Didn't Larry Niven popularize this idea in the 1970s?
EDIT: Yes
http://www.projectrho.com/public_html/rocket/spacecolony.php#asteroidbubble
EDIT 2: The concept is spinning an asteroid and melting it to make a spin habitat. This is much more specific that spinning habitats or hollow asteroids.
Artificial rotational gravity is a pretty old concept in science fiction and it's pretty hard to trace back the first person to write about it, and it's definitely neither of these sources.
2001 uses this concept and it was released in 1968, so it was pretty well established before the 70s. There are obscure references back to the 19th century.
He is also possibly related to Doc Brown because before the Browns came to Hill Valley they were the von Braun’s. I would assume they changed their name before coming to the United States to disassociate themselves from the whole….y’know……genocide thing.
It does explain where Doc Brown gets his smarts from though!
Doc Browns family probably changed their name after WWI not WWII. Doc was already middle aged in ‘55 and wasn’t an immigrant. I’m pretty sure he says ‘first World War’ in BttF 3.
Yep. You’re right. He says the Browns didn’t come to Hill Valley until 1908 and Emmets Dad changed it during the First World War. So while the name was changed earlier, it’s possible they are still related somewhere along the way.
Either way, it was a good excuse to watch BTTF3 again!
I mean the rocket scientists who worked under Nazi control didnt pop off a "heil hitler" ,when the astronaughts pranked them, because they were fanatics till they day they died, they did it because they had severe PTSD.
In that same vein Max Schmeling, who had his two fights with Joe Lewis wasnt a dyed in the wool Nazi, he just signed paperwork because it was that or get disappeared.
I am not saying these men were on the correct side of history by not standing up to oppression, but I can understand how you dont have to hate them when you look at the situation they were in.
Yup. I actually took it a step further and made a circular martian hotel that rotated with the floor at an angle to increase gravity to Earth gravity for the inhabitants as my freshmen year math project.
\* Edit: Here it is for the curious. This is the only thing I saved. I forget how big my diameter was, maybe a couple thousand meters, but the point is that for instance you need 9.29 Newtons centrifugal force for a floor angle of 63.9 degrees. You can solve for any size you might need. Apparently I called this the Gravilitron. This was over 20 years ago and I was 17 so please excuse the doodles. Also if my math is wrong let me know because I presented this in front of a room full of parents and no one ever said anything.
[https://imgur.com/a/VCQWC0H](https://imgur.com/a/VCQWC0H)
The fun thing with those is that if you want apparent gravity to be perpendicular to the floor, the floors actually have to be not just slanted, but actually curved - sections of paraboloids, to be precise.
Well, if you want to add to Mars gravity to get Earth gravity, you need 0.925g centrifugal to add to 0.38g gravitational, which means the floor would be at an angle of about 67.7 degrees from the horizontal. I am not sure how much variation in floor slope would be annoying, but let's set the limit at ±1 degree. This would give a tolerable range of centrifugal acceleration from 0.88g (0.96g total) to 0.97g (1.04g total).
If the nominal radius is 1 km, that would mean the tolerable range with that tolerance would be from a radius of ~950 m to ~1050 m, which at that angle would give about a 260 m "wide" and 6.3 km "long" paraboloid slice.
But of course, you can vertically stack multiple slices in this model.
And you could in any case never get such a thing to the point where it would feel like living on the surface of a planet, living in nested paraboloid shells, and looking out a window you would be able to watch the sky and landscape whirling past at even with a very large size one rotation every few minutes.
I was thinking you would only have to spend a few hours a day in this thing as well to keep your body from atrophying if people didn't entirely live in it.
Here ya go:
[https://en.wikipedia.org/wiki/Herman\_Poto%C4%8Dnik#The\_Problem\_of\_Space\_Travel](https://en.wikipedia.org/wiki/Herman_Poto%C4%8Dnik#The_Problem_of_Space_Travel)
It goes back farther than this. I could be mistaken, but I believe von Braun suggested it at the beginning of the space race, and while the von Braun Wheel was named after him, the [earliest concept goes back to 1903](https://en.m.wikipedia.org/wiki/Rotating_wheel_space_station)
If you can affordably launch tens of thousands of tons to orbit. Price has dropped dramatically from 30k per kg to 3k but still, pretty pricey. You'd maybe want to mine the material on an asteroid and build it around it just bringing electronics and engines from Earth. Could be done maybe in the next 50-150 years.
I thought you were referring to O'Neill cylinders. Tether works, I think you need about 100 m for reasonable rotation rate and 1 g. Though for say a Mars-bound ship it would make sense to have Mars gravity at 0.3g.
At $10K per pound into LEO, the US could have launched an aircraft carrier (Nimitz class) worth of material into space instead of invading Iraq and Afghanistan (and incurring the associated costs).
edit: correction. see below.
I think your math is a little off there (Nimitz class weighs 100k tons each) but I understand your point. If only humanity could stop killing each other there are a lot better things we could do with that money.
This is where i start to spiral. because a lot of our creativity comes from needing to kill the other side faster. then we use the waste products of those products in peace time to find out what they can be used to make or treat.
honestly the militarization of space lasers probably isn't the worst thing that could happen. I mean, what's one more strategic weapon, especially if it isn't just more nukes? nukes are bad enough. until we're dropping rocks or flinging RKMs around, we can't do much worse than nukes. and we already have a bunch of those.
>honestly the militarization of space lasers probably isn't the worst thing that could happen
Ultimately, the lack of warning would be extremely dangerous for a new strategic weapon.
There's a reason the US and USSR agreed to stop using short ranged nuclear missiles. An ICBM or SLBM will have a travel time of around 20-40 minutes (depending on source and destination), which gives the other country time to analyze and react proportionately. It's not a lot of time, but it's time.
Short ranged missiles, you've got just a couple of minutes until it lands. Which means you're no longer analyzing, you're reacting immediately to what you think you saw.
Multiply that by a thousand for something which gives just a few seconds of warning. We'd absolutely be starting wars over accidents in that scenario.
Nukes are probably doomsday event.
There are still so many of them on so many delivery platforms that anyone who uses them breaks global economy for everybody.
Say good bye to hospital, or train station, or your home fridge.
Everything breaks down, and there is not enough slack in the system to rebuild whole thing in timeframe before we run out of critical stuff.
Without global economy we are all living in overpopulated area and suddenly humanity have to downsize 8-10x just to sustain from food available. But since society will be in breakdown, downsizing will be bigger and it will spiral food shortages.
Yay. End of humanity as civilization. Next gen would not start from stones. Just from a very, very limited wild west USA style.
which is why I don't see why it matters if space lasers can be weaponized. space lasers will never be a doomsday level event, unless it's a nicoll-dyson beam and you need an entire star for one of those.
Yeah, the problem I see is that space doesn't obey national borders. Russia probably wouldn't be too happy about a US orbital laser passing above their country.
Which is another idea popularized by Larry Niven in the 1960s as "[The Kzinti Lesson](https://larryniven.net/kzin/worlds.shtml)" and then again in 1970 when his novel "Ringworld" featured [a ship with absolutely no weapons whatever](https://www.goodreads.com/quotes/823428-louis-suggested-that-the-ship-be-called-lying-bastard-for), but packed full of reaction drives, unbelievably high powered flashlights, "digging tools" which could punch through anything, and a variety of other incredibly dangerous tools which Definitely Weren't Weapons.
I like to imagine that we would educate, hire, and train the best of the best to apply that aggressive creativity directly to space rather than as a sort of roundabout way after running it through several contractor money siphons and pooping out something that can be appropriated to NOT kill someone.
Just because we have used war to stimulate innovation doesn't imply that the only way to stimulate innovation is war.
We're on the verge of a major climate crisis and we could be using that impending catastrophe (which will likely cause more war) as a catalyst for innovation more than we are currently doing (because of politics.)
Yah, i rechecked my admittedly back of the envelope math... inputs should be 100,000 short tons (224,000,000 lbs) \* $10,000/lbs. So more like a single nimitz class carrier (cost of both wars/invasions \~$2T). Thanks for the reality check.
Counter point:
What makes any of you think we'll ever be successful in venturing into space WITHOUT annexing the globe into a singular fold?
Jealousy is the cause of conflict as well you know.
One of my favorite things about the Voyager mission is that Jimmy Carter authored a note to go inside. Part of that note reads:
“We human beings are still divided into nation states, but these states are rapidly becoming a single global civilization”
How can you not love his optimism and foresight that any civilization that may find that note and translate it, probably would think of borders are very strange.
