[HN Gopher] Where is my von Braun wheel?
___________________________________________________________________
Where is my von Braun wheel?
Author : speckx
Score : 95 points
Date : 2025-07-03 13:44 UTC (9 hours ago)
(HTM) web link (angadh.com)
(TXT) w3m dump (angadh.com)
| PaulHoule wrote:
| (1) Assuming Starship makes it to orbit, it enables a range of
| structures larger than the ISS but smaller than the O'Neill
| colonies. A mission to Luna or Mars involves 12-20 launches of
| fuel tankers, for the same cost you can put up a _lot_ of mass to
| LEO. A really flashy space hotel seems practical, as would
| simulation environments for Lunar, Mars and Asteroidal technology
| development.
|
| (2) O'Neill colonies with large airspaces seem impractical
| because you'd need large amounts of nitrogen or some other inert
| gas: you can find oxide rocks everywhere in space but pure oxygen
| environments aren't safe. On the other hand, the atmosphere for
| an LEO baby Bernal sphere would be about 15 Starship loads and
| probably worth it for the visual appeal.
|
| (3) The later work of O'Neill's students focused a lot on
| manufacturing. The proposal to build large structures by vapor
| deposition of metals onto a balloon still looks feasible. The
| solar power satellites shrank considerably in mass and it seemed
| that they could be built more practically from terrestrial
| materials.
|
| (4) _Any_ space colonization effort runs into the problem that it
| needs to be self-sufficient in terms of manufacturing (especially
| Mars) which led Eric Drexler to go off and develop his vision of
| molecular assemblers. Drexler 's proposals haven't aged well but
| something equivalent that combines 3-d printing with flow
| chemistry, synthetic biology, fermentation and other technologies
| is probably possible -- and I think _is_ the critical path. That
| flashy space hotel, however, really is about rocketry and space
| assembly of large structures which really is the unique
| application of space manufacturing; I don 't think space
| manufacturing can ever be competitive for the terrestrial market
| but it can be competitive for things that can only be made in
| space.
|
| (5) Colonization of Ceres dominates all other space colonization
| opportunities in the solar system because there is no shortage of
| water and no shortage of nitrogen. It seems possible to take the
| whole thing apart and build a colony with more floor space and a
| larger population than Earth. You don't get the 0.2 cubic
| kilometers of ocean that we get, but I think you can culture all
| the fish you can eat anyway.
| TMEHpodcast wrote:
| Starship feels like the ultimate engineering gamble, so many
| moving parts (literally) that getting it right might be as hard
| as building the habitats it's meant to launch.
|
| On nitrogen, I keep wondering: if in-space manufacturing
| matured, couldn't we generate atmosphere by cracking water for
| oxygen and synthesizing nitrogen analogues through hydrogen-
| based pathways? Or is Earth's air mix so specific that
| importing nitrogen stays unavoidable?
| bryanlarsen wrote:
| > the ultimate engineering gamble
|
| It's a no-lose gamble though. If they fail we still end up
| with SuperHeavy as a massive, cheaper Falcon like
| architecture. If it succeeds, finally our space dreams can
| start to be realized.
| jitl wrote:
| Where are you going to get the water? What makes water mass
| cheaper to orbit compared to nitrogen mass?
| TMEHpodcast wrote:
| Closed-loop systems like on the ISS already reclaim water
| from humidity, sweat, and urine, and could be scaled up for
| larger habitats. Air works similarly: CO2 is scrubbed,
| oxygen is regenerated from electrolysis, and trace gases
| are filtered. I realize you still need an initial stock of
| oxygen and nitrogen, but isn't this a problem that could be
| solved eventually with science?
| jitl wrote:
| This is like saying "once we solve the problem, the
| problem will be solved"
| TMEHpodcast wrote:
| Now you're speaking my language! Let's get started shall
| we?
| dylan604 wrote:
| Hang out a big butterfly net and capture the dirty
| snowballs that float past.
|
| There have been lots of new releases of frozen water
| discoveries on various bodies. Typically in craters that
| pretty much stay in shadow. Water doesn't seem to be that
| scarce. It's just not as abundant as on Earth
| jitl wrote:
| Going to the moon to get water and bring it back to earth
| orbit is going to be much more expensive than sending
| water from earth for a long time.
| PaulHoule wrote:
| The image of the really big mass driver that looks like a
| train you get from O'Neill or Heinlein is obsolete.
