Why Can’T We Breathe In Space
Space is big. Really really big. It stretches on forever across millions upon billions of galaxies all packed together like sardines. There are probably trillions upon trillions of stars, each with its own suns going around their orbits just as our solar system does around our galaxy. And then there are the black holes that devour matter — including entire stars! — when they get too close. All this matter is so far away from us we can barely sense it.
We don’t need to be able to see these objects, because gravity is a powerful force that warps light itself. That’s why you can look at the night sky and see the shapes of the constellations without any special equipment. You’re seeing how much gravity has distorted those bright points of light. Astronomers use telescopes to do this sort of thing. They build huge mirrors to reflect sunlight toward smaller mirrors (called “collectors”) where they collect light rays bent by gravitational forces. Then scientists analyze what comes back into the main mirror to figure out how fast different bodies are moving through space. These telescopes also allow astronomers to spot dark energy — the mysterious phenomenon that seems to make up more than three-quarters of the universe.
But even though we know about most of the things in space, getting our hands on some of them for testing purposes is tricky business. For example, if you were to go outside right now, you’d find yourself in an environment lacking in one key element: air. Air is invisible, but it provides life support for everything on Earth. Without it, plants would die, animals wouldn’t live long enough to reproduce and humans couldn’t survive either.
The problem is that Earth, being such a small planet, doesn’t contain much air. Most of what we call atmosphere is actually something called exosphere. The exosphere extends anywhere from tens of thousands to hundreds of thousands of miles above Earth’s surface. The exosphere starts thinning out after about 50 kilometers (31 miles) above the ground, as molecules start breaking down and becoming ionized. Above 100 kilometers (62 miles), atoms lose electrons and become neutral. Neutral atoms aren’t stable; they fall apart and break into subatomic particles. Atoms with only protons and neutrons are unstable and decay quickly. Finally, once you reach about 300 kilometers (186 miles) above Earth’s surface, atoms no longer exist. This is known as the Kármán line.
Earth’s atmosphere contains less than half of 1 percent of the total amount of oxygen available in the cosmos. So while we might think that we could bring along some extra supplies of O2 to help us breathe during spacewalks, we actually won’t need much. If we did take along a few tanks of O2, however, it would be nice to have a way to release the gas safely. One idea is to create tiny parachutes made from fibers coated in plastic film, which would float slowly down to earth from space. When they reached the ground, the parachutes would open to let the O2 loose. Another method would be to send balloons floating freely into space. Once they got high enough, the balloons could release the O2 by puncturing themselves. The downside of both methods is that the O2 released would mix with the O2 already in the exosphere, meaning that there would be no trace left behind.
So for now, astronauts will have to rely on the same type of portable O2 generator used on submarines. Known as SCRAMS, these units burn hydrogen peroxide fuel to produce O2 instead of splitting water molecules. Although SCRAMS work well underwater, they tend to run out of power and stop producing O2 fairly quickly during space missions. To prevent this problem, NASA engineers designed a new O2 generation unit called HYDROGEN PEROXIDE INJECTION SYSTEM, or HPIS. This device splits water molecules using electricity and converts the resulting hydrogen peroxide into pure O2. When the O2 reaches the astronaut, he’ll have plenty of breathable air for his next spacewalk.
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