The International Space Station had to fire its thrusters this week to make sure it avoided space junk in orbit around Earth.
The station fired its thrusters for 5 minutes and 5 seconds in what NASA called a "Pre-Determined Debris Avoidance Maneuver" at 8:25 p.m. ET Monday to increase its distance from a piece of what used to be a Russian satellite.
NASA says the maneuver increased the ISS' altitude between 0.2 and 0.8 of a mile. Without the move, the satellite debris would have come within about 3 miles of the space station.
The fragment in question was from Russia's Cosmos 1408 satellite. Russia destroyed it with a missile in November 2021, creating 1,500 pieces of debris, according to NASA. U.S. officials condemned the anti-satellite missile test, saying it would create hundreds of thousands more pieces of debris in the coming years.
Space junk is a major problem: There are millions of pieces of debris circling Earth, most of it originating from satellite explosions and collisions. And when objects collide with each other, they can create even smaller pieces of debris.
Pieces larger than a millimeter number about 100 million, while objects between 1 cm and 10 cm in diameter number about 500,000, and 25,000 pieces of debris larger than 10 cm are known to exist, NASA says.
Space junk can threaten weather forecasting and GPS
Space junk poses a special threat to satellites, and in turn, services satellites provide such as weather forecasting and GPS.
"It is of particular risk to the United States because the United States is probably the most space-dependent power around," said Saadia Pekkanen, director of the Space Law, Data and Policy program at the University of Washington, in an interview with NPR earlier this year. "Relative to other powers, if anything happens to those satellites, it does affect the civilian, commercial and military capabilities of the United States."
Even very small pieces can be dangerous because of the speeds at which objects are traveling in orbit. Average impact speed is usually 22,000 mph, but can be as high as 33,000 mph.
Debris at altitudes within about 375 miles from the Earth's surface will usually fall back to Earth within several years. But if it's circling at 500 miles or more out, it will likely take hundreds or thousands of years for it to come down.
The International Space Station moves about once a year to get out of the way of dangerous debris. Critical parts of the station can withstand impact of objects as large as 1 cm, according to NASA. The agency didn't specify the size of the Cosmos 1408 fragment that posed a danger.
There are no international binding rules on how to manage and prevent the growth of debris in space, but the U.S., Russia, China, Japan, France and the European Space Agency have all issued guidelines. Chief among them involves designing and operating new spacecraft in a way that won't make the problem worse. There are also new technologies being tested to try to remove debris already out there.