MetOp
MetOp (Meteorological Operational) is a series of polar-orbiting satellites developed by the European Space Agency (ESA) in collaboration with EUMETSAT, designed to deliver global observations of Earth's atmosphere, oceans, and land surfaces for improving weather forecasts and monitoring climate change.[1] As part of the European contribution to the Initial Joint Polar-orbiting Operational Satellite System (IJPS) with NOAA, the programme operates in a sun-synchronous orbit at approximately 817 km altitude, providing complementary data to geostationary satellites like Meteosat by covering polar regions and enabling twice-daily global scans.[2] The MetOp programme began with the first-generation satellites, starting with MetOp-A launched on 19 October 2006 from Baikonur Cosmodrome aboard a Soyuz rocket, which operated until its retirement on 30 November 2021 after providing over 15 years of continuous data.[2] This was followed by MetOp-B, launched on 17 September 2012, which remains operational as of November 2025 and has delivered critical measurements despite some instrument degradations over time.[2] MetOp-C, the third first-generation satellite, was launched on 7 November 2018 from Vandenberg Air Force Base on a SpaceX Falcon 9, and it continues to function fully, ensuring data continuity until the mid-2030s.[2] To extend the programme into the future, ESA and EUMETSAT initiated the MetOp Second Generation (MetOp-SG), comprising six satellites divided into two sub-series: three 'A' satellites focused on infrared and visible imaging for atmospheric sounding, and three 'B' satellites equipped with microwave and radar instruments for all-weather observations.[3] The first of these, MetOp-SG A1, was successfully launched on 13 August 2025 from Europe's Spaceport in Kourou, French Guiana, aboard an Ariane 6 rocket; as of November 2025, it is undergoing commissioning with initial instrument data already being transmitted, marking the beginning of enhanced capabilities with a planned operational lifetime of 7.5 years per satellite to cover needs until the mid-2040s.[3][4] Subsequent launches include MetOp-SG B1 in 2026 and MetOp-SG A2 in 2032.[2] The first-generation MetOp satellites each carry a suite of 11 complementary instruments enabling measurements of ozone, trace gases, cloud properties, sea surface temperatures, soil moisture, and vegetation cover.[1] These observations support numerical weather prediction models, extending forecast accuracy up to two weeks, nowcasting for severe weather events, and long-term climate records essential for research on global warming and environmental changes.[2] By integrating data from both morning and afternoon orbits through the IJPS partnership, MetOp enhances global forecast reliability and contributes to international efforts like the Copernicus programme for atmospheric monitoring.[3]Overview
Program Objectives
The MetOp program serves as the space segment of the EUMETSAT Polar System (EPS), establishing Europe's inaugural operational polar-orbiting satellite initiative for delivering near-real-time global observations of the atmosphere, oceans, and land surfaces to aid weather forecasting and environmental monitoring.[2] Its core objectives center on supplying critical meteorological data, including vertical profiles of atmospheric temperature and humidity, concentrations of ozone and trace gases such as carbon dioxide and methane, ocean surface wind vectors, and cloud cover characteristics, all of which are vital inputs for numerical weather prediction (NWP) models to enhance forecast accuracy and nowcasting capabilities for severe weather events.[5] By prioritizing operational meteorology, the program supports global efforts to predict phenomena like storms and extreme weather with greater precision.[2] A key aspect of the MetOp objectives involves fostering international collaboration through the Initial Joint Polar System (IJPS) partnership with the National Oceanic and Atmospheric Administration (NOAA), where MetOp satellites maintain a mid-morning orbit (approximately 09:30 local solar time) to complement NOAA's afternoon orbit, ensuring overlapping and continuous polar coverage for optimized data availability.[2] This cooperative framework, including shared ground infrastructure and instrument contributions, amplifies the program's impact on worldwide operational meteorology by providing complementary observational perspectives that improve the timeliness and completeness of global datasets.[2] Long-term continuity forms another foundational objective, with the first-generation MetOp satellites designed to sustain data provision from 2006 through at least 2028, while the second-generation extension targets uninterrupted service beyond 2039 to build extended time series for climate monitoring and research.[2] These datasets enable applications such as tracking hurricane intensity and paths via ocean wind measurements, assessing air quality through trace gas distributions to inform pollution forecasts, and investigating climate change trends by detecting variations in atmospheric composition and surface conditions over decades.[6][7][5]Constellation Design
