A Realistic Way to Make Space Habitats From Asteroids

[@PsyllyCymon]

2:53 _"The idea has been floating around for a while"_ (not even a grimace, what a legend!)

[@frasercain]

So many space puns, all the time. I'm numb at this point.

[@therrdon1841]

I am 67 years old. I was a firm disciple of Saint Nyquist. I worked in Data Networking. When I started in the early '70s, Baudot code was still wide spread though 8 level was gaining favor. I remember reading early papers on "the WorldWide Web" and scoffing at the idea because bandwidth limitations would not allow reasonable transmission times. When one of my Grandmothers was born (1896), Electric lights were not even widespread. She was still alive when I got my first (300 Baud) MoDem. I was working for a now bankrupt manufacturer when they exhibited a 10 gigabit switch prototype. In short, I HELPED BUILD THE FUTURE, and can barely comprehend it.

[@2150dalek]

Good analysis. I worked in Motorola in assembly, then technician work keeping machines going I didn't totally understand. Even after looking at schematics ...but they work.... I'll bet an honest Doctor will say the same thing.

[@realmstupid-on8df]

You are the man, man!!!

[@cletusbeauregard1972]

There was a sci-fi story from the '70s-'80s about asteroid settlers who melted a metal-rich asteroid and inflated the interior while it was still hot, and then spun it up after it cooled. They made the inside of the spinning cylinder a place for women Belters to go to for the duration of their pregnancies; they called it Confinement Asteroid or something like that.

[@septegram]

I was thinking the same. Bore out a nickel-iron asteroid and fill it with bags of water. Use solar mirrors to melt a plug. Spin the asteroid and start heating it up with solar mirrors. Once it's fully molten, the water boils and expands to blow it up into a solid shell. Let it cool, and you have a hab.

[@AndrewBlucher]

Do the math about how much energy is required ... and how long it will take to cool.

[@septegram]

@@AndrewBlucher Energy is free; a row of solar mirrors concentrates heat along the length of the asteroid. Not sure how long it would take to cool, but there would be ways to speed it up if necessary.

[@AndrewBlucher]

@@septegram Free mirrors? Seriously, do the math. And explain what the volatiles are going to do when heated.

[@septegram]

@@AndrewBlucher The mirrors aren't free, obviously, but if we're at the technological and economic point that we can mine asteroids, a series of mylar mirrors will be trivial. The mirrors aren't free, and I didn't say they were. I said the _energy_ was free; concentrated sunlight.

[@olorin4317]

You're a realist and you get very serious about it at times. Then at other times you can be very enthusiastically hopeful. I've appreciated it for more than a decade. Don't worry about people, most of us are ridiculous.

[@kayakMike1000]

Wouldn't it be a kick in the pants that we find out we are actually the von Neumann probes?

[@miinyoo]

My first reaction was "This guy is either from Easter Island re-animated or from space, can't be both." Adam is very fun to listen to. His lectures are fantastic. Awesome ideas. Great guest, Fraser. By the by, your questions were phenomenal. I can tell you have a ton of experience talking to really interesting people. Shines like a beacon. The whole discussion makes me think of; what is the path of least resistance? If you can identify that path with measured precision, you win the prize when it comes to space faring.

[@tactileslut]

Yeah, the mismatch between the wide angle upward facing foreground camera and the less wide straight back view of the backdrop is jarring, especially when he moves forward and back.

[@chrishorne4016]

Are you talking about the rocinante interior shot?

[@67comet]

Great conversation, good balance of "realistic" and "wouldn't this be awesome" :) ... He's a good interviewee also, perfect amount of off topic as well, made it fun and easy to listen to .. Whoop! Off to check on some Kim Stanley Robinson books :) .

[@pazitor]

Mobile space habitats are a good, very long-term solution to the many challenges that are to come, including an expanding then contracting Sun.

[@00dfm00]

Interesting. Perhaps building large subterranean cities would also be an effective option. Although, I'm sure in 4-5 billion years from now, we'll be able to convert our consciousness into energy and into statis for long term trips to other worlds where we'll be able to create customized bodies and other life suitable for any planet of the many planets we'll be settling by then.

[@pazitor]

@@00dfm00 Closest to that might be uploading you brain to a robot in which you can then underclock or overclock your brain for hibernation or heavy computing.

[@00dfm00]

@@pazitor If we're talking about the journey to another system, I'd rather go to sleep and let AI handle the day to day. Interstellar travel would be boring af. It's the destination that's interesting. At the rate we're advancing in our understanding of life, how it forms and how the brain works, I'm sure we could do much better in millions of years than anything we consider robots today.

[@rikk319]

@@00dfm00 "I'm sure in 4-5 billion years from now," " I'm sure we could do much better in millions of years" I'm NOT sure, 100 years, or one billion years. That's the whole thing about the future. We discover some things we never expected we could do (internet), but we learn other things are impossible due to physics (faster than light travel). And "uploading" or "transferring" your consciousness isn't a thing in reality. You'd be making a copy of your personality, not moving some "soul" within you to another human or android body. What make you, you, would still be in your original body until you die. Sure, a copy of you would go on living, and could copy itself numerous times, but for the original you, that's not the key to immortality.

[@00dfm00]

@@rikk319 While uploading or transferring may not be a thing now, it's reasonable to think we could completely understand how our brains work and replicate it in the future. And no, I'm not suggesting a soul or anything supernatural as that's far more fetched than replicating our neural activity. Also, outside of your brain, there are no original cells left in your body since everything is replaced several times in your life, so the concept of 'original you' is dubious.

[@MichaelBuetKESE]

I had the honor of presenting at several International. Space Development Conference (ISDC), talking about my concept for autonomous asteroid mining using existing technologies. The basic idea is to stop sending scientific research payloads, just a set of rock crushers, and use the "speed" imparted to the powdered material to load up 4 simplified return "silos" with just the bare instrumentation and basic propulsion to send then on a return trajectory for EARTH capture. The silos are designed to stay in orbit, and be off-loaded in space. The material can then be used in space to build spacecraft that will never need re-entry capabilities. Refining tailings are used for space and sun radiations shield on the outer skin of the spacecrafts.. Valuable metals and rare-earths can be extracted and re-entered for funding the entire operation. I worked with Mr. Jerome Pearson, Inventor on record of the Space Elevator, and Edgar Mitchell (Apolo 14) was an Advisor to us.

[@ea9988]

Great discussion and great chemistry. You two should cohost a podcast or something

[@steverobbins4872]

How about this: Find two asteroids that are orbiting each other and roughly equal masses; bag each on separately; tie them together with a tether; and slowly reel them in toward each other until you have the desired spin rate. (Sci Fi idea: over time, the two settlements become hostile towards each other, and extremists sever the tether.)

[@rikk319]

A lot of asteroids are just loose agglomerations of rubble--they'd have to be tested first to be sure they're solid, so a tether would actually hold on to them.

