BIOMASS will have a 12m reflector to catch the returning radar signal
A satellite that can weigh the Earth's forests has just been given the go ahead by the European Space Agency.
BIOMASS, as it will be known, is expected to launch in 2020.
The spacecraft will carry a novel radar system that is able to sense the trunks and big branches of trees from orbit.
Scientists will use BIOMASS to calculate the amount of carbon stored in the world's forests, and to monitor for any changes over the course of the five-year mission.
The satellite's data should help researchers understand better the role trees play in the cycling of carbon on Earth and, by extension, the influence this has on the planet's climate.
"BIOMASS will give us unprecedented knowledge on the state of the world's forests and how they are changing," said Prof Shaun Quegan, who was one of the key proposers of the mission.
"This will give us a firm basis for treaties that aim to help developing countries preserve their forests, such as the UN Reducing Emissions from Deforestation and forest Degradation (REDD+) initiative.
"But for every country in the world, BIOMASS will return information on their national forestry resources, and that's important for things like energy and biodiversity," the Sheffield University researcher told BBC News.
Esa's Earth Observation Programme Board approved BIOMASS on Tuesday.
The satellite will be the seventh of the agency's so-called Earth Explorers - a series of spacecraft that are designed to do innovative science in obtaining data on issues of pressing environmental concern.
Three missions have so far gone into orbit, returning remarkable new information on gravity, polar ice cover, soil moisture and ocean salinity.
A fourth, to study Earth's magnetic field, launches in the coming weeks; with satellites to study the wind and fine particles in the atmosphere further back in the development schedule.