The European Space Agency’s HydroGNSS Scout satellites are ready for launch it has announced. Surrey Satellite Technology was the prime contractor for the project.

ESA's two HydroGNSS satellites

The series of final checks included propellant loading, battery charging and integration with their launch adapter.

Climate variables
The craft will measure climate variables such as soil moisture, freeze–thaw state over permafrost, inundation and biomass. These are all linked to Earth’s water cycle. Hence the name Hydro.

They will use a technique called Global Navigation Satellite System (GNSS) reflectometry to ‘scout for water’, says ESA.

GNSS
ESA explains that navigation satellites – such as GPS and Galileo – transmit L-band microwave signals. And that these change when reflected off Earth’s surface. HydroGNSS will compare the reflected signals with the direct GNSS signals to extract geophysical information.

The two identical microsatellites will launch aboard a SpaceX Falcon 9 rocket from the Vandenberg Space Force Base in the USA.

Once in orbit, they will then travel 180 degrees apart around Earth to maximise coverage.

Surrey Satellite Technology
As mentioned, Surrey Satellite Technology were among those working on the project. The company was cited by the ESA management team:

“Reaching this milestone is a tremendous achievement, and I am incredibly proud of the entire team behind HydroGNSS,” said ESA’s HydroGNSS Project Manager, Jean-Pascal Lejault.

“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.”

ESA HydroGNSS team

HydroGNSS
HydroGNSS is one of ESA’s new Scout missions being developed within the Earth Observation FutureEO programme.

The satellites arrived at their California launch site at the end of September.