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Mesmerizing graph shows uncomfortably close encounters between space junk

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A new online tool illustrates how crowded space has become

Image: The Verge/Alex Castro

As the number of satellites and space junk in orbit continues to increase, so do the chances of these human-made objects colliding with one another, potentially creating more debris that could threaten other healthy spacecraft. Now, a new tool shows just how crowded Earth orbit is by tracking space objects through their close calls every couple of seconds.

Called the “Conjunction Streaming Service Demo,” the graph tool illustrates in real time the sheer number of space objects — out of an assortment of 1,500 items in low Earth orbit — that get uncomfortably close to one another in a period of 20 minutes. While the X-axis keeps track of the time, the Y-axis shows the short distance between two approaching space objects, ranging from five kilometers to the dreaded zero kilometers. On the graph is a series of arcs demonstrating when two pieces of debris rapidly move toward one another, make their closest approach, and then speed away.

No matter when you glance at the tool, there is always an abundance of arcs on the graph. If the arc is extremely stretched, then two objects just had an extra close call. And some get frighteningly close within just a few minutes. In the time I wrote this story, the closest that two objects got to one another was a mere 60 meters. Each arc is color-coded, too, indicating which types of objects are approaching one another. Green arcs indicate two operational satellites that could potentially move out of each other’s way; yellow arcs indicate one movable satellite and one non-maneuverable object; red arcs indicate two dead objects, which have no choice but to continue on their potential crash course. There are a lot of red arcs on my graph.

The visualization is the creation of Moriba Jah, an associate professor at the University of Texas who specializes in tracking orbital debris. He said the goal of the tool is to show that objects skirt by each other all the time, despite the vastness of space around Earth. “Things are crisscrossing each other at very high speeds,” Jah tells The Verge, noting that some of these objects are moving 15 times the speed of a bullet. “These things are traveling really, really fast and definitely coming close to each other. People need to be aware of that.”

Jah’s visualization draws on orbital data collected by the United States Air Force, which is responsible for keeping an extensive catalog of the space objects circulating around Earth. He noted that the graph is just showing predictions based on that data, and the objects’ positions could be slightly off. It’s also important to remember that while these things are getting close, most of these satellites are relatively small. “This is why actual collisions aren’t frequent,” says Jah. “Even though things are coming within [a couple hundred] meters, the actual size of the objects is much, much smaller.”

To avoid potential collisions in space, the Air Force will warn satellite operators if their spacecraft might run into something and will issue notices when the odds are high of a collision. If it’s possible, operators will then move their satellites out of the way to avoid a potential impact. It’s a process that happens all the time, usually without much fanfare. And right now, satellite collisions in space are exceedingly rare. The most notable crash in orbit occurred in 2009 when an Iridium communications satellite collided with a dead Russian satellite.

But that one collision illustrated what’s at stake when satellites get close. The mishap created thousands of pieces of debris in orbit, which then posed their own threats to other functioning spacecraft.

Experts worry that this kind of incident might become more common in the future. Currently, there are about 2,000 operational satellites in orbit and more than 22,000 pieces of debris being actively tracked by the US Air Force. The number of satellites in low Earth orbit is set to increase substantially, though, especially as private companies like SpaceX, OneWeb, and Amazon vow to fill Earth orbit with thousands of spacecraft to beam internet coverage to the planet below. Already, one of SpaceX’s satellites got too close to a satellite operated by the European Space Agency, which prompted European officials to move their vehicle out of the way.

A study by NASA estimated that practically all of the satellites in these mega-constellations will have to be safely taken out of orbit every five years, or the risk of collisions will increase exponentially. With Jah’s tool, it’s clear that even now low Earth orbit is packed, which means managing all of the incoming space traffic will be key if we want to keep space clean.

“It’s not to be interpreted as ‘Wow, look at all these collisions.’ No,” says Jah. “But look at how close these things are getting. And that traffic is just going to increase. So the bottom line is that there is definitely an increased risk of collision with that increased traffic coming close to each other.”