Gravity and Radiation Will Not Be Problems on Mars, Moon or Orbital Space Colonies

73 thoughts on “Gravity and Radiation Will Not Be Problems on Mars, Moon or Orbital Space Colonies”

1. This has been worked out, with the answer

   Based on experiments on people in centrifuges and slow rotation rooms, it appears that the minimum radius for an artificial gravity habitat is about 20 meters (i.e., diameter 40 meters). This is not very long. Secondly, the maximum rotation rate appears to be around 4 revolutions per minute.

   https://www.permanent.com/zero-gravity-effects-on-humans.html#:~:text=Based%20on%20experiments%20on%20people,i.e.%2C%20diameter%2040%20meters).

2. The movie? It's alright I guess, for a cinematic version of the original french comic/graphic novel. The new TV series version apparently has rave reviews, but I haven't seen it yet so can't comment. But apparently some people think it's one of Jennifer Connelly's best acting roles to date.

3. I wonder what the required diameter of the station is to obviate the Coriolis Force and the propensity to hurl your dinner with certain head positions?

4. "we will need to modify ourselves to adapt to that environment" – Absolutely, one one of the main unwritten drivers of a Mars colony, to get away from Earth laws of what can be done to the human genome and off-world (Earth) biosphere, with the coming biotech revolution. Mars will probably be a scientific research and development center because it has to be in that environment. Same with the space habitats. Human 'intelligent design' might take some unexpected and exiting turns as the solar system is colonized.

5. Build large with HLLVs—-put lead up there

6. I see. One problem as a time. Eventually, if the human races is going to be a space faring race we will need to modify ourselves to adapt to that environment.

   I see a creature with solar cell wings and builtin ion drives living among the asteroids.

7. Muscles, while a serious issue, are only one of the serious issues with zero G.

   There are a whole lot of systems in our bodies that evolved for 4 billion years with 1g gravity as a fundamental assumption. eg. Fluid movements within your eyeball.

8. I see people mention "Snowpiercer" a fair bit.
   Is it worth seeing?

9. 1. Launder money. Government money -> construction and real estate companies -> political donations. Because going straight from taxpayers to politicians has been (eventually) banned.
   2. Farm votes from people who think that the Hogwarts Express is a documentary about transport systems in Europe.
   3. Farm votes from construction workers. Who aren't stupid. They know how to vote for a decent job.
   4. Transport. Maybe. If the project ever gets completed. And if, by pure coincidence, it's in the right place and going in the right direction.

10. Even 50 years ago nobody saw the economic drivers for 200,000 ton cruise ships that went nowhere in particular. 

    Fortunately they didn't have to stump up enough cash to just build such a cruise ship and hope. Instead they had the option of taking existing ocean liners, which were running out of passengers because of competition from airliners, and repurpose them to show that the market could be developed and grown.

    This is the best and safest way to demonstrate a new market. If you can do it on a tiny scale for a small investment first. Something that needs $1trillion in cash up front will be waiting a long time.

11. lot's of people with shut knees that could be functional / able to work again on the moon doh ;p

12. Cheapest way in the long run is to find the hormone that causes the muscle to stay fit.

13. I would pretty much ignore Island 3 as an actual proposal. O'Neill was a Physics guy, this is to help popular culture see the basic idea of the Physics. The orig drawing had flat ends. I'm pretty sure O'Neill had seen a tank, so that was to make the math easy and clear. My guess! Issac Arthur old "Rotating Habitats" is good, but his "Lunar Industrialization" has the factories on the Moon. Your ideas are excellent, but they should also be valid at much smaller scale. This is happening! The military is going to do ISM with Earth supplied 3D feed stock, that will get things rolling, and make adding in lunar material imperative. I would go slow on humans, but there will be some. Robots are not limited to remote exploration, but a must in Space. Space Solar is the biggie, but most are still talking launch, as in how to pay for it rather than whether.

14. At this point, the best structural material in the Earth system for an O'Neill style habitat is basalt fiber. The loading on an O'Neill colony's structure is almost entirely tensile, and that's the easiest strong material to make from Lunar resources, and has good performance. Not as good as carbon fiber or Kevlar, but the Moon is carbon poor, and basalt rich.

    O'Neill's design with the strip windows requires disrupting the over wrap in a way which strikes me as structurally undesirable, though I agree that it IS feasible to do it that way.

