Galileo and GMES: Europe's Symbols of Independence in Space

bridges vol. 10, June 29 / Feature Articles
by Norbert Frischauf & Alexander Soucek

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Europe: 30 years in Space
In 1975 the European Space Agency (ESA) was inaugurated. ESA started small, with only a few countries, but within its three decades of existence it has succeeded in federating 17 European countries, including such heavyweights as France, Germany, Italy, and the United Kingdom. Even though ESA resembles roughly one-fifth of NASA in terms of annual budget (approximately €3 billion versus the $16.2 billion of NASA), the European agency has managed to consequently grow in importance to make a strong number two in the ranking of international space agencies, even though it focuses only on pure civilian space programs. Well, almost - even ESA cannot ignore the fact that today's world has become a bit more unpredictable, making it necessary to rely on one's own resources to proactively maintain safety and security for one's citizens. As such, ESA - in cooperation with the European Commission - has set up two programs to maintain and improve its technological-strategic portfolio within the space domain: Galileo and GMES.


GPS, GLONASS, and Galileo: Global Navigation Satellite Systems
Were it not for the US, no one would now be able to experience the benefits of readily available navigation at all places and at all times on a personal basis. Although the strategic value of precise navigational data on every possible place on Earth was clear from the very beginnings of human society and already acknowledged by the Roman Plutarch (46?-120 AD), who stated: "Navigare necesse est, vivere non est necesse!" it took humanity 2000 years to come up with a real global navigation system - simply because it requires a space element.

The working principle of the system is fairly easy as it makes use of only two physical factors: the constant speed of light and the fact that we can measure time differences relatively precisely. Combining these two things leads to a satellite-based system, where a satellite emits a time-stamped signal, the personal receiver combines it with its own time reference, and measures its distance to the satellite by calculating the time difference with the signal's speed (the speed of light). If one combines the signals of four satellites, the receiver can calculate latitude, longitude, and elevation as well.

Of course, things are not that easy. All this requires high precision atomic clocks, extensive orbital calculations and operations of the satellites, error corrections, and a highly sophisticated data transmission protocol to calculate one's position with a satisfying accuracy. The requirements are such that, for example, the "better" one of the two atomic clocks in the Galileo satellites features a maximum stability error of 1 ns per day. Such a clock will show a drift of only 1 second in 300,000 years!

Bearing this in mind, it is impressive that in 1973(!), the US military had already launched the first Global Navigation Satellite System (GNSS) with the name Global Positioning System (GPS). From the beginning, the GPS was designed to serve its primary customer - the US Armed Forces. Use of the signal by private entities was not explicitly encouraged but at least it wasn't prohibited. At this early time, there was of course no need to push the private use of GPS: not only were navigation-related applications perceived as pure science fiction, but also devices like PCs, the World Wide Web, mobile phones, and three-liter cars1 .

But by the end of the 90s, science fiction had turned into reality, when satellite-based navigation began to make an increasing appearance in the civilian sector. Navigation systems today are state-of-the-art in the airplanes of various airlines, are used in all sorts of ships, and more and more in cars and mobile phones. Japan is currently leading the commercial pack in terms of civilian applications: nearly every car has a GPS receiver installed and within the last three years location-based services have seen a real boom with Japanese telecomm operators.

Even though Europe and the United States do not feature such a developed navigation market as Japan, one can easily assume that in 10 or 20 years every European will use satellite navigation data, simply because it's convenient and saves a lot of time. OK, fine, but then why do we need Galileo, since we already have GPS providing navigational data free of charge?

