Spinning Asteroids To Make Space Stations 

also i guess all that rock is a nice protection against that nasty space radiation, in my opinion that's the only advantage of digging a hole in an asteroid instead of building something on the surface anyway.

frischer bärlauch speaking of those nasty little solar rays i wonder if it's possible to put something near Ceres to block out the rads, like a nasa scientist (i believe it was) suggested recently. Then you could build habs on the surface. Maybe put up a nice little space elevator.

+Daniel Carter Well, why would you build a large space habitat like that, to shield workers from radiation and micrometeorite and provide them with artificial gravity while they mine the asteroid but wait, if you have to mine the asteroid first before building the habitat then how will you house them while mining and once it's mined, why would you continue to have to house miners? It would make far more sense to build a smaller habitat either floating nearby or a small centrifuge on or just below the surface rather than turn the entire asteroid into a habitat.

John Wang i never said a hollowed out asteroid with a cylindrical city made sense, I'm just saying that's how i always figured it was done. Personally I'd but a magnet in orbit to block stellar radiation and build bowl shaped habs on the surface and spin them to have artificial gravity. And you'd want a permanent base on Ceres because there aren't any satillites, it's rather small, lots of fuel, and it's larger and more circular than a lot of other bodied you could consider.

John Wang i don't see the point in a habitate on a planet or a dwarf planet or whatever if there is no atmosphere, you might as well sit in a tin can in orbit. However, I wonder how much radiation would actually be absorbed by an asteroid if it has such a dusty consistency

They're called primaries. Gets popcorn

this made me happy.

I have had a few of those myself

Progressive break up!? No, please don't go Flo!

But the “ make up sex” during the process is great.

I've never had time to read the books, but the TV show titles make it look like that. I know there was at least one religious group who believed that instead of living on the surface of a sphere, we in fact lived on the interior of a sphere en.wikipedia.org/wiki/Koreshanity They had to come up with some rather complicated refraction mechanics to make the sun more correctly in the sky. If the GOT world were like this it would need something similar to create the sunrises and sunsets in the show.

Speaking of shell worlds, have you guys had the chance of reading Iain Banks' "Matter" ?

He did a few videos in ksp ages ago, before his channel blew up

gotta get Preston Jacobs in here

Universe Sandbox actually has Westeros orbiting it's 2 suns as an imbedded feature so you can get all the stats on it.

His kid is probably like "my dad is boring he likes maths but he has cool computer games"

You can't possibly consider a guy who makes you do homeworks and eat your broccoli cool. Not at his age. The understanding of Scott's coolness will come later.

Almost certainly not

*Kids, he has two. And I think they trhink he's pretty cool.

that is actually a good question

There's also visual of a bird literally floating after flapping its wings once or twice, so the gravity is VERY low

There is a scene of a character pour a drink from a jug. The stream shows exagerated effects of corriolis. I think this would indicate a very small radius station spun at high rpm. I seem to recall from the books too that well-to-do on Ceres could afford apartments on the edge of the station where the spin gravity would be highest and thus cause fewer health complications. Then there were the unspecified, expensive medical interventions that Belters could undergo to mitigate the health effects of low G, a rubbing point between Miller whose parents did pay for the interventions and other Belters. It set Miller apart as a privileged rich boy.

I can't remember if they specify it in the TV show, but in the book it's stated that Ceres is spun up to about 0.3 g, which is close to Martian gravity. The slums of Ceres are toward the "ends" and are closer to the axis of rotation so the coriolis effect is more pronounced. Most stations and asteroids that use spin for "gravity" have settled on something in the range of 0.3 g, however there are a lot of habitats on moons like Luna, Ganymede, Titan, Io, and Triton that just have whatever gravity the moon naturally has, and there are a few smaller asteroids like Pallas which were never spun up because they couldn't take the stress and so have almost no gravity at all.

They mention in the book that the outer layers have 0.3g The more you go inwards, the less gravity you have (thus poor people tend to live inward)

@@ericjamieson Ceres natural gravity is already 0.27g

You sure, you wanna mess with this stuff? It gets out of control quickly...

FirstPersonStranger protomolecules, son

Major Dakka Coulda' gone pro if I hadn't joined the Navy!

Protomagicule

It would also protect against small meteors and micro meteorites

I've been much more of an advocate for the O'Neil cylinder inside the asteroid idea. Though... you do have to have some strong magnetic bearings to ensure your cylinder doesn't precess out of center.

