Posted in science

How does artificial gravity work?

As a self-confessed lover of sci-fi, something that has always intrigued me is the presence of artificial gravity aboard vessels such as Star Trek’s USS Enterprise and the Death Star. According to the website Memory-Alpha, the USS Enterprise and other Starfleet vessels use ‘gravity plates’ to get around the issue, and in the Star Wars universe the use of ‘artificial gravity generators’ is widespread. Alas, as the elements required to make either of the aforementioned devices are fictional, we cannot recreate the technology for our own spacecraft.

Seeing as we are not yet as technologically advanced as our fictional counterparts, the only way to simulate the effects of gravity (at the moment) is by using centripetal force, much like that experienced on some types of vintage fairground rides such as ‘The Rotor’ and the ‘Gravitron’ (they’re the ones where the floor drops out from under you and you stick to the wall). This works incredibly well when applied to something as small and uncomplicated as a fairground ride, but what happens when you want to scale it up to the size of a space station? Will the concept still work? Well, worry not, for that is what we are about to find out (after a quick whistle-stop explanation of centripetal force so that we’re all on the same page).

Centripetal force is often described as ‘a force which acts on a body moving in a circular path and is directed towards the centre around which the body is moving’ (thanks Wikipedia.com). In other words, any type of motion in a curved path represents accelerated motion, which in turn requires a force directed towards the centre of the curved path. In the case of artificial gravity, it would be this force that would mimic the natural pull of the Earth and thereby stick everything to the floor. That being said, the ‘floor’ would no longer be pointing vertically downwards – due to the nature of centripetal force, everything would be sucked towards what would stereotypically be described as the wall (if everything were stationary). Essentially, everyone would be walking parallel to the ‘floor’ around the inner wall of the ship (imagine a sideways hamster wheel and you’re on the right track).

So, in theory, we do have the method to facilitate the production of artificial gravity. However, as with many things, it is easier said than done. In order for the centripetal force to match that produced by the Earth’s gravity, any potential spacecraft would have to spin unrealistically quickly. Actually, that being said, it isn’t entirely true – the rate of rotation would be proportional to size, and therefore if the ship was massive enough then it could slow the minimum speed to a more manageable pace. Again though, this solution has its own issues. In order for the speed to be sufficiently slowed, the spaceship would have to rival the Death Star in size. This would be hugely expensive to build, seeing as we would be unable to launch anything of that sheer gigantic-ness. Each component would have to be launched from Earth and assembled in situ (i.e. the entire construction would be ludicrously expensive). Along with this, the nauseating rotation of the ship would mean that windows would be an impossibility in order to avoid crippling motion sickness.

I can’t help but conclude that, at this point in time, the construction of a spaceship with artificial gravity is rather fanciful. That doesn’t necessarily mean that the technology/resources/insanely rich person with limited common sense won’t come along and make it reality, but for the time being we are still destined to float around unfettered in the great chasm of space. So, in answer to my original question, artificial gravity really doesn’t work.

Tabitha Watson

(photo cred: starwars.wikia.com)

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