Ground Segment

T he Global Monitoring of Environment andnSecurity (GMES) programme is based on alfleet of European Earth observation

satellites, built and operated by ESA, memberstates and commercial entities. GMES will alsooffer data from non-European satellites. Inorder to provide operational and sustainableuser services and to avoid unnecessaryduplication in technologies, the challenge is toharmonise the various approaches to theground segments of the different satellites andto involve the users. To begin this harmonisationprocess, a Ground Segment Coordination Bodywas created to adopt a common, coordinatedand cost-effective approach that responds tothe needs of Earth observation users.

IntroductionThe demand for Earth observation (EO)data has evolved dramatically in recentyears: the volume of requested data hasincreased by a factor of 10 over the last8 years, and more than 80% of the usersrequest data from more than onesatellite or satellite operator.

This, in turn, increases the challengefor satellite operators, space agenciesand providers of EO data to offer theaccess to the different data as coherently

Eugenia Forcada & Gunther KohlhammerDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

Catherine CasgrainCanadian Space Agency, Montreal, Canada

Yves LavergneEumetsat, Darmstadt, Germany

Alberto TuozziItalian Space Agency (ASI), Rome, Italy

Gunter SchreierGerman Aerospace Center (DLR),Oberpfaffenhofen, Germany

Maurice WinterholerFrench Space Agency (CNES), Toulouse, France

esa bulletin 129 - february 2007 19

Reaping the Rewards

Coordinating Europe’sEarth ObservationGround System

The torrents of data from a widerange of different Earth observationsatellites must be handled in aharmonised way for maximumbenefit. This image shows theeruption of Mt. Etna on Sicily25 November 2006, seen by theMERIS instrument aboard ESA’sEnvisat

Forcada 2/9/07 9:46 AM Page 18

Ground Segment

T he Global Monitoring of Environment andnSecurity (GMES) programme is based on alfleet of European Earth observation

satellites, built and operated by ESA, memberstates and commercial entities. GMES will alsooffer data from non-European satellites. Inorder to provide operational and sustainableuser services and to avoid unnecessaryduplication in technologies, the challenge is toharmonise the various approaches to theground segments of the different satellites andto involve the users. To begin this harmonisationprocess, a Ground Segment Coordination Bodywas created to adopt a common, coordinatedand cost-effective approach that responds tothe needs of Earth observation users.

IntroductionThe demand for Earth observation (EO)data has evolved dramatically in recentyears: the volume of requested data hasincreased by a factor of 10 over the last8 years, and more than 80% of the usersrequest data from more than onesatellite or satellite operator.

This, in turn, increases the challengefor satellite operators, space agenciesand providers of EO data to offer theaccess to the different data as coherently

Eugenia Forcada & Gunther KohlhammerDirectorate of Earth Observation Programmes,ESRIN, Frascati, Italy

Catherine CasgrainCanadian Space Agency, Montreal, Canada

Yves LavergneEumetsat, Darmstadt, Germany

Alberto TuozziItalian Space Agency (ASI), Rome, Italy

Gunter SchreierGerman Aerospace Center (DLR),Oberpfaffenhofen, Germany

Maurice WinterholerFrench Space Agency (CNES), Toulouse, France

esa bulletin 129 - february 2007 19

Reaping the Rewards

Coordinating Europe’sEarth ObservationGround System

The torrents of data from a widerange of different Earth observationsatellites must be handled in aharmonised way for maximumbenefit. This image shows theeruption of Mt. Etna on Sicily25 November 2006, seen by theMERIS instrument aboard ESA’sEnvisat

Forcada 2/9/07 9:46 AM Page 18

and easily as possible. It also demandsoptimisation in allocating the availablefinancial resources to handle anincreasing number of different EOmissions through closer cooperation indeveloping the ground segment, theoperations and exploiting the data.

A task force set up by ESA’s EarthObservation Programme Board (PB-EO)in 2003–2004 came up with a set ofrecommendations on how to deal withthese challenges. One was the creation ofa Ground Segment Coordination Body(GSCB), composed of member-stateagencies managing EO data groundsegments.

GSCB was established in June 2005and shares the expertise in thedevelopment and operation of payloadground segments of missions such as:

– Meteosat, MSG and MetOp byEumetsat;

– TerraSAR-X, Rapid Eye, TanDEM,EnMAP and third-party missionshandled by the German AerospaceCenter (DLR);

– Radarsat-1 and -2 by the CanadianSpace Agency (CSA);

– COSMO-Skymed by the Italian SpaceAgency (ASI);

– Spot, Topex-Jason and Pleiades by theFrench Space Agency (CNES);

– ERS-1 and -2, Envisat, Earth Explorermissions and third-party missions byESA.

