CAPE CANAVERAL, Fla. -- In Building 1555 at Vandenberg Air Force Base in California, workers do a fit check on the mating of the Stage 1 to Stage 2 motors for the Taurus XL rocket that will launch NASA's Orbiting Carbon Observatory, or OCO, spacecraft. At right can be seen the avionics shelf. The avionics skirt, a graphite/epoxy structure, supports the avionics shelf and carries the primary structural loads from the fairing and payload cone. The aluminum avionics shelf supports the third stage avionics. The OCO is a new Earth-orbiting mission sponsored by NASA's Earth System Science Pathfinder Program. The launch of OCO is targeted for January. Photo credit: NASA/Randy Beaudoin, VAFB KSC-08pd3868