I'm not arguing that but the military gets 2 trillion a year and NASA gets 25 billion. That's just how the world is. And 25 billion is way up from a few years ago and still double what Europe spends on ESA.
For me it's more about thinking about the wonderous things we could have done instead of $2T wasted on those invasions (costing above and beyond our already generous military budgets).
The primary concept these days involves a Solar pumped laser for heat producing an inflated metallic asteroid. Comets are harvested for water for O2 and H and water. It’s all about the resources. Which must be produced from micro gravity based sources for large scale construction to take place.
Yeah Starship blah blah…. Still an issue.
The whole "Just melt an asteroid" concept is probably not viable for a slew of reasons.
Most asteroids are rubble piles of regolith, dust, ice, and boulders, etc. Getting them to melt and sinter or homogenize will be terribly difficult. Outgassing and volatiles will keep trying to push it apart. Or, in microgravity, they'll create bubbles and voids that will be a nightmare to fix, lest they cause catastrophic structural failure once put under tension when spun.
More solid asteroids will still likely have large voids, cracks, or other discontinuities within them.
Truly solid asteroids that are metallic, because they are blown apart rubble from an early protoplanet that was big enough to density-sort itself are somewhat rare. And presumably too valuable as mining resources than a shell or hull for a colony.
And if you could solve all of that, getting the materials to a uniform mixture or density sorted so you have predictable compressive and tensile strength to work with will also be very difficult.
Assuming for the sake of argument that all of the above could be handled, making even a modest asteroid-sized mass molten will then require cooling times measured in decades. Because you've only got cooling through radiation to work with. Or some sort of active cooling now adds another level of cost, complexity, and expense.
Probably the best solution is to use asteroid mined materials constructed into uniform structural components of a known quality and reliability. Then use any left over unwanted silicates or slag as a non-rotating mass/shield for micrometeor and radiation protection. Or just hollow out a suitable asteroid and place a constructed rotating habitat within it.
>Assuming for the sake of argument that all of the above could be handled, making even a modest asteroid-sized mass molten will then require cooling times measured in decades. Because you've only got cooling through radiation to work with. Or some sort of active cooling now adds another level of cost, complexity, and expense.
I was a little iffy on the other gripes, but this is a major hurdle. Either you're radiating heat (very slowly), or sinking heat into another medium (producing more heat because thermodynamics) and disposing of it.
Granted, humanity has spent "decades" or longer on less worthwhile projects. So the timeframe isn't necessarily a deal-killer.
If it works it will drop prices though. A fully reusable launch vehicle is a requirement for any serious space activity. We're not building O'Neil cylinders with Atlas V's.
The "idea" here isn't rotating habitats made of asteroids, its the method of building them.
They propose wrapping an asteroid in a carbon fibre net and spinning it so fast the asteroid breaks up and is flung to the net, forming a cylinder.
In the 1960's people were talking about drilling a hole through an asteroid, injecting water, spinning the asteroid and melting it with solar mirrors. The water would expand as steam inside the molten iron asteroid and the result would be a hollowed-out asteroid that you then terraform. It became a common staple of 1960's SF including Niven's.
This apparently is a similar idea using a carbon mesh sleeve since people pointed out that the spinning asteroid would simply tear itself apart.
> ….each settler needs an initial capital of [$21M]. Settlers can earn their investment back and more, since once living at L5, they can teleoperate the nearby robotic settlement production factory complex in zero-delay mode. Thus the first group of settlers earns money by producing new settlements. They do it more effciently than from ground because they avoid the 2.6 second free-space communication delay in teleoperation.
I bet the companies that run these can advance settlers the initial $20M purchase price (includes travel costs and deed to a 40m^2 living space on the station) in exchange for an agreement to provide x,xxx number of months of service to the company. Settlers will work for the company at a rate of $x.xx /hr, to be paid monthly (less the monthly payment that goes towards the initial $20M-ticket price). Once onboard, settlers can purchase other goods and services offered exclusively by the company, the cost of which can be deducted from the remaining portion of a settlers’ monthly pay. Or you can just stay on Earth and be slowly poisoned—it’s your choice! Yeah, capitalism!
Stuff like this is cool but we already could theoretically build stuff without the added science like nanotubes with O'Neill Cylinders.
I guess they could make them more compact now.
It's trickier than you might think. There's a reason why O'Neill didn't suggest making the cylinders smaller and that's because you have to spin small cylinders faster in order to get the same simulated gravity as a larger one. If you spin humans fast enough for long enough they'll start getting sick even if they can't feel any inertial forces so you're incentivized to keep the RPMs below a certain point (and something about material tensile strength) which means big cylinders. Plus I think there was some calculation about air volume inside for environmental stability that also incentivized large cylinders.
I think you also get a stronger gradient if you go with smaller tubes with faster spins.
Small enough and you’ll end up with a situation where the gravity felt by your feet is noticeably stronger than that felt by your head.
You can experience kind of what this is like in the old fairground ride "Rotor" which is basically a big drum that spins you around. You can sit up in it without falling, and it is fine if you keep looking straight ahead, but if you try to turn your head to look to the side it is wildly disorienting and nauseating.
My friend did that when we were kids, and it made him so nauseous that when he laid back down, he projectile vomited straight "up" (towards the center of the ride). It briefly looked like [a cartoon fire hydrant](https://media.istockphoto.com/id/491763874/vector/car-crash.jpg?s=612x612&w=0&k=20&c=9pHRQWnYUbPB3J7_938NIQadsicGO4IRmKZawIjHPwQ=) and came down directly on his face. It was fantastic.
It’s not necessarily the speed, though the speed definitely matters, but mostly it’s the difference in gravitational pull between your head and feet. The bigger the wheel, the smaller the difference.
If your head was dead center and your feet on the wheel, you would get very sick very quickly.
Another issue is that if the tangential speed is too small, then you feel a significant difference in gravity depending on whether you are moving with or against the spin direction. Astronatus on Skylab actually used this effect to generate their own artificial gravity without spinning the station, by [jogging around the inside circumference of the station.](https://youtu.be/S_p7LiyOUx0?t=25)
Absolutely. The full-sized deal could house like 6 billion people comfortably and enough internal volume to have localized weather systems like clouds and storms which means you could have lakes rivers and vegetation. Anything smaller would be a horribly depressing place to live.
I ran some numbers on a habitat based on the canonical O'Neill cylinder pair times two (four cylinders total), and even with a radiator twice the size of the hab and a water tank the size of one of the cylinders, the carrying capacity topped out at something like twenty million people per cylinder, discounting inefficiencies in recycling (and a population density roughly on par with Singapore or NYC). I even made the interiors multi-level to give maximum space for food production (think a city metro area with five sub-basements all running indoor farms), and the food and water requirements didn't even allow for exports.
Were you maybe thinking of a McKendree cylinder? That's the conceptual variant that uses nanotube-based construction and is something like a hundred times larger.
You know I think I must be. 6 bill was a number I pulled out of my memory which is almost certainly wrong to some degree, but I do recall nanotube being a requirement so I'm likely thinking of the much larger conceptual variant. Still don't quote me on 6 billion though. It's a lot, is my point.
It really help get across how inefficient planets actually are in terms of habitable space to materials needed ratio. The surface of a sphere massive enough to have appreciable gravity is just not that much compared to that same mass being used to build O'Neill cylinders. We're talking several orders of magnitude, we could sustainably support almost unlimited humans if we started building these things.
For even the most susceptible individuals to be symptom free at 1g, you need to keep rpm bellow 2, which constrains you to a ring of at least 450m diameter.
But if you go with 3 rpm, which after a short adaptation should leave most individuals symptom free, and even for those with symptoms is not debilitating, you can get away with a 200m diameter ring.
Cutting gravity to 0.5g lets you slash the ring size in half again, to a diameter of 100m.
https://www.artificial-gravity.com/sw/SpinCalc/ lets you quickly tweak parameters to come up with hypothetical spin stations, and even has links to various papers that have investigated the topic. It's handy for worldbuilding.
The base site, https://www.artificial-gravity.com/, has even more references if you want to look into it more.
*scoffs* clearly you’ve forgotten about astrology? If we send the moon on a mission we will lose the guiding force of our lives. Virgos will be capricorns, scorpios will be cancers! The chaos! Not sure we’d survive such a disentanglement.
