Is Thrust-Based Artificial Gravity IMPOSSIBLE!?
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- Опубликовано: 31 май 2024
- Today we're following up on my previous artificial gravity video and talking about creating "gravity" by accelerating with a rocket. Is this even physically possible? We find out through a fundamental engineering analysis using existing technologies to see what humankind can truly do in space exploration.
Intro/outro Music: "Blast" from Bensound.com
(0:00) - Intro
(1:23) - What's the problem?
(4:14) - Can SpaceX do it?
(6:40) - Can Hydrogen do it?
(9:06) - Can Nuclear do it?
(10:38) - Can Electric do it?
(11:57) - How fast are we going?
(12:58) - How long (short) is the trip?
(15:09) - Outro 
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I get the algebra, that a ln(1>) is negative, therefore making delta v negative, but I don't understand what does that mean in reality. A 1> engine still accelerates you, doesn't it?
The ratio is actually initial mass to final mass, if you put in a number less than 1 it implies you gained mass while burning the engine. We’re only using TWR in that equation because we want our intial to final mass ratio to match the initial TWR so you can accelerate at at least 1g
If you can build an engine that’s capable of constant 1G acceleration, then you’re obviously only using a fraction of its true capability most of the time, just to accommodate the humans.
I've always said that the problem with generating continuous thrust for long space journeys isn't carrying enough fuel -- it's carrying enough reaction mass.
If a ginormous aircraft carrier or nuclear submarine can run for years and carry enough food, fuel, and oxygen for the entire trip, why can't a spaceship?
#ItchyFeet
Well, for non electric propulsion the fuel is the reaction mass but I think I see your point
That's insane 🤯
Well that was helpful
Nice timing!
With a lot of antimatter maybe, but with any kind of propulsion we have today, no. And thrusting all the way is just wasteful as if your goal is also to reduce the length of the trip you want to burn as hard as you can at the start and the end because is massively reduces travel time verse burning all the way there and all the way back.
You are easily the most pleasant person I've ever seen. How do you manage that?
Great follow-up video! @9:24 did I hear you say 'nucelar' instead of 'nuclear'?
Yeah, I didn’t catch that until I was almost done editing
One thing you don't really mention is staging. Right, in principle you can jettison your rocket engines and tanks whenever they run out and that will get you higher numbers. Though also ridiculously high vehicle sizes. Since beating the maximum for single stage raptor of 18 km/s of 1 G acceleration is going to require many many stages.
As of this moment, that other video is up to 491 k views!
I hope we can figure out some other "scifi" propulsion soon. Most of our space faring hopes and dreams are not possible with what we have now.
We're barely at "steam engine" level in space travel today.
Even if we could build a warp drive, does that affect inertia within the "spacetime bubble" at all?
We also do not know minimum gravity needed for long term health. But I want to add exercise can reduce bone loss and more. Compression and resistance suits can also reduce negative effects and help reduce bone and muscle loss. Genetic engineering and drugs have been looked at and even diet may effect and help reduce mineral loss muscle and help kidney. I don’t think any of these can 100% replace gravity but maybe we can get away with lower amounts then? Also what about combining linear gravity from accelerating, gravity from accelerating spinning speed, and gravity from spinning ? But that may cause complex balancing act
Now calculate acceleration gravity for a Nuclear Salt Water Rocket. Weapon-grade.
When I read the title, my mind immediately read "Torchship" and Fusion Propulsion. I know it's theoretically possible to have a constant 1g burn for a Brachistochrone Transfer. But I also know that using any drive we could theoretically make short Orion, it is impossible, and nobody wants to revive ol' boom-boom as far as I'm aware. Sure it's wasteful, technically, but also, iirc, a total constant 1g burn on its transfer, including a flip and counterburn, will get you there in just a few days. But... that's a very long ways off.