[@steverobbins4872]

@@rikk319 No, I said "bag each". The tether connects the bags together. Rubble inside each bag.

[@GoCoyote]

This would solve the issue of the energy required to rotate the mass to a speed fast enough to create at least partial gravitational force equivalent. The energy required to create spin in millions of tons of material is just incredible. So much easier if it is already embodied in the system. While being drawn together, the material in the bags could be spread out to either side of the tether along the orbital plane with new tethers until a ring is formed that rotates at the desired speeds. A big question is the number of binary asteroid systems available with the needed compositions to make it work.

[@Wordsmiths]

Love this idea.

[@MacTrom1]

In my lifetime, we have gone from rudimentary jets to heavy lift rockets, to moon landings, to interstellar probes. What might be in another 100-150 years.

[@tmhood]

Interstellar probes?

[@jeffmosesjr]

This is why I love your show sir. Two people I would love to talk to about everything in one show. Nice job, even your "distractions" were my favorite parts. Your guest today was one of us, the computer geek, the science nerd, a passion for sci-fi and technology. I can relate, and I love it. Keep doing what you are doing.

[@Edward-om8mz]

Professor A. Frank is nicest, beautifully and smarter scientist ever. THANKS so much 4 this interview 😊

[@istiles1]

I think a variation on your theme would be to also utilize John Ringo's molten asteroid concept in conjunction with Adam's; find a rubble pile asteroid, weave a carbon fiber mesh around the pile while using specially placed rockets to decelerate the rotation of the pile into just one vector of rotation. Once this is accomplished, emplace additional rockets to speed up the rotation until it achieves full expansion of the rubble pile into cylindrical form constrained by the mesh. Then, maintain this rotation while using a host of satellites in heliocentric orbit near the asteroid to either concentrate solar radiation on the surface to gradually raise it to melting temperature, which should provide a casement with carbon filaments running through it. Once this is cooled, place another mesh net around the cylinder & increase the rotation until it is 33% earth gravity. Of course there are many variations on this theme - use different material for the netting, use solar electric lasers, etc. Then you'd need to place lasers around the colony cylinder to be able to eliminate or at least deflect on-coming debris which could damage it. It still wouldn't guarantee safety from CMEs but aside from the most powerful cosmic rays the colony's population would be as safe as living anywhere else in the solar system aside from the earth.

[@bootstrapperwilson7687]

A gripping conversation. Thanks. Three books got me a bit obsessive and optimistic about our off Earth future. These were: 1. "A Step Farther Out" by Jerry Pournelle. He gives so many conceivable solutions to solving our problems of continuing to live in the high style westerners enjoy, both here and offworld (he calls it survival with style). His arguments are backed up with rigorous calculations to show how it can be done. 2. "Engines of Creation" by Eric Drexler. He describes possibilities for living almost like gods, with ability to achieve any physical goal by use of programmable nano machines. Want a 1967 Caddy Eldorado? Buy a few nanobots with the right programming, plant em in the ground, they'll use the elements in the soil to replicate themselves, then mine the necessary materials to make the car. Wait a few days, you've got an Eldorado (the bots self destruct after completion). Drexler addresses all objections with plausible refutations. We just need to get to true nanotech for post scarcity to happen. As for how we handle a world where any possession has almost zero value/cost, who knows? Maybe many folks become selfish spoiled horrors who behave in unthinkable ways, as warned by Dostoyevsky. 3. "The High Frontier" by Gerard O'Neill. Always been fascinated by the idea of artificial living spaces, I think sparked in childhood by the "Seaview" on "Voyage to the Bottom of the Sea." O'Neill seems to give a realistic description of how space habitats could be made without breaking the Earth's economy. Although the book paints an idyllic future, I think Earthbound human problems will go to space with us.

[@element5377]

to an informed roman, we are already "living almost like gods" i will call it the "theory of informatics relativity". sufficiently vague? surviving with style may be necessary to motivate humans to go away from earth. perhaps full on luxury if space farers are too reckless. i like the inflatables and the underground habitats best. self healing of course

[@peterhagen7258]

And don't forget your Larry Niven library.

[@dave7038]

It's kind of fun to think about possibilities for instructions for nanobots as in #2 would look like. I imagine that somewhere you'd have a bunch of information describing the manufacturing techniques and materials available in 1967, engineering drawings for the individual parts, images of the model of car, etc., and software that would take all that in and run a simulation of manufacturing the vehicle to produce a model of the part to be built, including details like the grain structure of a forged crankshaft, imperfections in upholstery stitching, etc., and the nanobots would build from that so the final artifact could be as indistinguishable from an original as possible.

[@ElijahPerrin80]

The moon is a perfect supply of astroids for now and an even better target to land and mine astroids as we grow, learning to build in space or orbit will give us the ability to build on a much larger scale.

[@EnneaIsInterested]

I don't know, basic processing of those stony asteroids using solar mirrors, what are essentially giant vacuum machines and orbital solar furnaces seems a lot easier than dealing with carbon nanofibres and similar.

[@ralboraggins9564]

We just need millions of people here on earth weaving by hand. and it all gets shipped up there to make giant baskets.

[@jamess.2599]

I just found your show and its amazing! Thanks for all the hard work.

[@hodor3024]

Hey Fraser, a common theme of these megastructures is "carbon fiber" or even "carbon nanotubes" and while possible in theory, it skips the problem of getting a huge amount of carbon fiber to the asteroid. I know high strength fiber can also be made of molten basalt. Could a similar fiber be made in situ from an asteroid itself and how large could a structure made of asteroid fiber theoretically be?

[@olawlor]

Basalt fiber could definitely be made from asteroid rock. Typical tensile strength for basalt fiber is about 1000 MPa, which is much stronger than Dr. Frank's paper suggests is needed for even a 3km radius hab (not considering atmosphere pressure).

[@hodor3024]

​@@olawlor Cool, thx! So a solar-powered, basalt fiber producing robot (if that's feasible) could convert one rubble pile after the other into cylinders.

[@olawlor]

@@hodor3024 I've melted basalt into (neat black) glass with a 0.4 x 0.6 meter solar concentrator, so it sounds plausible to me! The hardest part is making the autonomous robotic control system reliable, especially given the unknown geology and abrasive dust.

[@ralboraggins9564]

It seems to me that almost everything needed would have to be brought there for the first iterations. Maybe it's better to attempt to program drones to do all the construction.

[@perceivedvelocity9914]

This was a fun conversation. Hard science fiction may be fantasy but it could also could create interesting thought experiments.

[@lsxbeastful]

Had me at Roci...

[@PrinciplesMatter]

Many of our common items were likely inspired by & considered to be science fiction. I went from dreaming of a Star Trek communicator to having something infinitely more capable in my hand right now to both watch this video and discuss it in real time with people on the other side of the planet. It blows my mind when I really think about it...🤔

[@jasonkinzie8835]

Hard science fiction is obtainable fantasy for our descendants.

