The National Oceanic and Atmospheric Administration (NOAA), Department of Defense (DoD), and National Aeronautics and Space Administration (NASA) are working with prime contractor Northrop Grumman Space Technology (NGST) and its subcontractors to jointly develop the next-generation operational weather and environmental satellite system - the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will consist of four spacecraft (C1 – C4) and associated sensors in two orbits (1330 local time ascending node – LTAN and 1730 LTAN). The afternoon NPOESS spacecraft will carry the following four primary instruments: Visible/Infrared Imager Radiometer Suite (VIIRS); Cross-track Infrared Sounder (CrIS); Advanced Technology Microwave Sounder (ATMS), and Ozone Mapping and Profiler Suite (OMPS). In addition, the afternoon NPOESS spacecraft will carry the Microwave Imager/Sounder (MIS – C3 only), Space Environment Monitor (SEM), Clouds and the Earth's Radiant Energy System (CERES – C1 only), and Total Solar Irradiance Sensor (TSIS – C1 only). Currently, the early-morning spacecraft will fly with a reduced complement of instruments: VIIRS and MIS (C2 and C4). Both early-morning and afternoon spacecraft will also be equipped with the Advanced Data Collection System (ADCS) and Search and Rescue Satellite Aided Tracking System (SARSAT).

A mid-morning orbit (2130 LTAN) will be occupied by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Meteorological Operational (MetOp) spacecraft that carries advanced instruments similar to those that will fly on NPOESS. EUMETSAT's MetOp-A which was launched in October 2006, permanently replaced NOAA's Polar-orbiting Operational Environmental Satellite (POES) in the mid-morning orbit as part of the NOAA/EUMETSAT Initial Joint Polar-orbiting Operational Satellite System (IJPS). The joint constellation of NPOESS and MetOp satellites will allow the international community to realize global coverage from advanced atmospheric imaging and sounding instruments with a data refresh rate of approximately four to six hours.

The NPOESS Preparatory Project (NPP) that is jointly managed by the NPOESS Integrated Program Office and NASA is scheduled to be launched at the turn of the decade. NPP will carry five NPOESS sensors (VIIRS, CrIS, ATMS, OMPS, and CERES) to provide on-orbit testing and validation of sensors, algorithms, ground-based operations, and data processing systems prior to the launch of the first operational NPOESS satellite. The NPP satellite will be launched into the 1330 LTAN orbit to reduce the risk of a data gap between the last POES and the first NPOESS satellite. NPP will also provide a “bridge” from NASA's Earth Observing System (EOS) research missions to the operational NPOESS mission. Flight units for the NPP instruments are nearing completion and undergoing final characterization and calibration prior to integration onto the NPP spacecraft.

The first NPOESS spacecraft is scheduled for launch in 2013. The last satellites in the two-orbit NPOESS constellation are expected to continue operations until about 2023-2026. NPOESS is on track to deliver essential measurements for operational weather and ocean nowcasting and forecasting, land use, and space weather while providing continuity of data for 14 of 26 essential climate variables. Although several NPOESS climate sensors were de-manifested as a result of restructuring in 2006, the NPOESS spacecraft is designed to handle the re-manifest of all de-manifested sensors, including climate monitoring sensors. As a result of recent tri-agency decisions, CERES was added to NPP and both CERES and TSIS will be flown on NPOESS C-1. NOAA and NASA are currently working on other options to meet requirements for long-term climate monitoring from space that may include NPOESS.

Key components of the NPP and NPOESS command, control, and communications system have already been installed and have passed preliminary tests at the Svalbard Satellite station (SvalSat) and at NOAA's Satellite Operations Facility. Communications capabilities from Antarctica are being upgraded to support NPOESS. NOAA and EUMETSAT are currently exploring opportunities to receive MetOp data from an Antarctic ground station, thereby substantially improving data latency in the mid-morning orbit. Installation and testing of the NPOESS Integrated Data Processing system at NOAA and DoD facilities will be completed in 2008, well in advance of the planned launch of NPP.

NPOESS will deliver higher spatial, temporal, and spectral resolution data with significantly improved data latency to enable civilian and military users to realize major benefits throughout a wide range of operational and research applications. For the civil sector, NPOESS data will improve the timeliness and accuracy of weather warnings and forecasts; contribute to increased safety of the transportation industries, and provide valuable terrestrial and atmospheric data and products for assessing the health of worldwide agricultural production. For the military, NPOESS products will provide more accurate and timely information on surface, atmospheric, marine, and near-Earth space environmental conditions to support the full spectrum – land, air, sea, and space – of military operations. As a key component of the Global Earth Observation System of Systems (GEOSS), NPOESS will contribute to the “Nine Societal Benefits Areas.” NPOESS will provide essential real-time data to the international community to support weather forecasting, as well as continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales.