Life on Earth is now heavily dependent on satellites. They power global communications, navigation, and countless everyday services. But as more satellites are launched into orbit, a growing number are falling back down to Earth. These re-entries are not without consequence.
What Happens During Re-Entry?
When a satellite’s mission ends, it is often brought back down to Earth’s atmosphere. These objects vaporise as they plunge through the air, breaking into their basic elements. Most of what remains is aluminium, along with smaller amounts of copper and lithium. To the naked eye, these events appear as brilliant streaks across the sky, like shooting stars.
But there’s a hidden cost. As these satellites burn, they release chemicals that affect the upper atmosphere. Scientists are now worried this could be damaging the ozone layer, the protective shield that blocks harmful ultraviolet rays from reaching the Earth.
Three Space Debris Re-Entries Every Day
The problem is only getting worse. According to the European Space Agency (ESA), at least three satellites or rocket bodies fall to Earth each day. In 2024 alone, more than 1,200 intact objects re-entered the atmosphere, not counting thousands of smaller fragments.
Jonathan McDowell, an astrophysicist and space debris expert, warned, “If SpaceX continues with their plans to expand their Starlink constellation to 30,000 satellites, then we’ll be looking at 15 reentries per day.”
New satellite constellations from companies like Amazon and national space programmes in China are expected to add even more to this count in the coming years.
Atmospheric and Safety Risks
Burning satellites mostly release aluminium oxide, a substance that can speed up ozone depletion and alter temperatures in the upper atmosphere. Professor Eloise Marais of University College London called this a worrying trend, saying it adds “more ozone-destroying pollutants… than ever before.”
These re-entries also come with a small but rising risk to people on the ground. While most satellites burn up completely, some parts can survive. In recent incidents, debris has fallen near homes in Florida, Poland, and Ukraine.
“We’re rolling the dice every time we have a reentry,” McDowell said. “Eventually we’re going to get unlucky, and someone is going to get hurt by falling space debris.”
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