VANDENBERG AIR FORCE BASE, Calif. -- On Launch Complex 576-E at Vandenberg Air Force Base in California, the crane, at left, is attached to NASA's Orbiting Carbon Observatory, or OCO, upper stack to lift and attach the spacecraft to Orbital Sciences' Taurus XL rocket's Stage 0 (within the scaffolding). A portion of the umbilical tower (above it) is attached to the upper stack. The upper stack consists of Stages 1, 2 and 3 of the Taurus as well as the encapsulated OCO spacecraft. OCO is scheduled for launch aboard the Taurus Feb. 24 from Vandenberg. The spacecraft 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. Photo credit: NASA/Dan Liberotti, VAFB KSC-2009-1718