Skiing and Space Diving on Other Worlds

What will be the athletic disciplines undertaken by space colonists when they go outside their habitation modules into the hostile vacuums and atmospheres of outer space? In the previous posts in this series (part 1, part 2), we have explored the activities that may be popular in a zero-g chamber or low-g centrifuge attached to a space station or space habitat; here we will go through some sports, hobbies, or disciplines that may be popular outdoors.

Space Diving: Falling into the Sky

“Space diving” is one possibility that is sometimes seen in science fiction or speculation about our real world future, representing an extension of skydiving from the realm of the lower atmosphere to the upper atmosphere or even outer space itself. Skydiving from actual outer space (beyond the Kármán line of 100 km) has never been accomplished, but several dives have been done from well above the Armstrong limit (18 km), where water can no longer remain liquid and pressure suits are required, conditions not much different from outer space in terms of human life support.

The most famous early ultra-high-altitude skydive is Joe Kittinger’s in 1960 where he jumped from 31 km. Yevgeni Andreyev in 1962 jumped from only 21 km but had a longer time in free fall than Kittinger. Both records were only surpassed in 2012 when Felix Baumgartner jumped from 39 km; Baumgartner, in turn, was quickly surpassed by Alan Eustace in 2014 who holds the current record at 41 km. Eustace was in free fall for 4 minutes 27 seconds during his dive, and reached a maximum speed of 822 miles per hour, joining the rarefied club of those who have broken the speed of sound without a vehicle.

The reason such high speeds are attained is that terminal velocity, the speed which air friction drags you down to as you fall, becomes higher as air becomes thinner, and air in the stratosphere, where these men were diving from, is thin indeed. The supersonic velocities possible, as well as the experience of the free fall and arrival on Earth, should prove very attractive to a great many people as spaceflight becomes more common. If this is to happen, it would likely first manifest itself in stratospheric Kittinger-style jumps becoming more common, followed by the pioneers expanding up past the Kármán line, presaging space diving becoming in the future as common as skydiving is today.

Of course, none of this helps the denizens of outer space acquire a new hobby or extreme sport. Why? Because all of these jumps are made from a ground-launched balloon which floats upward to the desired altitude. This is for good reason, because any space station or spaceship in low Earth orbit speeds along at around 17000 miles per hour relative to the ground and air. If someone were to dive from, say, the International Space Station the high speed through the atmosphere would cause such friction that the diver would be burned to a crisp. This is the same mechanism that causes meteors to be easily visible, as they enter the atmosphere with similar velocities, and also necessitates a heat shield on re-entry vehicles. One could probably design a heat shield suitable for one man in a spacesuit, but the experience wouldn’t be very fun for anyone, aside from perhaps a few daredevils.

So “straight” space diving is out as far as jumping off from any orbital space stations or ships is concerned, but there is another possibility, which I have taken to calling “cold entry”. Instead of using air friction to slow you down, as is done today, rockets could be used while in orbit to slow velocity down to levels acceptable for atmospheric travel. For spaceships, this could be used to slow speeds from orbital speed (Mach 27) down to the Mach 2-5 range that supersonic planes travel in without much trouble. This would be particularly useful for spaceplanes, since heat shields would no longer be necessary. The reason this method isn’t used today is that the delta-v required to do this is almost as much as what is required to get into orbit in the first place, which takes fuel, around twice as much (the fuel needed to accelerate to orbit plus the fuel to decelerate from orbit). Lugging twice as much fuel up at a $10000 per pound launch cost makes no sense when you can use the atmosphere to brake without using any fuel.

Where it starts to make sense, though, is when launch costs are much lower, so that the cost of needing to make a complex heat shield becomes higher than lugging up simple raw fuel. This may be more likely to occur in a context of a society based in free space, where the cost to get the fuel needed to decelerate to orbit is very low compared to Earth, since they wouldn’t have to go up a gravity well, and highly complex engineering is just as complex and costly as on Earth, if not more so, if there isn’t as much of a population base to support specialists in these fields. A society based in outer space that also has low launch costs compared to today may make extensive use of cold entry for its atmospheric vehicles.

This is the same context where space divers would come from that are not based on Earth. This cold entry technique makes much more sense for space diving than it does for vehicles anyway, since the experience of falling to Earth is far more enjoyable without you being ensconced in plasma for most of the trip.

