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It sounds like an idea for a niche movie aimed at sci-fi anoraks: a floating magnetic net that harnesses tonnes of wayward space junk and makes the overcrowded orbital lanes above Earth’s atmosphere safe for future exploration.

Yet that is what scientists in Japan will have in mind when they put a satellite into orbit on Friday, equipped with an experimental electrodynamic tether they say will give the final frontier a long overdue spring clean.

The Space Tethered Autonomous Robotic Satellite-2 (Stars-2) will be included on a satellite jointly developed by the US and Japan to monitor global rainfall and forecast extreme weather. The equipment will travel into orbit aboard Japan’s H-2A rocket, due to be launched in the small hours from the southern Japanese island of Tanegashima.

Working alongside the Japan Aerospace Exploration Agency (Jaxa), researchers at Kanagawa University developed the tether, made from ultra-thin wires of stainless steel and aluminium, with the help of a Japanese fishing net firm.

According to researchers, the tether, measuring 300m in length when fully extended, will generate electricity along its entire length as it passes through Earth’s magnetic field while in orbit. The electricity will reduce the speed of pieces of junk careering through space – everything from dead rockets to satellites that have ended their missions – and lure them closer to Earth. The cosmic cleanup ends when the clutter burns up harmlessly as it enters Earth’s atmosphere.

“The experiment is specifically designed to contribute to developing a space debris cleaning method,” said Masahiro Nohmi, an associate professor at Kagawa University, who is working with Jaxa on the project. The tether comprises several metal filaments measuring less than 0.1mm in diameter that were developed for Jaxa by Nitto Seimo, a Japanese company that has been making fishing nets for almost a century.

In the forthcoming trial Nohmi’s team will attempt to unfurl the tether in orbit and assess its ability to generate the electricity needed to draw in the detritus.

Decades of space exploration has created a chaotic and dangerous junkyard just above Earth’s atmosphere, raising fears that discarded pieces of hardware – and even flecks of paint – orbiting the planet at high speed could damage active spacecraft. Space agencies have reported the number of objects has significantly increased as more countries pour money into ambitious space programmes.

A Chinese anti-satellite weapons test in 2007 is thought to have added about 3,000 items to the inventory of space clutter, according to Nasa. The risk of accidents was underlined by a collision between US and Russian communications satellites two years later.

A band stretching from about 800km to 1,400km above the Earth’s surface is home to more than 20,000 fragments of junk the size of a softball or bigger, says Nasa. If smaller items are included, the number runs into the tens of millions.

The experiment, which has been five years in the making, won’t harness any debris, but if all goes to plan future tests could include a practical demonstration. Full deployment is planned for 2019.

Source: http://www.theguardian.com/science/2014/feb/27/scientists-japan-stars-2-satellite-orbit-space-debris