, the Nixon Administration canceled it in 1973, although research into the concept continues. (The Administration also cut three Apollo missions).

[@richards779]

Werner von braun must have had lots of sleepless nights fearing the nuclear engine and not his would be the first to reach the moon.

[@AaronGilliland]

Richard S ??? Pretty sure he didn't.

[@lukestrawwalker]

Not really... he knew it wouldn't be ready in time. Heck his own "NOVA" rocket proposal wouldn't be ready in time, which is why he backed at first "EOR" (Earth Orbit Rendezvous) using two Saturn V's, until a NASA scientist named John Houbolt proposed "LOR" (Lunar Orbit Rendezvous) capable of using a single Saturn V rocket with a small expendable lunar lander, the LM. Prior to that, the Apollo itself was going to land on the Moon. Not carrying the large, heavy weight of the capsule and parachutes and heat shield and all the other stuff you needed to return to Earth but didn't need on the surface of the Moon down TO the surface of the Moon made the whole thing possible... IF you used a lightweight lunar lander instead of landing the heavy Apollo on the Moon... Later! OL J R :)

[@mzh3000]

But if the control rods cease up? oops. Better question is, how many nuclear subs never made it back?

[@lukestrawwalker]

Completely different reactor design in subs and ships (Pressurized Water Reactors-- PWR's). I read a declassified NASA report on the risks associated with a nuclear rocket engine launch mishap and there was a danger, but not specifically from the "control rods seizing up" or whatever... some of the Kiwi's shed parts of their reactor cores out of the nozzles but they corrected that problem, and as the engines were only to be fired after achieving orbit to depart on lunar/interplanetary trajectories requiring they exceed Earth's escape velocity, the risks from any of that was really about nil. The main risk was, the engines were inherently close to being "critical mass" and were perfectly safe when DRY because air is a lousy neutron moderator, so they stay safely "subcritical"... BUT if the launch vehicle exploded and dropped the nuclear engine into the ocean INTACT, it would of course flood with seawater on impact and water is an EXCELLENT neutron moderator, so basically it would cause the reactor to go "critical mass" and cause what's called an "excursion" of the reactor... What happens is, the water flooding into the reactor slows the neutrons and allows them to be much more effective at causing fission, thus lowering the effective "critical mass" below that of the reactor core itself in its dry state. So the reactor undergoes uncontrolled fission... it doesn't go off like an atomic bomb, because there's no pressure being exerted on the core to force it to a supercritical state. The unpressurized core simply begins to fission, and as it does so, it rapidly heats up and expands until it reaches a subcritical state where fission stops. In nuclear bomb design parlance this is called a "nuclear fizzle" where the core expands to a subcritical mass before sufficient fissioning has occurred to cause a nuclear detonation, but the sudden release of uncontrolled fission can still produce substantial amounts of heat and radiation, depending on the "excursion" (fizzle) size up to several tons or tens of tons of TNT equivalent explosive power. The criticality of a NERVA engine dropped in seawater would cause a steam explosion, due to the sudden heating of the seawater that had entered the reactor and caused the excursion could not be released fast enough, but not a very large "tons of TNT" explosion... more like a couple hundred pounds of TNT equivalent from their calculations. The problem was it WOULD release fission by-products and spew the contents of the reactor over a fairly large area. Now if the NERVA engine crashed several hundred miles out to sea in 2 mile deep open ocean after a failed booster rocket exploded, the excursion would take place sufficiently far from land to basically be a non-event-- the scattered remnants of the engine's reactor assembly would safely sink into the miles-deep ocean and be entombed on the seafloor. BUT, if a launch pad booster failure occurred and the rocket blew up on the pad or just after liftoff, it's possible that the NERVA engine could be dropped into near-shore waters right off the beach, and the subsequent steam explosion from the excursion would scatter radioactive debris over a fairly large area, and heavily contaminated steam and possibly radioactive isotopes of exposed materials (like in the seawater or structure) could be wind-borne and blow inland and contaminate surrounding areas. The risk of this was much lower if the NERVA engine fell into the sea far from land, as you might imagine. The contamination potential was such that they might have to conduct some fairly decent-size evacuations in the area surrounding Cape Canaveral/KSC if the weather was blowing the wrong way and the engine crashed into near-shore waters or right on the beach... Later! OL J R :)

[@macjonte]

Well that's nice, noo thought about who's going to clean up the jettisoned nuclear waste. Good thing the us didn't go out to space after apollo missions.