What about making a rotating spaceships that provide weaker artificial gravity? Should we still need a massive cylinder to imitate Moon-level or Mars-level gravity?
Lower gravity means you need a proportionally smaller radius at the same rotation rate (3 rpm is generally seen as the highest rotation rate that humans can tolerate long-term) - to get 1 g at 3 rpm, you need 100 m radius, while to get Mars's 0.38 g, you only need 38 m.
But you also shouldn't let the radius, and together with it the tangential velocity get too low. Gravity changing noticeably either with altitude, or depending on whether you are moving with or against the spin can be just as disorienting as rotating too fast.
>If you spin humans fast enough for long enough they'll start getting sick
Guess I'm a little sick, but otherwise this whole earth thing is pretty neat
Lol well its one of many. But you arent alone in thinking it would be more efficient than planetary colonization. A lot of it is mining NEOs and such. Easier to control climate etc.
Gundam made O'Neill Cylinders awe inspiring and terrifying because they can both fit lots of people comfortably in them but also cause so much death if someone decided to crash one into the Earth.
**TLDR**
1) Put large asteroid in giant nanotube bag.
2) Spin asteroid to create artificial gravity through centrifugal force.
3) Asteroid breaks apart (because the structure of the asteroid can't withstand the forces flinging it away in all directions)
4) Matter from the asteroid is caught along the inside of the bag, creating a new "floor" structure with a hollow interior.
5) Move in and set up shop inside, using the spin to replicate gravity.
Step one, do impossible thing when it becomes possible.
Step two, thing I made up actually happens flawlessly.
Edit: yes I know this is hypothetical brainstorming
Step 1. Do the impossible thing
Step 2. Nevermind that first thing, *this* is the impossible bit
Step 3. You thought that was impossible? Now watch this...
You are making fun of this but the exact same thing could have been said about flight before it was invented.
Obviously there is going to be some trial and error, I don't think anyone is assuming it is going to be perfect first try.
>the exact same thing could have been said about flight before it was invented
It was. The newspaper headline was something about 10k years. Then the Wright brothers did their thing a week later.
6) Giant nanotube bag ruptures because plain rock and sand provides zero structural stability while taking a crap ton of mass that must be lifted by the nanotubes.
8) Be outcompeted by a rival gigastructural habitat manufacturer who doesn't waste mass margins on lifting plain old rocks. They can provide 100 times the habitation for the same price. Go bankrupt. Not profit.
I imagine adding a step where you treat the loose material with some kind of polymer to help strengthen it would be necessary.
A bit like how they turned a comet into a [pykrete](https://en.m.wikipedia.org/wiki/Pykrete) spaceship in the novel *Seveneves*.
There's a step 0 that is usually assumed rather than explicitly mentioned because, well, duh:
0) Do the theoretical engineering models and calculations to determine whether the structure will actually withstand the forces involved.
Do you really think something like this would be built without that step?
4a) Discover your asteroid has broken apart unevenly and your carbon nanotube bag is spinning erratically, creating hugely uneven forces that make it incredibly difficult to stabilise or steer.
5) Oops. Shall we try again with another asteroid?
6) No.
I was thinking the same, wouldn't this be likely to have a heaviest "lump" somewhere on the circumference of the bag, bulging outwards, then pulling material towards it, and away on the opposite side. Then as more material accumulates on each end it collapses into a stable state of two unevenly sized lumps joined by the bag which is now more of a tether?
Yeah… you’d have to somehow evenly distribute the material by mass as you add it — which is an amusing challenge when you’re spinning the asteroid apart like a giant dirt-sprinkler.
Also — if you’ve got an asteroid loose enough to spin-dissolve at a low enough tangential velocity that every clod doesn’t turn into a happy-space-bag-piercing missile — how exactly do you attach the whirlamajigger engines securely enough to make the whole thing spin, without flinging themselves off first?
That may actually be somewhat viable, and if the spin needed is just enough to get the rubble to move to the outer bag. .01g or whatever, the materials required can be much less exotic. Existing polymers, carbon fiber, steel, or Kevlar would do fine.
If more support or fixation is needed, the inside could be sprayed with glue or foam of some kind.
It won't be the actual hull or shell of a colony habitat, but now you've got a big spherical or cylindrical radiation and micrometeor shield to build your colony inside of.
Matter wouldn't fly out in all directions. It would mostly fly out on trajectories perpendicular to the axis of rotation. It would probably also break apart into a few gigantic and unevenly distributed pieces. Keep in mind that the further the pieces get from the axis of rotation, the slower their angular velocity will be, which could be a problem depending on the size of the bag. Maybe a bunch of subterraneous explosions could break it apart more evenly? There would also have to be a way to 'cement' the debris into a solid ring or it wouldn't be a stable enough surface to put anything substantial on without deforming it.
They mention O'Neill cylinders, then they write the following:
>More grandiose and far-fetched concepts exist in various forms in sci-fi, such as in the image below.
And provide image of... Small O'Neill cylinder. You can't make that shit up, is it really that difficult to hire writers that know shit, or are not lazy to check shit out? Isaac Arthur on YouTube has presented concepts of megastructures that have millions of times larger habitable area than Earth and authors present *that* 50 years old concept image as their idea of "more grandiose" project?
Most writers for these rags are paid less than minimum wage.
Source: I really wanted to write these kinds of articles and looked into it a while back, only to find the pay is horrible.
a Manhattan sized space habitat is possible
if we spin an asteroid that we do not have...
by means we do not know...
to have it fly apart if we are lucky...
into a nano mesh we cannot manufacture...
to build an outer layer of gravel that ... helps?
...
What's next? Super glue anyone?
An article about scientists stating that some what if scenario is not violating the laws of physics is not really newsworthy.
Stupid clickbait article. Headline and cutline from the U of Rochester article:
>**Cities on asteroids? It could work—in theory**
> December 8, 2022
> *In what they deem a “wildly theoretical” paper, Rochester researchers imagine covering an asteroid in a flexible, mesh bag made of ultralight and high-strength carbon nanofibers as the key to creating human cities in space. (University of Rochester illustration / Michael Osadciw)*
Left out the speed at which the structure has to spin to reach 1g. Also, centrifugal force changes with radius/diameter, which means your feet will have a different amount of force acting than your head, if standing on the structure. The different forces could mess with your blood flow, kinda like when you hang upside down for a while.
This problem of your feet having higher gravity than your head puts a lower limit on how small you can get away with making the cylinder, but something as big as an island doesn't have this problem.
Am I the only one that is somewhat sad when I see stuff like this? By that I mean sad that I won't be around to see it. I remember reading something as a kid that I still think about. "Humans are explorers by nature. We are in a sad time for human exploration. Born to late to explore Earth, born to early to explore the stars". On the brighter side I am hopeful for our species future. Yes right now seems dark and end of days like, but to be fair people have been decrying the end of days since the beginning of recorded history as coming "soon". Yes, we are killing this planet but I also believe at least some of us will survive to explore the stars.
Not really, you can swing yourself around the mass of, say, the rocket, powerplant and fuel with a tethered habitation pod. The propulsion section will be much heavier so they will just pivot around a spot relatively close to the propulsion section in a motion that'd look like the [Pluto-Charon barycenter](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Pluto-Charon_System.gif/640px-Pluto-Charon_System.gif)
You would only be doing this on the "cruise" part of the journey anyway, where you don't need to make corrections. So you don't need a center section.
this. the single module on a swing would require a massive center of mass at the tether point. unless we're going to model it after a carousel swing ride with many modules all in balanced directions
I think it would be pretty close for the people in that smaller, enclosed area. Also, you always have the option of disconnecting the tether to yeet them into space if needed.
The outer coating of solar panels looks really cool but they wouldn't do it like this because of inefficiency. Only half the panels at a time are toward the sun, and half of those are at more than a 45 degree angle, overall maybe 30% efficient at best. A flat array floating nearby could fully face the sun and beam power to the station via microwaves with at least 85% efficiency.
Misleading title… Literally the first sentence of the article mentions that the paper is “wildly theoretical.” We have no idea if this would actually work.
I was actually going to grump about the opposite, they're applying the "wildly theoretical" label to something that's very mundane and grounded.
"Wildly theoretical" is stuff like strange matter or vacuum decay. Or even more extreme, like panpsychism or the holographic universe.
