Sentinel-3 is an Earth observation heavy satellite

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used i ...

developed by the

European Space Agency The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...

as part of the

Copernicus Programme Copernicus is the Earth observation component of the European Union Space Programme, managed by the European Commission and implemented in partnership with the Member state of the European Union, EU member states, the European Space Agency (ES ...

. As of 2024, it consists of 2 satellites:

Sentinel-3A Sentinel-3A is a European Space Agency Earth observation satellite dedicated to oceanography which launched on 16 February 2016. It was built as a part of the Copernicus Programme, and is the first of four planned Sentinel-3 satellites. Its siste ...

and

Sentinel-3B Sentinel-3B is a European Space Agency Earth observation satellite dedicated to oceanography which launched on 25 April 2018. It was built as a part of the Copernicus Programme, and is the second (after Sentinel-3A, launched 16 February 2016) o ...

. After initial commissioning, each satellite was handed over to

EUMETSAT The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) is an intergovernmental organisation created through an international convention agreed by a current total of 30 European Member States. EUMETSAT's primary ...

for the routine operations phase of the mission. Two recurrent satellites, Sentinel-3C and Sentinel-3D, will follow in approximately 2025 and 2028 respectively to ensure continuity of the Sentinel-3 mission. Each Sentinel-3 satellite is designed to operate for seven years in a

sun-synchronous A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

low-Earth orbit. The satellites use multiple sensors to measure topography, temperature, marine ecosystems, water quality, pollution, and other features for ocean forecasting and environmental monitoring.

Overview

The Sentinel-3 satellites travel in a

orbit at an altitude of approximately , with an inclination of 98.6° and orbit cycle of approximately 100 minutes. The local time of

descending node An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined. A non-inclined orbit, which is contained in the reference plane, has no nodes. Planes of reference Common planes of referenc ...

is 10:00 a.m. and nominal duration is 7.5 years. A pair of Sentinel-3 satellites enables a short revisit time, allowing the earth to be imaged at least once every two days by the OLCI instrument, and at least once per day by the SLSTR instrument at the equator. This is achieved using both Sentinel-3A and Sentinel-3B satellites in conjunction. The satellite orbit provides a 27-day repeat for the topography package, with a 4-day sub-cycle.

Pre-launch

On 14 April 2008, the European Space Agency and

Thales Alenia Space Thales Alenia Space () is a joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (company), Leonardo (33%). The company is headquartered in Cannes, France. It provides space-based ...

signed a contract to build the first GMES Sentinel-3 in its

Cannes Mandelieu Space Center The Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located in both the towns of Cannes and Mandelieu in France. After a long history in aircraft manufacturing, starting in 1929, the center became incr ...

. Bruno Berruti led the team that was responsible for delivering the Copernicus Sentinel-3 satellites from the drawing board into orbit. The satellite platform was delivered to France for final integration in 2013. The communications systems were completed by Thales Alenia Space España in early 2014.

Launch

was subsequently launched on 16 February 2016 on a

Rokot Rokot ( meaning ''Rumble'' or ''Boom''), also transliterated Rockot, was a Soviet Union (later Russian) space launch vehicle that was capable of launching a payload of into a Earth orbit with 63° inclination. It was based on the UR-100N ( ...

vehicle from the

Plesetsk Cosmodrome Plesetsk Cosmodrome () is a Russian spaceport located in Mirny, Arkhangelsk Oblast, near the town of Plesetsk, from which it takes its name. Until 2025 and the commissioning of the Andøya Space, Andøya base in Norway, it was the only operati ...

, located near Arkhangelsk, Russia. This first launch was followed by the launch of

on 25 April 2018, also aboard a Rokot. Each satellite is designed to operate for 7 years.

Objectives

The Sentinel-3 mission's main objectives are to measure

sea-surface topography Ocean surface topography or sea surface topography, also called ocean dynamic topography, are highs and lows on the ocean surface, similar to the hills and valleys of Earth's land surface depicted on a topographic map. These variations are exp ...

, land- and sea-surface temperature, land- and ocean-surface colour with accuracy in support of ocean forecasting systems, and for environmental and climate monitoring. Sentinel-3 builds directly on the heritage pioneered by

ERS-2 European Remote Sensing satellite (ERS) was the European Space Agency's first Earth-observing satellite programme using a polar orbit. It consisted of two satellites, ERS-1 and ERS-2, with ERS-1 being launched in 1991. ERS-1 ERS-1 launched ...

and

Envisat Envisat ("Environmental Satellite") is a large Earth-observing satellite which has been inactive since 2012. It is still in orbit and considered space debris. Operated by the European Space Agency (ESA), it was the world's largest civilian Ear ...

satellites. Near-real time data will be provided for ocean forecasting, sea-ice charting, and

maritime safety Maritime safety as part of and overlapping with water safety is concerned with the protection of life ( search and rescue) and property Property is a system of rights that gives people legal control of valuable things, and also refers to th ...

services on the state of the ocean surface, including surface temperature,

marine ecosystem Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in Saline water, waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 7 ...

s, water quality, and pollution monitoring. Further objectives of the mission include: *Measure sea-surface topography, sea-surface height, and significant wave height *Measure

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

and land-surface temperature *Measure ocean and land-surface colour *Monitor sea and land ice

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

*Sea-water quality and

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

monitoring *Inland water monitoring, including rivers and lakes *Aiding

marine weather forecasting Marine weather forecasting is the process by which mariners and meteorological organizations attempt to forecast future weather conditions over the Earth's oceans. Mariners have had rules of thumb regarding the navigation around tropical cyclone ...

with acquired data *

Climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...

monitoring and

modelling A model is an informative representation of an object, person, or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin , . Models can be divided into ...

