The European Space Agency has just released images showing all the satellites and human-made debris now orbiting space as a result of 51 years of launching stuff since Sputnik. That's about 6,000 satellites up there—of which only 800 remain operational—plus thousands of other objects from launches and accidents. According to their mindblowing simulations things are getting a lot worse:
About 50 percent of all trackable objects are due to in-orbit explosion events (about 200) or collision events (less than 10).
Yes, we knew that there was a lot of crap out there, but not to this extent. According to the ESA, this is really bad news and urgent measures are needed. Explosions in space are not disastrous on their own, but because of the aftermath. One example: a geostationary satellite travels at 6,213 miles per hour. If it explodes, all the debris stays near the orbit, forming a cloud around the Earth within a few days, as this simulation shows:
The ESA is urging to introduce measures to mitigate this problem, like the complete depletion of fuel in rocket stages (like some Delta launchers already do following NASA's Procedural Requirements for Limiting Orbital Debris) or returning objects to Earth once their mission is complete (perhaps to destroy them on re-entry,) just like SES Americom is going to do with their brand-new AMC-14. This satellite failed to reach its projected altitude and now has to be splashed into the sea because of a dispute with Boeing, which won't let SES Americom use their patented recovery method to put the satellite into the right geostationary orbit.
The impact of these measures could be huge, as reflected by this simulation of how things could look by the year 2112, with and without taking action:
While the idea of bringing back used stages and satellites back to Earth may seem too expensive, in the long run it's clear that leaving all this trash up there is going to have huge consequences to the development of space exploration and colonisation. Those concepts may still seem science fiction for many, but as these simulations show, the current and future problem is very real, and could be extremely dangerous.
This is how it looks when orbital debris hits a spaceship, simulated in a laboratory.