Inside the Astrotech Payload Processing Facility on Vandenberg Air Force Base in California, the transport canister, at left, is moved across the high bay toward the covered dual spacecraft CALIPSO and CloudSat waiting at right. The canister will be lowered over the spacecraft for the move to Space Launch Complex 2. There the spacecraft will be lifted and mated with a Boeing Delta II rocket for launch on April 21. CALIPSO stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation. It will fly in combination with the CloudSat satellite to provide never-before-seen 3-D perspectives of how clouds and aerosols form, evolve, and affect weather and climate. CALIPSO and CloudSat will join three other satellites in orbit to enhance understanding of climate systems.