The European Space Agency confirmed that HydroGNSS, its first Scout mission, entered orbit on 28 November after a SpaceX Falcon 9 launched from Vandenberg Space Force Base at 19:44 CET on the Transporter‑15 rideshare. Both UK‑led satellites separated around 90 minutes after liftoff, with first signals received later that evening, according to Surrey Satellite Technology Ltd.
The UK Space Agency said the twin spacecraft were designed and built by Surrey Satellite Technology Ltd in Guildford and backed by £26 million in UKSA funding. The mission is led by the UK and inaugurates ESA’s rapid, lower‑cost ‘Scout’ line of Earth observation missions.
Operationally, HydroGNSS uses GNSS reflectometry: it captures L‑band signals from GPS and Galileo after reflection from Earth’s surface to estimate soil moisture, surface inundation and wetlands, freeze–thaw state in high latitudes, and above‑ground biomass. ESA notes that the technique can retrieve information through cloud and vegetation, enabling frequent, global sampling for hydrology and land services.
ESA’s Scout framework sets tight delivery parameters: missions are to move from kick‑off to launch within three years and remain under a €35 million ceiling, including development, launch and in‑orbit commissioning. HydroGNSS comprises two small satellites in polar orbit at about 550 km, flying roughly 180 degrees apart and delivering measurements at about 25 km resolution.
Policy context sharpened this week. At the ESA Council of Ministers (CM25) in Bremen on 27 November, the UK announced a £1.7 billion investment package for ESA programmes, lifting total UK support to £2.8 billion over the next decade (2025/26–2034/35). HydroGNSS sits within this funding envelope under ESA’s FutureEO portfolio.
Institutional changes are scheduled alongside the programme spend. The UK Space Agency will merge with the Department for Science, Innovation and Technology’s Space Directorate on 1 April 2026, creating a single civil space unit spanning strategy, policy and delivery. UKSA’s 2025–26 corporate plan states the consolidation is intended to reduce duplication and speed decision‑making.
For domestic resilience, the Environment Agency anticipates stronger flood forecasting and warning capability from HydroGNSS measurements, alongside wider use in drought monitoring and agricultural planning. Government material indicates the data are intended to feed climate and hydrological models for public services and research.
UK government and ESA documents state HydroGNSS will complement – rather than replace – existing missions such as ESA’s SMOS and Biomass and NASA’s SMAP by adding a lower‑cost stream of hydrological variables to support continuity and cross‑validation.
SSTL reports HydroGNSS marks its 75th and 76th satellites, delivered in the company’s 40th anniversary year, underscoring the UK’s small‑satellite manufacturing base and supply chain. The mission is part of ESA’s FutureEO programme, with science data provided to ESA and the community as a service by the industrial consortium.
With both spacecraft healthy on orbit, operators now move into in‑orbit commissioning before routine data release. Agencies and research groups planning to use the products should prepare for validation and assimilation testing over the coming months, aligned to ESA’s published approach for Scout missions.