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Erik Wernquist – One revolution per minute

An evening pause: A short film that attempts to visualize what it would really be like to be on a rotating interplanetary spaceship, with artificial gravity. Quite mesmerizing.

Hat tip Rex Ridenoure.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.

The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News


  • John

    That was really cool!

    With all the adverse effects of no gravity, I think humanity is just going to have bite the bullet and engineer artificial gravity one way or another.

  • Allan

    I’m surprised there is no music. No Blue Danube Waltz or anything.
    I wonder what diameter the space station would have to be for one rpm to result in one G.

  • Allan: There is music. You probably had mute on. Try again.

  • John

    Here’s a spin calculator –

    About 0.9km for 1 RPM and 1g.

    Can I interest you in 0.75g at 2 RPM and ~175m.

  • Allan

    I see the calculator. That would be 0.9 km of radius or about 1.1 miles in diameter, with a rim velocity of 210 mph. for 1G.
    The link talks about centripetal acceleration (centrifugal force) which I learned is more accurately called linear momentum, meaning any point on the spinning disc would take off in a straight line if it were set free.

    I heard the audio after playing it again. Checked everything the first time including playing another video on this site. Must have been something on my end I missed, sorry.

  • David Eastman

    Even at that size and 1rpm, some of those scenes were moving unpleasantly fast. But to go slower and maintain 1g, you have to get bigger, and have a faster linear speed. And then you’ve got more mass, which means your structure needs more strength, and you get past the limits of current materials very quickly. I’m not sure, but I think even the structure shown is past our current limits and would tear itself apart.

    One of the many experiments that I can’t believe we haven’t even tried to do yet in the 60+ years since man first went to space is to try different gravity regimes and gather data on how biology does at lower and lower values.

  • David Eastman: Yup, the key question is not whether we need to precisely duplicate a 1G environment, but whether a 0.1G or 0.2G or 0.5G might work as well to mitigate all the health problems of 0G. It is very likely (but of course unproven as yet) that a lower G will do the job.

    We just need to find out.

    By the way, it hasn’t been done because, as commenter Edward likes to say, ISS was built to do what the government wanted. The private space stations will do what their customers want, and those customers will be all kinds, with all kinds of goals. This research will be done in the coming decade.

  • Questioner

    I think I would go crazy over time from all the rapid lighting changes and all the scene rotation. As beautiful as the view of space is, you would forego in reality it for these reasons. We know the author (Erik Wernquist) of this masterpiece. A few years ago he had already visualized the colonization of the solar system by humans with another exciting video (“Wanderes”). See below. Oh no, I just saw that it was already 8 years ago. That can’t be true. Time is running and life is short.

  • Trent Castanaveras

    David Eastmen & Mr. Z, re material limits:

    We possess the materials and knowledge to be able to engineer structures identical to the one shown, and in fact much, MUCH larger. We could have done it five decades ago with the materials science then; it stands to reason we could do it presently quite handily. This concept has been around for quite awhile, and was studied by Gerard K. O’Neill in the 1970s. Jeff Bezos attributes much of his interest in space technologies and building space infrastructure to the mentorship of Mr. O’Neill, having attended at least one of his classes.

    In fact, in a bit of synergy to this post, Erik Wernquist did the introduction scene for the video celebrating Mr. O’Neil’s life. A highly recommended watch:

  • Trent Castanaveras: Just because you can do something doesn’t mean it makes sense to do it. Cost, efficiency, and profit are (or should always) be factors considered.

    If research proves that all we need is 0.3G to mitigate all negative consequences from 0G, than it will be foolish for private companies or the government to build a 1G interplanetary spaceship for exploratory travel to other worlds, or even for ordinary transportation. Thnk about buses and airplanes. Comfort isn’t the goal, getting there is.

    This doesn’t mean 1G large spaceships won’t be built. Eventually someone will build a 5-star luxury hotel that people in space will pay big bucks to visit, or use to travel between worlds, like the giant yachts the super-wealthy now buy on Earth. That however should come later, after we have spent a lot of time building cheaper vessels and made lots of profit from them.

  • Trent Castanaveras

    Excellent points! The market will and should determine our path forward.

