Aqua is a major satellite mission of the Earth Observing System (EOS), an international program centered at the U.S. National Aeronautics and Space Administration (NASA). The Aqua satellite carries six distinct Earth-observing instruments to measure numerous aspects of Earth's atmosphere, land, oceans, biosphere, and cryosphere, with a concentration on water in the Earth system. Launched on May 4, 2002, the satellite is in a Sun-synchronous orbit at an altitude of 705 km, with a track that takes it north across the equator at 1:30 p.m. and south across the equator at 1:30 a.m. All of its Earth-observing instruments are operating, and all have the ability to obtain global measurements within two days. The Aqua data will be archived and available to the research community through four Distributed Active Archive Centers (DAACs).