Monday, January 20, 2014

Space Tethers as an Orbital Debris Removal Technique

          by Sarah Ansari-Manea

Space tether. Graphic c/o Wikipedia.
Japan has begun trials utilizing a new method of space cleanup to begin to deal with the large amounts of space debris accumulated around the planet since the start of the space race.

As outlined in the January 15th, 2014 Yahoo News article "Japan scientists test tether to clear up space junk," the new technique will utilize an electrodynamic space tether made from thin wires of stainless steel and aluminium, which will attract dead satellites and other debris magnetically. The electricity generated by the tether as it swings through the Earth's magnetic field will also have a slowing effect on the space junk, which will cause the orbit to decay and the space junk to eventually burn up in the Earths atmosphere.

The tether, designed and built by a team of researchers at Kagawa University for the Japan Aerospace Exploration Agency (JAXA) using techniques derived from Japanese fishing equipment manufacturing firm Nitto Seimo, is expected to be launched into orbit aboard a Japanese rocket in February 2014.

"The experiment is specifically designed to contribute to developing a space debris cleaning method," according to Masahiro Nohmi, an associate professor at Kagawa University.

Of course, Japan isn't the only country aware of both the dangers of orbital debris and the potential of tethers. As outlined in the January 16th, 2014 Bloomberg article "Cleaning up the Final Frontier," at least one other commercial NewSpace company, Tethers Unlimited, has come to much the same conclusion. Others have also looked into the problem, as outlined in the October 3rd, 2013 Popular Science article "5 High-Tech Space-Junk Solutions."

But the current interest isn't just academic. It's driven by an exponential increase in the number of unnecessary artificial objects soaring around since the dawn of the space age. In 2009 NASA estimated that there were approximately 19,000 pieces of non-functioning, man-made and track-able pieces of  “junk” currently in orbit and many more smaller objects with the potential to damage or destroy, according to the April 2009 NASA media briefing on "The Threat of Orbital Debris and Protecting NASA Space Assets from Satellite Collisions." 

The report also indicated that potential collision warnings between space debris, operational and inactive satellites, manned spacecraft and even the International Space Station (ISS) are issued regularly, particularly in low Earth orbit and at the poles where orbits are more likely to overlap.

Even so, there have been at least four major collisions in the last few years according to the April 27th, 2013 EarthSky article "Space junk headed for a cascade of collisions." NASA and other international space organizations have developed a specific set of guidelines to determine whether maneuvering is necessary to avoid collisions, and have agreed to follow UN guidelines in a preventative attempt to minimize space clutter.

But even with the collisions and frequent scares, engineers and scientists are slow to react to the orbital junk issue, and those leading the charge have little support. It is proving to be hard to justify the billions of dollars that would be expended on a cleanup project of this magnitude.

The really hard part is trying to convince other countries that your garbage truck in space will be used for the peaceful purposes stated—and not to mess with other people’s satellites,” says Dave Baiocchi, an engineering professor at the Pardee RAND Graduate School.

Sarah Ansari-Manea.
If space travel and exploration is to continue, cleanup, or at least a stricter international set of guidelines in space waste management, must be considered. At the current rate of orbital debris accumulation, space travel will be incredibly difficult and dangerous in the future.

Sarah Ansari-Manea is an aspiring astrophysicist, currently completing a specialist in physics and astronomy at the University of Toronto.

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