Land-use change Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: for ...

monitoring *Forest cover mapping *Fire detection *

Weather forecasting Weather forecasting or weather prediction is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather info ...

*Measuring Earth's thermal radiation for atmospheric applications

Instruments

Sentinel-3 makes use of multiple sensing instruments:

SLSTR

SLSTR (Sea and Land Surface Temperature Radiometer) determines global sea-surface temperatures to an accuracy of better than . It measures in nine spectral channels and two additional bands optimised for fire monitoring. The first six spectral bands cover the

visible and near-infrared The visible and near-infrared (VNIR) portion of the electromagnetic spectrum has wavelengths between approximately 400 and 1100 nanometers (nm). It combines the full visible spectrum with an adjacent portion of the infrared spectrum up to th ...

(VNIR) spectrum as well as the

short-wave infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

(SWIR) spectrum; VNIR for bands 1 to 3, and SWIR for bands 4 to 6. These 6 bands have a spatial resolution of , while bands 7 to 9 as well as the two additional bands have a spatial resolution of . For the SLSTR instrument on Sentinel-3, calibration on-board is one of the most important features for the thermal and infrared channels. This instrument has two

black body A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The radiation emitted by a black body in thermal equilibrium with its environment is ...

targets used for calibration, one at similar temperature to the optics (about ), and one at a higher temperature (), such that the temperature range corresponds to ocean surface temperatures measured by the instrument.

OLCI

OLCI (Ocean and Land Colour Instrument) is a medium-resolution imaging

spectrometer A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomeno ...

that uses five cameras to provide a wide field of view. The OLCI is an along-track or "push broom" scanner, meaning that the

sensor array A sensor array is a group of sensors, usually deployed in a certain geometry pattern, used for collecting and processing electromagnetic or acoustic signals. The advantage of using a sensor array over using a single sensor lies in the fact that an ...

is arranged perpendicular to the path of flight. This method essentially eliminates the scale distortion near the edge of an image that is common with across-track or "whisk broom" scanners. OLCI has 21 spectral bands with wavelengths ranging from the optical to the near-infrared. Bands vary in width from 400 nm to 1020 nm, and serve a variety of different purposes, including measuring

water vapour Water vapor, water vapour, or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Water vapor ...

absorption,

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...

levels, and

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

absorption. SLSTR and OLCI are optical instruments with an overlap of their swath path, allowing for new combined applications. Due to climate changing factors, inland coastal regions have become an increased area of concern, and from 2002 to 2012 the Medium Resolution Imaging Spectrometer (

MERIS MEdium Resolution Imaging Spectrometer (MERIS) was one of the main instruments on board the European Space Agency (ESA)'s Envisat platform. The sensor was in orbit from 2002 to 2012. ESA formally announced the end of Envisat's mission on 9 May 2012. ...

) provided quality observations for analysis. The OLCI improves upon the MERIS in that it was built with six additional spectral bands, higher-end

signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to noise power, often expressed in deci ...

(SNR), reduced solar glar, a maximum of 300 m spatial resolution, and increased ground coverage allowing it to sense

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

levels within inland coastal ecosystems. OLCI is currently the only sensor in space able to detect cyanobacteria.

SRAL

Sea-level variations from Sentinel-3A ESA359994

SRAL (

Synthetic Aperture Aperture synthesis or synthesis imaging is a type of interferometry that mixes signals from a collection of telescopes to produce images having the same angular resolution as an instrument the size of the entire collection. At each separation and ...

Radar Altimeter A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it t ...

) is the main topographic instrument to provide accurate topography measurements over sea ice, ice sheets, rivers, and lakes. It uses dual-frequency K_u and C band and is supported by a

microwave radiometer A microwave radiometer (MWR) is a radiometer that measures energy emitted at one millimeter-to-metre wavelengths (frequencies of 0.3–300 GHz) known as microwaves. Microwave radiometers are very sensitive receivers designed to measure thermally ...

(MWR) for atmospheric correction and a DORIS receiver for orbit positioning. This allows the instrument, which is based on legacy missions such as

CryoSat CryoSat is an European Space Agency, ESA programme to monitor variations in the extent and thickness of polar ice through use of a satellite in low Earth orbit. The information provided about the behaviour of coastal glaciers that drain thinning ic ...

and the

Jason Jason ( ; ) was an ancient Greek mythological hero and leader of the Argonauts, whose quest for the Golden Fleece is featured in Greek literature. He was the son of Aeson, the rightful king of Iolcos. He was married to the sorceress Med ...

missions, to provide a 300-meter resolution and a total range error of 3 cm. The instrument operates its pulse repetition frequency at 1.9 kHz (low-resolution mode - LRM, real aperture radar) and 17.8 kHz (synthetic aperture radar - SAR).

