This post was originally published on Smartplanet.com
Much of the waste we create ends up in a garbage vortex in the middle of the ocean. Similarly, much of the equipment we send to space eventually stops being useful and remains in Earth's orbit anywhere from several years to centuries.
This orbital debris, or space junk, can range from old satellites to flecks of paint that come off of an object when it collides with another object. The debris can be made intentionally, like when China destroyed a weather satellite with a ballistic missile in 2007. Or unintentionally, like when U.S. and Russian communication satellites collided in 2009. But no matter how it happened, the two events alone account for an estimated one-third of observable orbital debris, according to NASA.
There are more than 21,000 pieces of orbital debris larger than 10 cm, that we know of, and millions more less than 10 cm in diameter, numbers that are only growing.
But what's the problem? Won't the debris eventually just fall back to earth and burn up in the atmosphere or land harmlessly in the ocean? Potentially. The problem is that orbital debris has reached a "tipping point" where there is a space environment that is "increasingly hazardous to spacecraft and astronauts," according to Donald Kessler, retired head of NASA's Orbital Debris Program Office, in a 2011 NASA study.
More recently the U.S. government called space junk a national security threat, a notion that was dramatized in last year's Hollywood thriller "Gravity."
The nightmare scenario is known as the "Kessler syndrome" where space junk collisions become more common and create a cascade effect that eventually makes the low Earth orbit so dense with junk that space exploration would be impossible and the use of the satellites unfeasible for common missions, like communications or weather tracking, that we take for granted.
The bright side is that increased awareness of this problem has lead to numerous ideas for how to solve it. The other good news: resolution seems within reach. According to Kessler, five satellites would need to be taken out of orbit every year for the next 100 years.
Japan Aerospace Exploration Agency has teamed up with a company that makes fishing equipment to create a net that captures space debris. The idea is that a satellite will be launched that deploys a 1,000 foot wire net that can magnetically attract space junk. After about a year, the South China Morning Post reports, the net and all the junk would return to earth and burn up in the atmosphere. The main question with this idea is how do you differentiate junk from working equipment? The agency will have time to work out the kinks though. Tests of the equipment are planned for later this year but a fully functioning system isn't likely to be deployed before 2019.
The European Space Agency says it's close to testing a small, light "Gossamer Deorbiter Sail" that could be deployed when a satellite comes to the end of its life, "creating enough drag to pull a craft of up to 700 kg out of orbit to burn up in the high atmosphere," according to Forbes. A demonstration satellite could launch by the end of the year.
In a recent study, economists proposed a Pigovian tax that would discourage the excessive launch of satellites and use money from the tax of satellites that are launched to pay for the removal of space debris.
It's not just cleaning up the debris that's a problem. Big money is being invested in equipment used to protect working satellites from collisions. Lockheed Martin just won a $3.9 million contract to continue to collect data on the space objects currently in orbit.
"The cars we drive on Earth have mirrors and sensors to prevent bumps and scrapes, but if you’re trying to avoid rapidly moving debris in space, you’ll need enhanced situational awareness," said Rob Smith of Lockheed Martin.
And there are other ideas in the works:
Yet the biggest hurdles might not be coming up with innovative ideas to solve the problem. It will be getting nations to work together to implement the solutions. That's because even if a satellite from the United States is junk orbiting the earth, China, for example, would not be able to remove it. That satellite is still the property of the U.S. under international law (see page 11 of this report). Cooperation improved recently when the U.S. and Canada agreed to share space debris data. But there's still a long way to go.
As one official summarized the issue at a 2012 conference on space debris removal: "There is a paradox between the urgency of the issue and the slowness of actions. No one wants to pay for it, financially or politically."