Our marine habitats are under serious threat from pollution. To help monitor, restrict and reduce this damage, organisations around the world are increasingly turning to satellite imagery.
An estimated 41% of our oceans are adversely impacted by human activity on land. A significant portion of the waste we create ends up flowing into the ocean, including eight million tonnes of plastic each year – the same as 57,000 blue whales. Plastic debris is thought to kill more than one million seabirds and 100,000 marine mammals each year. Whether by accident or design, humans are also responsible for adding other garbage, oil and toxic waste to the ocean.
Satellite Image of Oil Rig Explosion in the Gulf of Mexico
The ocean is the least monitored area on the planet. With increased pollution and damage to marine habitats, there is a growing need to better monitor this vast area of the Earth’s surface. The role of Earth observation is becoming increasingly valuable, offering effective global insight and providing detailed very high-resolution satellite imagery to support current monitoring efforts from traditional flying platforms and patrol vessels.
- Florian Thirion, Maritime Marketing Manager, Communication, Intelligence & Security at Airbus
The need to actively reduce the causes and consequences of marine pollution has never been greater – a message spread by events like World Cleanup Day on 21 September (see below for more details). But to manage the problem, we need to know exactly what we’re dealing with.
Earth observation satellites, which normally operate between 200 and 1,000 kilometres above the Earth, are proving increasingly valuable. They can detect changes in sea state, ocean colour, temperature and reflectance caused by objects in the water. This information helps governments, researchers and environmental organisations detect and monitor areas of pollution and work out how to combat them.
How satellites detect ocean pollution
Earth observation satellites are able to capture images of huge areas multiple times a day, ranging from a few hundred square kilometres to more than 50,000. The quality of image data across an area remains consistent.
That data falls into two categories – optical and radar. Optical satellites produce imagery similar to a classic photograph – as the human eye sees the world. As such, they can only produce images under the right light and weather conditions. Radar satellite imagery, however, can produce images day or night in almost any weather.
So, what can they see? Airbus’ TerraSAR-X radar satellite can capture images with resolutions of up to 40 metres, making it ideal for detecting objects across large areas and highlighting changes in surface patterns – an oil spill, for example. The company’s Pléiades constellation of optical satellites have a resolution of 50 centimetres – one pixel for every half a metre – but cover a smaller area. That makes them good at identifying specific boats or objects previously detected by a radar satellite.
The images are used by a variety of organisations, from the European Space Agency (ESA) to coastguard authorities and the United Nations. In the last couple of years, Airbus satellites have helped to detect and monitor oil spills, shipwrecks and toxic gulf weed in the Caribbean.
The company also provides imagery to Waste Free Oceans, which collects and transforms ocean waste into new, innovative products like emergency shelters, educational material and furniture. And it is partnering with The Ocean Cleanup, a Dutch-based company looking to deploy floating garbage collectors many of hundreds of metres long.
New technology for easier detection
Detecting plastic isn’t easy. Ocean waste patches are mostly made up of tiny pieces too small for satellites to detect. ESA is funding research that uses the Airbus-built Sentinel-2 satellites in an attempt to solve the issue. Because plastic has a different light signature to vegetation, scientists are developing an index to analyse each pixel of a satellite image. By refining the approach and using machine learning, it hopes to build up a clearer picture of marine plastic pollution.
Airbus is also working on new solutions to the problem. In 2020, it will launch the first satellites in its Pléiades Neo constellation, capable of delivering images with a resolution of 30 centimetres. Zephyr, the company’s high-altitude pseudo-satellite, will soon be able to provide additional local image support from its position in the stratosphere, 20 kilometres above the Earth.
Another valuable method of detection is on the water itself. A new smartphone app under development will enable ocean users to report areas of pollution. Satellite imagery will attempt to verify the sightings, before alerting the appropriate authorities.
World clean up day
One of the largest civic movements of our time, World Cleanup Day unites more than 150 countries across the globe. On 21 September 2019, an estimated 18 million volunteers and partners will spend 36 hours cleaning up litter and waste from our beaches, rivers, forests, and streets.