    For example, the O’Neill concept of Island 3 visualized in the High Frontier intro is planned to house the workers (and their families) needed for building and maintaining on-orbit solar collection facilities to power Earth’s insatiable electricity demands. The materials for either facility are provided from both Lunar and asteroid mining. THOSE facilities are to be built on the back of cheap, reliable access to orbit from Earth, and then cheap reliable transport between worlds. These concepts rely on an entirely new and currently nonexistent infrastructure. There are clearly a multitude of steps between now and then.

    The fascinating part, for me at least, is that we are taking those very first steps. This vision of our future may be unfolding before our eyes in real time. Will we see a rotating station/habitat in our lifetimes? Maybe. I hope so.

    In the meantime, the question of “can/could we?” has been asked and positively answered. “Should we?” is still on the table.

    Lets watch and see.

  • pzatchok

    I would go for a 1km radius and .5 a G.

    As for windows. They are not needed and in fact a problem in large amounts. Cameras and large screens would give pretty much a similar experience for atmosphere..

  • Edward

    Another purpose I see for various gravitation levels is to acclimate or reacclimatize people for Earth gravity. A space station in Earth orbit could have a .16G level for travelers to and from the Moon, a .38G level for Martians, and a 1G level for Earthlings. Whether people born and raised on Mars or the Moon will ever be able to acclimate and withstand the 1G level is another question for research in future decades. It could be that they could stand it in wheelchairs or other assistive technologies.

  • Max

    Beautiful concept, So much open space would not be practical or advisable when unexpected meteorites can do untold damage. (In sci-fi, they can only have open spaces like this when force fields take the place of bulkheads to hold the air in)
    Glass isn’t as flexible as metal in extreme heat/cold conditions… is difficult to repair and doesn’t offer as much protection from UV radiation.
    Rather than strobing planets and sunlight as they pass the windows constantly, I think passengers would like to have a “viewing room” or observation deck for this… One with a glass floor.
    While the interior walls will show beautiful views of home or strange places that have a calming influence between entertainment options.
    If you’ve been on a merry go round, or a fast spinning entertainment ride at a fair or amusement park, then you know what to expect when experiments begin.

    As a sidenote, there are rumors they can’t find North Korea’s satellite. did it fall into the ocean?

  • Andi

    Being a math nerd, I couldn’t help but try and work it out myself:

    1 rev/min = 2 pi r m/min * 1 min/60 sec = (2pi/60) r m/sec = pi/30 r m/sec rim velocity (r measured in m)

    centripetal acceleration: a = v^2 / r = 1g = 9.8 m/sec^2

    9.8 = (pi/30 r)^2/ r = [pi^2/900 r^2] / r = (pi^2/900) r

    r = (9.8 / pi^2) 900 = 9.8/9.86 * 900 = 895m

    Sorry for boring everyone! :)

  • Doubting Thomas

    Thanks to John for pointing out the Spin Calc site.

    I have Spin Calc bookmarked to play around with various radi and RPM needed to generate 1 G for hypothetical stations and larger habitats.

    The notes on the site has some interesting references to the angular velocity which appears to begin to induce dizziness and motion sickness in individuals. This is ascribed to “inhabitants [experiencing] a head-to-foot “gravity gradient”.’.

    The site references studies which set the limit ranging from 2 to 6 RPM. It notes that many (but not all) individuals can adapt over time to higher RPMs. The calculator has a built in warning at 2 RPM. When I play around with habitats, I try to keep things at 1 RPM or slightly less. This results in fairly high radi of the structure.

    Robert is right IMO that as a mechanism for successful interplanetary travel, we should design the minimum (radi for given G level desired) needed for travel.

    My only quibble is the observation that the minimum may depend on the purpose of your trip. Experienced space pilots and crew can adapt to higher RPM (hence smaller structure radi for given G level). But if you are transporting colonists somewhere, this may be their only space trip and to keep them ready for immediate colonization tasks you may want them to avoid long term continual motion sickness.

  • Questioner

    I believe the man briefly seen in the video at 4:50 min is a representation of Isaac Asimov. Does anyone agree with this?

  • Chuck

    While technically possible from a structural materials perspective, I’d really try to avoid all the glass, given the micrometeroid and high radiation environments once outside of low earth orbit. Maybe just a special section with high-grade glass panels and retractable covers, a la Cupola.

    I can see a similar setting, but with wall-sized video panels displaying a non-rotating or much-slower rotating view, to dispense with the issue of motion sickness (at least, that induced by visual stimuli).