[@lukestrawwalker]

Space is REALLY REALLY big... so long as the thing is placed into a safe solar disposal orbit that will keep it far enough away from Earth that it is virtually guaranteed never to reenter (for several thousand years anyway) there's really no problem. Later! OL J R :)

[@concernedcitizen8665]

Google Maps is fun.

[@Chainspike101]

Wonder what the flaw was that kept them from taking off.. Pun intended haha

[@lukestrawwalker]

Politics and money... OL J R :)

[@mtlreiner]

The voiceover sounds like Dick Tufeld (robot from Lost in Space).

[@stevenpilling5318]

Nuclear rocketry is vital and the technology has been there since 1970. However, the presented scheme for a Mars mission is ludicrous. You're throwing away no less than FIVE atomic thrust modules in order to get a capsule back to Earth. The concept of reusability isn't even on the table! Let's scale that down to the Project Arcturus concept where the second stage of the launch vehicle is the NERVA propulsion module. A single spacecraft with no throwaway, capable of multiple missions via orbital refuelling.

[@wildboar7473]

If They have not advanced this much cheaper lighter technology it is because there is a serious problem overhead, VABs?

[@kemalm9383]

Why don't they test it in real conditions? In a vacuum?

[@TheNavalAviator]

17:35

[@Draxindustries1]

Instead of all that rocket fuel and liquid oxygen nasa could use a nuclear blast to get anything into orbit then use a nuclear motor thereafter, unlimited energy, enough to get to mars and back..

[@edge_bob]

WOW....slow down HOW???? Pushing against what to slow down.

[@kylesenior]

Might i suggest you read up on how rockets work?

[@_ShaDynasty]

Edge Bob reversing the thrust?

[@wilsjane]

All modern aircraft have bolt on engines and many people agree that a nuclear engine is on the horizon. A few years ago, a plane taking off from London, landed in the US 18 minutes later. In order to achieve this, it flew at more than 60,000 feet in order not to burn out due to air friction. The problem was, that it is impossible to reach this altitude on a maximum payload of fuel, so the tests were carried out by lifting the aircraft with a space vehicle and releasing it at about 75,000 feet. Their are few details of this top secret flight, but I cannot believe that it was all done unless engines capable of powering such aircraft are somewhere on the horizon. Nuclear fusion power is without doubt a possibility, if we can ever perfect this radiation free alternative to fission.

[@patman0250]

I don't get it why didn't they just use hydrogen oxygen mix that would of made the thrust so much more powerful

[@johngardiner2178]

oxygen is a heavier element , needing more energy to push it through the reactor , creating a slower exit velocity and taking more energy to heat, also they were using hydrogen in a liquid form to cool the engine down its self storing of liquid hydrogen is also lighter then a oxygen hydrogen mix as would require a different storage tank as they have different chemical properties .

[@jeffsasuage3264]

patman0250 yeah an amazing new propelent option just think about it.... We'll call it H2O super efficient and safe to drink

[@kasel1979krettnach]

I think his point is to combine chemical and nuclear thrust by sending H2 and O2 first though the reactor and then burning them in the nozzle. I guess the nozzle wont stand the heat, but I like the idea.

[@richardhorne4963]

Lol it said we closer than ever to a mars mission what was this the 50s and were still ever closer to that mars mission

[@burroaks7]

elon musk has nothing on this

[@TheVergile]

elon musk is building the only rocket so far that would even be able to deploy an upper stage with an atomic engine. Atomic engines are not as useful as you might think. They don't have the Thrust to weight ratio to work as lower stages or boosters. Besides: do you really want radioactive debris raining down whenever you have a launch failure? So lets look at upper stages uses for this design: it has a very high efficiency, which is good. But so do Ion engines. And they are far more reliable. If at any point a number of control rods in your atomic engine fail you are looking at a meltdown (and this has happened again and again both in these atomic rocket tests and other reactor designs). Technology that transports humans should fail s a f e. Plus: once you are in space one of the biggest problems is actually getting rid of heat, so not only are you lugging an extremely heavy reactor to orbit (and it has to be heavy by definition, since Uranium has such high mass), you also need enormous heat radiators. So the only real benefit I see of this technology is for missions to the outer solar system, where the sunlight is too weak for solar arrays to work at acceptable efficiency. So the technology looks nice on paper, but the drawbacks in terms of weight, safety and complexity are just not worth it. Gotta hold out until we have fusion reactors portable enough to get to orbit. No radioactive components, fuel is abundant everywhere in the solar system and energy output is greater by orders of magnitude.

