Illustration of space debris orbiting the earth
Alamy Stock Photo
Two old spaceships may be on a collision course about 1,000 kilometers above the earth's surface. If they hit each other, smashing them could create a spray of dirt that would be extremely dangerous to other satellites and could set off a chain reaction of collisions.
The two objects at risk are a Soviet Parus navigation satellite, launched in 1989, and a Chinese rocket booster, launched in 2009. Both have no propulsion method on board so there is no way to steer them away from each other.
"This is less common these days, and usually you have a drive on the satellite so at the end of the mission you lower your orbit so far that it re-enters and falls into the sea or burns," says Jonathan McDowell at the Harvard-Smithsonian Center for Astrophysics. But there are many of these older objects in orbit that cannot prevent them from hitting one another.
According to LeoLabs, a company that tracks down space debris, the two objects will pass within 12 meters of each other on October 16, and the probability of a collision is over 10 percent. A collision would reduce both spaceships to splinter clouds that hurtle through orbit and potentially hit other satellites.
"When you have a collision, the debris ends up in these elliptical orbits where they cross many elevation tracks," says McDowell. "It's a little worrying when you have something like this – it just doesn't just stay safely on its trail."
Part of the fear is that such a cloud of debris could trigger a scenario known as Kessler Syndrome, in which the debris keeps hitting other satellites, causing more debris in a kind of domino effect of destruction.
Such narrow passes occur once or twice a year, with actual collisions occurring only about once a decade, according to McDowell estimates. However, as we launch more and more satellites, they could become more common. "If we don't act, this problem will only get worse," he says.
If we don't stop putting piles of space debris into orbit and start cleaning up our old clutter, satellite collisions could be the order of the day.
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