Stage 0 of the Taurus XL launch vehicle for the Orbiting Carbon Observatory arrives at complex 576E at Vandenberg Air Force Base in California. It will be mated with stages 1, 2 and 3 for the launch of OCO. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. It is scheduled to launch Feb. 23. Photo credit: NASA/Randy Beaudoin, VAFB