Tags: Debris, Satellite Collision, NASA, DARPA
Publication: Space.com
Publication Date: 01/28/2013

Low Earth orbit, the region of space within 2,000 km of the Earth’s surface, is the most concentrated area for orbital debris. Image credit: NASA Orbital Debris Program Office

Two important orbital debris events have been creating a buzz around the satellite and space industry. First, on Jan. 11 2007, China conducted an anti-satellite test that created more than 100,000 pieces of debris. Second, on Feb. 10, 2009, a defunct Soviet Union-era satellite collided with an operating American spacecraft. They represent the worst satellite breakups in history, according to NASA.

Together, both events created more than a third of the total debris accounted for in low-Earth orbit, where approximately 500 operational spacecraft transit daily. The U.S. Space Surveillance Network (SSN) has catalogued a total of 5,579 fragments, 5,000 of which still remain in orbit as of this month. The SSN monitors the fragments to help provide save passage of the spacecraft traversing those orbits.

Unfortunately, the SSN only tracks fragments more than 4 inches long, but there are hundreds of thousands or more pieces of space debris smaller than that, down to about one millimeter in size.

Scientists are concerned about how the solar cycle will affect space debris. Increased solar activity heats the Earth’s atmosphere, causing it to expand and becomes more dense. This increases drag on space junk, as well as satellites, causing these objects to fall back to Earth more quickly. However, NASA estimates that the peak in solar activity expected in 2013 might be the lowest in 100 years.

In any case, the issue of orbital debris has increasingly captivated the attention of the international community, which has already started to offer plausible solutions such as DARPA’s Phoenix project and the Canadian-American tests to refuel satellites in orbit.

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