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Thread: Spinning Wheel Spacecraft?

  1. #61
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    Here is a proposal in three papers to use artificial gravity generated by a "linear sled", which is like a short elevator that goes back and forth. Most illustrations are too small to depict here, papers are illustrated however. PDFs are short, tho 2nd one is 2+MB.

    Artwork shows a space vehicle with two such sleds at center.

    https://www.hou.usra.edu/meetings/de...8/pdf/3082.pdf
    The Linear Sled “Hybrid” Approach for Artificial Gravity as a Countermeasure for Crewed Deep Space Gateway Missions.
    K. Seyedmadani, J. A. Gruber, and T.K. Clark.
    Smead Aerospace Engineering Sciences Department, University of Colorado-Boulder, CO, USA; Innovative Medical Solutions Group Laboratories, Inc. FL, USA


    https://ntrs.nasa.gov/archive/nasa/c...0190001171.pdf
    The Turbolift: Linear Sled Hybrid Artificial Gravity Concept - NASA Innovative Advance Concepts (NIAC)
    Phase I Final Report NNX17AJ77G, Feb 14, 2018
    Jason Gruber (PI), Kimia Seyedmadani2, and Dr. Torin K. Clark (Co-I)


    https://www.sciencedirect.com/scienc...786?via%3Dihub
    http://cdsads.u-strasbg.fr/abs/2018AcAau.152..602V
    Analysis of artificial gravity paradigms using a mathematical model of spatial orientation
    Vincent, Grant R.; Gruber, Jason; Newman, Michael C.; Clark, Torin K.
    Acta Astronautica, Volume 152, p. 602-610.
    Publication Date: 11/2018
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  2. #62
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    Quote Originally Posted by Roger E. Moore View Post
    Here is a proposal in three papers to use artificial gravity generated by a "linear sled", which is like a short elevator that goes back and forth.
    A "shake n' bake"?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  3. #63
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    Quote Originally Posted by Noclevername View Post
    A "shake n' bake"?
    See updated/revised post, one before yours.
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    Here is a second proposal for a compact-radius centrifuge that would be "launchable" to the ISS with standard module radius, if I read this correctly. Two sources, plus diagrams attached.

    The short-radius centrifuge would be used by one person (I think) at a time for a period, then next astronaut would get in. Not sure if more than one astronaut can use it, though it seems likely if balanced.

    ===

    http://cdsads.u-strasbg.fr/abs/2015AcAau.113...80D
    https://www.sciencedirect.com/scienc...344?via%3Dihub

    Combining ergometer exercise and artificial gravity in a compact-radius centrifuge
    Diaz, Ana; Trigg, Chris; Young, Laurence R.
    Acta Astronautica, Volume 113, p. 80-88.
    Publication Date: 08/2015

    Abstract
    Humans experience physiological deconditioning during space missions, primarily attributable to weightlessness. Some of these adverse consequences include bone loss, muscle atrophy, sensory-motor deconditioning, and cardiovascular alteration, which may lead to orthostatic intolerance when astronauts return to Earth. Artificial gravity could provide a comprehensive countermeasure capable of challenging all the physiological systems at once, particularly if combined with exercise, thereby maintaining overall health during extended exposure to weightlessness. A new Compact Radius Centrifuge (CRC) platform was designed and built on the existing Short Radius Centrifuge (SRC) at the Massachusetts Institute of Technology (MIT). The centrifuge has been constrained to a radius of 1.4 m, the upper radial limit for a centrifuge to fit within an International Space Station (ISS) module without extensive structural alterations. In addition, a cycle ergometer has been added for exercise during centrifugation. The CRC now includes sensors of foot forces, cardiovascular parameters, and leg muscle electromyography. An initial human experiment was conducted on 12 subjects to analyze the effects of different artificial gravity levels (0 g, 1 g, and 1.4 g, measured at the feet) and ergometer exercise intensities (25 W warm-up, 50 W moderate and 100 W vigorous) on the musculoskeletal function as well as motion sickness and comfort. Foot forces were measured during the centrifuge runs, and subjective comfort and motion sickness data were gathered after each session. Preliminary results indicate that ergometer exercise on a centrifuge may be effective in improving musculoskeletal function. The combination is well tolerated and motion sickness is minimal. The MIT CRC is a novel platform for future studies of exercise combined with artificial gravity. This combination may be effective as a countermeasure to space physiological deconditioning.