The group coordinates and shares itsfindings with other coordination andstandardisation entities such as CEOS(Committee on Earth ObservationSatellites), OGC (Open GeospatialConsortium) and CCSDS (Consultative Committee for Space DataSystems), and it plans for regularconsultation with industry andcommercial missions.

European GMES Earth Observation MissionsThe first task of GSCB was tocoordinate the ground segment and datamanagement of the most importantEuropean and Canadian EO missionsduring the lifetime of GMES. These

Mapping and Analysis Programme).EnMAP covers the spectral range420–2450 nm with more than 200 bandsof 5–10 nm spacing. The 30 m pixelscover a swath of 30 km; off-nadirviewing enables 5-day repeat coverage.EnMAP will help the study of eco-systems and the monitoring of naturalresources.

Radarsat-1/2 (Canada)The Radarsat-2 follow-up to Radarsat-1,launched in 1995, is a collaborationbetween government (CSA) andindustry (MacDonald, Dettwiler andAssociates Ltd). It is designed to provideC-band SAR data similar to those fromRadarsat-1 for continuity. Significanttechnical improvements were made,including a 3 m high-resolution mode, afull range of signal polarisation modesto improve discrimination betweenvarious surface types, superior datastorage and more precise measurementsof satellite position and attitude.

Radarsat-2 will operate in a Sun-synchronous orbit identical to that ofRadarsat-1 but with an offset. It isplanned for launch around March/April2007.

Envisat (ESA)Envisat was launched on 1 March 2002and since then has operated with a 35-day repeat cycle, 30 minutes ahead ofERS-2. The instruments address fourmajor areas: radar imaging; opticalimaging over oceans, coastal zones and

existing and planned missions areoutlined below.

COSMO- SkyMed (Italy)COSMO-SkyMed is funded by ASI andthe Italian Ministry of Defence. Thesystem, now being built, consists of aconstellation of four low Earth orbitmid-sized satellites, each carrying amulti-mode high-resolution X-bandSynthetic Aperture Radar (SAR), and aglobal ground segment. Launch of thefirst is planned for 2007.

The primary mission is to provideservices for land monitoring, territorystrategic surveillance, management ofenvironmental resources, maritime andshoreline control and law enforcement,topography and scientific applications.

Pleiades (France)The Pleiades optical system will consistof two small satellites (1 tonne each)offering resolutions of 70 cm panchro-matic and 2.8 m multispectral with afield of view of 20 km, better than itsSpot predecessors. In addition, thesystem can acquire near-instantaneousstereoscopic doubles (or even triples) of20 x 300 km, and provide highlyaccurate pinpointing of the images(< 1 m with ground control points) foroptimal use of the data in geographicalinformation systems. The first launch isplanned for 2009.

TerraSAR-X (Germany)Based on their experience with SAR

land; observation of the atmosphere;altimetry.

About two-thirds of the data aretransmitted to the ground via ESA’sArtemis relay satellite, providing Europewith data acquisition for any locationworldwide. A total of 78 product types isgenerated, amounting to 250 GBytesper day. Most of these products areavailable on the Internet in near-realtime.

The Envisat data are used in manyfields of Earth science, includingatmospheric pollution, fire extent, sea-ice motion, ocean currents andvegetation change, as well as foroperational activities such as mappingland subsidence, monitoring oil slicksand watching for illegal fisheries.

GMES Sentinels (ESA)Drawing on the preliminary work of thedefinition studies (Phases-A/B1), thekey aspects of the individual Sentinelmissions are described below.

Sentinel-1Sentinel-1 will provide continuity ofERS and Envisat SAR data, but athigher ground resolution and data-take

per orbit. It will carry a SAR in aprecisely controlled dawn-dusk Sun-synchronous orbit, at about 700 kmaltitude with an exact repeat of 12 daysand a swath of about 240 km. The firstlaunch is planned for 2011.

Sentinel-2Sentinel-2 will provide improvedcontinuity for the Spot multispectraloptical data, carrying a push-broomimager operating in the visible/near-IRand shortwave IR in a Sun-synchronousorbit at about 800 km altitude. Theresolution in the visible and near-IRchannels will be 10 m. The swath widthof the multispectral imager will be about280 km, ensuring systematic coverage ofall land surfaces every 10 days. The firstlaunch is planned for 2011.

Sentinel-3Sentinel-3, with a first launch in 2012,will monitor oceans and land/ atmo-sphere at a global scale. It will carry, in aSun-synchronous orbit of around800 km altitude:

– a microwave altimeter, with a micro-wave radiometer for atmosphericcorrection and a satnav receiver forprecise orbit determination;

– a 15-channel super-spectral imager forocean/land colour observations;

– a visible/IR imaging dual-view radio-meter for sea/land surface tempera-ture observations.