    I would modify it to skip the zero G atmosphere zone, and instead have "roof" of windows a hundred meters up or so, allowing light to be distributed down a hollow center plenum. This surface would also allow for mounting sprinklers to simulate rain, if this was desired. Optimally, this roof would restrained by a network of vertical stays, as otherwise it would be subject to compressive forces that would require a very heavy structure to prevent buckling. Think of the structure as an air mattress wrapped into a toriod shape. Air pressure loading would be locally neutralized in this way, leaving the over wrap to only handle the 'weight' of materials in the colony, a substantially lesser load.

    A non-rotating meteor and radiation shield would have substantial advantages in terms of a location for space craft docking, as well as being structurally less demanding.

15. It is not the provision of g for humans that is the 0 g mfg advantage, not at all! The human hab is a small part of the economy, most is stuff in 0 g factories, which can make human habs or anything. Far beyond anything on planets. We have wasted 20 ISS years on Mars shot 0 g trip tests. Not worth the wait if not going to anyplace that has 1 g at command. Only needed for planet gravity traps, can't get away, can't get enuf , or get too much, or are Venus.

16. Good discussion! I have no doubt that many people will live as described on Venus, which seems far better than Mars due to 1 g alone (does V have magnetic protection? Aurora would be naked eye to us, seems.), also, possible Mars quarantine.
    "planetary surface is an expensive commodity in the long term " This is the best O'Neill argument there is, I think, as most people are feeling that it is already! Showing long term progress in moving to other planets is not going to win much excitement given that it does not solve the problem! 2-3 times what we have now is a good idea for current pop, not anything much for future growth.

    easier to build -> "I don't think that's really true, with current technology. Potentially it's eventually true, but not now." You make a good point. I should use O'Neill term "right" rather than slippery "easier". Clearly, I do not mean "Settlements and most anything are at this moment easier to build in 0 g than any g even tho given the 5 billion year head start 1 g has had, and the bare access to any 0 g at all." Rather, more like "As the Man from Mars" (unbiased new observer), would I choose to build stuff in Space, or on a planet? Or, "Is the surface of a planet the *right place* . . .?" The word "right" includes all considerations to the best competence, just what we are looking for. Which is right, lunar outpost or Halo Gateway hab? The question gets pretty stark if you are not already on the planet. Much can only be done in 0 g, BTW.

17. Well, technically, centrifuge experiments indicate that at least small animals are healthier at higher than 1 g. But humans aren't small animals, and we might do better at lower.

    Anybody who favors colonizing space should want this issue tested ASAP. A small rotating lab, probably bolo style, is in order.

18. You still need radiators capable of rejecting all your waste heat from living at a temperature significantly below 'room' temperature. And sheer geometry dictates that the radiators scale with both the size of the habitat. Stacking floors that are actively occupied increases the amount of heat that has to be rejected, without increasing the available surface to reject it from. 

    I'd recommend extensive use of 'smart' lights that only shine where people are looking, and photosynthesis optimized lighting any time people aren't present in planted areas, but you probably won't be able to stack more than 4-5 floors profitably in a large habitat before you run into heat rejection problems.

    Best bet is a fairly short "Ferris wheel" design, (Fairly short is relative here.) with the radiators 'above' the habitat, permitting passive thermosiphon circulation. Hanging them below looks attractive, but it's backwards from a passive operation standpoint. A decently slow rotation dictates that there will be enough space for radiators within the diameter of the habitable volume.

19. Crude layouts – habitation, communal/ services, lab/ shop work, pad with services, vehicles and repair… seems generic and adaptable as modules – separate and link. Partial excavation of discrete building footprints and plop a shell structure that can be protected/ back-filled/ partially-covered/ submerged for each module. Autonomus support rovers can do some install. Bring up tech and people as needed. Assume anonymous and interchangeable work stations and service support. Leasing of modules. Minimum community sizes with minimal skill set.

20. What is even the problem of Mars gravity that would require 1g gravity machines?

    That's insane. With have no data for partial gravity effects on human body.

    Our data is either for 1g or 0g.

    For all we know, .3 or .6 g can be BETTER for our body.

21. But ease of manufacture is absolutely NOT an advantage for O'Neill, it only gets a short term advantage if humans are extremely constrained in our gravity tolerance, and we don't know that.

    IMHO, research into the long term effects of partial gravity is a high priority need for anybody proposing to colonize space.

22. "Settlements and most anything are easier to build in 0 g than any g."

