The space surrounding Earth is getting a little too crowded, and interstellar fender-benders could have dire consequences.
On Wednesday night, two satellites came within a dangerously close distance of 47 meters from one another in the skies above Pittsburgh, avoiding a collision that could have left thousands of debris floating around in the cosmos.
LeoLabs, a satellite tracking company that helps mitigate the risk of such collisions, began monitoring the two satellites' close approach on January 27. At that point, they estimated that the two satellites would pass each other at a relative velocity of 14.7 kilometers per second at 6:39 PM Eastern — but there was a 1 in 100 chance that the spacecraft would slam into one another instead.
As time marched on, the odds of a catastrophic space jam only became worse. The next day, the company updated their calculations, increasing the collision risk to 1 in 20. You can watch a full simulation of the potential collision, here.
But despite the odds, the craft managed to pass one another by after all. Late Wednesday night, LeoLabs reassured sky watchers that they found no evidence of new debris — which means we can assume that the two satellites did not crash into one another.
The close encounter, LeoLabs says, is a potent reminder of why we here on Earth need to pay attention to what all we are throwing up into space. As the era of commercial space travel picks up pace and we increasingly rely on satellites for on-Earth communications and other technologies, these kinds of collisions could become worryingly frequent.
What satellites almost crashed?
The two satellites at the center of the panic are NASA's Infrared Astronomical Satellite (IRAS), launched in 1983, and a United States military satellite called GGSE-4, launched in 1967. Both are way past their mission timelines — essentially floating around Earth in endless space retirement.
While the satellites have been long forgotten, they represent an increasing risk of space collisions as we here on Earth keep deploying spacecraft after spacecraft into orbit. And the numbers are increasing with private space companies like SpaceX and Blue Origin also getting in on the action.
This was not the first close encounter of its kind. In September 2019, the European Space Agency had to use the thrusters on one of its satellites so it can swerve out of the way and avoid collision with SpaceX's infamous Starlink satellites. Thankfully, both satellites were operational — meaning they could be easily moved. The same is not true of space junk like IRAS and GGSE-4.
There are nearly 1 million objects larger than 1 centimeter hovering aimlessly in Earth’s orbit, according to figures from ESA.
In 2025, the agency will launch the very first space trash collector in the form of a four-armed robot that will essentially hug the debris and store it away for disposal. But five years is a long time to keep your fingers crossed something doesn't happen in the meantime.