Massachusetts, Gatra.com- In 2016, European Space Agency astronaut Tim Peake shared a photo of a quarter-inch dent gouging out the windows of the International Space Station (ISS). The culprit? A small piece of space junk. Live Science, 14/03. Pieces of debris, perhaps paint splinters or metal shards from satellites, are only one-thousandth of a millimeter in size – no bigger than a single bacterial cell E. coli. But how could something so small cause any visible damage? “Everything depends on speed,” said Wisnu Reddy, an astronomer at the University of Arizona. Objects at the height of the ISS and most of the other satellites – about 250 miles (400 kilometers) above Earth – rotate around our planet once every 90 minutes, according to the European Space Agency. Its speed is more than 15,600 miles per hour (25,200 km / h), 10 times the average rate of a bullet on Earth, Robert Frost, an instructor and flight supervisor at NASA, writes in Quora. The energy of an impact is not only related to the size of an object; velocity (velocity and direction) is equally important. That’s why small bullets can do so much damage. When moving at a sufficiently high speed, any object can be dangerous, Reddy told Live Science. Remember that speed is additive, said Kerri Cahoy, a professor of aeronautics and astronautics at the Massachusetts Institute of Technology. So, if two objects move in opposite directions when they collide, it increases their collision energy. “Think of it like driving on the highway,” Cahoy told Live Science. Two fast-moving cars moving in the same direction can touch and “barely smell each other,” he said. But if a vehicle – even a light one, such as a motorcycle – hits a car while traveling in the opposite direction, it could be disastrous for both drivers, he said. Likewise, in space, fast-moving paint stains that collide with the ISS can leave relatively large marks. In outer space, satellites, spacecraft and debris orbit in many different paths. One object may orbit horizontally around the equator, another object may rotate vertically around the poles. Some objects even move “backwards”, meaning they rotate in the opposite direction to Earth’s orbit. As more and more debris clutters space, the low Earth orbit (where the ISS rotates) turns into a busy highway like during rush hour. “There is the potential for a lot of damage,” Cahoy told Live Science. The astronauts on the ISS were lucky that even bigger debris didn’t hit their windows. The microbial-sized fragments may have left only a dent, but pea-sized fragments could deactivate critical flight systems, according to the European Space Agency. A piece of debris the size of a ping-pong ball? “That would be catastrophic,” said Reddy. At that size, space junk could cause the space station to drop its pressure rapidly, making it impossible for astronauts to breathe inside the plane, Reddy said. Space debris is a growing problem. Earth’s orbit contains at least 128 million pieces of debris, and 34,000 of them are larger than about 4 inches (10 centimeters), according to the Natural History Museum in London – and that’s just a fraction large enough to detect. These tiny pieces are formed when satellites naturally experience conditions under extreme ultraviolet radiation, when larger chunks of space debris collide or when satellites are accidentally destroyed. The larger portion includes 3,000 stranded satellites, as well as bolts and other parts released by the spacecraft during launch. By tracking space debris, scientists can tell countries and companies when to move spacecraft off the track of fast-moving debris, Reddy said. The ISS has performed 25 of these maneuvers since 1999, according to the Natural History Museum. And researchers are developing ways to get trash out of space, such as using hooks, nets and magnets to pull it back into Earth’s atmosphere. Too much space junk could endanger humans to use Earth’s orbit for satellites and other types of spacecraft. It’s important to tackle the space debris problem to prevent further accumulation, said Reddy. “We rely on space for many things: communications, weather forecasts, banking, entertainment and the military,” he said. “In terms of our progress as a civilization, we would take a lot of steps back if we didn’t have access to outer space.”
Editor: Rohmat Haryadi
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