Just the idea I had some years ago. I mean he's right questioning the need to spin up an asteroid. Is there any model available of such a design?

Found this after independently duplicating your comment. Precession is prevented by building counter-rotating structures attached to the habitat. They have equal but opposite angular momentum, so no precession.

Couldn't the whole structure just torque off the asteroid itself? The enormous mass of the asteroid would serve as the counter rotating structure to the relatively tiny mass of an air-filled space station. If you place the station at the centre the effect of the asteroid would be barely detectable.

I expect asteroids are going to be predominantly loosely packed rubble piles. Using the intrinsic rock as a shield will probably be about as effective as covering a bunker with packing peanuts. I'm betting on a bit more structure from a combination of engineered trusses and bails of loosely consolidated raw asteroid material. Still going with an un-spun shield made up of bailed rocks and water tanks then connected to a spun habitat inside with magnetic bearings. Asteroids like Ceres or Eros would ironically be too big, carrying with them small but noticeable gravity fields. A habitat built inside a void would get the vast majority of its gravity from its own spin but then have the asteroid's gravity overlaid leaving inhabitants with a gently rocking environment. Everyone's soup pots would be self-stirring but furniture and dinnerware would be self-relocating. An engineered external shield would be uniform in mass netting out to zero gravitational effect. A shield wouldn't need to be especially overwhelming, a dozen meters thick combination of rock and water tanks would put up far more protection against micrometeorites and radiation than the Earth's atmosphere. Habitats inside asteroid voids would not be ameniable to relocation. If Eros station ever got bored and collectively wanted to to experience the thrills of Mercury or hanker for a jaunt to Pluto it would mean thrusting all 34km by 11km by 11 km (6.7e15 kg) of Eros. A habitat with engineered shield would likely mass "only" around 1e12 kg, a featherweight compared to Eros.

Depends on the composition. Plus nobody said that you can't reinforce or stabilize faults in an asteroid. The stations in ED all have massive struts holding them together from the inside.

+jodomo which is great and all, but if you have to fill the fucking thing with steel anyway why not just make the whole thing artificially?

Shell of dead rock to provide shelter (rock is great insulation from radiation and weapons), steel inside to give structure.

answer is fairly easy....mass is the issue,,,soo just hollow the thing out morons. remove like 4/5ths the mass....in fact they did on the show, they extracted all the water .

I was gonna post this too. Isaac Arthur is SO good and more of the space-community should watch his videos.

+Herbstein Gotta spread the good word whenever possible :P

Honestly I avoid watching his content because most of what he does I might do in the future and don't want to be accused of plagiarism.

Understandable. This just means we have more superb content to look forward to :D

i saw his channel, he has really nice vids.

it would be alot easier to use a iron asteroid,,,to build a space station. melt it down and build what ya need. or at the very least just hollow it out mostly. like 90% hollow.

@@autopartsmonkey7992 i think asteroids have the advantage for 1 reason, easy radiation shielding, easier than you could get on a space station.

I think the reason for Ceres station being the way it is is because "digging" requires a lot less material than actually building something. Just dig and throw away some part of the asteroid and voila, you suddenly got space you can build a habitat on. The spinning part is to resolve the gravity issue. When you have a basically magic Epstein drive, that's not that hard

Warp Drive - Hyperspace - Wormholes - Transporters...yada, yada, yada. How Many Angels can dance on the head of a Pin? It's not called SciFi=Science Fiction, or SyFy=Science Fantasy for nothing folks!

The Epstein drive should be something close to Hawkins radiations.

@@Fridaey13txhOktober ?

"small pellets"=/="phenomenally efficient". Basically, it's magic.

Or even better, use a Tunnel Boring Machine (TBM, instead of the incredibly labour intensive cut and cover.

