The National Aeronautics and Space Administration (NASA) Earth science flight program is a dynamic undertaking that consists of a large fleet of operating satellites, an array of satellite and instrument projects in various stages of development, a robust airborne science program, and a massive data archiving and distribution system. Each element of the flight program is complex and presents unique challenges. NASA builds upon its successes and learns from its setbacks to manage this evolving portfolio to meet NASA's Earth science objectives. NASA fleet of 19 operating missions provides a wide range of scientific measurements obtained from dedicated Earth science satellites and from instruments mounted to the International Space Station (ISS). Projects in development are divided into two broad categories: systematic missions and pathfinders. The Earth Systematic Missions (ESM) program includes a range of multi-disciplinary Earth-observing research satellite missions aimed at understanding the Earth system and its response to natural and human-induced forces and changes. The Earth System Science Pathfinder (ESSP) program provides frequent, regular, competitively selected Earth science research opportunities that accommodate new and emerging scientific priorities and measurement capabilities. The Earth Science Airborne Science Program provides manned and unmanned aircraft systems that further science and advance the use of satellite data. NASA uses these assets worldwide in campaigns to investigate extreme weather events, observe Earth system processes, obtain data for Earth science modeling activities, test and refine new instrument technologies, and calibrate instruments flying aboard Earth science spacecraft. Through the Earth Observing System Data and Information System (EOSDIS) NASA's Earth Science Division acquires, preserves, and distributes observational data from operating spacecraft to support Earth Science research focus areas. In addition, the Earth science flight program benefits from investments by the Earth Science Technology Office (ESTO) to develop and demonstrate cutting-edge technologies that can be reliably applied to the diverse needs of future NASA Earth science measurements and mission. NASA's current Earth Science portfolio is responsive to national scientific priorities. As the program evolves into the future, it will leverage the lessons learned from the current missions in operations and development, and plan for adjustments to future objectives in response to the needs of the United States and the Earth science community.