    I don't think that's really true, with current technology. Potentially it's eventually true, but not now.

    I've pointed out that, assuming the gravity is livable, about all you need on Mars to build a habitat is a balloon with internal stays, and some sandbags to protect it from accidental puncture and radiation. The balloon can be made from polyethylene from feedstock out of your Sabatier reactor for rocket fuel. So straight to ISRU, at a very low ratio of infrastructure to population.

    In the Venusian atmosphere there's an altitude where both pressure AND temperature are human habitable, and breathable air is an excellent lifting gas on Venus: You could live in balloons with gravity indistinguishable from Earth, and the atmospheric circulation would even give you a reasonable day length. Dredges hanging from cables could get resources off the surface. And, again: Polyethylene: Easily manufactured from atmospheric gasses, and excellent acid resistance.

    Just spinning for gravity guarantees that O'Neill colonies require a fairly high ratio of infrastructure to population. 

    The big advantage of O'Neill in the long run is that planetary surface is an expensive commodity in the long term, there's only a few times Earth's surface of it available in the Solar system, while you could build many thousands of times that area from even one big asteroid, let alone materials excavated from the Moon.

23. "…3D printing, robotic assembly and replication will perform most of the work…"
    getting Perseverence, Spirit, Opportunity, even CanadaArm, Mariners and Veneras, etc., and other advanced/simple rovers/ satelites/ space accessories takes large portions of a decade+ to design, test, and implement. And to create an ecosystem of them in orbit or in cislunar or a few light-minutes away with reduced surface control? Often the 'Thing' is easier to do than the establishing of the ecosystem of workers and infrastructure in which to make the Thing.

24. agreed. let's see who the passengers are and where/ why they are going before we design the car.

25. People: it's not all or even mostly about weight, radiation, and gravity. It's only partly about in-situ vs imported materials. It's only partly about AI and autonomous pre-inhabited construction. It's somewhat more about money and technology. It is unlikely about spreading humanity or escaping existential threats or large-scale 'pristine' earth preservation or cults/radicals escaping to create communes.

    It is mostly and predominantly about demand, supply, community, and purpose. It is likely a Serious Misconception that people will simply want (or be able to pragmatically/ economic-sustainably) to live, work, play, and interact in: orbit, on nearby inner-solar-system surfaces, and in-transit between, in the same way they do on Earth. Gated suburban/ex-urban communities on the moon or in rotating hubcaps/ tin cans/ 3D dumbbell/torus shapes ? daily commutes? space cruise ships? Couples on road-trips? Bradbury and Asimov's adorable 1960s 'main street' in space/ inner planets' Notions are unlikely in near-/mid-term or pre-2200s development strategy. Who goes and why? How did they plan/ implement/ faciltate antarctica's research stations and tourist flybys/ near-cruise tours? Planning a specialized community from scratch? what infrastructure is there first? what skills in the team and by who? How do developers recognize the need? – waiting list of top 50,000 rich, pared to adventurousness? governments/ academic cartels' encampments. Good book list on planning moon colonies.

26. Good thinking. Balance of considerations, not just arbitrary rules. And we must start with launching something, so that is part of any plan. Please see Al Globus at nss.org "Space Settlement Population Rotation Tolerance (PDF), Al Globus and Theodore Hall, NSS Journal of Space Settlement, June 2017.

27. Amen!

28. Common sense, not so common! May need magnetic shield too, like Earth.

29. Bezos has a small amount of money, nothing sufficient to do O'Neill w/o economic driver. Trillions in Space. Something Musk is missing, BTW, Mars economic driver.

    Blue Origin has been trying to get the hell off this planet for 20 years now Andrew Tarantola Senior Editor Engadget September 8, 2020, 11:30 AM CDT "Bezos cites the increased energy demands of better living standards for people as a contributor to his off-world goals. “We will run out of energy,” Bezos said during the presentation. “This is just arithmetic. It’s going to happen. Do we want stasis and rationing or do we want dynamism and growth? This is an easy choice. We know what we want. We just have to get busy.”

    "he explicitly said he had no idea how an O'Neil cylinder could be created and the next generation should peruse it, but he will NOT be building one." This stance on Island 3 is a good sign that Bezos understands O'Neill!! Those who focus on Island 3 do NOT!!!!!!!!!