    The coolest thing about this is that Starship makes this vision possible in the next decade (maybe two?)! Imagine the billionaires that would drop $500K/night to stay in THAT hotel. The ultimate luxury cruise.

    Make one smaller at 0.5g, and Carnival would operate it.

    Oh, and thing HAS to have a micro-G chamber at the hub for flying. Think orbital Quidditch!

  • Doubting Thomas

    Questioner – Maybe. The close up of the face with glasses might have Asimov’s distinctive mutton chop sideburns. The silhouette after looks a bit like Asimov.

  • Edward

    David Eastman is correct that we could have been working toward these things six decades ago.

    In the late 1950s, Walt Disney helped Werner von Braun to introduce the dream of spinning space stations in Earth orbit. When NASA was formed, these space stations were one of the things that we Americans had expected it to do for us. Instead, as Robert noted, all we got was what government wanted.

    In the 1960s, Government took over all aspects of space except for many communication satellites, NASA earned a reputation for being able to do the impossible, and the public expected great things to happen in space. Stanley Kubrick expressed this expectation with an epic movie.

    The 1970s were full of expectation and anticipation. We had just reached the Moon, including walking and driving the surface. Communication satellite operators were making profits. The Space Shuttle was announced as the cheap, reliable, and frequent access to orbit from Earth that we needed to do the multitude of things in space that we dreamed of doing. Technology was our friend.

    Trent Castanaveras is right about Gerard K. O’Neill in the 1970s. O’Neill proposed space settlements that would be even larger and more useful than von Braun’s proposed space stations. O’Neill concentrated on energy production in space, because that was the large concern that decade. It is still a concern, and if ways to do it efficiently enough can be found, profits can be made in this area of production, too. Hope for the future in space reached a zenith.

    However, because profit was not the motive, the Shuttle’s capabilities turned out to be far less and its costs far more than promised. Government has little incentive to be efficient, to control costs, to maintain tight schedules, or to do anything that We the People want done. Profitable companies have incentive for all these things, and the profit is the reward for finding better efficiencies for supplying the things that people (and organizations, companies, and governments) desire so much that they are willing to pay for them.

    In the early 1980s, Robert Truax had proposed a for-profit launch company, the kind of company that would have the incentives to find efficiencies in the access to space, but government said that the Shuttle would launch U.S. payloads to space, eliminating Truax’s ability to compete or to raise capital for his proposed company. At the time, government was the virtual monopsony in space, and it had the monopoly on launches to space. Hope for the future in space waned. O’Neill’s proposal dropped off the planet, except for a small group of L-5 Society enthusiasts. Congress’s use of the Shuttle for all launches almost destroyed the U.S. launch industry, and Europe’s expensive and subsidized Ariane rockets became popular with U.S. satellite operators. It was a nadir for space enthusiasm and hope.

    In the 1990s, for-profit companies begged for access to space to fall from around $10,000 per pound to around $2,000 per pound so that We the People could profitably do far more in space than just communication satellites. Lockheed Martin and McDonnell Douglas attempted single-stage-to-orbit solutions as an efficiency through reusing the entire launch vehicle, but their dependence on government led to failures, creating a second nadir for hope. Armadillo and Kistler also attempted private space access, but funding was difficult to find because of the government monopoly-monopsony situation. At the end of this decade, government allowed Ikonos to take photographs of Earth from space, with restriction of classified regions, opening up that space industry, too.

    In the Early 2000s, two more companies tried again. Blue Origin chose suborbital access, and SpaceX worked on the promising industry of small satellites, promising because the cost of the satellite was low (increased efficiencies), and a low cost of access to space would dramatically increase the ability for profitable companies to do things in space. When the small satellite business failed to materialize, SpaceX switched to medium lift launch vehicles, where a market already existed, but the efficiency that these companies worked on were low costs through reusable boosters (increased efficiencies), similar to the attempts in the 1990s.

    It wasn’t until the 2010s, when government finally agreed to relinquish the rest of its space monopolies that we finally were allowed to get what we want from space. Launch prices came down and more than a hundred companies became interested in launching small satellites. By the end of the decade, small satellites were launching to space by the hundreds, commercial supply and payload launches became common, and we had new hope for the future in space.