The MetOp program employs a dual-satellite strategy within the Initial Joint Polar Satellite System (IJPS), featuring polar sun-synchronous orbits to achieve comprehensive global coverage. European MetOp satellites operate in a morning (AM) orbit with a local descending node time of approximately 09:30, complementing the afternoon (PM) orbit provided by NOAA's Polar Operational Environmental Satellites (POES) and Joint Polar Satellite System (JPSS). This configuration, at an altitude of 817 km and an inclination of 98.7°, enables twice-daily observations of the Earth's surface, including polar regions, supporting numerical weather prediction and climate monitoring.[8][2] For the first generation, the constellation consists of three satellites—MetOp-A, MetOp-B, and MetOp-C—designed to provide continuous operations for over 15 years through sequential launches spanning more than a decade. All three satellites fly in the AM sun-synchronous orbit, ensuring redundancy and sustained data availability while relying on NOAA's PM satellites for the complementary overpass. This architecture maximizes temporal sampling for atmospheric and surface observations, with the satellites phased to avoid overlap and maintain even coverage.[8][2] The transition to the second generation, MetOp-SG, involves an expanded constellation of six satellites—three A-type (morning orbit) and three B-type (afternoon orbit)—beginning with the launch of MetOp-SG A1 on 13 August 2025. As of November 2025, MetOp-SG A1 is undergoing commissioning. This setup maintains the core orbital parameters of 98.7° inclination but operates at an altitude of approximately 832 km, introducing enhanced spatial resolution and spectral capabilities for improved global coverage, including faster revisit times and additional environmental parameters. The A-type satellites continue the AM role akin to the first generation, while B-type satellites assume PM responsibilities previously filled by NOAA, fostering greater European autonomy within the ongoing IJPS collaboration.[9][10][11] Joint operations with NOAA's JPSS and POES ensure seamless data integration, with shared ground segments, instrument interoperability, and coordinated launches to sustain the dual-orbit framework beyond the first generation. First-generation satellites have a minimum design lifetime of 5.5 years, while second-generation satellites have a nominal operational lifetime of 7.5 years, incorporating redundancies such as dual propulsion systems and robust power subsystems to support mission extensions often exceeding a decade.[8][2][10]Background
Development History
The MetOp program was initiated in September 1998 by the European Space Agency (ESA) and EUMETSAT as part of the EUMETSAT Polar System (EPS), Europe's first program for operational polar-orbiting meteorological satellites, with a total cost for the first generation exceeding €2.5 billion covering satellite development, launches, and ground operations.[12][13] The program aimed to provide continuous morning-orbit observations in coordination with U.S. afternoon-orbit satellites to support global numerical weather prediction and climate monitoring. Key milestones included the start of EPS program activities and Phase C/D development in late 1998, following earlier feasibility studies, with the prime contract for the satellite platform's service module awarded to Thales Alenia Space (formerly Alcatel Space) in 2001.[14] Phase A/B feasibility and preliminary design studies were conducted from approximately 1999 to 2001 to define the system architecture and instrument suite. The first satellite, MetOp-A, was launched successfully in October 2006, marking the operational handover to EUMETSAT for control and data dissemination later that year.[8] International partnerships were central to the program's success, including co-development with NOAA for shared instruments such as the Advanced Microwave Sounding Unit-A (AMSU-A) and data exchange under the Initial Joint Polar Satellite System agreement.