European Scientists Have Launched the World’s First Space-Borne P-Band Radar. The Goal: Seeing Through the Forests

The European Space Agency (ESA) launched a new Earth observation mission into orbit on Tuesday. The Biomass mission is equipped with the first space-borne P-band synthetic aperture radar, which will allow for the most accurate measurements of the world’s forests to date.

A successful launch. The satellite lifted off successfully on April 29 at 5:15 a.m. ET / 2:15 a.m. PT from Europe’s Spaceport in Kourou in Northern French Guiana aboard a Vega-C rocket. This was the fourth launch for Vega-C, marking its successful return to service after a two-year hiatus caused by a failure during its second flight.

Less than an hour after launch, Biomass successfully separated from the rocket and sent its first signal to confirm that all systems were functioning as planned. The mission is officially part of ESA’s Earth Explorers program, which aims to conduct scientific research on our planet.

Unknown territory. Forests cover nearly a third of the Earth’s surface. They’re often called “the green lungs of the planet.” In fact, they play a crucial role in absorbing and storing around 8 billion net tons of carbon dioxide each year, helping to regulate global temperature.

However, deforestation, forest degradation, and land use changes release stored carbon into the atmosphere, contributing to global warming. This is especially true in tropical regions that host 70% of terrestrial biomass. The challenge is to know how much carbon forests actually store. Scientists also work to understand how they respond to factors such as rising temperatures, increased atmospheric carbon dioxide, and human activity.

Where Biomass comes into play. The satellite will measure, with unprecedented precision, the amount of biomass (and carbon) stored in the planet’s forests, as well as its changes over time. This will enhance the scientific community’s understanding of the carbon cycle and the Earth’s climate system.

Carbon is estimated to be 50% of a tree’s weight. Most of it is stored in the wood (trunk, branches, and stems). Its P-band radar enables Biomass to directly measure the amount of woody biomass globally with remarkable accuracy from space. Woody biomass is the wood beneath the forest canopy and the main reservoir of forest carbon.

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The secret lies in radar technology. Biomass’ main innovation is its primary instrument, which was developed by Airbus. It’s the first space-borne P-band synthetic aperture radar. Radars emit microwaves and analyze the echo that bounces back from the surface. The wavelength is crucial. P-band waves are much longer than those used by other radar satellites such as ESA’s Sentinel-1 (C-band) and NASA’s upcoming NISAR (L-band).

This longer wavelength allows Biomass to penetrate the dense canopy of forest leaves and even pass through clouds and rain. The satellite will interact directly with the woody parts of trees (trunks and thick branches) and the forest floor.

Scientists will then measure how the radar signal scatters upon colliding with these elements. They’ll obtain detailed information about the forest’s structure and estimate its height. Most importantly, the team will be able to calculate the amount of woody organic matter above the ground.

A delicate deployment is upcoming. To effectively project the radar signal, the satellite will soon deploy an impressive 40-foot-wide mesh reflector supported by a 25-foot boom. This is a complex maneuver but essential for the mission’s success.

Biomass will operate in two main phases during its 5.5-year mission. The first phase is an 18-month tomographic phase. During that time, the satellite will make multiple passes over the same areas from slightly different angles to create a 3D map of the forest structure.

The second phase is a 4-year interferometric phase. The satellite will measure changes in forest height and density by analyzing the differences between radar signals. This will allow for an estimation of the variation in biomass over time.

Since around half of that biomass is carbon, the mission will indirectly but accurately map where and how much carbon is stored in the forests and the rate at which it’s being emitted.

Image | ESA

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