Many tons of dust grains, including samples of asteroids and comets, fall from space onto the Earth’s atmosphere each day. An even larger amount of spacecraft debris particulates reenter the Earth’s atmosphere every day. Once in the stratosphere this ‘cosmic dust’ and spacecraft debris joins terrestrial particles such as volcanic ash, windborne desert dust and pollen grains. High flying aircraft with special sticky collectors capture this dust as it falls through the stratosphere, before it becomes mixed with Earth dust. The ultra-clean Cosmic Dust Laboratory, established in 1981 to handle particles one-tenth the diameter of a human hair, curates over thousands of cosmic dust particles and distributes samples to investigators worldwide.