[15] The French space agency CNES led development of the Infrared Atmospheric Sounding Interferometer (IASI), while the German Aerospace Center (DLR) contributed to the Global Ozone Monitoring Experiment-2 (GOME-2).[8] Due to the exceptional longevity of the first-generation satellites—exceeding their nominal 5-year design life—the EPS program was extended; MetOp-B and MetOp-C have far exceeded their nominal 5-year design lives, with MetOp-B and MetOp-C continuing to provide observations as of 2025 and expected to operate into the early 2030s, bridging to the MetOp Second Generation satellites.[16] In June 2014, EUMETSAT approved the follow-on MetOp Second Generation (MetOp-SG) program, with an initial budget of approximately €3.3 billion (as approved in 2014) for six satellites, now estimated at around €5.2 billion for the full program including operations, to ensure continuity from the late 2020s.[17][18] The program faced challenges, notably delays in the MetOp-C launch, originally planned for late 2016 but postponed to 2018 due to scheduling conflicts and preparation issues. Despite broader concerns with the Soyuz launch vehicle, MetOp-C lifted off successfully on November 7, 2018, completing the first-generation constellation.[19][20] The MetOp-SG program advanced with the successful launch of the first satellite, MetOp-SG A1, on 13 August 2025 from Europe's Spaceport in Kourou aboard an Ariane 6 rocket.[2]Heritage and Predecessors
The MetOp program traces its roots to the European Space Agency's (ESA) Meteosat geostationary satellite series, which began with the launch of Meteosat-1 in 1977 and provided continuous meteorological observations from equatorial orbits, establishing Europe's foundational capabilities in operational weather monitoring.[21] This geostationary heritage informed MetOp's emphasis on real-time data dissemination for numerical weather prediction, as managed by EUMETSAT, but highlighted the limitations of geostationary systems in covering high-latitude regions effectively.[22] A significant influence came from ESA's experimental Earth observation missions, particularly the European Remote-Sensing Satellites (ERS-1 and ERS-2), launched in 1991 and 1995, respectively, which operated until 2000 and demonstrated advanced radar technologies including scatterometry for wind measurements over oceans.[22] MetOp adopted key elements from ERS, such as the modular platform design that facilitated cost-effective, long-duration operations in polar orbits, and incorporated scatterometer heritage through instruments like ASCAT, evolving from ERS's active microwave capabilities.[21] Additionally, ERS's radar altimetry expertise influenced MetOp's approach to precise atmospheric profiling, though adapted for meteorological priorities.[23] Internationally, MetOp drew substantial heritage from the U.S. National Oceanic and Atmospheric Administration's (NOAA) TIROS-N and subsequent Polar-orbiting Operational Environmental Satellites (POES) series, initiated with TIROS-N in 1978, which introduced microwave sounding for cloud-penetrating observations and established polar-orbiting meteorology as a global standard.[24] This lineage provided shared instrument foundations, including the Advanced Very High Resolution Radiometer (AVHRR) for imaging and the High-resolution Infrared Radiation Sounder (HIRS) for atmospheric profiling, both carried on POES satellites and integrated into MetOp to ensure compatibility and continuity in data products.[25] The collaboration stemmed from the 1998 International Joint Polar Satellite System (IJPS) agreement between NOAA and EUMETSAT, building on decades of POES operational experience.[23] The transition to MetOp was driven by the need for a European polar-orbiting complement to geostationary systems like Meteosat, addressing coverage gaps at high latitudes where geostationary views are oblique or absent, and responding to NOAA's anticipated reduction in morning-orbit services in the early 1990s.[22] Originating from ESA's 1992 Polar-Orbit Earth Observation Mission (POEM) concept—intended as a post-ERS successor—MetOp was separated into a dedicated meteorological platform to fill this void, enabling dual-orbit coverage (morning and afternoon) for enhanced global forecasting accuracy.[21] These predecessors collectively shaped MetOp's design for sustained, interoperable operations, leveraging proven technologies to support long-term climate and weather monitoring.[24]First-Generation Satellites
Satellite Specifications