[@catjudo1]

Greg Bear wrote Eon and Eternity (title?) featuring a hollowed asteroid as a setting. Neat stuff.

[@chipblood]

This was an awesome interview. Adam would be so cool to have a dinner with and just have a conversation like this. One of my favorites' of yours so far. Thank you for bring it to us.

[@oneoveralpha]

If we go to Mars, we get a planet. If we go to the asteroids, we get the galaxy.

[@bazoo513]

The idea of hollowing an asteroid and spinning it would, of course, not work because the tensile strength of asteroid material is not sufficient - it would fly apart. But putting it in a kind of "bag" to contain it would probably work, if we have material similar to that needed for space elevators tethers. Actually, the larger an asteroid, sooner it would fly apart. To get meaningful centrifugal ("outward") acceleration in the central hollow, on the surface it would be enormous. So, it turns out that the tensile strength of covalent C-C bond suffices?

[@peterb9038]

Good interview, there are loads of ideas here, you wouldn't need one third earth gravity to get the asteroid to come apart, you can do a very slow spin at first to fill out the bag , then cerment the exterior wall or melt and cool it to form a skin until it's the required thickness for strength , before spinning up to the required rate You wouldn't need future advance materials for that bag. We can do this today with the avaliable material technology we have. Also reef rhe bag, so once the exterior wall skin is finished, open the reef and expanded the bag , slip it off and reuse for the next asteroid.

[@patrickdejoseph8174]

I am 76 years old and when I was a boy, during the late 1950s, scientists envisioned building stations in space or on a planet using glass. I mean really thick glass constructed from regolith. I always thought that it would be an excellent idea to shield humans from the radiation.

[@chrisoconnell8432]

Great interview! Except you missed the one question I wanted to know, "how do you cap the ends of the astroid cylinder?" You wouldn't need to if you're just mining it, but if you wanted a habitat, then you'd want to cap the ends of the cylinder and fill the interior with air. Wish you would of asked about that but still an enjoyable conversation.

[@jackesioto]

Alternatively, the habitable portion could be roofed. The roof would form a secondary ring, and thus would form a Stanford torus

[@FaxanaduJohn]

Great chemistry between these two. I could have watched double the length.

[@TanyaLairdCivil]

I'm curious how this concept would work for some more near-term realistic materials. What about using something like kevlar, but with a much smaller diameter asteroid? You probably can't get up to the 10's of kilometer-size with materials like this, but it should allow something a few hundred meters across. That's still an amazing size for a space station.

[@user-pf5xq3lq8i]

The cost "savings" in using Kevlar could be lost in increased launch costs to lift more of it. I haven't checked but I'm guessing latest CT designs are about 10x - 20x stronger than Kevlar. I could be wrong there..just illustrating a point lifting costs are a factor as well as simple cost of material.

[@TanyaLairdCivil]

​@@user-pf5xq3lq8i It's not about cost savings, it's about simple tensile strength and materials that exist. Sure, a carbon-nanotube filament could allow you to make giant space cities, but we're many decades away from being able to create such materials at scale, if ever. It's a fundamental consequence of rotation and mechanics that the larger the diameter of a spinning object, the greater the tensile strength needed to hold it together. Thus, while these future materials may allow multi-km scale objects, I'm more interested in what we can do with materials that already exist. Maybe we can't build something the size of a city, but something the size of a stadium in Earth orbit would still be pretty neat. Moreover, as was noted in the video, asteroid distributions are logarithmic, with smaller objects being much greater in number. What I'm imagining is something a bit more near-term. Think using a small existing near-Earth asteroid, bagging it and spinning it up into a station the size of a stadium. If the target object were chosen correctly, it could be placed into Earth orbit with only a small expenditure of delta v. Now we have a massive industrial hub in orbit, with lots of raw materials and space to build out manufacturing facilities. I'm considering this as a way to jump up a few rungs on the space industrialization ladder, not as a habit for millions to live on.

[@Smo1k]

21:03 "Ah, forget it! We don't need planets." This was my epiphany, during a game of Elite on the C64 back in the 80es: Why stop at a doughnut space station? Expand the station along the axis of its rotation; if it works at that radius, the cylinder will work however long you expand it. Getting too crowded? We build longer, like the endless skyscraper, only you stand on the wall and "up" is actually inwards, and you can add as many (sideways) stories as you like. And: If you're turning the space station into an interstellar, multi-generational space craft, have the reactor up front, then the reactant (the stuff you expel to get thrust) will be the light above in the never ending day of chugging along while doing exactly all the stuff we do on Earth. I must admit I had second thoughts when I saw a piece of video art that makes LA stretch on forever, though...

[@bikerfirefarter7280]

Kind of ok with extending a 'doughnut', as long as you avoid the two-axis ratios, then you'd get the problem of it either switching rotation modes (cylindrical/end-over-end) or it flips to 'end-over-end' permanently. If you have difficulty imagining it, think of what happens to a free-hanging long cord if you start rotating it along its length; it soon forms nodes and anti-nodes in resonance with its mass and rotation rate. A similar problem happens with power-shafts known as 'whirl-speed'.

[@Smo1k]

@@bikerfirefarter7280 Yeah, I know this effect. I think it can be counteracted by adding this consideration to the water flow (whether for cooling or all the other uses, we have for plumbing), or ultimately by setting up aligning thrusters in plenty of places. A long cylinder which would ever need a change in orientation would need many points working in concert, anyway: If you only have them at nose and tail, the whole thing would collapse like a tower of empty cans at the smallest alteration.

[@bikerfirefarter7280]

@@Smo1k no collapse, self gravity insufficient. Fluids wouldn't solve it either. Thrusters wouldn't work either. The momentum exchange goes up to really high values at certain ratios. Check out 'shaft whirl speed' and 'axis flipping' on 'Net.

[@JFrazer4303]

An object with a long center of mass, rotating around that long axis is inherently, disastrously unstable. It wants to spin end-over end. Yes, you can apply active stabilization, but a good engineer doesn't design to defy real-world materials and physics and apply complexity to try to overcome the inherent design flaws. (the Space Shuttle was an example of that) O'Neill never proposed the "Island 3" huge 30km long cylindrical habitats as an actual design, but as an extrapolation of what they'd found that real-world engineering could do. The NASA Ames / Stanford studies found that well-known methods (in the '70s) could build a torus or drum shape up to 30km diameter.

[@Smo1k]

I know about the effect that causes end-over-end rotation out of axial rotation, but one of the answers I've found in SF is a cylinder where the hard parts (basically, the cylinder "proper") rotates one way, while all liquids and gases rotate the other in their systematic circuit, so that from a mass perspective, the cylinder isn't rotating. One of the things often overlooked is the amount of water you need to have on board, if you're to grow your food on the station, and that food isn't to be dystopian in its lack of diversity. Add to this that you'll need to move heat around, and that nobody wants to live in a place with no green things, and you'll quite quickly reach a couple of tons of water which needs cycling, per human inhabitant. And since we're dreaming, I don't see why we can't add more water to the equation, so that the difference in speed to maintain equilibrium between fluids and solids doesn't get out of hand...

