How can the International Space Station orbit without burning up? – Mateo, 8 years old, New York, New York
Thousands of satellites and two operational space stations fly through Earth's orbit, including the International Space Station, which weighs as much as 77 elephants. The International Space Stationor ISS, is home to scientists and researchers from around the globe who contribute to discoveries in medicine, microbiology, earth and space science, and more.
One of my first jobs in aerospace engineering was working on the ISS, and the ISS stays considered one of my favorite aerospace systems. I now work at Georgia Tech, where I teach aerospace engineering.
The ISS orbits the Earth in a short time at 5 miles per second (8 kilometers per second), meaning it could fly from Atlanta to London in 14 minutes. But at the identical time, small pieces of rock called meteoroids shoot through space and burn up once they hit the Earth's atmosphere. How is it that some objects – corresponding to the International Space Station – orbit the Earth unscathed, while others, corresponding to asteroids, burn up?
To answer why the ISS can remain in orbit unscathed for many years, you first need to know why some things, like meteoroids, actually burn up once they enter our planet's atmosphere.
Why do meteoroids burn up within the atmosphere?
Meteoroids are small pieces of rock and metal that orbit the sun. These space rocks can travel at speeds between 7 and 25 miles per second (12 to 40 km per second). That's fast enough to cross your entire United States in about 5 minutes.
Sometimes a meteoroid's orbit overlaps with Earth's and the meteoroid enters Earth's atmosphere – where it burns up and disintegrates.
Even though you possibly can't see them, the atmosphere is filled with particles, mostly nitrogen and oxygen, that make up the air you breathe. The further you’re from the Earth's surface, the lower the density of particles within the atmosphere.
The The atmosphere consists of several layers. When something enters Earth's atmosphere from space, it must go through each of those layers before reaching the bottom.
Meteoroids burn up partially of the Earth's atmosphere called mesospherewhich is 48 to 80 kilometers above the bottom. Even though the air up there may be thin, meteoroids still encounter air particles as they fly through.
When meteoroids hurtle through the atmosphere at very high speeds, they’re destroyed by a process that causes them to heat up and break apart. The meteoroid pushes the air particles together, just like how a bulldozer pushes earth. This process creates a whole lot of pressure and warmth. The air particles hit the meteorite at hypersonic speed – much faster than the speed of sound – causing atoms to interrupt away and form cracks within the meteoroid.
The high pressure and hot air penetrate into the cracks, cause the meteorite to interrupt apart and burns because it falls through the sky. This process known as Meteoroid ablation and is what you really see while you witness a “shooting star.”
NOAA, CC BY-ND
Why doesn't the ISS burn?
So why isn't this happening with the International Space Station?
The ISS doesn’t fly within the mesosphere. Instead, the ISS flies in the next and significantly less dense layer of the atmosphere called the thermospherewhich extends from 50 miles (80 km) to 440 miles (708 km) above Earth.
The Kámán Lineconsidered the frontier of space, lies within the thermosphere, 62 miles (100 kilometers) above the Earth's surface. The space station flies even higher, about 250 miles (402 km) above the surface.
The thermosphere incorporates too few particles to transfer heat. At the peak of the space station, the atmosphere is so thin that you just would wish a box the scale of Lake Superior to gather enough particles comparable to the mass of an apple!
As a result, the ISS doesn’t experience the identical interactions with atmospheric particles, nor the high pressure and warmth that meteoroids flying closer to Earth experience, so it doesn’t burn up.
A top-class research center
Although the ISS doesn’t burn up, there are large temperature fluctuations. As it orbits the Earth, it’s exposed to alternating periods of direct sunlight and darkness. Temperatures can reach 250 degrees Fahrenheit (121 degrees Celsius) when exposed to the sun, after which they’ll drop as little as -250 degrees Fahrenheit (-156 degrees Celsius) when it’s dark – a variation of 500 degrees Fahrenheit (277 degrees C) because it moves through orbit.
The engineers who designed the station fastidiously chosen materials that might withstand these temperature fluctuations. The interior of the space station is kept at comfortable temperatures for the astronauts, just as people on Earth heat and funky our homes to remain comfortable inside.
Research on the ISS has led to progress as improved Water filtration technologiesa greater understanding of the earth Water and energy cycles, Techniques for Growing Food in Space, Insights into black holesa greater understanding of how the human body changes during prolonged space travel and latest studies on quite a lot of diseases and coverings.
NASA plans to maintain the ISS lively until 2030, when all astronauts return to Earth and the ISS will accomplish that deorbitedor be deorbited by a specially designed spacecraft.
As it sinks through Earth's atmosphere throughout the deorbiting process, it enters the mesosphere, where many parts of it heat up and decay.
Some spacecraft, corresponding to the crew capsules that carry astronauts to and from the ISS, can survive re-entry into the atmosphere Heat shield. This is a special layer fabricated from materials that may withstand very high temperatures. The ISS just isn’t designed for this and subsequently doesn’t have a heat shield.
If you need to see the space station because it flies over your area, you possibly can accomplish that Check out NASA's website to search out out when it could be visible in your area.
image credit : theconversation.com