The land imaging mission will providecontinuity for Spot’s Vegetation instru-

technology from various national(SIR-C, SRTM) and ESA missions(ERS, Envisat), DLR and Astriumsigned a public-private partnershipagreement in March 2002, under whichDLR is procuring from Astrium theinnovative TerraSAR-X satellite.

The 1023 kg satellite will deliverX-band SAR data in various modes.The Spot-Light mode will yield thefinest resolution data, with 1 m pixelsfor a 10 x 10 km image. The ScanSARmode will deliver 16 m resolution in a100 km-wide swath. A special ‘splitantenna’ mode will allow experimentalin-track interferometry, such as themapping of moving objects. The satellitewill fly in a 514 km-high dawn-duskorbit and is scheduled for launch inFebruary 2007 from Baikonur.

TanDEM-X (Germany)In 2003, DLR issued a call for proposalsfor a national follow-on to TerraSAR-X.One of the two accepted proposals isTanDEM-X, which consists of a near-identical satellite flying in a closetandem configuration with TerraSAR-Xby 2009. This will allow interferometricdigital elevation models to be generatedglobally to the highest precision(‘DTED-3’ quality, with 10 m footprintand 2 m vertical accuracy).

EnMAP (Germany)The second national German mission,to be launched around 2010, is thehyperspectral EnMAP (Environmental

Earth Observation

esa bulletin 129 - february 2007esa bulletin 129 - february 2007 www.esa.intwww.esa.int 2120

Ground Segment

A Sentinel-1 concept

A Sentinel-2 concept

The Radarsat-2 satelliteThe Pleiades satellite The TerraSAR-X satellite

The Envisat satellite

Forcada 2/9/07 9:46 AM Page 20

and easily as possible. It also demandsoptimisation in allocating the availablefinancial resources to handle anincreasing number of different EOmissions through closer cooperation indeveloping the ground segment, theoperations and exploiting the data.

A task force set up by ESA’s EarthObservation Programme Board (PB-EO)in 2003–2004 came up with a set ofrecommendations on how to deal withthese challenges. One was the creation ofa Ground Segment Coordination Body(GSCB), composed of member-stateagencies managing EO data groundsegments.

GSCB was established in June 2005and shares the expertise in thedevelopment and operation of payloadground segments of missions such as:

– Meteosat, MSG and MetOp byEumetsat;

– TerraSAR-X, Rapid Eye, TanDEM,EnMAP and third-party missionshandled by the German AerospaceCenter (DLR);

– Radarsat-1 and -2 by the CanadianSpace Agency (CSA);

– COSMO-Skymed by the Italian SpaceAgency (ASI);

– Spot, Topex-Jason and Pleiades by theFrench Space Agency (CNES);

– ERS-1 and -2, Envisat, Earth Explorermissions and third-party missions byESA.

The group coordinates and shares itsfindings with other coordination andstandardisation entities such as CEOS(Committee on Earth ObservationSatellites), OGC (Open GeospatialConsortium) and CCSDS (Consultative Committee for Space DataSystems), and it plans for regularconsultation with industry andcommercial missions.

European GMES Earth Observation MissionsThe first task of GSCB was tocoordinate the ground segment and datamanagement of the most importantEuropean and Canadian EO missionsduring the lifetime of GMES. These

Mapping and Analysis Programme).EnMAP covers the spectral range420–2450 nm with more than 200 bandsof 5–10 nm spacing. The 30 m pixelscover a swath of 30 km; off-nadirviewing enables 5-day repeat coverage.EnMAP will help the study of eco-systems and the monitoring of naturalresources.

Radarsat-1/2 (Canada)The Radarsat-2 follow-up to Radarsat-1,launched in 1995, is a collaborationbetween government (CSA) andindustry (MacDonald, Dettwiler andAssociates Ltd). It is designed to provideC-band SAR data similar to those fromRadarsat-1 for continuity. Significanttechnical improvements were made,including a 3 m high-resolution mode, afull range of signal polarisation modesto improve discrimination betweenvarious surface types, superior datastorage and more precise measurementsof satellite position and attitude.

Radarsat-2 will operate in a Sun-synchronous orbit identical to that ofRadarsat-1 but with an offset. It isplanned for launch around March/April2007.

Envisat (ESA)Envisat was launched on 1 March 2002and since then has operated with a 35-day repeat cycle, 30 minutes ahead ofERS-2. The instruments address fourmajor areas: radar imaging; opticalimaging over oceans, coastal zones and

existing and planned missions areoutlined below.

