GALILEO
SSTL developed and delivered the first operational payload for Galileo, Europe's satellite-supported navigation programme, as part of the GIOVE-A satellite mission, launched in 2005.
Between 2010 and 2020 SSTL supplied 34 navigation payloads for Galileo, with a payload solution based on European sourced atomic clocks, signal generators, high power TWTAs and Antennas.
SSTL's Galileo navigation payload during assembly
GIOVE-A satellite
GNSS Receivers and Antennas
Our Space GNSS receivers (SGRs) are highly regarded for quality and robustness and are flying on most of our own satellites and many other spacecraft.
Space GNSS Receivers routinely provide position, velocity and time information to satellites in low Earth orbit, and more than 70 orbiting satellites have used receivers and antennas provided by SSTL, on missions from UKSA, ESA, NASA, USAF, JAXA, RemoveDEBRIS and on the International Space Station. SSTL’s receivers are based on COTS components, with radiation mitigation and quality processes to suit small satellite applications.
GNSS Reflectometry
GNSS Reflectometry (GNSS-R) is an Earth observation technique that uses GNSS signals as L-Band radar sources, allowing the satellite to take measurements of ocean wind speeds, polar ice and hydrological land parameters at a higher spatial resolution and an order of magnitude lower cost than other common methods.
SSTL has pioneered the new field of GNSS-R with payloads provided and flown successfully on UK-DMC, TechDemoSat-1, the NASA CYGNSS constellation and DoT-1. SSTL is the industrial lead for the ESA Scout HydroGNSS GNSS-R mission.
GNSS-R can be used for sensing many geophysical parameters which in turn support climate and meteorological applications, such as:
- Ocean wind speed – Winds affect the roughness of the ocean surface and can be derived from the strength of reflected signals
- Sea ice extent – Reflections off ice are usually stronger than off ocean surfaces allowing differentiation from space
- Soil moisture – Reflections become stronger as the soil becomes wetter due to change in permittivity
- Inundation – Inundated areas are flat and induce strong coherent reflections visible even from under vegetation.
- Freeze-thaw state – the permittivity of the soil changes significantly when the water content freezes.
- Forest biomass – the above ground vegetation attenuates reflected signals so is a parameter that can be observed from space.
ESA Scout - HydroGNSS mission
SSTL leads the ESA Scout HydroGNSS project, comprising two 70kg small satellites used to operate a science mission with GNSS-R as the primary payload. The HydroGNSS mission concept makes use of GNSS-R innovations such using both GPS and Galileo signals (with the potential for future expansion), dual frequency, dual polarisation and coherent signal acquisition to measure variables closely linked with Essential Climate Variables (ECVs) over land: Soil Moisture, inundation, permafrost freeze/thaw, and biomass, with secondary targets of surface wind speed and sea ice extent over the ocean. SSTL provides free and open access to registrants according to ESA’s data policy via the HydroGNSS website.
Discover more about the HydroGNSS mission