Earth observation system (EOS) is proved to be the most efficient to yield information about Earth's land, atmosphere, ice, oceans and life that is obtainable in no other way, and ensures the development of earth system science. For a long time, people have expected to understand global changes, which require global-scale observations and models, and many regional and local changes are only truly understood when seen in their global context. Research conducted by the Earth Science Enterprise advances the interdisciplinary field of Earth system science and contributes to NASA's mission to understand and protect our home planet. Earth observing system, using the vantage point of space, is providing an understanding of our home planet that could never be achieved if we were bound to Earth's surface. Based on the last half a century development of the Earth observation techniques and the requirement of data collection in the study of the Earth system science, NASA started to plan the EOS programs at the beginning of the 1980's, and put it in practice at the beginning of the 1990's. EOS programs define a series of satellites, natural science knowledge according to system in the next ten years separately, and the launching of sun-synchronous satellites series is the essential part. The evolution process from the EOS program to the Earth science enterprise (ESE) was presented. ESE answers a series of scientific questions by observing, modeling the processes and controlling the Earth system. The ESE defines the aims of science, application and technology, and arranges different satellite missions according to different science questions. Based on the ESE strategy, the future development of EOS was evaluated. So far, Terra, Aqua and Aura have been launched successfully already, which attract the interest of the remote sensing research. The wealth of Earth system data we provide to government agencies, universities, and private industry allows for better research, exploration, and improvement in essential services such as weather forecasting, seasonal climate prediction, climate change assessment, aviation safety, natural resources management, agricultural management, and infrastructure planning.