    ===

    http://news.mit.edu/2015/exercise-ar...ity-space-0702

    Working out in artificial gravity
    A combination of exercise and artificial gravity may lessen negative effects of weightlessness in space.
    Jennifer Chu | MIT News Office | July 2, 2015

    Astronauts on the International Space Station (ISS) have a number of exercise options, including a mechanical bicycle bolted to the floor, a weightlifting machine strapped to the wall, and a strap-down treadmill. They spend a significant portion of each day working out to ward off the long-term effects of weightlessness, but many still suffer bone loss, muscle atrophy, and issues with balance and their cardiovascular systems.

    To counteract such debilitating effects, research groups around the world are investigating artificial gravity — the notion that astronauts, exposed to strong centrifugal forces, may experience the effects of gravity, even in space. Engineers have been building and testing human centrifuges — spinning platforms that, at high speeds, generate G-forces strong enough to mimic gravity. An astronaut, riding in a centrifuge, would presumably feel gravity’s reinforcing effects.

    Now engineers at MIT have built a compact human centrifuge with an exercise component: a cycle ergometer that a person can pedal as the centrifuge spins. The centrifuge was sized to just fit inside a module of the ISS. After testing the setup on healthy participants, the team found the combination of exercise and artificial gravity could significantly lessen the effects of extended weightlessness in space — more so than exercise alone.
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  5. #65
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    Why hasn't anyone yet come up with an awesome plan for artificial gravity on space missions? They have, but the research is confounded by nonmatching & uncontrolled variables.

    http://cdsads.u-strasbg.fr/abs/2010AcAau..67.1090K

    A critical benefit analysis of artificial gravity as a microgravity countermeasure
    Kaderka, Justin; Young, Laurence R.; Paloski, William H.
    Acta Astronautica, Volume 67, Issue 9, p. 1090-1102.
    Publication Date: 11/2010

    Abstract: Deconditioning of astronauts during long duration spaceflight, especially with regard to the cardiovascular, musculo-skeletal, and neurological systems, is a well-recognized problem that has stimulated significant investments in countermeasure research over the past five decades. Because of its potential salutary effects on all of these systems, artificial gravity via centrifugation has been one of the most persistently discussed countermeasures; however, to date, few studies have tested its efficacy, particularly in comparison to other, system-specific countermeasures. This paper reports results of a meta-analysis we performed to compare previously published results from artificial gravity studies with those from studies utilizing traditional countermeasures, such as resistive exercise, aerobic exercise, lower body negative pressure (LBNP), or some variation of these countermeasures. Published and non-published literature involving human bed rest and immersion studies, human non-bed rest studies, and flight data were examined. Our analyses were confounded by differences in research design from study to study, including subject selection criteria, deconditioning paradigm, physiological systems assessed, and dependent measures employed. Nevertheless we were able to draw comparisons between studies that had some consistency across these variables. Results indicate that for prolonged spaceflight an artificial gravity-based countermeasure may provide benefits equivalent to traditional countermeasures for the cardiovascular system. Too few comparable studies have been performed to draw any conclusions for the musculo-skeletal system. Gaps in the current knowledge of artificial gravity are identified and provide the basis for a discussion of future topics for ground-based research using this countermeasure.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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    If you want to go big, here is a proposal to hollow out an asteroid and spin it. I have grave doubts about this without a wobble-prevention system. Artwork shows example.

    https://arxiv.org/abs/1812.10436

    Stability of a rotating asteroid housing a space station

    Thomas I. Maindl, Roman Miksch, Birgit Loibnegger (Submitted on 26 Dec 2018)

