The right lasers could melt space junk, like satellites, into plasma.
The secret is to concentrate on space junk parts that we can reduce to nothing. Otherwise, blasting the wrong parts can create clouds of small debris.
Just one problem: having a laser to remove space junk also means having a laser that could destroy active satellites.
There are approximately 23,000 pieces of space debris larger than 10 centimeters orbiting Earth, including about 3,000 defunct satellites, according to NASA's Orbital Debris Program Office (ODPO). If any of these bits of space junk slam into each other, the collisions could lead to large swaths of debris that might hinder many space activities, including the use of satellites, for generations.
But a common cancer treatment may turn that troublesome space junk into harmless clouds of particles called plasma, Russian scientists say. Laser ablation—the process of removing materials from a solid surface by irradiating it with a laser beam—can destroy malignant tumors in the human body. It could also obliterate dead satellites.
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It might seem like we can simply point lasers from the ground into space to zap useless satellites, but all satellite parts are different and carry various risks. The solar cells that satellites use for power, for example, could be potentially dangerous. If a laser pings the surface of a solar array, it could eject thousands of shards of glass, creating a cloud of microscopic debris.
But a space-borne laser could get around some of these risks, researchers from Bauman Moscow State Technical University say in a new study in Acta Astronautica. The team has been experimenting with different spacecraft materials to see how each reacts to laser pulse emissions called irradiation.
Lasers originating from Earth are subject to atmospheric interference that can decrease the beam's point accuracy, the scientists say. Space-based lasers, though, could more precisely target satellites while avoiding solar arrays. They'd also require less energy.
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Even better: This process would melt the space debris into harmless plasma, reducing the amount of space junk by volume without adding roaming clouds of much tinier space junk in its place.
Why do we hate space junk so much? Consider this: So many objects in space are extremely fragile, so bumping into even a tiny piece of debris could rip into the sides of functional satellites or even cause explosions. That not only damages the satellites, but also sprays a bunch of micro space junk into orbit.
The International Space Station (ISS) has to dodge these wayward scraps on a semi-regular basis. The ISS has conducted at least 27 collision avoidance maneuvers since 1999, according to Orbital Debris Quarterly News, a publication of NASA's ODPO. Since it takes precious—and pricey—fuel to fire up the eight thrusters on the ISS's attached cargo ship, Progress, to complete a manuever, there's a financial incentive to eliminate space junk, too.
But while the Russian scientists' new process of zapping space junk sounds promising, not all experts are convinced it's necessary.
"There's definitely stuff up there that has cultural value, and obviously I don't want someone to point lasers at them," says Alice Gorman, Ph.D., a space archaeologist and associate professor at Flinders University in Adelaide, South Australia.
Although Gorman studies space junk, she says the term undercuts the potential for the debris to one day have a purpose again. Some zombie satellites could come back online in the future, as they have in the past.
Yet there's an even bigger threat, Gorman says: using space lasers for ill will.
"The problem with the lasers, as with a lot of space junk removal mechanisms, is that if you can remove a piece of junk from orbit, then you can remove a working satellite," Gorman says. "Any system to actively remove orbital debris is also effectively an anti-satellite weapon."
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