[@themightygareth]

What happens to the spend nuclear reactor that they left orbiting the earth at the end of the mission? They just left it there and said no more. It will re-enter the atmosphere and burn up into cloud of nuclear ash that will be spread over the surface of the planet I imagine. Nice.

[@caav56]

If the reactor is left at the graveyard orbit, it will stay here for thousands of years.

[@simian_essence]

What is needed is a system of safely cocooning the nuclear fuel to protect it from dispersion until after a chemical carrier rocket has put the nuclear engine and its payload into an escape trajectory from Earth (including escape from any "graveyard" orbit). Then the fuel can be taken out of its cocoon and loaded into the nuclear engine reactor, afterwhich the nuclear engine can be started without danger to the earth. As far as ion propulsion goes, an engine of that type should be married to a nuclear thermal engine. They would complement each other quite well on a trip to say, Sedna.@@caav56

[@caav56]

@@simian_essence Maybe. I'm all for reprocessing, though. I guess it won't hurt to have a nuclear fuel reprocessing station somewhere, to maximize the efficiency.

[@omranyousef1277]

If the that capsule was the first landing moment captured in a video, so when did the camera man got there and hocked his equipment to capture the landing. Enough of lies Nasa and show us some real videos and not fake ones. And enough of sgi images

[@leejamestheliar2085]

We are going to the moon, in 2024 ,well maybe not. NASA just announced a new problem that will set the program back again!!!!!!!

[@Live.Vibe.Lasers]

which problem? budget overruns? exploding nozzles? obsolescence? corruption?

[@leejamestheliar2085]

@@Live.Vibe.Lasers 🤔✔

[@Cartoonman154]

Artemis test flight. 16/11/22

[@pasoundman]

75,000 lbs of thrust is actually rather poor !

[@jamescottrell7147]

Yes but it dose not matter if it is not on the lifting stage because it can build up speed over time.

[@pasoundman]

@@jamescottrell7147 How exactly is it proposed to get 100s of tons of rocket + propellant into orbit ?

[@jamescottrell7147]

Use Chemical Rockets. (Back in the day they were going to put the propellant tanks in the space shuttle.)

[@lukestrawwalker]

@@pasoundman It's only to be used on the third stage or planetary escape stages... NOT for ascent propulsion from the surface of Earth, through the atmosphere, and into space itself. It's for LEAVING Earth ORBIT and RETURNING to the vicinity of the Earth after you leave the destination, NOT for taking off into space. The rocket equation shows that basically on the first stage of a rocket, THRUST is *THE* biggest factor in launching the rocket. You have to accelerate a VERY heavy fully fueled rocket from a standstill on the launch pad to as fast and high as you can get it with a thrust sufficiently over the loaded weight of the rocket on the launch pad to ensure a safe liftoff and ascent. (usually at least 10%-15% greater than the launch mass of the rocket and payload sitting on the pad fully fueled and ready to go.) For second and subsequent stages, overall thrust becomes LESS important and specific impulse (ISP) becomes MORE important. This is particularly true for third or higher stages. The thrust basically just has to be high enough to minimize gravity losses on ascent, and the higher the ISP, the better. For third stages or in-space propulsion stages, ISP is the MOST important factor, and thrust is much less important. You still need sufficient thrust to overcome the inertia of the mass of the rocket and accelerate it at an acceptable rate (accelerate it in an acceptable amount of time, thus why using super-efficient but extremely LOW THRUST ion thrusters is basically useless for manned vehicles-- you don't have MONTHS to build up the necessary acceleration due to the extremely low-power engine, no matter how efficient it is!) Thus a 75,000 lbs thrust nuclear engine would be sufficient for an Apollo-mass vehicle to the Moon, although it would burn for probably closer to an hour than the roughly 6 minutes the 200,000 lbs thrust J-2 hydrogen/oxygen chemical engine burned on the S-IVB upper stage to propel the Apollo stack to the Moon... Lower rate of acceleration, but for a longer period of time. An ion thruster would have to burn for MONTHS to provide similar acceleration. Now, if you increase the spacecraft mass, say building a huge spacecraft to go to Mars and land there, well, 70,000 lbs of thrust wouldn't be enough, which is why they were designing the NERVA engines to be clustered or parallel staged into a 3-engine stage... that would be 210,000 lbs of thrust which would be plenty for even a massive Mars-bound stack of spacecraft, hab, lander, and fueled propulsion stages to carry the mission off... Later! OL J R :)

