Japan Eyes Laser to Get Rid of Dangerous Space Junk

From magnets to harpoons, various methods have been proposed and tested over the years to eliminate the growing problem of space junk. One researcher is leading efforts in a more sci-fi direction: lasers.

Space junk is a well-documented and growing problem. Now more than ever, modern life is underpinned by the thousands of satellites that orbit our planet, providing location data for our GPS systems, military intelligence, and telecommunications.

But satellites don't last forever, and when they inevitably break they remain speeding round the Earth until trace amounts of resistance eventually slows them down enough to re-enter the atmosphere and burn up. This whole process can take years.

Yet satellites are only one small part of the wider space junk issue. Rockets in space inevitably release small pieces of debris here and there, but even a one-inch shard of metal can pose a serious problem if it impacts the International Space Station at several thousand miles per hour.

In more than 60 years of space activities, more than 6,000 launches have resulted in over 28,000 objects in orbit that we're still tracking right now, according to the European Space Agency (ESA). Some of these objects are as small as 5 cms (2 inches).

Satellites only represent around 4,000 or so of this total number, but removing non-operational ones is at least a place to start on the path to cleaning up the mess we've made.

Tadanori Fukushima is a project leader at the Satellite Orbital State Control Laser Laboratory within the Japanese satellite communications company SKY Perfect JSAT.

As the lab's name suggests, Fukushima's goal is to develop a laser-based method of dealing with the space junk problem.

His proposed method involves firing laser beams at the surface of a piece of space debris, heating up its surface. The idea is that the resulting energy would be sufficient to cause the object's orbit to rise.

This might sound counter-intuitive at first since it would mean the object would be pushed further away from Earth's atmosphere where it would burn up. However, by raising an object's orbit high enough it is possible to put it into what's known as a "graveyard orbit"—a region of space in which it will orbit the Earth far away from the areas where commercial orbits tend to be.

In other words, the space junk is still there, but at least it's not causing any immediate issues.

The project is still experimental, but Fukushima plans to test it in space in 2025, press agency AFP reports.

Raising satellites to graveyard orbits is something that satellite operators already do if they're operating in high-altitude Geosynchronous Earth Orbit (GEO) regions. Three months before the satellite is due to be decommissioned, operators will use the last of its fuel to power a small thruster that blasts it up out of a usable orbit.

This means sacrificing "considerable revenue" on the part of the operators according to ESA. "However, today, this is the only possibility for preserving the unique resource of the geostationary ring," the space agency states on its website.

Earlier this year China took a different approach, deploying a large space sail to slow down a rocket using atmospheric drag, accelerating the process of slowing down its orbit so it could reach Earth's atmosphere and burn up faster.

Satellite in space
A stock illustration depicts a satellite orbiting the Earth. Space junk can pose a threat to both other satellites and manned spacecraft. 3DSculptor/Getty