Every year, about eight million tons of plastic enters the oceans. To combat this, a bright ideain 2013 Boyan Slat who was then 18 found a solution to rid the oceans of excess rubbish by a passive network of floating barriers that concentrate floating plastic using existing ocean currents.

In preparation for full deployment in 2020, The Ocean Cleanup in the summer of 2015 organised the Mega Expedition, in which 30 vessels crossed the Great Pacific Garbage Patch simultaneously to produce the first high-resolution map of the plastic pollution problem.

To deliver this, LiDAR experts Teledyne Optech partnered with The Ocean Cleanup in their Aerial Expedition research mission. Teledyne Optech announced their CZMIL (Coastal Zone Mapping and Imaging LiDAR) has successfully carried out the first in a series of low-speed, low-altitude survey flights across the Great Pacific Garbage Patch.

The initial findings show that much of the trash accumulates in five ocean garbage patches, the largest located between Hawaii and California. Plastic in these garbage patches over time breaks down into tiny plastic particles that can be eaten by fish and birds, thereby entering the food chain.

Part of the objects in the Patch are underwater, so the Optech CZMIL’s depth-penetration capability was crucial for surveying. Image: The Ocean Cleanup

The Ocean Cleanup’s Aerial Expedition uses a combination of experienced human observers and advanced sensors to count the debris in the Great Pacific Garbage Patch, with a focus on the presence of so-called ghost nets. The sensors will also be used to convert this count to a weight estimate by registering the size of the found objects. In the case of ghost nets, a substantial part of the net will float underwater. To properly measure how far the plastic reaches under the surface, The Ocean Cleanup project used the CZMIL’s green LiDAR, which can detect objects to depths of tens of meters.

As part of The Ocean Cleanup’s Aerial Expedition, the CZMIL surveyed hundreds of square kilometers of the Patch aboard a C-130 Hercules aircraft. Its Optech HydroFusion software suite will combine this LiDAR data with information from the CZMIL’s RGB camera and an ITRES SASI-600 short-wave infrared sensor to create the first 3D visualisation of the patch and help identify the number, size and type of plastic objects present.

“We wanted state-of-the-art sensor technology to supplement the visual observations of our survey team with the data from our Mega Expedition, and to finalise the first detailed plastic data map of the Great Pacific Garbage Patch,” said Boyan Slat, CEO and founder of The Ocean Cleanup. “In Teledyne Optech we found exactly that partnership, which is helping us to get another step closer to get to the largest cleanup in history.”