    Today, in the 2020s, we have the efficiencies of low cost, reliable, frequent access to space, and the small satellite market is (please excuse the intended pun) taking off. Commercial manned spacecraft are proving to be profitable and popular. Government has lost its monopoly on space access, and it is losing its monopsony status on doing things in space. We the People are now getting more of what we want, and there are even more things that we can now afford to do, such as our own non-governmental space stations.

    And now the Vast company has proposed building Haven-1, a space station that rotates to simulate some amount of gravity. It was a long, tortuous trajectory, but we are finally approaching one of the dreams of the 1950s.

    As the IMAX movie tried to convince us a third of a century ago, The Dream Is Alive.

    If Starship has even more efficiencies (reusing the entire launch vehicle) then we will be able to afford to do even more in space, maybe even O’Neill’s space settlements. Because of the high cost of getting off a planetary surface, space colonies dramatically increase the efficiencies of moving goods around the solar system. It takes more to get off the surface of the Earth to low Earth orbit than to go from low Earth orbit to anywhere in the solar system, except Mercury. A colony in space would not have the cost of leaving Earth’s surface. That is a dramatic increase in efficiency for people to travel the solar system. O’Neill proposed that we mine the Moon for the materials to make these colonies and to make the products that they produce for the people of the Earth, increasing the efficiency of manufacturing in space. These are part of the infrastructure that Trent Castanaveras discussed.

    Increased efficiency allows reduced prices, which results in an increased demand that drives increased profit with the associated incentive for more companies to enter that market. Over the past decade or so we have watched it all happen in real time, and it continues to happen. Soon it will happen with space stations, built for less than 1/10th the cost of the ISS. What an increase in efficiencies!

    Starship has a downside, though. It is 100 tons and can carry another 150 tons. If you think it is a problem that cracks are developing in the ISS module(s) from docking Progress and Soyuz spacecraft, think of the problems and cracks from a Starship docking with ten times the force.

  • Allan

    Regarding the technical feasibility and materials for such a structure I looked up some things because it’s been gnawing at me all day so on the back of an envelope or two I came to this…

    Carbon fiber has a tensile strength of 4,000 MPa. To be conservative let’s use its yield strength of 2500 MPa which converts to 25,493 kg/sq. cm. A 2 cm diameter cable or rod of carbon fiber then could hold 80,000 kg. (rounding numbers). Given the weight of carbon fiber is 2,000 kg/cubic meter a rod or cable of carbon fiber 2 cm in diameter and 900 meters long (the radius of the 1 G rotating spacecraft) would weigh 566 Kg. If you imagine a sky hook holding the 2 cm diameter 900 meter length of carbon fiber down to (1G) Earth, You could still hang 79,000 kg. (80,000 minus 566 kg) on the end without it breaking.
    This is theoretical and doesn’t consider whatever structural design would be best.
    I conclude the classic rotating, artificial G, space wheel is easily possible and the craft could even have a
    swimming pool.

  • Jerry Greenwood

    Why do we always see these contraptions depicted as donuts? Why not two cylindrical tubes, each a couple of hundred feet long with a kilometer of cable between them? Seems more doable.


  • Edward

    Jerry Greenwood asked: “Why do we always see these contraptions depicted as donuts? Why not two cylindrical tubes, each a couple of hundred feet long with a kilometer of cable between them? Seems more doable.

    Excellent question.

    The cable would work nicely, however it lacks stiffness, so some amount of instability would quickly develop. Control would complicate things. A stiff bar or structure would help, but keep in mind that when it comes to vibration, everything is a spring, so some amount of control may still be needed. Even the ISS has various natural frequencies. It is hard to dock if the hub is not stable enough.

    Travel between the two tubes and the docking port at the hub could be difficult. A stiffening structure between the two could contain an elevator/shuttle. Could a mile-diameter space station have similar problems with stability at the hub? Yeah.

    However, I think the better reasoning for “why” is that if such a rotating space station/colony were as useful as we think, then we would desire more work space and living space. Von Braun’s model in the late 1950s included various sections for work and living. There would also be relative ease in traveling from one part of the station to another. Structurally it is fairly stable, and the hub is relatively easy to dock to and to travel to the gravitated sections (can I use ‘gravitated’ as an adjective?). (4 minutes)

    In my own head, rotating space stations have multiple levels that allow for work in a variety of useful “gravities.” Earth level is the largest, on the bottom, and would most likely be the living areas for earthlings. A Mars level would be natural for martian visitors, and early uses would include experimenting with devices for use on Mars. The same goes for a Lunar level. Then, there is the extensive de-spun free fall level attached at the hub, which extends perpendicular to the spinning section, because you want a lot of workspace in free fall. Free fall is the main purpose of having an orbital space station. Over time, we would learn which gravity level makes the most sense, and future space stations would likely focus on that particular level.

