Senior Secondary Category Winner
Martian Dry Ice Skiing
Hsu-Lynn Lee
Telopea Park School, ACT
The sport I selected was skiing in all forms; cross-country skiing, ski jumping, Alpine skiing, and freestyle skiing. In other words, my research surrounded the general aspects of skiing on snow, rather than focussing on a particular type of skiing. After choosing the sport, I decided that Mars would be a suitable planet, as Northern and Southern polar ice caps exist there.
The principal scientific factors related to the sport of skiing, linking to Mars, are:
- providing vitals, ie. Oxygen, water
- varying temperatures
- exposure to, and strength of, sunlight
- change in gravity
- water ice vs. dry ice
A discussion of the physical conditions of the location:
Mars is similar to Earth in many ways, yet its varying features play a vital role in skiing. To begin with, the physical conditions of Mars are such that providing oxygen and water would be vital in order to sustain skiing.
Mars is also much colder than Earth and this physical condition would make skiing on Mars different from the way it is done on Earth. The temperature on Mars, although it can reach a maximum of 27C, is on average –23C. It can even get as cold as –143C at the polar ice caps, where the sport would be played. The cold climate is, in part, due to the distance from the Sun.
As briefly mentioned above, Mars’ level of exposure to the sun is less than Earth’s. This results in the sunlight on Mars being weaker than on Earth, thereby affecting the temperature; it is much colder on Mars than on Earth.
Another difference between Earth and Mars is the change in gravity. Compared to Earth’s gravitational pull of 9.75ms/s, Mars’ is just over a third at 3.71ms/s.
It is impossible for water to exist on Mars, and very likely that no liquid exists at all on the surface of Mars. The medium the skiers would use would be dry ice. The expression “dry ice” refers to carbon dioxide which exists in the solid state instead of the gaseous state. The different properties of dry ice would have a profound effect on skiing. This is because ice, which is water in solid form, starts to melt, ie assume the liquid state, when, for example, pressure is applied, whereas solid carbon dioxide changes straight to its gaseous form, bypassing the liquid state.
A basic outline of what your sport involves and how it relates to your investigation:
Skiing is basically where the person glides over the snow on two long, thin rods [skis] with the assistance of two poles. Although the sport may be played on flat surfaces, there are usually slopes to help the skier move faster. Gravity, as well as potential and kinetic energy, are involved. Different waxes are applied in different conditions to provide extra grip, or to make gliding easier. As outlined above, different physical conditions exist on Mars. Because of these differences, the factors involved in skiing would still apply there, but with different results.
A discussion of your scientific investigation, how you investigated it, any data or modelling you develop and your key findings.
I investigated my topic by researching both my chosen planet [Mars] and sport [skiing]. I found connections between the two sets of information to see how the sport would be affected by a different planet. The scenario of skiing on Mars would require the following adjustments to be made: providing vitals, ie. Oxygen, water; adjusting for Mars’ much lower temperatures; adjusting for its lower level of exposure to the sun and weaker sunlight; adjusting for its lower gravity; and adjusting for the absence of water.
In reality, humans cannot possibly survive on Mars independently, as the red planet lacks vitals such as oxygen and water. This problem cannot be easily dismissed; although it does not link directly to the sport of skiing, it must still be considered as it does affect the participants in the activity. Furthermore, we cannot imagine that humans would evolve and adapt to the new environment, and have no need for oxygen and water. The obvious solution and means of providing such necessities would be in transporting them to Mars However, even if a sufficient amount could be moved to Mars, how would it be supplied to skiers, particularly when at the polar ice caps?
‘Space suits’ commonly used in space expeditions seems a fitting solution, but these come with faults. The space suits are extremely bulky and unwieldy – skiers aim for a sleek aerodynamic form to combat wind resistance. As it is, skiers wear helmets with that same thing in mind, and assume a special crouch for that purpose. The shape of the space suit could be altered to suit the aerodynamics and reduce air resistance.
Another problem with the suit is the weight. The skier would need to carry enough oxygen to last them at least the whole race, and cross-country skiing in particular requires a long duration of time. Weight would slow them down, and skiers would want the minimum amount of oxygen needed so they would not be encumbered. An idea to provide oxygen during the race, would be adopting the same tactics as applied in motor racing. The race course contains ‘pit stops’ which allow the driver to refuel his car. Strategy and careful planning is needed to pit at the right time to gain an advantage over competitors. In the same way, skiers could have ‘pit stops’ throughout the course where they could replenish their oxygen supply. This would add another level to the sport.
Mars – though relatively small compared with other planets, such as Neptune – has a freezing climate and it is a lot colder there than on Earth. The temperature on Mars can reach up to 27C, however this is only during a few days of the year, and a few hours of those days. The temperature of the polar ice caps on Mars would be colder than this. Mars’ average temperature, not only for the ice caps, but for the whole planet, is –23C. It is known that ice cannot melt in temperatures under –20C. These extremely low temperatures are because Mars, as compared with Earth, has much weaker sunlight due to its lower level of exposure to the sun.
As discussed in the previous paragraph, Mars is further from the sun than Earth, resulting in colder temperatures and climate as well as a diminished quantity of sunlight. Thus, an alteration in the usual tactics used in skiing would need to be made. Normally, the sun would compensate for below-average temperatures – combined with black skis, the sunlight would eliminate any difficulties caused by a cold climate. The black colour of the skis accentuates the strength of the sun – black absorbs heat from the sunlight. This additional heat would melt a thin layer of water for ease in gliding. The layer is essential for speed of the skier. However, with less sunlight [ie. the Sun having a comparatively weaker effect on Mars], other methods would need to be devised to create the layer. Pre-existing methods would need to be more powerful and effective.