30. Just sleeping in one gee is probably not adequate for long-term health. In recent years we have learned that we need to be upright for health (e.g. standing desks). When you are laying down, the hydrostatic pressure difference between your belly and back isn't much. It wouldn't help with things such as the intraocular & intracranial pressure and kidney fluid management issues.

31. "I think" is the first step towards "I know". O'Neill presented to class in 69 or so. Published in Physics Today mag in a few years. High Frontier 77. So our 50 years of waiting for revolutionary ideas to become possible is now passing. Is the surface of a planet the right place for an expanding tech civilization?

    You show your "serious planet chauvinist misconceptions about simple things" by the serous error in presenting O'Neill basics: "that doesn't mandate starting with them" (Island 3s). I have in the past stated that anyone who thinks *Island 3s first* are O'Neill BY DEFINITION does not understand O'Neill. O'Neill is mass driver (train) now (after wagon training the parts for the first one), ISM now, no planets ever. Altho you are correct in your prediction, I'll bet, we will waste huge amount of effort on gravity prisons. Already have!

    For all you know, 10 years from now we'll invent a drug/therapy that solves all problems, and we won't have to do anything. I love these sort of "grasping at straws" arguments. An open display of stress, I'm making progress!

32. I'm certainly not saying anything *can't* be done. Neurotics are capable of doing anything. It is also reasonable to do multiple reasonable things. However, it is NOT reasonable to make decisions with only the wrong solution presented. Even amongst those who claim to understand O'Neill, I find only ~10 % who do not have serious planet chauvinist misconceptions about simple things. I've been doing this exact thing for over 40 years.

    The notion that things are OK as they are and will work out in the long run is BS. Explain the lack of Moon research compared to Mars. Who is doing the suppression there???? A renegade group of NASA engineers started looking at Moon ~90. They stole Clemetine radio to see water on Moon. They scarfed extra payload on replacement rocket to do LCROSS. None of this could have gone a long planned project route. Had to slip it in. Now, revenge is mine! The Houston paper reported the existence of the renegade engineers a few weeks after I forcefully told the Mars NASA guru "If you are not using extraterrestrial resources, you are spinning your wheels." That statement culminated over 10 years of attending Space meetings where the idea was that Mars Direct/First/Only was the only politically sellable plan, Moon takes too long. So, not realizing O'Neill was correct, we ended up doing almost nothing. For 40 years.

33. Falcon Super Heavy and vehicles like it will bootstrap large infrastructure and engineering projects in space. But I doubt that much of the raw materials for such projects will come from Earth. In Situ will provide resources for projects on the Moon and Mars. Orbital habitats will be constructed from materials harvested from the shallowest gravity wells. 3D printing, robotic assembly and replication will perform most of the work.

34. There is no meaningful heat dissipation in Space. The way Space Wars end is everybody shoots off everybody's radiators, and everything stops. The need for shielding and the trapped air mean keeping factories and such outside, in 0 g prob, so they don't load the settlement with huge heat load. But the square/cube law can be moved outside too, to the radiators, where it is a big deal!! The pipes for moving the fluid to and within the radiators is a big issue of that sort. "The dismal science", statistical mechanics aka thermodynamics. Collecting the *cold* into heavy particles that can be filtered upon return from the radiators will allow the condensed volume *cold* to be moved around inside, the particles no longer having to spread out to the radiator size to work.

35. Settlements and most anything are easier to build in 0 g than any g. So, lunar factories should be limited to the bare absolute required on the Moon. This is the current *hot spot* for O'Neill v planet chauvinism war. O'Neill has recently won the big picture battle for lunar resource use as opposed to Mars Direct/First/Only, a dispute that quite recently seemed to not exist, but has suddenly gone the other way with common sense suddenly infecting the NASA and international Space community. But a small step, as most still think of Mars as the eventual goal, with Moon as practice and fuel. Thus they want to live and work on the Moon to do this. Same mistake, different planet. O'Neill plan: build the mass driver FIRST NOW, 1977. I have totally agreed since 1977, BTW, and have actually caused large changes in Space efforts by talking to the right people at the right time. Then, the factories will be in Space, along with the people. Trillions of them. Is the surface of a planet the right place for an expanding tech civilization?