[@pnachtwey]

I would not like to be aboard a space craft that had to dock with a nuclear powered rocket. I doubt the nuke rocket would have much shielding and would be dangerous. The rocket would need to be maneuvered such that the shielding as always pointed the right direction. Nuclear submarines have very good shielding fore and aft. The water around the sides protects those to the side if they are far enough away. In space there is no water for shielding and shield weighs a lot. Also, when the nuke rocket was shut down there is still decay heat. How do they get ride of decay heat in space?

[@lukestrawwalker]

Hydrogen is a good shielding material... plus distance so you build a longer, thinner stage rather than a shorter, fatter one. Shielding isn't as big a problem as you would think it is. If you're docking, you come in from the FRONT of the stage, OPPOSITE the engine, since that's where you'll be connected up to it for the trip. If the reactor hasn't been fired up yet (which it wouldn't on the trip OUT) it is "cold" and isn't emitting radioactivity anyway. Even in the case of the "nuclear shuttle" proposals which would have had multiple reuse nuclear stage trips to/from the Moon with refueling by shuttles, they had plans to handle them safely via "prox ops" (proximity operations) designed to stay certain distances away to provide safety (via the "inverse square" law that governs radiation intensity at a distance) and approaching and docking to the stage or spacecraft attached to it from a specific vector or approach pathway shielded by the tank and radiation shielding built into the stage above the engine or below the spacecraft or both, staying in the "shadow" of the shield from the "hot" reactor... I mean hell even when I worked at the nuke plant, we had "plans" of each room in proximity to the pressure vessel of the reactor, with work times and exposure limits for each area of the room, depending on how much radiation was 'shining through the walls' from the amount of shielding between that particular room or part of the room and the reactor vessel itself... one part of a room might be 'less hot' than another part because there was a large piece of equipment or a water pipe or something that blocked part of the radiation in that area of the room, while other areas might be "hotter" that the rest because that equipment wasn't shielding that part of the room... If they can map it out in a reactor, they can certainly calculate safe distances and radiation flux readings and safe approaches and exposure rates from various distances and angles from a known source of radiation like a hot NERVA reactor... As for decay heat, well, when this was made, it was for a single-use firing, so I figure they were planning to fire the engine til the fuel was almost gone, then shut down the reactor/engine and jettison the stage... do a slight "separation burn" with the payload spacecraft's chemical maneuvering engine to create some distance between it. The remaining hydrogen in the tank would probably be vented through the engine core to help get rid of some of the residual heat in the core from radioactive decay, but that wouldn't last over a couple hours or so I guess... at that point, it's like "WHO CARES??" There'd be miles and miles (maybe hundreds of miles) of distance between the spacecraft and the spent stage after it was jettisoned (depending on the magnitude of the separation burn of the spacecraft engine) and so you could safely watch the glowing engine melt down in the distance til you couldn't see it anymore... Who cares if it melted down after you were far away from it?? It's all weightless and coasting, so not like it's going anywhere... just melt down into a blob of molten uranium and crap and eventually resolidify... be radioactive as h3ll for a LONG time but in solar orbit in a gazillion billion cubic miles of empty space... who cares?? If you're really interested, I'm sure if you looked up the proposals for the "nuclear shuttle", which was a successor to the original NERVA engines and expendable in-space propulsion stages shown here, I'm sure they had some means of dealing with residual cooling of the core after shutdown of the engine, since it'd be absolutely necessary to make the thing reusable... which it was designed to do in the case of the "nuclear shuttle". It was to be basically a nuclear engine powered stage capable of having various payloads or spacecraft dock to the front of it and then it propelling it to the Moon, dropping it off in lunar orbit to either land on the Moon, resupply moon bases, or construct moon space stations or resupply them, or fly crews there and back to Earth... They would dock with the "nuclear shuttle" which would them provide them propulsion to return to Earth, but rather than direct reentry like Apollo did, the nuclear shuttle would retrofire brake itself into Earth orbit, where a shuttle could rendezvous with it to refuel it for another trip, and pick up or drop off a crew or cargo or whatever it was taking back to the Moon... Later! OL J R :)

[@pnachtwey]

@@lukestrawwalker hydrogen in a liquid is good for slowing down neutrons but what about gamma rays?