I don't do equations, so I have to ask some basic questions. I don't understand why you sketched such a tiny crew area and, proportionally, huge fuel tanks. Is the real issue in all of this only the amount of fuel a ship has to carry to have an ongoing acceleration?, Does it make major difference if, instead of matching Earth gravity you only aimed to produce, say, about 1/5th of Earth's gravity?--just enough to give crew a sense of weight to help maintain some kind of muscle viability, and prevent things from just constantly floating around in weightlessness---you know, so you could eat properly and play old-fashioned chess or some such. (Btw, do ships HAVE TO carry all the fuel? Couldn't there be, for instance, a number of remote-operated fuel-supply "ship-tanks" put into some kind of static orientation in space between Earth and part way to Mars ahead of time that a manned, Mars ship could use to re-fuel, gas-station like, along the way?---this to avoid having to transport ALL of the needed fuel within its own hull. (Has anybody proposed re-fueling stations along the way, or is there absolutely zero practical way to do that?)
Would nuclear fueled ships help solve the steady-acceleration-gravity problems?---or are they impractical (and, if so, is this primarily due to safety concerns?)
No matter how much or little acceleration you want, if you're burning your engines constantly (or even for 30 minutes per day or whatever as suggested) you're wasting a shit ton of fuel. If you set up refueling tanks, then you're changing one trip to mars to like a few hundred trips to various points along the path, and you have to make sure they all line up in their orbits at the exact time you're going to pass them so you can refuel. I'm not going to try to imagine how much that would cost or how long it would take to set up. The alternative is not doing any of that because in space you don't need fuel except for starting and stopping, and you strap the astronauts to a spinning wheel for 30 minutes a day, and you put velcro on their chess pieces.
@@ryanmccampbell7 Thanks. I appreciate your taking the time to respond!
I wasn't actually thinking about any more than maybe 3-4 re-fueling stops, (but how would you know since I didn't clarify that/my bad).. I mean, what you are suggesting makes total sense. That is the current state of things. I'm very interested in space exploration, but am not remotely a physicist able to calculate all of the factors. I'm just looking at it from a "what if" and/or "sometime in the far future" perspective, ie as an imaginative exercise (being a film person/writer who grew up at a time when the idea of space travel itself, even only to the moon, was kind of a crazy joke, ie merely a fantasy of the impossible.)
Other than the fuel issue (oh, THAT little ol' pesky factor! ha), the steady acceleration is the most direct, seemingly most elegant way to provide a constant gravity-based/"ground-oriented" life for a crew while traveling through space. The problem seems, in its entirety, to be solely about fuels that we can currently, concoct or even imagine.. (Are there any nuclear-based and/or ion drive type ideas that show promise towards more efficient, less mass-weight based propulsion options? Guess I should just go and look into this myself to satisfy my own curiosity.)
Thanks for your thoughts! (Now if only we could capture one of those ever-elusive tic tacs that seem to have been badgering the naval air force...and slave their tic-tac-tech to our space-traveling needs and desires! ha...)
@@RSEFX I think that while naively it seems like the "acceleration = thrust" can kill two birds with one stone, really trying to repurpose one thing for another just makes it bad at both things. The most efficient way to get a space ship from point A to point B is not going to be constant acceleration. I don't have a good idea of the complications but I imagine the spinning designs (either with a tether, a ring, etc) are much more practical because you don't need to constantly spend energy/mass to produce artificial gravity. It's just free once you get it spinning up.
@@ryanmccampbell7 I just figure the future is a long long time (unless we wipe each other out) and that a killing of multiple birds (which sounds rather mean-spirited) with one stone may be not the worst of goals/may be found, in time, so we will no longer be moving through space in the only ways we can imagine in the here and now. (Maybe it'll take a stone and an extra pebble or two?) But I shouldn't mind being on a carousel again, and I always enjoyed the "Round Up"", that ride that plastered you centrifugally to the wall of a big spinning cylinder. In fact, I always wanted to try to stand up on that wall, sorta as characters did in the old space films that took place in big donuts rotating above the Earth.
Going to the moon was considered a naive fantasy for centuries, right up until my earliest years: Such was the unimaginable thing. That "fool's errand" was proven to be not that after all. Well I guess its that quixotic spirit that often makes us think about challenging windmills, even if and when they spin where there IS no wind.