36. Long term habitation in large space structures makes galactic radiation the primary source of accumulated dose. Shielding from the primary galactic and secondary radiation requires an equivalent of twenty or thirty meters of lunar regolith. Secondary is primarily slowly thermalising neutrons, which is the worst kind of radiation to shield from, hence such volume is required. Habitation in a large space structure lacking such volume puts the crew inside a halo of secondary neutrons, in addition to the primary GeV+ protons. In short, there won't be enough starships to lift that much shielding before someone calls all this out as a very bad idea. Building big in space requires materials from space. That capability is the key to space, not starships.

37. In a not so distant future we will use ship block construction to build large, oil tanker sized cylindrical space ships, 320meters long/40m diameter. The New Panamax canal standard allows you to go to about ~50meters beam. Bigger is better and cheaper. They will be empty on the inside, but using the square/cube law to our advantage, they will be expensive (in total cost) but cheap as in price/tonnage launched. We will launch them once from the middle of the pacific (and not upset the neighbors and environmentalists too much) and start to kit them out. At 40m diameter the inside diameter is large enough for centrifugal gravity but the small radius will cause light headedness and sickness for many. But you can do better: the trick is to realize that the cylindrical shape also is host to ellipses (remember your geometry classes). Smart digitally controlled centrifuges can modify the rotational speed/acceleration along these ellipses, keeping the value as close as noticeable to 1G. As such, you can fit 200m diameter equivalent centrifuges (and bigger) into a 40m diameter construction, solving dizziness issues for people who can't handle roller coasters and keeping diameters within launchable ships, which can be constructed on Earth, which reduces cost alot (propellant is cheap, teleoperated construction in space, even by robots, is not). Just Imagineering of course. The size of the market does not yet warrant the expenditure, until SpaceX and friends enlargen the market first.

38. Bezos simply has the funds to indulge his personal interests, nothing wrong with turning your side hobby into a paying operation if you can.
    Commercial economic drivers isnt the primary motivation there, no one else has demonstrated the willingness to pay the first mover costs on such a scale. Yes, everyone thinks Musk has done the same with his Mars aspirations, that remains to be demonstrated.

    "Bezos has made Space Solar his big project"
    I'll didn't hear about that, will have to look into it.

    Look at his Blue Moon reveal video, he explicitly said he had no idea how an O'Neil cylinder could be created and the next generation should peruse it, but he will NOT be building one.

    —Drake

39. Our problem is that you can't accept that it's reasonable to do multiple things, instead of what you think is the best thing to do.

    You also have problems with the idea that, while O'Neill colonies might be best in the very long run, that doesn't mandate starting with them. Trains are the most efficient form of land transportation we have, but we didn't colonize the continent by train, did we?

    Look, let's just get into space, and if O'Neill was right, his colonies will dominate the future quite naturally, without having to suppress people who want to live on planets.

    For all you know, 10 years from now we'll invent a drug/therapy that makes zero g tolerable, and rotating a colony for fake gravity will be viewed as madness.

40. Mass transit is particularly expensive in the US because its primary function is to launder tax money for graft, with transportation only a secondary purpose, if not tertiary.

41. In terms of maximizing usable space, while also maximizing parkland for mental health and quality of life, stacking makes sense. It does have to be remembered, though, that heat dissipation limits how far you can go in stacking actively used spaces, though not storage space. The downside of the square/cube law.

42. "Also, Boring Company electric tunneling machines will make digging tunnels insanely cheap. It is almost as if Elon Musk has thought about the need for cheap tunnels for space colonies on Mars, the moon and elsewhere." From what I have seen everything Elon has done and all of his companies have been designed with an eye on space from the ground up. StarLink, The Boring Company, Tesla, all have applications on the moon or Mars.

43. Build factories on the moon and then use mass drivers and lunar space elevators to get the materials for colonies. Gravity well on Earth will make it very hard to build large in space.

44. The idea of layers in rotating habs may be in for big advances. We are thinking *planet* when we design large *flat* areas to live on in these habs. Build buildings on that surface. But large hab or bolo hab will make 3D living space, as *below* needs not to be dug, just made, and *tall* just needs to hang down from cables, not supported by foundation as on planet. Add light as C mentioned above, and things like transpo distances are totally different. "Ground floor", what is that?

45. And you can get a much larger structure! No need to add passive shielding, make bigger stuff and *that* will be the shielding.

46. O'Neill intentionally limits examples to *current* tech, 70s-80s, to make it clear. Speculation as to material capabilities just confusing a simple point. So simple most don't see it. The glass is as strong as the rest, almost by definition, or there is some other reason for it. O'Neill covers this question in "The High Frontier", 1977, BTW.