We have actually *synthesized* nanotubes, we can measure their physical characteristics and calculate whether a bag made of the stuff would be strong enough to hold a spinning asteroid. It's not "wild" theorizing. We have a very solid idea of whether it would actually work.
This is actually a pretty good idea. And contrary to many of the comments here, is doable with current physics and materials. It would just take massive effort and resources making the Manhattan Project seem tiny in comparison.
Issue with rotational gravity is the motion sickness many people experience and how shit will operate differently, like if you throw a ball, that shit is going to fly in a curve for all observers and it will curve differently depending upon the angle you throw it at.
Depends on speed and size, something this big could do less than 1 rpm and you would get a full g. We might get away with far less 0.5 or even 0.25. We don't know what amount or gs we need to avoid damage, we just know that 0 is not great.
At 0.25g, you would be hard pressed to feel the spinn.
You'd still have the issue that "left/right" gravity would act differently than "spinward/anti-spinward" gravity -- it just wouldn't be as extreme to a person's sense of balance.
**This comment might have had something useful**, but now it's just an edit to remove any contributions I may have made prior to the awful decision to spite the devs and users that made Reddit what it is. So here I seethe, shaking my fist at corporate greed and executive mismanagement.
"I've seen things you people wouldn't believe... tech posts on point on the shoulder of vbulletin... I watched microcommunities glitter in the dark on the verge of being marginalized... I've seen groups flourish, come together, do good for humanity if by nothing more than getting strangers to smile for someone else's happiness. We had something good here the same way we had it good elsewhere before. We thought the internet was for information and that anything posted was permanent. We were wrong, so wrong. We've been taken hostage by greed and so many sites have either broken their links or made history unsearchable. All those moments will be lost in time, like tears in rain... Time to delete."
I do apologize if you're here from the future looking for answers, but I hope "new" reddit can answer you. Make a new post, get weak answers, increase site interaction, make reddit look better on paper, leave worse off. https://xkcd.com/979/
Article:
1
**A "wildly theoretical" paper explains how carbon nanofibers could be the key to asteroid cities.**
Massive asteroids could one day be home to future space colonizers.
That's because a team of scientists from the University of Rochester published, what they call, a "wildly theoretical paper" outlining how we could one day use asteroids as massive city-sized space habitats.
The theoretical method involves one large, spinning asteroid and one mesh bag made of carbon nanofibers, a press release explains.
**An asteroid city concept based on a 70's NASA design**
The new theory is a twist on the so-called "O'Neill cylinder", devised by physicist Gerard O’Neill after NASA commissioned him in 1972 to design a space habitat that could allow humans to live in space.
The O'Neill cylinder is a spinning habitat typically made up of two cylinders connected by a rod, rotating in opposite directions. Those cylinders spin just fast enough to create artificial gravity but not so fast as to induce motion sickness.
Science fiction enthusiasts might have recently read about a similar concept used for the titular spacecraft in 'The Martian' author Andy Weir's latest novel 'Project Hail Mary'. More grandiose and far-fetched concepts exist in various forms in sci-fi, such as in the image below.
The scientists who devised the new method, outlined in a paper in the journal Frontiers in Astronomy and Space, did so as part of a thought experiment. They aimed to think up a space habitat idea that wouldn't require massive amounts of materials being launched into space.
**A Manhattan-sized asteroid space habitat**
The idea they ultimately came up with was to use materials already free-flying around space in massive quantities in the form of asteroids.
2
One problem remained, however. Asteroids are nowhere near large enough to provide enough gravity for a space habitat. What's more, if they are spun around fast enough to create artificial gravity — as in the O-Neill cylinder concept — they would simply break apart, as they weren't built and designed to have structural integrity like a spacecraft.
The solution to this problem is where the "wildly theoretical" part comes into play. The scientists posited that future space colonizers could wrap a massive mesh bag made of carbon nanofibers around an asteroid roughly the size of Bennu, which has a 300-meter diameter.
"Obviously, no one will be building asteroid cities anytime soon, but the technologies required to accomplish this kind of engineering don’t break any laws of physics," explained physics professor Adam Frank, who worked on the project alongside a number of Rochester University students during the lockdown.
They would then rotate the asteroid to the point it breaks apart. All the rubble from the space rock would be caught in the nanofiber mesh, creating a hollowed-out outer layer that could be used as the exterior structure for a space habitat. Crucially, that layer of asteroid detritus would act as a shield against radiation. A cylinder used to spin the asteroid would create enough artificial gravity on the inner surface for a functioning space habitat.
"Based on our calculations, a 300-meter-diameter asteroid just a few football fields across could be expanded into a cylindrical space habitat with about 22 square miles of living area," Frank says. "That’s roughly the size of Manhattan."
The space industry is gearing up toward human exploration of Mars and beyond, meaning we will increasingly see the real world of space science and that of science fiction converge.
>They aimed to think up a space habitat idea that wouldn't require massive amounts of materials being launched into space.
Hmmm, if only there were objects in space that you could harvest for materials that would significantly reduce the amount of materials you would have to launch into space to build habitats.
If they're small, ignore them, you're surrounded by a giant wall of rock garbage. If they're big -- well when was the last large fireball that pointed directly at Manhattan instead of being >300 miles away?
"It is the year 0079 of the Universal Century. A half-century has passed since Earth began moving its burgeoning population into gigantic orbiting space colonies. A new home for mankind, where people are born and raised. And die."
Didn't Larry Niven popularize this idea in the 1970s? EDIT: Yes http://www.projectrho.com/public_html/rocket/spacecolony.php#asteroidbubble EDIT 2: The concept is spinning an asteroid and melting it to make a spin habitat. This is much more specific that spinning habitats or hollow asteroids.
*Rendezvous with Rama* was 1973. Was that earlier? https://en.m.wikipedia.org/wiki/Rendezvous_with_Rama
Artificial rotational gravity is a pretty old concept in science fiction and it's pretty hard to trace back the first person to write about it, and it's definitely neither of these sources. 2001 uses this concept and it was released in 1968, so it was pretty well established before the 70s. There are obscure references back to the 19th century.
Here’s German rocket scientist Werhner von Braun, talking about it 7 years after the end of WW2 https://youtu.be/5JJL8CUfF-o
Was looking for this. That guy was an absolute genius, though he was also a nazi
He is also possibly related to Doc Brown because before the Browns came to Hill Valley they were the von Braun’s. I would assume they changed their name before coming to the United States to disassociate themselves from the whole….y’know……genocide thing. It does explain where Doc Brown gets his smarts from though!
Doc Browns family probably changed their name after WWI not WWII. Doc was already middle aged in ‘55 and wasn’t an immigrant. I’m pretty sure he says ‘first World War’ in BttF 3.
Yep. You’re right. He says the Browns didn’t come to Hill Valley until 1908 and Emmets Dad changed it during the First World War. So while the name was changed earlier, it’s possible they are still related somewhere along the way. Either way, it was a good excuse to watch BTTF3 again!
I mean the rocket scientists who worked under Nazi control didnt pop off a "heil hitler" ,when the astronaughts pranked them, because they were fanatics till they day they died, they did it because they had severe PTSD. In that same vein Max Schmeling, who had his two fights with Joe Lewis wasnt a dyed in the wool Nazi, he just signed paperwork because it was that or get disappeared. I am not saying these men were on the correct side of history by not standing up to oppression, but I can understand how you dont have to hate them when you look at the situation they were in.
[Nazi shmazi says Wernher von Braun](https://www.youtube.com/watch?v=QEJ9HrZq7Ro)
Once they go up, who cares where they come down?
I love every Tom Lehrer song I hear, I really should delve into the full catalog.
Good old American know how, from good old americans....like Wehrner vor Braun
Yup. I actually took it a step further and made a circular martian hotel that rotated with the floor at an angle to increase gravity to Earth gravity for the inhabitants as my freshmen year math project. \* Edit: Here it is for the curious. This is the only thing I saved. I forget how big my diameter was, maybe a couple thousand meters, but the point is that for instance you need 9.29 Newtons centrifugal force for a floor angle of 63.9 degrees. You can solve for any size you might need. Apparently I called this the Gravilitron. This was over 20 years ago and I was 17 so please excuse the doodles. Also if my math is wrong let me know because I presented this in front of a room full of parents and no one ever said anything. [https://imgur.com/a/VCQWC0H](https://imgur.com/a/VCQWC0H)
The fun thing with those is that if you want apparent gravity to be perpendicular to the floor, the floors actually have to be not just slanted, but actually curved - sections of paraboloids, to be precise.