[@dadsonworldwide3238]

We are entering a 100 years of the transistor age that wouldve allowed this zoom youtube calls in the 1950s but they needed mechanical trial and error to get here with the same tech. The horse and buggy age lasted a long time idk that the transistor won't be it. It very well could be.

[@joeymillette5870]

Cue the picture of O'Neil cylinders and I was brought back to the 80s, 9 years old seeing this (and Stanford Taurus) for the first time in a school library book. Yes, that vision has stayed with me ever since. Loved this conversation especially the realistic long term goal outlook of it!

[@Juttutin]

There's this emerging technology of mm-wave cyclotron rock drilling for deep geothermal that glassifies/anneals the rock wall as it goes. I.e. we probably will have the tech to anneal the inner and outer surfaces of an expanded rubble asteroid into very thin but re-solidified rock layers.

[@Wordsmiths]

A similar technology (albeit more of a brute-force approach) was developed back in the 1950s-1970s, using white-hot tungsten "drill faces" instead of spinning tunnel-boring bits. It was powered by a compact nuclear reactor in its first iterations, but later smaller commercial applications used umbilical power cables to connect to any handy (and high-amp) power source. Can't remember the name of that technology right now, but there's a funny story about how the public funding was provided for it... I'll try to look it up

[@SuLokify]

I always figured we'd build nets/cages/bags around mid size asteroids, then heat them up until molten using concentrated solar power. Collect various volatiles if ya need to, eventually end up with a big molten chunk of metallic rock. Spin your lavablob up a bit, separate out different stuff, and slowly start to cool down the remainder with a movable radiator cooling system. Final product is a "cast" rock of whatever shape you need, and piles of various elements, minerals, etc that have been centrifuged out

[@replica1052]

to collect asteroids before they vanish into the sun is a mission - send solar sails to alter their orbits little by little for a bigger and bigger mars moon for stronger and stronger tidal forces (in an infinite universe it makes sense to catch solar wind )

[@shayanirenberg3294]

Why not do something small with existing tech like using a weather balloon and spin it up real slow, then wrap them up with fibers and cement to strengthen them and spin them up to high gravity?

[@BeowulfNode]

While I do agree that current mass production tech would surely have something strong/light enough to make a first go of it worthwhile, I don't think latex or neoprene (weather balloon material) would be enough. Something like Kevlar seems much more likely as an option. Having a too small asteroid will result in one or more of the issues: of not enough gravity to stave off permanent physiological issues, or too small a diameter resulting in Coriolis effects that humans can't handle, or too thin a crust providing insufficient radiation shielding, or too small an area to have it be worthwhile.

[@Grandremone]

😂

[@Smo1k]

27:29 Exponential Growth We are in a situation where: The exponential growth of what we can do in a lifetime is exponentially growing. The science we do does not rot, it just waits to find use, and with every find, the half-life of our exponential growth is shortened. We're living in three orders of stacked, exponential growth: We apply our learning for a longer time today than yesterday, to tools that are better every day, and there's more of us applying that knowledge to better tools every day... The hallmark of imagination is impatience, but soon we'll run out of it 😉

[@tallaganda83]

Love it, The Expanse is the greatest show I’ve seen and this stuff fascinates me.

[@DataSmithy]

The hardest part of that carbon nanotube bag idea sounds like it would be: how to get an even distribution of materials as the spin-up progresses. otherwise you'll have off-center mass causing serious issues.

[@lonetree1941]

This Prof Adam Frank sets the record for “you know,” “right,” “and like” which detracted from his observations.😮

[@LuvHrtZ]

Surprisingly, Manhatten has its own life support system. It's called planet Earth.

[@JohnSostrom]

This idea was first posited in a SiFi books called Ring Worlds.

[@JFrazer4303]

Konstantin Tsiolkovsky mentioned it before 1910. Noordung sketched a wheel station in the '30s. Von Braun in the early '50s. The NASA Ames / Stanford studies and Gerard O'Neill laid out hard numbers nuts & bolts studies that showed that no new inventions are needed to mine asteroids and moons and to build for virtually Earth like conditions anywhere in space. "Ringworld" is space-tech fantasy.

[@maxpeterson8616]

"You're not my therapist, but..." Scary words to hear in most cases.

[@Tiaintherain]

I had a similar idea except instead of habitation. To Separate it’s components by centrifugal force.

[@DeadeyeJim327]

Since we don’t yet have graphene sheets yet, how about a large inflatable bag of lesser strength material capable of containing the asteroid spun up just above its escape velocity? It would allow clearing the center of debris while containing all material. A minimal level of rotational gravity might allow automated processing of the asteroid material within. By targeting a metal-rich asteroid first, robots could extrude girders, plates, and cables to reinforce and support the bag from the outside. With this reinforcement, the station spin may be increased to allow for human safe gravity.

[@owenwilson25]

Whatever material you use has to be suitable for space, withstand the temperature range and dehydration of space as well as hazards such as uv, gamma-ray and micrometeorites.

[@alvermillioncranky8360]

If memory serves, asteroid living was written about in science fiction back in the thirty's and forty's in things like monthly magazines.

[@YodaWhat]

Another great idea to enthuse about: *A Realistic Way to Make Space Habitats From Asteroids* Too bad it is only a half-baked idea. They are basically talking about making a flywheel explode by spinning it faster and faster until it flies to pieces. That does not have gentle results. The pieces become shrapnel, and will shred the bag meant to contain the pieces, unless the bag is vastly stronger than the average load in the dreamt-of final configuration. *What you actually want to do* is de-spin the asteroid, which can be done without rockets, using long tethers and some of the rubble. Then put a bag around the outside, and an inflatable bag down the center of the rubble pile and gently inflate it. That will push the pieces of astrorubble out to the diameter of the container bag (cylindrical or spherical), with the rubble trapped between the inner and outer bags. Then and only then do you think to spin up the structure to generate your artificial gravity. If you still don't want to use inefficient rocket propulsion, that's fine. Use some of the rubble as reaction mass, in a Mass Driver, or vaporize it in efficient electric rocket engines. Also, think about bringing two such baggedsteroids together, linking them with a framework and bearings, then spin them up in opposite directions... each serving as *conserved* reaction mass for the other.

[@GoCoyote]

You are thinking in terms of the force of a high speed centrifuge providing much more than one g of force. Your bed requires very little structural strength to overcome earths gravity, and a rotating space habitat does not have to be very strong to provide earths gravity equivalent, let alone less than earths gravity. This type of system is more like how a rope on a swing provides more than enough strength to support your weight against gravity, or a how the cable on a crane can lift tons of material against gravity. Just take that same rope or cable, and make it into a giant loop where it can support that same force all along its length. Likely a bigger challenge is stabilizing the habitat to prevent harmonic imbalances that might cause catastrophic flexing leading to its destruction.

