Several ongoing projects are trying to detect plastic pollution in oceans by using Space technology
The ocean is where life began. It is home to the majority of the Earth’s plants and animals. However, there is currently another habitant endangering all species living under and above water. Humans included. The habitant is called “Plastic”. Plastic’s largest market is packaging designed for immediate disposal (Sigogneau-Russell, 2003).
Scott Belcher, Ph.D., a research professor at the North Carolina State said “Chemicals from plastics are a constant part of our daily diet. We generally assume the water bottle holding that pure spring water, the microwave-safe plastic bowl we prepare our meals in, or the styrofoam cup holding a hot drink is there protecting our food and drinks. Rather than acting as a completely inert barrier, these plastics are breaking down and leaching chemicals, including endocrine-disrupting plasticizers like BPA or phthalates, flame retardants, and even toxic heavy metals that are all absorbed into our diets and bodies.”
“Although it is evident that humans are exposed to microplastics through their diet, and the presence of microplastics in seafood could pose a threat to food safety (Van Cauwenberghe and Janssen 2014, Bouwmeester et al. 2015), our understanding of the fate and toxicity of microplastics in humans constitutes a major knowledge gap” (Kershaw, 2016).
Due to weathering plastic debris renders into small particle sizes that even small marine invertebrates may ingest. (Rougier, 2014). Hence, it is untraceable to its source and enormously difficult to remove from open ocean environments (Jambeck, 2015).
Monitoring marine litter by satellites could give researchers data about the abundance, its concentrations and movement. Paolo Corradi, an engineer with the European Space Agency said (2018): “In particular, plastic has specific infrared fingerprints that are sometimes used in the recycling industry to sort plastic items from other refuse on a conveyor belt.”
Currently there are several projects in development stage, which aim at monitoring the plastic disposal crisis. The European Space Agency funded a project called “OptiMAL” (Optical methods for Marine Litter detection), which is aiming to detect microplastics (with a diameter < 5 mm) on or near the surface of the ocean as well as larger pieces of plastic along shorelines (Berger, “Newsdeeply”). The distribution of microplastics in the oceans has been described using various ocean circulation models, highlighting major discrepancies in their predictions. Using different protocols by agencies and citizens, the accumulation of plastics on shore were monitored (International Marine Debris Conference, 2018).
Paolo Corradi stated (2018): “For now, the goal is to demonstrate the feasibility of remote sensing of plastic litter with satellites. Eventually, the scientists would like to be able to provide data that could produce a map of global concentrations of the plastic debris”.
According the plan of project “OptiMAL”, scientists will collect the spectral signals of plastic at sea for different types of material in various states of degradation and concentrations. Afterwards the signals will be entered into computer models that would simulate how those signals would look through the atmosphere, indicating whether it’s possible for a satellite orbiting the Earth to detect those signals and, if so, how (Berger, “Newsdeeply”).
If the signals are strong enough to be able to detect plastics, researchers can develop algorithms that might be able to track down and quantify concentrations of plastic litter. If this attempt is successful, it would break new ground in the fight against plastic pollution, since it will have a significant impact in addressing fundamental scientific questions. Furthermore, it will provide tools for environmental monitoring for the benefit of the society.
“OptiMAL” is not the only ongoing project in this field. Marcus Eriksen, cofounder of the 5 Gyres Institute, says he has seen other efforts to aerially monitor ocean plastic pollution, such as aerial inspections conducted by a plane or drone, which typically focus on a single region.
Another project of the European Space Agency is called “RESMALI” (The Remote Sensing of Marine Litter). It focuses on a feasibility study for a mission concept devoted to remotely sense ocean plastics using satellites as platforms. Both “natural” as well as “artificial” marine litter samples with various ranges of size that are classified by their composition are being used to run simulations. Simulations aid to find out thresholds values for marine litter and “Top of Atmosphere” (TOA) Reflectance level, for a potential passive hyperspectral radiometric instrument which also includes, but is not limited to, optimal altitude, spectral sensitivity, and instrumental viewing angle (International Marine Debris Conference, 2018).
With rising population and increased overall per capita consumption associated with economic growth, especially in urban areas and developing African countries, our waste will continue to grow. A long-term solution is definitely the reduction of waste. The current plastic pollution of marine ecosystems is endangering a great number of species, probably humans included. Wilson (2012) argues, we will not reach a global “peak waste” before 2100. Therefore, immediate action needs to be taken to combat plastic pollution. Space technology can serve as a basis for informed decision making and policies against the plastic pollution of the oceans. It can as well serve as an information base for cleaning initiatives. However, only targeted action against litter disposal in the oceans can prevent the oceans from being the place where life ended.