There is an old saying. What goes up, must come down. Seems rather fair given our experience on earth. But it also applies for what we send to space. Satellites, Space Stations, rocket boosters and everything else we’ve sent up has to be deorbited or sent out of orbit away from the earth. Otherwise, these man made space objects will:
- Orbit the earth the next few hundred million years
- Hit another satellite, space station or space craft and cause minor/massive damage
- Deorbit on its own and fall back to earth
As of this writing there is somewhere between 500,000 to 600,000 man made items still in space that we would classify as junk or debris. These items range in size from less than tip of a pen to RV sized space stations like the Tiangong-1 from China.
How often does space debris deorbit? Well it depends on how close the debris is to the earth. Debris in LEO (low earth orbit) is much more likely to deorbit over time than debris in MEO (medium earth orbit,) HEO (high earth orbit,) or GEO (geostationary.) Reason being that the closer the debris is to the earth the greater the impact the earth atmosphere will have as it disrupts the vacuum of space. The vast majority of space debris is located in in LEO and GEO which make them prime candidates to fall from the sky and maybe on to your head if you were to be so lucky/unlucky. Really depends on how you look at it. I think it would border on the lucky/cool spectrum as you would always have an interesting story to tell.
You might be thinking. So what are the odds man?? Should I wear a helmet when I go outside? When I'm home? Well, it depends on how much you like probabilities and your chances. For example:
- Odds of being audited by the IRS: 1 in 100
- Odds of winning an Oscar: 1 in 11,500
- Odds of being drafted by the NBA: 1 in 6,864,000
- Odds of being struck and killed by lighting: 1 in 174,426
- Odds of winning the Powerball jackpot: 1 in 175,223,510
- Odds of being hit by space debris: 1 in 300 trillion.
Why are the odds so low? First, roughly 70% of the world in covered in water. Second, the other 30% of the world that is covered by land in not densely populated. This helps put the odds in your favor of not being hit by space debris. Third, the majority of satellites, space stations and other space objects are designed to deorbit into the middle of the ocean. It's when something goes wrong that the odds become more likely, say 1 in 150 trillion.
Long story short. Don't stress it. You're safe and if you do get hit, message me and we'll buy a lotto ticket together.