[@YodaWhat]

​@@GoCoyote- I agree about imbalance, but it would never get to that point. The large boulders in the rubble pile would hit the mesh with a lot of force, on opposite sides and other random places, almost all at once, producing a lot of large *shock loads*. High RPM is not required in order to get those devastating blows. It is a function of the high-ish speed needed to overcome mutual attraction when all the boulders are close together, compared to the much lower speed needed when they are no longer in contact with each other. BUT the boulders will still have most of the higher speed when they reach the mesh, IF the plan discussed in the video is carried out. Your analogies do not involve shock loads, so they do not really apply here.

[@serg3y]

Did they consider air pressure? That adds additional and very large forces for a large volume.. it could be used to help form the cylinder, as apposed to a hoop. I think a *torus* balloon is a better shape then a spherical balloon.

[@tomgarcialmt]

Yes! Yes! Yes! Please do a whole show with him just about The Expanse

[@HankHillspimphand]

What about a heavy metal netting around the asteroid then using its rotation to use a cable then a ship at the end. Couldn’t the wire length determine the g feeling?

[@chris-terrell-liveactive]

What implications do you see for social/political/economic arrangements in colonies away from Earth? I think there are some interesting possibilities that may well challenge the predominant capitalist/democratic models that we have here at present, not least around ideas of ownership, property, value of labour and allocation of resources... I'd be interested to hear your and some of your guests' thoughts on this. Thanks for an excellent episode.. again! :)

[@specialk8168]

I'm wondering what the plan would be once you have a nice, hollow cylinder. Would you put a huge inflatable cylinder inside, or maybe construct a metal pressure vessel inside of the cylinder? Line it with something? Just wondering what engineers would do with it once they have the spinning shell, to accommodate building stuff inside it and, obviously to hold air inside.

[@dustman96]

That's an interesting part of these constant acceleration/deceleration drives that I hadn't considered, that you get constant G forces. Seems like a major benefit for human space travel.

[@Smo1k]

Inside the solar system, this will be important. Between the stars, though... Once you hit 0.25 c, the energy required to maintain a fixed acceleration makes like a hockey staff. You're going to need other means to get a gravity.

[@brianolumo]

“All we’ve ever known is low-g and an atmosphere we can’t breathe. Earthers get to walk outside into the light, breathe pure air, look up at a blue sky, and see something that gives them hope. And what do they do? They look past that light, past that blue sky. They see the stars, and they think, ‘Mine’.”

[@John_Weiss]

22:03 "Gravity wells are for suckers." The inhabitants of the Orion's Arm Universe Project would agree with you. [I'd include a link, especially to their Bishop Ring entry, but alas, KZbin doesn't allow links in comments anymore.]

[@mariokajin]

One question, what is the resistance of carbon nano filaments/fabric against UV, X-ray, micro meteorites etc.?

[@grantsiemensma4978]

The red Mars book series is awesome. I'm Dyslexic and I managed to understand and enjoy it. BTW really enjoying the show.

[@paulwollenzein-zn1lh]

Larry Niven has his Belt society used the semi simple idea of hollowed out, and then you place some water in bags in the center. Spin it on its axis. Place solar reflectors to shine on it. Wait until the bags of water start to boil. And as it spins, it is being heated up from the outside to the inside. And when it reaches the critical point when the water starts to boil. When it reaches the point you have, hopefully, calculated properly the bags of water burst, causing it to expand dramatically, but under controlled circumstances. As it expands it changes into a cylinder, possibly more or less than one. But if you combine this idea, if possible, you can get more control over the final shape!

[@paulwollenzein-zn1lh]

z"a semi simple idea of hollowed out ASTEROID, and then ?

[@ModelLights]

Had this in mind for ages, and as others have said no doubt there are stories with similar ideas long before mine.. 60 or 70 percent iron asteroid, 1/2 mile diameter. Take it by another larger asteroid, for gravity assist. Interplanetary superhighway to around the Sun, heat up and rotocast it into a 1 mile diameter shell. Ends up about 100 feet thick. Let it cool until the iron has most of its strength, then insulate the outside to retain heat. Insulate the inside, fill with dirt, animals, people, etc. Heat kept in the shell should be the power source for generations. Keep it near melting temp so it's hot and easy to cut, shell the shell and make 20 or 50 thinner bubbles instead of just one. Should be relatively easy to take a million or few people and go out to Saturn and Jupiter for a while. It's definitely a resource to be used, it's already out of the deep gravity wells so you're halfway done before you start.

[@tsmspace]

my open source story project would go well in one of these big stations. "ace racers sp tsmspace" , but in my story,, the spin station must be periodically de-spun for maintenance. At times, the station must have large objects docked to the ring itself, which would give it a wobble if other material isn't moved around for balance. During this maintenance period,, there is no gravity on the station, resulting in a big party for zero-g sports. And of course the focus of my story is racing small cold-gas FPV drones. So while normally they must be raced around the docks or other obstacles,, they can be raced around rubble piles and landforms on the inside of the ring,, so like the mountains in popular space games. (being so small as drones, it doesn't take that large of a pile to be like a mountain) ... The pilots can have that space game experience of mountains and valleys in real life (with no gravity or air friction,, or sometimes even WITH air friction)

[@brettselph7591]