Fast train. 473km/10mins 3600km/h but mag lev it maybe

@@jorgepeterbarton Tangential velocity would depend on the radius but nice try at seeming to sound as if you know something. Yes, it would be fast but you are in space and magnetic suspensions is more than sufficient, I would imagine permanent magnets on a Halbach array along the habitat pressure vessel and aluminium coils as the tracks thereby using Lawrence Livermore's Inductrack system as the materials needed are plentiful and there would be no need for cryogenic temperatures, just heat dissipation issues from the aluminium coils but aluminium also makes good heat radiators. Of course, it would be maglev as well as tension cables in the habitat as the habitat could go completely around the "track" hence the mag Lev would not be needed to sustain the entire weight of the structure even when spinning as the tension cables would do that, the magnetic levitation would only be needed to center and guide the structure so no contact is made, and quite frankly, as most of the forces would be in the tension cables anyways, even a mechanical system instead of maglev could be used as again it is only centering and guidance that would be involved and that would be intermittent. A mechanical system would just be more costly and precision manufacturing intensive than just setting up a Halbach array and aluminium coils. We're not talking about the precision supercooled maglev of millimeters of trains on Earth, just preventing a spinning ring from contacting what it's spinning in while in the microgravity of an asteroid. Normally, the habitat pressure ring should not require anything to avoid contacting whatever it's spinning in, it's just that occasionally it would need to be guided away.

it is both

There is a common misunderstanding that asteroids are all the same thing. Also, Manley's projection seems to assume this trick is easier for larger objects. The opposite is true. With a maximum spin rate of 2 RPM, you can get useful gravity with natural materials, like basalt and granite. Nobody is going to try to spin up a slagpile. This is a "straw man" post.

and you could use big mass drivers to spin it up and eject the excess mined material.

but then you still would have to spin up the mined material...that would undermine the whole idea of hollowing it out in the first place...you need to bring out the mined material fia conventional, far more efficient methods...

So what you're saying is hollow out the asteroid and use spacecraft to dump the mined material somewhere, then spin it up using fuel you brought from earth? That doesn't make any sense.

no...i am saying hollow out the asteroid without spinnig it, removing the mined material with, lets say conveyor belts or push it out or give it a little push and let it drift out in microgravity and then, after removing most of the mass of the asteroid spinning it up

and who knows from where you get the fuel, doesn't need to be from earth at a time where you are technologically advanced enough to hollow out an asteroid...could even come from the mined material itself...

The asteroid belt is about as far away from the sun as you can get and still primarily use solar power[1] so maybe? The question is is it worth the time and energy to try something like that or do you build something that you know will work and fly it out there. [1] I know we've sent solar powered probes out farther than that but I'll take a RTG at that distance any day of the week.

I was talking about natural the spin up process, if vaporizing ice might cause the asteroid to spin, but I guess focusing sunlight intentionally onto an icy part of the asteroid would be a very cost effective way to do it assuming you have large, cheap and accurate enough mirrors to do it :) And now that I'm a little bit less tired I can actually calculate the distance at which this can occur naturally: It would be using Stefan Boltzmann's law and some algebra we get: r_asteroid^2 = T_sun^4 * r_sun / T_boil^4 (We got this by calculating when the amount of energy radiated per area of an asteroid being at boiling temperature is the same as the energy received by the suns radiation). Plugging in some numbers that gives us 166 805 431 km or about 1.1 AU, so yes, they are too far out for this to be a thing. However liquid water does still evaporate slowly, so plugging in the freezing temperature of water instead gives us 2 AU. Still not far enough out, but some asteroids could come close to that distance. Still, using mirrors to do this if there's ice on the asteroid would be viable, maybe even a way to move the asteroids :) Then you wouldn't need to transport anything out to the asteroid to move it, you can just shine the "sun death ray" on it in very precise locations. You would need some very large mirrors tho, but that wouldn't be much of a problem, they would be pushed away from the sun slightly but easily compensated for using small thrusters, or you could position the mirrors in such a way that the small distance your pushed doesn't really matter much, eventually you would have to compensate for it tho if you plan on using the mirrors many times to move many asteroids. In practice you would probably still have to send probes to the asteroid to determine it's exact center of mass, where ice is etc etc so you know where to shoot on the asteroid. You might also need to send up mirrors to be able to shine light behind the asteroid. I think Isaac Arthur made a video on this, not sure tho :/

Well, ice still sublimates at very low temperatures, specially in vacuum, so I wouldn't discard this possibility.

If you look at a phase diagram for water you see that you'd have to get above 200 Kelvin at a minimum to get vapor. Plugging that into the previous equation gives us about 3.8 AU, so yes, there are asteroids inside that range within the asteroid belt it seams (the belt between mars at around 1.5 AU and Jupiter at around 5 AU) If you're talking about "stray particles sublimating" such as evaporation experienced here on earth even tho you're not above boiling point, I don't think this would have a very big effect in a crystalline structure such as ice but I could be wrong, I just thought the temperature distribution in the substance thinned off very quickly when you get down to lower and lower temperatures allowing for extremely few atoms to sublimate.

