EO·Atlas
HydroGNSS (ESA Scout)
Two-microsat ESA Scout constellation launched November 2025; GNSS-R instruments receive GPS and Galileo reflections to measure soil moisture, freeze-thaw state over permafrost, wetland inundation, and above-ground biomass at 500-600 km SSO.
HydroGNSS is an ESA Scout mission consisting of two microsatellites launched on 28 November 2025 into a sun-synchronous orbit at 550 km altitude and 98-degree inclination. As of mid-2026 the mission is in the commissioning phase, with science data release expected in July 2026.[1][2]
Each spacecraft carries an SGR-ReSI-Z GNSS reflectometry receiver designed to measure reflected GPS and Galileo signals and to derive soil moisture, freeze-thaw state of permafrost, wetland inundation extent, and above-ground biomass. The SGR-ReSI-Z is a new generation of the SGR-ReSI instrument flown on TechDemoSat-1, which demonstrated spaceborne GNSS-R ocean wind retrieval in 2014, and builds on techniques validated on the CYGNSS constellation.[3]
The two-satellite configuration provides repeat coverage to support seasonal monitoring of permafrost dynamics and flood inundation in high-latitude and wetland regions.[3][1]
- [1]HydroGNSS/Scout-2 mission overview, eoPortalagency doc2026-06-11
- [2]ESA HydroGNSS launched to scout for wateroperator press2026-06-11
- [3]HydroGNSS satellites proving in-orbit capabilities, SSTL 2026operator press2026-06-11