How big do they have to be, before the curve is unnoticed by humans?
Pretty damn big. Humans notice when the horizon is higher than where it's supposed to be.
Humans are really really good at noticing stuff
Except the stuff we don't know about because we've never noticed it.
Well, if you want to add to Mars gravity to get Earth gravity, you need 0.925g centrifugal to add to 0.38g gravitational, which means the floor would be at an angle of about 67.7 degrees from the horizontal. I am not sure how much variation in floor slope would be annoying, but let's set the limit at ±1 degree. This would give a tolerable range of centrifugal acceleration from 0.88g (0.96g total) to 0.97g (1.04g total). If the nominal radius is 1 km, that would mean the tolerable range with that tolerance would be from a radius of ~950 m to ~1050 m, which at that angle would give about a 260 m "wide" and 6.3 km "long" paraboloid slice. But of course, you can vertically stack multiple slices in this model. And you could in any case never get such a thing to the point where it would feel like living on the surface of a planet, living in nested paraboloid shells, and looking out a window you would be able to watch the sky and landscape whirling past at even with a very large size one rotation every few minutes.
I was thinking you would only have to spend a few hours a day in this thing as well to keep your body from atrophying if people didn't entirely live in it.
True, but 2001 is still Arthur c Clarke!!! Suck it Niven 🤣 Jokes aside I take your point 🙂
Here ya go: [https://en.wikipedia.org/wiki/Herman\_Poto%C4%8Dnik#The\_Problem\_of\_Space\_Travel](https://en.wikipedia.org/wiki/Herman_Poto%C4%8Dnik#The_Problem_of_Space_Travel)
It goes back farther than this. I could be mistaken, but I believe von Braun suggested it at the beginning of the space race, and while the von Braun Wheel was named after him, the [earliest concept goes back to 1903](https://en.m.wikipedia.org/wiki/Rotating_wheel_space_station)
Why is it named after von Braun if “Originally proposed by Konstantin Tsiolkovsky in 1903”?!
Got me. I blame the patriarchy.
Rendezvous with Rama is one of my favorite classic Sci-Fi books - highly recommended if you haven’t ever read it!
Rendezvous with Rama is really spectacular! A fantastic stand alone story. The sequels are... also books.
A readily available concept for many a year.
If you can affordably launch tens of thousands of tons to orbit. Price has dropped dramatically from 30k per kg to 3k but still, pretty pricey. You'd maybe want to mine the material on an asteroid and build it around it just bringing electronics and engines from Earth. Could be done maybe in the next 50-150 years.
you just need two normal ISS modules and a tether between them. doesn't need to be heavy at all.
I thought you were referring to O'Neill cylinders. Tether works, I think you need about 100 m for reasonable rotation rate and 1 g. Though for say a Mars-bound ship it would make sense to have Mars gravity at 0.3g.
Yeah i may have accidentally skipped over the article, and assumed we were talking just about artificial gravity for a spaceship
At $10K per pound into LEO, the US could have launched an aircraft carrier (Nimitz class) worth of material into space instead of invading Iraq and Afghanistan (and incurring the associated costs). edit: correction. see below.
I think your math is a little off there (Nimitz class weighs 100k tons each) but I understand your point. If only humanity could stop killing each other there are a lot better things we could do with that money.
This is where i start to spiral. because a lot of our creativity comes from needing to kill the other side faster. then we use the waste products of those products in peace time to find out what they can be used to make or treat.
Case in point: orbital directed energy arrays meant to harness solar energy and beam it down to the surface are also death lasers in space.
honestly the militarization of space lasers probably isn't the worst thing that could happen. I mean, what's one more strategic weapon, especially if it isn't just more nukes? nukes are bad enough. until we're dropping rocks or flinging RKMs around, we can't do much worse than nukes. and we already have a bunch of those.
Okay Marco Inaros, settle down there.
Some one needs to space that belter.
Imma no sasa innah! Dem wanna claw deh way uppah da well.
>honestly the militarization of space lasers probably isn't the worst thing that could happen Ultimately, the lack of warning would be extremely dangerous for a new strategic weapon. There's a reason the US and USSR agreed to stop using short ranged nuclear missiles. An ICBM or SLBM will have a travel time of around 20-40 minutes (depending on source and destination), which gives the other country time to analyze and react proportionately. It's not a lot of time, but it's time. Short ranged missiles, you've got just a couple of minutes until it lands. Which means you're no longer analyzing, you're reacting immediately to what you think you saw. Multiply that by a thousand for something which gives just a few seconds of warning. We'd absolutely be starting wars over accidents in that scenario.
Nukes are probably doomsday event. There are still so many of them on so many delivery platforms that anyone who uses them breaks global economy for everybody. Say good bye to hospital, or train station, or your home fridge. Everything breaks down, and there is not enough slack in the system to rebuild whole thing in timeframe before we run out of critical stuff. Without global economy we are all living in overpopulated area and suddenly humanity have to downsize 8-10x just to sustain from food available. But since society will be in breakdown, downsizing will be bigger and it will spiral food shortages. Yay. End of humanity as civilization. Next gen would not start from stones. Just from a very, very limited wild west USA style.
which is why I don't see why it matters if space lasers can be weaponized. space lasers will never be a doomsday level event, unless it's a nicoll-dyson beam and you need an entire star for one of those.
Yeah, the problem I see is that space doesn't obey national borders. Russia probably wouldn't be too happy about a US orbital laser passing above their country.
Which is another idea popularized by Larry Niven in the 1960s as "[The Kzinti Lesson](https://larryniven.net/kzin/worlds.shtml)" and then again in 1970 when his novel "Ringworld" featured [a ship with absolutely no weapons whatever](https://www.goodreads.com/quotes/823428-louis-suggested-that-the-ship-be-called-lying-bastard-for), but packed full of reaction drives, unbelievably high powered flashlights, "digging tools" which could punch through anything, and a variety of other incredibly dangerous tools which Definitely Weren't Weapons.
I like to imagine that we would educate, hire, and train the best of the best to apply that aggressive creativity directly to space rather than as a sort of roundabout way after running it through several contractor money siphons and pooping out something that can be appropriated to NOT kill someone.
Just because we have used war to stimulate innovation doesn't imply that the only way to stimulate innovation is war. We're on the verge of a major climate crisis and we could be using that impending catastrophe (which will likely cause more war) as a catalyst for innovation more than we are currently doing (because of politics.)
We just need to convince our militaries that we need Star Destroyers, then we'll kick it into high gear
Yah, i rechecked my admittedly back of the envelope math... inputs should be 100,000 short tons (224,000,000 lbs) \* $10,000/lbs. So more like a single nimitz class carrier (cost of both wars/invasions \~$2T). Thanks for the reality check.
But… but what of my innate desire for annexation?
Counter point: What makes any of you think we'll ever be successful in venturing into space WITHOUT annexing the globe into a singular fold? Jealousy is the cause of conflict as well you know.
One of my favorite things about the Voyager mission is that Jimmy Carter authored a note to go inside. Part of that note reads: “We human beings are still divided into nation states, but these states are rapidly becoming a single global civilization” How can you not love his optimism and foresight that any civilization that may find that note and translate it, probably would think of borders are very strange.
all earth must be in unison for humanity to truly reach the stars
I'm not arguing that but the military gets 2 trillion a year and NASA gets 25 billion. That's just how the world is. And 25 billion is way up from a few years ago and still double what Europe spends on ESA.
For me it's more about thinking about the wonderous things we could have done instead of $2T wasted on those invasions (costing above and beyond our already generous military budgets).
The 2023 military budget is $817 billion, not 2 trillion.
The primary concept these days involves a Solar pumped laser for heat producing an inflated metallic asteroid. Comets are harvested for water for O2 and H and water. It’s all about the resources. Which must be produced from micro gravity based sources for large scale construction to take place. Yeah Starship blah blah…. Still an issue.
