Orbital debris is increasingly becoming a hazard to satellites and other spacecraft, which is why various groups have proposed concepts such as gas clouds, nets and sails for collecting it. While those approaches could capture larger objects, the problem of smaller pieces of debris – which whiz around the Earth like bullets – would remain. That's why an international group of scientists is developing a system that could shoot those bits down with a laser.
The space-based system would consist of two main components: a super-wide field-of-view telescope developed by the EUSO team at Japan's Riken research institute, and a highly-efficient fiber optic-based laser.
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The telescope was originally developed to detect ultraviolet light emitted produced by ultra-high-energy cosmic rays entering the Earth's atmosphere at night. EUSO's Toshikazu Ebisuzaki, who is leading the project, realized that it could also be adapted to detect high-velocity debris fragments at twilight.
Once a piece was spotted and located, the system would instruct the laser to focus intense pulses of light onto it. In a process known as plasma ablation, this would cause the one side of the object to heat up and turn to plasma. As the plasma plumed off to that side, it would create thrust, sending the debris down to burn up in the atmosphere.
Plans now call for a proof-of-concept model to be installed on the International Space Station. It will utilize a 20-cm telescope and a 100-fiber laser, and will concentrate on shooting down debris near the station. If that goes well, it could be replaced with a full-scale version that has a 3-meter telescope, a 10,000-fiber laser, and a range of 100 km (62 miles).
Down the road, another system could be deployed to an altitude of 800 km (497 miles) above the Earth's surface, where a greater amount of debris is present.
"Our proposal is radically different from the more conventional approach that is ground based, and we believe it is a more manageable approach that will be accurate, fast, and cheap," said Ebisuzaki. "We believe that this dedicated system could remove most of the centimeter-sized debris within five years of operation."
Along with Riken, other institutes taking part in the project include the University of California at Irvine, the University of Paris, and the University of Torino.
A paper on the research was recently published in the journal Acta Astronautica.