The Mad Plan to Clean Up Space Junk With a Laser Cannon

If a team of astronomers has their way, soon the International Space Station will be outfitted with a new, spiffy laser-wielding telescope.
The Death Star from Star Wars Episode IV  A New Hope.
The mother of all laser cannons, in Star Wars: Episode IV - A New Hope.Lucasfilm

If a team of astronomers has its way, the International Space Station will be outfitted with a spiffy laser-wielding telescope. No, no, hold on---it's not to kill aliens or rebel civilizations. It's to clean up a huge mess.

If anything rivals the human drive for exploration, it is the apparent need to leave a spectacular plume of trash in our wake. In space, the problem is becoming acute. Decades of discarded satellites and unchecked collisions have left some 3,000 tons of debris in orbit. That's roughly 15 blue whales, 600 elephants, or 1,500 cars.

Mankind's slovenly ways threaten our continued use of space-based satellites, which have become a core component of modern technological infrastructure. You've probably used those satellites dozens of ways so far today. Have you sent a text? Watched TV? Used GPS? Checked the weather? If you'd like to keep doing these things, astronomers will soon need to find a way of tidying up low Earth orbit. In that region, between 100 and 1,250 miles above the planet, mere flecks of paint (of which there are many) travel with sufficient force to sever electrical wires, dent spacecraft, and kill astronauts.

Lasers could be the saviors in operation Orbital Clean House. A team of astronomers at Japan's RIKEN, a network of basic-research laboratories, have proposed adding debris-zapping capabilities to a telescope they are already developing for the ISS. They plan to start on a small scale, with a laser no more powerful than the pointer you use to play with your cat. In time, the power could be increased to become a proper laser cannon. (Yes, dear reader, a laser cannon.)

If the notion of lasers in space sounds slightly terrifying, you're not alone. "The problem with it is mostly political," says Don Kessler, who spent more than 30 years at NASA's Johnson Space Center. "Everyone is afraid you are going to weaponize space." Kessler began the field of studying orbital debris and lends his name to "Kessler syndrome," a scenario in which colliding debris begins a cascade of increasing debris and destruction.

If you can take out a derelict satellite or rocket body, you also have the ability to kill a working satellite. And given how important satellites are to militaries, an attack could prompt a war. But if astronomers are going to put a laser cannon anywhere above Earth, the ISS would be the place to do it. Bolting the proposed laser to the ostensibly neutral space station---which already must make frequent maneuvers to avoid larger, tracked pieces of debris---might be a way to make a scientifically sound idea politically sound as well.

For the team at RIKEN, the proposed laser cannon is a way to not only clean up their beloved orbits but also make their telescope, the Extreme Universe Space Observatory, more practically relevant, says project scientist Marco Casolino. With its wide field of view and the ability to register even the quickest flashes of light, the scope would be well suited for spotting debris as it whizzes past the ISS.

Now, the RIKEN team isn't the first to suggest lasers as debris-fighting tools: Scientists have for at least 30 years kicked around the idea of laser-vaporizing an object's surface and knocking it into the atmosphere to burn up. Nor is it the only plan currently in development.

The European Union is supporting a project called Stardust which is analyzing how to handle space debris and threatening asteroids (items they call "non-cooperative targets")---and may settle on lasers as the best plan. Stardust is led by Massimiliano Vasile, of the University of Strathclyde's Department of Mechanical and Aerospace Engineering. Vasile and his team previously came up with a proposal to use a swarm of navigable laser-equipped satellites to launch coordinated attacks against non-cooperative targets. The project was known, appropriately, as Laser Bees.

In the United States, the National Aeronautics and Space Administration---which publishes Orbital Debris Quarterly News, a must read for space junk enthusiasts---proposes fighting space debris with a ground-based laser. (No NASA official could be reached before deadline for comment.) Non-lasery ideas are abundant too, coming in the form of reusable spacecraft launched off modified jumbo jets or electrodynamic space tethers to slow orbiting junk by accosting it with electricity.

But right now, even a debris-fighting proposal less off-the-wall than a laser cannon would have trouble getting off the ground. That's because there's very little momentum behind orbital cleanup projects. "My biggest complaint is that nobody has tested these concepts," Kessler says. "And right now there is absolutely no money being spent by the US to do that."

The world is on the path to industrializing space, Kessler says, without properly acting like it. The way countries and businesses have operated in space so far has created an unstable, chaotic space environment. "Your first clue should be when you look at a picture of our solar system," he says, "everything is in the same plane going the same direction. You look at a picture of the satellites going around the Earth, and they're going every which way."

Laser cannons are one short-term solution, but in the long run, managing low Earth orbit will more than a game of shoot-'em-up. Kessler would like to see the satellites already in space corralled together. New satellites (at least portions) could be constructed by reusing the materials from old satellites.

And eventually, they'd all need to orbit in the same direction, too. Right now, it's all too easy for satellites to run into each other head on (such as when Iridium 33 collided with Cosmos 2251 in 2009, spraying low Earth orbit with tens of thousands of pieces of debris). The current orbit of satellites, Kessler says, looks similar to the early days of the universe. "Everything was running into each other and colliding," he says. Those collisions created a lot of dust. As the dust collided with itself, it decreased the momentum of the orbiting objects to the point where the only stable things that were objects that were moving in the same direction.

"It's the way galaxy formed, it's the way the solar system formed, it's the way the moon formed around our earth," Kessler says. Perhaps mankind could learn something from their ultimate configuration. Until then, bring on the laser cannons.