COSMO- SkyMed (Italy)COSMO-SkyMed is funded by ASI andthe Italian Ministry of Defence. Thesystem, now being built, consists of aconstellation of four low Earth orbitmid-sized satellites, each carrying amulti-mode high-resolution X-bandSynthetic Aperture Radar (SAR), and aglobal ground segment. Launch of thefirst is planned for 2007.

The primary mission is to provideservices for land monitoring, territorystrategic surveillance, management ofenvironmental resources, maritime andshoreline control and law enforcement,topography and scientific applications.

Pleiades (France)The Pleiades optical system will consistof two small satellites (1 tonne each)offering resolutions of 70 cm panchro-matic and 2.8 m multispectral with afield of view of 20 km, better than itsSpot predecessors. In addition, thesystem can acquire near-instantaneousstereoscopic doubles (or even triples) of20 x 300 km, and provide highlyaccurate pinpointing of the images(< 1 m with ground control points) foroptimal use of the data in geographicalinformation systems. The first launch isplanned for 2009.

TerraSAR-X (Germany)Based on their experience with SAR

land; observation of the atmosphere;altimetry.

About two-thirds of the data aretransmitted to the ground via ESA’sArtemis relay satellite, providing Europewith data acquisition for any locationworldwide. A total of 78 product types isgenerated, amounting to 250 GBytesper day. Most of these products areavailable on the Internet in near-realtime.

The Envisat data are used in manyfields of Earth science, includingatmospheric pollution, fire extent, sea-ice motion, ocean currents andvegetation change, as well as foroperational activities such as mappingland subsidence, monitoring oil slicksand watching for illegal fisheries.

GMES Sentinels (ESA)Drawing on the preliminary work of thedefinition studies (Phases-A/B1), thekey aspects of the individual Sentinelmissions are described below.

Sentinel-1Sentinel-1 will provide continuity ofERS and Envisat SAR data, but athigher ground resolution and data-take

per orbit. It will carry a SAR in aprecisely controlled dawn-dusk Sun-synchronous orbit, at about 700 kmaltitude with an exact repeat of 12 daysand a swath of about 240 km. The firstlaunch is planned for 2011.

Sentinel-2Sentinel-2 will provide improvedcontinuity for the Spot multispectraloptical data, carrying a push-broomimager operating in the visible/near-IRand shortwave IR in a Sun-synchronousorbit at about 800 km altitude. Theresolution in the visible and near-IRchannels will be 10 m. The swath widthof the multispectral imager will be about280 km, ensuring systematic coverage ofall land surfaces every 10 days. The firstlaunch is planned for 2011.

Sentinel-3Sentinel-3, with a first launch in 2012,will monitor oceans and land/ atmo-sphere at a global scale. It will carry, in aSun-synchronous orbit of around800 km altitude:

– a microwave altimeter, with a micro-wave radiometer for atmosphericcorrection and a satnav receiver forprecise orbit determination;

– a 15-channel super-spectral imager forocean/land colour observations;

– a visible/IR imaging dual-view radio-meter for sea/land surface tempera-ture observations.

The land imaging mission will providecontinuity for Spot’s Vegetation instru-

technology from various national(SIR-C, SRTM) and ESA missions(ERS, Envisat), DLR and Astriumsigned a public-private partnershipagreement in March 2002, under whichDLR is procuring from Astrium theinnovative TerraSAR-X satellite.

The 1023 kg satellite will deliverX-band SAR data in various modes.The Spot-Light mode will yield thefinest resolution data, with 1 m pixelsfor a 10 x 10 km image. The ScanSARmode will deliver 16 m resolution in a100 km-wide swath. A special ‘splitantenna’ mode will allow experimentalin-track interferometry, such as themapping of moving objects. The satellitewill fly in a 514 km-high dawn-duskorbit and is scheduled for launch inFebruary 2007 from Baikonur.

TanDEM-X (Germany)In 2003, DLR issued a call for proposalsfor a national follow-on to TerraSAR-X.One of the two accepted proposals isTanDEM-X, which consists of a near-identical satellite flying in a closetandem configuration with TerraSAR-Xby 2009. This will allow interferometricdigital elevation models to be generatedglobally to the highest precision(‘DTED-3’ quality, with 10 m footprintand 2 m vertical accuracy).

EnMAP (Germany)The second national German mission,to be launched around 2010, is thehyperspectral EnMAP (Environmental

Earth Observation

esa bulletin 129 - february 2007esa bulletin 129 - february 2007 www.esa.intwww.esa.int 2120

Ground Segment

A Sentinel-1 concept

A Sentinel-2 concept

The Radarsat-2 satelliteThe Pleiades satellite The TerraSAR-X satellite

The Envisat satellite

Forcada 2/9/07 9:46 AM Page 20

ment, providing global coverage every4 days.

