HydroGNSS: UK leads ESA’s first ‘Scout’ climate mission into orbit
Source: gov.uk (2025-11-29)

The UK has taken a major step forward in space-based climate science with the successful launch of HydroGNSS, a new pair of satellites that will monitor the planet’s water cycle from space.

Launched on 28 November aboard a SpaceX rocket, HydroGNSS is the very first mission under the European Space Agency’s (ESA) Scout programme and is led by the UK.

Designed and built by Surrey Satellite Technology Ltd (SSTL) in Guildford, HydroGNSS is backed by £26 million in funding from the UK Space Agency. The mission highlights the UK’s industrial and scientific excellence in satellite innovation and climate monitoring.

Space Minister Liz Lloyd said:

The launch of HydroGNSS is yet another success story for British space innovation. Backed with government funding, this UK-built satellite will play an invaluable role up in space, helping tackle some of the most pressing environmental challenges we face on Earth.

As we build the UK’s space capabilities, groundbreaking missions like HydroGNSS demonstrate that Britain is at the forefront of space technology that delivers real-world impact for people and our planet.

Now in orbit, HydroGNSS will help scientists track how water moves around our planet. By measuring how wet or dry the ground is, identifying areas where water is pooling or flooding, detecting whether the land is frozen, and estimating how much vegetation covers the Earth’s surface, HydroGNSS will provide crucial data for weather forecasting, flood prediction, and agricultural planning. These insights will also help researchers monitor the health of ecosystems and better understand the long-term impacts of a warming climate.

HydroGNSS uses an innovative technique called GNSS Reflectometry, which picks up signals from existing navigation satellites after they bounce off the Earth’s surface. This clever approach means the satellite can gather data even through thick cloud cover and dense forests, conditions that often block traditional sensors. As a result, HydroGNSS offers a cost-effective and dependable way to monitor environmental changes across the globe.

Andrew Cawthorne, Managing Director, Surrey Satellite Technology Ltd said:

It’s a proud moment to see both HydroGNSS satellites successfully launched and sending back their first signals from orbit.

This mission is a fantastic example of how the UK, working through ESA and with support from the UK Space Agency, is delivering world-class climate science from space. HydroGNSS represents SSTL’s 75th and 76th satellites, launched in our 40th anniversary year, and showcases the strength and innovation of the UK’s space industry at the heart of Europe’s environmental monitoring efforts.

The satellites will deliver frequent, global measurements that feed into improved climate models and help researchers better understand the dynamics of the water cycle. This data will be used to assess the impact of climate change on ecosystems, inform agricultural planning, and support disaster response efforts in regions affected by droughts, floods, and other extreme weather events.

Paul Clements, Director of Operations at the Environment Agency, said:

Climate change means more frequent and severe environmental incidents across the UK. Now more than ever, we must harness cutting-edge technology to develop the tools we need to protect communities from flooding and other hazards.

The launch of this new mission is a compelling example of how British leadership and expertise in space delivers real, tangible benefits to the public. The enhanced data it provides will significantly strengthen our flood forecasting and warning capabilities, enabling a more effective operational response to safeguard lives, property, and infrastructure.

HydroGNSS complements existing missions such as ESA’s SMOS (Soil Moisture and Ocean Salinity) and Biomass, and NASA’s SMAP (Soil Moisture Active Passive), contributing to a broader international effort to monitor and mitigate environmental impacts. By providing high-value science at low cost, the mission demonstrates how small satellite technology – a key UK strength - can play a big role in tackling global challenges.

Simonetta Cheli, Director of Earth Observation Programmes, ESA said:

As the first of ESA’s Scout missions to launch, HydroGNSS marks an important milestone for this new family of rapid, low-cost Earth observation missions. It serves as a reminder of the maturity of the Earth observation sector in the UK and we extend our thanks to the mission’s prime contractor, SSTL.

The launch also represents a key step in the evolution of our FutureEO programme, where the Scouts embody a fast, agile, innovative and cost-efficient approach – complementing our larger Earth Explorer missions. We now look forward to seeing how HydroGNSS will employ GNSS reflectometry to deliver valuable insights into key hydrological variables that shape Earth’s water cycle.

The mission highlights the UK’s growing leadership in space, which is vital for the economy and national security, as well as the strong collaboration with the European Space Agency and industry partners. The UK space sector generates an annual income of £18.6 billion and supports more than 55,000 jobs.

The successful launch comes at a pivotal moment in the evolution of the UK Space Agency, ahead of its integration into the Department for Science, Innovation and Technology (DSIT) from 1 April 2026. The merger will create a single civil space unit, streamlining strategy, policy, and delivery, building on recent achievements and ensuring the government supports the UK space sector effectively. It also comes after the UK agreed a £1.7 billion investment package (https://www.gov.uk/government/news/growth-and-security-at-the-forefront-in-uk-funding-boost-for-european-space-agency) in European Space Agency (ESA) programmes at the ESA Council of Ministers in Bremen, boosting the UK’s total commitment to £2.8 billion over the next decade.

The delivery of HydroGNSS further strengthens UK’s reputation as a hub for small satellite innovation, commercialisation and cutting-edge Earth observation.