    Today there are numerous studies on asteroid mining. They elaborate on selecting the right objects, prospecting missions, potential asteroid redirection, and the mining process itself. For economic reasons, most studies focus on mining candidates in the 100-500m size-range. Also, suggestions regarding the design and implementation of space stations or even colonies inside the caverns of mined asteroids exist. Caverns provide the advantages of confined material in near-zero gravity during mining and later the hull will shield the inside from radiation. Existing studies focus on creating the necessary artificial gravity by rotating structures that are built inside the asteroid. Here, we assume the entire mined asteroid to rotate at a sufficient rate for artificial gravity and investigate its use for housing a habitat inside. In this study we present how to estimate the necessary spin rate assuming a cylindrical space station inside a mined asteroid and discuss the implications arising from substantial material stress given the required rotation rate. We estimate the required material strength using two relatively simple analytical models and apply them to fictitious, yet realistic rocky near-Earth asteroids.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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    The ESA uses a German short-arm centrifuge that could form the basis for a space-station version to induce short-term artificial gravity.

    ===

    http://cdsads.u-strasbg.fr/abs/2014MicST..26..249F

    An Innovative Short Arm Centrifuge for Future Studies on the Effects of Artificial Gravity on the Human Body
    Frett, Timo; Mayrhofer, Michael; Schwandtner, Johann; Anken, Ralf; Petrat, Guido
    Microgravity Science and Technology, Volume 26, Issue 4, pp.249-255
    Publication Date: 11/2014

    In July 2013, the German Aerospace Center (DLR) in Cologne, Germany, commissioned its new medical research facility :envihab. One central element of the facility is a new type of short radius centrifuge called DLR-SAHC 1 (formerly known as :enviFuge), which has been developed in collaboration with AMST Systemtechnik GmbH, Ranshofen, Austria. The shift of subjects above heart-level on a short arm centrifuge allows unique studies on, e.g., the cardiovascular regulation in surroundings with a high gradient of artificial gravity. Equipped with the capacity to move the four nacelles along the acceleration axis simultaneously and independently from each other, the centrifuge allows the possibility to perform up to four complex trials in parallel. The maximal acceleration is 6 g at the foot level and each nacelle can accomodate an up to 150kg payload. Additional equipment can be mounted on two payload bays with a capacity of 100kg each. Standard features of the centrifuge include a motion capturing system with six cameras and two triaxial force plates to study the kinematics of physical exercise (e.g., squatting, jumping or vibration training) under increased gravity. Future projects involving SAHC 1 will allow the development and testing of potential countermeasures and training methods against the negative effects of weightlessness in space on human physiology. Due to the centrifuge's capability to hold heavy equipment, carrying out a variety of non-human life science experiments requiring complex and heavy hardware is also fully feasible.

    https://www.dlr.de/me/en/desktopdefa...79_read-14523/
    Short-Arm Human Centrifuge (SAHC), DLR, Cologne (D) (one photo)

    https://www.researchgate.net/publica...acility_at_DLR
    The short arm human centrifuge (SAHC): A ground based facility at DLR
    Conference Paper (PDF Available) · September 2011 (many photographs)
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  8. #68
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    in short, no one at present is working on a large wheel or similar device to create full-time artificial gravity. It's all short-duration stuff that is not constantly "on" for astronauts, who will work in microgravity most of the time they are in space.

    Not sure how effective engineers will be at eliminating torque, though.

    ,
    Last edited by Roger E. Moore; 2019-May-24 at 05:20 PM.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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  9. #69
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    Quote Originally Posted by Swift View Post
    I see a lot of speculation in this thread from all sides (such as rotate-entire-spacecraft vs. rotate-just-a-part), and not a lot of references or engineering.

    Apparently, NASA has looked at this a little, but not a lot. This article from The Space Review discusses some of the arguments about even bothering with artificial gravity.
    I very much liked this quote from the paper: "Barratt noted he and his colleagues have technical concerns about spacecraft designs that implement artificial gravity. 'Astronauts fear artificial gravity. Why? We don’t like big moving parts. They break.' ”
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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  10. #70
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    Quote Originally Posted by Roger E. Moore View Post
    If you want to go big, here is a proposal to hollow out an asteroid and spin it. I have grave doubts about this without a wobble-prevention system. Artwork shows example.