Galileo: GNSS becomes European and civilian
Let's face it: GPS is an excellent GNSS that has set THE world-wide standard. But there is one major flaw: It is under military control. Being operated by the US Department of Defense, there is always the risk that in times of crisis, GPS will be degraded and/or switched off over specific regions if deemed necessary. This is, of course, the sole right of the US government, as it has invested ca. $6.3 billion between 1973 and 2002 (excluding military equipment and launch costs) and devotes an annual budget of approximately $750 million to keep the system operational. The money is spent to maintain and control a fleet of 24 satellites, which circle the Earth at an inclination of 55° once every 12 hours at an altitude of 20,200 km. This constellation allows users to estimate their position with an accuracy of 15 m, after the "selective availability" - an artificial degradation of the navigation signal, leading to an accuracy limitation of ca. 100 m - had been switched off in May 2000 by a directive of President Bill Clinton.

Still the word "availability" hangs like a sword of Damocles over GPS. Besides the fact that usage of GPS can be temporarily denied (some sort of "political availability"), there is also a physical limit to availability of the GPS signals. Twenty-four GPS satellites sounds like a whole lot, but when one takes into account that the accuracy increases with the number of satellites, that a typical airport runway is "only" 45 m wide, and that this system needs to cover the whole surface of the Earth, one can see that physical availability has its limits as well.

Bearing in mind that systems like GPS are becoming more and more important, the European decision to build Galileo as an independent, better-performing system under exclusive civilian control was quite logical. In 2003 the final decision was made, when ESA and the European Commission agreed on building Galileo in a Private Public Partnership (PPP) with European industry. Current estimates foresee an investment of €4.0 billion (including launches), of which €1.5 billion is designated for development and €2.5 billion is allocated for deployment. The operational costs in the utilization phase are estimated at €220 million per year. While the development phase is entirely funded by public entities (ESA and EU), the deployment phase is to be financed on a 70:30 share basis, with the private sector taking care of the 70 percent. Although €4 billion seems high at first glance, the costs of Galileo are not that extraordinary when one compared it with an infrastructure project such as building a highway. On the Galileo WWW-site of the EU, the costs of building 150 km of highway are estimated at €3.2 billion - if one looks at Germany with its dense Autobahn system, one can estimate how much money has been and is continuously being invested into infrastructure projects in Europe.

Once finished, the Galileo system will comprise 30 satellites (27 operational and 3 spares), circling the Earth in three distinct orbital planes with 9+1 satellites each, at an inclination of 56° and an altitude of 23616 km. Because of the larger number of satellites and more advanced technology (atomic clocks, dual frequencies, etc.), Galileo aims to provide a better availability and accuracy than GPS and will even offer 24/7 service under all but the most extreme circumstances. One search-and-rescue and four navigation services are part of the "Galileo package":

  • Open Service (OS): Combines open signals, free of charge, interoperable with GPS. Position and timing performances competitive with other GNSS systems (especially GPS IIF/III).
  • Safety of Life Service (SoL): Improves OS performances by providing timely warnings to the user when system integrity is hampered. A service guarantee is envisaged.
  • Commercial Service (CS): Provides access to two additional signals, to allow for a higher data rate throughput and to enable users to improve accuracy. A service guarantee is envisaged. This service also provides a limited broadcasting capacity for messages from service centers to users (in the order of 500 bits per second).
  • Public Regulated Service (PRS): Provides position and timing to specific users requiring a high continuity of service (also during times of crisis), with controlled access. Two PRS navigation signals with encrypted ranging codes and data will be available.
  • Search and Rescue Service (SAR): Will broadcast globally the alert messages received from distress emitting beacons. It will contribute to enhancing the performance of the international COSPAS-SARSAT SAR system.


This bundle of four navigation services and one service to support Search and Rescue operations has been identified to cover the widest range of users' needs, including professional users, scientists, mass-market users, safety of life, and public regulated domains. To give an impression of the types of specifications Galileo will feature, I will list the requirements for the Safety of Life Service as used by an aircraft approaching an airfield:

  • Coverage: Global
  • Horizontal accuracy (95%): 4 m - alarm limit: 12 m
  • Vertical accuracy (95%): 8 m - alarm limit: 20 m
  • Time to alarm: 6 s
  • Service availability: 99% - 99.9%
  • Certification/Liability: Yes

Even a non-expert might believe me when I say that this is quite demanding, especially when bearing in mind that the availability is above 99 percent! But Galileo has not only been kicked-off to supercede GPS, its objective is to lead to a paradigm shift that will make GNSS an integral (and mostly unnoticed) part of all our daily lives, in the same way as it happened with the telecomm satellites some years ago.

