Sol System Skiing: So Amazing It’s Out of this World

By Katherine Walton and Luis Gomez Flores

As skiing evolves into a  more advanced and competitive sport, it has become a game to see who can ski in the most exotic, untouched regions of Earth. As space travel becomes more ubiquitous and climate change endangers ski resorts around the world, it is the logical next step that thrill seekers would venture into space in order to ski on other planets (or moons) in our solar system. The conditions in some of the regions in our solar system create some great candidates in the search for the best spots to ski. 

This concept is not particularly new, in fact, skiing on the moon was first floated (pun intended) by an astronaut named Harrison Schmitt. Schmitt was a geologist on Apollo 17, a manned mission to the moon that took place in 1972 (Dunbar). While bouncing on the low-gravity surface of the moon, Schmitt couldn’t stop remarking at the uncanny resemblance between moondust and snow. This story inspired us to investigate the possibility of skiing on other celestial bodies.

Individual articles may discuss skiing on the moon or mars, but few articles examine the issue of skiing on other planetary bodies in our solar system. This will be a comprehensive guide to skiing on planets and moons in Sol. As a small note, the term planet will be used in this article to refer to a general body in space. This is to minimize the occurrences of saying “planets and moons” by simply saying them together. 

Most skiers gain an intuitive sense of skiing physics without having to actually learn the mechanics behind their actions. However, in order to lay the groundwork for later discussions in this article, we will introduce and explain some physical phenomena.

Gravity: In basic terms, gravity is the thing that pulls us down and keeps us grounded. How much gravity you have pulling you down is a function of two things: how massive a planet is, and how far away you are from that planet. A more massive planet will result in stronger gravity while a less massive planet will result in a weaker gravitational pull. Since we’re only examining the gravity at the surface of the planet, we can assume that the distance needed for the gravity calculation will simply be the radius of the planet. You’re probably bored of physics at this point and want to know how this actually affects skiing. Essentially, skiers accelerate when going down a mountain because the force of gravity is pulling them downwards. Less gravity means that they will accelerate down the hill slowly, conversely, more gravity means they accelerate quicker. A skier who is used to a certain steepness when it comes to routes will need to adjust to a flatter hill if they’re skiing on a planet that has stronger gravity than Earth. The opposite is true for weaker gravity. When it comes to jumping, skiers on a planet with weak gravity can jump much higher because they don’t have as much gravity pulling them down compared with a planet that has strong gravity.

Friction:

Friction can come from a few sources and always resists your movement, which is to say, slows you down. Friction is a function of two materials coming in contact and releasing kinetic energy (movement) into thermal energy (heat). If you can minimize friction, you will lose less kinetic energy and will be able maintain your speed without being slowed down. Every material has a property called “coefficient of friction” and depends upon the material itself. If you’ve ever waxed your skis in order to go faster, then you’ve fundamentally changed the material you’re skiing on in order to alter the friction between your skis and the snow. When skiing on other planets, there is a possibility that the coefficient of friction for the surface may not be the same as snow on Earth. One effect of this difference is that skiers might experience more friction and will be slowed down. There are other unintended side effects for skiing if you’re going to another planet. For example, lower friction means that skiers won’t have as much control in their skiing: they will need to take wide turns and will take longer to stop. 

Drag, also known as air resistance and is the effect of having friction with the air itself. This is why some skiers choose to tuck in their arms at their sides and bend over. They’re reducing their drag by minimizing the amount of air (and friction) they come into contact with, allowing them to not be slowed down. If a planet doesn’t have an atmosphere, then a skier wouldn’t experience drag and wouldn’t be slowed down as much compared to skiing on Earth. Gravity can also have interesting and complex interactions with friction, which can result in unexpected effects on skiing. See the diagram and equations below to get an idea of how gravity and friction are related.

The above diagram shows a cube sliding down an incline. Summing the forces in the x and y directions would allow for us to solve for the thing we actually care about, acceleration down the hill! 

The main takeaway from this diagram is the connection between gravity, friction, and our acceleration. Since friction is a function dependent on normal force, and normal force is dependent on the gravitational constant, the force due to friction will be lower in places where gravity is lower.

Other Factors:

Gravity and friction are the main topics that will inform our ability to ski in the Sol system, There are a couple more planetary features to consider that will relate mostly to logistics. The first consideration is temperature. Modern space suits can sustain temperatures ranging from -150°C  to 120°C (Mahoney). Since the coldest region of space is only -273°C, then it becomes apparent that it’s more feasible to ski on a cold planet rather than a hot planet. In addition, some planets have very large orbital radii and will require very advanced spacecraft in order to be able to visit and more importantly, make the return trip. 

Now that we’ve gotten some of those things out of the way, we need to examine which planets are actually able to support humans. After the survivability question has been answered, only then can we move onto the question of whether the skiing would be any good. Some planets are so extremely inhospitable to humans, that a person would surely die in the process of even attempting to land on the surface, much less survive on the surface.

