On Launch Complex 576-E at Vandenberg Air Force Base in California, Orbital Sciences Engineer Jose Castillo maneuvers the bucket truck at right into position over the fairing access door on NASA's Orbiting Carbon Observatory, or OCO. Glenn Weigle of Orbital Satellite Systems Group is on the bucket at left. Weigle is prepared to move in and inspect the GN2 instrument purge flow. OCO 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. OCO is scheduled to launch Feb. 24 aboard an Orbital Sciences' Taurus XL rocket. Photo credit: NASA/Richard Nielsen, KSC