Since the Russians put Sputnik in orbit in 1957, a heavy amount of space junk, from old satellites to nuts and bolts, has clogged up the orbit around Earth; as of February 2011, there were 10 million pieces of man-made debris in space, according to the Sydney Morning Herald. This puts us in real danger of something scientists call the Kessler Syndrome: Low Earth orbit becomes so crowded with artifical satellites and other trash that collisions occur, generating more pieces of debris that will in turn cause more collisions, creating a domino effect that could hinder space exploration.
Larger pieces of space junk can be tracked and sometimes avoided—the International Space Station (ISS) can change orbit to get around debris—but even smaller pieces, which are eventually pulled into Earth's atmosphere and burn up, are dangerous when moving at these speeds in space. According to Popular Mechanics, a paint chip moving at hypervelocity is capable of punching a 0.025 centimeter hole in a U.S. satellite.
Scientists are seeing evidence of the Kessler Syndrome—orbital debris is on track to triple by 2030—and are on the hunt for solutions to our space junk problem. Various nations have put forward clean-up plans that range from practical to Star Trek levels of ambition. Here are five ideas.
The Defense Advanced Research Projects Agency (DARPA), an agency of the U.S. Defense Department that develops and funds technology used by the military, plans to refurbish and recycle lifeless satellites that are floating around in space—with robots.
DARPA’s Phoenix program hopes to scavenge the space debris by using robots that tag along on commercial satellite launches and attach themselves to defunct satellites. From there, the robots will collect parts, particularly antennas, which can be re-used to craft a communications network for the military at low cost.
Here’s how they’re hoping it will work: Nanosatellites, known as a satlets, will be carried in PODS (Payload Orbital Delivery System) that will piggyback into space on a larger commercial satellite being sent into orbit. Once in space, the PODS would rendezvous with another type of salvaging spacecraft (NASA calls this a “tender”) launched into orbit, that will then navigate it to the dead satellite. The tender and PODS stay together from then on. This is when the robot will go to work, using robotic arms to remove an antenna and installing the satlets into the antenna. This creates the new communications network.
The agency is planning the first Phoenix mission for 2015 and is targeting 140 dead satellites for repurposing.
2. Kamikaze Space Janitors
CleanSpaceOne—a proposed satellite from scientists in Switzerland—will go into space as a single-capture mission, grabbing debris and heading back to Earth’s atmosphere, where both the CleanSpaceOne and its collection will burn up on re-entry. Switzerland will build many of the CleanSpaceOne satellites to send into space one after the other. The first mission is one of nostalgia: The space janitor will retrieve the first satellite Switzerland ever launched, Swisscube.
In a video, the director of the Swiss Space Center, Volker Gass, said the amount of space junk is getting out of hand. “Something has to be done about this problem. Collisions between satellite and debris are bound to happen. There’s going to be an avalanche effect, and more satellites are going to be destroyed,” Gass said.
This big clean-up plan is also set to launch in 2015.
3. Fishing Nets
In 2011, it was reported that The Japan Aerospace Exploration Agency teamed up with Nitto Seimo, a manufacturer of fishing nets, to build and deploy a giant net that will sweep up space junk in Earth’s orbit.
It won’t be bringing the mess back to Earth, though. The plan is to stretch the thin metal net into space, collecting waste as it moves along for several weeks. After the journey, an electric charge to the net will draw it back toward Earth, burning up both the net and its contents upon entering the atmosphere. (Details for how the net will be guided to gather trash and avoid things we might actually want in orbit are not available.)
Nitto Seimo has spent six years developing the net, which sounds like something out of science fiction.
4. Galactic Garbage “Trucks”
The European Space Agency has a plan, too. Their initiative just isn’t as far-fetched as the others.
According to the ESA, space junk has increased by 50 percent in the past five years, and they’re afraid of future collisions—those by debris alone and those between debris and a working satellite or active mission. The agency wants to tackle the problem directly by sending out missions dedicated to removing litter.
In 2015, the ESA has plans to launch ATVs (Automated Transfer Vehicles), which are unmanned cargo freighters equipped with optical sensors that could be able to detect orbiting trash, gather it, and return it to Earth.
NASA just wants to use lasers. But they don’t want to zap the garbage and destroy it—they want to nudge debris out of the way.
The debris in space moves at incredibly fast speeds and is extremely dangerous to shuttles, the space station, and satellites. The agency wants to avoid using a laser that would explode any objects, which would only create a bigger mess of smaller (and therefore harder to track) pieces.
Ideally, the laser—which would cost an relatively inexpensive $1 million—would be mounted on one of Earth’s poles, where the atmosphere is thinner. During a launch or to avoid a collision, NASA would send pulses of photo pressure to gently prod objects out of the way.
So far, NASA has only floated this idea; actually building the laser would require international cooperation.