The Aqua mission builds on NASA's long history of studying the Earth and its atmosphere from the impressive perspective of space. NASA scientists and others have been doing such studies since the 1960s, and the efforts by now have matured to the point where many Earth science elements are being studied together as a global system. Earth System Science integrates several important scientific disciplines, including meteorology, atmospheric chemistry, oceanography, glaciology, hydrology, and biology. Amongst the aims are an integrated understanding of the Earth system at present, an improved understanding of the prominent changes the system has undergone in the past, and improved predictions regarding how the system is likely to change in the future. Satellites contribute toward these goals by enabling the collection of global data sets that would be impractical through any other available means.