Sentinel 3 is an Earth Observation satellite mission developed by the ESA as part of the Global Monitoring for Environment and Security GMES program. GMES is the European programme to establish a European capacity for Earth Observation designed to provide European policy makers and public authorities with accurate and timely information to better manage the environment, understand and mitigate the effects of climate change and ensure civil security.
Sentinel-3 is designed to ensure the long-term collection and operational delivery of high-quality measurements to GMES ocean, land, and atmospheric services, while contributing to the GMES, emergency and security services. Key Sentinel-3 measurement requirements, corresponding to identified user needs, have been derived from GMES users as follows:
- Sea surface topography (SSH), significant wave height (Hs) and surface wind speed derived over the global ocean to an equivalent accuracy and precision as that presently achieved by Envisat Radar Altimeter-2 (RA-2) (radar altimetry) but with enhanced surface topography measurements in the coastal zone, sea ice regions and over inland rivers, their tributaries and lakes.
- Sea surface temperature (SST) determined for oceanic and coastal waters globally to an equivalent accuracy and precision as that presently achieved by the Envisat Advanced Along Track Scanning Radiometer (AATSR) over the ocean (i.e. <0.3 K), at a spatial resolution of 1 km.
- Visible, and Short-Wave Infrared radiances for oceanic, inland and coastal waters at a spatial resolution of 0.3 km (simultaneously and co-registered with SST measurements), determined to an equivalent level of accuracy and precision as Envisat Medium Resolution Imaging Spectrometer with complete ocean coverage in 2-3 days.
- Visible and infrared radiances over global land-surfaces in 1-2 days, sea-ice and ice-sheets equivalent to those currently provided from ENVISAT MERIS, AATSR and Système Probatoire d'Observation de la Terre (SPOT) Vegetation.
The Sentinel-3 mission addresses these requirements by implementing and operating:
- A dual frequency, Synthetic Aperture Radar Altimeter (SRAL) (see radar altimetry)instrument supported by a dual frequency passive microwave radiometer (MWR) for wet-tropospheric correction, a Precise Orbit Determination package including a GPS receiver, a DORIS instrument and a laser retro-reflector.
- A highly sensitive Ocean and Land Colour Imager (OLCI) delivering multi-channel wide-swath optical measurements for ocean and land surfaces.
- A dual-view Sea and Land Surface Temperature Radiometer (SLSTR) delivering accurate surface ocean, land, and ice temperature.
- A collaborative ground segment providing management of the mission, management, development, production and access to core data products in an operational near real time delivery context.
The mission foresees a series of satellites, each having 7-year lifetime, over a 20-year period starting with the launch of Sentinel-3A late 2014 (as of October 2012) and of Sentinel-3B ~18 months later. During full operations two identical satellites will be maintained in the same orbit with a phase delay of 180°.
On the 14th of April 2008, The European Space Agency and Thales Alenia Space signed a €305 million contract to build the first GMES Sentinel-3.
 Mission characteristics
- Role: Earth Observation
- Launch date: 2014
- Launch mass: ~1250 kg
- 'Launcher' class: Vega or Rokot/Kourou
- Launch location: French Guiana
- Orbit: Sun-synchronous
- Altitude: 814.5 km
- Inclination: 98.65 °
- Local time of Ascending Node: 10:00
- Orbit cycle: ~100 minutes
- Nominal duration: 7.25 years
- Ocean and Land Colour Instrument (OLCI)
- Sea and Land Surface Temperature Instrument (SLSTR)
- Synthetic Aperture Radar Altimeter (SRAL)
- Microwave Radiometer (MWR)
- GNSS receiver
- Laser retroflector
- DORIS system
- Ocean colour and land reflectance data
- Sea, land and Ice surface temperature
- Active fire and burnt area monitoring
- Sea surface topography data
- C. Donlon, B. Berruti, A Buongiorno, M-H Ferreira, P. Femenias, J. Frerick, P. Goryl, U. Klein, H. Laur, C. Mavrocordatos, J. Nieke, H. Rebhan, B. Seitz, J. Stroede, and R. Sciarra, The Global Monitoring for Environment and Security (GMES) Sentinel-3 Mission, Remote Sensing of the Environment, 120,27-57, http://dx.doi.org/10.1016/j.rse.2011.07.024, 2012.
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