Vandenberg Air Force Base, Calif. - In the Astrotech Payload Processing Facility at Vandenberg Air Force Base in California, preparations are under way to fuel NASA's Orbiting Carbon Observatory, or OCO, with hydrazine thruster control propellant. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. The OCO mission will collect precise global measurements of carbon dioxide (CO2) in the Earth's atmosphere. Scientists will analyze OCO data to improve our understanding of the natural processes and human activities that regulate the abundance and distribution of this important greenhouse gas. This improved understanding will enable more reliable forecasts of future changes in the abundance and distribution of CO2 in the atmosphere and the effect that these changes may have on the Earth's climate. The launch of OCO is scheduled for Feb. 23 from Vandenberg.