|
| The US Navy built a 2.5km/s railgun you could fit on a
| ship. A 3.5 km/s coilgun has to look like the Paris gun
| to be practical and be able to shoot at a high elevation
| to hit Earth-Moon L1/L2 or near-Earth space. A railroad
| car worth of material per day in 1kg or so increments
| seems plausible. A radiation shield for a deep space
| station or a simulated asteroid to test mining and
| manufacturing technology might compete with terrestrial
| materials.
|
| O'Neill's students never came up with believable catcher
| and I've yet to see one I like. I guess you could get to
| LEO if you could aerobrake but it looks tough because the
| outer atmosphere is always changing and a wild shot could
| trash your target, talk about a space junk problem.
|
| The moon has at best a large glacier on it and my guess
| is Lunarians, if they could vote, would not want to
| export a gram of it but rather incorporate it into a
| circular economy.
| schiffern wrote:
| >What makes water mass cheaper to orbit compared to
| nitrogen mass?
|
| Nitrogen needs a high-pressure bottle which is wasted mass,
| whereas water you can send to orbit in thin plastic and
| fabric bags like they do on ISS.
|
| Often on ISS they're actually shipping _oxygen as water_ ,
| but still the wasted mass of water being 11% hydrogen plus
| the wasted mass of the bag is more efficient than a high
| pressure gas cylinder.
| PaulHoule wrote:
| For my baby Bernal sphere it is shipped either as LN2 or
| NH4. The large airspace needs a lot of it compared to the
| water inventory. O'Neill's published designs except for
| the Stanford torus were much worse.
|
| The water inventory of both N2 and H2O on Earth (0.2
| cubic km of water per inhabitant) is extravagant. Ceres
| is roughly 50% water (like the generic outer solar system
| or interstellar object) and we could use all of it but it
| adds up to about the mass of our oceans, and that is most
| of the water inventory the asteroid belt.
|
| I've looked at various large rotating structures up to
| the size of the Banks Orbital and concluded you could
| solve the structural problems if you could make a
| reliable journal bearing (structural parts don't need to
| be spun) that could handle the velocity difference but no
| matter what you cannot afford tall mountains or deep
| oceans.
| schiffern wrote:
| Agreed, liquid is probably the way to go.
|
| Very tempting to swap nitrogen for helium, but AIUI the
| main downsides are that the speed of sound is higher so
| air will leak out from a breach faster, and there may be
| negative effects on flammability due to helium's high
| thermal conductivity and low specific heat.
| hotshiitake wrote:
| Probably a naive question but would it possible for us to
| skim gasses from LEO for use in space stations?
| 05 wrote:
| Putting aside issues with capturing basically vacuum at
| 8km/s, by doing that you're going to lose impulse that
| you're going to have to regain, spending more mass in
| fuel+oxidizer than you gained in gathered gases, unless
| you use ion propulsion (which ISS doesn't). Also most of
| what you're going to capture at 400km is going to be
| atomic oxygen and helium, N2/N share is only a couple
| percentage points at that altitude.. [0]
|
| [0] https://en.wikipedia.org/wiki/Heterosphere
| wildzzz wrote:
| We already built LOX tanks into rockets. Just send up a
| tank of LN2. It doesn't need the strength of a bottle,
| you just need thermally insulating materials which can be
| very light.
| PaulHoule wrote:
| Starship to LEO is technologically conservative -- it's hard
| for me to believe that something like that couldn't be made
| to work. The uncertainty is that there's not a big market
| right now for launching things that size but the hope is that
| the low cost creates the market and maybe Starlink bootstraps
| it. If it succeeds as an LEO cargo hauler it can be
| successful without getting man rated or perfecting refueling.
|
| Refueling to go father is technically risky and the
| performance often not that exciting. If you aren't able to
| refuel on the Moon, Starship lands and returns roughly 3.5
| tons, not better than the Apollo LEM which a much larger
| vehicle that is tall and tippy -- landing on inner solar
| system bodies that it is covered with boulders.
|
| Now it might make sense to put a full load of cargo on it,
| leave it on the Moon and use it as living space, storage
| tanks or something, but that's not the plan right now.
| Refueling on the Moon looks tough: water on the moon looks
| like a good bet, if we're lucky we find frozen carbon sources
| at the poles or in asteroid residues on the surface [1], but
| a hydrogen-oxygen rocket looks like a surer thing.
|
| As for alternatives to local nitrogen there is: (1) producing
| it by nuclear processes which looks tough and (2) various
| other alternative breathing gases such as Argon, Helium, SF6,
| etc.
|
| [1] Not clear though if we want to spend any of those on
| reaction mass or incorporate them in a circular economy.
| Actual colonists would see it differently than flatlanders.
