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  • This video is made possible by Brilliant, learn about astronomy, gravitational physics, and more by visiting using the link in the description.


  • When you think of space, you usually think of an endless place with unbelievable distances between stars.


  • Though, the fact of the matter is that the vast majority of human activity in space for far has taken place in a narrow slice just 2,000 kilometers above the Earth's surface.


  • Known as Low-Earth-Orbit, or LEO for short.


  • This area contains the International Space Station and over 2,000 government and commercial satellites that provide everything from television signals, GPS, weather forecast, and much more.


  • However, in addition to all of these incredible technological achievements, humanity has also created a very large problem that cannot only, completely undo all of this progress, but also prevent us from visiting space again for several generations.


  • In addition to space stations and satellites, LEO is home to tremendous amounts of garbage and debris we've been throwing out ever since we first started visiting space.


  • Most of this junk consists of tiny objects like dust from solid rocket motors, flakes of paint eroded off of vehicle surfaces, or leaked frozen coolant from nuclear satellites.


  • Whatever the source, it is estimated that there are over 100 million tiny pieces of junk less than one centimeter wide currently zipping around the Earth at speeds of 22,000 kilometers per hour(13,670 miles per hour) or faster


  • If that doesn't sound like much, this image here is the aftermath of one of these flecks of paint that struck the front window of the Space Shuttle Challenger in 1983


  • In addition to the small stuff in LEO however, there are also an estimated 500 thousand pieces of junk between 1 centimeter and 10 centimeters wide.


  • All of this stuff mindlessly orbiting around the Earth will eventually result in collisions between them at extremely high velocities.


  • Which creates a large number of new fragments, these fragments will then go on to eventually collide with other objects, which creates even more fragments, which will inevitably collide even more objects and SO ON AND SO ON.


  • Until we enter the Kessler Syndrome, a hypothetical future scenario first proposed by Donald J. Kessler back in 1978.

    直到我們進入 "凱斯勒綜合症",這是唐納德-J-凱斯勒在1978年首次提出的一種假設性的未來情景。

  • Since it can take years, decades, or even centuries for space junk to enter into Earth's atmosphere and burn up on its own.


  • When we lose something in space it generally sticks around for a pretty long time.


  • These random collisions between fragments in space could eventually result in so many tiny fragments traveling at insanely high speeds,


  • The Low-Earth-Orbit would effectively be like a constant shooting range.


  • In the worst case scenario, all currently existing satellites in LEO would be destroyed into millions of tiny pieces.


  • Launching any new mission into space from Earth's surface would be destroyed almost immediately by these pieces.


  • Rendering any space mission in the future a suicide mission


  • We would lose all the technology that satellites provide to us and several generations would be robbed of the promise of space travel while we wait patiently for the garbage to get rid of itself naturally.


  • So, is the Kessler Syndrome inevitable?


  • Back in 2009, a defunct Russian military satellite collided with an operational US commercial satellite, which shattered both into thousands of different tiny fragments


  • This is the most significant unintentional collision has so far happened, but an intentional collision in 2007 created even more fragments. (Andrew N: I'm done here.)


  • In that year the chinese government tested an anti satellite missile by using one to destroy one of their own satellite in LEO


  • This event produced over 2,000 golf ball sized or larger fragments as well as over 150,000 tiny debris particles


  • In 2011, some of the debris from this test passed a mere 6 kilometers away from the international space station


  • One of the most dangerous potential triggers of a Kessler syndrome in LEO is the now defunct ENVISAT satellite launched by the European Space Agency in 2002


  • Contact was lost with the satellite in 2012 and now the 8000 kilogram piece of junk gets passed within 200 meters by two other catalog pieces of space junk every year


  • Since ENVISAT will likely remain in orbit around Earth for the next 150 years and the rate of collision is expected to increase


  • it could easily become a source of space junk some time in our future


  • The Kessler syndrome is not inevitable though and can be avoided if we try to avoid it


  • we need to think of space the same way we should think of our oceans and land


  • A valuable ressource that is in an entire need of protection


  • The only way to remove garbage from space is to go up and remove it ourselves


  • or wait for a very long time for it to go away naturally


  • Abandoning space is never an option


  • NASA already concluded in 2005 that even if no further launches of objects into space were made, collisions


  • between already existing satellites would create fragments faster than atmospheric drag would remove fragments


  • The situation is an incredibly serious one with humanity's future literally on the line


  • We have to explore ways to improve this situation in the future, and we must carry on in the present and hope for the best


  • If you want to one day work in space and help the humanity avoid the Kessler syndrom, you'll need a better


  • understanding of how gravitational fields and orbits work, and there's no better place


  • to gain an understanding of scientific concepts than


  • As of their learning in their gravitational physics course, earth's gravitational field looks more like this


  • and if you drop a bowling ball right here, it will be tavelling 1389 meters per second when it crashes into the surface

    如果你把一個保齡球扔在這裡 當它撞上地面時,它將以每秒1389米的速度前進

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  • like the Hohmann transfer with their straight forward explanation


  • simple graphics and thought provocing puzzles which help you think like a scientist


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This video is made possible by Brilliant, learn about astronomy, gravitational physics, and more by visiting using the link in the description.



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為什麼我們未來可能無法訪問太空? (Why We May Not Be Able to Visit Space in the Future)

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    林宜悉 發佈於 2021 年 01 月 03 日