The History of Space Debris

In the past fifty-five years, the space around the Earth has gone from a virtually debris-free environment to a zone cluttered with man-made objects that threaten launches, active satellites, and the International Space Station (ISS). NASA reports that as of 2013, more than 21,000 pieces at least the size of a softball were being tracked, and an estimated 500,000 pieces at least the size of a marble are thought to exist. More than 100 million even smaller objects, ranging down to the size of a tiny fleck of paint, are too small to detect or track. Active satellites, numbering about 1,100, comprise about 6 percent of Earth-orbiting objects; the rest is junk, commonly called space debris. This paper examines what space debris consists of, where it came from, and what problems it is causing. An Empirical Baseline In the first half of the twentieth century, before man-made objects were launched into space, some scientists suggested that the space around the Earth might be littered with undetectably small chunks of natural debris that could hinder manned spaceflight. Some, like astronomer Fred Whipple, were concerned about small meteors streaking past the planet. In 1946, Whipple warned that a spaceship traveling toward the moon would have a one in twenty