Nuclear rocket engines | Lex Fridman Podcast Clips
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- เผยแพร่เมื่อ 5 ก.พ. 2023
- Lex Fridman Podcast full episode: • Tim Dodd: SpaceX, Star...
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Tim Dodd is host of the Everyday Astronaut TH-cam channel, where he teaches about rocket engines and all things space travel.
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Full podcast episode: th-cam.com/video/5eK5A_43pkE/w-d-xo.html
Lex Fridman podcast channel: th-cam.com/users/lexfridman
Guest bio: Tim Dodd is host of the Everyday Astronaut TH-cam channel, where he teaches about rocket engines and all things space travel.
My friend, now deceased, Al Poindexter was a dedicated engineer on project NERVA. He told me about how he was so dedicated to the mission that he stayed with engine from the moment it was loaded on to a train car at Westinghouse Astro Nuclear until it arrived at Jackass Flats and then throughout it's testing. Literally he stayed on the train car with it! He also told me that the engine was protected and packed off to Hanford, Wa where it sits and was still in operating condition at that time..
"The Mars mission became NERVA's downfall. Members of Congress in both political parties judged that a manned mission to Mars would be a tacit commitment for the United States to decades more of the expensive Space Race. Manned Mars missions were enabled by nuclear rockets; therefore, if NERVA could be discontinued the Space Race might wind down and the budget would be saved."
Saved $1 today to spend $10 tomorrow
Okay CEO of space
@@Arizona9001 but its not wrong though,
Just remember congress doesn’t spend money. It takes your money and devalues it by diluting the supply of money for it’s own mostly useless projects.
Hey this was all great. Do another interview with this chap.
This is an exciting topic to me because I remember reading about Project Orion in Omni Magazine in 198...6? It seemed so cool to lil me. Thank you for the amazing covo!
Pulsed nuclear thermal is an interesting expansion of regular nuclear thermal engines. Using pulsed reaction (inserting/removing control rods) heats up propelant to higher temperatures giving higher specific impulse.
Nuclear Pulse also known as Project Orion. It is a pretty cool concept.
Project Orion isn’t a nuclear pulse engine, it is literally pulsed nuclear weapon detonations to propel the craft.
you waste most of the energy you create. must be a better way to do it.
I often think about if the moon were rich in some scarce resource, would we be way further advanced in our space travel capabilities? It’s such a shame that we really haven’t progressed a timer further from the 60s.
bien joué, Bravo LEX
I love you guys. Tim misspoke, the reactor is fission, not fusion (high mass nucleons decaying, not light mass fusing). I am sure it was just a misspeak. I have always said nucular, not nuclear, power. built a few in my career.
Nice, where was this though? I thought no one had built new reactors since the seventies.
@@muhammadschuitema1443 Plenty of nuclear reactors are still being built, particularly in Asia. According to the World Nuclear Association's reactor database website, there are 58 new reactors currently under construction, totalling about 60,000 MWe. Hell, there are already three new ones online just this year. Nuclear still has a bright future.
Other than the obvious weight problem, hydrogen is not easy to deal with. It is difficult to build tanks to hold it in, as the tanks will usually leak because hydrogen molecules are very small. Plus, the tanks become very heavy and nitrogen doesn't have / give a good amount of thrust. I believe hydrogen should be off the table for use until we can find a lighter weight tank solution.
Hydrogen powered Delta IV/ Delta IV Heavy, which are extremely capable vehicles. And in the context of a nuclear engine, you get WAY more thrust, so the thrust of hydrolox engines is not a concern.
@@cerebralm I agree with you about the nuclear configuration, but it's not really worth moving forward until we can create lighter weight tanks that won't leak. Mainly because they need to contain the hydrogen for long periods of time, traveling from Earth to The Moon, Mars etcetera.
@@ShawnRitch Ah, right. Current-gen hydrogen systems need top-ups till just before lift-off. We will have to do better...
@@cerebralm :) consensus ! Thank you
lex has been watching PBS space time
Sometimes 'guessing about things we don't know about', is the best way to come up with new ideas, new thoughts! Your truly thinking outside the box!