The first-generation MetOp satellites utilize a modular platform developed by a European consortium led by Airbus Defence and Space (formerly EADS Astrium), featuring a Service Module (SVM) for core functions and a Payload Module (PLM) for instrument accommodation, derived from established Airbus bus designs.[26] Thales Alenia Space contributed to key structural and integration elements of the platform.[8] The overall launch mass is 4,085 kg, including 316 kg of hydrazine fuel, with a dry mass of 3,769 kg; the SVM accounts for 1,380 kg, the PLM for 1,214 kg (excluding instruments), the solar array for 255 kg, and the payload suite for approximately 920 kg.[26] [27] In stowed configuration under the launcher fairing, the satellites measure 6.2 m in length by 3.4 m in width and height, expanding in orbit to 17.6 m across the solar array span, with overall dimensions of 17.6 m × 6.6 m × 5.0 m when fully deployed.[26] [21] The power subsystem relies on single-sided gallium arsenide solar arrays generating up to 3.89 kW at end-of-life (EOL), supplemented by five 40 Ah NiCd batteries for eclipse periods, supporting an average orbital power demand of 1.81 kW EOL across the platform and instruments.[8] Propulsion is provided by a blow-down hydrazine system with four pressurized tanks and two redundant branches, each equipped with eight 23.5 N thrusters for orbit maintenance, station-keeping, and momentum dumping.[8] [28] Attitude control employs three-axis stabilization via the SVM's Advanced Orbit Control System (AOCS), achieving a pointing accuracy of 0.3° to ensure precise instrument alignment for global observations.[8] Communications include an omnidirectional S-band system for telemetry, tracking, and command (TT&C) at downlink rates up to 4 kbit/s and uplink at 2 kbit/s, while payload data is transmitted via X-band at up to 3 Mbit/s for direct readout or stored and dumped at higher rates to EUMETSAT polar ground stations in Svalbard, Norway, and McMurdo, Antarctica.[8] [29] Redundancy is integrated throughout the design, including dual-string electronics for critical subsystems, redundant propulsion branches, and backup solar array sections, enabling mission durations exceeding the baseline 5 years.[8] [26] The platform is qualified for the low Earth orbit environment, withstanding vacuum levels down to 10^{-5} Pa and operational temperatures from -20°C to +50°C to maintain reliability during polar passes.[8]Launches and Status
The first-generation MetOp satellites were launched over a span of more than a decade to establish and maintain the EUMETSAT Polar System. MetOp-A, the inaugural satellite, was launched on 19 October 2006 from the Baikonur Cosmodrome in Kazakhstan aboard a Soyuz-2.1a/Fregat rocket. Following a successful launch and early orbit phase, it began providing initial operational data in December 2006, with full commissioning completed by May 2007. MetOp-A operated for over 15 years, far exceeding its designed five-year lifespan, before the decommissioning process began on 15 November 2021; it was fully retired by 30 November 2021 and subsequently de-orbited to a lower altitude for controlled re-entry.[30][31][2] MetOp-B followed as the second satellite in the series, launched on 17 September 2012, also from Baikonur using a Soyuz-2.1a/Fregat launch vehicle. It transitioned to full operational status in April 2013 after completing its commissioning phase, taking over primary responsibilities from MetOp-A. The satellite has continued to provide reliable data despite some instrument degradations over time, with its expected end-of-life projected around 2027 based on performance trends.[32][33][34] The third and final first-generation satellite, MetOp-C, was launched on 7 November 2018 from the Guiana Space Centre in French Guiana via a Soyuz-ST-B/Fregat launcher, marking a shift to the European launch site for improved accessibility. It achieved operational readiness in April 2019 and occupies a morning ascending node orbit to complement the constellation. MetOp-C is anticipated to remain active into the 2030s, supporting extended mission continuity.[2][33][31]| Satellite | Launch Date | Launch Site and Vehicle | Operational Start | Status as of November 2025 |
|---|---|---|---|---|
| MetOp-A | 19 October 2006 | Baikonur Cosmodrome, Soyuz-2.1a/Fregat | December 2006 (initial), May 2007 (full) | Decommissioned (November 2021) |
| MetOp-B | 17 September 2012 | Baikonur Cosmodrome, Soyuz-2.1a/Fregat | April 2013 | Operational (EOL ~2027) |
| MetOp-C | 7 November 2018 | Guiana Space Centre, Soyuz-ST-B/Fregat | April 2019 | Operational (EOL ~2030s) |