    https://arxiv.org/abs/1812.10436

    Stability of a rotating asteroid housing a space station

    Thomas I. Maindl, Roman Miksch, Birgit Loibnegger (Submitted on 26 Dec 2018)

    Today there are numerous studies on asteroid mining. They elaborate on selecting the right objects, prospecting missions, potential asteroid redirection, and the mining process itself. For economic reasons, most studies focus on mining candidates in the 100-500m size-range. Also, suggestions regarding the design and implementation of space stations or even colonies inside the caverns of mined asteroids exist. Caverns provide the advantages of confined material in near-zero gravity during mining and later the hull will shield the inside from radiation. Existing studies focus on creating the necessary artificial gravity by rotating structures that are built inside the asteroid. Here, we assume the entire mined asteroid to rotate at a sufficient rate for artificial gravity and investigate its use for housing a habitat inside. In this study we present how to estimate the necessary spin rate assuming a cylindrical space station inside a mined asteroid and discuss the implications arising from substantial material stress given the required rotation rate. We estimate the required material strength using two relatively simple analytical models and apply them to fictitious, yet realistic rocky near-Earth asteroids.
    ...Why not just use the asteroidal materials to build a bigger hab? Increase the available living space and the spin diameter at the same time.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  11. #71
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    Quote Originally Posted by Noclevername View Post
    So, what I'm getting from Swift's articles is that NASA is planning to go without any spin or weight, even though they know it's a bad idea.
    No, they are planning to go because the problems are believed to be manageable and the benefits of an artificial gravity system are not worth the costs. And when I say cost/benefit, I mean not just a strict budget meaning; I mean also things like spacecraft complexity and reliability and unquantified health benefits and the benefits of human versus robotic exploration.

    I'm not the first person to say it, but spaceflight is inherently dangerous (even more so than Earth-bound life) and it is going to be that way for a very, very long time. All of it is a cost-benefit analysis and none of it is risk free. Exploration has always been a risky business.

    From my 10 minutes of googling and the articles I've linked to, I get the impression that NASA and others have actually thought about this a lot, and that it is an on-going discussion. Maybe 10 or 20 years from now, improvements in engineering or medicine will changes the dynamics of the discussion, one way or the other.
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    Quote Originally Posted by Swift View Post
    No, they are planning to go because the problems are believed to be manageable and the benefits of an artificial gravity system are not worth the costs. And when I say cost/benefit, I mean not just a strict budget meaning; I mean also things like spacecraft complexity and reliability and unquantified health benefits and the benefits of human versus robotic exploration.

    I'm not the first person to say it, but spaceflight is inherently dangerous (even more so than Earth-bound life) and it is going to be that way for a very, very long time. All of it is a cost-benefit analysis and none of it is risk free. Exploration has always been a risky business.

    From my 10 minutes of googling and the articles I've linked to, I get the impression that NASA and others have actually thought about this a lot, and that it is an on-going discussion. Maybe 10 or 20 years from now, improvements in engineering or medicine will changes the dynamics of the discussion, one way or the other.
    I do appreciate that. I just think NASA and its cognates, or rather their Budgeteers, are too timid. I'd rather go big. As you point out, the dangers will be there anyway, and we can't overcome them without a lot of experience in the field. But it's not my call, so...
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Roger E. Moore View Post
    Why hasn't anyone yet come up with an awesome plan for artificial gravity on space missions? They have, but the research is confounded by nonmatching & uncontrolled variables.

    Our analyses were confounded by differences in research design from study to study, including subject selection criteria, deconditioning paradigm, physiological systems assessed, and dependent measures employed.
    Too few comparable studies have been performed to draw any conclusions for the musculo-skeletal system.
    In other words every new researcher tries to...

    ...reinvent the wheel.

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    http://www.artificial-gravity.com/sw...c/SpinCalc.htm

    Spin-Calc, an artificial-gravity calculator in JavaScript.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    1. It's not trivially simple from the POV of the engineers and contractors who have to make such a craft.
    Any craft can be spun without the slightest modification.

    We already spin craft.

    Larger craft with require more strength - but the same can be said about bridges.

    To mangle a quote from Larry Niven: "From an engineering point-of-view a rotating ring is nothing more than a suspension bridge with no endpoints."

    Quote Originally Posted by Noclevername View Post
    2. As I've said, a spinning counterweight is already a solved problem.
    So are suspension bridges. And they don't have moving parts, and don't have to worry about pressure seals or friction.

    A counter weight is one component on of an entire engineering feat that requires a large craft to have large moving parts under pressure, in ways we have not explored well. There's a whole host of engineering problems that we haven't even begun to solve.


    This makes no sense. You seem to to be saying an engineering problem we've not yet been able to do is "already solved", yet something we are already doing - and can be done with just a push - you say is not trivial.

    Let's look in a little more detail: what engineering problems do you think we will encounter with a fully-rotating craft that you think we will not encounter for a partially-rotating craft?
    Last edited by DaveC426913; 2019-May-24 at 11:26 PM.

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    Quote Originally Posted by DaveC426913 View Post
    Any craft can be spun without the slightest modification.
    Any human can walk on hot coals. But you need know-how to avoid burning your feet.

    A counter weight is one component on of an entire engineering feat that requires a large craft to have large moving parts, in ways we have not explored well. There's a whole host of engineering problems that we haven't even begun to solve.
    Same goes for making a human rated spin craft function well.

    This make no sense. You seem to think an engineering problem we've not yet been able to do is "already solved", yet something we are already doing - and can be done with just a push - you seem to think is not trivial.
    No, I just think it's less trivial than making a whole spacecraft designed to spin at any useful speeds. (I worded my statement poorly. It's not "solved" on a human scale, just for hand tools.)
    Yes, you can spin anything. You can airdrop anything, too... once.

    Let's look in a little more detail: what engineering problems do you think we will encounter with a fully-rotating craft that you think we will not encounter for a partially-rotating craft?
    Reinforcing the whole vessel against spin would add a lot of mass. And the whole ship doesn't need it, just the inhabited compartments.
    The fuels and propellants would have to be pumped around. The entire ship would need to be mass balanced to prevent wobble. And as I said, it would need to be larger and heavier than any currently feasible designs.
    In a spinning-jenny the pumps would need to be larger and run hotter* to pump against centrifugal spin of any significant degree. Every ounce counts in space, as does waste heat. More mass, more power, more complexity.

    In freefall you just have to coax the fluids around, against spin you need to use The Force.

    *Than freefall pumps, not Earthly ones!
    There will be less weigh(t in the center), but unless your spaceship is Enterprise-sized, the spin will still have a nontrivial effect on the inner mechanisms.
    Maybe if we can cheapen up launches or use ISRU for structural materials, that will change, but using today's means it's still necessary to make everything as light, thin, and low power as possible to minimize what you have to bring up and to make heat rejection easier (all those pumps, for balance and coolant as well as propellants).
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    Having given this a little more thought, I am beginning to wonder if I have the right picture of what NCN is envisioning. (Forgive me for addressing you in 3rd person).

    In the case of a "fully-rotating" craft, the entire habitat must be under rotation. That means the engineering challenge ubsumes the entire station.

    But when you think of a "partially rotating" craft, you are envisioning the same entire habitat - but the rotating portion is entirely internal Essentially, little more than a room with a centrifuge. All pressure issues are moot since there are no rotating components that are under pressure.

    I think some of us are envisioning something more where the rotating module is large enough that is exposed to vacuum - seals, pressure and all. That is a much bigger kettle of fish than a gym with a centrifuge in it.

    Does that add some clarification?

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    Quote Originally Posted by DaveC426913 View Post
    Having given this a little more thought, I am beginning to wonder if I have the right picture of what NCN is envisioning. (Forgive me for addressing you in 3rd person).

    In the case of a "fully-rotating" craft, the entire habitat must be under rotation. That means the engineering challenge ubsumes the entire station.

    But when you think of a "partially rotating" craft, you are envisioning the same entire habitat - but the rotating portion is entirely internal Essentially, little more than a room with a centrifuge. All pressure issues are moot since there are no rotating components that are under pressure.

    I think some of us are envisioning something more where the rotating module is large enough that is exposed to vacuum - seals, pressure and all. That is a much bigger kettle of fish than a gym with a centrifuge in it.

