If you’re the worrying type, Charles Stross has a bit more for you to fit into your nightmares:
Today, the commercial exploitation of outer space appears to be a growth area. Barely a week goes by without a satellite launch somewhere on the planet. SpaceX has a gigantic order book and a contract to ferry astronauts to the ISS, probably starting in 2018; United Launch Alliance have a similar manned space taxi under development, and there are multiple competing projects under way to fill low earth orbit with constellations of hundreds of small data relay satellites to bring internet connectivity to the entire planet. For the first time since the 1960s it’s beginning to look as if human activity beyond low earth orbit is a distinct possibility within the next decade.
But there’s a fly in the ointment.
Kessler Syndrome, or collisional cascading, is a nightmare scenario for space activity. Proposed by NASA scientist Donald Kessler in 1978, it proposes that at a certain critical density, orbiting debris shed by satellites and launch vehicles will begin to impact on and shatter other satellites, producing a cascade of more debris, so that the probability of any given satellite being hit rises, leading to a chain reaction that effectively renders access to low earth orbit unacceptably hazardous.
This isn’t just fantasy. There are an estimated 300,000 pieces of debris already in orbit; a satellite is destroyed every year by an impact event. Even a fleck of shed paint a tenth of a millimeter across carries as much kinetic energy as a rifle bullet when it’s traveling at orbital velocity, and the majority of this crud is clustered in low orbit, with a secondary belt of bits in geosychronous orbit as well. The ISS carries patch kits in case of a micro-particle impact and periodically has to expend fuel to dodge dead satellites drifting into its orbit; on occasion the US space shuttles suffered windscreen impacts that necessitated ground repairs.
If a Kessler cascade erupts in low earth orbit, launching new satellites or manned spacecraft will become very hazardous, equivalent to running across a field under beaten fire from a machine gun with an infinite ammunition supply. Sooner or later you’ll be hit. And the debris stays in orbit for a very long time, typically years to decades (centuries or millennia for the particles in higher orbits).
How about a kickstarter campaign for laser-equipped orbit-cleaning satellites? Sweep up our orbital trash before it becomes a huge problem. If you’ve read Neal Stephenson’s Seveneves, you’ve already got the image of a really extreme result of too much space junk (in the case of the novel, it was shattered pieces of the moon creating the Kessler cascade).