All Sentinels will fly in a two-satelliteconstellation to satisfy the coveragerequirements. All have design lifetimesof 7 years and, depending on their mass,are compatible either with the Soyuz(Sentinel-1: 2.5 tonnes) or the Vegalaunchers (Sentinel-2: 800 kg; Sentinel-3:1.3 tonnes).

Eumetsat Missions Meteosat First GenerationThe first generation of Meteosatgeostationary satellites has providedimages of the full Earth disc and datafor weather forecasts in a continuousand reliable stream for a quarter of acentury. The first was launched in 1977,with the last (Meteosat-7) following in1997 and still operational. Thesesatellites provide data 24 hours a dayfrom the three spectral channels (visible,IR, water vapour) of the main instru-ment every 30 minutes.

GSCB Work PlanBased on an initial 3-year plan definedat the end of 2005, GSCB began to workon the more critical domains for whichharmonisation at the European levelwould bring cost savings in the groundsegments and a discernible improvementin access to the EO data for users andservice providers.

The first (and main) project, theHeterogeneous Mission Accessibility(HMA) study, aims at the jointdefinition and adoption of inter-operability standards required toguarantee seamless and harmonisedaccess to heterogeneous EO datasets.

The initial step is to define standardsfor the discovery, cataloguing, ordering,accessing and delivery of EO data. Todo this, the GSCB is relying on theexperience of its members, whilefollowing international standards andcoordination with the EuropeanCommission’s INSPIRE programme.The first standardisation version throughthe Open Geospatial Consortium (OGC)and the European Committee forStandardisation (CEN) is targeted for 2007, with initial implementa-tion in 2009. Standardisation throughthe European Cooperation on SpaceStandardisation (ECSS) will follow.

The following steps of the project aredevoted to defining the harmonisedformat of EO data products and their quality certification and reporting.The first milestone for the data andquality harmonisation definition is2008.

The second project is the definition ofthe Payload Ground Segment referencearchitecture by identifying the differentbuilding blocks and interfaces, andexploiting the experience of the differentground segment operators. The adoptionof a reference EO ground architecturefor a simple, user-friendly, cost-efficientand inter-operable infrastructure willeventually be recommended, to:

– ease the implementation and integra-tion of new missions and EO data;

– reduce competitiveness in groundsegment development by industry;

Meteosat Second GenerationThe Meteosat Second Generation (MSG)is a significantly improved follow-onsystem. It consists of four geostationarymeteorological satellites, along withtheir ground infrastructure, that willoperate consecutively until 2018. MSGhas brought major improvements inresponse to user requirements andserves the needs of Nowcasting andNumerical Weather Prediction, inaddition to providing important data forclimate monitoring and research. Thekey instrument is the SpinningEnhanced Visible and InfraRed Imager(SEVIRI) radiometer, which deliversdaylight images of weather patternswith a resolution of 3 km. TheGeostationary Earth Radiation Budget(GERB) instrument measures theEarth’s radiation balance.

Eumetsat Polar SystemThe Eumetsat Polar System (EPS) isEurope’s first polar-orbiting operationalmeteorological satellite system. It is theEuropean contribution to the InitialJoint Polar-Orbiting OperationalSatellite System (IJPS) with the USNational Oceanic & AtmosphericAdministration (NOAA). The primeobjective is to provide continuous, long-term datasets for operational meteoro-logy, environmental forecasting andglobal climate monitoring.

EPS consists of a series of threeMetOp satellites, together with theirground system, with an operational lifeof at least 14 years. The first was

– serve the European EO data usercommunity in a harmonised way;

– provide a unified European technicalstandard towards GEOSS.

The third project is the definition andadoption of a common strategy for thelong-term preservation of EO data. Thestrategy will define the technical andmanagerial approach and providerecommendations for data access, securityand archive operations, maintenance andevolution, including data reprocessingand data integrity. The activity willcapitalise on policies already in force forpreserving digital data archives (at ESA,national space agencies, Eumetsat) andwill consider European Union initiativeslike the CASPAR project. The firststrategy proposal is planned for 2007.

Other areas of common interest are:

– the sharing of telecommunicationsnetworking infrastructure, bothground and satellite. The conceptrelies on the cost-benefit advantagesof procuring a common highercapacity network infrastructure,aggregating the needs from differentEO operators, rather than proceedingwith independent procurements;

– the optimisation of security require-ments for the future benefit of dualEuropean missions;

– the identification and sharing of toolsfor the description, test data genera-

tion and manipulation of EO productsand ground system interfaces.

GSCB is not a new standardisationbody. Its purpose is to identify andpromote the use of a common set ofstandards to perform the aboveactivities. In doing so, it liaises with thevarious existing standardisation bodiesor initiatives, such as OGC, GEO andINSPIRE.

