About 10 million tons of mismanaged plastic waste are dumped into the oceans every year. It persists in water for several decades before degrading. The embedded chemical additives are toxic to all types of marine life, which absorb or ingest it, ultimately reaching the human food chain. This has become a global problem, demanding permanent monitoring, which is only possible with the global geographic reach of satellites.
Despite the urgency, the topic of remote unsupervised detection of floating marine waste is still in its infancy. There is no evidence yet of which technology is best. Most of the current research focuses on optical sensing, in the visible and near-infrared spectrum. However, bad weather and unfavorable light conditions easily hamper these techniques, preventing continuous tracking.
Microwaves (MW) do not suffer significant atmospheric impairments and can reveal new scattering or emission features of floating marine macro-plastic (pieces larger than one cm). Although MW is a mature technology for several land and sea Earth Observation missions, fundamental research work is still needed to find the best MW sensing techniques (among passive or active), best frequency bands, and best signal processing algorithms for marine litter detection. There is almost no such prior work or related published data.
This is the goal of MARES project run by IT since October 2021, promoted and funded by The European Space Agency. Two exploratory measurement campaigns were already conducted in DELTARES facility in Netherlands, a 75 m x 9 m basin that can reproduce deep ocean waves. Several teams across Europe gathered for these tests to compare each other’s techniques and results for the same scenario. The team form IT and University of Stirling (UK) tested radar technologies, researchers from Universities of Leiden, Twent (NL), and Oldenburg (DE) tested optical technologies, and teams from TUD (NL) and University of Alberta (CA) exploited the water dynamics to infer the presence of plastic litter.
According to Carlos Fernandes, project coordinator, “so far, results have shown a good correlation between the increase in scattered signal levels and the presence of floating plastic. These very promising results warranted the continuation of the interest of ESA in exploring further this line of research, aiming at the definition of a future instrument to operate on a satellite”.
Carlos Fernandes stresses that “MARES project strengthens IT engagement with National Public Policies for the environment and with the United Nations Strategic Goals, namely for the Oceans."
The project involves a large team from the Antennas and Propagation Group, in Lisbon and Leiria, and from the Pattern Recognition and Automatic Learning Group, in Lisbon.
Photo credits: Instalações da Bacia do Atlântico no Instituto de Investigação Deltares, nos Países Baixos. P. DE MAAGT/ESA
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