ESA has chosen two concepts, FORUM and SKIM, to be developed further and compete to be the ninth Earth Explorer mission.
Thanks to new technical developments, the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) candidate would measure radiation emitted from Earth across the entire far-infrared part of the electromagnetic spectrum. Significantly, it measures in the 15–100 micron range, which has never been done from space before.
These observations are important because Earth emits infrared radiation to space, which is affected by water vapour and cirrus clouds, which, in turn, play key roles in Earth’s temperature.
FORUM’s benchmark measurements would improve our understanding of the greenhouse effect and, importantly, contribute to the accuracy of climate change assessments that form the basis for policy decisions.
The Sea-surface Kinematics Multiscale monitoring (SKIM) candidate would carry a novel wide-swath scanning multibeam radar altimeter to measure ocean-surface currents. Uniquely, it uses a Doppler technique, which offers more direct measurements than conventional satellite altimeters.
These new measurements would improve our understanding of vertical and horizontal ocean–surface dynamics over the global ocean every few days. This would lead to better knowledge of how the ocean and atmosphere interact – for example, how atmospheric carbon dioxide is drawn down into the ocean.
SKIM would have particular relevance for understanding the rapidly changing Arctic Ocean, and for observing equatorial regions where conventional satellite altimeters are unable to provide useful measurements of currents.
ESA’s Director of Earth Observation Programmes, Josef Aschbacher, said, “As part of our effort to realise cutting-edge missions, Earth Explorers are built to answer some of the most pressing scientific questions about our planet.
“Out of the 13 concepts that we received following our call for proposals last year, the Earth Science Advisory Committee recommended that FORUM and SKIM enter a competitive feasibility phase.
“With this recommendation now accepted, these two candidates will spend the next two years being studied thoroughly. In 2019, a User Consultation Meeting will be held, after which a decision will be taken by ESA’s Member States as to which of the two contenders will be implemented.
“We foresee Earth Explorer 9 being launched in 2025.”