How Much Junk Is in Space?

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Two NASA chase planes capture the European ATV space cargo ship breaking up in the atmosphere upon successful re-entry and completion of the mission.
(Image credit: ESA/NASA)

Space, a seemingly vast frontier, is actually pretty crowded with junk, and it's getting worse.

There are about 500,000 known pieces of space junk down to items about 0.5 inches (1.27 centimeters) wide in orbit. Of those, about 21,000 objects are larger than 4 inches (10.1 cm) in diameter, and are being tracked by the Department of Defense's U.S. Space Surveillance Network. These are items like spent rocket stages and broken satellites such as Galaxy 15.

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Clara Moskowitz
Clara has a bachelor's degree in astronomy and physics from Wesleyan University, and a graduate certificate in science writing from the University of California, Santa Cruz. She has written for both Space.com and Live Science.