47. There is plenty of stuff in Space to build any O'Neill derived design desired. Not on Earth, however. If you understand O'Neill, the first thing you think of is Space when asking: where? Also, the better materials will lead to equal *bulk*, for radiation shield, but far larger structures. Bigger "massive" in size, but not, uh, mass.

48. This whole topic gets far simpler if you first require some valid reason for people being on Mars for any length of time. There is none! O'Neill published almost 50 years ago, people. What is the prob?

49. Curiously, it is the same Amazon guy who has the different space plan than most. Bezos has made Space Solar his big project, once the pick-up/delivery service to the resources is set up. Above linked Criswell LSP has <big>$$$$</big> potential, hope Bezos has heard of it!

50. If the lower gravity of Mars ends up being a serious health issue, they will need gravity loop trains, at the very least during sleep/exercise periods (if weight blankets are insufficient), and spend the rest of day in regular martian gravity.

    Long term, if pregnancy issues also require 1G, that means the gravity loop trains are also going to be temporary insane asylums for the pregnant. Like a bad joke version of Snowpiercer….

51. If a space company can generate a viable earth business then they can generate the funds to pay for bigger plans.

    Yes, they can and do.
    But a multi-billion multi-decade construction project with no direct roi until project's end, there are easier ways to make money. These are business with investors and their goal is to make money while minimizing risks.

    Why do you think financing a fission power plant is so difficult, $6-9B to finance and no cash flow for 6-10years, that's difficult risk proposition. That's why Planetary Resources and Deep Space Industries failed, it doesn't matter that there is $100 trillion in platinum in an asteroid, that's a multi-billion multi-decade proposition before they will book the first dollar in sales.

    It doesn't matter how much Virgin Galactic is worth, when their reserves hit zero, if they cant refill it they will die, so will Tesla. You can't collect your riches in a decade after your grand plans are realized if you die of a lack of cash flow today.

    Amazon booked sales 0, 500k, 15M, 148M, 600M their first 5 years, losses were $52k, $303k, $6M, 32M, $112M. The Amazon loss model is unjustly used to put lipstick on today's pigs. If you dont have the revenue nor growth, comparing yourself to Amazon will not float.

    —Drake

52. Even 50 years ago nobody saw the economic drivers for 200,000 ton cruise ships that went nowhere in particular. They turned out to have demand enough at prices that were profitable. The lower the cost of space operations the more demand will be discovered. At cruise ship/ resort prices there is demand for O’Neill size space colonies just for vacation travel – costs just have to be low enough.

53. What are you planning on storing in your storage that you won't mind getting a bit radioactive?

    Water and air mostly. A level or two of both would do wonders to reduce radiation exposure in the habitable areas.

    Also, I'm assuming these are LEO or MEO rotating stations that could be built in the shorter term, with those lighter materials brought from Earth. These kind of stations are possible by having them sitting under the planet's radiation belt.

    A lot of these near Earth stations can be built for accomodating thousands of people, before we need to go outside the Van Allen belts.

    Outside, you certainly need more shielding.

54. Virgin Galactic is worth $8 billion and has traded as high as $16 billion. Revenue less than $1 million per year and will stay low for 2-6 years. SpaceX was valued at $74 billion in last funding round. The Markets are willing to fund big space dreams. If a space company can generate a viable earth business then they can generate the funds to pay for bigger plans. Amazon had losses for 15 years and funded its larger ecommerce and cloud computing plans and technology. Tesla lost money for ten years and is funding self driving and large battery plans. Tesla at $700 billion valuation and was near $900 billion and Amazon got near $2 trillion. Colonization and tourism can be far bigger than Virgin Galactic sub-orbital promises and market.

55. I read all sorts of things about global weirding/warming/heating. Alarming! So, as far as I can tell, LSP or perhaps similar L5 station is only plan that solves this AND opens Space, solving the bigger problem that global weirding is only a part of. Also far the cheapest, esp with cheaper launch thanx to Musk. There will be no funding if these plans are basically unknown, while small expensive Earth based plans are endlessly debated. After over 40 years, Space Solar is starting to happen. Even some talk of ISM and lunar resources. Nukes are very well covered, if you don't know about them already.

56. The whole "glass" O'Neil station is a bad idea that predates energy efficient LED lighting.

    Big glass = aim rock here

57. Using lighter material doesn't really help, because you need that mass as radiation shielding.
    What are you planning on storing in your storage that you won't mind getting a bit radioactive?

