For millennia, mankind has used Earth’s resources however it wanted, and when we were done with something, we simply abandoned it. Most of this stuff will - eventually - return to its component parts, thanks to weather and other natural events.
But there is no weather in space, so what happens to stuff that gets abandoned there?
Mostly, it stays where we left it, usually in some kind of orbit around Earth. Lose contact with an old satellite? That’s okay, we need a new one anyway; we’ll just put the new one in a new orbit. Somebody lost their wrench while working outside? I think the job can still be done with this other wrench and a little ingenuity. The lost wrench? Oh, just move the station another kilometer higher, and you should be fine.
Yes, we’ve been cavalier about the junk we’ve left out there. Some gets sent into a ‘graveyard orbit’ at the end of its usefulness. Other stuff eventually is pulled toward the Earth and (hopefully) burns up before it hits the ground. Remember Skylab? That was scary, to know this big thing was coming down, that it would not burn up completely, but not know exactly where it would hit. Then it broke into pieces, some of which still made it to the surface, and even more uncertainty where they would hit.
Some satellites had a nuclear reactor to power their equipment. At the end of their ‘life’, many were sent to a graveyard orbit, but others fell to Earth, where they became a problem. Even those in the graveyard could be punctured by a micro-meteor and leak coolant from the reactor. The coolant would solidify and become droplets of more junk.
So, let’s see, we have dead satellites, booster stages, fragments of booster stages that have exploded, fragments caused by collisions, and lost equipment, just to name a few categories of space pollution. Now, the movies always depict (these days) a tool as having a tether to connect it to the astronaut, but it apparently took time to think of doing that. The ‘lost equipment’ category includes: a glove, 2 cameras, a thermal blanket, bags of garbage, a wrench and a toothbrush. Okay, those bulky space suit gloves can make it difficult to maintain a grip, but how does an astronaut lose one of his gloves?
People try to keep track of all this stuff, try to avoid collisions with equipment still in use. I don’t know who supplied these numbers, but there are over 170,000,000 pieces of debris smaller than 1 cm, as of July 2013. Additionally, there are 670,000 pieces between 1 and 10 cm (3.9 inches), and 29,000 pieces larger than 10 cm.
So, who cares? Most of it’s tiny, and if it’s big enough to do damage, you just move your ship or satellite out of the way. Yes, most of it is tiny, but at the speeds they travel, even the tiny ones pack quite a punch. And the equipment can’t always move out of the way.
The Kessler syndrome theorizes that once space debris reaches a particular density, there will be a chain reaction of collisions, each breaking its components into smaller pieces, which go on to have more collisions... It’s uncertain whether the Earth has already reached that point, but it’s not something we want to happen. The Earth could become completely swaddled in debris to the point that we could no longer launch ourselves into space. There goes our glorious dreams of a Space Empire! Or even of just getting off this rock to colonize... any place else.
Would such a debris cloud cut the amount of sunlight that reaches us? That might help mitigate global warming! If not, then I guess we’ll just bake ourselves on the ground as we kick ourselves for making it impossible to move away.
There have been many suggestions on how to remove space debris. At least one country has built their idea and sent it up for testing, but couldn’t get it to work. Most don’t see it as ‘cost effective’.
So, here’s my idea. If you have a big problem, you need to think big. Build a space station. I know, we have one, but that’s not big enough. We need a big one, with manufacturing capabilities and housing/entertainment for the workers. Use a small space tug to go out, grab debris and bring it back as ‘raw material’ for building interplanetary space ships.
Or maybe you prefer to sit back and wait for ‘nature to take its course’?
By the way, have you seen the movie Gravity? That was the Kessler syndrome in action.