Understanding Earth’s delicate natural balance and how it is being altered by human activity is not only key to advancing science but also fundamental to acting on environmental issues, the climate crisis, and preparing for their societal impact. With their hallmark of demonstrating novel space technologies and returning scientific excellence, ESA’s family of Earth observing Earth Explorer research satellite missions are world-renowned – and now it’s time for scientists to pitch their new ideas for the twelfth mission in this outstanding series.