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An autonomous, uncrewed vehicle sets out to map the ocean floor

An autonomous, uncrewed vehicle sets out to map the ocean floor
30 Sep
2021
The Saildrone Surveyor, a type of uncrewed autonomous vehicle, has completed its maiden voyage. Its design could enable Saildrone to revolutionise ocean mapping

The search for the missing Malaysian Airlines Flight 370 in March 2014 amassed a monumental bill – US$56 million, to be precise. With no sign of the aircraft on 5 May, officials from Australia, Malaysia and China announced that, to better plan the stages of the search effort, a ‘detailed oceanographic mapping of the search area’ would be conducted. A Chinese survey vessel later charted 208,000 square kilometres of the Indian Ocean seabed, at great cost. That effort might not have been necessary had a detailed map of the ocean floor already existed, believes Brian Connon, vice president of ocean mapping at Saildrone – a company pioneering new, nimbler methods to map the seabed.

Saildrone’s autonomous, uncrewed surface vehicle – the Saildrone Surveyor – arrived in Hawaii in July after a 2,250-nautical-mile voyage from San Francisco. After 28 days at sea, the Surveyor mapped 6,400 square nautical miles of seafloor, running mostly on renewable energy. The vehicle’s data will contribute to Seabed 2030’s mission – a collaboration between the Nippon Foundation and GEBCO – to complete a map of the world’s ocean floor by 2030.

The company’s fleet of uncrewed vehicles aims to fill a void in our oceanic knowledge: just 20 per cent of the world’s ocean seafloor has been mapped, which stymies our understanding of the ocean system, geology and meteorology. ‘From a scientific perspective, we need to know the topography of the ocean floor to improve our models. Ultimately, we can’t use information we don’t have,’ says Connon. ‘Whether it’s for aquaculture, marine protected areas, seabed mining, or search parties for missing airlines or Second World War warheads, every ocean project can be improved with a knowledge of what’s on the seabed.’

But it’s no small task. It’s easier to map distant planets than it is to map the seafloor, Connon explains. ‘There are only certain technologies that can be used, and all of them have limitations,’ he says. Electromagnetic waves, such as light and radar, are highly attenuated in ocean water. Optical and electromagnetic sensors used to measure topography on land can’t penetrate more than tens of metres in ocean water. Some techniques provide a coarse view. ‘You can use an aircraft with a laser bathymetry system; it shoots a laser that reflects from the surface of the water and from the bottom, and the time difference can tell you how deep the water is. But that’s only if the water is clear, so you can only get to 30–40 metres depth at best.’

Saildrone 2The Saildrone Surveyor approaches the Golden Gate Bridge

Other techniques, including acoustic/sonar systems, lose resolution in deep water. The autonomous underwater vehicles that harbour them need specialised ships for deployment and support, and their navigation systems lose sensitivity as the mission goes on.

There have also been logistical inefficiencies. ‘To get to remote parts intensive,’ explains Connon. ‘People have to get back to shore to get new food, offload waste and refuel.’ The autonomous Saildrone Surveyor eschews the weight of a crew and harvests renewable energy from its surroundings. It has solar panels and hydrogenerators that propel it as it moves through the water. In good wind, the Surveyor simply sails to extend its endurance. Without the noise of the crew and heavy electric generators, the topographical and bathymetric data it generates are the cleanest achieved so far. ‘We’ve now got an environmentally friendly, lowcarbon solution that can stay out and map the seabed at high quality for months at a time.’

With the proof-of-concept voyage now completed, Saildrone is already receiving huge commercial interest from developers – including renewable energy companies and national governments – to scale up its fleet. More vehicles will provide greater coverage for the Seabed 2030 goal. Saildrone also envisages a future where its autonomous vehicles, roaming the waters with on-board cameras and machine learning systems, will be able to detect signs of illegal fishing in marine protected areas. A smart map of the ocean floor may not be so far off.

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