| (See _The Moon is a Harsh Mistress_ and _The Martian Way_ )
| dylan604 wrote:
| > The uncertainty is that there's not a big market right
| now for launching things that size
|
| Is that true? It seems like there have been the want of
| lifting large payloads that must be shrunk to fit the
| actual launch capabilities. This usually means sacrificing
| so the thing that is launched is not what was really wanted
| originally. I think the market is there and just waiting
| for the thing to work.
| PaulHoule wrote:
| You may be right. The fact is that Falcon 9 was aimed
| straight at a huge market. So far SpaceX has been
| brilliantly successful when it has focused on immediate
| commercial markets.
|
| When it comes to things like space telescopes, a cheap
| 100 tons to LEO would change the paradigm of how things
| are developed completely. When it comes to deep space
| missions that are a one way trip it's not clear Starship
| does better than something like the SLS which was cost
| optimized (see big dumb booster)
|
| The way Starship is being developed, with failure being
| very much an option, could get to LEO with cost
| optimizations. Mars is a different animal --- if takes 10
| tries to stick a landing you're going to wait 25 years.
|
| The key problem of deep space colonization or
| exploitation is the long turnaround time. I did an
| unpublished study of the problem of turning asteroids
| into solar sails and concluded that it would be
| impossible if you disn't have a physical twin in space
| near the Earth to teat anything (like fixes to problems)
| that needs testing. The problem of landing Starship
| without chopsticks could be tested exhaustively at White
| Sands, for instance.
| schiffern wrote:
| Off topic but FYI I tried to sign up for your newsletter
| from the Ontology2 homepage and got the following error
| (iOS/Safari): 403 ERROR The
| request could not be satisfied. This
| distribution is not configured to allow the HTTP request
| method that was used for this request. The distribution
| supports only cachable requests. We can't connect to the
| server for this app or website at this time. There might
| be too much traffic or a configuration error. Try again
| later, or contact the app or website owner.
| If you provide content to customers through CloudFront,
| you can find steps to troubleshoot and help prevent this
| error by reviewing the CloudFront documentation.
| Generated by cloudfront (CloudFront) Request ID:
| zte7dpy79ryEUqFA5UUBPv4Yl4t6NIL4lyHvs6yqTcdr8wCrXG5xHA==
| PaulHoule wrote:
| Thanks for heads up. That site was part of a serious
| marketing effort when I was trying to start something up
| and I haven't really thought about it in years. The home
| page made sense at the exact time I made it but is a bit
| of a non-sequitor now. I've got to get a lot of my notes
| published there.
| schiffern wrote:
| Thanks, looking forward to whatever. As a fellow nerd
| with similar interests I literally "want to subscribe to
| your newsletter" lol. Cheers.
| PaulHoule wrote:
| Immediate term you should just send me an email to get in
| touch.
| schiffern wrote:
| Email sent, thank again.
| ceejayoz wrote:
| > something like the SLS which was cost optimized
|
| If SLS is "cost optimized", I shudder to think what a
| non-cost optimized rocket would look like. One launch a
| year at $2.5B a pop?
| meepmorp wrote:
| optimized to cost a lot
| PaulHoule wrote:
| "Like SLS" in that it is a huge expendable booster, not
| "Like SLS" in terms of development process.
|
| This book
|
| https://www.amazon.com/Shuttle-History-Developing-
| National-T...
|
| has wonderful illustrations of many of the hundreds of
| designs they considered before settling on what was to be
| the Space Shuttle and also talks about late 1980s studies
| that considered various ways of putting together Space
| Shuttle parts to make different vehicles (say a big-ass
| orbiter with more engines, a bigger ET and more SRBs) The
| hope was that you could reuse the development work that
| went into Space Shuttle parts but it seemed like anything
| you made out of Space Shuttle parts was unaffordable no
| matter what you tried.
|
| You could certainly develop parts that are cheaper on a
| per unit basis but would it be worth developing them for
| the number you would make?
|
| The US doesn't really have an attractive answer to
| getting to the moon or for aggressive deep space
| missions, Starship doesn't look great. Growing up in the
| 1980s I read the "Science Fact" columns in Analog Science
| Fiction magazine and was told that NASA sold us out and
| we could have had a much more intensive lunar program but
| really the architecture Apollo used was brilliant and
| much more achievable than everything else they
| considered.
| avmich wrote:
| > The US doesn't really have an attractive answer to
| getting to the moon or for aggressive deep space
| missions, Starship doesn't look great.
|
| Starship is almost an assisted single stage to orbit
| (ASSTO), the first stage gives rather modest part of
| total characteristic velocity.
