Rainforests are frequently described as the “lungs of the Earth” due to their critical role in carbon storage and climate regulation.
They sequester billions of tonnes of carbon, mitigating the effects of climate change.
However, with an estimated one and a half trillion trees, determining their total carbon storage has been an immense scientific challenge—until recently.
On Tuesday, the European Space Agency (ESA) launched a pioneering satellite equipped with advanced radar technology designed to uncover data hidden beneath dense forest canopies.
This mission is expected to enhance scientific understanding of the vital role rainforests play in carbon sequestration and the consequences of deforestation.
The launch took place at ESA’s Kourou facility in French Guiana, with the spacecraft set to survey regions including the Amazon rainforest.
The satellite, nicknamed “space brolly”, features a notable 12-meter-wide antenna designed to transmit signals into the forest.
“We really want to interrogate these forests. We can actually look inside,” said Prof John Remedios, director of The National Centre for Earth Observation and a key proponent of the mission.
He highlighted the ambition of achieving—for the first time—precise measurements of carbon content in rainforests such as those in the Amazon, Congo, and Indonesia.
The satellite uses P-band radar, a system with an especially long wavelength, which enables it to penetrate thick foliage and capture data from both branches and tree trunks.
“Most spaceborne radars today can produce remarkable images of icebergs, but when targeting forests, they mainly detect surface leaves and twigs,” commented Dr Ralph Cordey, Airbus head of geosciences.
“By utilizing a much longer radar wavelength, we can now peer deep into the forest structure,” he added.
Weighing 1.2 tonnes, the satellite employs a scanning technique akin to a CT scan, generating cross-sectional images of forest layers over repeated passes to estimate the volume of woody material—and, by extension, carbon storage.
This woody material serves as a key indicator for the quantity of stored carbon dioxide, crucial for evaluating climate impacts.
Previously, researchers relied on sampling individual trees and extrapolating data—an approach Professor Mat Disney from University College London described as a “huge challenge.”
“Our current understanding is really patchy, because it’s really, really difficult to measure,” he noted. “We are effectively trying to weigh the carbon in one and a half trillion tropical trees.”
“Satellites are really the only way you can do that consistently.”
Ground-based measurements will continue post-launch to validate the satellite’s data outputs.
Constructed in the UK and first envisioned by Professor Shaun Quegan of the University of Sheffield, the mission embodies international collaboration. “The project is the culmination of decades of groundbreaking work involving top scientists from Europe and the US,” Quegan remarked.
Despite extensive preparation and testing, several technical challenges remain as the satellite continues its deployment process.
“Certain elements, like the deployable 12-metre antenna, are exceptionally large. It resembles opening an umbrella in orbit—though on a much grander scale,” Dr Cordey explained.
For the construction of the antenna-reflector, Airbus collaborated with engineers from U.S.-based L3Harris Technologies, specialists in large deployable systems not currently available in Europe.
The mission team aims to deliver the first comprehensive forest maps within six months, continuing observation and data collection over the following five years.
These annual maps will not only quantify carbon reserves but will also track losses resulting from deforestation.
“Traditional satellite observations, like those from the Landsat network, are often hindered by persistent cloud cover in the tropics,” said Prof Disney.
An important advantage of the Biomass satellite’s longer radar wavelength is its ability to penetrate clouds, delivering reliable and comparative forest data year after year.
This capability has been a primary motivation for the dedicated scientists who have driven this project for over two decades.
“It’s exciting because it will illuminate the hidden contributions of forests—resources we often take for granted—to the planetary systems that regulate climate change,” Dr Cordey reflected. “Understanding this has never been more important.”
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