|  | Different spheres of the Earth system | |
Earth Explorers
The biggest environmental issue we currently face is global change, which encompasses not only climate change but also the large-scale impact that a growing global population and continued economic growth are having on the Earth and its environment. Earth Explorer satellites provide an important contribution to the global endeavour to further our understanding of the Earth system.
Earth Explorer missions form the science and research element of ESA's Living Planet Programme and focus on the atmosphere, biosphere, hydrosphere, cryosphere and the Earth's interior with the overall emphasis on learning more about the interactions between these components and the impact that human activity is having on natural Earth processes.
Earth Explorer missions are divided into two categories – Core and Opportunity. Core missions respond directly to specific areas of public concern and are selected through widespread consultation with the science community. Opportunity missions are smaller, low-cost satellites that are relatively quick to implement so that they are to address areas of immediate environmental concern. The user-driven approach is fundamental for both type of mission. The process of mission selection has given the Earth science community an efficient tool for advancing the understanding of the Earth system. The science questions addressed also form the basis for development of new applications of Earth observation.
To date, there have been three Core missions and three Opportunity missions selected for implementation.
Core missions:
GOCE
The Gravity field and steady-state Ocean Circulation Explorer (GOCE), the first Earth Explorer Core mission, was placed in orbit on 17 March 2009. GOCE will provide high spatial resolution gravity gradient data with which to improve global and regional models of the Earth's gravity field and geoid.
ADM-Aeolus
The prime aim of the Atmospheric Dynamics Mission is to demonstrate measurements of vertical wind profiles from space, using a high performance Doppler Wind Lidar based on direct-detection interferometric techniques. ADM-Aeolus is due for launch in 2011.
EarthCARE
Earth Clouds Aerosols and Radiation Explorer (EarthCARE) will improve the representation and understanding of the Earth's radiative balance in climate and numerical forecast models. EarthCARE is due for launch in 2013.
Opportunity missions:
SMOS
The Soil Moisture and Ocean Salinity (SMOS) mission, launched on 2 November 2009, will exploit an innovative instrument designed as a two-dimensional interferometer for acquiring brightness temperature observations at L-band (1.4 GHz) for the estimation of soil moisture and ocean salinity to further our understanding of the Earth's water cycle.
CryoSat-2
The CryoSat-2 satellite replaces CryoSat, which was lost as a result of launch failure in October 2005. Scheduled to be launched on 25 February 2010, CryoSat-2 will measure fluctuations in the thickness of ice on both land and sea to provide conclusive evidence as to whether there is indeed a trend towards diminishing ice cover, furthering our understanding of the relationship between ice and global climate. CryoSat-2 will carry an innovative SAR/Interferometric Radar Altimeter (SIRAL).
Swarm
The objective of this mission is to provide the best-ever survey of the geomagnetic field and its temporal evolution in order to gain new insights into the Earth system by improving our understanding of the Earth's interior and climate. Swarm is due for launch in 2011.
Future missions:
Following the Earth Explorer selection process, there are currently three candidate missions undergoing Feasibility Study. One of these missions will eventually be selected as ESA's seventh Earth Explorer mission:
BIOMASS – to take global measurements of forest biomass.
CoReH2O (Cold Regions Hydrology High-resolution Observatory – to make detailed observations of key snow, ice and water cycle characteristics.
PREMIER (PRocess Exploration through Measurements of Infrared and millimetre-wave Emitted Radiation) – to understand processes that link trace gases, radiation, chemistry and climate in the atmosphere.
Last update: 14 January 2010 | 
SMOS launch
Earth Observation Proposal Upload System (EOPUS) 
Earth Explorers 