    So far, governments have only built non-rotating space stations, because that is easiest and free fall laboratories are the purpose of their space stations. They just don’t have the interest in lower gravity levels to be willing to pay the extra cost of a rotating station or the complexity of a rotating section on an existing free fall station.

    I think a better question than Jerry’s is: can we make a rotating space station that lasts long enough to repay the additional construction costs? I think this is an area that Vast is exploring with its Haven-1 proposal.

    I also imagine an inexpensive way to build a donut space station is to use modules connected end to end, so that the rim is in a hexagon, octagon, or other regular shape rather than the smooth donut shape. This would require floors that are curved with respect to the modules, but it seems doable, and relatively inexpensive. The connections between modules may be high-stress points, so this may not work well for large, high-G, stations.

    This link gives a more advanced idea than the one I describe in the previous paragraph, but it helps show that there are several ideas for rotating space stations. We have been thinking about them for six decades, and imaginations can run wild.

  • Max

    Questioner; 200 books!
    Isaac Asimov on David Letterman’s show.

    Andi said;
    “Being a math nerd, I couldn’t help but try and work it out myself:”

    Not being a math nerd, i’ve always wondered if the polar ice caps melted (containing 3% of earths water) would the ocean levels rise the 100 feet as indicated by propaganda climate change scenarios? Considering the earths diameter, and subtracting the landmass… It doesn’t seem there’s enough volume to cause the ocean levels to rise that high.

    On the other hand, knowing the volume of the ocean and the expansion rate of water when heated… How much expansion would occur if the ocean was heated by 1°?

    And a twist on centrifugal force;
    How much difference in an objects weight between the equator and Pole?
    (I knew a truck driver who freighted truck/vehicle parts to Mexico for assembly and returned with the completed units to Canada. He claimed he could be weighed coming into the United States with a 50,000 pound limit with two full tanks, but couldn’t leave the United States into Canada unless his fuel tanks were empty or he’d be overloaded.)

    Perhaps there’s a mathematical explanation to high tide under alignment of the sun and the moon, with another high tide on the opposite side of the planet against the gravity of the earth, sun, and moon which is not intuitive with current theory. (The far side should be very low tide? Antigravity?)
    And yet low tide (below sea level) occurs 90° from high tide that should be neutral or sea level… But the water recedes below sea level at 90° to the gravitational effect just like magnetism occurs at 90° to current passing through a wire. (it should be noted that the largest earthquakes in history were usually at sunrise, low tide) I wonder if objects will weigh more at low tide as compared to six hours later at high tide?
    Could this gravitational anomaly be the secret to gravity manipulation? Inertia explanation doesn’t seem plausible.

    You may also be interested in a conversation about space elevators we had a few years ago on this site.

  • sippin_bourbon

    Reminds me of the film “Passengers”.
    Not a bad movie, but not great.
    The vessel “Avalon” was kind of cool. I wish they had featured more of it.

  • Edward

    Thank you for showing your work. You didn’t bore Max, and you didn’t bore me.

    You derived it correctly from basic principles.
    There is a slightly faster way that dynamicists have:

    a = r * w^2 (equation 1)


    a = acceleration = ~9.8 m/sec^2
    r = radius
    w = (lower case omega) angular velocity in radians per second

    w = ~0.105 rad/sec (2*pi radians per revolution ÷ 60 seconds)

    solve for radius:

    r = a / (w^2) (equation 2)

    r = (~9.8 m/sec^2) / (~0 .011 rad/sec^2) = ~894 meters

    Since radians are dimensionless, they don’t show up in the final answer.

    By the Way, for any readers who are still in school: a way to tell whether your answer is wrong is to check the dimensions in the answer. If they come out to something that they shouldn’t (e.g. meters per second rather than meters), then you did something wrong.

    This is not a guarantee that you are right, however. For instance, foot pounds (newton meters) is both a torque and a unit of work or energy.

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