Stages 1, 2 and 3 of Orbital Sciences’ Taurus XL launch vehicle for NASA’s Orbiting Carbon Observatory, or OCO, have arrived and are prepared for lifting onto Space Launch Complex 576-E at Vandenberg Air Force Base in California. The OCO is an Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. The observatory will collect precise global measurements of carbon dioxide in the Earth's atmosphere. Scientists will analyze the data returned to better understand the natural processes and human activities that regulate the abundance and distribution of this important greenhouse gas. Launch is targeted for 1:51:30 a.m. PST Feb. 24. Photo credit: VAFB