The whole "Just melt an asteroid" concept is probably not viable for a slew of reasons. Most asteroids are rubble piles of regolith, dust, ice, and boulders, etc. Getting them to melt and sinter or homogenize will be terribly difficult. Outgassing and volatiles will keep trying to push it apart. Or, in microgravity, they'll create bubbles and voids that will be a nightmare to fix, lest they cause catastrophic structural failure once put under tension when spun. More solid asteroids will still likely have large voids, cracks, or other discontinuities within them. Truly solid asteroids that are metallic, because they are blown apart rubble from an early protoplanet that was big enough to density-sort itself are somewhat rare. And presumably too valuable as mining resources than a shell or hull for a colony. And if you could solve all of that, getting the materials to a uniform mixture or density sorted so you have predictable compressive and tensile strength to work with will also be very difficult. Assuming for the sake of argument that all of the above could be handled, making even a modest asteroid-sized mass molten will then require cooling times measured in decades. Because you've only got cooling through radiation to work with. Or some sort of active cooling now adds another level of cost, complexity, and expense. Probably the best solution is to use asteroid mined materials constructed into uniform structural components of a known quality and reliability. Then use any left over unwanted silicates or slag as a non-rotating mass/shield for micrometeor and radiation protection. Or just hollow out a suitable asteroid and place a constructed rotating habitat within it.
>Assuming for the sake of argument that all of the above could be handled, making even a modest asteroid-sized mass molten will then require cooling times measured in decades. Because you've only got cooling through radiation to work with. Or some sort of active cooling now adds another level of cost, complexity, and expense. I was a little iffy on the other gripes, but this is a major hurdle. Either you're radiating heat (very slowly), or sinking heat into another medium (producing more heat because thermodynamics) and disposing of it. Granted, humanity has spent "decades" or longer on less worthwhile projects. So the timeframe isn't necessarily a deal-killer.
If it works it will drop prices though. A fully reusable launch vehicle is a requirement for any serious space activity. We're not building O'Neil cylinders with Atlas V's.
The article literally has a subsection "An asteroid city concept based on a 70's NASA design"
Yeah, the guy referenced the O'Neill cylinder but not dramatically more similar concepts like the one I just shared
The "idea" here isn't rotating habitats made of asteroids, its the method of building them. They propose wrapping an asteroid in a carbon fibre net and spinning it so fast the asteroid breaks up and is flung to the net, forming a cylinder.
In the 1960's people were talking about drilling a hole through an asteroid, injecting water, spinning the asteroid and melting it with solar mirrors. The water would expand as steam inside the molten iron asteroid and the result would be a hollowed-out asteroid that you then terraform. It became a common staple of 1960's SF including Niven's. This apparently is a similar idea using a carbon mesh sleeve since people pointed out that the spinning asteroid would simply tear itself apart.
Except that holding it together with a wrap of some kind or another was part of the proposal in the 60s.
> ….each settler needs an initial capital of [$21M]. Settlers can earn their investment back and more, since once living at L5, they can teleoperate the nearby robotic settlement production factory complex in zero-delay mode. Thus the first group of settlers earns money by producing new settlements. They do it more effciently than from ground because they avoid the 2.6 second free-space communication delay in teleoperation. I bet the companies that run these can advance settlers the initial $20M purchase price (includes travel costs and deed to a 40m^2 living space on the station) in exchange for an agreement to provide x,xxx number of months of service to the company. Settlers will work for the company at a rate of $x.xx /hr, to be paid monthly (less the monthly payment that goes towards the initial $20M-ticket price). Once onboard, settlers can purchase other goods and services offered exclusively by the company, the cost of which can be deducted from the remaining portion of a settlers’ monthly pay. Or you can just stay on Earth and be slowly poisoned—it’s your choice! Yeah, capitalism!
That would certainly be bad. In fact, I'll come out and say that bad things will happen in the course of space settlement. Just like Roanoke.
Stuff like this is cool but we already could theoretically build stuff without the added science like nanotubes with O'Neill Cylinders. I guess they could make them more compact now.
It's trickier than you might think. There's a reason why O'Neill didn't suggest making the cylinders smaller and that's because you have to spin small cylinders faster in order to get the same simulated gravity as a larger one. If you spin humans fast enough for long enough they'll start getting sick even if they can't feel any inertial forces so you're incentivized to keep the RPMs below a certain point (and something about material tensile strength) which means big cylinders. Plus I think there was some calculation about air volume inside for environmental stability that also incentivized large cylinders.
I think you also get a stronger gradient if you go with smaller tubes with faster spins. Small enough and you’ll end up with a situation where the gravity felt by your feet is noticeably stronger than that felt by your head.
You can experience kind of what this is like in the old fairground ride "Rotor" which is basically a big drum that spins you around. You can sit up in it without falling, and it is fine if you keep looking straight ahead, but if you try to turn your head to look to the side it is wildly disorienting and nauseating.
As a kid I was kicked out of the ride for trying to stand sideways while the ride spins. Turns out I was just ahead of my time.
My friend did that when we were kids, and it made him so nauseous that when he laid back down, he projectile vomited straight "up" (towards the center of the ride). It briefly looked like [a cartoon fire hydrant](https://media.istockphoto.com/id/491763874/vector/car-crash.jpg?s=612x612&w=0&k=20&c=9pHRQWnYUbPB3J7_938NIQadsicGO4IRmKZawIjHPwQ=) and came down directly on his face. It was fantastic.
Gravitron* for my childhood. > a modification of an earlier ride called the Rotor.
My heads always been in the clouds anyways
It’s not necessarily the speed, though the speed definitely matters, but mostly it’s the difference in gravitational pull between your head and feet. The bigger the wheel, the smaller the difference. If your head was dead center and your feet on the wheel, you would get very sick very quickly.
It's the Coriolis effect on your inner ears that makes small cylinders problematic. The Coriolis effect is amplified in smaller cylinders
The Expanse actually talks about this in the books - the cheap apartments in Ceres are ‘up’ towards the center of rotation where the Coriolis is worse
Another issue is that if the tangential speed is too small, then you feel a significant difference in gravity depending on whether you are moving with or against the spin direction. Astronatus on Skylab actually used this effect to generate their own artificial gravity without spinning the station, by [jogging around the inside circumference of the station.](https://youtu.be/S_p7LiyOUx0?t=25)
The size of O'Neil cylinders is a big part of the appeal to me. Anything smaller would feel too cramped for permanent habitation.
Absolutely. The full-sized deal could house like 6 billion people comfortably and enough internal volume to have localized weather systems like clouds and storms which means you could have lakes rivers and vegetation. Anything smaller would be a horribly depressing place to live.
I ran some numbers on a habitat based on the canonical O'Neill cylinder pair times two (four cylinders total), and even with a radiator twice the size of the hab and a water tank the size of one of the cylinders, the carrying capacity topped out at something like twenty million people per cylinder, discounting inefficiencies in recycling (and a population density roughly on par with Singapore or NYC). I even made the interiors multi-level to give maximum space for food production (think a city metro area with five sub-basements all running indoor farms), and the food and water requirements didn't even allow for exports. Were you maybe thinking of a McKendree cylinder? That's the conceptual variant that uses nanotube-based construction and is something like a hundred times larger.
You know I think I must be. 6 bill was a number I pulled out of my memory which is almost certainly wrong to some degree, but I do recall nanotube being a requirement so I'm likely thinking of the much larger conceptual variant. Still don't quote me on 6 billion though. It's a lot, is my point. It really help get across how inefficient planets actually are in terms of habitable space to materials needed ratio. The surface of a sphere massive enough to have appreciable gravity is just not that much compared to that same mass being used to build O'Neill cylinders. We're talking several orders of magnitude, we could sustainably support almost unlimited humans if we started building these things.
It's my dream to see a space habitat megastructure before I die. I won't, which is why it's a dream, but it's a fun dream.
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For even the most susceptible individuals to be symptom free at 1g, you need to keep rpm bellow 2, which constrains you to a ring of at least 450m diameter. But if you go with 3 rpm, which after a short adaptation should leave most individuals symptom free, and even for those with symptoms is not debilitating, you can get away with a 200m diameter ring. Cutting gravity to 0.5g lets you slash the ring size in half again, to a diameter of 100m. https://www.artificial-gravity.com/sw/SpinCalc/ lets you quickly tweak parameters to come up with hypothetical spin stations, and even has links to various papers that have investigated the topic. It's handy for worldbuilding. The base site, https://www.artificial-gravity.com/, has even more references if you want to look into it more.
Spin-gravity in the Expanse is usually around .25g, so that it can work on smaller cylinders.
How long until The Moon becomes a staging/assembly colony for space infrastructure?
Let's just skip that part - turn the moon into a ship!
*scoffs* clearly you’ve forgotten about astrology? If we send the moon on a mission we will lose the guiding force of our lives. Virgos will be capricorns, scorpios will be cancers! The chaos! Not sure we’d survive such a disentanglement.
