Photo: ©ESA/ Airbus Defence and Space
The Biomass mission from the European Space Agency (ESA) has been in development for over a decade, but the problem it was designed to solve still remains: a lack of knowledge about global forest carbon and how it changes. Due for launch on April 29, 2025, Biomass will be the first (civilian) long wavelength radar to be flown in space, giving greater insights into the structure and carbon content of the world’s tropical forests than any other satellite mission before it.
The data will be free to access and have a license for commercial use. It will not have global coverage. North America and Europe will be excluded due to concerns over radio frequency interference with military radars.
Earth Blox verdict
The final data products from the ESA Biomass mission will be a game-changer, providing never-before-seen information about the carbon contained in the densest tropical forests. We will have to be patient, though, as the first products won’t arrive for 12 months or more.
Pros:
✅ This is the first time that long wavelength radar has flown in space, so the imagery might show some things we never quite expected.
✅ Data products will give information on the vertical structure of the forest, providing improved estimates of the carbon content.
✅ Unlike GEDI (NASA’s canopy laser), Biomass will give wall-to-wall coverage over the tropics.
✅ It will be free to access and have a commercial licence.
Cons:
❌ Coverage is not global. North America and Europe are not included.
❌ Despite claims it will give excellent forest Biomass maps, it might struggle in very dense forests of the wet tropics.
❌ The spatial resolution is several hundred metres, so may be limited for project-level analysis.
❌ Radio frequency interference is a potential problem, the extent of which is yet to be determined.
❌ It is likely to be more than 12 months before we see any data products.
❌ There is no historical data to directly compare it with.
Technical specs
- Ground sample distance (pixel size): 200m for the above-ground Biomass and forest height products; 50m for the severe deforestation product.
- Coverage: Global terrestrial surface, except for North America (including much of Central America) and Europe. Some other areas may be subject to radio frequency interference.
- Metrics: Maps of above-ground Biomass and forest height across the tropics. A severe forest disturbance product, which maps areas of deforestation.
- Frequency: The standard images should be approximately a fortnight apart, but global products will be updated in 6-month intervals.
Expert review by Iain H Woodhouse
What is the mission?
Uncertainty in our estimate of how much carbon is contained within the world’s forests is still a major gap in our understanding of the Earth’s climate system. Biomass was conceived to reduce those uncertainties using a radically new radar system that uses the longer wavelength P-band radar frequency. This will provide 3D carbon data from the highest density forests that have always proved difficult to measure with existing satellite sensors.
Biomass is an ESA mission, and while born in the UK, it was brought to life by a team of international scientists from the UK, France, Denmark, Greece, Germany, United States, Italy, Sweden and Austria, along with more than 50 industrial teams.
It is a trailblazer for a number of reasons:
- 1st ESA Earth Explorer research mission conceived and built in the UK
- 1st use of P-Band radar used in space (civilian)
- 1st systematic measurements of height from satellite radar
- 1st use of tomography in space
- With a 12m antenna, it is the largest reflector antenna in space
What kind of data will we get?
Biomass is an imaging radar satellite that uses the technique of Synthetic Aperture Radar (SAR). Unlike regular cameras, SAR uses radio waves instead of light. It operates day and night and can see through clouds, meaning that image collection is guaranteed.
SAR works by sending out pulses of radio waves then measuring the signals that bounce back. With Biomass, these signals have a very long wavelength (70cm), which means the signal can get through the upper canopy of a forest and retrieve signals from the trunks and larger branches. This is why it is more sensitive than other sensors to how much plant material (the Biomass) is contained within the forest. The range-measuring property of radar also allows it to determine the height of the forests. These two measurements combined should give improved estimates of forest carbon content across the entire tropics.
How does the data perform?
The short answer is that we are not completely sure. There have been airborne campaigns that have carried similar radar systems across several areas of the tropics, but a 70cm wavelength radar has never flown in space before, so we may find surprising results in areas that haven’t been mapped in this way before.
There have been some concerns about the accuracy of such systems in the densest tropical forest regions. Because the spatial resolution is several hundred meters, it remains to be seen whether this data will be detailed enough for project-based surveys. However, the science value is undeniable. Biomass will provide new data across the tropics that will help scientists better understand tropical forest ecology and carbon storage.
It will also prove vital for cross-calibrating other methodologies. In time, we can expect a flurry of new higher-resolution forest carbon products that have used the Biomass products to train a machine-learning model on data, such as Sentinel 2.
One further unknown is radio frequency interference (RFI). The radio spectrum is jam-packed with other users (other radars, mobile communications, etc), so there is a risk of interference that will impact data collection from Biomass. National militaries across the world do not always declare the radars they have or the wavelengths they operate at. It would not be a complete surprise if we find RFI in areas we didn’t expect due to undeclared radar installations.
What level of detail does it detect?
ESA's Biomass algorithms have been in development for over a decade, with the support of several airborne campaigns that replicated Biomass data collection. While the resulting canopy height products may not be as accurate as those from NASA's GEDI (a canopy laser on the International Space Station and a key input for most global forest carbon maps), they will provide comprehensive wall-to-wall coverage, unlike GEDI's incomplete data strips.
Similar products
Earth Blox offers a range of global forest Biomass products today, such as Chloris Geospatial’s Biomass data, Planet’s Forest Carbon Monitoring data, and ESA Above Ground Biomass. All of these data sets perform best at the low to middle end of the forest carbon scale, but you really need long wavelength radar to tie down the uncertainties at the very high end. Even GEDI struggles to “see” enough of the forest when it is extremely tall and dense. Biomass should overcome that, and we expect to see this data integrated to improve these existing products.
Suggested alternatives
Chloris Geospatial: Aboveground Biomass Stock and Change (10m)
Annual data on aboveground Biomass, carbon stock and carbon change since the year 2017. At 10m resolution and quantified uncertainty for every pixel.
Forest Carbon from Planet (30m and 3m)
Aboveground carbon, canopy height and percentage cover. Forest Carbon Diligence Product (from 2013 at 30m) and Forest Carbon Monitoring product (quarterly updates at 3m).
ESA Above Ground Biomass (100m)
Forest above-ground Biomass estimates, also based on radar data, for years 2010, 2017, 2018, 2019, 2020 and 2021 with global coverage.
Biomass Carbon Density Maps 2010 (300m)
Provides global baseline estimates of above and below-ground Biomass for the year 2010 on a similar pixel size to Biomass.
Earth Blox GEDI Global Biomass 2020 (30m)
Global forest Biomass estimate produced by the Earth Blox team based on canopy height for the year 2020.
Explore the Earth Blox data catalogue here.
Iain H Woodhouse
Iain H Woodhouse is Knowledge and Outreach Lead at Earth Blox and Professor of Applied Earth Observation at the University of Edinburgh. He specialises in active remote sensing, with over 27 years experience in academia and industry, and more than 100 publications. Iain has advised multiple UK government agencies on EO strategy and is former Chair of the UK Space Agency’s EO Advisory Committee.