Military Interests -> Galileo <- Commercial Interests
As I stated in the introduction, Galileo not only serves commercial or scientific interests, but will also be used to support government-related activities. A dedicated service - the PRS - will provide position and timing signals to specific users requiring a high continuity of service (also during times of crisis), with controlled access. Two PRS navigation signals with encrypted ranging codes and data will be available to specific public entities like police, ambulance, coast guard, fire fighters, etc., as well as to the military.

Still, the major difference from GPS holds true, as Galileo - although offering the PRS - will remain a civilian controlled system, set up to provide its service on a 24/7 basis. The economic prospects remain the major driver of the system. Currently the worldwide market for GPS user equipment, applications, and services creates revenues of more than $10 billion per year, with the overall trend increasing. To put this in perspective: The GPS market is 50 percent bigger than the potato chip market! It should be no surprise that the economic forecasts for Galileo are bright as well. The Galileo Joint Undertaking, which is in charge of Galileo at the current stage, assumes the overall projected revenues will reach €8.5 billion over the PPP concession period of 20 years. During the same period, the incurred costs are expected to add up to ca. €7 billion - all in all a very positive balance.

Galileo: the way ahead
It remains to be seen if Galileo will be as successful as envisaged, as the greatest strength of Galileo compared to GPS is also its biggest weakness: its civilian, multilateral character. While GPS has only one stakeholder - the US government - Galileo is steered by a suite of organizations such as ESA, EU, GJU, and European industry. Even more, Europe has invited and succeeded in federating in other countries into the Galileo project, most notably China, India, Israel, Ukraine, Morocco, and South Korea. Further talks are in preparation and we will see how many stakeholders will finally form the Galileo family, once the system is operational after 2010.

The first major step in getting Galileo up and running was already achieved when GIOVE-A (Galileo In-Orbit Validation Element), the first of the two Galileo test satellites, was launched on December 28, 2005, by a Russian-European rocket (a Sojuz Fregat). For now it is the only satellite, but GIOVE-B is supposed to follow in autumn 2006. The first four "real" Galileo satellites are to be launched in 2008. Immediately afterwards the others will follow, so that in 2010 thirty European GNSS spacecrafts will provide a set of navigation and timing signals for all sorts of users on a global 24/7 availability, strictly under civilian control.

Looking back: Earth and Space - the case for GMES
After forty years of venturing into space, of exploring strange worlds and building human outposts in orbit, maybe the most intriguing and important asset of space flight is the backward glance: the discovery of planet Earth. It is with astonishment and curiosity that we learn to understand the complexity of this "blue system," its elements and interactions, past, present, and possible developments. Biosphere, atmosphere, cryosphere, hydrosphere, lithosphere - Earth observation is a "spherical" experience in three dimensions. It has turned our times into another age of discovery, and it has enabled science to deepen and expand the understanding of Earth in new, often surprising, dimensions.

At the current stage, Earth observation is in the process of maturation - it is constantly evolving from a purely science- or security-driven sector towards something often and ominously described as "operational." In other words, the space community is discovering a new dimension to one of its own means. This process, of course, is not the result of waking up one sunny morning and saying "Eureka!"; it's rather the sum of steps on a long way paved by increasingly better space-based observation systems, growing and increasingly interconnected ground systems, enhanced data and products, the development of exploitation strategies, strategic partnerships, and more. In fact, Earth observation has been used for many years for operational or quasi-operational purposes. Paralleling this, Earth observation underwent a process of popularization, namely in the field of high-resolution optical imagery. Google Earth and its recent success are both example and driver for such a process. Globalization has led to the need for global presence, global views, and global strategies. What better symbol could we take than an Earth observation satellite circling Earth within 90 minutes, virtually2 overlooking any point on the planet?

