What a wonderful incredibly detailed reel of celluloid. There must have had some realistic concerns of an excess of neutrons ionizing with the atmosphere, certainly enough to have environmental doubts about the reactors efficacy - a veritably invaluable resource, however, of technical and scientific information for the serious nuclear enthusiast to ponder.
This all happened while I was in high school! What were the radioactivity levels of the propellant gases during operation? Was that a factor in why the NERVA rocket was never used?
Little to no radiation in the exhaust. These were called closed loop engines and the fuel was solid. So the propellant/coolant is just normal hot gas. As for why they were never used. It was planned to use them for the Apollo missions. But it was quickly discovered that while extremely promising they couldn't be made flight ready before Kennedy's end of the decade deadline; so they were shelved in favor of the conventional Saturn V that had a more optimistic build schedule. The idea of nuclear rockets has been revisited many times. But without the Apollo Era big space funding it's just a curiosity. An extremely frustrating curiosity for space nerds since they're drastically better in every way and we know they're possible.
@@bronzedivision I pretty well suspected that this was the story. I'm also sure that anti-nuclear political pressure groups had a place in the equation. Whether the propellant mass was liquid hydrogen or plain distilled water, there is little there to become irradiated and nothing long term. This means that NERVA could be used to lift a spacecraft directly off the earth's surface and on to an interplanetary objective. Of course, writers were predicting that since Fermi's first reactor! I'm still amazed that this was not done during the 20th Century. How much simpler a way of delivering payloads through space directly, point to point. With the Moon as a refueling stop, the entire inner system would be economically accessible. I had really hoped to see that in my lifetime. I'm often reminded that the first movie to deal with it ("Destination Moon" of 1950) was made a year before I was born. The time we've wasted!
@@stevenpilling5318 "Specific Impulse" is a good way to compare rockets, although there are many others and it gets technical. It's why we use 'rocket science' as a idiom for difficult. :P Anyhow; conventional rocket have SI of 350-450 at best. With around 800 being the best imagined if metallic hydrogen is ever invented and made practical. Each of which is an all but impossible goal. And for reference 300 SI is the (very) appropriate minimum to be useful. The small gap between these two numbers of only 50-150 SI is the reason why rocket payloads are so tiny; typical just a few percentage points of the total mass. But SI is a nonlinear metric and small improvements can net huge gains. Whereas the specific impulse of the bottom tier nuclear rockets tested in the 60's and again for a bit in the 80's was around 850-900+ and far FAR better nuclear rockets are possible. But 900 is what we've prototypes for certainly and directly measured with the thing blazing away on a test stand. With 900 specific impulse it's theoretically possible to build a rocket that's HALF payload. Although really expect a random grab bag of inefficiencies to eat up a little of that. And nuclear rockets are inherently reusable, which isn't needed but is a popular idea these days. That would mean rather than 40-50+ Space Shuttle missions a nuclear rocket of similar size to the Saturn V could build the International Space Station in about 3-5 trips. ;)
@@bronzedivision I've seen recent videos on the subject that describe the nuclear thermal rocket as having twice the SI of the best chemical propulsion. That, however, was based on the static tests of the early Seventies. I'd bet that they could do a lot better today.
Although the specific impulse of this type reactor/propellant can be very high, just look at the exhaust plume of the nozzle in this and similar videos. There is virtually NO thrust. There isn't a hint of a shock diamond. Based on the visual flow stream, I'm guessing that the nozzle exhaust pressure might be at about 100-to-200-psi, as based on steam venting comparisons. Using Water as the propellant would raise the total thrust by a decade or more, and the volume of the tankage would be reduced by a factor of 100-less or more, and not require as much insulation. The reduced SI would be well offset by the weight loss and size reduction of the actual rocket.
Spewing out radation products at a prodigious rate what could go wrong jeeeezzzzzz brilliant ! Additionally i particlarly like the common automotive hose clamps on the fuel feed pipes ( why did the reactor explode sir ) well those pep boys hose clamps ain't worth a dam sir ! Weeeeeee!
@@mathewferstl7042 Yep, the reactor is the heat source, the only thing chucked out the nozzle is hydrogen. In theory. Actually testing these things would be more risky than using them if it melted down, THEN you could have a spewing radiation situation. Obvs these were designed for use in space only, the actual thrust on these engines is pretty poor and weight very high, but very high impulse, so perfect for vacuum operations. Chemical rockets are the only way to orbit for the forseeable future.
@@Joe_VanCleave Neutron bombardment of ordinary hydrogen does not produce tritium. However, if you swapped out some (or all) of the hydrogen for deuterium, then you would get tritium. This happens in some nuclear reactor designs, the most well known of which is the Canadian "CANDU" civilian power reactors: These are pressurised water reactors which use heavy water (aka deuterium oxide) as their primary coolant. The neutron flux in the reactor core converts some of the deuterium into tritium. This is actually a significant source of commercially available tritium, since it can be extracted and purified from the reactor coolant. Anyway, the nuclear thermal rocket reactors would almost certainly be capable of producing tritium if you fed enough deuterium through the core during operation. I don't know that this would be a particularly useful or practical way of making tritium though, because you would have to extract it from the rocket exhaust somehow, and that wouldn't exactly be easy to do.
What a wonderful incredibly detailed reel of celluloid. There must have had some realistic concerns of an excess of neutrons ionizing with the atmosphere, certainly enough to have environmental doubts about the reactors efficacy - a veritably invaluable resource, however, of technical and scientific information for the serious nuclear enthusiast to ponder.
