Space debris is the collection of man-made objects around Earth, like old-satellites and pieces from collisions. They no longer serve a useful purpose.
Sizes of space debris range from microscopic particles to rocket bodies that stand several stories tall.
Collisions with space garbage have become a hazard to satellites; they cause great damage, especially to solar panels and optics like telescopes or star trackers that cannot easily be protected.
The total mass of all space objects in Earth orbit is more than 8800 tonnes.
Estimations show there are over a million pieces of orbital debris, the size of a marble or larger, trapped by gravity. There are about 22,000 spent rocket stages, dead or dying satellites, and countless fragments of human-made garbage around Earth, all traveling at speeds up to 28,000 kilometers per hour. That’s about 7 times faster than a bullet.
So, imagine the damage that a rocket fragment crashing into a satellite can cause. At such speeds, even tiny particles can wreak havoc.
Most of the debris, however, does not survive the severe heating which occurs when re-entering the Earth’s atmosphere.
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But about 20–40% of the mass of larger-size spacecraft or rocket bodies, or parts made of particularly high-melting steel or titanium alloys, may survive the re-entry.
Pieces which do survive are most likely to fall into the oceans, other bodies of water, or onto sparsely populated regions like the Canadian Tundra, the Australian Outback, or Siberia in the Russian Federation.
During the past 50 years, an average of one object has re-entered Earth’s atmosphere every day. No serious injury or significant property damage caused by the debris has been confirmed yet.
The European Space Agency considers it as “catastrophic” if an object larger than 10 cm collides at a speed of about 10 km/s in low-orbit. Catastrophic in space is something like the destruction of a spacecraft.
What’s worse is that collisions create something called the Kessler Syndrome where it becomes a cascading effect: debris creates more debris and on and on it goes.
But how does the International Space Station protect itself against space debris?
The space station has orbital debris shields in place to protect from debris less than 1.5 centimeters in size.
Ground control tracks larger debris. If needed, the space station can use its thrusters to safely move away from the debris.