Space Junk, the orbiting man-made space litter ranging from spent rockets to tiny remnants of collisions, has slowly been collecting since humans first launched into space.
More than 500,000 pieces of debris are currently circling low Earth orbit, traveling at speeds up to 17,500 miles per hour. If you have seen the film Gravity then you know this space debris has the potential to damage satellites, the International Space Station, and Sandra Bullock herself.
Experts have been growing increasingly concerned that this space junk could cause Kessler Sydrome, a collision that could cascade into a snowball effect of collisions. Each time a collision occurs it adds an incredible amount of space junk.
In Feb. 10, 2009, a defunct Russian satellite collided with and destroyed a functional U.S Iridium commercial satellite. The impact added more than 2,000 pieces of debris. China contributed to the problem by using a missile to destroy an old weather satellite, adding more than 3,000 pieces of debris.
The problem could get worse. There are currently thousands of satellites flying around in low-Earth orbit right now, but between now and 2025 that number is expected to increase exponentially with the popularity of Smallsats, satellites as small as shoe boxes. These Smallsats improve our GPS signals and phone calls but also create a crowded neighborhood.
Currently NASA and US Strategic Command are charged with keeping tabs on all this space junk, but with the impending SmallSat revolution, that job will become increasingly difficult.