Japan Fishes Space Junk, Cleans Up the Atmosphere

space junk

Earth’s space junk is reaching a critical point. Soon new satellites will have a difficult time finding orbits that will not put them on an eventual collision course with space junk, and Japan has initiated a program to clean up the atmosphere by fishing for space-debris. Currently, more than 20,000 pieces of space junk, with a combined weight of 5,500 tons, orbit the earth. Japan’s plan is to send space craft outfitted with wide nets into the outer atmosphere to fish out the junk.

Japan’s JAXA space agency and Kagawa University are responsible for the enterprise, which will launch a test run at the end of February. The test run will have two main objectives, according to Kagawa University’s associate professor and spokesperson for the space debris cleaning project, Masahiro Nohmi. The first objective is to test the extension of a 300-meter tether in orbit. The second objective is to observe the transfer of electricity.

The tether, fashioned by a Japanese fishing net manufacturer, is made from thin stainless steel and aluminum wires and is called an electrodynamic tether. The tether uses an electromagnetic charge to attract metal space junk it comes in contact with. When the tether attached itself to a piece of space junk, the junk is redirected toward the earth by means of electricity.  Because the tether generates electricity as it travels though the earth’s magnetic field, space junk should be slowed down, which should pull the junk into lower and lower orbits until the junk enters the atmosphere and burns up harmlessly.

Currently, the approximately 22,000 pieces of space junk that fly around the earth’s atmosphere are mapped by computers, and new satellites are projected along courses calculated to avoid the orbits of space junk and other satellites. In addition to the 22,000 significant pieces of space junk, another 500,000 small bits of space junk between 1 cm and 10 cm also remain in orbit. Many pieces of space junk are created through collisions. Space junk travels at speeds around 30,000 km/hour.

Currently, there are over 1000 operational satellites above the earth. Half of these satellites are only a few hundred kilometers above the earth’s surface in the Low-Earth Orbit, including the International Space Station and the Hubble Space Telescope. At 20,000 kilometers above the surface, in the Medium-Earth Orbit, GPS and navigation satellites account for around 20 percent of the 1000-plus operational satellites. At 36,000 kilometers, the rest of the satellites are in geostationary orbit.  Currently, there is so much junk in space that the International Space Station must move to avoid dangerous impacts. This mass of garbage threatens future space missions.

The test run for Japan’s project to clean up the atmosphere by fishing space-junk is scheduled to launch February 28, 2014. The tether will be unfurled from a satellite developed by Kagawa University. The Feb. 28 test run will not attempt to reel in any space-junk, but future missions will make such attempts. The next phase of the project includes a net 2/3 of a mile long that has already been manufactured by JAXA. Future plans include even longer tethers that will collect entire rocket stages and other large pieces of space debris which are cluttering up the earth’s atmosphere, posing a hazard to working equipment.

By Day Blakely Donaldson


South China Morning Post
Universe Today

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