Earth’s atmosphere is getting cluttered with man-made space junk

Space junk isn’t just a growing danger for astronauts in space, it could also impact life down on earth

Today's expression: Close call
Explore more: Lesson #303
October 15, 2020:

Did you know there are hundreds of thousands of man-made objects circling our planet? The objects are also multiplying: they collide into each other and split into smaller pieces. Scientists around the world are trying to figure out how to harness the objects from space and bring them back down to earth, but there isn’t a proven method yet. Plus, learn what a “close call” is.

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The gathering danger of junk in space

Lesson summary

Hi there, welcome to Plain English lesson 303. I’m Jeff; JR is the producer; and you can find this full lesson at PlainEnglish.com/303. The full lesson, of course, includes the English transcript, translations, the video lesson, and more. PlainEnglish.com/303.

Coming up today: The most famous thing in Earth’s orbit is the moon. The next-most-famous thing is the International Space Station. But did you know that there are hundreds of thousands of man-made objects circling our planet? And did you know that the vast majority of that is junk—hurtling through space, waiting to crash into satellites, rockets, and even the Space Station? Even more alarming, there’s no proven way to get rid of space junk once it’s in Earth’s orbit. The expression we’ll talk about today is “close call.” And JR has a song of the week.

By the way, here’s a quick definition before we start. “Junk” is an informal word meaning, “discarded objects.” The drawer in my office at work is full of junk. I’m dreading the day I go back and have to clean it out. Your garage might be full of junk. Just old toys, spare parts from a lawn mower, chargers for devices that stopped working in 2007, a flat tire: all these things are junk you might find in a garage. So that’s the word “junk,” and now you’re ready for Lesson 303.

Search for a solution to space junk

What goes up must come down: the maxim is true everywhere on earth. It is not true, however, in outer space. And that’s a problem for satellites, space shuttles, space stations, astronauts, and really anything that goes up into space.

Anything launched a few hundred miles above the earth will eventually be pulled down toward the earth’s surface. Most objects burn up or disintegrate as they pass through the atmosphere. But get high enough into earth’s orbit and objects won’t fall down: they’ll spin indefinitely around our planet.

These objects include active satellites, former satellites, spare parts, bodies of old rockets, and other debris—together, anything not active or functional is called “space junk.” The US military closely monitors a catalog of tens of thousands of space junk objects that are at least ten centimeters in diameter. Ten centimeters is about three times the size of a tennis ball, for perspective. Those are the biggest objects that can cause the most damage if they collide with something.

There are between 500,000 and one million objects between one and ten centimeters in diameter circling the earth at high speeds—in other words, the size of a marble and larger. These are small, but still dangerous. Go a little smaller and some estimates say that there are up to 100 million objects that are a millimeter or more in diameter. These are the very, very small objects. But they are circling the earth at a terrifying speed: about 17,000 miles per hour. Even a small object moving at a high speed can cause a lot of damage.

Consider this: if a single one-centimeter-long bolt crashed into something in space, it would have the same explosive force as a hand grenade would on earth. That could bring down a large commercial or military satellite. A single fleck of paint, hurtling through space, can damage the exterior of a space shuttle or the space station.

This is more than a theoretical discussion. In September, a single small piece of space debris recently came close to crashing into the International Space Station. It might have destroyed the entire International Space Station. To prepare, astronauts on board took shelter in the Soyuz capsule that could take them back to earth in case of an emergency. In the end, the object passed within eight-tenths of a mile of the Space Station. Eight-tenths of a mile is nothing in space: a catastrophe was narrowly averted.

This was not the first close call at the International Space Station, nor will it be the last. The US military tracks tens of thousands of large objects circling the earth. When one looks like it might collide with the Space Station, the Space Station moves safely out of its way. But they need a minimum of five-and-a-half hours’ notice to do so; sometimes the objects sneak up on them and sometimes they can’t move the station fast enough. In those cases, astronauts need to prepare to evacuate in case the worst happens.

It’s not just astronauts that are in danger. In 2009, two satellites crashed in orbit: an active American one and a defunct Russian one. The American owner lost its satellite, but that’s not the end of the story. When two things collide in space, they break apart. Those two satellites crashed into each other at high speeds and the broke apart, adding thousands of smaller, but still dangerous, objects into orbit.

Space scientists are worried about something called the “Kessler effect,” named after the NASA scientist that first described it. Objects in space, if they’re up high enough, don’t fall down to earth; in space, they don’t disintegrate. That means they might stay up there for thousands of years, if not longer, spinning around, waiting to crash into one another. If the the earth is circled by large and small objects, they will eventually collide. When they collide, they break up; as they break up into smaller, more numerous pieces, collisions will happen more often.

The dystopian outcome seems inevitable: more and more collisions will create a thick cloud of tiny space objects, eventually making it impossible to use this portion of the earth’s orbit. That could imperil communications, weather forecasting, navigation, and military uses of satellites. It could seriously hamper our ability to launch scientific missions that need to pass through low earth orbit to gather information about the universe.

As ever, it is easier to pollute than it is to clean up. The first step is to stop making the problem worse. Space agencies and governments are starting to follow voluntary guidelines that say that defunct equipment should be returned to earth and collisions of large objects should be actively avoided.

There is also a technical race for a way to remove the largest abandoned objects from space. A team in England is testing a contraption that would capture a large space object in a net and pull it down to earth; a team in Japan is experimenting with using large magnets to attract objects in space. The European Space Agency is planning to launch a robot that would capture a defunct rocket and bring it back to earth.

Similarities to ‘Gravity’ movie

If you saw the movie “Gravity,” this might sound familiar. In the movie, there’s a military conflict that sets off the “Kessler effect” where a cloud of debris is so dense that it doesn’t allow astronauts to get back to earth. Scientists say this isn’t an accurate depiction—not that it can’t happen, just that it can’t happen so fast. Like so many things, this is a gathering danger that happens over the long run, instead of all at once.

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Expression: Close call