|
| This allows the second stage, Starship, to have a lot of
| delta-v. I guess it was optimized for Mars operations.
| Yes, Starship requires refueling for any flight away from
| Earth orbit, but instead it packs significant delta-v, so
| sending large payloads away from Earth - after refueling
| - becomes easier. That includes Mars, Moon, asteroids,
| the rest of Solar system.
|
| I think this makes Starship design rather good.
| boznz wrote:
| Hard challenges are good and setbacks are to be expected if
| you are pushing every limit. I would love to be on such a
| fast moving team with such a massive payoff if they succeed.
| lukan wrote:
| "(5) Colonization of Ceres dominates all other space
| colonization opportunities in the solar system because there is
| no shortage of water and no shortage of nitrogen."
|
| What about gravity?
| PaulHoule wrote:
| Rotation. You don't live on the surface but you build a
| beanstalk and build a big framework of small O'Neill's
| cylinders. See
|
| https://arxiv.org/abs/2011.07487
|
| I'd say this paper thoroughly debunks all other space
| colonization plans in comparison. For instance it is not
| sustainable to use rockets for routine transformation. The
| moon doesn't have enough volatiles. Who knows if gravity on
| the Martian surface is enough to be healthy.
|
| Even if you could take, say, Mercury, apart it would be silly
| to build a 'Dyson swarm' but rather you would build a big
| framework like that or a 'Dyson foam' (e.g. if you took
| Mercury apart and turned it into a solar collecting structure
| 1m thick you could capture enough energy to make a few tons
| of antimatter a second for interstellar travel)
| perihelions wrote:
| Ceres is very far away orbitally. It's three times further than
| Mars, but also has no braking atmosphere or gravity. If you
| send a payload to Ceres, that payload has 5 km/s of relative
| velocity that can only be zeroed out with rocket propulsion.
| (That's a lot).
|
| It's not coincidence the first Ceres orbiter was also a
| flagship prototype for advanced electric propulsion. It's a
| deceptively remote target.
| PaulHoule wrote:
| Granted. I don't see it as a Muskian "send 10,000,000 people
| and keep sending them supplies" kind of thing but rather
| "send 100 people, 1,000,000 eggs and the closest thing to a
| Drexler machine that we can make" kind of thing. The latter
| is what I think the BoM for a successful Mars colony looks
| like too.
| tim333 wrote:
| I'd imagine, given the rate of progress with AI and robots,
| the most practical would be to send robots ahead and have
| them build the infrastructure for some people to maybe
| visit later?
| jandrese wrote:
| I had a back of the napkin design that was basically a sleeve
| that fitted over Starship and could be launched into orbit.
| Those sleeves had angled ends that could then be bolted
| together in orbit to make a station with an octagon shape that
| could be spun at 2 or 3 rpm to get 1/2 Earth gravity. Obviously
| still an enormous engineering challenge, but one that I think
| is solvable using today's tech. Well, tomorrows tech, but
| nothing that requires a breakthrough in materials science or
| basic physics or anything like that.
|
| My plan was to fit the inside with huge water bags that would
| help to reduce cosmic radiation, provide thermal mass, and slow
| any micrometeorites that puncture the hull. The water could be
| launched on cheaper rockets and transferred in orbit. The water
| could also be pumped between sections to keep the wheel
| balanced. The central hub area would be more of a challenge,
| probably having to be assembled (or at least unfolded) in
| orbit.
|
| Probably the biggest downside is that you wouldn't be able to
| spin it up until the entire structure was somewhat balanced,
| which means installing things like solar panels and radiators
| in pairs and the docking bit of the central hub would probably
| need to be on bearings so it can counter rotate to be
| effectively stationary or you wouldn't be able to dock more
| than 2 spacecraft at a time. The ISS was built in sections over
| the course of decades, this would need to be built all in one
| go, which is a huge commitment.
|
| NASA's plans for two tethered stations (or one station and a
| counterweight) are probably more feasible, but much less cool.
| mr_toad wrote:
| > large amounts of nitrogen or some other inert gas
|
| You could ship liquid ammonia and then burn it to produce
| nitrogen and water.
| bryanlarsen wrote:
| Long term zero gravity experience and experiments were very
| important information for future space flight. Now we know a lot
| more about the muscle atrophy, bone loss, and vision problems
| that the author complains of. Having the first space station be
| zero-g was probably the right move.
|
| But for the second one, more information on artificial gravity
| through centripetal force makes a lot of sense.
| lupusreal wrote:
| The problem is the ISS wasn't the first station and we already
| knew zero-g fucks people up long before the ISS was built.
