Space Junk Facts
Since humans have ventured into space, we’ve embraced “The Big Sky Theory”. The Theory holds that space is so big, you could launch anything into orbit, and it wouldn’t collide with anything else.
In 1978 Donald Kessler (ret.), of NASA’s Orbital Debris Office, predicted that within 3 decades random collisions between manmade objects would create smaller debris that would become increasingly hazardous to spacecraft. Known as the Kessler Syndrome, a resulting chain reaction would create exponentially expanding clouds of debris. Even if we don’t launch anything else into space, an orbiting belt of debris could very well alter space exploration, as we know it.
Over the last 50 years, we’ve launched several thousand satellites into space. Yet there are only around 1,000 spacecraft that are operational at this time. Once an object stops functioning, we simply leave it in orbit.
That’s a whole lot of junk: It’s estimated that LOW EARTH ORBIT (LEO) contains 6,000 tons of space junk. GEOSYNCHRONUS ORBIT (GEO) is home to 400 dead satellites, parked in a higher graveyard orbit, where they will remain for hundreds of years.
Manmade satellites fall out of orbit and burn up in the atmosphere regularly. However, not all objects decay upon reentry. Those that survive fall to earth at very high speeds. Fortunately, 70% of the earth’s surface is water, greatly reducing the chances that a piece of space junk will fall in a populated area.
Upper stage rocket bodies weighing several tons make up a good portion of the junk in space... as do mission-‐related objects like cast-‐off bolts or o-‐rings. The rest are miscellaneous fragments: exploded rockets, left over fuel, and the list goes on.
In LEO, satellites often experience what satellite operators refer to as “close approaches” -‐-‐ two satellites passing within just a few short miles of one another. Amazingly, that can happen around 1,500 times a day.
The Father of Space Junk
Dreaming of becoming an astronomer one day, Don Kessler entered NASA’s cooperative education program to study physics. He started out studying natural meteoroids, but his attention soon shifted to debris from space launches.
Kessler wondered, “Since natural collisions occur in space what will happen with all the man-‐made material we were putting into space?” That question led him to published his landmark paper, “Collision Frequency of Artificial Satellites,” detailing the science behind what is now unofficially known as the Kessler Syndrome: Space junk collides with other space junk, producing more and more fragments, until the debris eventually renders low Earth orbit impassable.
Learn more about space debris, hypervelocity impact testing, mitigation guidelines and how to track debris:
NASA Orbital Debris Program:
European Space Agency (ESA)
White Sands Hypervelocity Impact Testing
U.S. Space Surveillance Network
IADC Space Mitigation Guidelines