The inherently strategic factor of Earth observation is nothing new. It was the birth for this field of space activities, and the extension of aerial reconnaissance both in altitude and technology. "Spy satellites" are a common concept from the time of the space race. In fact, they still do exist, enhanced and advanced like their civilian brothers - the notion of "observing," however, has gained a completely new dimension.

Earth Observation as Space Application
Earth observation is one of the three components of what we can call the "magic triangle of space applications": navigation, communication, and observation. The United Nations' Outer Space Treaty of 1967, creating an international legal framework for the activities of humankind in space, mentions in its opening article:

The exploration and use of outer space, including the moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development, and shall be the province of all mankind.

Outer space, including the moon and other celestial bodies, shall be free for exploration and use by all States without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.

Exploration and use: We use outer space to communicate (without even thinking any more that our TV programs or phone calls travel up and down between the Earth's surface and geostationary "relay stations" at a distance of 36,000 kilometers), we happily accept the assistance of GPS and, soon, Galileo satellites, as described above. We are used to getting daily weather information or looking at "satellite images" in the newspaper. All these are based on the fact that we use the advantages of outer space, rising significantly above the Earth in order to capture and cover large parts of the planet in a short time using very advanced technology. Let us have a look at a true giant in space to help us understand the dimensions of modern Earth observation.

Envisat (Environmental Satellite) is the self-explanatory name of the biggest European Earth observation satellite ever launched into space. Brought into a sun-synchronous orbit at an altitude of 800 km on March 1, 2002, Envisat produces an unbelievable data flow of 250 Gigabytes per day, out of which currently 78 different products are generated around the clock. Envisat weighs 8140 kg and carries not less than ten instruments aboard - radiometers, spectrometers, an advanced synthetic aperture radar, and others - making it the Earth observation flagship of the European Space Agency. Envisat continues the heritage of ESA's Earth observation missions, namely ERS-1 (launched in 1991) and ERS-2 (launched in 1995 and still (!) operational). Its data are used for various purposes: first and foremost by scientists for manifold scientific projects in all disciplines, but also for commercial purposes and applications. A kaleidoscope of stories has accumulated:

  • measurement of a global sea level rise of three millimeters per year and a sea surface temperature increase of ~0.1 degree Celsius since 1992 ,
  • the worldwide monitoring of air pollution with evidence of fast-growing air pollution over rapidly developing areas since 1995,
  • the daily monitoring of sea ice motion and observation of Antarctic ice shelf collapse,
  • the quantification of global chlorophyll concentration (an index of the oceanic phytoplankton biomass),
  • the identification of blind tectonic faults,
  • land subsidence monitoring,
  • ship track or oil pollution detection,
  • surveillance of illegal fishery, and many other areas.

Compared to an exploration spacecraft around Mars - aside from the fascination and deeply human dimension of space exploration - the register of Envisat reads like an ever-changing, multi-faceted adventure story.

"Tomorrow mostly serene, in the south partially cloudy, temperatures around 20 degrees, low probability of thunderstorms." It couldn't be more usual and familiar, whether radio or TV, a daily ritual preparing for tomorrow. Data provided by Meteosat. Have a nice evening. In 1977, ESA launched the first Meteosat satellite. Placed over the equator at 0º longitude, it was equipped with an instrument looking at the electromagnetic spectrum in three channels (visible, infrared and water vapor region) around the clock - like its six successors. In 1986, the European Organization for the Exploitation of Meteorological Satellites was founded; since then, the ESA-built Meteosats (now in their second generation) have been handed over for operation to ESA's sister agency, which has established a successful network of meteorological data provision, services, and related applications.