So, space divers that start from low orbit would likely start out with a rocket pack big enough to lower their speed from orbital all the way down to a low speed (ideally zero) relative to the ground. This burn at a constant deceleration of 1g would take around 37 minutes and cover 6000 kilometers or so of distance. After the burn is completed the rocket pack is jettisoned, and the space diver floats down the remaining few hundred kilometers much like a skydiver does today, goes supersonic in the upper atmosphere followed by being drug down to subsonic speeds further down, and pulls his parachute at low altitudes, making a happy landing on the Earth’s surface.

With such long free-fall times, greatly exceeding those of Kittinger, Baumgartner, and Eustace, the same sort of zero-g sports mentioned in my previous two posts could be played, albeit perhaps in condensed form if the normal game length is long, with the surface of the Earth growing closer with every passing minute. This may be a popular pastime among space colonists, and perhaps even more so among Earthlings, as it would likely be the way to experience space sports that is the closest to home, the lowest cost, and the shortest trip time.

The same principles apply to other planets as well, with Mars perhaps being the most obvious, and the sheer exoticism of the red planet, combined with its relative proximity to Earth (which will remain the human population center throughout the near future) may make it disproportionately popular as a space diving and skydiving destination. Titan, by far the outermost and coldest planetary-mass object with a solid surface and an atmosphere, will likely also prove very popular for space and sky diving. Venus, although often thought of as hellish, hosts arguably the most Earth-like environment in the solar system outside Earth in its upper atmosphere (at 55 km the pressure, temperature, and gravity are all similar; the only hitch is no breathable air), and its thick atmosphere would be very suitable for space diving and sky diving. The only real problem is that if there is no vehicle or floating platform to land on or you miss your target you might be in for a one way trip unless you have some form of propulsion with you. The same caveats apply to Jupiter, Saturn, Uranus, and Neptune.

Skiing on Alien Powder

The airless moons of these gas giant planets, and many dwarf planets in other parts of the outer solar system, may provide another draw in addition to the space and sky diving available on larger worlds in their regions: winter sports. Skiing, snowboarding, and the like in the outer solar system is not something often considered when worldbuilding science fiction settings or speculating about the future, despite the fact that at least some of the ice worlds would actually be quite suitable for it. A 2011 article points out that according to research based on Cassini data there is strong evidence that the fine ice crystals from Enceladus’s famous plumes would, to some extent, be pulled down to the surface, forming a blanket of fresh show. This precipitation is extremely slow by Earth standards (millions of years to build up a few hundred feet), but since erosion on an airless world is also slow there may well be a blanket of fine powdery snow all over the moon, albeit varying widely in thickness by region.

This snow would be very ski-able, as each crystal is only about a micron across, finer than talcum powder, finer stuff than anything you’ll see on Earth. Images from Cassini reveal that this layer of fine powder is hundreds of feet deep, once again beyond anything terrestrial. The fine snow that falls steadily would likely be too fine to be directly seen by the human eye, and would likely look more like a light fog, with the ice crystals creating halos around Saturn and other moons in the black sky. Terrain on Enceladus is certainly hilly enough to harbor many downhill ski slopes, and fractures exist that would be very suitable for ice climbers or practitioners of more exotic ice sports. Snowmobiling would also be very viable as a sport in such environments.

The only potential show stopper is the fact that gravity is only one percent as strong as on Earth, meaning a skier would only be pulled down a hundredth as much as they would on Earth, meaning that a vigorous skier may spend more time gliding over the snow than actually skiing on it. The flip side, though, is that any snow that is cut up by skis or snowboards would proceed to a far higher altitude at a much slower velocity, likely being more visually spectacular.

Other ice planets and moons may also be suitable, though skiers and snowboarders will have an easier time than skaters, as this 2010 article explains. Skating works best when there is a thin layer of water under the skates generated because of friction and pressure, but water sublimes rather than melts on these airless or thin-air worlds, making skating more difficult even where there is smooth ice. On Europa, there isn’t the sort of snow there is on Enceladus but the native ice is ground up enough by impacts and the like that it should be similar to snow and thus suitable for skiing, and not so suitable for skating. Many ice worlds have naturally occurring half pipes over much of their surface that would make a paradisaical environment for snowboarders.