"Would nuclear fueled ships help solve the steady-acceleration-gravity problems?" -- steady acceleration means gaining the same amount of kinetic energy per unit mass with each metre travelled. If you climb a tall tower on Earth, carrying something heavy, you increase that thing's potential energy by an equal amount with each metre climbed. If you then drop it, it gains that same amount of kinetic energy per metre fallen.
But it falls at an increasing speed. Its rate of gain of kinetic energy, its kinetic *power*, increases. That's constant acceleration for you.
Nuclear fuel lets you pack plenty of energy for interplanetary trips in a small fraction of a ship's mass, but increasing the power, steadily for weeks or months, soon hits a limit. You can't convert nuclear energy to kinetic energy efficiently enough that you aren't saddled with a huge heat problem. Along with kinetic power that you want, you also have thermal power that you have to get rid of. Since this increases at the same inexorable rate, *if* you manage to accelerate steadily, inevitably you can't sustain a full gee for very long.
In short: no. Nuclear energy promises much quicker interplanetary trips, but not as quick as one gee forward boost halfway, then one gee braking the remaining half.
If acceleration is gravity then it means space/time permeates through and applies force to anything with mass. Instead of trying to accelerate through space/time, why not try to make space time flow? Kind of like a water pump shooting water out of a hose. We know how to move through space but imagine we could make space move through us instead. This would open up a whole new world of propulsion and solve the artificial gravity issue.
PLEASE LET ME DO MUSIC FOR YOUR CHANNEL CON YOUR VIDEOS ARE SO COOL
So smart
Your channel is unbelievable! I love it with a passion, and I just discovered it an hour ago!
I hope you'll have a famous career and your name literally, physically etched on a panoply of honor in the O'Neill halo :)
But why do you keep bringing Einstein into this? Not that he would disagree with any of these concepts, but you don't *need* Einstein for any of it. In fact, it's all Galileo here... A little nod to the old man would be nice.
I wonder if the starship could be used to ferry up building materials and fuel up to orbit or the moon in order to build and power a long range ship. Or built a moon base and mine the crap out of Luna.
Someday we will have solid state artificial gravity. A possible clue to achieving that is figuring out how to generate some form of electromagnetic field that will go through every atom of spaceship and force the nucleus away from its center, creating subatomic dipoles inside atoms, resulting in gravitational attraction towards the floors and walls of spaceship without centrifugal force or thrust.
We don't know exactly how gravity works yet. We know that on Earth, things usually fall down. But science can't seem to figure out whether it's because things with mass attract eachother, or because things with mass distort space/time. Light is also affected by gravity even though it has no mass, so that suggests the second explanation. We think that the Higgs Boson particle is responsible for gravity, but not yet how or why. Figuring that out will be a game changer for future science and engineering.
@@bramweinreder2346
That's a bit of a mischaracterization. "Mass attracts mass" is a simplification of the more complicated "mass distorts spacetime and particles follow geodesics through spacetime that appear curved in 3-space," the two explanations are not contradictory, one is just more complete than the other. The Higgs boson is the carrier particle of the Higgs field, which gives mass to certain particles that were previously predicted to be massless. The boson itself does not create nor carry gravity.
@@the18thdoctor3 then I probably remembered some facts incorrectly, but I do remember that Newtonian physics doesn't play nice with general relativity.
I don't know why but for the longest time I have always viewed gravity as the flow of space/time towards the center of mass. I see space/time like a fluid that permeates and applies a force to all things, depending on the rate of acceleration due to mass. If we could figure out how to make space/time move, rather than trying to move through it, we could have artificial gravity and a whole new method of propulsion. Assuming my theory (which I probably am not the first one to come up with) is correct.
Or just spin a big wheel...
A lot of people understand that an object falling from a high tower on Earth gains 9.8 joules of kinetic energy per kilogram per metre of fall. (This is just the m*g*h formula with m set to 1 kg and h set to 1 m.)
But in *spaace* why can't acceleration *halfway to Mars*, at 1 gee, be somehow different? Be not the same thing as falling 30 billion metres, kinetic energy-wise? Not require building up 300 billion J/kg? Versus rocket fuel, which contains only 0.01 to 0.012 billion J/kg?
Well, it isn't. You can't carry that much energy if your energy reservoir is chemical rocket bipropellant.