For survivability, there are a range of values that must be met for humans to survive. With machines and technology, these ranges grow wider, but they are not infinite. For example, a human in the vacuum of space would die without the aid of a space suit. A spacesuit is technology that will allow a person to survive in pressures much lower than they would be able to survive without a spacesuit. For these scenarios, we will assume that the hypothetical skier has access to modern technology, and perhaps even technology we do not yet have but is not outrageous to imagine. 

The following are planets we can absolutely rule out from our analysis for various reasons:

Mercury: As the closest planet to the solar system, Mercury sits very high on the planets we can rule out as a place for skiing primarily due to the fact that it is tidally locked to the sun. As one side of the planet is constantly being exposed to the candor of the sun with temperatures of up to 430°C, the other sits in cold darkness that can go as low as -180°C (Mercury). Even if there is a sweet spot in between both sides, we can’t guarantee these locations would be great for skiing. 

Venus: Venus has a size similar to Earth, which means its surface gravity is also similar. However, it has an extremely hot and dense atmosphere with temperatures averaging 452°C. Even lead would melt on the surface of Venus. The atmosphere is 92 bars of pressure, which is the result of a runaway greenhouse effect (Landis). To put that into perspective, it is roughly 90 times more pressure than Earth’s atmosphere. Needless to say, surviving on Venus would be more challenging than deciding if it’s possible to ski on the molten surface. 

Jupiter: Jupiter is a gas giant and is several magnitudes larger than any other planet in our solar system. In fact, it is “more than twice as massive as all the other planets combined.” The surface temperature is -110°C. This fact is slightly misleading, however, since Jupiter doesn’t have a surface in any sense of the meaning. If it did have a solid core under the dense layers of atmosphere, scientists speculate that it would be upwards of 50,000°C (NASA, “Jupiter”). Even if Jupiter had a surface for skiers to ski, they would most likely be taken out by the intense winds that arise due to storms. 

Saturn: Saturn is a gas giant, similar to Jupiter. As a result, it also doesn’t have a true surface. Even trying to venture to the solid core would be a journey of survival, according to NASA, “the extreme pressures and temperatures deep inside the planet crush, melt and vaporize spacecraft trying to fly into the planet” (NASA.,“Saturn”). Saturn will have similar challenges as Jupiter, making it impossible as an environment for skiing.

Uranus: Uranus has similar feasibility problems to Jupiter and Saturn, but it is not a gas giant, it is an ice giant. Nevertheless, with a temperature of -224.2°C and winds that reach up to 900 km/h, it is too inhospitable for humans to survive (NASA, “Uranus”). 

Neptune: Neptune is an ice giant, like Uranus. While also having the problem of not having a solid surface, Neptune has the most extreme winds in the solar system. Frozen methane can travel at speeds up to 2,000 km/h (NASA, “Neptune”). Any visitor attempting to find the surface in order to ski would likely not make it.

Now that we’ve ruled out the planets where skiing is off the table, we can examine the planets where we actually have a chance to hit the slopes. The first candidate we will examine for skiing is our red neighbor, Mars.

Mars: As the second closest planet to the Earth, at first glance Mars seems like a great candidate for our skiing in space endeavor. Mars is “one of the most explored bodies in our solar system” (Mars). The primary reason for all these exploration missions is to explore Mars past, as results show that Mars was “much wetter and warmer” (Mars). Mars is roughly half the size of Earth, at a radius of nearly 3,500 km and has a gravity a third as strong as Earth’s (Mars). The temperature on Mars varies and is in the range of -153°C to 20°C (Mars). While no person has been able to visit Mars physically, we’ve been able to send rovers to explore Mars. This planet is an extremely good candidate for skiing for two reasons: it has snow and it has the mountains. Surprisingly, Mars’ snow is not made out of water, but of carbon dioxide. As a result, the molecular structure is actually smaller, making the snowflakes themselves smaller. This would likely have an effect on its coefficient of friction, making the snow more slippery (Hadhazy). Due to the combination of factors discussed, it would be advantageous to have skis 

Earth’s own, the Moon: The idea of skiing in space basically originated when observing the moon when  Harrison Schmitt found a resemblance between moon dust and snow. Being the first and only celestial body humans have set foot on, the moon is ranked very high on the best places to ski in outer space. In the first image of this post, Dave Scott is seen climbing Mt. Hadley Delta. Jim Irwin, the photographer of the image, stated that it reminded him of “Sun Valley” (Dunbar) which is a ski resort in Idaho. Harrison Schmitt was so invested in skiing on the moon that he couldn’t do his job. Schmitt made a comment about wishing he had his skis with him. After that comment, Commander Gene Cernan asked Schmitt if he had photographed the area, to which Schmitt responded “No I forgot. I got interested in skiing” (Dunbar). Schmitt was daydreaming so much about skiing on the moon that Commander Cernan went to take the images himself, as if to leave Harrison Schmitt to his own fantasies. Even though the low gravity in the moon might make it harder to build up momentum and accelerate, the same low gravity would decrease the friction, making it easier to slide through the powdery surface of the moon. With the help of the right equipment, one could overcome the challenges of low gravity and be able to maneuver around the slippery moon dust.

