The project aims to demonstrate the capability of Global Navigation Satellite System-Reflectometry (GNSS-R) to detect and quantify microplastics in the ocean. GNSS-R exploits existing L-band transmitters of opportunity and it only requires modified and still miniaturised GNSS receivers to be implemented. GNSS-R is the perfect example of a NewSpace approach to Earth Observation, fulfilling the innovation, cost reduction, and high-risk high pay-off characteristics of the NewSpace, targeting both commercial and science applications, with potential for onboard processing capability, near-real time operations, and incremental development of constellations. Microplastics monitoring is a new application that, despite the potential of forward scattering in bistatic systems, has never been seriously attempted with GNSS-R. GNSS-R could represent a game changer in this field since optical/hyperspectral sensors typically detect the larger floating plastics in the ocean, while microplastics change the spectral properties of the water surface, and these changes are detectable using microwave remote sensing. Preliminary evidence on the potential of GNSS-R for microplastics detection is based on the use of GNSS-R data to sense the sea surface roughness, and the fact that such roughness is lower in regions where microplastics is present compared to regions where there is no microplastics. The initial assessment would be done using data from the UK TDS-1 satellite and the NASA CYGNSS mission, and based on acquisition parameters (e.g. L1 signals, integration time) that are common in TDS-1 and CYGNSS. Since future GNSS-R systems also aim at L5 signals that have a 10 times larger bandwidth and delay-range resolution, a theoretical analysis of what could be expected would also be conducted. If successful, the project will pave the way for observations of microplastics using microwave remote sensing and miniaturised GNSS receiving sensors suitable for NewSpace approaches such as GNSS-R.
