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Satellites can spot toxic algae before it kills your dog

Karin Schenck hopes she can save the dog.

Schenck, a geographer specializing in remote sensing, works for EOMAP, a company spun out of the German Space Agency that uses satellite data to track water quality. For a decade, she has been using data collected by orbiting satellites to look beneath the surface of bodies of water for signs of life.

The life she seeks can be deadly: the microscopic aquatic plants and animals that make up colorful algal blooms. The loss of fertilizers and sewage, the increase in carbon dioxide in the atmosphere, and rising temperatures due to climate change have caused these blooms to appear more frequently in recent decades. Worse yet, they can be poisonous.

In the recent past, Schenk has relied on government-built satellites such as Landsat in the US and Sentinel in Europe to provide medium-resolution images of a place on Earth. about eight days. But now, she has access to daily high-resolution images from private companies.

While testing her company’s products in Lake Constance, Germany, she found evidence of algal blooms. But while waiting for an actual sample to be tested, a dog drank some water at the beach, got sick, and died.

“The authorities closed the baths, but it was too late,” she told Quartz.

Finding the science behind toxic algae

EOMAP works with local water agencies and municipalities around the world to monitor beaches and reservoirs. Before satellite monitoring, water quality could only be determined by sampling and observation. This makes tracking potentially toxic algae time-consuming and restricting it to specific areas. Detecting it using sensors in space could provide a more comprehensive and timely view of the situation.

To find these flowers, satellites detect reflected electromagnetic energy that cannot be seen by the human eye. It’s especially tricky in the case of water, because it reflects most of the light the satellites want to detect. The researchers examined green and red light bands, allowing them to detect chlorophyll, the chemical plants use for photosynthesis. In the past, data for these bands of light was only available from government satellites, but now more advanced private satellites are adding them.


Visualization showing the likelihood of harmful algae detected from space in German lakes.

US space data company Planet will start launching satellites in 2021 to capture eight-band spectral data. Now, In addition to the red, blue, green, and near-infrared spectra, Planet users can also get data from bands known as “red edge” and “coastal blue,” as well as yellow and green bands that don’t have interesting names. Jim Thomason, Planet’s vice president of product, said customers can use the data at a resolution of 3 meters per pixel, compared to Landsat’s 30 meters, and if the clouds cooperate, it can be viewed daily.

Schenck says this is “time resolution”, It’s an artistic term that denotes the frequency of images. The data collected, combined with finer spectral detail, allows EOMAP to create digital products that can alert water regulators to dangerous situations faster than they do today. Currently, the company monitors water resources around the world, and even in California, Lake Ellis Knoll, a popular recreational destination, is now suffering from algal blooms.

The future of spot water monitoring

Algal blooms aren’t the only aquatic phenomenon that’s causing problems. In the Atlantic, blooms of sargassum (a floating seaweed) have become more common and are now found throughout the Caribbean. Scientists suspect this has something to do with the effects of global warming on ocean temperatures and currents. The result can be piles of seaweed on beaches, which can harm tourism, create unpleasant odors, and even block boat traffic in ports.

SargAssure, a project supported by the UK Space Agency in partnership with universities in the UK and Mexico, uses Planet’s data to create a dashboard that municipalities or local businesses can use to Track Sargasso. Jeff Smith, an Earth observation consultant, said the company’s rapid data allows users to deploy measures ranging from floating arms to cleanup crews. Some companies are even trying to use seaweed as an ingredient.


SargAssure visualization of Sargassum off the coast of Mexico.

While Smith and Schenk applaud the rest of Planet’s bands, both are eagerly waiting A more productive source of data, called hyperspectral sensing. As the name suggests, such sensors collect data across a wider range of the electromagnetic spectrum, providing more information about detections. Planet plans to deploy such sensors in the future, while startup Pixxel launched its first hyperspectral sensor into space earlier this year, and another company, HyspecIQ, plans to launch its own satellite in 2023.



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