Overall, its proximity and accessibility to the Earth makes it one of the best candidates when thinking about skiing that is both literally and figuratively out of this world. Indeed, NASA is already planning to build a “moon village” on the surface (or perhaps subsurface) of the Moon (Palaszewski 3).

Europa: Compared to Earth’s moon, Europa is slightly smaller, barely a quarter of the diameter of Earth (Europa). Since it orbits Jupiter, it sits in the outer part of our solar system, making it a very cold celestial body. Containing a surface composed mostly of “solid water ice,” and a possible subsurface ocean that might contain double the amount of water as Earth. This moon is considered “one of the best places in the solar system to seek present day life beyond Earth” (Europa).

Luckily for us, since the surface is made out of ice, we can create our own snow and use it to ski. Moreover, Europa contains hills and domes “as large as 5.5 miles across,”(Europa Ridges) making it a great candidate in our search for the best places to ski among the cosmos. Snow creation might be difficult and expensive, so our best bet is to ski on the icy surface Europa has. Due to Europa’s icy-er surface compared to the moon, the equipment necessary to ski in said conditions would be very different than one used in the moon. Such equipment would have to account for the more slippery surface, and somehow allow the wearer to get a better grip to help them turn or come to a smooth stop. Lastly, since Europa is a celestial body that contains little to no atmosphere, the suit needs to be able to protect the wearer from radiation emitted by the sun. The specifics of this will be discussed shortly.    

Ganymede: Being the largest moon in the solar system, this Jupiter’s moon is the only one to have a magnetic field, caused by its metallic iron core. Similar to Europa, Ganymede has a surface that consists mostly of ice, with the possibility of “a fair amount of rock” to be “in the ice near the surface” (Ganymede). Groove ridges “as high as 700 meters” could potentially mean great terrain for skiing, as altitude plays a big role in gaining momentum in low gravity spaces like this one. Ganymede’s magnetic field also helps protect any visitors from solar radiation, making it much safer than other regions of space. Similar to Europa, the icy surface of this moon would make it difficult for a skier to make turns, slow down, or completely stop, so our equipment has to somehow add additional friction into the equation.        

Equipment

Among the planets and moons in which it is possible to ski, all of them have a weaker force of gravity compared with Earth. As such, it’s going to be more difficult to speed up, slow down, turn, and stop. From an initial standpoint, we would have to find very high or steep hills that allow us to speed up. In the sections above, we’ve identified some candidates that would have a suitable topography for skiing. We also hinted at ways equipment could augment the skiing experience. One way to ensure that skiers are able to have control is to increase the friction on skis by increasing its coefficient of friction. This can be done through the manufacturing process itself: giving the bottoms of skis texture. This can also be done with ski skins or wax. Some waxes are specifically designed for icy conditions and would be preferable for the conditions described on Europa and Ganymede. Perhaps, future technology will enable the possibility of having skis that can enact a mechanical system to apply additional friction. Retractable spikes is an option for this mechanical system. Potentially, this could be controlled by the skier or calculated by an autonomous system. Another proposal is that skiers could wear heavy suits while skiing in low gravity environments. This would give skiers the additional friction that would help them steer and brake. This is not advisable, however, since the skier’s movement would be hindered. A heavier suit would likely turn skiing from a fun activity into a drag (literally). When considering surfaces such as the moon, where tourists would be using the dust to glide on, skis would need to be made out of a more resilient material. The small flecks of dust can actually act like sandpaper on the bottom of skis and would file them down unless they could withstand it. The natural choice is to manufacture the skis out of metal, for example, but the effect is that the skis would unfortunately be heavier than their Earth counterparts.

Summary

Wow! We’ve talked about a lot in this article. I hope you learned something new and had good fun in the meantime. All things considered, advancements in technology will not only make colonizing of other celestial bodies possible, but inevitable. Skiing on these outer planets will certainly be exotic but it likely cannot match the snow conditions that we’re used to on Earth. Most planets are extremely volatile and should not be considered as a replacement for Earth. Earth is a rare and beautiful gift that has definitely been taken for granted.

References

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Hadhazy, Adam. “Snow on Mars Is Great for Skiing, Terrible for Snowball Fights.” Popular Mechanics. Popular Mechanics, March 12, 2013. Accessed April 27, 2021. https://www.popularmechanics.com/space/moon-mars/a8808/what-snowstorms-are-like-on-mars-15207302/ 

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