In 2016, astronaut Tim Peake of the European Space Agency shares a photo of a quarter inch in a glass window of the International Space Station (ISS). The culprit? A small sheet of space junk.
The piece of debris, perhaps a flake of paint or a metal fragment of a satellite, was only a few thousandths of a millimeter wide – not much larger than a single cell E coli.
But how can something so small cause visible damage?
“It all comes down to velocity,” said Vishnu Reddy, an astronomer at the University of Arizona. Objects at the height of the ISS and most other satellites – about 400 kilometers above Earth – revolve around our planet every 90 minutes, according to the European Space Agency. That’s more than 25,600 km / h (10,200 km / h), 10 times the speed of an average bullet shot on Earth, wrote Robert Frost, an instructor and flight controller at NASA. Quora.
Related: What would happen if you shot a gun in space?
The energy of an impact is not only related to the size of an object; velocity (velocity and direction) are equally important. Therefore, a small bullet can do so much damage; Moving at high speeds can be dangerous for any object, Reddy told WordsSideKick.
Keep in mind that velocity is additive, said Kerri Cahoy, associate professor of aerospace at the Massachusetts Institute of Technology. Thus, when two objects move towards each other as they collide, it increases the energy of their impact.
“Think of it like driving on a freeway,” Cahoy told WordsSideKick. Two fast-moving cars moving in the same direction can touch each other and just ‘barely kiss’, she said. But if a vehicle – even a lightweight, like a motorcycle – hits a car while driving in the opposite direction, it can be disastrous for both drivers.
Similarly, a fast-moving stain paint that collides with the ISS can leave a relatively large mark in space.
In space, satellites, spacecraft and debris orbit many different paths; while one object can rotate horizontally around the equator, another object can run vertically around the poles. Some objects even move ‘backwards’, which means they rotate against the earth’s orbit. As more and more debris confuses space, the Earth’s low orbit (in which the ISS rotates) changes during peak hours into a packed highway. “There could be the potential for a lot of damage,” Cahoy told WordsSideKick.
The astronauts aboard the ISS were happy that a larger piece of debris did not hit their window. A microbial-sized fragment may leave only a dent, but a pea-sized fragment can eliminate critical flight systems, according to the European Space Agency. A piece of debris as big as a table tennis ball? “It would be catastrophic,” Reddy said. At that size, space debris can cause the space station to drop rapidly, making astronauts impossible to breathe, Reddy said.
Space debris is a growing problem. The Earth’s orbit contains at least 128 million pieces of debris, 34,000 of which are larger than about 10 centimeters. according to the Natural History Museum in London – and these are just the fragments large enough to be traced. These smaller pieces form when satellites naturally weather under extreme ultraviolet radiation, when larger pieces of space debris collide or when satellites are deliberately destroyed. Larger pieces include 3,000 abandoned satellites, as well as bolts and other parts that are dumped by spacecraft during launch.
By detecting space debris, scientists can tell countries and companies when they need to steer a spacecraft out of the way of a fast-moving piece of debris, Reddy said. According to the Natural History Museum, the ISS has performed 25 of these maneuvers since 1999. And researchers are developing ways to catch debris from space, such as using hooks, nets and magnets to pull it back into Earth’s atmosphere.
Too much space debris can make it dangerous for humans to use the Earth’s orbit for satellites and other types of spacecraft. We are not close to that point yet, but it is important to prepare for the problem of space debris to prevent further congestion, Reddy said.
“We rely on space for so many things: communication, weather forecasting, banking, entertainment and military activities,” he said. “As far as our progress as a civilization is concerned, we will take many steps backwards if we do not have access to space.”
Originally published on Live Science.