The late Stanton Friedman was developing these 50 yrs ago. We have technologies far in advance of rockets. Ben Rich head of the top secret Lockheed Martin Skunk Works admitted at a conference that we have the means to take E.T. home.
You guys missed talking about rotating detonation engines.
But that said, strapping a thousand birds to your head would work.
"it'd be stupid for us to guess about things we dont even know about yet." isnt that literally how science works.
Why not flying ? Because in 1996 NASA dropped a plutonium core in the atmosphere and pretty much covered it up.
Nuclear thermal is basically still the same temperature as chemical rockets because we're limited by materials properties. The only real benefit you're getting is the ejecta are Hydrogen which are 9-18 times lighter than water at the same temperature (and accordingly 3-4 times higher Isp)
Not if you use a gas core. Then your core is uranium plasma.
IMHO a good reason to not go for nuclear rocket engines is that, even if it's just payload and thus not used for take off itself, but only to be started way out of earth's way, you don't want to risk to spread radioactive material over earths surface in case the rocket blows up during take off.
Steam rockets, how Punk!
Do not strap a thousand birds to your head 🚨
Its a real shame the Sea Dragon never came to pass, western leaders didn't want anything to do with the pursuit of space travel so it was a shelved design.
It would have been amazing to see take off.
Just one sort of Thrust/Shockwave propulsion that could be tested in the next few 100 years to see whether it makes any sense to use it, could be something that uses energy from focusing solar energy transmitted by solar panel satellites on space. The energy from several transmitting satellites is focused (some groups like one at Caltech are already working on Solar Power on orbit) onto a LASER on the rocket (modulo taking care of all the precise control of several beams following the rocket motion). If the energy is going to come from outside, energy density is perhaps not a big problem (although energy carrying/handling capacity would be), so might as choose the propellant independent of the energy density. As mentioned in the video, something (propellant) still needs to be ejected until we can control spacetime or quantum fields at scale, and the propellant needs to be stored on the rocket unless it can be harvested during the motion which is rather difficult with the thinning of the atmosphere with increasing altitude. So, let's say compressed air is used as a propellant. The LASER ionizes the air at the exit of the tank, and the ion jet is accelerated with magnetic field on board the rocket. It is likely that some forward boost/shockwave phenomenon could be studied based on certain kinds of elastic behavior of the magnetic field. If solar power could be harvested from space in reasonable quantities, it could potentially be used to power rockets.
They have it, its been around since around the 50s and it works. But its solely for space travel because of its safety regulations. Goes roughly 3/10 the speed of light.
3 mile island put nuclear propulsion on the back burner in the US. I remember all the public outrage when the first nuclear satellite was launched
Wouldn’t the exhaust bombard earth when leaving and arriving
Yea it would. Its an upper stage launched on chemical rocket. The real fear is an explosion on the pad or in the air during liftoff. Basically a dirty bomb.
They would use liquid and solid fuel for leaving and entering earth. Since the chemical propulsion is more efficient in that way.
@@Silverseekr I mean once you are in orbit
@@bar10dr Don't point it at Earth. When a rocket is leaving or arriving at a planet it is pointed tangent to, not directly at, a planet.
@bar10dr bar10dr You would ignite your nuclear thermal engine once out of orbit.
The exhaust isn't really an issue. The reactor heats hydrogen and the hydrogen expands as an exhaust.
Nuclear electric, the same.
1 pulse. Zero resistance.....???
LoL, initially, I thought that you believed that nuclear or fusion drives could allow us to go study black holes.
Anyhow, I really hope one day we'd unlock tech that nowadays is unbelievable. Yet we're at a point in history that requires bright or even superhuman minds. Like thinking about 8 or 11 dimentions. To my understanding, both machine learning and physics make use of those for one reason or another.
Why not just build it in space from pieces?
Would it make any difference? At some point the fuel has to be delivered and that rocket is a dirty bomb if its a Rud.
@@jackdono5673 Not if you get the fissile material from space. You don't build things in space with materials from Earth. That is how you make them expensive.
