This month, the U.S. Air Force announced that it will shut down its “radar fence,” which tracks space trash. They cite federal government sequestration as the reason, and lament having to close the fence. Wait, there’s space trash? And it’s important enough to be tracked by the Air Force? Yup.
From flakes of paint shaken off of rockets to the broken up bodies of abandoned satellites, humankind’s machine waste now clutters low-Earth-orbit, the 2000 kilometers (1243 miles) above Earth’s surface. This important zone hosts most of our satellites, including those crucial for conservation and environmental management: the Earth Observing System (EOS) satellites, launched by NASA and used by the Forest Service and environmental science academics. One data collector is MODIS, an imagery sensor that flies on the Terra and Aqua satellites.
“We use MODIS data for fire detection,” says Brad Quayle, a remote sensing specialist for the Forest Service. “We also monitor tree health to keep track of pests and pathogens.” For example, Quayle's team can remotely detect a slight bark beetle outbreak through changes in satellite images of forests.
Without low-Earth-orbit satellites, environmental science would be sent back to the Stone Age, or at least the '60s. Yet Earth’s spacefaring nations have polluted what was once seen as a public good: the "limitless" vastness of space. It took only two acts of human negligence to create one third of the space debris currently tracked by NASA. In 2007 China intentionally smashed a weather satellite, and in 2009 American and Russian communications satellites collided accidentally (see a video reenactment below). Both events scattered thousands of pieces of junk into orbit. The remaining pieces accumulated from rocket stages of human spacecraft, dead satellites left in orbit, and other miscellaneous trash.