ESA's Satellite for Forest Monitoring: Key Information on the Upcoming Biomass Mission

The European Space Agency (ESA) is set to launch its latest mission, aimed at mapping the world's forests, later this month. This initiative, referred to as the Biomass mission, will gather crucial data regarding the condition of the planet's forests and their transformations, thereby enhancing our understanding of the forests' role in the carbon cycle.

Scheduled for liftoff on April 29, the mission will be launched aboard the Vega C rocket from the European spaceport located in French Guiana. It will be positioned in a sun-synchronous orbit (SSO) at an altitude of approximately 666 kilometers, allowing it to maintain alignment with the Sun.

The Biomass mission marks the seventh endeavor under ESA's Earth Explorer program, which has previously deployed satellites to monitor various elements of the Earth's system.

What objectives does the Biomass mission aim to achieve?

Forests play a critical role in the global carbon cycle by sequestering significant amounts of carbon. Scientists estimate that forests absorb around 16 billion metric tons of carbon dioxide (CO2) annually and currently store approximately 861 gigatons of carbon within their branches, leaves, roots, and soils.

However, there is a notable deficiency in data regarding above-ground biomass—the total mass of living organisms above the forest floor—and forest height across extensive geographical areas. Consequently, our understanding of forest conditions, their contributions to the carbon cycle, and their impact on climate remains limited. The primary goal of the Biomass mission is to address this knowledge gap.

Additionally, the mission will enable scientists to more precisely assess changes in carbon levels as deforestation continues and atmospheric CO2 concentrations rise. In 2023, an estimated 3.7 million hectares of tropical forests were lost, which translates to the loss of approximately ten soccer fields of forest every minute, according to a report from the World Resources Institute. The report indicated that this deforestation accounted for roughly six percent of the estimated global carbon dioxide emissions in 2023.

Simonetta Cheli, the director of Earth Observation Programmes at ESA, stated to the Observer, “Understanding the health of our tropical forests is essential… We must assess the quality and diversity of their vegetation, as well as the carbon stored within them. To obtain this data, we will create three-dimensional images that capture everything from the forest canopy to the roots of the trees.”

In addition to monitoring forests, the Biomass mission will track the movement of ice sheets in Antarctica and produce digital models of areas covered by dense vegetation.

How will the Biomass mission monitor forests?

To achieve its goals, the mission will employ synthetic aperture radar (SAR), a satellite imaging method that utilizes radar waves to map the Earth's surface. This SAR sensor will function within the long-wave P-band frequency range, with a wavelength of 70 cm. Unlike other SAR sensors that operate at shorter wavelengths, the P-band SAR can penetrate forest canopies to evaluate the carbon stored on the forest floor and in the branches of trees, as well as to monitor changes in these levels. The sensor will also provide estimates of forest biomass.

Significantly, Biomass is the first satellite globally to be equipped with a P-band SAR. It features a large 12-meter antenna that will be deployed as the satellite begins its orbit around the Earth.

Shaun Quegan, a researcher at Sheffield University and the leader of the Biomass science team, remarked to The Guardian, “Essentially, the mission will measure the weight of the forests it examines… We know that half of that weight consists of carbon. Thus, we will be able to quantify the carbon content of the world’s forests from space and, importantly, determine how this is changing over time. This will allow us to understand the carbon balance between the atmosphere and the forests, which is critically important.”