I always begin my talks on space debris, aka space junk, with “Have you ever seen Gravity?” If you have not, you better just leave now. JUST KIDDING! However, Gravity is a great example of how astronauts can be affected by space junk as George Clooney and Sandra Bullock’s characters lose their vehicle in the first few minutes due to a collision with a debris field. But how realistic is this problem? What does space junk look like? Has this happened before?
I hate to break it to you but space junk is a huge problem. Just a couple years ago the space station had to make three maneuvers to avoid oncoming pieces of space junk and the number only seems to be growing with time. Many operating satellites face similar threats on orbit.
Space junk is mostly defunct or old satellites and upper stages of rockets. Because satellites deteriorate over time, pieces of them are also roaming about in space. This is especially true after collisions happen in orbit. So far there have been three major collisions in low Earth orbit, contributing to the more than 500,000 pieces of trackable debris. We can only track objects about a marble size or larger but there is expected to be much more pieces of smaller debris.
To help alleviate issues of space debris, governments only allow satellites with end of life operations. This can either be a way to bring the satellite back to Earth or send it far out into a “graveyard” orbit, out of the way of functioning satellites.
Personally, I have quite a lot of experience in this topic as it relates to both my undergraduate research and graduate research. My undergraduate research was on a project called DebriSat, a mock low Earth satellite which we blew up. We sent a projectile at orbital speeds to see how the materials would break up. The soda can sized projectile had to reach 7 km/s to be as fast as an on orbit collision. That is over 15,000 miles per hour or 25,000 km per hour (planes typically travel about 500 miles per hour). You can check out more about DebriSat here and eventually I will share what I am currently working on!