What will happen to the space debris in orbit?

Space is having a moment.  The recent activity, although exciting, raises some concerns. The amount of space debris is growing, despite requirements for satellite deorbit and disposal, and the problem will soon escalate. About 11,000 satellites have been launched in the 64 years since Sputnik 1 in 1957

Now we’re at the point where about 70,000 satellites could enter orbit if proposed plans come to fruition—an explosion of interest based on potential new markets, innovative architectures, and more sophisticated technologies. Even if all the proposed constellations fail to deploy, many more satellites will be in space. Unless actively deorbited, they will remain there for months to hundreds of years, depending on the altitude.

Exactly what is space debris? Many people think this phrase refers to a gigantic hunk of metal about to crash into a major city, but only some of the millions of objects in orbit are as large as old upper-stage rockets and space stations. Much of the rest consists of tiny particles, such as paint flecks. The US Space Surveillance Network was tracking about 20,000 pieces of debris in orbit in 2019. Today, there are about 27,000 pieces of debris, most of which are over ten centimeters in diameter. The trajectories of the rest—and what they might hit and when—are uncertain.

Given the speed at which orbital objects move, even a collision between small debris and another object on a crossing trajectory can be catastrophic. The International Space Station (ISS), which is designed to survive impacts by debris up to one centimeter in diameter, was damaged in May 2021 when an object about five millimeters in size punched a hole in the thermal covering of its robotic arm. The ISS, which has had to maneuver repeatedly to avoid larger debris, didn’t suffer functional damage, but the incident reminded us that even major space systems are vulnerable to hits from tiny objects.

Don’t be surprised if reports of collisions increase over the next few years. There is only about one tracked object for every 18 million cubic kilometers in low-Earth orbit, but this number doesn’t include potentially lethal smaller debris, nor does it account for the relatively greater density of objects in certain orbits and the distance each object moves over any given time. Both of those factors increase the chances of collision, even in a largely empty environment. Space debris cannot be controlled and may be in the skies for centuries, depending on the orbits and collision dynamics, so the problem will remain.

Experts have been discussing the space junk problem since the 1960s, leading NASA’s Donald Kessler to author a groundbreaking 1978 report on the chain of reactions that could occur once debris reached a certain level—an effect now referred to as the Kessler syndrome. A few high-profile collisions have also focused attention on the problem. In 2007, China tested an antisatellite (ASAT) weapon by intercepting a non-operational weather satellite (a FY-1C polar-orbit satellite of the Fengyun series). The resulting explosion created a cloud of space debris with more than 3,000 objects—the largest ever tracked. Similarly, a 2009 collision between the defunct Russian satellite Kosmos 2251 and an Iridium commercial communications satellite produced more than 2,000 pieces of debris.

McKinsey