March 22, 2013
How To Remove Orbital Debris With Less Risk
Lee Rannals for redOrbit.com — Your Universe Online
An article coming out in the Journal of Spacecraft and Rockets pitches ideas to attempt to remove orbital debris with less risk.The article, authored by Kerry Nock and Dr. Kim Aaron, of Global Aerospace Corporation (GAC), and Dr. Darren McKnight, of Integrity Applications Incorporated, Chantilly, VA, compared in-orbit debris removal options regarding their potential risk of creating new orbital debris or disabling working satellites during deorbit operations.
Space debris is a growing problem that has been discussed and studied for years and has lead to guidelines and policies. The number of significant satellite breakup events has averaged about four per year.
Removing large amounts of material in orbit has been a major issue for debris mitigation strategies because a large object is not only more likely to be involved in a collision in orbit, but its mass has the potential to be the source of a large amount of small debris.
The authors discussed deorbit devices that use large structures to interact with the Earth's atmosphere, magnetic field or its solar environment to bring defunct spacecraft out of orbit. They say some devices may be better than others due to their size and likelihood of colliding with other spacecraft during their operation.
According to the report, other risks deorbit devices face are the nature of hypervelocity impacts and the level of solar activity. The authors describe the physics of hypervelocity impacts in space that can affect the assessment of risk. Also, they wrote about how solar activity level affects the decay processes and alters the result of the calculation of collision cross-section area times decay time.
They concluded ultra-thin, inflation-maintained drag enhancement devices pose the least risk of creating new debris or disabling operating satellites. However, they also pointed out all deorbit devices studied have less risk than just leaving an object in orbit.
"As the orbital debris hazard increases, it will be critical that the community can use techniques that have high operational effectiveness and low risk. Inflatables have been the best balance for that approach in my mind and I hope that this paper exposes more of the aerospace industry to the benefits of using inflatables to accelerate the reentry of non-operational spacecraft," said Dr. McKnight.
In January, a piece of space debris generated by China in January 2007 collided with Russia's BLITS satellite. The collision affected both the satellite's orbit and its rate of rotation. The detonation of China's FENGYUN satellite in 2007 created over 2,300 pieces of debris big enough to be tracked from the ground.
“To put the overall risk in some perspective, of the 3,150 payloads in Earth orbit or beyond, we have orbital data for 2,782 of those,” NASA technical program manager T.S. Kelso told NBC News in an e-mail. “Of the missing 368 payloads, some are in deep-space orbits around the sun or other planets, and some are not released by the US government for whatever reason. Of the 2,782 payloads we do have data for, 1,860 payloads pass through the regime now affected by the debris from the Chinese ASAT test."
Getting the jump on space junk now is crucial to ensure future generations are able to use the luxuries Earth's orbit has to offer.