Going further deep in this topic, one photon from the sun has more energy than the hydrogen bonds connecting each molecule in a crystalline ice structure. So I guess exposed ice will sublimate, no matter at what distance from the sun. I think this mechanism is better called ablation than regular sublimation, but... Let's go to the numbers: The hydrogen bond energy in ice is about 4.5 kcal/mol. With 4 bonds in a crystalline structure, this gives an energy of 0.78 eV per molecule. Even a low energetic red photon from the sun, with a wavelength of 780 nm, has an energy of 1.59 eV. Of course some of that energy is transferred as heat to the ice (and I have no idea on how to estimate that), but I believe there's a significant sublimation rate. Maybe enough to spin an asteroid in a couple million years.

Whole new meaning to "grow your own", isn't it? Look up "dyson trees" if you want an example of a wooden (living) space station.

That, sir, is the right answer!

A pair of opposing O'Neil cylinders, inside that lovely rock shielding.

Circular train tracks on the surface, or in subsurfce tunnels, like a subway going in an endless highspeed circl

dkosmari As far as gravity goes you can go as low as you want for the most part. There are some exceptions, but mainly the return to normal gravity is what causes problems since your body quickly adapts to microgravity. Astronauts on the ISS are actually really comfortable until they return.

I want to know if I can pee and poop without needing to vacuum it out of my orifices.

Yes you can the ISS has a toilet. Actually shouldn´t be a problem to live in low gravity as long as you don´t plan on returning to gravity ever. Well in the Expanse they came up with fancy medication that keeps your bones strong so if you have that it might work no problem.

You can poop just fine in zero g. Here's an experiment. Stand upside down on your hands and try to poop upwards. Piece of cake. If your bowels can overcome negative g's they can surely overcome 0 g.

Thank you for that... unpleasant imagery.

That "train" idea was exactly what I was going to post...and, although I thought it was an original idea, I read the first book of that trilogy a long time ago so my subconscious probably just plagiarized it. To go a little farther - since I can't recall if they did it in the books - I'd say hollow out the interior for use as a micro-g space-dock for the ships, slap rails around the outside, and basically make a space-version of that carnival ride where you get spun around-and-out in little seats that are tethered to a spinning central pole, in this case using nanotubes and relatively small pods to keep the math realistic ("extended stay hotel rooms" for you and your crew to get some g's, go to meetings with others, etc.). Now that I think about it, Neil Stephenson's recent book Seveneves does something like that, and AFAIK he actually did the math/got help from people that could do the math for him. Damn my memory once again! :O

I don't think hollowing the interior to make an spaceport has any practical benefits over building the port at the surface.

It makes sense for several reasons: 1) Assuming you're mining the asteroid, you've got to remove material from _somewhere_, and I see no reason why you wouldn't construct mines relatively the same in space as on Earth (i.e. "dig where what you want is"...which is likely to be inside, not on the exterior of the asteroid) and 2) Kepler Syndrome is already a known/potential issue around Earth; I can only imagine how bad it could become around an asteroid that's being mined/constantly visited by ships/etc., so 3) by keeping docked ships inside of the asteroid, you not only have much better control over debris, but you effectively shield the ships from all external sources of damage as well.

Tbf, by the time we see the asteroid colonies, like the one that goes off into interstellar space, they have much more advanced technology. Enough to have a city on wheel on Mercury, undersea ones in Europa, fusion power, and they apparently can make diamonds for peanuts, given they had dams of the stuff on Mars.

Larry Niven had a slightly different method for creating asteroid stations in his Known Space books. They would take a reasonably pure nickel-iron asteroid, put a heatproof balloon in the middle, then use solar mirrors to raise it to melting point. They'd inflate the balloon up to the right size and shape, then let the whole lot cool. Seems more reasonable than just hollowing out an asteroid, and the original asteroid doesn't need to be anything like as large to produce the same size habitat, either.

I want to know the cable thing, too.

Ignoring engineering details like material strength and resonance modes? Conventional launch of bootstrap material, then build the tether down from geostationary orbit while simultaneously building the counterweight up. Once a minimal tether is in place, you can haul additional material up the tether and reinforce it.

