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Two European Space Agency (ESA) microsatellites will soon be launched to study climate variables linked to water using GNSS reflectometry. The twin HydroGNSS satellites arrived at Vandenberg Space Force Base in California at the end of September, from where they will be launched later this month.
The HydroGNSS twins are the European Space Agency’s first Scout venture, part of the agency’s Earth Observation FutureEO programme. Scout missions are designed to deliver cutting-edge science quickly and affordably, complementing ESA’s larger Earth Explorer missions.
The identical microsatellites will launch from Vandenberg aboard a SpaceX Falcon 9 rocket, sharing their Transporter-15 ride into orbit with several other small satellites.
Since their arrival, the HydroGNSS satellites have undergone a series of final checks — including testing, propellant loading, battery charging and integration with their launch adapter. Both satellites are now ready for closing of the rocket fairing.
Once in orbit, the two satellites will travel 180 degrees apart around Earth to maximize coverage.
The mission focuses on four crucial variables, all recognized as “essential climate variables” or closely related to them: soil moisture, freeze–thaw state over permafrost, inundation and above-ground biomass. These data are vital for improving our understanding of Earth’s water cycle, including wetlands, permafrost dynamics and forest carbon storage. The data will aid in agricultural planning, flood prediction, and others areas.
Navigation satellites such as GPS and Galileo transmit L-band microwave signals that change when reflected off Earth’s surface. HydroGNSS will compare these reflected signals with the direct GNSS signals to extract valuable information about geophysical parameters related to the water cycle.
New Space missions. Inspired by the principles of New Space, the Scout programme emphasises agility and innovation — using small satellites to miniaturise proven technologies or demonstrate entirely new ways of observing Earth.
Each Scout mission must move from kick-off to launch within just three years and under a budget of €35 million, covering everything from satellite development to in-orbit commissioning. The resulting data are provided as a service to the scientific community and ESA, helping accelerate our understanding of the planet.