AchievementsThe major achievement of GSCB is theHeterogeneous Mission Accessibilityproject, started in mid-2005 as part ofthe GMES Preparatory activities, to:

– consolidate the interoperability scen-arios and the related requirements;

– define the EO Data Access IntegrationLayer (DAIL) architecture;

– define and prototype the interoperableprotocol for cataloguing, ordering,mission planning and datadistribution;

– define the approach for user andsecurity management;

– address the interoperability require-ments arising from, for example, dataquality and formats, data policy andService Level Agreements.

HMA is focused on defining, and laterimplementing, the interoperabilityconcept across the ground segment ofthe missions contributing to the GMES

launched in October 2006. MetOp isflying in a Sun-synchronous orbit at analtitude of about 840 km, carrying apayload of 11 instruments that includesa new generation of operationalinstruments developed by Eumetsat,ESA and CNES, in addition to coreinstruments already flown on NOAAsatellites. Global data from new NOAAsatellites hosting a subset of MetOpinstruments will also be received andprocessed by the EPS ground segment.

GSCB in GMES and GEOSSThe GMES programme is based on afleet of European satellites built andoperated by ESA, ESA member statesand commercial entities. It will alsoprovide access to data from non-European satellites. GMES will there-fore rely on existing, planned and newdedicated space and in situ observationcapabilities to provide services to users.This open approach involves a complexscenario of data-providers, operatorsand system developers.

GSCB is intended to respond to thisneed for harmonised and coordinatedground-segment services at the Euro-pean level, in particular for providingEO data to the GMES services.

The results from GSCB will be fed intothe work plan of the Group on EarthObservation (GEO) and will contribute tosimilar activities under way beyondEurope, in an effort to built existingsystems and initiatives into a single system,the ‘Global Earth Observation System ofSystems’ (GEOSS), within 10 years.

Earth Observation

esa bulletin 129 - february 2007esa bulletin 129 - february 2007 www.esa.intwww.esa.int 2322

Ground Segment

A Sentinel-3 concept

The MSG satellite The MetOp satellite

Functional view of the HMA DAIL interactions with EO missions

Forcada 2/9/07 9:47 AM Page 22

ment, providing global coverage every4 days.

All Sentinels will fly in a two-satelliteconstellation to satisfy the coveragerequirements. All have design lifetimesof 7 years and, depending on their mass,are compatible either with the Soyuz(Sentinel-1: 2.5 tonnes) or the Vegalaunchers (Sentinel-2: 800 kg; Sentinel-3:1.3 tonnes).

Eumetsat Missions Meteosat First GenerationThe first generation of Meteosatgeostationary satellites has providedimages of the full Earth disc and datafor weather forecasts in a continuousand reliable stream for a quarter of acentury. The first was launched in 1977,with the last (Meteosat-7) following in1997 and still operational. Thesesatellites provide data 24 hours a dayfrom the three spectral channels (visible,IR, water vapour) of the main instru-ment every 30 minutes.

GSCB Work PlanBased on an initial 3-year plan definedat the end of 2005, GSCB began to workon the more critical domains for whichharmonisation at the European levelwould bring cost savings in the groundsegments and a discernible improvementin access to the EO data for users andservice providers.

The first (and main) project, theHeterogeneous Mission Accessibility(HMA) study, aims at the jointdefinition and adoption of inter-operability standards required toguarantee seamless and harmonisedaccess to heterogeneous EO datasets.

The initial step is to define standardsfor the discovery, cataloguing, ordering,accessing and delivery of EO data. Todo this, the GSCB is relying on theexperience of its members, whilefollowing international standards andcoordination with the EuropeanCommission’s INSPIRE programme.The first standardisation version throughthe Open Geospatial Consortium (OGC)and the European Committee forStandardisation (CEN) is targeted for 2007, with initial implementa-tion in 2009. Standardisation throughthe European Cooperation on SpaceStandardisation (ECSS) will follow.

The following steps of the project aredevoted to defining the harmonisedformat of EO data products and their quality certification and reporting.The first milestone for the data andquality harmonisation definition is2008.

The second project is the definition ofthe Payload Ground Segment referencearchitecture by identifying the differentbuilding blocks and interfaces, andexploiting the experience of the differentground segment operators. The adoptionof a reference EO ground architecturefor a simple, user-friendly, cost-efficientand inter-operable infrastructure willeventually be recommended, to:

– ease the implementation and integra-tion of new missions and EO data;

– reduce competitiveness in groundsegment development by industry;

Meteosat Second GenerationThe Meteosat Second Generation (MSG)is a significantly improved follow-onsystem. It consists of four geostationarymeteorological satellites, along withtheir ground infrastructure, that willoperate consecutively until 2018. MSGhas brought major improvements inresponse to user requirements andserves the needs of Nowcasting andNumerical Weather Prediction, inaddition to providing important data forclimate monitoring and research. Thekey instrument is the SpinningEnhanced Visible and InfraRed Imager(SEVIRI) radiometer, which deliversdaylight images of weather patternswith a resolution of 3 km. TheGeostationary Earth Radiation Budget(GERB) instrument measures theEarth’s radiation balance.