| Building the ISS anyway so we can waste more time studying the
| minutia of exactly how badly and quickly it fucks people up was
| a mistake. In truth the ISS exists for political reasons, not
| because it was a sound investment from a science and research
| perspective.
| bryanlarsen wrote:
| Congratulations, your alternate history has delayed Mars
| colonization by several decades.
|
| Because of the ISS we know that stays of greater than 12
| months in zero gravity have real but minor impacts on the
| human body. So 3-4 month trips to Mars in zero-g are
| feasible.
|
| If we assume they aren't, those trips would be far more
| resource intensive.
| lupusreal wrote:
| We didn't learn any of that from the ISS which we didn't
| already know from Salyut 6 and 7, and Mir. The ISS, aka Mir
| 2, hasn't taught us anything new. The reason it exists is
| because decades ago, for a few years, manned space stations
| made sense for orbital reconnaissance because putting
| unmanned cameras in space was complicated. Salyut and MOL
| were born from this transient strategic necessity. Unmanned
| recon satellites soon became practical though, so MOL was
| canceled but the Soviets carried on with Salyut because if
| there was anything they were good at, it was continuing to
| make something long after anybody else would have canceled
| it. Even when they did get recon satellites they did it
| with Vostok capsules, they never stopped making those after
| launching Yuri Gragarin in one. They just kept on making
| them because they were already tooled up for it, finding
| new excuses to keep making the same old stuff. And so it
| was with Salyut, the program was obsolete for orbital
| reconnaissance but they were already making them so they
| kept at it, turning it into a national prestige program.
| Mir was a direct descendant of it, built around the DOS-7
| module which was a Salyut module with 6 docking ports
| instead of the two on DOS-6. It never had a good reason for
| existing besides Soviet politics. (By the way, Skylab never
| had a good reason for existing either, just politics. NASA
| trying to hold onto their funding as Apollo was wound
| down.)
|
| The ISS is nothing more than Mir 2, built around the DOS-8
| module, it's a Salyut with American funding because this
| time America wanted to keep the Russian space program
| solvent to make it harder for Iran/etc to recruit that
| Soviet talent. And because NASA likes long term projects
| that require around the clock staffing because that's great
| for budgets and careers. That's why the ISS exists.
|
| Also we aren't going to Mars. Sorry. A lot of _individuals_
| are passionate about that but at an organization level
| there is no drive for it. NASA likes to use the talk of it
| for fundraising but never makes progress on it and Congress
| won 't ever greenlight it, and SpaceX uses it to keep their
| employee moral up but all they are _demonstrably_ working
| towards is being the king of launching satellites. The only
| money to be made in space is with stuff pointed at Earth.
| There is no economic case for Mars colonization. It 's not
| happening. I wish it weren't so because I'm a sci-fi junky,
| but it is what it is.
| avmich wrote:
| > We didn't learn any of that from the ISS which we
| didn't already know from Salyut 6 and 7, and Mir. The
| ISS, aka Mir 2, hasn't taught us anything new.
|
| I doubt that. ISS served in space longer than Mir and
| Salyut-7 combined, I would expect it to run more
| experiments and get more data - especially as the
| equipment is more modern and experiments are planned with
| the benefit of knowledge of the previous works.
| lupusreal wrote:
| The amount of time the station spends in orbit isn't
| relevant, the amount of time a person spends in orbit for
| an unbroken stretch is what's relevant. Three of the top
| five spaceflight duration records were set on Mir,
| including the top two (437 days and 379 days.) Nobody
| even thinks of getting close to that top Mir record
| anymore because it is already known that it fucks people
| up.
| avmich wrote:
| > The amount of time the station spends in orbit isn't
| relevant,
|
| The people on ISS were doing a multitude of scientific
| programs during that long time. That's important.
| notahacker wrote:
| There are microgravity experiments run in the ISS _other_
| than "how much does microgravity atrophy the human
| body?"
| lupusreal wrote:
| _And another thing:_
|
| We still have no idea what long term stays in Martian or
| even Lunar gravity does to a human body. We don't know
| because we have spent the past half a century fucking
| around with useless zero-g space stations instead of
| building von Braun wheels which could easily be used to
| simulate those conditions. Because forget about Mars
| colonization, merely finding the political willpower to do
| something as conceptually simple as _spinning in space_ is
| evidently impossible for us.
| bryanlarsen wrote:
| The simulation would be flawed. Von Braun wheels would
| have very significant Coriolis effects, so it'd be hard
| to distinguish whether any issues are due to reduced
| gravity or the Coriolis effects.