DORIS

DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) is a receiver for orbit positioning.

MWR

MWR (MicroWave Radiometer) measures water vapour, cloud water content, and the thermal radiation emitted by the Earth. The MWR sensor has a radiometric accuracy of .

LRR

LRR ( Laser retroreflector) accurately locates the satellite in orbit using a laser ranging system. When used in combination with SRAL, DORIS, MWR, they will acquire detailed topographic measurements of the ocean and in-land water.

GNSS

GNSS (

Global Navigation Satellite System A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are op ...

) provides precise orbit determination and can track multiple satellites simultaneously.

Satellite operation and data flow

Sentinel-3 is operated by the

European Space Operations Centre The European Space Operations Centre (ESOC) serves as the main mission control centre for the European Space Agency (ESA) and is located in Darmstadt, Germany. ESOC's primary function is the operation of uncrewed spacecraft on behalf of ESA and ...

(ESA) during the Commissioning Phase (E1) and

from the routine operations phase onwards. The in-orbit operations for Sentinel-3 are managed by EUMETSAT in

Darmstadt, Germany Darmstadt () is a city in the state of Hesse in Germany, located in the southern part of the Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it the fourth largest city in the state of Hesse aft ...

. This includes monitoring the health of the satellite and the instruments, and coordinates housekeeping

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', 'far off', an ...

and commands at the main flight control center in Darmstadt, Germany. EUMETSAT maintains a Back-Up Control Centre in Torrejon, Spain. In addition, the ESA operates an x-band core station in

Svalbard Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway be ...

, Norway. This station is responsible for receiving the data collected by Sentinel-3. The data is then analysed by the Sentinel Collaborative Ground Segment and compiled into the Copernicus Space Component (CSC). The CSC is an earth observation program run by the ESA with the objective of providing high quality continuous monitoring of the earth. EUMETSAT generates and disseminates the marine and near-real-time atmospheric data from its own facilities in Darmstadt.

Applications

Extreme temperatures in Eureka ESA22181121

The applications of Sentinel-3 are diverse. Using the collection of sensors on-board Sentinel-3 is able to detect ocean and land temperature and colour change. The Ocean and Land Color Instrument (OLCI) has a resolution with 21 distinct bands allowing global coverage in less than four days. This sensor can then be used to by researches to do water quality and land-monitoring research. The satellite also has the ability to monitor the temperature of the sea, land and ice through the Sea and Land Surface Temperature Radiometer (SLSTR). Sentinel-3 also has the ability to detect changes in sea-surface height and sea-ice using the

synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or 3D reconstruction, three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target regi ...

altimeter An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth under water. Ty ...

and the

, two of the most complex sensors on the satellite. The observations acquired by the mission will be used to in conjunction with other ocean-observing missions to contribute to the Global Ocean Observing System (GOOS) which aims to create a permanent system of ocean observation. *Ocean colour and land reflectance data *Sea, land, and ice surface temperature *Active fire and burnt area monitoring *Sea surface topography data

Gallery

File:Bering Sea ESA376705.jpg, Bering Sea File:Cyclone Debbie ESA375411.jpg,

Cyclone Debbie Severe Tropical Cyclone Debbie in 2017 was the strongest tropical cyclone to strike Queensland since Cyclone Marcia, Marcia in 2014–15 Australian region cyclone season, 2015, and was the costliest tropical cyclone in Australia since Cyclone ...

File:Kamchatka, Russia ESA374357.jpg, Kamchatka, Russia File:United Kingdom ESA361630.tiff, United Kingdom File:Hinnamnor 2022-09-01 0159Z.jpg,

Typhoon Hinnamnor Typhoon Hinnamnor, known in the Philippines as Super Typhoon Henry, was a very large and powerful tropical cyclone that impacted Japan, South Korea, Taiwan, the Philippines, and Russia in early September 2022. The eleventh named storm, fourth ty ...

off the coast of Taiwan File:Madagascar Sentinel-3.jpg, A view of

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

and the

Mozambique Channel The Mozambique Channel (, , ) is an arm of the Indian Ocean located between the Southeast African countries of Madagascar and Mozambique. The channel is about long and across at its narrowest point, and reaches a depth of about off the coa ...

File:Spain’s chilly blanket ESA22415247.jpeg, Snowfall from

Storm Filomena Storm Filomena was an extratropical cyclone in early January 2021 that was most notable for bringing unusually heavy snowfall to parts of Spain, with Madrid recording its heaviest snowfall in over a centur and with Portugal being hit less se ...

visible on the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

in January, 2021

Overview

Pre-launch

Launch

Objectives

Instruments

SLSTR

OLCI

SRAL

DORIS

MWR

LRR

GNSS

Satellite operation and data flow

Applications

Gallery

References

External links