These are but two examples from many dozens of Earth-observing satellites around the planet - every single one with a specific mission to generate data for one or more specific fields of Earth sciences, operational sciences, or applications. But the portfolio is much larger indeed: ESA is running the "Living Planet Program," aimed at "maintaining Europe at the leading edge of sciences." At the same time it increases the use of Earth observation in the formulation, implementation, and monitoring of public policies, as well as in the provision of public services, and tries to foster the development of commercial services using Earth observation. It is an ambitious undertaking that has led so far to the preparation of six "Earth Explorer" satellites: CryoSat5 , the ice mission; GOCE, the gravity mission; SMOS, the soil moisture and ocean salinity mission; ADM-Aeolus, the wind mission; SWARM, the magnetic field mission; and EarthCare, the cloud and aerosol mission. These highly sophisticated, yet small and very focused, missions will be launched in coming years.

Not only ESA and Eumetsat have made contributions in Earth observation. On the European level, other agencies deserve to be mentioned as well, most of all the French SPOT series of very successful Earth observation satellites. Globally, the United States of America, Russia, as well as a dozen other countries have entered the stage of Earth observation. All together, for the most varied reasons, these take a close look back at our planet, hourly, daily, continuously.

Behind the instruments
The way Earth observation works is simply described, yet impossible to convey in a few lines. Not because of the principles, but because of the varieties of observation methods. In short, everything is about taking pictures but with different instruments, and often not in the visible part of the spectrum. The most obvious method is optical imagery, whether pan-chromatic ("black and white," allowing for higher resolution) or multi-spectral ("in color", using/combining different channels). This observation mode relies, for obvious reasons, on good weather and correct (that is, useful) illumination conditions. Very high-resolution instruments currently provide for a ground resolution of 60 cm in the civil sector; military platforms achieve significantly better results. A close relative is infrared imagery, sensing "the Earth's temperature"; infrared sensors can be used for various purposes, e.g., hotspot or fire detection. So called active sensors operate with radiation emitted by the satellite itself, being reflected by the Earth, re-collected, and measured by the satellite. RADAR and LIDAR are the most prominent representatives. With Radar, features can also be detected at night or through clouds; advanced methods like the Synthetic Aperture Radar (SAR) allow for higher ground resolution. The use of microwaves reveals new, important features of the surface observed: its geometric composition (e.g., flat oil slicks versus rough surrounding sea) or its "volume" (chemical composition or status, e.g., moisture content). Interferometry is a technique that can generate relief images of the Earth's surface, opening a wide range of applications. But Earth observation has even more to offer: Atmosphere composition can be measured by analyzing starlight spectra after the light has passed through the atmosphere's layers; stereo imagery reveals geological information or is used for measuring ice motion. Spectrometers are used for a wide variety of applications, e.g., stratospheric chemistry, climatology, etc. Many other instruments are flown on board Earth observation satellites to cover as much of the scientific and application spectrum as possible.

GMES: A European awakening
Looking back at Earth reveals every possible insight into natural or human-originated activities; it creates data. Data provide information, and information is power. For some of the same reasons that make Europe feel more "comfortable" with an independent, space-based navigation system, it became interested in the possibility of a concerted, global, reliable, advanced, and multi-faceted Earth observation system, establishing, developing, and maintaining something we can call information independence. "Independence" reflects outwards as well as inwards: Despite the inherently strategic and security-impacting character of such a system, its rationale should not be limited to verification or surveillance - a simple global surveillance system (maybe not even in an environmental sense?) would certainly not have needed the enormous efforts currently spent on the national and institutional level of Earth observation in Europe. These efforts have a name, perhaps the "un-sexiest acronym" in Earth observation, but a name as a program: GMES, Global Monitoring for Environment and Security.

