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Speaker 1: Welcome to brain Stuff, a production of I Heart Radio,

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Speaker 1: Hey brain Stuff Lauren Vogel Bomb Here. Imagine that you're

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Speaker 1: inside a vehicle or other machine this spinning around so

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Speaker 1: fast that the force presses your body against the wall

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Speaker 1: or seat. As you spin faster and faster, the pressure

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Speaker 1: forcing you against the wall increases, and conversely it decreases

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Speaker 1: as the spin slows down. The weight feels just like

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Speaker 1: the force of gravity that keeps your body grounded to

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Speaker 1: the Earth. If you're like many people, your most dramatic

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Speaker 1: experience with this type of spinning forces probably from an

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Speaker 1: amusement park ride, maybe the classic rotor ride that has

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Speaker 1: produced a great deal of joy and yes, vomit since

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Speaker 1: the middle of the eight hundreds, But a handful of people,

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Speaker 1: including astronauts and military pilots, experience the same phenomenon in

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Speaker 1: a human rated centrifuge, which is a machine that spins

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Speaker 1: to produce these high G forces, which can be summarized

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Speaker 1: as forces that cause the perception of weight like acceleration,

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Speaker 1: deceleration and quick shifts and direction like on a roller coaster,

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Speaker 1: aboard high performance aircraft during high speed turns, during launches

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Speaker 1: into space, and when spacecraft's rapidly slow as they re

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Speaker 1: enter Earth's atmosphere, and like in these rotating machines, in

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Speaker 1: a very real sense, this type of rotation produces gravity,

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Speaker 1: artificial gravity to be precise. It provides weight to your body,

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Speaker 1: a weight that your bones and muscles can't distinguish from

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Speaker 1: the weight that Earth or another planet provides on account

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Speaker 1: of its sheer mass. Consequently, for decades, science fiction writers

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Speaker 1: have envisioned rotating spaceships that create artificial gravity for astronauts

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Speaker 1: during the longest phases of space missions. These phases are

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Speaker 1: when they are not extra heavy due to the ship

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Speaker 1: accelerating to build up speed or decelerating in the atmosphere,

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Speaker 1: but when they feel relatively weightless due to the craft coasting,

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Speaker 1: negating the effects of gravity. Two examples of such artificial

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Speaker 1: gravity and science fiction are the film The Martian and

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Speaker 1: the nineteen sixty eight film two thousand one, a Space Odyssey.

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Speaker 1: The Martian features an interplanetary craft, the Hermes, with a

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Speaker 1: large wheel shaped section that rotates on its journey between

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Speaker 1: Earth and Mars, and you notice that up for the

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Speaker 1: astronauts inside the Hermes is always towards the center of

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Speaker 1: the wheel. While down or the floor is the outer

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Speaker 1: rim of the wheel. In two thousand one, a Space

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Speaker 1: Odyssey space station five is a spinning station that generates

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Speaker 1: artificial gravity equal to that of the Moon's gravity. Apart

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Speaker 1: from mere comfort, there are good reasons why we need

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Speaker 1: artificial gravity on long distance space missions. For one, experiencing

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Speaker 1: relative weightlessness for long periods of time changes our bodies

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Speaker 1: in ways that could be harmful. When astronauts arrive at

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Speaker 1: their destinations such as an asteroid or Mars, or when

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Speaker 1: they return to Earth after some time in low gravity,

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Speaker 1: bones lose mineral content, meaning they soften, becoming vulnerable to fracture.

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Speaker 1: Muscles atrophy meaning they shrink and weaken. The fluids shift

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Speaker 1: toward the head and are also excreted from the body,

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Speaker 1: causing changes in the cardiovascular system in the lungs, the

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Speaker 1: nervous systems thrown out of whack, and in recent years,

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Speaker 1: space medicine researchers have found what could be permanent eye

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Speaker 1: damage in some astronauts due to the reshaping of the

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Speaker 1: eyes lenses. Add to that, research suggesting that gravity may

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Speaker 1: be required for humans to have a normal pregnancy in space,

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Speaker 1: and it seems almost like a no brainer that any

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Speaker 1: spacecraft carrying humans around the Solar System should either rotate

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Speaker 1: or have some part of the ship that does so.

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Speaker 1: Are NASA and others researching this possibility. The answer is yes, absolutely.

