Earth Explorers

Six explorers in the service of the planet

The Earth Explorers programme is ESA’s new initiative in the field of Earth observation satellites. Each of the six satellites focuses on a specific aspect of our biosphere.

Six explorers in the service of the planet
©ESA ©ESA

The European Space Agency (ESA) has changed its Earth observation strategy. Rather than concentrating all its resources on producing a single satellite with an impressive array of equipment for a variety of applications, as was the case with Envisat, it is now concentrating on satellites designed for more limited missions.

“More modest missions, more specialised – but also faster to implement,” explains Jérôme Benveniste of the Earth observation department at ESRIN (ESA –Italy). The Earth Explorers are concentrating on our planet’s atmosphere, biosphere, hydrosphere, cryosphere (ice cover) and of course the “hidden face” of the Earth’s interior. The aim is to learn more about the way these different “spheres” interact and the impact of our human activities.

Two types of satellite are orbiting under this programme. On the one hand, satellites that carry out “core” missions and that are interested in a very specific field of research are of great scientific interest and pursue the space agency’s long-term aims. Then there are those used for what are known as “opportunity” missions. These are smaller in scope but also fully managed by the ESA and can be launched in response to environmental issues of immediate concern on which the scientific community would like to obtain data quickly.

Lined up for launch

Of the six satellite missions currently being prepared, three will be carrying our core missions (GOCE, ADM-Aeolus and Earthcare) while the other three will be used for opportunity missions (SMOS, CryoSat-2 and Swarm).

The GOCE (Gravity field and steady-state Ocean Circulation Explorer) mission, scheduled for 2008, will be looking at the Earth’s gravitational field. Its data will be used to refine models in this field, improving our knowledge of the planet’s interior and geoid.

The SMOS satellite (Soil Moisture and Ocean Salinity) will be investigating the Earth’s water cycle. Scheduled for launch in 2008, SMOS will be taking large-scale measurements of soil moisture making it possible, for example, to avoid a loss of agricultural production due to drought by increasing irrigation. It will also be looking at changes in ocean salinity. The sphere of study for Cryosat-2 will be the cryosphere. The thickness of ice cover on both land and sea – thus including the vast ice sheets that cover Antarctica and Greenland – will be the focus of this satellite due to be launched in 2009. ADM-Aeolus (Atmospheric Dynamics Mission) will be analysing wind profiles of the atmo sphere and is scheduled for launch in 2009. Swarm will study the magnetic field and any changes over time. Three satellites will be launched as part of this mission that is due to start up in 2010. Finally, the Earthcare (Earth Clouds Aerosols and Radiation Explorer) mission, carried out in partnership with Japan, will seek to improve our knowledge of the Earth’s radiation balance (greenhouse effect, importance of aerosols, dust in the atmosphere, etc.), providing the means to improve our digital weather forecasting models. Scheduled launch: 2013.


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Next missions

The Earth Explorers programme does not end with the missions described above, as ESA has issued the scientific community with a new call for projects. This attracted 24 proposals and feasibility studies are currently being carried out on six of them.

These are Biomass (forest biomass), Traq (long-term transport of air pollutants), Premier (link between trace gases, radiation and chemistry in the atmosphere), Flex (study of photosynthesis by measuring fluorescence), A-Scope (global carbon cycle) and finally CoReH2O (water cycles in the snow and ice phases). The first of this new wave of satellites could be in space by 2010.


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