We rely on satellites every single day for essential technology like GPS navigation. But as private companies launch massive new fleets into orbit, we have to face a harsh reality: Space up there is not unlimited.
How many satellites can we actually fit around the Earth before it becomes a problem?
To answer this, we spoke with Nicole Gugliucci, an astrophysicist from Saint Anselm College, to break down the theoretical limits of our crowded orbit.
“In the last few years, there have been a lot of companies putting up these huge fleets of satellites, making it more likely that there are going to be issues with collisions,” says Gugliucci.
NASA scientists have long warned of a theoretical tipping point known as the Kessler syndrome, which outlines a worrisome domino effect that begins when two large objects, such as active satellites or discarded rocket stages, collide at high speeds.
The violent impact shatters the machinery into thousands of tiny, fast-moving pieces of debris. This debris cloud then hurtles through orbit, inevitably colliding with other nearby satellites and shattering them in turn.
The resulting runaway chain reaction triggers a catastrophic, self-sustaining loop, ultimately creating a permanent cloud of space junk that renders the entire orbit completely unusable for future generations.
“The worst case scenario I can imagine is that there's so much debris that we literally cannot send another rocket up into space,” says Gugliucci.
This grim possibility even plays a role in the Fermi Paradox — the famous scientific question asking why we haven't found evidence of intelligent extraterrestrial life. Some scientists hypothesize that alien civilizations haven't visited us because they made the same mistake: polluting their own planet's orbit so badly that they trapped themselves at home.
Have a question about the night sky or space exploration? Send an email to the team at cosmic@npr.org.