99% of us are just peasants in physics land. Well I'm in good company!
Element 115 bois
Moscovium ?
I think is all going to be about harnissing vast amounts of energy. Energy seems to be the one constant in all models. Essentially all mass is energy as per relativity, and as mass seems to derive gravitational potential, potentially so does energy. In theory you can bend space-time enough to travel at or over faster than light.... only problem is you need silly amounts of energy, like more than available in our galaxy, to bend space enough to move just a few kg. Hopefully one day someone will break this curernt understanding of physics wide open👍
Thrust is about reaction to momentum of the exhaust so hydrogen being the lightest element is rather lousy.
Lower mass more-than-compensated for by higher velocity potential?
He wears a T-Shirt of Elon's Holy Grail.
Evian BUssin.
Aliens got around it .. by using Mercury electromagnetic drive energy to use a field to push themselves beyond light speed
nuclear rocket engines ok but with people is that not a problem with weight of shielding ?
Not really - the exhaust points down, the people are at the pointy end. Same shielding that protects them from Solar Radiation will protect them from the engine.
@@PiDsPagePrototypes What is a disadvantage of nuclear rocket engines?
Disadvantages of nuclear rocket include radiation effects by the nuclear reactor, and the high weight of the engine assembly.
@@aaronrobertcattell8859 Mass of the engine is offset by the ISP and the size of the payload it can push. Sheilding is a non issue for passengers, as the sheilding for cosmic rays and solar winds will also block onboard reactors.
@@aaronrobertcattell8859The radiation from space is far worse than the reactor. For mars astronauts will get less radiation due to quicker missions.
Clearly we're not fully there design wise
4 us 2 fully understand this 1 has to look at poo
In layman terminology cow crap when heated by the sun shoots tiny pieces of shit to the atmosphere quicker and ultimately faster than anything else on earth
So imagine the rocket is the tiny piece of shit , we're missing the turd
This is not a joke
For the question at 4:20:
E L E M E N T 1 1 5
Moscovium ?
@@PiDsPagePrototypes Yes, not sure which isotope, but supposedly a stable isotope of this element was key to operating an antigravity generator from an alien craft.
It's part of Bob Lazar's story, where he claims to have worked on reverse engineering alien technology in area 51, which to be fair is quite out there.
I thought dark energy was up to like 95% of our universe and we can barely see it, we have nothing if that's stuff plays a big rolein an anything, pessimism at its finest 🖖 but it's true how much can we really see we can barely catch individual pieces of dark energy and if that's 95% it'll tear everything we know to shreds in an instant when we're smarterer some day if we make it that far knock on wood
barely see it ? we can't even detect it...
65% is dark matter. 27% dark energy.
Dark matter doesn't emit. We can't detect it directly, only by the way other objects, like galaxies, behave.
There are other opposing theories, like MOND.
Dark energy could well be the cosmological constant, the slight repulsive nature of empty space. Although the calculations regarding that are orders of magnitude wrong. More to learn.
Bro how are u saying any of this? Lol
2nd
Let me answer the first question right off the bat and the answer is... HA!
Might as well have horses pulling wagons again, because that's how old that technology is!
Anti-gravity, unless its at that level or above, its a waste of time to talk about.
This guy says so much while saying almost nothing
He said we already understand everything. 😂🤣😂😂😂😂😂😂😂😂🤣🤣😂😂😂😂😂😂😂😂😂🤣😂😂😂🤣🤣😂😂😂😂
No, he said that our current models describe how the Universe works extremely accurately, meaning that it will be difficult to find further gaps in our knowledge and nearly impossible to upend our current understandings as they work so very well.
@@filonin2 bhahahahahahahahahahahahahah. Fuck humans are funny.
@@filonin2 We know everything oh yeh except for that pesky dark energy that makes up 68% of the universe. But yeah besides that we know everything. 🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣😂🤣
🫣 He uses fission and fusion interchangeably lol, also nothing he described involves a fusion or fission reactor, would highly recommend that no one listens to this portion of the podcast and does some actual research 👍