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ESA’s Biomass Satellite Prepares for Upcoming Launch

Three weeks after arriving at Europe’s Spaceport in French Guiana, the European Space Agency’s (ESA) Biomass satellite is undergoing essential preparations ahead of its scheduled launch on April 29. Satellite engineers are diligently working through an extensive checklist to ensure every aspect of this new Earth Explorer mission is ready for liftoff. The latest update highlights that the satellite’s propulsion subsystem has been successfully prepared for fuelling and has undergone rigorous system evaluations.

The check-out operations were carried out by the OHB-Sweden team, who achieved this significant milestone a full day ahead of the planned timeline.

Technical Overview of the Propulsion Subsystem

For those with a keen interest in engineering specifics, the propulsion subsystem consists of several meters of tubing that facilitate the movement of hydrazine propellant from a 177-liter tank to each of the eight thrusters strategically located at the four corners of the satellite.

This system is designed with multiple valves to control propellant flow, enabling both fuelling and pressurization. Among these, there are flow control valves, latching valves, and service valves.

Each thruster has two series-configured flow control valves, both of which must be opened for thruster activation. For added safety, these valves are normally closed; they remain shut unless powered, as internal magnets inhibit movement.

Additionally, the propulsion system is segmented into two branches, each featuring four isolated thrusters, separated from the main tank by latching valves. These bistable valves retain their state—open or closed—until actively switched, giving engineers the flexibility to isolate or activate a complete branch as needed.

At this point, extensive leak checks have been performed on all valves. This testing involves pressurizing one side of a closed valve with helium while creating a vacuum on the downstream side. A helium detector is then used to identify any gas leaks. Given the complexity of the internal dimensions, these tests require significant time and accuracy.

With all checks completed successfully, the propulsion system is now secure against any loss of propellant after it is loaded, marking a critical step towards successful fuelling.

The thorough testing of the propulsion subsystem, while demanding and time-consuming, is vital for ensuring the mission is fully prepared for the April launch aboard a Vega-C rocket.

Biomass Mission Goals

Once operational in orbit, the Biomass mission is set to significantly contribute to our understanding of forest ecosystems, tracking changes over time and enhancing the knowledge of the carbon cycle. Notably, it will be the first satellite equipped with a fully polarimetric P-band synthetic aperture radar for interferometric imaging. This technology utilizes the long wavelength of P-band, approximately 70 cm, allowing it to penetrate the forest layers and measure biomass—the woody trunks, branches, and stems where trees store the majority of their carbon.

Source
www.esa.int