ESA’s Biomass on track to target forests

With more than 100 global leaders at COP26 having pledged to halt and reverse deforestation and land degradation by the end of the decade to help address the climate crisis, the health of the world’s forests is high on the political agenda. ESA’s Biomass mission will soon play a key role in delivering novel information about the state of our forests, how they are changing over time, and advance our knowledge of the carbon cycle. With launch scheduled for 2023, the mission is now in its last phases of development, having recently passed several key milestones.

The COP26 pledge on deforestation and degradation from over 100 leaders representing more than 85% of the world’s forests is clearly good news in the battle to redress the balance between the amount of carbon dioxide emitted to the atmosphere through human activity and the amount absorbed by Earth’s carbon sinks. Forests, are, of course an important carbon sink. However, forest degradation and deforestation, particularly in tropical regions, are causing much of this otherwise stored carbon to be released back into the atmosphere, exacerbating climate change. In fact, recent research, shows that the Amazon rainforest is now actually releasing more carbon dioxide to the atmosphere than it absorbs. Even with the new pledge in place, quantifying the global cycle is essential to understanding the how forests are changing and the subsequent implications for our climate.

ESA’s forest mission, Biomass, will use a novel measuring technique to deliver completely new information on forest height and above-ground forest biomass from space. Forest biomass not only includes the tree trunk, but also the bark, branches and leaves.

Global carbon budget
Measurements of forest biomass can be used as a proxy for stored carbon – but this is poorly quantified in most parts of the world. Data from the Biomass mission will reduce the major uncertainties in calculations of carbon stocks and fluxes on land, including carbon fluxes associated with land-use change, forest degradation and forest regrowth. This will lead to a better understanding of the state of Earth’s forests, how they are changing over time, and advance our knowledge of the carbon cycle. However, mapping forest biomass from space is a huge technical challenge. Forests are complex structures – and different tree species and dense canopies make them difficult to measure.

Rising to the challenge, ESA’s Biomass satellite will use a specific type of radar instrument that can see through clouds, which typically shroud tropical forest, and penetrates the canopy layer, allowing the biomass of trees to be estimated. It will be the first satellite to carry a fully polarimetric P-band synthetic aperture radar for interferometric imaging. Thanks to the long wavelength of P-band, around 70 cm, the radar signal can slice through the whole forest layer. Scheduled for liftoff in 2023, the development of the mission is well on the way and completion is in sight. ESA’s Biomass Project Manager, Michael Fehringer, said, “The build of the satellite involves more than 50 industrial teams all over Europe and one major supplier in the US. The satellite platform, everything except the radar instrument, is currently being assembled at Airbus in Stevenage in the UK. Most of the avionic units such as the onboard computer, the power control unit and the reaction wheels to control the satellite’s motion have already been mounted onto the structure. And, the first switch-on of the satellite has taken place already.