EARTH AND SPACE
Europe sets its sights on GMES
GMES(1) – Global Monitoring for Environment and Security – is one of the three pillars of European space policy. Devoted to Earth observation, it is the result of increased co-operation between the European Commission and the ESA and, over the coming decade, is destined to be the operational hub of the GEOSS ‘system of systems’.
"In 2020, every citizen or local official will be able to check the state of his personal environment, via the Internet, at global or village level.” It is in these terms that Josef Aschbacher, coordinator of the Earth Observation programmes at the ESA during recent years, defines the GMES ambitions.
|Mappemonde of ozone column heights (see colour scale) in the Southern Hemisphere, produced by researchers at the Deutsches Zentrum für Luft- und Raumfahrt (DLR - DE) using data gathered by the Dutch meteorological services from the ERS-2 (GOME) sensors.|
The starting signal for this essential component of the EU’s space and environmental policy was given back in 2000. Since then, this vast project has been acknowledged as one of the key priorities in meeting the EU’s environmental monitoring needs and in boosting its role on the world stage(2).
The commitment to this strategic development is also an indication of the Union’s political desire to have an autonomous observation capacity – in particular for its security objectives – and to make these available to the international community as well as to European users. “The idea at the basis of the GMES is the same as that which justifies the Galileo global system of satellite navigation. It is the independence of a Europe that must be able to count on its own global information sources,” explains Volker Liebig, who was appointed head of the European Space Agency’s (ESA) Earth Observation programmes on 1 October 2004.
Eye on a changing globe
At a founding seminar held in Lille by the French Presidency of the Union on the subject of ‘Space – Monitoring and protecting the environment’, former Research Commissioner Philippe Busquin set out the three major reasons that justified the decision for Europe to commit itself to this ambitious global objective.
|Testing the Envisat platform at the ESTEC (NL) site prior to launch.|
Firstly, to understand and control global change. "Satellite data are vital to the construction, validation and calibration of physical models of the terrestrial system,” he explained. “In particular, they permit progress in our essential understanding of the complex carbon cycle, which the European CarboEurope project aims to shed light on. Satellites must also help us to ensure that international agreements are respected, such as the UN agreement on global change, the Kyoto Protocol and the Convention on Biodiversity, to which the European Union is a party.”
Secondly, to study the various phenomena that exert pressure on the environment. These phenomena include variations in water resources at global level and ozone layer depletion. The latter is the subject of several European campaigns in northern Europe.
Finally, to prevent and take emergency action in the wake of natural and manmade disasters, such as the "forest fires that have caused such damage to Europe’s Mediterranean regions”.
The GMES did not come out of the blue. In addition to the traditional Meteostat geostationary satellites (with a fixed orbit over the Greenwich meridian and used by the Eumetstat organisation), the ESA developed and launched into polar orbit, at an altitude of around 800 km, its first ERS-1 environmental observation satellite back in 1991. Its twin, the ERS-2, was launched in 1995.
Each was equipped with a synthetic aperture radar, a radiometer and an altimeter radar. The duo worked in tandem for one year. Their orbits had been adjusted so that their instruments traced virtually the same line across the Earth’s surface, flying over the same regions at one day’s interval. The slight remaining difference in their path made it possible to create pairs of interferometric images that served as a basis for producing digital 3D maps and highlighting movements in the earth’s crust. ERS-1 was taken out of service in March 2000 after having helped acquire 1.5 million radar images; ERS-2 is continuing to produce data on the size of oceans and extent of the polar icecaps.
In March 2002, the ESA provided the ERS with a remarkable successor: the Envisat (Environment Satellite) observatory. Weighing eight tonnes, this civil remote detector is the largest ever produced. A multifunctional platform equipped with ten instruments using the full spectrum of the most advanced observation technologies, it is the most ambitious mission undertaken by the ESA in the field of automatic satellites.
The community of users of ERS and Envisat data gathered for a week from 6 to 10 September 2004 in Salzburg. This highly specialised seminar enabled participants to take stock of the situation and to compare opinions on the combined use of space sensors. It highlighted the usefulness of space observatories for analysing space phenomena, monitoring the composition of the atmosphere, observing movements of the earth’s surface, defining the extent of flooded areas, and tracking the spread of forest fires and oil slicks. The meeting also identified a panoply of experimental applications that are destined to assume an operational dimension in the framework of the GMES services.
Go skyward and multiply
The abundant crop of images and data harvested by Envisat – and to a lesser extent by the still operational ERS-2 – looks set to continue over the coming years. Nevertheless, their successors for the short and medium term have already been chosen and there will no longer be any question of launching bulky multisensor platforms. Within the next five years, Europe will begin to place into orbit constellations of lighter satellites – possibly on the same launcher. Having many small sensors dedicated to specific missions increases significantly the observation frequency of the areas covered, with varying spectrums and resolutions. Such an approach also makes it possible to work with less centralised terrestrial reception terminals and facilitates data processing and dissemination.
|View of the Richat structure, a circular geological formation 50 km in diameter in the deserts of Mauritania.|
About 30 satellites could soon be scrutinising the Earth. The growing number of observatories is testimony to the creativity and expertise of the scientists working at the various climatic and environmental centres and institutes – backed by engineers and European space sector companies – in developing the technologies that enable us to improve our knowledge of the factors that influence our planet.