| lupusreal wrote:
| Bone density and muscle loss effects shouldn't be
| significantly effected by coriolis effects. Such effects
| may likely cause nausea in many people, but it is very
| likely that test subjects who can adapt to it and live
| comfortably during the period of study could be found.
| PlunderBunny wrote:
| My very rusty physics tells me that walking one way along
| the inside of the wheel would make you weigh less, and
| the other way would make you weigh more - is this what
| you're referring to? Would trying to work 'normally' in
| this kind of situation induce nausea, or make your food
| fall off your tray etc? It would be a shame if you went
| to all the effort to make a Von Braun wheel in space to
| simulate gravity, only to find that you had to stand
| still to do anything practical.
|
| (I assume the astronauts in 2001 A Space Odyssey jogged
| in the direction that made themselves weigh more, to make
| their workout more intense.)
| cubefox wrote:
| In several decades of zero-g research, they didn't even
| manage to put a few mice up to see whether they could
| successfully reproduce without gravity. Are they afraid
| of the results?
|
| It would be embarrassing if the mouse babies come out
| crippled, even if it doesn't immediately generalize to
| humans and the low-g environment of Mars.
| rich_sasha wrote:
| > Made from soft materials, like rubber and nylon, there were
| concerns that collisions with micrometeorites could puncture the
| station with fatal outcomes.
|
| I fixed many an inner tube punctures, but I'd rather not be
| blowing at glue while my precious oxygen is hissing out towards
| outer space!
| dylan604 wrote:
| Just send up a case of Flex Seal. Maybe the spreadable version
| instead of a spray on version. Not sure what zero-G would do to
| an aerosol can like that.
| craig_s_bell wrote:
| Even better: Make the entire structure out of Flex Seal.
| tokai wrote:
| I bet something like tubeless sealant could be utilized for
| automatic sealing.
| XorNot wrote:
| I mean, tapered rubber bung stoppers are a commonly used
| technology in day to day life...
| abe94 wrote:
| Great read,
|
| One question i've had is if its given that we care about making
| humans space faring, why focus on getting to new planets and
| colonisation and not instead on building the massive
| megastructures mentioned in the article as an end in itself?
| pimlottc wrote:
| > Popularised by von Braun in his 1949 sci-fi novel, Project Mars
|
| Von Braun's novel was written in 1949 but wasn't published until
| 2006. Perhaps the author means the technical appendix "The Mars
| Project" [0] which was published in 1952, which spawned a series
| of articles [1] in the popular magazine Collier's from 1952 to
| 1954.
|
| 0: https://en.wikipedia.org/wiki/The_Mars_Project
|
| 1: https://en.wikipedia.org/wiki/Man_Will_Conquer_Space_Soon!
| aidenn0 wrote:
| What about an "I" (or H if your font is sans-serif) shaped
| system? Like the Vast "stick" but with two sticks attached to the
| end. Seems like that would multiply the livable area by a much
| greater factor than it would multiply the number of launches. If
| I understand correctly the Vast is already a multi-launch system,
| so it seems like the obvious change.
| schiffern wrote:
| If you can tolerate +/- 5% gravity level (which should be
| doable), instead of a stick for the habitable area you can
| rearrange the modules into a more compact blob, which should
| reduce radiation shielding. In LEO it doesn't really matter but
| it's more important in deep space.
|
| I sometimes hear this called a "barbell" design.
| Someone wrote:
| > For example, one of von Braun's designs called for a massive 75
| metre diameter wheel
|
| That's a radius of about 5% of the length of a human body, so I
| guess we would soon find out how humans react to living in an
| environment where 'gravity' at eye height is about 5% lower than
| at toe height or do we already know something about that?
| lupusreal wrote:
| Some people would lose their lunch, but that's nothing new for
| space flight. It's just a _much_ more mellow version of classic
| carnival rides.
| Someone wrote:
| I know it's nothing vs a rollercoaster, but people don't
| regularly spend 24 x 7 in rollercoasters.
| silverquiet wrote:
| Not regularly, but there have been contests to see how long
| people will stay on a rollercoaster. Speaking from some
| experience, after you've gone around a few times, it can
| actually get rather boring.
| kevin_thibedeau wrote:
| The unitized concepts were proposed by people who didn't know the
| microprocessor, sophisticated electronic control systems, and
| compact robotics would be developed in the future. Furthermore,
| what rocket was going to launch that six cylinder monstrosity?
| Avshalom wrote:
| https://en.wikipedia.org/wiki/NERVA had already been in
| development for several years by 1961.
|
| Project Orion had been proposed as early as '46.