    Does that add some clarification?

    Yes, I think so. I was mostly picturing a 2001 Discovery type design. A "Ferris Wheel" inside a bubble or chamber. Yes, I agree that an "outdoor" centrifuge would be a much bigger challenge. Even a simple weight-on-a-string would need a lot of work to make happen.
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    Quote Originally Posted by Noclevername View Post
    Yes, I think so. I was mostly picturing a 2001 Discovery type design. A "Ferris Wheel" inside a bubble or chamber. Yes, I agree that an "outdoor" centrifuge would be a much bigger challenge. Even a simple weight-on-a-string would need a lot of work to make happen.
    In a recent episode of the Twilight Zone reboot, I was pleased to see them attempt some actual science instead of sci-fi.

    They didn't Press a Button labelled Magic Gravity; they deployed a mass on a tether and spun the ship with that. It's not enough to get full gravity, but it'll make eating your dinner a lot easier.

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    Quote Originally Posted by DaveC426913 View Post
    In a recent episode of the Twilight Zone reboot, I was pleased to see them attempt some actual science instead of sci-fi.

    They didn't Press a Button labelled Magic Gravity; they deployed a mass on a tether and spun the ship with that. It's not enough to get full gravity, but it'll make eating your dinner a lot easier.
    Digesting it, too. Otherwise something always comes up.
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    *rimshot*

    I too thought the partially rotating craft would have the rotating segment exposed to vacuum. If it's internal to the craft, the engineering would be a lot easier indeed as sealing would be a non-issue. It would still be nontrivial to make this at larger diameters and while avoiding a large mass penalty (rails, double hull).

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    Quote Originally Posted by Nicolas View Post
    *rimshot*

    I too thought the partially rotating craft would have the rotating segment exposed to vacuum. If it's internal to the craft, the engineering would be a lot easier indeed as sealing would be a non-issue. It would still be nontrivial to make this at larger diameters and while avoiding a large mass penalty (rails, double hull).
    Agreed, nothing about space construction is ever going to be nontrivial!
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    The only external design I promoted in this thread (well, it was the other thread at the time) was the Nautilus-X, and I had mistakenly assumed that some of the engineering for that had been worked out.
    Going back over it, I overestimated how far along the plans were for it; seems it was really only ever a proposal with pretty pictures.

    Dang.
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    Quote Originally Posted by Noclevername View Post
    There are going to be friction losses at the axle, unless you spin the whole vessel. Which is a whole other set of significant engineering challenges.
    Would the difference in friction be that huge? Ball bearings are pretty good these days. How much savings would you gain from spinning it at half the rate?


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    Quote Originally Posted by Jens View Post
    Would the difference in friction be that huge? Ball bearings are pretty good these days. How much savings would you gain from spinning it at half the rate?
    Ball bearings don't make a pressure-seal.

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    For certain designs, the axle would not need one. The can-on-a-string could use airtight elevators along the tethers, docking to airlocks at either end (which has its own engineering challenges... as does everything in space)
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    Quote Originally Posted by profloater View Post
    surely concentric rings gives the full range of gravity simulation with for example either sleeping arrangements or exercise area at the outer 1 g radius. Rotating the whole craft seems the best solution but if it spends its whole life in space, rotating axles are possible but beware the gyroscopic torques if we want to change the orientation. Once you have axles you might consider twin counterrotating wheels. Selective gene therapy would help the occupants to tolerate microgravity so the final rotation speed might be less than 1 g.
    That is what I want.

    Outermost wheel, is equal to Earth gravity. Then comes Mars gravity, the Moons, Ceres on the interior of the hub.

    What would such a multi-hoop station look like.

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    Besides airtight seals, an external centrifuge would need cooling, air recirculation, radiation shielding, everything a current crew module needs. But on a larger scale.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  29. #89
    Join Date
    Feb 2005
    Posts
    11,383
    Like ISS, this would be built over a long period of time, with 40 SLS/Super-Heavy launches. ISS used 30-40 STS launches of only 20 tons payload.

    40 launches of 100 tons each? That builds up nicely.

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