Fri, 19 Dec 2025 Just under three weeks after launch, the commissioning of the two HydroGNSS Scout satellites progresses smoothly on orbit. The ESA - HydroGNSS has been steadily bringing subsystems online, validating platform operations, and beginning the first sequences of payload data acquisition. These initial days are always among the most revealing for a mission: they confirm that the hardware is behaving as designed, and they offer the first real-world glimpse of the science these compact missions will deliver.
 
Martin Unwin (SSTL HydroGNSS Principal Scientist) reports:

“Both HydroGNSS Scout payloads are collecting Delay Doppler Maps of reflected GNSS signals. Here (below) is an example of two captured simultaneously onboard HydroGNSS-2 over Central Africa at 09:10 on Friday 5th December, just 7 days after launch. To the left is a reflection from E1 navigation signals generated by Galileo satellite ID27, and on the right is from GPS satellite ID21. The strength of these reflections is related to a number of factors on the surface one of which is the soil moisture, and this parameter will be recovered using processors developed by science partners. The team continues to commission the final systems on the platforms and check over the payload functionality.”


 
Over the coming months, the commissioning teams will continue refining calibration, validating processor chains, and characterising the satellites’ in-orbit behaviour. With both spacecraft healthy and the payloads already generating promising early measurements, HydroGNSS is well on track and moving confidently toward its full operational phase.
 
Pete Garner (SSTL HydroGNSS Project Manager) reports:

“Seeing the first data sets from this exciting mission is a fantastic reward for the SSTL-ESA-Scientific Partners collaborative team that have worked so hard to overcome the many challenges you would expect from a complex satellite project like HydroGNSS, which is operating under the ESA Scout Framework within the Earth Observation directorate at ESA. The whole team is looking forward to what else the spacecraft can show us about our planet.”