Space debris: Track and shoot system that is fast and cheap being studied

An accurate, fast and cheap method of tracking and removing space debris from orbit is being studied by an international team of scientists led by Japan's Riken institute.

Combining data from the super-wide field-of-view EUSO telescope with a high-efficiency laser system that shoots high power beams and removes the objects, the team is confident of removing dangerous debris in low earth orbits.

The intense laser beam when focused on the object will produce high-velocity plasma ablation and reduce its orbital velocity, deflecting it for a reentry into the earth's atmosphere.

A small proof-of-concept experiment is being planned on the ISS, with a small, 20-centimetre version of the EUSO telescope and a laser with 100 fibres.

"If that goes well," says Toshikazu Ebisuzaki who led the effort, "we plan to install a full-scale version on the ISS, incorporating a three-meter telescope and a laser with 10,000 fibers, giving it the ability to deorbit debris with a range of approximately 100 kilometres."

Together the instruments can track and deorbit the most dangerous space debris, around the size of one centimetre. Travelling at 28,160 km/h, even a one centimetre nut can hit with the force of a hand grenade.

The EUSO telescope, developed by Riken, was originally planned to detect ultraviolet light emitted by ultra-high energy cosmic rays entering the atmosphere at night. "We realised," says Ebisuzaki, "that we could put it to another use. During twilight, thanks to EUSO's wide field of view and powerful optics, we could adapt it to the new mission of detecting high-velocity debris in orbit near the ISS."

The CAN laser was originally developed to power particle accelerators and can produce powerful laser pulses at a high repetition rate.

European Space Agency officials have also been testing methods of using "fishing" nets to capture space junk in 2021 as part of the e.Deorbit mission.

Space debris, comprising bits and piece of various man-made objects put in orbit, is often difficult to capture as they circle the planet in different orbits.

Debris dangers
Since 2000, these objects ranging from derelict satellites and rocket parts and small parts have nearly doubled and pose a big danger to space missions. Many of these are the result of collisions between existing junk.

There are an estimated 500,000 pieces of space junk of all sizes orbiting Earth, according to Nasa. At the speed they travel even a tiny fleck of paint can damage other satellites and space equipment.

There are almost 17,000 objects larger than a coffee cup.

Last year, the ISS narrowly escaped being hit by debris from Russian wreckage caused by its Kosmos satellite colliding with an Iridium spacecraft.

Orbits of 800-1,000km that pass over the poles pose the biggest challenge as they contain debris from many of the 5,000 odd satellites launched since the dawn of the space age.

At an astronautical congress at Toronto, experts had voiced concern over the number of CubeSats or mini-satellites being launched which disregard guidelines to de-orbit after 25 years.

They have been involved in more than 360,000 near-collisions with other orbiting objects and are missed by ground radars as they are small.