The Far-Infrared Outgoing Radiation Understanding and Monitoring (Forum) Mission. ESA's 9 th Earth Explorer

This paper presents an overview of the Far-Infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission, selected in September 2019 as the ninth Earth Explorer mission of the European Space Agency. The main mission elements are presented, including a description of the payload and platform concepts as defined during the Phase-A preparatory activities, conducted from April 2018 to July 2019.