Actually, there is no need for graphene/carbon nanotubes, which is good because Unobtainium tends to keep things in the realm of science fiction. We have three problems: cosmic ray shielding, gravity replacement, and atmosphere retention. Separate the shielding problem from the other two, the Herculean physics problem almost disappears, and the cost goes down drastically. Separating all three problems makes it even better (incrementally buildable), as explained below. 1. Shielding with rubble retained by a "bag" or sleeve does NOT require that the rubble be spinning very fast. Cosmic rays don't care how fast the rubble is spinning, just how thick it is. Indeed, the "rubble sleeve" could be spinning so slowly that the self-gravitation of the rubble is almost in equilibrium with the centrifugal force. You're only trying to get it to "stay" in the desired shape, not maintain a simulated 1/3 g that the rubble ITSELF experiences. Much more ordinary materials, such as fiberglass or basalt fiber (which is stronger than glass fiber) would be sufficient. Depending on the composition of the asteroid, "basalt fiber" or some asteroidy-equivalent might even be a "local" material mined from the asteroid. 2. Gravity replacement only requires that something INSIDE the rubble-sleeve be spinning at a faster rate. Visualize a tetherball, and you get the idea. Since it's only a habitation module rotating about a central axle (a balanced pair of modules, initially), we can manufacture modular habitation units on the moon (for convenience and quality assurance) and send them to the asteroid on the ion drive slowboat. Since it spins INSIDE the rubble sleeve, (coaxially with the rubble-sleeve spin axis), the assemblage of modules can spin at whatever rate you like. Full earth gravity, if desired. The "axle" from which modules "dangle" is a stiff tube mounted on "pylons" anchored radially outward into the inner surface of the rubble sleeve. Gotta keep some clearance from the rubble or everybody dies, but that's just a length adjustment. The initial "dumbbell pair" can be added to incrementally. Three modules would have a 120° angle between them. Adjusting the length of the suspension cables, or moving a dead weight up or down along the cables to adjust the dynamic balance, would accommodate sight differences in mass distribution, which would inevitably arise with workers and material moving about. 3. The prefab habitation module is obviously air tight. The amount of material needed to enclose the required quantity of air and life support is tiny compared to the full volume of the rubble sleeve, but starting small and working incrementally (adding modules as needed) makes the project usable from nearly the beginning The eventual design might seek to maximize the usable volume of the rubble sleeve, replacing the individual "dangling modules" with several large cylinders, effectively a vast cylinder partitioned into "bulkheads". But that's a later stage of development. Please see the article in Wikipedia on basalt fiber to find out just how amazing this material is (three times stronger than steel). And yes, I have devised a way to make it in space. The earth process requires gravity and gas pressure. But there's a way around that. I promise. This comment is long enough 😝. If anyone is interested, just ask, and I'll detail in a follow-up comment, how to make basalt fiber in a vacuum, in zero-G, robotically. Also some other details about the axles and the pylons, such as making the axles and suspension links as rigid air-filled tubes that link up the modules, allowing workers to move among and between them without suiting up or losing precious air to airlock activity. ...Vaguely like Jeffries tubes (named after Matt Jefferies, prop and set designer of the original Star Trek). Will they call them Brettsky tubes after my childhood nick? Prolly not!

[@Peace2051]

Absolutely amazing that this discussion didn't even acknowledge the Ecological Overshoot Unraveling. No worries, just imagine all of their projected "stations" built as earth sheltered habitat in an ever warming planet per centuries if not millennia per the IPCC reports. Yes, the Climate Emergency is a thing.

[@jammin8300]

What if you had one of ur rotating bags trailing in the wake of an impact like say the dart Misson , would it collect up the material from trail???

[@TraditionalAnglican]

Robert Zubrin has said the ideal transit time to Mars is 6 months, and that is easily doable with chemical propulsion. No one is talking about doing interstellar travel using anything that isn’t at least 5 km in diameter * 30 km long & contains fewer than 50,000 people living, working & breeding together. ATST, most interstellar colonization will be done using fleets of 100 - 1000 of these vessels.

[@tiagotiagot]

How would they ensure the distribution of mass is kept even enough that the cylinder doesn't end up in a runaway redistribution of matter where it either bows out in middle and goes banana (before potentially breaking) or just starts getting more and more sideways shooting the matter towards both ends of the cylinder, or possibly some other more squiggly mode?

[@edreusser4741]

We have the technology right now to make the containment bags you are speaking about, it would cost a trillion dollars right now minimum, but it could be done. We just need to be able to do it easier and cheaper. It simply needs scaling and refining and, of course, mountains of money. It won't take 100 years. I would be surprised if it takes 20.

[@TimelineDunkley]

That's your gravity right there. You can turn it into a space station you can walk around and stuff like that because now you have gravity. That's a good idea, also the asteroid might have hydrogen in it, you can get oxygen and water. And maybe you could be a power source. I think that's a good idea 💡

[@jackesioto]

Sounds like a great idea! Though i would suggest enclosing the habitable portion to immure the air. Perhaps thick glass could be used in at least some areas of the roof to allow natural light in and maybe give a veiw.

[@JeroenvanGutsem-u7e]

translucent aluminum

[@notlessgrossman163]

Wow awesome vlog, Ringworld engineering level stuff.. love it. What comes to mind here is how would nanotube fabrics be manufactured at that scale? Nanotechnology is the way at different scales

[@alexjband]

2312 was a great future-tech book too!

[@you2tooyou2too]

The mass of the CNT pig-skin, and the energy needed to convert enough available carbon to weave it, are fairly simple but essential calculations needed to make or break the practicality of 'spun-up' asteroids.

[@filonin2]

Maybe you could do this with comets too? Put a strong membrane around the comet, spin it up, then melt it using large solar mirrors so that it flattens into a donut or disc shape, then let it re-freeze?

[@00dfm00]

Because of a comet's highly elliptical orbit you'd have to constantly deal with incredible fluctuations in temperature and the resulting outgassing when approaching the sun.

[@jeremysart]

Adam is always a great guest!

[@yapdog]

These discussions are always great. The optimism in contagious. However, we're not sociologically advanced enough to achieve the kinds of expansions into space our kind tend to dream about. In fact, we appear to be devolving into an era where truth is relative and belief trumps fact.

[@bananenasphalt2172]

WOW - that really really inspires me! Thank you!

[@tracemiller9924]

That rumble spin up, will be a mining operation, as well. I don't how much metal is out, but eventually you will need to go get it.

[@maxpeterson8616]

The issue is, gravity wells is where all the matter is. That's all the interesting, useful, and necessary stuff.

[@JonathanDLynch]

Regarding O'Neill cylinders. It seems to me that we don't need to build them directly. Rather, we need to focus on building robots that can mine asteroids and build cylinders mostly on their own.

[@garypaech1014]

It’s my understanding that carbon fibre materials are broken down rapidly by exposure to radiation.

[@bazoo513]

~ 21:00 - Iain M. Banks' "Culture" (speaking of superb SciFi) doesn't need planets, either. Of course, they have for all practical purposes magical materials and "force fields" to make "orbitals" . rings several thousand kilometers wide and million or so kilometers in diameter (so that they can provide ~1g of gravity on the inner surface with one day rotation period - natural sunlight, no energy expenditure for gravity generators (of course they have gravity generators, but they use them only on ships))

[@mishkosimonovski23]

I have idea: how about encasing the asteroids in steel, then drill metal poles inside the asteroids to stabilise the ruble and finally dig the core out to place a cylinder? I know, too much work.

[@kenmacallister]

A challenge with this idea is keeping the material evenly distributed mass-wise. Imagine if you started refining metal from material in one spot in the ring, concentrating mass or removing mass in one area would cause the ring to wobble because the centre of mass would become offset. So you would need to do everything at three or more points simultaneously (two points could stretch the ring oblate) -evenly spaced around the ring, so that each point has the same equipment and does the same things in processing materials there, and the centre of mass remains stable relative to the ring.

[@frasercain]

I guess as you start the rotation it'll start balancing itself out. But you might have to push a few rocks around.

[@MikeJones-wn5mu]

Good stuff. Something that I don't think was addressed in this conversation is: How do you "spin-up" a rubble pile? You can't just contain it in a cylinder, and spin the cylinder. You would also need some kind of sweeping structures that will apply the spinning force to all of the rubble pieces.