[@lukestrawwalker]

@@pnachtwey distance and a basic radiation shield, despite the mass, is sufficient for gamma. Later! OL J R :)

[@pnachtwey]

@@lukestrawwalker What radiation shield? A tenth thickness of lead is 2 inches and 4 inches for steel. That is a lot of weight. On top of that, what happens if one must go outside, outside the shield, to fix something?

[@lukestrawwalker]

@@pnachtwey Ok whatever. I know they had the technology, don't know the particulars of the shielding. As for 'going outside to fix something", well, you DON'T... if the thing malfunctions you're not going to fix it anyway. You separate from it and move off to a safe distance if you need to EVA from the spacecraft for repairs on it or whatever. It's not like you're sitting right on top of the reactor, either... the thing is probably 20 meters behind the bottom of the spacecraft, and it's not but about 3-4 feet in diameter-- a thick "manhole cover" just above the reactor will provide quite a bit of shielding, not like the shield has to be right under the capsule 30 feet in diameter and a foot thick or something. I'm sure they worked it out or they'd have never gone that far designing the thing. I don't know a whole lot about the shielding, but obviously they had it figured out sufficiently so it wasn't a "non-starter" problem. Later! OL J R :)

[@simplesimon640]

Putting nuclear material on a rocket is risky. Yes it's better tan chemical rockets but with a failure rate very high during the early day the risk of dispersing radioactive material into the atmosphere would have be disastrous to the human population.

[@MrJm323]

Balony. ...But, because of these irrational fears we have cut the funding for this research and development of nuclear propulsion and power systems; and space exploration has thus suffered. By the way, rtg (radioisotope thermal generator) power systems have flown on many missions - unmanned deep-space exploration missions as well as several of the manned moon missions. (The rtgs of course have radioactive fuel.)

[@kasel1979krettnach]

Uranium-235 is less radioactive than pure natural occurring Uranium ore, before the reactor is started, which happens only once it reaches space... So it is really not an issue.

[@TheVergile]

they did, but since all they were enclosed systems and still incredibly heavy for the amount of energy they created. Unless you plan to have huge (and by huge I mean 100+ crew) spaceships traveling to the outer solar system atomic engines are just not feasible and honestly not worth the risk. The fears are not irrational. By their very definition they are very very rational. You get loads of free energy in space by using solar panels. So unless you go to Jupiter or beyond: why would you carry around heavy uraniums reactor prone to failure? You all seem to forget one important point: higher specific impulse is nice and all - but at the same time you have to give up a huge portion of your payload mass because you need to lug an extremely heavy Chunk of Uranium to earth orbit. And getting stuf to orbit is the expensive part.

[@badreality2]

Yes Uranium is heavy, but think of it this way, if your 2X powerful engine is using 25% of its thrust to lift its core, it still has 50% more expendable thrust, compared to your 1X powerful engine. Is less efficient? Yes. Is it more powerful? Yes. If you have the resources and the shielding, you still go for it.

[@TheVergile]

im pretty sure your atomic engine will NOT be used to launch to orbit. So unless you find a solution to launch into orbit without the use of chemical propellant (and we are -very- far away from being able to do that) the payload economy won't work out like that.

[@willb3698]

JETISON! JETISON ALL THE THINGS!

[@mikewillis44]

heats hydrogen .hardly explains how it works

[@evannibbe9375]

That’s where Scott Manley makes better videos on how to make rocket engines actually work: 1: have a pump to take the liquid from a low pressure tank (1 bar) into the high pressure engine (300 psi). 2: heat the liquid to make it into a gas and pressurize it 3: have the only escape for said gas be an opening directly into space that is just large enough that the gas moves out of it at the speed of sound of a gas of that temperature and pressure 4: have a bell space around the opening such that the gas expands and cools down while always bouncing away in the opposite direction of where you want to go. 5: Newton’s 3rd law of motion makes you go the opposite direction of where the engine points.

