VANDENBERG AFB, CALIF. - Inside the gantry on the SLC-2 launch pad, the second stage of a Delta II rocket is lowered for mating with the first stage, below. The Delta II will launch the Aqua-EOS satellite. Aqua is one of a series of spacebased platforms that are central to NASA's Earth Science Enterprise (ESE), a long-term study of the scope, dynamics and implications of global change. The Aqua program is composed of Aqua and other spacecraft (including Terra and Aura) and a data distribution system (ESDIS, and Mission Operations Center Implementation Team). Flying in an orbit that covers the globe every 16 days, Aqua will provide a six-year chronology of the planet and its processes. Comprehensive measurements taken by its onboard instruments will allow multidisciplinary teams of scientists and researchers from North and South America, Asia, Australia and Europe to assess long-term change, identify its human and natural causes and advance the development of models for long-term forecasting. Launch is scheduled for April 26 from Vandenberg KSC-02pd0404