Air: It's a Gas! Air On Earth air surrounds us. We tend to take it for granted. There is so much of it. We cannot see it. For a lot of people seeing is believing, but try to stop breathing! That’s one way (maybe a little too radical?) to prove that air is precious. Mission Specialists learn that air is much more than wind or smells. Air is made of gases. We feel the gas molecules. When the wind blows, moving gas molecules move our clothes, ruffle our hair, and dry the perspiration from our bodies on hot days. Because we feel them, the air’s gases must be something other than empty space. But empty space is part of what air is. [Author’s Request: Two illustrations: 1. The molecular states of solid, liquid, and gas. 2. Gas molecules: three types, a) single atom molecule (Argon, Helium, etc.), b) two-atom molecule (same element, ex. N2, O2, H2,) c) compound molecule (methane CH4). With descriptions.] In liquids and solids, there’s no space between the molecules. In liquids the molecules’ bonds allow them to flow. In solids the molecules bond tightly together and resist shifting and separation until heated to very high temperatures. In air, the gas molecules are separated by space and can be pressed tightly together. When pressed tightly enough together, gas molecules form a liquid. Scientists can both freeze and boil air’s gases that are in their liquid state. The boiling of liquid air tells air’s story. As liquid air boils, the air’s gases boil and become gas again. Each gas has a different boiling temperature. As the boiling temperature rises, a different liquid-gas boils and evaporates. In this way, scientists can identify which gases are in the air and how much of each gas is in the air. Earth: a “Big ball” in Space Our Earth’s atmosphere is made up of a mix of gases. Our bodies and minds have, over thousands of years, learned to adjust, and work, and think in this mix. For some miraculous reason, a surrounding layer of gases 130,000 feet thick formed around the Earth. This thick layer of gases presses down on the Earth’s surface and creates what we call atmospheric pressure. As we go up into the air, the air’s pressure changes because the “stack” of air’s gas molecules gets shorter the higher we go. Air pressure changes with weather, temperature, and altitude. The mix of the airs gases stays the same, unless, of course it is changed by man. The atmospheric mix of gases can change as the result of our best intentions, such as when we try to create more energy, more powerful automobiles, more factories—and even because we find breathing important. If the air changes, dangerous things might happen to us. Since it took hundreds of thousands of years to adjust to the air we have, what are the chances we can adjust quickly enough to the air we’re making? The air came first. Our bodies had to work hard to make the best of it. Even a little change could jeopardize a lot of hard, genetic work. If Earth’s air is precious, and changes dangerous, how about the air in Space Station Alpha? Space Station Alpha: A Tin Can Full of Air On Space Station Alpha the atmospheric conditions are far more precarious. Two hundred and seventy miles up in space, the minds and bodies of the astronauts keep on working just as on Earth. They require similar air-gas conditions. They need a continuous supply of nitrogen, for safety, and oxygen to keep their minds and bodies “running” smoothly—so they can think clearly and do their jobs. Changes in the atmospheric pressure or the mix of gases inside the Space Station might affect the way the astronauts work and the way they think – their ability to make life-saving decisions. What can the astronauts do if they need a little fresh air? They can’t open a window, or hatch. If they do….phooooosh…. all the air inside the Space Station will rush out into the vacuum of space. The astronauts would suffocate almost instantly—if they don’t freeze to death first. Like a submarine at the bottom of the ocean, Space Station Alpha is a “tin can” full of air completely surrounded by danger. The only difference? The astronauts cannot come up for air. They can’t come down for air, either. How do they get fresh air? Scientists, engineers, and technicians (and mission specialists) use what they know about atmospheric gases and how our bodies have adjusted to them to create a safe environment for the Astronauts. The Space Station’s technological systems create, store, clean, mix, and expel atmospheric gases. The scientists and technicians that created the Space Station’s Environmental Control and Life Support Systems (ECLSS) know air. [Ed. Note: link to ECLSS image map] The ECLSS is an ingenious web of technology supporting the life-needs of the astronauts. Because the air is technologically maintained, it has to be technologically measured at all times. Inside the Space Station, as on Earth, Astronauts are unintentionally changing the very air they breathe. As on Earth, the smallest, unintentional change in the mix of air-gases might endanger the crew. So Prepare To prepare to become a mission specialist, you must learn how changes in the air affect the human mind and body. You must “explore” air: learn about atmospheric pressure, about the different types of gases that make up the Earth’s atmosphere, and about how unwanted gases in Space Station Alpha can be dangerous to the astronauts. Your first task will be to learn about the atmosphere around the Earth, the gases it consists of. Then you can compare this information to the atmospheric conditions on Space Station Alpha.