For the first official entry of the Sports in Space series (here’s the intro post), I’d like to cover the sport of swimming. However, to understand the feasibility of competitive swimming outside Earth, we need to understand what would be different about the physical act of swimming.

When we swim on Earth, we swim in pools of water or rivers or lakes or the ocean. Besides the hydrocarbon lakes on Saturn’s moon Titan, I can’t think of any bodies of liquid outside Earth, and I think it’s sufficient to say that Titan’s lakes are cold enough (around 300 degrees below zero in Fahrenheit) that you wouldn’t want to swim in them.

With that in mind, it’s not-at-all outlandish to think that someone will eventually build a pool outside Earth somewhere. In fact, that’s basically a guarantee. All you have to do is ship water up from Earth or melt some of the solar system’s abundance of water ice. However, now we have to think about gravity. You know how on the International Space Station you see astronauts drinking floating blobs of liquid right out of the air? A pool in zero gravity would be a floating blob of water. This would be impractical to use as a pool and impossible to use for any sort of competitive swimming competition.

However, it is possible to generate Earth’s 9.81 meters-per-second-squared gravity (one g) in outer space by using the centrifugal forces of a rotating body. This means that you can rotate a spacecraft in outer space so that the inner surface of the craft could experience a force which approximates gravity. An O’Neill cylinder or any number of other proposed spacecraft designs could do this very well.

But could you have a swim meet using a pool on a rotating spacecraft? Well, maybe, but it would be somewhat different than swimming here on Earth. Artificial gravity generated by rotation needs a curved body so that the surface you want to generate an artificial gravity on may rotate around a central point. Unfortunately, this means that the surface would have to be curved. Due to how this rotational gravity would work, the water in any pool you made would also be curved so that the surface of the water has roughly the same angle arc about the central axis of rotation as the curved bottom floor of the pool and the spacecraft as a whole.

I know that’s hard to envision. The pool would be curved and contained within a rotating body. The gravity would actually be stronger in the bottom of the pool than the top of the pool, but any significant amount of gravity (even 5% of Earth’s) should be strong enough to keep the water from floating off. A swimmer inside the pool would not feel as if they were rotating; they would just feel the centrifugal force of “gravity” being exerted on them.

With all this in mind, a swim meet in outer space’s only limitation would be the curvature of the pool. You could get a pool to have Earth’s gravity, but it would take a very large spacecraft or space station in order to have the curvature diminished enough to make the swim meet seem like it is taking place in a normal Earth-bound pool.

For smaller spaceships, a new type of swimming competition may evolve which has competitors swimming in noticeably curved lanes. The swimmers would feel as if they were constantly swimming upwards. Instead of merely lifting their heads above the water to take a breath, they may have to lift their heads up and pull them slightly backwards to compensate for the curvature of the water. Doing flips at the end of the lane may prove problematic since the wall would not be perpendicular to your direction of travel. Even with all these difference, I think some sort of swimming competition would be possible.

The idea of a swim meet in space becomes much easier to deal with if your pool is situated on a planet or a moon. Since Mars will almost certainly be colonized in the near future, let’s use it as an example. Mars has around 37.6% of Earth’s gravity. Pools on Mars could be made nice and flat like they are here on Earth. You could have nice straight lanes, and you could do your flips just like you would here on Earth.

Martian pools would likely be underground to protect from radiation, avoid dust storms, and make having facilities with breathable air easier, but those pools would look no different on the inside from any indoor aquatic center here on Earth, besides the lack of blue skies peeking through the high windows. In fact, I don’t think anything would stop you from having a swim meet on Mars. With Mars having less gravity than Earth, swimming ought to be less demanding on the body than it would be here on Earth, but the actual act of swimming shouldn’t be different at all.

So if you were wondering whether or not swimming will happen in outer space, fear not! Swimming outside of Earth is entirely possible. Future system-wide Solar Olympics competitions may have a significant home-pool advantage depending on whether Earth or Mars is hosting, but the ancient sport of swimming will be the same as ever.