Eumetsat Polar SystemThe Eumetsat Polar System (EPS) isEurope’s first polar-orbiting operationalmeteorological satellite system. It is theEuropean contribution to the InitialJoint Polar-Orbiting OperationalSatellite System (IJPS) with the USNational Oceanic & AtmosphericAdministration (NOAA). The primeobjective is to provide continuous, long-term datasets for operational meteoro-logy, environmental forecasting andglobal climate monitoring.

EPS consists of a series of threeMetOp satellites, together with theirground system, with an operational lifeof at least 14 years. The first was

– serve the European EO data usercommunity in a harmonised way;

– provide a unified European technicalstandard towards GEOSS.

The third project is the definition andadoption of a common strategy for thelong-term preservation of EO data. Thestrategy will define the technical andmanagerial approach and providerecommendations for data access, securityand archive operations, maintenance andevolution, including data reprocessingand data integrity. The activity willcapitalise on policies already in force forpreserving digital data archives (at ESA,national space agencies, Eumetsat) andwill consider European Union initiativeslike the CASPAR project. The firststrategy proposal is planned for 2007.

Other areas of common interest are:

– the sharing of telecommunicationsnetworking infrastructure, bothground and satellite. The conceptrelies on the cost-benefit advantagesof procuring a common highercapacity network infrastructure,aggregating the needs from differentEO operators, rather than proceedingwith independent procurements;

– the optimisation of security require-ments for the future benefit of dualEuropean missions;

– the identification and sharing of toolsfor the description, test data genera-

tion and manipulation of EO productsand ground system interfaces.

GSCB is not a new standardisationbody. Its purpose is to identify andpromote the use of a common set ofstandards to perform the aboveactivities. In doing so, it liaises with thevarious existing standardisation bodiesor initiatives, such as OGC, GEO andINSPIRE.

AchievementsThe major achievement of GSCB is theHeterogeneous Mission Accessibilityproject, started in mid-2005 as part ofthe GMES Preparatory activities, to:

– consolidate the interoperability scen-arios and the related requirements;

– define the EO Data Access IntegrationLayer (DAIL) architecture;

– define and prototype the interoperableprotocol for cataloguing, ordering,mission planning and datadistribution;

– define the approach for user andsecurity management;

– address the interoperability require-ments arising from, for example, dataquality and formats, data policy andService Level Agreements.

HMA is focused on defining, and laterimplementing, the interoperabilityconcept across the ground segment ofthe missions contributing to the GMES

launched in October 2006. MetOp isflying in a Sun-synchronous orbit at analtitude of about 840 km, carrying apayload of 11 instruments that includesa new generation of operationalinstruments developed by Eumetsat,ESA and CNES, in addition to coreinstruments already flown on NOAAsatellites. Global data from new NOAAsatellites hosting a subset of MetOpinstruments will also be received andprocessed by the EPS ground segment.

GSCB in GMES and GEOSSThe GMES programme is based on afleet of European satellites built andoperated by ESA, ESA member statesand commercial entities. It will alsoprovide access to data from non-European satellites. GMES will there-fore rely on existing, planned and newdedicated space and in situ observationcapabilities to provide services to users.This open approach involves a complexscenario of data-providers, operatorsand system developers.

GSCB is intended to respond to thisneed for harmonised and coordinatedground-segment services at the Euro-pean level, in particular for providingEO data to the GMES services.

The results from GSCB will be fed intothe work plan of the Group on EarthObservation (GEO) and will contribute tosimilar activities under way beyondEurope, in an effort to built existingsystems and initiatives into a single system,the ‘Global Earth Observation System ofSystems’ (GEOSS), within 10 years.

Earth Observation

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Ground Segment

A Sentinel-3 concept

The MSG satellite The MetOp satellite

Functional view of the HMA DAIL interactions with EO missions

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initial phase. It provides a harmonisedand standardised access to ESA andthird-party mission data through theDAIL, which is a set of standardfunctions and interfaces. The concreteimplementation of DAIL will take intoaccount the requirements of specificmissions and the constraints of nationalfacilities.