Gravity would play a fairly large factor if skiing were played on another planet, particularly with such a difference between gravity on Mars and gravity on Earth. Even in relation to skiing, gravity is important. Gravity is the force that acts upon the skier; it not only keeps the skier rooted on the ice, it both adds pressure to the surface, melting the ice, in addition to speeding up the skier. Pressure is required to ski – the pressure is one of the main ways of creating the thin layer of water necessary for gliding. Increasing pressure would compensate for the lessened gravity [explained in further detail in the following paragraph], however, no matter how heavy the skier, nor how concentrated the pressure were, the change in gravity would still need to be addressed. The role of gravity relates to potential and kinetic energy:
Potential energy = mass × acceleration due to gravity × height
Kinetic energy = � × mass × velocity2
According to the Law of Conservation of Mass and Energy, potential energy is also equal to kinetic energy. Therefore this new formula could be formed:
Potential energy = kinetic energy
mass × acceleration due to gravity × height = ½ × mass × velocity2
2 × acceleration due to gravity × height = velocity2
Velocity2 is proportional to acceleration due to gravity × height. On Mars, the acceleration due to gravity is one third of that on Earth. To achieve the same speed/velocity on Mars, the height must be increased threefold.
I found that possibly the largest difference between Earth and Mars in relation to skiing was the type of ice and its properties. On Earth, if more pressure were applied to ice, the ice would melt more easily. Increasing pressure may be an easier alternative to increasing heat. Tennis rackets were used to walk through thick snow, as the weight of the person divided by the greater surface area, resulted in him/her not sinking as far into the snow. If this theory was used on skis, wider skis with a greater surface area would decrease the pressure. Hence, to increase pressure, the weight should be concentrated onto a smaller surface area. Thinner, and perhaps also shorter, skis would mean that more pressure is applied onto the ice, thus assisting in its melting and in creating the liquid lubricating layer.
On Mars, the dry ice is the solid form of carbon dioxide, whereas on Earth, the ice is the frozen, solidified form of water. Dry ice can convert into a gaseous state, however, it can never be a liquid. Having some liquid in addition to the solid ice is crucial in skiing. A thin layer of water – created mainly by pressure from the skis as well as friction, temperature and sunlight – enables the skier to easily glide over the ice. However, with the nature of dry ice, it would either remain as a solid or turn into a gas – liquid carbon dioxide could not be created.
The problem of purely solid ice could be overcome. On Earth, there are times when the temperatures are so cold that despite increased pressure, the ice still would not melt. Waxes are applied to the underside of the skis for different conditions. For example, when the weather is too warm and the ice is sludgy, soft wax is used – soft wax is highly water-resistant and has a rough, slightly uneven surface which breaks the suction between the ski and snow. In the scenario of skiing on Mars, where the temperature is too cold, hard wax is used instead. Hard wax is still water-resistant, but it is also very smooth to assist in the gliding of the skis over the firm ice.
Another solution to the cold, solid ice is changing the colour of the skis. The friction from the skis rubbing against the ice creates heat. Black skis – at least when the sun is strong – absorb the sun’s heat, thus creating additional heat. However, as explained previously, Mars is comparatively further away from the sun, and it is probable that the strength of the sun’s beams would be notably weaker. The comparative weakness of sunlight on Mars removes the usefulness of using black skis on Mars.
There has been a recent scientific discovery indicating that skiers should be able to glide despite cold weather. Oxygen atoms vibrate faster on the surface of the ice on Earth, than the atoms on the inside. The quick vibration occurring at the surface is like an outer layer that, in relation to gliding, has the same properties as a liquid. Therefore, even in cold weather, the outer layer is a substitute for the thin water layer in warmer conditions.
But even though this discovery may be true in regards to Earth and the ice on Earth, it may be completely different on Mars. Earth’s ice consists of two hydrogen atoms and one oxygen atom, whereas the dry ice on Mars is made up of one carbon atom and two oxygen atoms. Both substances have oxygen atoms; the varying feature being the hydrogen and carbon atoms in Earth’s ice and Mars’ dry ice, respectively. The differing variable may negate the behaviour of the oxygen atoms in forming an outer layer by vibrating faster at the surface.
A conclusion showing the results of your investigation:
From my research, for skiing to be possible on Mars, several aspects of skiing must be altered to suit the differing conditions on Mars. These changes are to overcome the problems of: providing oxygen and water, the colder climate on Mars, the reduced exposure to strong sunlight, the weak gravity, and the use of dry ice in place of the normal ice on Earth. Although there are some difficulties that could not be overcome – at least not yet, with our current technology – minor changes could be made. The sport of skiing would not be changed drastically; the aim of skiing would still be the same, however, there would be a change of tactics and methods of going about winning the race. Aerodynamic space suits and oxygen ‘pit stops’ would provide vitals for the skiers. The height of the ski runs would need to be increased threefold in order to compensate for the reduced gravity. Strategy in regards to what type of wax to apply, as well as the shape of the skis, would change due to lower temperatures and necessity for increased pressure. Some tactics used on Earth would no longer be effective on Mars, such as the colour of the skis, as the sun is comparatively weaker on Mars. The nature and properties of dry ice would need to be further investigated to find a better and more certain solution. As long as these aspects of skiing are altered to suit the differing conditions on Mars, there is no doubt that skiing would be possible on Mars.
Bibliography
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Stars and Planets
Mitchell Beazley Publishers
London, 1980
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By Amanda Onion
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By Edward Willett
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By Tom Cull
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“New designs and materials revolutionize the world’s oldest extreme sport”
By Maia Weinstock
Mark Jacobson
http://fisicanet.terra.com.br/fisicadosesportes/
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by Sarah Schlichting
Temperature on the Surface of Mars, The Physics Factbook
Edited by Glenn Elert
Live from Earth and Mars: Temperature overview
by James E. Tillman