ESA’s HydroGNSS Scout satellites are set for launch, marking a major milestone in the European Space Agency’s efforts to enhance Earth observation through innovative small satellite missions. These twin satellites are designed to monitor critical climate variables linked to water, offering valuable insights into our planet’s water cycle. As the mission nears its liftoff, the focus is on how they will help us better understand issues such as soil moisture, flood prediction, and permafrost dynamics.
ESA’s HydroGNSS Scout Satellites: Ready for Their Mission to ‘Scout for Water’
The European Space Agency’s (ESA) first Scout mission, HydroGNSS, is now ready for launch. After careful preparation at the California launch site, the two identical microsatellites are poised to embark on their journey aboard a SpaceX Falcon 9 rocket. HydroGNSS represents a major leap in Earth observation, utilizing GNSS (Global Navigation Satellite System) reflectometry to provide critical data on water-related climate variables.
ESA’s HydroGNSS Project Manager, Jean-Pascal Lejault, emphasized the team’s dedication in making this mission a reality: “Reaching this milestone is a tremendous achievement, and I am incredibly proud of the entire team behind HydroGNSS. Developing ESA’s first Scout mission within such a tight timeframe and budget has required exceptional dedication and ingenuity. My special thanks go to our prime contractor Surrey Satellite Technology Ltd in the UK and the ESA project team—their commitment and creativity have made HydroGNSS possible.”
The HydroGNSS mission marks a key step in ESA’s Earth observation program, delivering timely scientific results while keeping costs low. The satellites are designed to move 180 degrees apart in orbit to maximize their coverage, providing a global view of key climate variables. HydroGNSS is part of the FutureEO program, which focuses on agile, cost-effective Earth monitoring solutions.
What is GNSS Reflectometry? How HydroGNSS Scouts the Water Cycle
The core technology behind HydroGNSS lies in Global Navigation Satellite System (GNSS) reflectometry, an innovative technique that leverages the signals from satellites like GPS and Galileo. These navigation satellites transmit L-band microwave signals, which change when they bounce off the Earth’s surface. By comparing the reflected signals with direct ones, HydroGNSS can extract valuable geophysical data about our planet’s water cycle.
This method is particularly useful for monitoring soil moisture, freeze-thaw states, and inundation, as well as for gauging the above-ground biomass of forests. These four key variables are crucial for understanding Earth’s hydrological processes and have significant implications for agriculture, climate change, and flood management. The data collected will help scientists gain a clearer picture of the global water cycle, improving flood prediction models and enhancing agricultural planning.
HydroGNSS provides measurements of key hydrological climate variables, including soil moisture, freeze–thaw state over permafrost, inundation and wetlands, and above-ground biomass, using a technique called Global Navigation Satellite System (GNSS) reflectometry. In doing so it complements missions such as ESA’s SMOS and Biomass, Copernicus Sentinel-1 and NASA’s SMAP. The satellite measures the signal reflected off the land, ice and ocean from existing GNSS missions such as Galileo and GPS. Credit: ESA/ATG medialab
ESA’s First Scout Mission: A New Era in Small Satellite Science
HydroGNSS is not only a breakthrough mission in terms of technology but also in the way it was conceived. As ESA’s first Scout mission, it embodies the principles of the “New Space” movement, which focuses on rapid, cost-effective development. With a mission budget capped at €35 million and a development cycle of just three years, HydroGNSS exemplifies ESA’s push for agility in space science.
The Scout program is designed to deliver high-impact scientific missions within tight timeframes and budgets. HydroGNSS, for instance, is set to launch just three years after the project’s inception—a remarkable feat in the world of space missions. As part of ESA’s Earth Observation program, the Scout missions serve as a complement to larger, more complex Earth Explorer missions. Through such innovative and quick-turnaround projects, ESA is reshaping the landscape of Earth observation.