In the initial phase, HMA gatheredthe experience of the agencies and EOdata ground segment operators bycollecting the detailed descriptions of allthe data access functionalities used inthe existing operational ground systems.The output is a set of specifications fordata discovery, cataloguing, orderingand programming services across arange of satellites.

These results were validated by theSystem Requirements Review in April2006.

In parallel, the detailed work on theinterface specifications derived from thescenarios was performed and submittedto the OGC, an international standardsorganisation that is leading thedevelopment of standards for geospatialand location-based services, andreviewed in close cooperation with the

INSPIRE initiative headed by theEuropean Commission. Several stand-ardisation workshops have beenorganised for discovery and catalogueservices to exploit the synergies amongthe EO datasets (targeted in the HMA)and the geospatial information(addressed by INSPIRE).

In September 2006, the DAIL archi-tecture was assessed and reviewed by allthe project partners and externaladvisors from the Food and AgriculturalOrganisation of the United Nations,INSPIRE and GEO.

Additional contracts will be in place inearly 2007 to implement DAIL and theinterfaces in the ground segments ofparticipating missions. The implement-ation phase will include an HMAtestbed to allow testing and evolution ofstandards proposed to OGC, and thestandards compliance test of any entityimplementing them.

ConclusionsIn response to the increasing need forEarth observation data to monitor thestate of our environment and supportpolicy decisions and investments,Europe has introduced the GMES

programme. Driven by the needs ofusers for highly sophisticated geo-information products, GMES will alsominimise the effort required for cross-use of the data from these systems.

GSCB was created to harmonise thedevelopment of the different groundinfrastructures and to ensure maximumdata availability for a wide variety of users.Although GSCB is not a standardisationbody, this coordinated approach has madea significant contribution towards thedefinition of interoperability and inter-accessibility standards.

The Body has to cope with the challengeof different national programmes and ofbringing together systems already inoperation with others still in planning.Various GSCB initiatives are beingorganised to foster the exchange ofinformation among mission-developersin Europe and Canada, the mostimportant being the HMA study.

A GSCB workshop in 2007 will bringtogether key players in the groundsegment industry and governments.Updates on the initiatives and studiesunder way will be presented and advicefrom participants will be sought on howthe GSCB can do better. e

Earth Observation

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initial phase. It provides a harmonisedand standardised access to ESA andthird-party mission data through theDAIL, which is a set of standardfunctions and interfaces. The concreteimplementation of DAIL will take intoaccount the requirements of specificmissions and the constraints of nationalfacilities.

In the initial phase, HMA gatheredthe experience of the agencies and EOdata ground segment operators bycollecting the detailed descriptions of allthe data access functionalities used inthe existing operational ground systems.The output is a set of specifications fordata discovery, cataloguing, orderingand programming services across arange of satellites.

These results were validated by theSystem Requirements Review in April2006.

In parallel, the detailed work on theinterface specifications derived from thescenarios was performed and submittedto the OGC, an international standardsorganisation that is leading thedevelopment of standards for geospatialand location-based services, andreviewed in close cooperation with the

INSPIRE initiative headed by theEuropean Commission. Several stand-ardisation workshops have beenorganised for discovery and catalogueservices to exploit the synergies amongthe EO datasets (targeted in the HMA)and the geospatial information(addressed by INSPIRE).

In September 2006, the DAIL archi-tecture was assessed and reviewed by allthe project partners and externaladvisors from the Food and AgriculturalOrganisation of the United Nations,INSPIRE and GEO.

Additional contracts will be in place inearly 2007 to implement DAIL and theinterfaces in the ground segments ofparticipating missions. The implement-ation phase will include an HMAtestbed to allow testing and evolution ofstandards proposed to OGC, and thestandards compliance test of any entityimplementing them.

ConclusionsIn response to the increasing need forEarth observation data to monitor thestate of our environment and supportpolicy decisions and investments,Europe has introduced the GMES

programme. Driven by the needs ofusers for highly sophisticated geo-information products, GMES will alsominimise the effort required for cross-use of the data from these systems.

GSCB was created to harmonise thedevelopment of the different groundinfrastructures and to ensure maximumdata availability for a wide variety of users.Although GSCB is not a standardisationbody, this coordinated approach has madea significant contribution towards thedefinition of interoperability and inter-accessibility standards.

The Body has to cope with the challengeof different national programmes and ofbringing together systems already inoperation with others still in planning.Various GSCB initiatives are beingorganised to foster the exchange ofinformation among mission-developersin Europe and Canada, the mostimportant being the HMA study.

A GSCB workshop in 2007 will bringtogether key players in the groundsegment industry and governments.Updates on the initiatives and studiesunder way will be presented and advicefrom participants will be sought on howthe GSCB can do better. e

Earth Observation

esa bulletin 129 - february 2007 www.esa.int24

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