17/04/2024
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As humans exert greater pressure on natural processes, understanding the intricate workings of our Earth system is increasingly vital for effective action on mitigation and adaption strategies. ESA’s Earth Explorer missions yield a wealth of astonishing findings, serving as the bedrock of scientific research in this field. Now, four new concepts have been selected to undergo assessment study, one of which is destined to be the twelfth in this family of world-leading satellite missions.
The selection follows a call for Earth Explorer mission ideas that was issued in early 2023.
From the 17 submissions, which were all thoroughly evaluated, ESA’s Advisory Committee for Earth Observation (ACEO) recommended that four of the ideas should go forward to the assessment study phase.
Today, ESA’s Programme Board for Earth Observation formally accepted this recommendation, which means that the proposed CryoRad, ECO, Hydroterra+ and Keystone mission ideas will now be fully assessed and, in effect, take the first competitive steps towards becoming ESA’s twelfth Earth Explorer.
Simonetta Cheli, Director for ESA’s Earth Observation Programmes, said, “These decisions are always challenging, particularly since the quality of all the proposals that were submitted was very high.
“The mission ideas that will now be further assessed each address key areas of science that would advance knowledge of our Earth system. We thank ACEO and the science community at large for their continuing support in helping us select the best ideas that will fill research gaps and demonstrate new ways of observing our planet from space.”
The four selected mission ideas
CryoRad would fill an important gap in observations of the cryosphere through the direct measurement of low-frequency passive-microwave brightness temperatures using a novel broadband radiometer. From these novel measurements key parameters such as the temperature profile of ice shelves, sea-ice thickness and sea-surface salinity in cold waters can be determined to improve our understanding of key processes in the polar regions. The mission would complement the upcoming Copernicus CIMR, CRISTAL and ROSE-L missions.
ECO would measure the difference between incoming solar radiation and outgoing radiation, which defines Earth’s energy ‘imbalance’, and which fundamentally controls Earth’s climate system. It would be the first time that this imbalance has been measured directly and would help reveal the future trajectory of the climate decades earlier than relying on monitoring global temperature and sea-level rise, as is currently the case. The unique concept envisages a satellite constellation, each carrying four wide field-of-view radiometers to ensure unprecedented coverage, accuracy and stability.
Hydroterra+ would be placed in geostationary orbit, which is unusual for an Earth-science radar mission. From this fixed position above the equator, the satellite’s C-band synthetic aperture radar would deliver data twice a day over Europe, the Mediterranean and northern Africa to understand rapid processes tied to the water cycle and tectonic events in these regions.
Keystone would provide the first direct observations of atomic oxygen in the altitude range of 50–150 km using a unique combination of limb-sounding techniques. These measurements together with observations of composition, temperature and winds would allow scientists to study the processes that drive the variability and energy balance of the mesosphere-lower-thermosphere region of the atmosphere, also looking at the impact of solar cycles and space weather.
These concepts will now undergo assessment phase studies, which will last about 18 months. After this, further down-selections will be made before the successful Earth Explorer 12 mission is selected for implementation.
The family of Earth Explorer research missions are pivotal to ESA’s FutureEO programme. Since the successful launch of the first Earth Explorer in 2009, this extraordinary family of missions, without exception, keep on surpassing expectations.
They continue to demonstrate how breakthrough technology can deliver an astounding range of scientific findings about our planet. Their robust technology leads to many being extended way beyond their planned life in orbit and they gain ever-growing user communities through their scientific excellence and open and free data policy.
Importantly, Earth Explorers also provide sound heritage for developing operational missions. For instance, some of the highly successful current suite of Copernicus Sentinel missions and the future Copernicus Sentinel Expansion missions would simply not be possible without the technology and application opportunities demonstrated by the Earth Explorers.