Yeah, if I recall the authors of the expanse said the Epstein drive ran on “efficiency.” They didn’t know what technology could do it, but whatever it is it would have to be near perfect efficiency (mass to kinetic energy)
honestly think clicking around the deck plating in mag boots for 2 months will make up for the lack of g 😆
That doesn’t really help with any health issues, and mobility in space is actually a benefit over walking. I’d expect first missions to just go with zero g
@@ConHathy of course there's no health benefit, but I could see them assisting with a feeling of normalcy: walking around a deck but then still being able to disengage and propel yourself through perpendicular corridors to other decks. That, and mag boots are one of my favorite sci-fi devices.
To do this we need to have some infrastructure, we need refueling stations above the Earth and Mars. nuclear engine would get us there but the ship would have to be assembled in space not on earth
Yes, this was more to lay out how impractical thrust gravity is without some unknown technology being created. Now for the end when I talk about ignoring thrust gravity and just going for speed, that’s more realistic but yes would probably require refueling and wouldn’t be quite as fast as my idealized vehicles
@@ConHathy artificial gravity is in general not very practical. thrust is the closest that can be done with existing or near existing technologies but the right would be extremely expensive. a rotational method is a lot of complexity with little return
9:22 _"Nu-cu-lar"_ ...really?! ;-]
What about a nuclear salt water rocket.
What is the general consensus in the space-travel community re: the type of interior rotating carousel-type "gravity-maker" that was featured in 2001? Couldn't a rotating interior ring-type environment be provided to the ISS, ie as a separate module that astronauts on long missions in orbit could enter in order to experience some kind of semi-Earth-like gravity to help ameliorate their hunger for the comforts of "home" from time to time? Has this ever been proposed?
It takes a very big hull to accommodate a very small carousel, plus bearings to let it turn while the hull is spinless, plus a motor to drive the rotation against the resistance of those bearings, and of the air. And you don't want to be drifting in the free-fall part of the pressure vessel and crash into a spoke of the carousel. If its external radius is 4.3 m, so that it just fits a 9-m outer hull, and the one-gee radius is 3.2 m, the one-gee tangential speed there is 5.6 m/s. As you stand on the inner surface, your midsection is at that 3.2-m radius, your feet are at 4.2 m, going 7.35 m/s -- so bric-a-brac drifting in from the free-fall section, if that could happen, would hit them that fast -- and getting 1.3 gees.
Your head is at radius 2.6 m or -- if you're tall -- less, getting 0.8 gees or less. Nothing wrong with that. Not only can astronauts hold their heads high, this setup makes it easy.
But your scarce interior space, you've subdivided with at least three substantial walls that prevent floating hammer/heavy foot collisions, and ensure, when you are near the outer hull, either in the carousel or outside it, the wall nearest you is not moving with respect to you. Two of them rotating, one of them, maybe 2 cm away from a carousel wall, stationary. These two walls have small central round holes bounded at radius, I guess, 0.4 m, with the nonrotating one having a round screen door, so you can float in and climb down the 3.8-m ladder to gravity. The top of the ladder goes 0.7 m/s so seizing it and being accelerated to its speed is not difficult.
Spaceflights are long and those bearings must go at 16.7 RPM of the 4.3-m-radius wheel throughout them. Also not a big deal, but does imply noise and power consumption all day throughout the flight.
There's a much nicer option: a system that is almost entirely rotating, only some subsystems despun on gymbals. A system that uses the cosmos as a giant, noiseless, no-power vacuum bearing. Your feet get 1.00x gees, your head gets 0.99x gees, and all the pressurized, gravitied space can be undivided. The movie Stowaway shows it.
From such a space, you can get really good views through the floor windows. Sadly, the makers of Stowaway apparently didn't think of that.
@@grlcowan Thanks. Was just speculating. This would suggest that the Discovery/Jupiter mission in the Kubrick film, 2001---you may have seen it?---was not a very accurate prediction of artificial gravity on an interplanetary journey (the ship had the "big carousel" as being contained within the body of the ship). Of course, a lot of stuff in that film all turned out to be way off.