[@lukestrawwalker]

@@evannibbe9375 Oversimplified but basically yeah. OL J R :)

[@forcereals731]

No thrust in a vacum...hello

[@jamescottrell7147]

yes and no. Nuclear thermal rocket engines work by shooting gas out the back rapidly. This works in a vacuum. Chemical rockets need oxygen to burn .Space has no oxygen so they bring oxygen in the fuel. This allows Chemical rockets to work in space.

[@southwestxnorthwest]

Man the music in these vintage documentaries sucked

[@southwestxnorthwest]

When I was in Army basic back in 1996 in Missouri, all of the videos we had to watch for classroom training were from the 80s. Man the music was so gay and the budget for these was obviously less than a kid's weekly allowance.

[@videolabguy8624]

The music gave me an impending sense of doom! Plus, you can't dance to it.

[@tobylangdale95]

Tim Nelson , hell yes! Back in the day we hated that onerous music about as much as the narrators awful monotone voice, been a long while, I nearly puked!

[@southwestxnorthwest]

That made me laugh. Only someone in basic would appreciate that comment. I remember sitting there in class, sleepy as hell and trying not to fall asleep cause you know the drills would take us all outside and smoke our asses.

[@aliensoup2420]

I think its a product of the impressionistic modern art craze in the 60"s. You even heard it in the musical score for the original "Planet of the Apes".

[@M12Howitzer]

Now you can imagine how ridiculous would Musk's BS videos about Mars 'colonization' would look like in 50 years )))

[@RaimoJackson]

That power can never use on earth because of the radiation of the exhaust gases

[@NameNotAlreadyTaken2]

There's no radioactive elements in the exhaust gases.

[@RaimoJackson]

How can it be?

[@NameNotAlreadyTaken2]

I explained it in another comment I made here today. Hydrogen's nucleus is just 1 proton. If it catches a neutron it becomes deuterium - stable, naturally-occurring, and non-toxic. Assuming a tiny bit of tritium is produced, it's still not a big deal because it's such a trace amount. The fuel channels in the reactor are lined with a super hard ceramic that prevents uranium or fission products from escaping (this was in the video). The engine and the concept of use (for deep space missions) is incredibly safe, albeit incredibly expensive due to all the thrown-away hardware involved. The only danger is to the budget, if these NERVA engines were used for bigger, more ambitious NASA manned missions to outer space. It's always about money, and in the case of NERVA, it was really blatantly about money.

[@Ar-kx4hp]

NameNotAlreadyTaken2 yes and no. While the engine is firing at full thrust you are correct. Of course outer space is exceedingly radioactive so out there it's a mute point. But at the build up to firing or wind down phase inside the atmosphere you have a red hot nuclear core directly exposed to atmosphere at a substantial level of pressure. Much more complex atoms and molecules than hydrogen will be pushed down the exhaust and be exposed to that core before heat causes them to rise again. That's without even thinking of air born dust. They had to move the spent engines by remote control remember. At this stage this thing is a miniaturised Chernobyl. I wouldn't want to breathe the air within ten miles of it.

[@lucasbowering]

This is really cool I am a big fan of NTP but I did think they were as clean as you are saying. Do you think it is possible to develop a single stage to orbit nuclear thermal rocket? Even if it did release a small amount of radiation people could be shielded and launches could occur from a remote island. This is much safer than a nuclear bomb test many of which have occurred on the mainland of the US. Once SpaceX gets to Mars their first priority will be to develop nuclear power/propulsion away from the prying eyes of people on Earth.

[@leejamestheliar2085]

You have to think about it, most of this was done with slide rules. We have had super computers for decades and we still haven't been able to go to the moon or Mars. Someone is not telling you the truth about.......anything!

[@almostfm]

Supercomputers are great, but they're not actually what gets us to the Moon and Mars. That takes big-ass rockets, and big-ass equipment to build and launch them. _None_ of that is cheap, and successive presidents and Congresses have decided they don''t want to spend the money on it. I know it's not as sexy as "Ohhhh, it's all part of 'the conspiracy'!", but it has the advantage of being true.

Pretty boring vid but the music is great.

[@xiniks]

Seán O'Nilbud pretty great vid but the music is boring.

[@neilufe]

My idea 6years ago

[@99rm25099]

crazy BS

[@oberguga]

/watch?v=Um-RhIy5I64 russian analog.

[@jgaworski1]

he said jackass

[@lukestrawwalker]

Yep like "male donkey"... LOL:) OL J R :)