The ESA is currently developing its Living Planet programme that will provide the preparatory transition between the Envisat/ERS era and future GMES systems. Two families of satellites are being developed in this framework: the Earth Explorers, which will be dedicated principally to scientific research, and Earth Watch, which will provide operational monitoring data on the weather, agriculture, forests, geology, oceans, urban and coastal areas, risk management, etc. Under the Earth Explorer banner, the ESA will soon be deploying new instruments for the continuous measurement and detailed analysis of the polar icecaps (EE-Cryosat -2005), the Earth’s gravity field and the ocean depths (EE-Goce - 2006), soil humidity and ocean salinity (EE-Smos - 2007), and atmospheric currents (EE-Aeolus -2007).
Many observation satellites will also be deployed within the Earth Watch family between 2005 and 2008/2010, some with a public service mission and others commercially, as well as dual use (civil and military) satellites, often in the form of constellations.
Under the auspices of Eumetsat, the first Meteosat Second Generation was put into orbit on 28 August 2002. Three others have been ordered and will be joining the current fleet by 2018. Furthermore, the first of a new family of three MetOp satellites is scheduled to be launched into polar orbit in 2005. A number of launches are planned in this area by Member States: TerraSAR (2006) and Rapideye (2007), German commercial satellites for geophysical services; Cosmoskymed (2006-2007), a constellation of radar satellites developed by Italy; Pléiades (2008-2009), two French satellites to carry on from the Spot missions; and Topsat, (2005), for multispectral imaging, developed by the United Kingdom.
A breath of fresh oxygen
All these European satellites – about 30 should be put into near orbit – will be part of the GMES jigsaw which is still at the definition stage. It is expected to be operational within a decade. Europe’s aim in pursuing this ambitious programme is clearly to acquire an increased Earth observation capacity.
|The Kiruna station (SE): receives data transmitted by the ERS-1 and ERS-2 satellites.|
Over a period of two and a half years, the preparatory work on implementing the GMES was carried out jointly by the European Commission and the ESA. This resulted in a framework agreement between the ESA and the European Commission’s Directorate-General for Research, signed on 25 November 2003, and that entered into force on 28 May 2004. Beginning in 2008, Europe will have to deploy new capacities to arrive at a top class and autonomous network providing global monitoring of the environment and security.
Although the programme’s objectives are easy to understand, what, specifically, does its deployment involve? “The first thing is not to duplicate what is already being done, but to fill the gaps in our information on the environment and security. These gaps were identified in the framework agreement,” explains Volker Liebig.
Firstly, the existing space observation capacities must be integrated. In the longer term, the development strategy adopted includes two space segments for which the ESA is responsible, Sentinel and Oxygen (or O2, acronym for Open and Operational). The first of these concerns an operational fleet of specialised satellites that will operate alongside the systems put into place five years ago, by the ESA as well as the Member States.
In the GMES framework, the objective – that can be realised by means of co-operative actions – is to deploy constellations of global environment observatories. These will serve the GEOSS strategy within the framework of a 10-year plan. Five Sentinel satellite sub-groups are currently being studied to provide an extended and multiform coverage that uses the gamut of observation technologies (see box).
At the same time, the ESA is studying the complex terrestrial infrastructure that is used to exploit the various observations. Liebig believes that Oxygen will make it possible to “coordinate, harmonise, and unify the terrestrial infrastructure in Europe for the purposes of observations from space”. In the GMES system, it must translate into operational capacities for the systems of the future and the information products that users are seeking.
In line with demand
"The Agency is too inclined to define the demand it must meet on the basis of its own criteria,” admits Jean-Jacques Dordain, Director-General of the ESA, who stresses the need for a rapprochement between the world of space and the needs of society. “It is important to establish a dialogue between the supplier of space systems, on the one hand, and the customers, on the other. This dialogue is necessary to see if the solution is technically and financially feasible. GMES must be the European motor for global co-operation between those who possess space programmes and those who need them, whether citizens of Europe or of the world.
To meet these requirements, priority is awarded to the interoperability between user tools and the resources of the ground segments established for the various missions. The specific observation data themes – the Service Elements – are currently being determined. The aim is to create synergies between the interested centres, laboratories and companies across the EU so as to define their needs. These should be covered by the wide-ranging applications that will be part of the GMES programme, especially in terms of customers and countries (see box).
The timetable for the GMES services proposed by the ESA’s Earth Observation Directorate is as follows:
Hervé Jeanjean, continental environment programme manager at France’s Centre National d’Etudes Spatiales (CNES), has no hesitation in speaking of a golden age of remote detection by satellite: “Technological advances over the past 20 years now make it possible to envisage putting into place operational systems combining progress in analytical methods and information system models.”
- implementation of the GMES system between 2005 and 2012
- European operational autonomy from 2013
- GMES contributing to GEOSS by 2015
As for the cost of all this, the GMES final report mentions €5 billion over a ten-year period, including €2.3 billion for the space segment and its ground infrastructure. The Union will fund two-thirds of the total investment and the ESA one-third.
|Slovenia: map of potential landslide slopes produced by the Research Centre at the Slovenian Academy of Sciences.|
(1) Global Earth Observation System of Systems
(2) In addition to the Galileo system of civil satellite navigation, the GMES space segment occupies a key position alongside programmes for space exploration and to close the ‘digital divide’.