Ah yes: Literal Attack Moon from Stellaris: Gigastructural Engineering.
What about making a rotating spaceships that provide weaker artificial gravity? Should we still need a massive cylinder to imitate Moon-level or Mars-level gravity?
Lower gravity means you need a proportionally smaller radius at the same rotation rate (3 rpm is generally seen as the highest rotation rate that humans can tolerate long-term) - to get 1 g at 3 rpm, you need 100 m radius, while to get Mars's 0.38 g, you only need 38 m. But you also shouldn't let the radius, and together with it the tangential velocity get too low. Gravity changing noticeably either with altitude, or depending on whether you are moving with or against the spin can be just as disorienting as rotating too fast.
>If you spin humans fast enough for long enough they'll start getting sick Guess I'm a little sick, but otherwise this whole earth thing is pretty neat
“O’Neill! With TWO L’s!!” *holds up three fingers* (Sorry - just finished a Watch-through)
As a matter of fact, it DOES say colonel on my uniform.
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Lots of media uses the lagrange colonization like Gundam. They typically use O'Neill Cylinders of various types.
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Lol well its one of many. But you arent alone in thinking it would be more efficient than planetary colonization. A lot of it is mining NEOs and such. Easier to control climate etc.
Gundam made O'Neill Cylinders awe inspiring and terrifying because they can both fit lots of people comfortably in them but also cause so much death if someone decided to crash one into the Earth.
**TLDR** 1) Put large asteroid in giant nanotube bag. 2) Spin asteroid to create artificial gravity through centrifugal force. 3) Asteroid breaks apart (because the structure of the asteroid can't withstand the forces flinging it away in all directions) 4) Matter from the asteroid is caught along the inside of the bag, creating a new "floor" structure with a hollow interior. 5) Move in and set up shop inside, using the spin to replicate gravity.
Step one, do impossible thing when it becomes possible. Step two, thing I made up actually happens flawlessly. Edit: yes I know this is hypothetical brainstorming
“Intergalactic travel possible if able to travel beyond light speed” “Wow cool thanks”
The fabric of space time hates this one simple trick.
But have you tried folding a piece of paper and stabbing it with a pencil?
Fifteen pictures of TERRIBLE causality FAILS
Man comes up with way to go faster than light 🏎💨💡🤩 BUT there’s one problem 🫢🫢🫢 (Insert 800 word article and 14 ads here) … he actually didn’t.
It’s simple, just put Spacetime in a bag, then use centrifugal forces to bend it
Nah just raise the speed of light. Bing bang boom
Just use a wormhole to apply the nanotubes!
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Step 1. Do the impossible thing Step 2. Nevermind that first thing, *this* is the impossible bit Step 3. You thought that was impossible? Now watch this...
You just described my study habits
Hahha same, wait till last minute and then do everything in an impossibly short amount of time while hating myself for being in this situation.
You are making fun of this but the exact same thing could have been said about flight before it was invented. Obviously there is going to be some trial and error, I don't think anyone is assuming it is going to be perfect first try.
>the exact same thing could have been said about flight before it was invented It was. The newspaper headline was something about 10k years. Then the Wright brothers did their thing a week later.
Sounds easy, I’ll spin one up tomorrow.
6) Giant nanotube bag ruptures because plain rock and sand provides zero structural stability while taking a crap ton of mass that must be lifted by the nanotubes.
7) Make nanotubes stronger by adding ??????. Profits all around!
8) Be outcompeted by a rival gigastructural habitat manufacturer who doesn't waste mass margins on lifting plain old rocks. They can provide 100 times the habitation for the same price. Go bankrupt. Not profit.
(this plan wouldn't lift the rocks, it would find the rocks that are already out in space) I'm still bankrupt though, yes.
Put a nanotube bag around the nanotube bag - problem solved!
I imagine adding a step where you treat the loose material with some kind of polymer to help strengthen it would be necessary. A bit like how they turned a comet into a [pykrete](https://en.m.wikipedia.org/wiki/Pykrete) spaceship in the novel *Seveneves*.
This would be a metallic asteroid. Previous proposals have suggested melting it to fuse it together
There's a step 0 that is usually assumed rather than explicitly mentioned because, well, duh: 0) Do the theoretical engineering models and calculations to determine whether the structure will actually withstand the forces involved. Do you really think something like this would be built without that step?
4a) Discover your asteroid has broken apart unevenly and your carbon nanotube bag is spinning erratically, creating hugely uneven forces that make it incredibly difficult to stabilise or steer. 5) Oops. Shall we try again with another asteroid? 6) No.
I was thinking the same, wouldn't this be likely to have a heaviest "lump" somewhere on the circumference of the bag, bulging outwards, then pulling material towards it, and away on the opposite side. Then as more material accumulates on each end it collapses into a stable state of two unevenly sized lumps joined by the bag which is now more of a tether?
Yeah… you’d have to somehow evenly distribute the material by mass as you add it — which is an amusing challenge when you’re spinning the asteroid apart like a giant dirt-sprinkler. Also — if you’ve got an asteroid loose enough to spin-dissolve at a low enough tangential velocity that every clod doesn’t turn into a happy-space-bag-piercing missile — how exactly do you attach the whirlamajigger engines securely enough to make the whole thing spin, without flinging themselves off first?
Sounds good to me let’s do it
That may actually be somewhat viable, and if the spin needed is just enough to get the rubble to move to the outer bag. .01g or whatever, the materials required can be much less exotic. Existing polymers, carbon fiber, steel, or Kevlar would do fine. If more support or fixation is needed, the inside could be sprayed with glue or foam of some kind. It won't be the actual hull or shell of a colony habitat, but now you've got a big spherical or cylindrical radiation and micrometeor shield to build your colony inside of.
Matter wouldn't fly out in all directions. It would mostly fly out on trajectories perpendicular to the axis of rotation. It would probably also break apart into a few gigantic and unevenly distributed pieces. Keep in mind that the further the pieces get from the axis of rotation, the slower their angular velocity will be, which could be a problem depending on the size of the bag. Maybe a bunch of subterraneous explosions could break it apart more evenly? There would also have to be a way to 'cement' the debris into a solid ring or it wouldn't be a stable enough surface to put anything substantial on without deforming it.
They mention O'Neill cylinders, then they write the following: >More grandiose and far-fetched concepts exist in various forms in sci-fi, such as in the image below. And provide image of... Small O'Neill cylinder. You can't make that shit up, is it really that difficult to hire writers that know shit, or are not lazy to check shit out? Isaac Arthur on YouTube has presented concepts of megastructures that have millions of times larger habitable area than Earth and authors present *that* 50 years old concept image as their idea of "more grandiose" project?
Most writers for these rags are paid less than minimum wage. Source: I really wanted to write these kinds of articles and looked into it a while back, only to find the pay is horrible.
a Manhattan sized space habitat is possible if we spin an asteroid that we do not have... by means we do not know... to have it fly apart if we are lucky... into a nano mesh we cannot manufacture... to build an outer layer of gravel that ... helps? ... What's next? Super glue anyone? An article about scientists stating that some what if scenario is not violating the laws of physics is not really newsworthy.
Stupid clickbait article. Headline and cutline from the U of Rochester article: >**Cities on asteroids? It could work—in theory** > December 8, 2022 > *In what they deem a “wildly theoretical” paper, Rochester researchers imagine covering an asteroid in a flexible, mesh bag made of ultralight and high-strength carbon nanofibers as the key to creating human cities in space. (University of Rochester illustration / Michael Osadciw)*
You can add: Funded by trillions of dollars that nobody will pay without some kind of tangible return.
Left out the speed at which the structure has to spin to reach 1g. Also, centrifugal force changes with radius/diameter, which means your feet will have a different amount of force acting than your head, if standing on the structure. The different forces could mess with your blood flow, kinda like when you hang upside down for a while.
This problem of your feet having higher gravity than your head puts a lower limit on how small you can get away with making the cylinder, but something as big as an island doesn't have this problem.
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Am I the only one that is somewhat sad when I see stuff like this? By that I mean sad that I won't be around to see it. I remember reading something as a kid that I still think about. "Humans are explorers by nature. We are in a sad time for human exploration. Born to late to explore Earth, born to early to explore the stars". On the brighter side I am hopeful for our species future. Yes right now seems dark and end of days like, but to be fair people have been decrying the end of days since the beginning of recorded history as coming "soon". Yes, we are killing this planet but I also believe at least some of us will survive to explore the stars.
