The European Space Agency's historic comet landing last week drew a global audience, but the event didn't go exactly as planned. The Philae lander was unable to deploy its harpoons into the comet's surface and fell into a crevice on its side. Philae's current location prevents it from getting sunlight to charge its batteries. But if the lander, which already has gathered a large amount of scientific data, can't be made to function again, it will join a vast amount of space debris -- approximately 500,000 pieces of debris -- already orbiting Earth.
Philae is unlikely to join the space debris near Earth, but those roughly 500,000 pieces of debris pose risks that space agencies around the world are actively monitoring.