The Orbiting Carbon Observatory is the latest mission in NASA"s ongoing study of the global carbon cycle. It is the first spacecraft dedicated to studying atmospheric carbon dioxide, the most significant human-produced greenhouse gas and the principal human-produced driver of climate change. Mission data will be used by the atmospheric and carbon cycle science communities to improve global carbon cycle models, reduce uncertainties in forecasts of how much carbon dioxide is in the atmosphere, and make more accurate predictions of global climate change.