In Niven's books, humanity has infinite cheap energy. So heating a metal asteroid up to melting point and inflating it is plausible, in his fictional universe.

Elevator cables: elevators are only going to usefull in fairly high-gravity environments where rockets are big and dangerous. An elevator at Ceres or Eros would be easy to do but wouldn't save much over using low-thrust rockets. On either you could do all your launches with catapults. Getting an elevator cable would be just a matter of fabricating it in space. The minimal cable, only large enough to accomodate a modest climber would still mass around 100,000 tons, close to 1,000 SLS launches. That would still leave the challenge of seamlessly splicing the 1,000 or so cable sections in space. An easier approach would be to source all the raw materials from a carbonaceous condrite and fabricate the whole carbon nanotube or graphene cable in one continuous process. Attach an archor to one end and gently lower it to the surface of the Earth. The only necessary thing it that the center of mass of the cable is at geostationary orbit above the point where you want to anchor to on Earth.

Kevin Shepardson, A stationary space elevator is assembled in orbit. Preferably at synchronous orbit but, perhaps, the structure is gradually moved outwards with ultra-high efficiency engines. The center assembly (micro-g) hub is supplied with spools of fabricated graphene tube segments. Splicing and composite layering is done until the ribbon is ready to deploy both up (out) and down (inwards) simultaneously. The initial elevator fabrication must reach full length before it is ready to be lowered into the atmosphere and anchored on land or sea. Until then, the excess length is stored on spools and/or the ribbon cable will be deployed folded over a pulley at the weighted lower end. With folding, the true endpoints can be maintained in the center micro-g fabrication hub until self-mass and layering requirements preclude this. There are several harmonious ways to continue fabrication. One is to install fabrication plants and/or habitats at both top (outward) and bottom (inward), which need to be weighted anyways. The inner end will eventually experience near surface gravity, even while above the atmosphere. The second is to fabricate and deploy the actual ribbon endpoints from the hub. Of course this requires folding at the weighted ends. The third is to shuttle along the existing structure, bonding new composite layers. The outwards section can be shorter than the inwards section if a greater mass is maintained at the outer end. Both must be adjusted to maintain balance so that the micro-G fabrication plant can operate correctly. A side effect of lifting all mass to the geostationary point is that a large amount of potential energy is stored. The act of deploying the cable will allow this to be converted to electricity, for example.

sonnder you'd need an extremely strong frame system to handle such torque.

sonnder I wouldn't think so, because with a wrench you're trying to overcome material sticking forces, which is why more torque is helpful, but there isn't any such forces in the vacuum of space. The only force to overcome is this YORP effect mentioned. It becomes a relatively simple matter of just imparting the needed momentum.

Yes, that would greatly reduce the thrust and/or time required to achieve the proper spin rate. And you would not need a frame system to handle the "torque", you would put the engines on a 100km tall tower than run a cable from the top of that tower to the horizon. The cable would be under tension pulling tangentially to the surface, the tower would be under compression.

Hyrum Diesen yes! But only very sightly. I feel like Vsauce has brought it up before. I think it's a difference of 1 lb or less.

Yes! That's why it's better to launch rockets closer to the equator.

For fast weight loss, travel from pole to equator!

Fabrício Lara you’d lose more weight walking the distance, than you’d lose because of the spin

Just the flotation effect of gas pressure on the volume of our bodies negates more than that I'd say! Just that we don't notice it since we weigh in with that already subtracted. How much more DOES a human weigh at earth sealevel in vacuum compared to in atmosphere ?

The Earth is considered one of the small planets in our solar system... at 12,750 km in diameter. Eros at 34km by 11km by 11km is roughly a billionth the volume of Earth and about 10 billionth the mass. Our sun, just 1 of about 400 billion in the Milky Way, weighs in at 3 million times that of Earth. So, yeah, Eros is small.

@jonny j - clearly, Lenard Segnitz is *agreeing* with DahVoozel.

Earth is the 5th largest planet and the largest rocky planet so it’s hardly small

Did the math on that, watch the whole video.

Well at least we know there won't be any Metallica

For Ceres it would have to be about 30km thick and made of perfect carbon nanotubes.

oh god, that's a fair amount alright

MrNuclearturkey thats an understatement

Feint, NASA has experimental fission thermal reactors in the kilowatt range.

It lifted off once and landed again, it's still there.