| Animats wrote:
| All the things worth doing in space turned out to be do-able
| without humans. Telescopes, radio relays, etc. The ISS doesn't
| really have much of a mission. Here's the list of current ISS
| experiments.[1] Many are aimed at the problems of keeping humans
| alive long term without gravity.
|
| [1] https://www.nasa.gov/mission/station/research-
| explorer/searc...
| avmich wrote:
| The was a long discussion about benefits of human space
| exploration. A comparison was made between that and basic
| science: just like the basic science doesn't bring immediate
| benefits, so do humans in space. However over long periods of
| time both could prove to be worthwhile.
| Galxeagle wrote:
| I like thinking about the ISS as primarily engineering (and
| operational) experiments rather than hard science. As a space
| platform, it's provided learning on how to contract private
| companies for space flights, and in turn, how they should
| operate, plan, etc. Or how to do internationally coordinated
| space operations. All of the work it takes to mature a new tech
| to a 7,8, or 9 on the NASA Technology Readiness Level[0] while
| Curiosity and Ingenuity and other long-distance (and JPL)
| missions focus on the hard science of 1's and 2's.
|
| That said, I too think the main value of ISS declined several
| years ago or more. Looking forward to the next generation,
| whatever it is
|
| [1] https://www.nasa.gov/directorates/somd/space-
| communications-...
| kleiba wrote:
| Quick OT question to any treckies out here: how is artificial
| gravity generated on Starfleet vessels?
| marcosdumay wrote:
| By magical techno-babble.
| Hemospectrum wrote:
| Wizards wave their hands and say something like, "Whatever,
| space is an ocean."
|
| The Expanse makes the observation that accelerating your ship
| at a substantial fraction (or multiple) of Earth gravity gives
| you that same degree of artificial gravity, only, you have to
| orient your decks the right way. Down is towards the engine.
|
| Of course, this in turn makes Star Trek (and Star Wars, and
| Firefly...) look even sillier, because flying in a direction
| perpendicular to your deck layout means you need _two_ magic
| gravity fields -- one to cancel out the engines and one more to
| give your crew a place to stand.
| actionfromafar wrote:
| To be fair, in Star Trek only thrusters etc seem to generate
| force vectors, and the thrusters seem able to accelerate the
| ship in any direction. Only the warp drive seems to fling the
| ship just "forward". But yeah, it's wizard retcon turtles all
| the way down...
| dragonwriter wrote:
| Thrusters and impulse engines seem to generate force
| vectors, and warp drive _usually_ doesn 't but the
| continuity is not very strong on that point and it is
| sometimes implied, and at one point in Voyager fairly
| explicitly stated to create accelerations (in Voyager, this
| was in reference to requiring the inertial dampeners to be
| functioning to go to warp without plastering the crew into
| a thin paste on the wall.)
| dragonwriter wrote:
| > Of course, this in turn makes Star Trek (and Star Wars, and
| Firefly...) look even sillier, because flying in a direction
| perpendicular to your deck layout means you need two magic
| gravity fields -- one to cancel out the engines and one more
| to give your crew a place to stand.
|
| Don't you just need one that does the required net change in
| gravity magnitude and direction? Of course, Star Trek
| actually has two (though I don't think the second is
| explicitly a gravity system, but it has that effect), a
| relatively steady state one that provides environmental
| gravity (gravity generators), and one that reacts rapidly to
| changing conditions to offset them for crew and other
| contents of the ship (inertial dampeners), which handles not
| only ship's drive thrust, but other externally-induced
| accelerations.
|
| Of course, Star Trek is supposed to be vastly farther from
| our current level of technology and understanding of physics
| than the Expanse.
| mr_toad wrote:
| They wouldn't need to stand if they had chairs with belts.
| XorNot wrote:
| I have no idea why people pose these questions about fictional
| properties. They're fictional. If the fiction says gravplating
| exists and works very well, then hey, there's your answer.
|
| Might as well ask why going to warp doesn't turn the crw into a
| fine paste on the nearest back wall, much like the fly that got
| fired as part of an artillery shell during the WW2 development
| of proximity fuses.
| glitchc wrote:
| The first and best place to build a permanent station is the
| moon. The wheel could spin on the surface at a very low rpm given
| the Moon's existing gravity, giving us the launchpad need to
| build and deploy a permanent space station.
|
| Until we settle on the moon, our forays into space will always be
| limited by pesky things such as Earth's gravity and atmosphere.
| apples_oranges wrote:
| Wait would this even work? Can you add moon gravity to
| centrifugal space station gravity? I can't imagine a setup
| where the wheel is always pushing inhabitants out in such a way
| that they are moved towards the center of the moon.