Thanks for the thoughts/any further thoughts!
@@RSEFX If you search for "long-heavy-tail option for spin gravity" you should find some of those thoughts.
Fusion rockets are a good idea
@Mr. Nobody Orion can't really provide constant acceleration because it uses pulsed propulsion, not rocket propulsion
you should use the relativistic rocket equation r = sqrt(b^2/(1-b^2)+R^2)-R+1/sqrt(1-b^2)-1😉
r = Menergy/Mship, R = Mpropellant/Mship, where Mship is the empty mass of the ship and b = v/c. The propellant mass is dead mass could be water. The Menergy is the energy used.
You can also let R = 0 if you don't throw dead mass out the back.
Also, you could store energy in a plasma and magnetic field externally to the ship the energy in this case can be quite large and the field would be many times the size of the ship
You could get this energy from a special solar collector near mercury and the field could collect cosmic rays, if you construct it right.
Interesting!!!
I thought about it while I was working on it but the speeds were small enough that it seemed a bit overkill less than 0.008% of C. I haven’t worked with relativity much so didn’t feel confident using and explaining it as well. But, as I understand it, the traditional rocket equation is actually over estimating the performance of the rocket as you get closer to C so it is still a conservative analysis
Nuclear. Let me know when you find the nuculous of an atom.
I know, I didn’t catch it until I was almost done editing
well, project orion.
There is no way for artificial thrust gravity unless with the nuclear salt water engine... but maybe not even with that.
even then the version of the nuclear salt water rocket would run into the same issue of thermal management than the epstein drive.
lighthuggers cab do this ;)
Yeah, all we need to do is make and capture a wormhole!
0:18 198K*
Have they not forgoten that rockerts requier fule.
What's the stuff you throw out the back going to push against, to give you forward motion, when you're in a vacuum?
The exhaust pushes on your rocket directly, it doesn’t need to push on air like a propeller (that would just slow it down and actually makes engines less efficient). The easiest way to think of it is conservation of momentum. If you start with a 1 ton rocket with 1 ton of propellant at rest, then shoot the 1 ton of propellant out the back at 100 m/s, conservation of momentum says the recoil will push the rocket at 100 m/s in the other direction, no air required.
@@ConHathy Thank you for your response! Yeah, that partly makes sense. But "re-coil"; there's a spring involved (if only in terms of wordplay) -- some tension that is being worked against, in the atmosphere? In vacuum it seems it would behave differently, although I've not experienced it. Would love to see an experiment of "testing thrust in a vacuum chamber." Thanks again!
@@kennethbeal for every action there is an equal and opposite reaction. your rocket exhaust is the action the reaction is your ship going forward. it does not need anything to push against. this is basic physics.
@@kazimirmcfoster5631 Thank you! Your first sentence holds true in non-vacuum. I'm not certain it behaves that way in vacuum. Telling me isn't sufficient[1]; if you can show me an experiment, then it will satisfy the science requirements.
[1] -- I'm not sure I'm conveying this properly; I'm not arguing, I'm not angry, and I'm not disagreeing with your assertion. I am saying, experimental evidence beats hearsay every time. In court, and in life. :)
@@kennethbeal the fuel isn’t pushing against anything so to say, it’s more so that when the fuel is expelled out the back, the equal and opposite force acts on the rocket. you can experience this if you take a brick and whilst sitting on a rolling chair throw it away from you, while the brick does encounter air resistance, it is the mechanism of force put into the brick that will push your chair backwards.
Script for a typical space science youtube channel: Here is a drawback to X, which I don't like. Therefore X is totally impossible. Here is a drawback to Y, which I like. I have cherrypicked two sources that say that this is not a big deal, therefore Y is totally the way to go. I am right and everyone else is wrong and stupid. The end. Now I need a clickbait title involving the word "impossible" or the phrase "don't do this".
And nasa is working on thes kinds of trip schortening engiens.
I really hope that in your future videos, you can pronounce "Nu-cle-ar" correctly, and not "Nu-kul-ur" like Dubya
Sorry but I gotta ask - are you saying "nucular" on purpose?
