The Science of Space Junk

March 4, 2026 • 6 min read

What is Space Junk?

Space junk, or orbital debris, refers to any man-made object in orbit around Earth which no longer serves a useful function. This includes non-functional spacecraft, abandoned launch vehicle stages, mission-related debris, and fragmentation debris. According to NASA, there are more than 27,000 pieces of orbital debris tracked by the Department of Defense’s global Space Surveillance Network.

The Kessler Syndrome

In 1978, NASA scientist Donald J. Kessler proposed a scenario where the density of objects in low Earth orbit (LEO) is high enough that collisions between objects could cause a cascade—each collision generating space debris that increases the likelihood of further collisions. This could eventually render space exploration and even the use of satellites impractical for generations.

How Do We Clean It Up?

Scientists are exploring various methods, including robotic arms, nets, and even lasers to deorbit larger pieces of junk. The goal is to push them into the atmosphere where they can burn up safely.

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