Spire’s innovative new satellites are designed to enhance soil moisture monitoring

I have extensive experience in GNSS-based remote sensing, having previously worked at Surrey Satellite Technology in the South of England. There, I specialized in electronic hardware designs for platform, satellite, and payload parts. My core was always the GNSS-remote sensing. My PhD focused on designing a remote-sensing payload for GNSS reflections (GNSS-R), developing the onboard processing that allowed for continuous collections.

Following my PhD, Surrey secured a contract with the European Space Agency (ESA) to further develop this technology, resulting in the integration of our payload onto TechDemoSat-1. Subsequently, our payload was included in the NASA CYGNSS mission, a significant achievement as a UK company providing the payload to the NASA CYGNSS constellation of eight satellites.

Then, I started at Spire, and I helped to bring some of those new GNSS-R functionalities, enhancing and building on what we did with CYGNSS, and miniaturizing it from needing a 30 kilogram satellite down to a 5 kilogram satellite. We developed various technologies to miniaturize and optimize cost-effectiveness. Unlike CYGNSS, which could only capture four reflections at a time, our system averages around 24 reflections, significantly expanding our observation capabilities.

The TechDemoSat-1 was launched in 2014, and CYGNSS was in 2016. A couple of years later, we launched our first ones at Spire in 2018. As well as miniaturization, and processing more reflections, we developed a new calibration approach, to solve some of the issues seen in those previous missions. We’ve launched several GNSS-R satellites focused on measuring ocean-surface winds and soil moisture as part of our fully deployed constellation of satellites in orbit.

Could you explain how Spire’s new satellites and their dual sensors are unique?

So far, we’ve launched specialized satellites for monitoring the atmosphere for radio occultation (RO) and separate ones for this GNSS-R application to measure the surface ocean winds and soil moisture. The new satellites combine GNSS-RO and GNSS-R on the same satellite for the first time. Combining these two techniques means that we measure the state of the Earth from the top of the atmosphere down to the ground. GNSS-RO provides precise information on the state of the atmosphere, which is assimilated into weather forecasts at the major meteorology centers.

We measure temperature, pressure, and humidity through the atmosphere, which has major implications on forecast accuracy and uniquely provides a long-term climate record from a calibration-free sensor. The addition of GNSS-R measures Earth’s surface properties, including ocean-surface wind speed and soil moisture over land. These are both impactful observations in improving weather forecasts and monitoring the change in climate and the effects that those changes are having.

Combining GNSS-RO and GNSS-R on the same, less than 5 kg satellite, that is just 30x10x10 cm, is a significant advancement, allowing Spire to observe weather and climate faster. These miniaturized satellites enable us to spread many more satellites around the Earth, observe through the day and night, and be in the right place for extreme weather events.

An illustration of Spire’s combined GNSS-R and GNSS-RO receiver shows the satellite collecting soil moisture and ocean winds from GNSS-R and atmospheric state from GNSS-RO. The signal rays from the GNSS transmitters are shown.

The Spire Global solution to soil remote sensing provides global coverage from the vantage point of low-Earth orbit, making fine-scale observations compared to the existing radiometer satellites. This helps bridge the gap between the point measurements of in-situ sensors and regional soil-moisture trends.

Discover Spire’s Soil Moisture Insights

Typically, we expect an average lifetime of three years for satellites like these.

The satellites will undergo a period of calibration for four weeks, before starting to feed the observations into our near-real-time downlink and processing system for delivery to our customers.

Our Soil Moisture Insights data are available at 6 km resolution, followed by downscaling using synthetic aperture radar data, artificial intelligence, and machine learning to 500 m and 100 m resolutions. Our soil moisture data is available through an easy-to-use API, facilitating smooth integration and analysis within existing systems and applications.

From data collection to delivery, we control the entire value chain, ensuring quality, consistency, and reliability. Compared to other open-sourced and widely used satellite data ($1 billion-dollar science radiometer mission), Spire’s soil moisture monitoring has the added benefit of offering operational continuity, as the institutional science missions near their end-of-life. Our data footprint has 6 km resolution compared to radiometers that start at 36 km. Additionally, we provide daily updates, offering more timely and relevant data for informed decision-making.

Weather prediction can greatly benefit from the use of soil moisture as an input to enhance forecast accuracy for surface temperature and humidity. Some of the industries that will benefit most include commodity traders, parametric insurance, agritech, smart farming, government, data scientists, flood risk modeling, urban planners, environmental managers, and crop yield forecasting.

Spire is a Third-Party Mission data provider for the ESA. Through ESA Earth Online, we are supported to make some data free to the research community. Our historical data is also available through the NASA Commercial Satellite Data Acquisition (CSDA) program (with certain user and latency constraints). We also deliver data in near-real-time to the National Oceanic and Atmospheric Administration (NOAA) as part of a commercial weather data pilot, where our data will be evaluated to improve national weather forecasts.