It started in Baveno, Italy. Back in 1998, in the small town at Lago Maggiore, the idea of GMES was formulated for the first time. From there, the road was long and difficult, until both the European Commission (EC) as well as ESA officially decided to make GMES the second largest "test balloon" of their increasingly beneficial and fruitful cooperation in the field of space. One catch phrase to cover it all: GMES - European independence in critical data sources for environmental monitoring and security.

What are the content and the status of GMES? The system itself could unofficially, but appropriately, be summarized as the "operative European network of Earth observation resources." Hence, GMES is not - as often described - limited to space-based Earth observation. Rather, as makes sense for a comprehensive approach, space is just one of many complementary parts, namely the in situ Earth observation and the data integration and management part. GMES is no gigantic science archive either. It follows a clearly operational approach: the development and fostering of Earth observation applications at the service of European policies and citizens. GMES' Practicability is in line with the overall European space policy approach and is reflected in sentences like the following: "Europe needs an extended space policy, driven by demand, able to exploit the special benefits space technologies can deliver in support of the Union's policies and objectives: faster economic growth, job creation and industrial competitiveness, enlargement and cohesion, sustainable development and security and defence."

Last but not least, GMES is no pure ESA program, nor does it consist solely of "GMES satellites," i.e., made up exclusively of satellites built for the purpose of establishing the system. Instead, GMES is a system with various components: ESA satellites, Eumetsat satellites, European national or multi-national satellites, and - depending on various technical, scientific, and political decisions - even non-European satellites. Such a complex array of literally dozens of instruments and sensors with hundreds of data types, products, and application fields, requires an extremely well-defined operational and governance frame. This is currently being discussed among the main players of GMES: the European Commission representing the European Union, ESA, and Eumetsat as classical inter-governmental organizations with both mandate and experience in the field of Earth observation, and the Member States of all three entities. Questions like the exact financial contributions and related administrative, logistic, and political questions are in the advanced stages of being finalized.

GMES therefore represents, as Europe's second flagship project, the underlying tripartite rationale of the European space policy: strategic influence, scientific progress, and economic growth7 . GMES is in itself a feedback loop: science and technology for policy needs, policy needs as push for science and technology.

Once operational - defined as delivering the first services under a concerted and well-defined European frame and starting in 2008 - GMES will make progressively comprehensive use of Earth observation for the formulation, implementation, and surveillance of European Union policies; the fields of applications are larger than thought at first glance. Earth observation data literally cover a broad spectrum: agricultural policies, environmental policies, security policies, urban development, disaster and natural hazards relief, land, coast, and sea information, water management, and many more. In order to provide for a rapid, effective, and prioritized approach, taking into account the most urgent data needs in today's European policy execution, the EC has, in cooperation with ESA, defined three application areas of priority - the so called Fast Track Services. They comprise "Land Management" (food security, agriculture, resource management, biodiversity, urban planning, etc.), "Marine Core Services" (ocean monitoring, coastal indicator services, sea ice monitoring, etc.) and "Emergency Management" (geo-hazard risk management, humanitarian aid, alert services, etc.). Two more "Fast Tracks" are waiting in the pipeline: atmospheric chemistry and security. ESA is already managing so called GMES Service Elements, which - operated by industrial consortia - make use of today's Earth observation portfolio for testing and consolidating thirteen different application areas involving more than 320 operational users - an important preparation for the GMES Fast Track Services to come.

A study by Price Waterhouse Cooper has recently estimated the total social benefit of an operational, pan-European system of global Earth observation to bring a gross benefit of several hundred billion Euros over the entire span of the program.

