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air we breathe is composed of a mix of gases. Scientists have conducted
experiments that tell us how much of each type of gas is in the air.
With this information we can create Table #1 and Pie Graph #1: The
Gases in the Earth’s Atmosphere.* *Authors Note: The following might appear in a pop-up window. Our Pie Graph #1 represents a “perfect” mix of air. Pie Graph #1 is a good snapshot of a “perfect,” or scientifically, standard mix of atmospheric gases. Can we ever isolate the exact mix of air that is in our pie chart? Probably not. From day to day, the atmospheric content can change as the weather and temperature changes. The air’s mix of gases also changes with pollutants from traffic, factories, and power plants. Man’s activities can change the gases in the air, both inside and outside. Gases in the Earth’s Atmosphere Take a moment to look at and think about Table #1 and Pie Graph #1. Then answer these questions: • The Pie Graph #1 tells us that our air is a mix of different gases. • What are the three “major” gases of the atmosphere? • Why are some gases listed in the table not recorded on the pie chart? • Which ones are not recorded? • Which gas is the most critical to sustain human life? Gases can be identified by either their names or their symbols. Nitrogen’s symbol is N. The symbol for the Nitrogen molecule is N2, meaning that in its natural molecular state, the Nitrogen molecule consists of two N atoms. The symbol for the Oxygen molecule is O2. What is symbol for Carbon Dioxide? ______________ (Answer: CO2) Beginning Mix of Atmospheric Gases on Space Station Alpha How does the gaseous mix of Table #1 and Pie Graph #1 compare to the mix of gases in Table #2 and Pie Graph #2: Beginning Mix of Atmospheric Gases on Space Station Alpha? (Ans.: The atmosphere on Space Station Alpha begins with only the gases Nitrogen and Oxygen.) Why do you think that the beginning Space Station Alpha gases consisted mainly of Nitrogen and Oxygen? (Ans.: Because in Space Station Alpha the starting atmosphere is a man-made-mix of gases. It consists of the gases that scientists know to be absolutely necessary to keep the astronauts alive, healthy, and safe. Man needs oxygen to stay alive. The air needs Nitrogen mixed in it so that it won’t blow up with the slightest spark. Oxygen is highly explosive if it is unmixed with anything else.) If Space Station Alpha started with Nitrogen and Oxygen, why do we have to worry about the Space Station’s atmosphere? (Answer: Keep reading.) Take a deep breath – Now, don’t let it out! On Earth, we breathe in the air in Table #1 and Pie Graph #1. In the Space Station, the astronauts, on their first moment on board, breathed in the air in Table #2 and Pie Graph #2. On Earth and in the Space Station, the astronauts (and you) breathe out the air in Table #3 and Pie Graph #3. Study Table #3 and Pie Graph #3: The Gases We Breathe Out. Compare it to Tables and Pie Graphs #1 and #2. Something happens in the human body [Link] to the air that is breathed in. [Author’s.Note: Human Body Graphic and Commentary: The chemical processes within the body change the gases that are breathed. This is a complex process that starts when fresh oxygen enters the lungs. Because the oxygen is under enough pressure, the molecules bang into each and into the lining of the lungs, the alveolar membrane. Under pressure they pass through the alveolar membrane of the lungs into tiny blood vessels called capillaries. Here the Oxygen molecules attach themselves to the blood’s hemoglobin trading places with carbon dioxide molecules. The Oxygen molecules then travel throughout the body through more arteries and vessels to capillaries. From the capillaries, they pass into the fibers, tissues, and cells in our muscles, organs, and nervous system. Here, they burn when they chemically interact with the carbohydrates, fats, and proteins we get from the food we eat. This chemical burning process produces carbon dioxide. The carbon dioxide molecules enter back into the blood, switching places with freshly arriving Oxygen, and move back through the heart to the lungs. Here they pass out through the alveolar membrane and are breathed out. The burning process in the body also produces the other by-products of water vapor and gases that appear in Pie Graph #3. This burning process maintains our body’s temperature of 98.6( Fahrenheit. Just enough oxygen keeps us burning. ] By studying and comparing all three Tables and Pie Graphs, we begin to understand, not only that the body uses the air it breathes, but also that the body’s processes produce a new mix of gases. On Earth, this is not an issue. There is a lot of air. But on Space Station Alpha? The Problems with Breathing on Space Station Alpha As we can see from Table #3 and Pie Graph #3, the astronauts are polluting the air in their own Space Station. And the harder they work and exercise, the more they pollute. They are, in fact, like earth-bound factories without environmental control systems. Consider the gases coming out of our Astronauts. Carbon Dioxide and the Trace Elements and Water Vapor, all of which are being produced by the astronaut’s bodies, have to be removed from the air. If they are allowed to accumulate within the Space Station, they will pollute the atmosphere. If the Carbon Dioxide builds up, the astronauts can suffer from Carbon Dioxide poisoning [Author’s Note: Link to CO2 poisoning chart]. And that’s not all, the astronauts are producing methane, ammonia, urea, and other poisons that are very natural gases to produce, but really make a mess of the air in the Space Station. Look at what happens to the percentages of Nitrogen and Oxygen. The astronauts are using up the Oxygen. If there is not a high enough percentage of oxygen in the air, the astronauts are in danger of Hypoxia. [Ed. Note: Link to Hypoxia chart.] On Space Station Alpha, sensors attached to computers are constantly at work taking readings and making adjustments to the air’s composition. They control Space Station Alpha’s Environmental Controls and Life Support Systems. [Author’s note: Connect here to ECLSS Image Map] Maintaining a healthy atmosphere and a healthy atmospheric pressure on the Space Station is a constant challenge. There are multiple back-up and safety devices on board. If the pressures of the different gases and the total air pressure on board the Space Station are not monitored and maintained, our astronauts could be in danger without their even knowing it. Atmospheric gases are invisible and might cause dangerous situations if not kept under control and in the right proportions. |
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