[@norml.hugh-mann]

You place thrust generation at points that compliment each other to induce a spin instead of moving it Ina direction.

[@robertkercher1980]

one of the issues with centripetal force is the diameter of the object as the closer you get to the center of the rotating object the less you experience gravity (simulated). a somewhat exaggerated example would be an object that is 20 meters across versus an object 1oo meters across, spin them bot up to about 1 G rotation and the people in the smaller object will be more prone to motion sickness as well as there being a higher variation of simulated gravity over a smaller space. gravity would be experienced at the feet and as you move toward the head you would get less simulated gravity which i am certain would be uncomfortable and probably not very healthy. If you take a hollow cylinder with a hundred meter diameter and spin up to about 1 G you would experience a much reduced version of vertigo, you would overall have fewer rotations per minute, and a lower gravitational variation from the feet to the head.

[@stuartcarter7053]

Love this interview - kind of frustrated I won't see it my lifetime! One thing I didn't understand was if the 'bag' was a tube - how would the ends be plugged?

[@terminusest5902]

How about Phobos or Deimos. ? Should we build a base there first to support missions to Mars? A safe refuge, logistics base, an observatory and labs. They can assemble optical and radio telescopes. Also some agriculture and mining. How solid is Phobos? Or attach a spinning wheel structure for people to have time in gravity. Prebuild expandable structures that blow up. Then start tunneling underground. Phobo's has a diameter of about 22 km, while Deikos is about 12km.

[@djblackprincecdn]

The Mars Trilogy is my favorite sci-fi series still to this day. Kim Stanley Robinson did a great job.

[@kindlin]

Really? I love reading, and I love scifi, but I can hardly read those books. I made it through 1 and 2, and I'll read 3 at some point in the next year or 2, but man, they are so dry. The LoTR is my favorite book, and people often complain about how boring that is to read, well LoTR seem to me to have 10x the plot and suspense and page turning than did either of the first 2 mars books.

[@djblackprincecdn]

@@kindlin i mean youre entitled to think that my friend. I love the trilogy and re-read it every few years just like i do with LOTR and The Hobbit.

[@kindlin]

@@djblackprincecdn Actually, and this is kind of funny now that I think of it, I initially hated the LoTR when I first read it, and it wasn't until my second reading years later that I actually enjoyed it, and then it became my favorite book; but, it started as my least favorite book.

[@chrishorne4016]

I read LOTR first in 1968 when the trilogy came out in a single volume paperback. I still have that book, I used to read it every. Couple of years but lately it's been about every 5 years. Another brilliant series is EE doc Smith's Lensman series. The fictional generators that could nullify mass and therefore inertia made Interstellar travel a piece of cake?

[@HebaruSan]

Does it collapse back down if you arrest the spin? Or does the concrete-like property he mentioned keep it in shape?

[@JROD082384]

You wouldn’t want to arrest the spin, because that is what generates an artificial “gravitational” force that’s really centrifugal forces that “sticks” objects to the inside of the cylinder.

[@DominikJaniec]

thank you, my question is: how far is a safe space from solid rocket boosters flame or other engine types, for an astronaut in their outer-space suit

[@bikerfirefarter7280]

Stop it, get some help.

[@Wordsmiths]

It depends on the solid rocket motor or the liquid-fuel rocket engine you're talking about, and where exactly the spacesuited crew member is, and their relative velocity compared to the rocket. Oh, it also depends on whether this "close encounter" takes place in an atmosphere or in the vacuum of space (since I suppose a crew member could don a space suit on Earth or Mars, hoping it will protect them from a nearby exhaust plume) Scenario A: the rocket nozzle is pointed directly at the astronaut. Answer: Hella far away. Far AF. Especially in a vacuum, where there's no atmosphere to slow down and cool down the superheated exhaust particles that are being blasted at the astronaut at [insert specific impulse of the rocket here]. But even in an atmosphere, the rocket plume will create a pressure wave powerful enough to pulverize concrete. The exact answer depends on the size and the thrust of the rocket motor or rocket engine, but if it were me in that space suit, I would be unhappy and nervous about standing in the path of the exhaust plume when a rocket engine lit off if I was any less than three miles away. The further the better. Scenario B: the rocket nozzle is pointed slightly away from the astronaut, enough so that the direct exhaust plume will miss them, and the astronaut and the rocket are stationary relative to one another (sharing the same orbit, or the rocket is on a test stand and the astronaut is standing to one side nearby, etc.) Answer: again, the exact answer depends on the size and power of the rocket, but if you're in the vacuum of space, you're probably going to be fine. Unless the radiant heat from the passing plume or from the bell nozzle begins to cook you, if you're close enough and the rocket is powerful enough for that to happen. Scenario C: the rocket is firing and the spacesuited astronaut passes through the rocket plume momentarily. Answer: again, it depends on the size and power of the rocket, how close the astronaut is to the combustion chamber/bell-and also on how fast the astronaut is moving. Think of the old children's game of passing your finger through the flame of a candle: as long as you are moving your finger at a certain speed, or faster, you feel nothing, or maybe just a bit of warmth. But dawdle in that candle flame and you'll be crying for your mama pretty quick. Same situation here but the stakes are much much higher. Outlier variables: If by "other engine types" you want to include electric ion thrusters, you could probably hold your bare hand right in front of them for half a minute before you felt any pain, maybe longer (and the pain would be from ionization not actual heat-more like a sunburn than an actual flame against your hand). But if by "other engine types" you want to include nuclear salt-water reactor rockets, I'm not sure there is a "safe space" for that astronaut anywhere in the detectable plume of that rocket. Rather than superheated water vapor (from H2/O2 and methalox rocket engines) or heavier superheated carbon-compound molecules and particles (from solid rocket motors), you'll be blasted with super-superheated radioactive salts possibly mixed with microscopic depleted-uranium droplets, traveling at three times the speed (iSP) of most rocket exhausts. Remember, it isn't just the visible flame and immediate heat of a rocket plume that can do damage. The pressure wave is tremendous too, compared to the size of the rocket motor: ask yourself how much mass that rocket motor is able to push, and how fast that rocket motor can accelerate it. If it's a cold-gas reaction thruster that is meant to gradually turn a modest little space capsule or satellite, that's one thing. But if it's a main engine for a big orbital-class rocket, either first or second (or even third!) stage, it imparts a hell of a kick to a very heavy payload-and sends an equally powerful kick in the opposite direction, in the form of an exhaust plume. The content of the exhaust plume matters, too. If it is composed of tiny cold xenon atoms, even if they are accelerated to insanely high speeds by an ion thruster's magnetic fields, they are just xenon atoms. Individually they don't have enough mass to penetrate your spacesuit or even your skin, even if they are expelled from an ion thruster. A good ion thruster will offer about the same thrust as one hummingbird. The ionization of the xenon atoms, not their speed or mass or toxicity, is what you need to worry about. On the opposite end of the exhaust plume scale you have solid rocket motors and concepts like the NSWR. Those emerge at insanely high temperatures and velocities, and many of the exhaust particles have a lot more mass than mere xenon atoms. And the particles themselves can be toxic: bits of unburned solid rocket fuel, flinty flecks of carbonized fuel, and in the case of the NSWR, it's all insanely radioactive too, and only some of the uranium is "depleted" or transformed into less-radioactive heavy metal particles in the combustion chamber. Enough to sustain the combustion chamber's criticality of course, and that's enough to give you a bad day a mile away. Or ten miles away, if you're in outer space where nothing is slowing those exhaust particles down, and they are cooling off more slowly too.