No, I didn’t realize I said it that way but editing and I am very ashamed
@@ConHathy I thought maybe it's a Simpsons reference, haha. Love your content by the way! I hope it gets the attention it deserves.
Watch the expanse guys
Great show! If I recall the authors of the expanse said the Epstein drive ran on “efficiency.” They didn’t know what technology could do it, but whatever it is it would have to be near perfect efficiency (converting mass to kinetic energy)
Wasn't it fusion with a catalyst tho
@@Pan_cak yeah, but I don’t think they every ironed out the mechanism that turned fusion into thrust so efficiently. I could be wrong though
But could antimatter work for extended 1g periods
It's so funny I wrote a comment in your other video about this and right after I posted the comment I saw you had this video and came right over to watch it. Going to a question I had about this concept is, I think maybe an idea we could look at two different types of rockets. One that's designed for leaving a surface of a planet or place and another for the long road travel from say planet to planet. Designing a rocket to fly through the air and fighting gravity as it would leave the atmosphere surly is going to have a different design then one that would stay in space and fly through space. Your thoughts on that please?
I'm sorry but you do need Elon musk girlfriend in the thumd nail
Why are you talking about thrust to weight ratios? Everything in space is weightless. You want to look at formulas that use mass, not weight, right?
If you want to produce artificial gravity then you care about thrust to weight. If you have an engine that’s 100kg, it needs to produce more than 100kg of thrust to accelerate at 1g (if you ignore fuel)
@@ConHathy ah ok. The 1g creates the weight, thanks
@@ConHathy FYI, from a stand still, you only need to accelerate at 1G for 22 hours to get halfway to Mars (18 million miles) when it's closest to Earth. Then decelerate for 22 hours to arrive. So you're only looking at 44 hours of thrust needed for the entire trip.
Burning gunpowder mixed with oxygen powder with be fastest. Mix it up and pack it into an acre wide and 100 meter long tube, and swoosh we go.
Epstein drive FTW
Nucular?
I know, I didn’t hear it until editing
Some comments halfway in. Space is very cold. So we're probably good on that :) other than that, isn't it true that the faster you're going, the more fuel you need for the same acceleration because you posses more kinetic energy which makes you heavier or something? Not sure if that's true but it's how someone explained it to me. One way to overcome this is by accelerating to a certain optimal cruising speed, rotate in flight, decelerate, rotate again on the next day, accelerate etc.
1. The internals of a ship are MUCH warmer than hydrogen's boiling point
2. The sun exists, and there is no shade in space.
@@Wise_That says he while throwing a whole forest of shade on me 😁
That's gonna be a problem when they want to use fusion reactors in space. Helium-3 is only a smidge heavier than hydrogen, be it twice as heavy. But it has a much lower boiling point.
If you're talking about relativistic effects then that wouldn't apply unless you're going near the speed of light. And anyway I think that you'd still "feel" the same acceleration per fuel spent, it's just that an outside observer would see you speeding up less, and you'd see the space around you speeding up less (and also contracting in length).
@@ryanmccampbell7 I'm only talking about the fact that helium-3 takes more effort to keep in liquid form as hydrogen. After some quick fact checking, hydrogen boils at 20 Kelvin, and helium-3 at 3.19. But per energy output, the amount of helium-3 required is negligible compared to other fuel sources. So that makes it easier again.
@@bramweinreder2346 I was referring to the "the faster you're going, the more fuel you need for the same acceleration".
Arguably thrust-based gravity is "better" than Earth. As there is no gravity gradient to worry about or rotating reference frame issues.
It's also extremely difficult to accelerate at any appreciable fraction of 1 G using a rocket thruster for more than a few minutes at a time.
I cringe every time I hear someone pronounce “nuclear” as “nu-kyoo-ler”. “New-clear.” Say it right lol. Do they spell it “nuculus??” No. “Nu-cle-us.” Hence, “nu-clear.”
😂
I know, I didn’t even know that’s how I pronounced it until I heard it in editing
@@ConHathy that must’ve been a shock, a gain of self awareness can be jarring. Hopefully you had a good laugh.
Loved the video man, keep up the great work👌
Yes, but can Epstein Drive do it? ;)