The biggest environmental issue we face is global change, which not only encompasses climate change, but also the large-scale impact that a growing global population and continued economic growth is having on the environment.
The natural processes that shape our planet’s systems are dynamic, complex and highly interdependent. Understanding the intricacies of the Earth system and how human activity is affecting the natural world is a huge scientific challenge.
It is crucial that we continue to learn more about our planet if we are to better predict the effects of change and respond to issues that humankind will face in the coming decades.
Responding to these needs, ESA’s Earth Explorer missions provide an important contribution to the global endeavour to further our understanding of our planet.
The Explorers are research missions designed to address key scientific challenges identified by the Earth science community while demonstrating breakthrough technology in observing techniques. This user-driven 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, the family of Earth Explorers include the following missions:
GOCE: ESA's gravity mission
Launched on 17 March 2009 and ended on 11 November 2013, the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission provided the data to accurately determine global and regional models of Earth's gravity and geoid. This is advancing research in areas of ocean circulation, physics of Earth's interior, geodesy and surveying, and sea-level change.
SMOS: ESA's water mission
Launched on 2 November 2009, the Soil Moisture and Ocean Salinity (SMOS) mission is making global observations of soil moisture and ocean salinity. By consistently mapping these two variables, SMOS is advancing our understanding of the exchange processes between Earth's surface and atmosphere and helping to improve weather and climate models.
CryoSat: ESA's ice mission
Launched on 8 April 2010, the CryoSat mission is monitoring centimetre-scale changes in the thickness of ice floating in the oceans and in the thickness of the vast ice sheets that blanket Greenland and Antarctica. Together with satellite information on ice extent, these measurements are showing how the volume of Earth's ice is changing and leading to a better understanding of the relationship between ice and climate.
Swarm: ESA's magnetic field mission
Launched on 22 November 2013, Swarm is a constellation of three satellites to measure precisely the magnetic signals that stem from the magnetosphere, ionosphere, Earth's core, mantle, crust and the oceans. This sampling, in both space and time, will lead to an improved understanding of the processes that drive Earth's 'dynamo', which appears to be weakening.
Aeolus: ESA's wind mission
Launched in 2018, the prime aim of the Aeolus mission is to make novel advances in global wind-profile observation and provide much-needed information to improve weather forecasting. Aeolus is expected to pave the way for future operational meteorological satellites dedicated to measuring Earth's wind fields.
EarthCARE: ESA's cloud and aerosol mission
Due for launch in 2022, the Earth Clouds Aerosols and Radiation Explorer (EarthCARE) mission is a European-Japanese mission to improve the representation and understanding of Earth's radiative balance in climate and numerical weather forecast models.
Biomass: ESA's forest mission
The Biomass mission will provide crucial information about the state of our forests and how they are changing. The data will be used to further our knowledge of the role forests play in the carbon cycle.
FLEX: ESA's photosynthesis mission
The Fluorescence Explorer (FLEX) will map vegetation fluorescence to quantify photosynthetic activity. This information will improve our understanding of the way carbon moves between plants and the atmosphere and how photosynthesis affects the carbon and water cycles. It will also lead to better insight into plant health and stress.
The Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission will provide new insight into the planet’s radiation budget and how it is controlled, and therefore improve climate models. More than half of Earth’s outgoing longwave energy is in the far-infrared part of the electromagnetic spectrum, which has not been measured. FORUM will fill this gap.
Earth Explorer 10
In September 2018, the Daedalus, G-Class (now named Hydroterra) and Stereoid (now named Harmony) candidate missions were chosen to enter pre-feasibility study and compete to be the tenth Earth Explorer mission.
Earth Explorer 11
In May 2020, ESA issued a Call for Ideas for Earth Explorer 11.