Illustration of space debris orbiting the earth
Alamy Stock Photo
About 1,000 kilometers above the surface of the earth, two old spaceships narrowly avoided a collision. If they had met, the destruction could have created a spray of debris that would have been extremely dangerous to other satellites and could have sparked a chain reaction of collisions.
The two objects are a Soviet Parus navigation satellite that was launched in 1989 and a Chinese rocket amplifier that was 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.
LeoLabs, a space debris tracking company, predicted the two objects would pass within 12 meters of each other on Oct. 16, increasing the likelihood of a collision to over 10 percent. Fortunately, this seems to have been avoided, the company says.
Such a collision would have reduced both spaceships to splinter clouds that sped through orbit and possibly 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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