On Mars, on the other hand, the ice caps there more resemble frost than snow, so skating should be easier than skiing or snowboarding, though the same considerations apply with regard to no liquid water. One NASA scientist speculates that roller skates may be easier than ice skates on the Martian ice caps, though more research and ideally real world experience is needed before we know for sure.

Speaking of real world experience, although it isn’t that widely known, humans have (sort of) skied on other worlds before, namely during the Apollo missions. Moon dust, and likely dust on similar terrestrial worlds (such as Mercury), is extremely fine and abrasive compared to anything on Earth. This makes the lunar surface dusty, being roughly comparable to sand on Earth, so the same techniques used for sand skiing should work on the Moon. Harrison Schmidt swung his arms and legs cross-country style during Apollo 17, and believes that downhill techniques would work very well on the Moon, especially on crater slopes. He adds, however, that the abrasive nature of moon dust means any equipment would have to be very rugged to survive such extensive high-speed contact. On planets like the Moon or Mercury, the same sort of sports we see in sandy regions of Earth might be popular, from sand skiing to the sports based on dune buggies; indeed the Apollo rover itself resembled a dune buggy.

A Literal Space Race

Vehicles have myriad uses in space; indeed every single environment humans inhabit in outer space could be thought of as a vehicle, a line of thought that has even been extended to our home planet, in the form of “Spaceship Earth”. Smaller vehicles comparable in size to automobiles or private airplanes could be used for sporting purposes, in the same way we have car races and air races on Earth today. A straightforward point A to point B race based on speed may be boring in the vacuum of space where there is less uncertainty about the outcome, except if it were experimental vehicles that haven’t been tested yet. If hot-rodding mass-market personal spaceships becomes common this may be a popular sport to participate in for space colonists. Races between cutting-edge vehicles that aim to set new records for speed may be popular to watch.

More popular still may be a race based on maneuverability rather than raw speed, or some combination thereof, in the form of creating a course in outer space, perhaps through the use of marker buoys or in some tight confines actual solid obstructions (like a pipeline or net), for spaceships and their pilots to maneuver through. Regions that have recently experienced an asteroid collision may also be popular sites for spaceship racing, as the collision debris field would be a dangerous and unpredictable environment to maneuver through. Another possibility for more cutting-edge or wealthier denizens of space once single-stage spaceplanes become available (which is likely in the 21st century considering how Skylon is going) would be incorporating atmospheric entry and flight into the space race, creating a more complex environment over the course of the race.

Playing Polo with Spaceships

A sport aside from racing that could be done with spaceships would be an equivalent of polo. Polo, which is played on horseback, involves a player navigating around a large field and attempting to hit the ball with a mallet into a goal. The sport of auto polo, somewhat popular in the early 20th century, replaces horses with cars but is otherwise very similar. Horses could also be replaced with personal spaceships, which could use a robotic arm, operated by each ship’s pilot, to swing a mallet to hit the ball. Being outside of a centrifuge there would obviously be zero gravity, so goals could be structured in a more three-dimensional fashion. The goals could also be attached to some players’ vehicles or move around autonomously of any of the players. The ball could have a mechanism to return to the playing field (or playing space in this instance) if it’s knocked too far out of the area, as otherwise it will just keep going and become a hazardous piece of space junk.

Another variation that is possible if one wishes to leave the shirt-sleeve environment would be to have the players compete in spacesuits with open-cockpit vehicles that would resemble a chassis with rocket thrusters attached, similar to the bare-bones open-cockpit cars used eventually in auto polo.


Once again, we see even more zero-g sports, hobbies, and athletic disciplines that would be possible in parts of the solar system other than Earth. In this post we see some possibilities for sports and athletic endeavor in free space outside of a space station zero-g chamber or artificial gravity centrifuge, the environment explored in the previous two posts. Many interesting sports are also possible in a near-future setting on planetary surfaces and in planetary atmospheres across the solar system, perhaps with winter sports having the greatest amount of surface area amenable to them compared to any other category.

This is a fruitful and productive area for any worldbuilder, artist, futurologist, or author to explore that is interested in a realistic near future solar system setting, as it has the potential for compelling story premises with interesting characters to act them out, yet compared to its potential is severely underused. Even those who are not remotely space fans will be fascinated by this sort of setting. If you’re interested in the premise of this series of posts and are looking for a place to leave your mark on near future hard science fiction or futurological speculation, look no further.

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