I think this video is about to take off.
Like to see the analyais video of them taking it apart
This all happened while I was in high school! What were the radioactivity levels of the propellant gases during operation? Was that a factor in why the NERVA rocket was never used?
Little to no radiation in the exhaust. These were called closed loop engines and the fuel was solid. So the propellant/coolant is just normal hot gas.
As for why they were never used. It was planned to use them for the Apollo missions. But it was quickly discovered that while extremely promising they couldn't be made flight ready before Kennedy's end of the decade deadline; so they were shelved in favor of the conventional Saturn V that had a more optimistic build schedule. The idea of nuclear rockets has been revisited many times. But without the Apollo Era big space funding it's just a curiosity. An extremely frustrating curiosity for space nerds since they're drastically better in every way and we know they're possible.
@@bronzedivision I pretty well suspected that this was the story. I'm also sure that anti-nuclear political pressure groups had a place in the equation. Whether the propellant mass was liquid hydrogen or plain distilled water, there is little there to become irradiated and nothing long term. This means that NERVA could be used to lift a spacecraft directly off the earth's surface and on to an interplanetary objective. Of course, writers were predicting that since Fermi's first reactor! I'm still amazed that this was not done during the 20th Century. How much simpler a way of delivering payloads through space directly, point to point. With the Moon as a refueling stop, the entire inner system would be economically accessible. I had really hoped to see that in my lifetime. I'm often reminded that the first movie to deal with it ("Destination Moon" of 1950) was made a year before I was born. The time we've wasted!
@@stevenpilling5318 "Specific Impulse" is a good way to compare rockets, although there are many others and it gets technical. It's why we use 'rocket science' as a idiom for difficult. :P
Anyhow; conventional rocket have SI of 350-450 at best. With around 800 being the best imagined if metallic hydrogen is ever invented and made practical. Each of which is an all but impossible goal. And for reference 300 SI is the (very) appropriate minimum to be useful.
The small gap between these two numbers of only 50-150 SI is the reason why rocket payloads are so tiny; typical just a few percentage points of the total mass. But SI is a nonlinear metric and small improvements can net huge gains.
Whereas the specific impulse of the bottom tier nuclear rockets tested in the 60's and again for a bit in the 80's was around 850-900+ and far FAR better nuclear rockets are possible. But 900 is what we've prototypes for certainly and directly measured with the thing blazing away on a test stand.
With 900 specific impulse it's theoretically possible to build a rocket that's HALF payload. Although really expect a random grab bag of inefficiencies to eat up a little of that. And nuclear rockets are inherently reusable, which isn't needed but is a popular idea these days.
That would mean rather than 40-50+ Space Shuttle missions a nuclear rocket of similar size to the Saturn V could build the International Space Station in about 3-5 trips. ;)
@@bronzedivision I've seen recent videos on the subject that describe the nuclear thermal rocket as having twice the SI of the best chemical propulsion. That, however, was based on the static tests of the early Seventies. I'd bet that they could do a lot better today.
You are a great artist.
Although the specific impulse of this type reactor/propellant can be very high, just look at the exhaust plume of the nozzle in this and similar videos. There is virtually NO thrust. There isn't a hint of a shock diamond. Based on the visual flow stream, I'm guessing that the nozzle exhaust pressure might be at about 100-to-200-psi, as based on steam venting comparisons. Using Water as the propellant would raise the total thrust by a decade or more, and the volume of the tankage would be reduced by a factor of 100-less or more, and not require as much insulation. The reduced SI would be well offset by the weight loss and size reduction of the actual rocket.
For SSTO, HOTOL seems superior to this and lower risk. But this technology surely has advantages in space.
Spewing out radation products at a prodigious rate what could go wrong jeeeezzzzzz brilliant ! Additionally i particlarly like the common automotive hose clamps on the fuel feed pipes ( why did the reactor explode sir ) well those pep boys hose clamps ain't worth a dam sir ! Weeeeeee!
there were no radioactive products in the exhaust. it was a closed loop engine. do you're research
@@mathewferstl7042 Yep, the reactor is the heat source, the only thing chucked out the nozzle is hydrogen. In theory. Actually testing these things would be more risky than using them if it melted down, THEN you could have a spewing radiation situation. Obvs these were designed for use in space only, the actual thrust on these engines is pretty poor and weight very high, but very high impulse, so perfect for vacuum operations. Chemical rockets are the only way to orbit for the forseeable future.
@@mathewferstl7042 I’m curious as to the neutron spectrum from the reactor and if tritium would be bred from the hydrogen in the exhaust product.
@@Joe_VanCleave Neutron bombardment of ordinary hydrogen does not produce tritium. However, if you swapped out some (or all) of the hydrogen for deuterium, then you would get tritium. This happens in some nuclear reactor designs, the most well known of which is the Canadian "CANDU" civilian power reactors: These are pressurised water reactors which use heavy water (aka deuterium oxide) as their primary coolant. The neutron flux in the reactor core converts some of the deuterium into tritium. This is actually a significant source of commercially available tritium, since it can be extracted and purified from the reactor coolant.
Anyway, the nuclear thermal rocket reactors would almost certainly be capable of producing tritium if you fed enough deuterium through the core during operation. I don't know that this would be a particularly useful or practical way of making tritium though, because you would have to extract it from the rocket exhaust somehow, and that wouldn't exactly be easy to do.