The tri-agency Integrated Program Office (IPO) manages the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the Defense Meteorological Satellite Program (DMSP) and Polar-orbiting Operational Environmental Satellites (POES) that have provided global data for weather forecasting and environmental monitoring for over 40 years. Beginning in late 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. NPOESS will observe more phenomena simultaneously from space than its operational predecessors and deliver a data volume significantly greater than the POES and DMSP systems with substantially improved delivery of data to users. Higher (spatial, temporal, and spectral) resolution and more accurate imaging and sounding data will enable improvements in short- to medium-range weather forecasts. NPOESS will support the operational needs of meteorological, oceanographic, environmental, climatic, and space environmental remote-sensing programs and provide continuity of data for climate researchers. With the development of NPOESS, we are evolving operational "weather" satellites into integrated global environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system-atmosphere, ocean, land, and the space environment.
The NPOESS (National Polar-orbiting Operational Environmental Satellite System) program represents the merger of the NOAA POES (Polar-orbiting Environmental Satellite) program and the DoD DMSP (Defense Meteorological Satellite Program) satellites. Established by presidential directive in 1994, a tri-agency Integrated Program Office (IPO) in Silver Spring, Maryland, has been managing NPOESS development, and is staffed by representatives of NOAA, DoD, and NASA. NPOESS is being designed to provide 55 atmospheric, oceanographic, terrestrial, and solar-geophysical data products, and will disseminate them to civilian and military users worldwide. The first NPOESS satellite is scheduled to be launched late in this decade, with the other two satellites of the three-satellite constellation due to be launched over the ensuing four years. NPOESS will remain operational for at least ten years. The 55 Environmental Data Records (EDRs) will be provided by a number of instruments, many of which will be briefly described in this paper. The instruments will be hosted in various combinations on three NPOESS platforms in three distinct polar sun-synchronous orbits. The instrument complement represents the combined requirements of the weather, climate, and environmental remote sensing communities. The three critical instruments are VIIRS (Visible/Infrared Imager-Radiometer Suite), CMIS (Conical Microwave Imager/Sounder), and CrIS (Cross-track Infrared Sounder). The other IPO-developed instruments are OMPS (Ozone Mapper/Profiler Suite), GPSOS (Global Positioning System Occultation Sensor), the APS (Aerosol Polarimeter Sensor), and the SESS (Space Environment Sensor Suite). NPOESS will also carry various "leveraged" instruments, i.e., ones that do not require development by the IPO. These include the ATMS (Advanced Technology Microwave Sounder), the TSIS (Total Solar Irradiance Sensor), the ERBS (Earth Radiation Budget Sensor), and the ALT (Radar Altimeter).