Space junk, also known as space debris, is made up of human-made objects that orbit around Earth that serve no aerospace purpose, according to the European Space Agency. All space junk comes from over 6,000 space missions, including missions to put satellites in space. In December 2023, the agency estimated there are over 11,500 tons of space junk surrounding Earth.
Space junk travels at 17,000 mph as it orbits Earth, per Axios, and can threaten satellites and astronauts. Most space debris is tracked using ground-based radar, per the European Space Agency, by groups such as the U.S. Space Surveillance Network and the Inter-Agency Space Debris Coordination Committee.
Most space junk that reenters our atmosphere tends to burn up before reaching the ground, but in rare cases, some objects do create impact. Here’s what you should know.
Getting hit by space junk is unlikely, but not impossible
A 2023 study from the Federal Aviation Association found that, in 2021, there was a 7% chance that someone on Earth could have been seriously injured or killed from space debris.
There have been accounts of people that have almost been hit by space debris. The most recent occurrence happened on March 8 in Florida, when a battery pallet from the International Space Station crashed into a home, almost hitting the home owner’s son, The Guardian reports.
Space junk that doesn’t burn up in our atmosphere and reaches the Earth’s surface is rare, per the European Space Agency. But as more satellites and missions create more space debris, more space junk can be expected to come down to Earth.
How is space debris tracked?
According to Aerospace, the Space Surveillance Network tracks space junk that is larger than a softball. The network’s radar and optical sensors can determine orbit, reentry and crash probabilities.
On average, 200 to 400 tracked space debris objects enter Earth’s atmosphere every year, but less than 100 survive and touch the ground.
The space trash that hit a house in Florida last month was caught on the U.S. Space Command’s equipment as it entered Earth’s atmosphere, according to Ars Technica.
Its flight path went over the Gulf of Mexico toward Florida. This was noticed a few minutes before the space debris crashed into the house.
According to Aerospace, scientists can normally detect space junk reentering Earth’s atmosphere by at least a week, but it’s much more difficult to determine where the object will land or its final dive when it enters the densest part of our atmosphere.