What is space junk and why is it a problem? | Natural History Museum Thousands of dead satellites are currently orbiting Earth, as well as tens of thousands of fragments of space debris © ESA/ID&Sense/ONiRiXEL ( CC BY-SA 3.0 IGO opens in a new window ), cropped from original opens in a new window Space What is space junk and why is it a problem? By Jonathan O'Callaghan Since the dawn of the space age in the 1950s, we have launched thousands of rockets and sent even more satellites into orbit. Many are still there, and we face an ever-increasing risk of collision as we launch more. As long as humans have been exploring space, we've also been creating a bit of a mess. Orbiting our planet are thousands of dead satellites, along with bits of debris from all the rockets we've launched over the years. This could pose an issue one day. What is space junk? Space junk, or space debris, is any piece of machinery or debris left by humans in space. It can refer to big objects such as dead satellites that have failed or been left in orbit at the end of their mission. It can also refer to smaller things, like bits of debris or paint flecks that have fallen off a rocket. Some human-made junk has been left on the Moon , too. Rockets can release lots of little bits of debris like paint flecks when they reach space, as seen in this GoPro video. How much space junk is there? While there are about 2,000 active satellites orbiting Earth at the moment, there are also 3,000 dead ones littering space. What's more, there are around 34,000 pieces of space junk bigger than 10 centimetres in size and millions of smaller pieces that could nonetheless prove disastrous if they hit something else. The world's first satellite, Sputnik 1, was launched by the Soviet Union on 4 October 1957. Credit: NSSDC, NASA via Wikimedia Commons opens in a new window . How does space junk get into space? All space junk is the result of us launching objects from Earth, and it remains in orbit until it re-enter