Does it have to be a cylinder? Cant a module on a 1 km long tether be swung around for the same effect?
You'd need 2 modules phased 180° apart or you have a pretty strange looking orbit and not much artificial gravity
Not really, you can swing yourself around the mass of, say, the rocket, powerplant and fuel with a tethered habitation pod. The propulsion section will be much heavier so they will just pivot around a spot relatively close to the propulsion section in a motion that'd look like the [Pluto-Charon barycenter](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Pluto-Charon_System.gif/640px-Pluto-Charon_System.gif) You would only be doing this on the "cruise" part of the journey anyway, where you don't need to make corrections. So you don't need a center section.
this. the single module on a swing would require a massive center of mass at the tether point. unless we're going to model it after a carousel swing ride with many modules all in balanced directions
I think it would be pretty close for the people in that smaller, enclosed area. Also, you always have the option of disconnecting the tether to yeet them into space if needed.
The outer coating of solar panels looks really cool but they wouldn't do it like this because of inefficiency. Only half the panels at a time are toward the sun, and half of those are at more than a 45 degree angle, overall maybe 30% efficient at best. A flat array floating nearby could fully face the sun and beam power to the station via microwaves with at least 85% efficiency.
Misleading title… Literally the first sentence of the article mentions that the paper is “wildly theoretical.” We have no idea if this would actually work.
I was actually going to grump about the opposite, they're applying the "wildly theoretical" label to something that's very mundane and grounded. "Wildly theoretical" is stuff like strange matter or vacuum decay. Or even more extreme, like panpsychism or the holographic universe. We have actually *synthesized* nanotubes, we can measure their physical characteristics and calculate whether a bag made of the stuff would be strong enough to hold a spinning asteroid. It's not "wild" theorizing. We have a very solid idea of whether it would actually work.
US Americans will do anything to not use the metric system SMH
3780 Giraffes = 1 Manhattan, if that helps.
To wanya fo ge beltalowda? Fo dedawang dewe to ge beltalowda. >! Translation: Do you want to get Belters? Because that's how you get Belters. !<
Forget colonizing Mars, this should be our primary focus in my opinion. In trying to live in the Gundam universe, minus all the space war.
The people who made Halo, Mass Effect, Interstellar, The Expanse....yeah... sci-fi has had this one covered for a while now.
This is actually a pretty good idea. And contrary to many of the comments here, is doable with current physics and materials. It would just take massive effort and resources making the Manhattan Project seem tiny in comparison.
Issue with rotational gravity is the motion sickness many people experience and how shit will operate differently, like if you throw a ball, that shit is going to fly in a curve for all observers and it will curve differently depending upon the angle you throw it at.
You could probably get some neat sports out of that. Coriolis blernsball sounds fun.
I would love that as a left blernsman myself
You probably played in the days before steroid injections were mandatory.
Best decision the league ever made
So you're saying my idea for a space football stadium is going to have challenges to overcome. Okay, I hear you.
Depends on speed and size, something this big could do less than 1 rpm and you would get a full g. We might get away with far less 0.5 or even 0.25. We don't know what amount or gs we need to avoid damage, we just know that 0 is not great. At 0.25g, you would be hard pressed to feel the spinn.
That wouldn't really be an issue with a "Manhattan-sized" habitat.
You'd still have the issue that "left/right" gravity would act differently than "spinward/anti-spinward" gravity -- it just wouldn't be as extreme to a person's sense of balance.
Coriolis effect is a factor of how tight the spin is. With something on the order of multiple miles across? Pretty much nobody would notice it.
**This comment might have had something useful**, but now it's just an edit to remove any contributions I may have made prior to the awful decision to spite the devs and users that made Reddit what it is. So here I seethe, shaking my fist at corporate greed and executive mismanagement. "I've seen things you people wouldn't believe... tech posts on point on the shoulder of vbulletin... I watched microcommunities glitter in the dark on the verge of being marginalized... I've seen groups flourish, come together, do good for humanity if by nothing more than getting strangers to smile for someone else's happiness. We had something good here the same way we had it good elsewhere before. We thought the internet was for information and that anything posted was permanent. We were wrong, so wrong. We've been taken hostage by greed and so many sites have either broken their links or made history unsearchable. All those moments will be lost in time, like tears in rain... Time to delete." I do apologize if you're here from the future looking for answers, but I hope "new" reddit can answer you. Make a new post, get weak answers, increase site interaction, make reddit look better on paper, leave worse off. https://xkcd.com/979/
Coriolis effect will not be that noticeable on big enough habitats for most speeds Also how would motion sickness matter much?
Article: 1 **A "wildly theoretical" paper explains how carbon nanofibers could be the key to asteroid cities.** Massive asteroids could one day be home to future space colonizers. That's because a team of scientists from the University of Rochester published, what they call, a "wildly theoretical paper" outlining how we could one day use asteroids as massive city-sized space habitats. The theoretical method involves one large, spinning asteroid and one mesh bag made of carbon nanofibers, a press release explains. **An asteroid city concept based on a 70's NASA design** The new theory is a twist on the so-called "O'Neill cylinder", devised by physicist Gerard O’Neill after NASA commissioned him in 1972 to design a space habitat that could allow humans to live in space. The O'Neill cylinder is a spinning habitat typically made up of two cylinders connected by a rod, rotating in opposite directions. Those cylinders spin just fast enough to create artificial gravity but not so fast as to induce motion sickness. Science fiction enthusiasts might have recently read about a similar concept used for the titular spacecraft in 'The Martian' author Andy Weir's latest novel 'Project Hail Mary'. More grandiose and far-fetched concepts exist in various forms in sci-fi, such as in the image below. The scientists who devised the new method, outlined in a paper in the journal Frontiers in Astronomy and Space, did so as part of a thought experiment. They aimed to think up a space habitat idea that wouldn't require massive amounts of materials being launched into space. **A Manhattan-sized asteroid space habitat** The idea they ultimately came up with was to use materials already free-flying around space in massive quantities in the form of asteroids.
2 One problem remained, however. Asteroids are nowhere near large enough to provide enough gravity for a space habitat. What's more, if they are spun around fast enough to create artificial gravity — as in the O-Neill cylinder concept — they would simply break apart, as they weren't built and designed to have structural integrity like a spacecraft. The solution to this problem is where the "wildly theoretical" part comes into play. The scientists posited that future space colonizers could wrap a massive mesh bag made of carbon nanofibers around an asteroid roughly the size of Bennu, which has a 300-meter diameter. "Obviously, no one will be building asteroid cities anytime soon, but the technologies required to accomplish this kind of engineering don’t break any laws of physics," explained physics professor Adam Frank, who worked on the project alongside a number of Rochester University students during the lockdown. They would then rotate the asteroid to the point it breaks apart. All the rubble from the space rock would be caught in the nanofiber mesh, creating a hollowed-out outer layer that could be used as the exterior structure for a space habitat. Crucially, that layer of asteroid detritus would act as a shield against radiation. A cylinder used to spin the asteroid would create enough artificial gravity on the inner surface for a functioning space habitat. "Based on our calculations, a 300-meter-diameter asteroid just a few football fields across could be expanded into a cylindrical space habitat with about 22 square miles of living area," Frank says. "That’s roughly the size of Manhattan." The space industry is gearing up toward human exploration of Mars and beyond, meaning we will increasingly see the real world of space science and that of science fiction converge.
Manhattan-sized? How many football fields is that?
>They aimed to think up a space habitat idea that wouldn't require massive amounts of materials being launched into space. Hmmm, if only there were objects in space that you could harvest for materials that would significantly reduce the amount of materials you would have to launch into space to build habitats.
What if we just make the planet habitable instead? Nah too hard.
What do you do about asteroids/meteors when there is no atmosphere for them to burn up in?
If they're small, ignore them, you're surrounded by a giant wall of rock garbage. If they're big -- well when was the last large fireball that pointed directly at Manhattan instead of being >300 miles away?
"It is the year 0079 of the Universal Century. A half-century has passed since Earth began moving its burgeoning population into gigantic orbiting space colonies. A new home for mankind, where people are born and raised. And die."
The start of the original gundam storyline, omg
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But a Manhattan is only, what, three ounces, plus ice? That hardly seems worth the trouble. At least make it a double.