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Speaker 1: Since the nineteen sixties, NASA scientists have been considering the

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Speaker 1: prospect of artificial gravity by way of rotation. However, the effort, funding,

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Speaker 1: and overall enthusiasm has waxed and waned through the decades.

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Speaker 1: There was a surge in research in the nineteen sixties

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Speaker 1: when NASA was working on sending people to the Moon,

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Speaker 1: though the budget for NASA at that time was nearly

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Speaker 1: five percent that of the entire federal government, ten times

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Speaker 1: what it is today. While NASA has not emphasized research

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Speaker 1: on artificial gravity over the past half century, scientists both

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Speaker 1: inside and outside of the Space Agency are studying a

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Speaker 1: range of situations. Mice spinning in a small centrifuge aboard

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Speaker 1: the International Space Station survived with no problem, and earthbound

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Speaker 1: humans are learning how to adapt in spinning rooms. For example,

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Speaker 1: the DLR Institute of Airspace Medicine in Cologne, Germany, is

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Speaker 1: home to the DLR Short Arms Centrifuge Module one. It's

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Speaker 1: the only one of its kind in the world researching

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Speaker 1: the effects of altered gravity, especially as it pertains to

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Speaker 1: health risks that occur in microgravity, and the University of

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Speaker 1: Colorado Boulder is studying waste design revolving systems that could

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Speaker 1: fit in a room of a future space station or

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Speaker 1: moon base. Astronauts could crawl into these rooms for just

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Speaker 1: a few hours a day to get their daily dose

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Speaker 1: of gravity. But if the need for artificial gravity is

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Speaker 1: so clear, why bother with research in space or on Earth.

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Speaker 1: Why don't engineers simply get to work designing spinning ships

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Speaker 1: like the fictional Hermes. The answer is that artificial gravity

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Speaker 1: requires a trade off because all that spinning creates problems.

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Speaker 1: As on the rotor ride, moving your head while you're

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Speaker 1: spinning that fast causes nausea. It impacts the fluid in

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Speaker 1: your inner ear and any other body parts that you

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Speaker 1: move while you're in a rotating environment, and that nausea

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Speaker 1: and disorientation worsen the faster you rotate. That is, as

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Speaker 1: you increase the number of revolutions per minute or r

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Speaker 1: p ms, and the amount of artificial gravity that can

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Speaker 1: be produced depends on both those RPMs and the size

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Speaker 1: of whatever is rotating to experience a given amount of gravity,

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Speaker 1: for example, one half the usual amount that you feel

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Speaker 1: on Earth. The length of the radius of rotation, that is,

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Speaker 1: the distance from you standing on the floor to the

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Speaker 1: center of whatever is spinning, determines how fast you need

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Speaker 1: to spin. Build a wheel shaped craft with a radius

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Speaker 1: of seven and thirty eight feet that's two d and

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Speaker 1: twenty five, and you'll produce the equivalent of normal Earth

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Speaker 1: gravity known as one G, rotating at just one revolution

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Speaker 1: per minute. That's slow enough that scientists are pretty sure

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Speaker 1: that nobody would get nauseated or disoriented. Other than the

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Speaker 1: floor being a bit curved, things aboard such a craft

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Speaker 1: would feel pretty normal, but building and flying such an

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Speaker 1: enormous structure in space would entail a lot of engineering challenges.

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Speaker 1: This means that NASA and any other space agencies or

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Speaker 1: organizations likely to send people around the Solar System in

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Speaker 1: the future must either settle for a lower amount of gravity,

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Speaker 1: faster rotation that is more RPMs, or both. The Moon

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Speaker 1: has a surface gravity of about six that of Earth's surface,

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Speaker 1: which makes it a great place to research the effects

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Speaker 1: of low gravity, but there are no laboratories on the

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Speaker 1: Moon it. There simply isn't enough data to know how

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Speaker 1: much gravity humans may need for long term space missions

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Speaker 1: or in space colonies, which means more research is needed,

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Speaker 1: as is data on how much rotation humans can reasonably tolerate.

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Speaker 1: Today's episode was written by David warm Flash and produced

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Speaker 1: by Tyler Clang. For more on this and lots of

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Speaker 1: other heavy topics, visit how stuffworks dot com. Brain Stuff

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Speaker 1: is production of I heart Radio. For more podcasts to

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