    You can use light weight, high strength material as your structure, and then packing in super cheap lunar/asteroid rock as your shielding I guess. But the total wall mass stays the same.

58. There are all sorts of wonderful plans floating around that never get started because the up front capital is too much.

    Up front capital requirements are very important.

59. https://www.nextbigfuture.com/2021/03/gravity-loops-in-space-and-comfortable-sleeper-cars.html

60. Big as in O'Neill Space, or big as in compared to the tiny Earth's resources, launched? I have been pointing out for decades that O'Neill plans are independent of launch cost. Cheap/big launch helps, but the plan remains. Launch as little as possible, the Earth is too small to be the source of the material needed for O'Neill big, trillions in the Solar System. We need to start that plan, not some planet chauvinist delusion.

61. https://sf.curbed.com/2018/6/18/17464616/bay-area-subway-train-rail-costs-price-bart-muni

    When the Salesforce Transit Center opensed in San Francisco summer 2018 a new tunnel will be needed to connect it to the current Caltrain terminus in SoMa. The project, known as the Downtown Extension, is estimated to cost $3 billion for each mile of subway, six times more than the average outside the United States.
    The Central Subway, a 1.7-mile tunnel that will connect Chinatown to Fourth and Brannan Streets, is a relative bargain at $923 million-per-mile. But elsewhere in the world, new subways cost half as much. Boring Company – $30 million for 2 mile Miami tunnel and system. I will post about sleeper cars.
    https://interestingengineering.com/boring-company-in-talks-with-miami-for-30-million-underground-tunnel#:~:text=Mayor%20Suarez%20explained%20in%20his,estimate%20the%20previous%20project%20quoted.

62. The important number is the cost per KWe, not the gross amount. How much for 1 cent per KWe for 20-200 TWe? $T is small, for that return. Far better than fission at any size. And, he who does it wins Space forever.

63. I am into big. Thus the site name. Nextbigfuture. Also, into fast, faster and big and bigger and better. But only need the shorter name.

64. You cant get financing for a $8B fission plant without socialism, but you will for a $Trillion dollar space solar proj?

    —Drake

65. O'Neill's stations are bulky and heavy, being made of steel, glass, water and lunar stone.

    We can update them and use lighter new materials shipped from Earth, adding more layers of storage and air between space and the habitat.

    The station doesn't need to be so massive as O'Neill imagined in the 70s.

    Nevertheless, bulky and heavy stations have some long term advantages. Like being able to have a living soil and some ecosystem, due to their potential size.

66. Those living in space (Martians, ….. sleep overnight on the 1-G gravity loop pods."

    This sounds really far fetched. People living on the surface of Mars are going to spend each night in a 1-G gravity loop pod? I totally get the whole rotating space station concept, but surface based gravity lop pods seems completely infeasible. First, there is the cost of building them, second the cost of maintaining them, and last but not least who wants to sleep in essentially what amounts to an amusement park ride???? The ride is fun, but I wouldn't want to spend 8 hours a day in it.

67. Modestly clever O'Neil cylinder design can mitigate any such hazards. Bottom level is storage, then a floor of maintenance and machinery, then a floor of work areas then the large inner area where people spend most of their time.

68. http://www.searchanddiscovery.com/pdfz/documents/2009/70070criswell/ndx_criswell.pdf.html

69. Unless the white swan promises of AI and robotics come to pass, I see no commercial economic driver for such creations in the foreseeable future. Lots of things are possible, the future(it's 2021) is the way it is because there are always easier ways to make money.

70. The reason Island 3 is the diameter it is is that the structural requirements are the same thickness as the radiation shield requirements. Now, there are other reasons to have separate (slow) rotating radiation shield, something about getting hit, but bigger makes everything better and safer.

    "100,000 tons into orbit every day. This would be a large cruise ship every day." Or, factories and mining equipment, if you are into big.

71. Al Globus pubs at nss dot org slash orbital-space-settlements required reading!

72. Agreed that radiation ceases to be an issue with larger structures, as a simple consequence of the square/cube law.

    I do think that, as a matter of engineering, if we discover that Martian gravity isn't adequate for health, this really shifts the priority to airless bodies such as the Moon or asteroids. There's just enough atmosphere on Mars to cause problems setting up that sort of huge centrifuge.

73. Google selenomelanin. Interesting.

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