| avmich wrote:
| Yes, you add accelerations as vectors. Say, a centrifugal
| ring flatly lays on the Moon surface and rotates (around the
| axis of ring symmetry perpendicular to the ring plane) so
| that the artificial gravity on the centrifuge is about Earth.
| Moon gravity, about 1.42 m/s^2 , adds perpendicularly to
| that, so the total gravity is still about the Earth one. The
| level surface on the centrifuge is slightly tilted away from
| local vertical, but in essence you just added Moon gravity,
| vectorally, to the rotational acceleration.
| cosmic_cheese wrote:
| I am fully in favor of doing things on the moon, but have a
| theory that its relative convenience is actually detrimental.
| Without going into a lengthy spiel, convenience means low
| commitment, which translates into a high likelyhood of projects
| getting the plug pulled.
|
| Elsewhere, the hurdles to clear to get something started are
| higher, but once you're out there it's a lot less justifiable
| to reverse course.
|
| It could very well be true that it's necessary to settle the
| Moon before doing anything else, though, which could spell bad
| news for any endeavor involving crewed spaceflight. We might
| end up with a series of false starts on the Moon (due to events
| like funding getting pulled as a result of changing politcal
| winds) that end up going nowhere which then puts crewed
| spaceflight in a state where it's stuck in LEO perpetually.
| dan-robertson wrote:
| People begin from the premise that there should be lots of
| primates living away from earth, and then work backwards from
| there. I don't think governments should be paying so much for
| such activities.
|
| In my opinion it is not a good use of public money relative to
| other space projects, and crude missions to mars would likely
| destroy any hope of finding life there should it have existed,
| making them actively harmful.
|
| It seems sometimes that for NASA, the big goal is to have a large
| source of steady funding is the goal, and a space station is the
| best way to get that (hence the insane space station in the lunar
| mission plan). I get some vague impression that politicians like
| talking about missions to the moon or mars more than space
| stations, telescopes or probes.
| avmich wrote:
| > People begin from the premise that there should be lots of
| primates living away from earth, and then work backwards from
| there.
|
| No, people begin with interest in all things around them and
| from that conclude that being closer to them would be more
| convenient. This idea is perhaps as old as the human race
| itself.
|
| Modern robots aren't as capable as humans, so if the project is
| big enough, human involvement is reasonable.
| cubefox wrote:
| The article mentions that the inflatable Goodyear torus has
| become much more realistic since the inflatable BEAM module
| (2016) on the ISS. That one has a volume of 16m^3.
|
| But since then, Sierra Space has been working on much larger
| inflatable modules. Their latest test volume was already 285 m^3:
|
| https://www.theverge.com/2024/7/25/24206219/nasa-sierra-spac...
|
| According to the report, Sierra wants to move to testing a 500
| cubic meter volume this year. And the roadmap on their website
| lists two further habitats with volumes of 1400 and 5000 cubic
| meters:
|
| https://www.sierraspace.com/commercial-space-stations/life-s...
|
| That would already be pretty close to the 6000 m^3 von Braun
| wheel mentioned in the original article. Though Sierra doesn't
| seem to plan for creating something like the flexible Goodyear
| torus which could rotate, just pill-shaped inflatable capsules.
| Not sure whether this has technical reasons.
| PicassoCTs wrote:
| Could a automated factory melt moon regolith into ringsegments,
| which are then send into moon orbit, assembled and spun up? So
| far the problem seems to be the launch cost with heavier, durable
| materials, or m i misunderstanding the problem?
| jauntywundrkind wrote:
| It's crazy what we are doing with inflatables. Cargo ships with
| huge inflatable wing sails. The luxury catamaran MODX is bringing
| that down in size too. https://www.yachtingworld.com/news/modx-
| first-look-dual-infl...
|
| In space, NASA worked with Sierra Space to test their 300 cubic
| meter "Orbital Reef". The next go.is supposedly 500 m^3, about
| half the ISS size. Still seems way to small to spin though, I'd
| guess? Lockheed has their own inflatable hab station too.
| https://www.nasa.gov/humans-in-space/commercial-space/leo-ec...
|
| China launched and tested some kind of inflatable, just last
| fall. https://spacenews.com/china-quietly-tested-its-first-
| inflata...
|
| It seems like an obvious & amazing unmaterial leap, versus
| needing metal walls. If it works! Very fun having this history of
| rings post. Feels a little light on where we are though, what of
| promise _is_ happening!
___________________________________________________________________
(page generated 2025-07-03 23:00 UTC)