While awareness about potential environmental disasters here on earth is gaining ground, most people are unaware of the growing danger looming just overhead – that is, until some of it crashes back to earth.
Just last week, a large piece of space debris fell several hundred kilometers and landed in Kachin, northern Myanmar. Residents reported hearing a loud noise that was mistaken for an explosion or possibly artillery. The noise turned out to be made by a five-meter (fifteen foot) long tank and another smaller piece of debris that may have been from a recently launched Chinese rocket.
Even though this particular piece of junk had a safe, if dramatic, end, there is a real threat posed by the estimated 100,000,000 pieces of junk still floating around up there. Only a small percentage of these pieces are larger than 3.5 inches (10 cm) in width, but when accelerated up to 28,000 kilometers per hour (17,400 mph), even a discarded nut or bolt can be deadly.
Dr Hugh Lewis recently warned at the Royal Astronomical Society in London that this junk poses one of the greatest environmental problems for humanity.
The biggest problem with space junk is that once it is in orbit, it can be extremely difficult to clean up. The small size and high velocity of these wily streakers make them nearly impossible to catch and remove. They just keep orbiting until their orbit degrades, which can take millions of years, or until they hit something, like the fleck of paint that chipped the window of the International Space Station. If it had been anything larger, it could have cause more significant damage or even destroyed the station.
One of the first scientist to raise the alarm on space junk was Donald Kessler in 1979. He warned that adding too much junk to Earth’s orbit could render it impassable for generations if a collision cascade occurred. This is when two larger objects crash into each other creating thousands or millions of small pieces, each of which is large enough and going fast enough to destroy anything they encounter. When they do so, they make millions more pieces, and so on, and so on. Eventually this chain reaction of collisions would fill the entire orbit with pebble-sized objects that destroy anything in their path.
This kind of a catastrophic collision cascade would render Earth’s orbit completely impassable for generations until it is cleaned up. This task would take orders of magnitude more effort – like trying to kill a mosquito swarm with a pin.
“It’s not just that satellites can be damaged or destroyed by space debris today or tomorrow, it’s that the actions of our generation may affect the dreams and ambitions of future generations to work and live in space, ” says Dr Lewis. “Tackling the problem of space debris is one of humankind’s greatest environmental challenges, but it is also perhaps the one that is the least known.”
Dr Lewis says cleaning up orbital space may already take years. The largest piece of space debris is currently Envisat, an Earth observation satellite the size of a double-decker bus. But, the real threat comes from the swarms of debris that are left after collisions that have already occurred – such as the the swarm of 2,000 pieces of debris that was left by a collision between a defunct Russian satellite, Cosmo, and a US commercial satellite in 2009.
The good news is that several startups have started taking the problem seriously. Ideas include shooting debris with lasers, to using grappling satellites that push non-functioning satellites back to earth and use the momentum boost to jump to their next target.
As an active participant in space exploration and technology, Noosphere Ventures has a special interest is building sustainable, international space policies. They already have space related projects such as EOS, EOSDA, Aquila Space and space junk is their one more area of interest. Their plan to build a constellation of near-Earth imagining satellites relies heavily on keeping these orbits clean for generations to come.
By working on a variety of directions at once, researchers and engineers are inching closer to reaching the goal of a sustainable space program. The hope is that through a combination of policy and investment, we can avoid the potential disaster that could be hovering directly overhead.