A "good, old European" fleet in the making
Today, GMES is already far beyond studies and estimations. The new family of core satellites being built for GMES, the Sentinels, are on track to realization. In contrast with the doggerel abbreviation, "GMES," the "Sentinels" carry a clear name - and they have an even clearer mission: to watch over our planet, to safeguard the treasure chest of human life and existence. The Sentinels will consist of five different instrument groups, realized largely in parallel and brought into space on a staggered schedule: The family of Sentinel-1 will continue ESA's heritage of SAR imaging, providing for day and night, all-weather applications, including a continued success story of interferometry. Estimated ground resolution will lie in the range of 10 to 30 meters, providing for ocean, ice, and land applications of a great variety. The first Sentinel-1 satellite will be launched in summer 2011 (according to the current plan). The family of Sentinel-2 will cover super-spectral imaging from space, carrying instruments with 10 to 30 meters resolution largely for land-mapping purposes. The Sentinel-3 family will fulfill many purposes at the same time: 100-1000 m wide-swath thermal infrared instruments for sea surface and land temperature measurements, 100-1000 m wide-swath multi-spectral instruments for ocean color and global land monitoring, and radar altimeters for ocean current measurements. Last but not least, the Sentinel-4 and Sentinel-5 families are intended to provide atmospheric composition monitoring from two different positions in space, a low Earth orbit position (Sentinel-4) and a geostationary position (Sentinel-5). Besides other tasks, these missions will give new insights into climate change issues. They will be launched after 2015.

The GMES "watchdogs" will be realized in the coming decade by ESA; the operation of the satellites will be organized according to an international administrative scheme still in the making. The "final fantasy" (to use a popular phrase of science fiction literature) is clear, fascinating, and important: a multi-national, multi-institutional fleet of Earth-observing satellites, covering the entire range of data needed, feeding a complete user chain from data providers via service providers to actual operational users - the Union, the States, the regions, the public institutions, the single end-user - for a better understanding of the planet, a better, truth-based view of environmental problems and security issues, and a better (because more efficient) support for the large portfolio of European policies. With Galileo and GMES operating, space will have finally arrived for the individual citizen. Complemented by an ambitious and mind-opening space exploration program, these initiatives will have the potential of maintaining Europe as one of the leading space players of tomorrow.

National - European - Global: today and tomorrow
The Sentinels are, as explained above, complemented by many other missions and instruments. Various national missions are providing additional elements of the system. Only with common, widespread yet harmonized resources on the ground, in the air, and from space, will the idea of GMES be successful. This is even more important as GMES will not be limited to the European perspective: It is the European contribution to GEOSS, the Global Earth Observation System of Systems (call it a global "Super-GMES") which, once functional and operational, will pave the way to a truly globalized world of Earth observation for the benefit of all: the Earth, its spheres, its citizens - and the future of them all.

About the authors:

Norbert Frischauf, is a high energy physicist by education and and works as high-technology consultant for Booz Allen Hamilton in Europe.

Alexander Soucek works at the European Space Agency on international data policy and legal aspects of earth observation.

Views expressed in this article are those of the authors and may not reflect those of the ESA or Booz Allen Hamilton.

1) So called in Europe as they use a maximum 3 liters of fuel over a distance of 100 kilometers.
2) Of course the myth of an Earth observation satellite being present at any time over any place is a complete misunderstanding. Due to orbital physics, any given satellite is enormously restricted in terms of "footprint" (the projected path of the satellite on the Earth's surface) and "repeat cycle" (the time between flying over a specific point on the surface again). For those and other reasons, we cannot speak of "global, permanent and continuous observation" of the Earth today. Let's therefore just take it as a symbol.
3) Treaty for Treaty on principles governing the activities of states in the exploration and use of outer space, including the moon and other celestial bodies; opened for signature at Moscow, London, and Washington on January 27, 1967; Article 1, para. 1 and 2
4) Measurements by ERS and Envisat
5) CryoSat was the first Earth Explorer to be launched; unfortunately, due to the failure of the launch vehicle, CryoSat was lost on October 8, 2005, over the Arctic Ocean. After a decision by ESA Member States, a recovery mission named CryoSat-2, is currently being built, ready to launch in 2009.
6) Space: a new frontier for an expanding Union, EC White Paper on European Space Policy, page 4
7) See also: (accessed 01 June 2006){/access}