[@saumyacow4435]

One of the things I was taught in Engineering was the Law of Conservation of difficulty. In other words, no matter how you try to refactor the problem, every solution will simply result in difficulty of a different form. Now, what I see in these spinning asteroids is another example of the LofCofD. Or put another way, what's the difference in terms of difficulty between building a big carbon nanofiber structure around an asteroid and spinning it or else simply dong the same scale of engineering to build a "hull" and then transfer into that hull the mass of a "rubble pile" asteroid. After all, what you're doing here is using the asteroid as building material for a shield. And that then boils down to how you're going to build the machines to manufacture the megatons of carbon nanofibers. And the vast fusion power plants to power all of this. And once you've done all of this you still need megatons of materials to build the living spaces within - no real difference here to the problem of building a massive space vehicle. And then of course you need all the consumables. The water, the air.. etc etc.. And a massive fleet to transport all of that. And yet more power sources.. and you end up having the supporting infrastructure, mining, transport being far more complex and costly than the structure you intended to build. So then, if you really were absolutely determined to have lots of humans living in space then just simply build yourself a big regular cylinder. Mass produce metal structure and assemble them in larger and larger blocks, just like ship building. Then weave your carbon nanofibers around the structure. Then slowly add disintegrated asteroids and very gradually spin up the whole structure. Now you've got yourself a world ship - just in a more predictable and controllable way. And it must be said, again, that there is a distinction between things that can be done and things that should be done. In the end you have to step back and ask if any of these human beings on such a structure are in fact any better off than they would have been if they remained on Earth. A rational analysis would say no. It can be done, but it doesn't achieve anything worthwhile.

[@JFrazer4303]

Ending scarcity of energy, resources, and room for growth on Earthy isn't "nothing gained". Proving the way to growth for affluent living conditions for the human population of ~12 billion which some projections say we'll have, while removing heavy, polluting, primary resources and energy production from within the biosphere, isn't nothing. Enriching the global (near inner-Solar system) human civilization (with no new inventi0ons needed) to set to work terraforming and repairing the damage to the biosphere of the Earth and not only survive but thrive during +6 degree C warming, or an ice age, or Yellowstone, isn't nothing gained. Many say that we shouldn't be hoping or planning to survive for so many people. Some even come out and say that things would be better off if we had a mass species-wide die-off to lower the population, but I never hear from those who say so who've also had themselves made incapable of reproducing, or who've "led by example" in other ways. Many say that we're all going to die, so we might as well just lie down and take it.

[@saumyacow4435]

@@JFrazer4303 Umm... Populating rubble piles in space doesn't lead to endless energy. It wastes resources. Also, please explain how 'growth' (population) is a good in itself. We have abundant energy and resources on Earth to provide everyone with a high quality of life. The problem isn't an engineering one.

[@JFrazer4303]

Populating space, in colony habitats built from resources gotten from rubble piles is just habitation for the workers. The endless energy is from the Sun, via satellite solar power systems. Allowing for growth is allowing freedom of growth of the infrastructure for survival, without polluting more of Earth and hoarding of the resources which can be economically gotten down here. Allowing growth so that all humans have an adequate lifestyle to enjoy freedoms, is n engineering problem. We can't do it with the engineering we've ben doing, with fossil fuels and disregarding leaving a good natural environment round us. We can't provide for the 12-15 billion people we're likely to have, just down here, with the infrastructure for survival and growth we've been using. It's not likely we can grow to providing everyone with a good standard of living while transitioning to friendly systems which don't harm the environment, just from down here.

[@GlennJTison]

Take a chunk of nickle iron asteroid and heat it with mirrors to melt, inject it with super heated steam and blow it up like blowing glass. Then shape as desired. Give it a spin and you get a oblate sphere, with 2 flattened pole areas, and after it hardens, an equaterial re gion that can be spun up for centrifugal gravity. As with glass, other shapes are possible.

[@belmiris1371]

Won't this be a race between space habitats that spin and artificial limbs that won't deteriorate in space?

[@dragontdc]

There's an interesting way to mine heavy precious metals from asteroids... wrap the asteroid in laters of progressively finer mesh, with the "solid" bag on the outside. The meshes act as classifiers like when panning for gold. Then maybe run some shock waves through to break up the asteroid more finely, and spin it up. Heavier material works its way to the outside where it can be collected.

[@mikeharrington5593]

Thinking outside the box does produce a mixed bag, but it can also herald new progress

[@CarFreeSegnitz]

Spin the entire asteroid as a radiation shield? Wow, not a good idea on several fronts. 1- there’s no need for the shield (collision and radiation) to spin to be effective. Thus there is no need to subject a huge portion of the mass to these stresses. Doing so invites things to break off and be lost over time. 2- there is utility in having a non-spinning shield. We’ll want a non-spinning platform to mount docking clamps, communication arrays, photovoltaic arrays, propulsion. We do want a spun habitat mounted inside a non-spinning shield like a gyroscope.

[@theOrionsarms]

Or a heavyer but low speed spinning outer shell, and a faster spinning but lighter inner habitation module, they can even contrarotating to cancel precession effects.

[@Enceos]

Perfect survival video game )) 'Oxygen Not Included' immediately popped up in my head when I heard it.

[@spacingguild]

I wonder if there is a way to detect tech signatures around other stars by figuring out if a bunch of objects are spinning at similar speeds.

[@PhysicsPolice]

20:00 Aurora was a good story idea, but it was full of plot holes and unsatisfyingly unanswered mysteries.

[@vomaziarz8056]

Could you create a superstructure around a rubble pile, add one charge to the rubble pile then the opposite on the structure. Somehow have enough charge to defeat gravity allowing for controlled distribution of rubble material. About 1/2 way through the video

[@emmettobrian1874]

Could you spin an asteroid up to a lower gravity, use only steel mesh or Kevlar as your bag, then reinforce the mesh (possibly with materials from the asteroid) and spin it up to your goal acceleration?

[@BeowulfNode]

For a first go, I think this is the sort of idea we'll have to use. There will likely be a trade off for launch costs vs how quickly you can get something useful out of the asteroid. Balancing the costs of running the operation, particularly if/when humans are going there.