Science

Artificial gravity: definition, future technologies and research

Artificial gravity is the creation of an inertial force in a spacecraft to simulate the force of gravity. This concept is often seen in sci-fi shows such as Star Trek, but is not limited to them. Researchers are currently working on methods to create artificial gravity in space.

The creation of artificial gravity would not only make the next era of space exploration easier by making tasks easier, but would also be critical to potential space tourism.

The effects of microgravity in space can actually be harmful to humans, so when we look at longer crewed missions, including to Mars, artificial gravity could be essential to the health of our astronauts.

Related: Is the origin of dark matter gravity itself?

Creating artificial gravity

In his 1905 theory of special relativity, Albert Einstein wrote that gravity and acceleration are in fact indistinguishable. This means that in a rocket traveling at 31.19 feet per second (9.81 meters per second) squared – the downward acceleration of gravity here on Earth – the astronaut will feel like his body is chained to the floor, as if on his home planet.

The problem is that you can’t always accelerate at that speed in space, especially on an orbiting space station. Fortunately, there is more than one form of acceleration, and by using centrifugal force, we can create something equivalent to gravity on Earth.

One possible way to create artificial gravity in space is to use a technology called the O’Neill cylinder. Named after the physicist who proposed them, Gerard O’Neill, it consists of a pair of massive cylinders that rotate in opposite directions, allowing them to constantly point towards the sun, replicating gravity.

Jeff Bezos, owner of the space company Blue Origin, proposed O’Neill’s cylinders as the basis for floating space colonies, allowing trillions of people to live in orbit.

In addition to being far from any practical application, 20 miles (32.2 km) long and 4 miles (6.4 km) in diameter – designed to accommodate several million people – O’Neill cylinders are too large for most applications of the smaller size. than colonies in space.

Researchers at the University of Boulder in Colorado have a proposal on a smaller scale – rotating systems that could fit inside the spacecraft.

A test of centrifugal force that could allow astronauts to briefly return to Earth’s gravity. (Image credit: University of Colorado Boulder)

While this won’t provide artificial gravity for an entire ship or station, it will allow space travelers to retreat to a specific area and spend some time experiencing a more Earth-like gravity field.

The system also uses centrifugal acceleration, replicating a 1G gravitational field — the same as on Earth — with astronauts lying on a centrifugal short radius to rotate quickly.

However, rotating astronauts may not be the ideal solution. Anyone who has ridden teacups too many times can tell you that this method has its health implications.

Another potential artificial gravity construct is a long, stick-like rotating vehicle about 328 feet (100 meters) in diameter with a nuclear reactor at one end and a crew compartment at the other for travel to Mars. However, they had technical problems preventing their application.

Impact of microgravity on health

Karen Nyberg having her eyes tested

NASA astronaut Karen Nyberg uses an eye health test device that can be affected by microgravity. (Image credit: NASA)

Creating artificial gravity could be key to protecting the health of astronauts on long-term space missions. For five decades, NASA’s Human Research Program (HRP) has studied the effects of microgravity on the human body.

They found that, deprived of Earth’s gravity, load-bearing bones lose an average of 1 to 1.5% of mineral density every month of space flight. Muscle mass is lost faster in microgravity than on Earth.

In addition to these factors, during spaceflight, fluids in the human body can move upward, putting pressure on the eyes, which can lead to vision problems.

Space hotel Voyager

space station illustration

Visualization of the rotating Voyager station, which will support scientific experiments and also function as a “space hotel” for tourists. (Image credit: Orbital Assembly Corporation)

The Voyager space station is a planned spinning wheel space station with construction due to begin in 2025. Voyager, pioneered by the Orbital Assembly Corporation (OAC), will differ from the International Space Station in two key ways; it will be open to the public and will have artificial gravity.

A space hotel launched into low Earth orbit would spin fast enough to create artificial gravity for 400 passengers. If the station is completed as currently planned, it will be the largest man-made structure ever put into orbit.

The first steps of the project will include building a prototype gravity ring to improve the viability of artificial gravity in space. A ring with a diameter of 200 feet (61 meters) would generate a gravity equivalent to about 40% of Earth’s, or about the same as that of Mars.

Additional Resources

For more information on artificial gravity, check out Artificial Gravity by Gilles Clément and Angie Buckley. Check out other artificial gravity projects at Orbital Assembly Corporation (OAC).

Bibliography

  • NASA, Artificial Gravity, March 2021
  • NASA, The Human Body in Space, February 2021
  • Theodore W. Hall, “Artificial Gravity in Theory and Practice”, 46th International Conference on Ecological Systems, July 2016
  • National Space Society, “O’Neill’s Cylinder Space Settlement”, accessed May 2022.
  • National Space Society, “Stanford Tor Space Village”, accessed May 2022.
  • Orbital Assembly “Experience Space Gravity Here”, accessed May 2022.
  • Nicholas Martelaro, “Powering the Stanford Torus”, Stanford University, May 2017

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