Project Neptune: Undersea exploration

It’s a classic pub quiz question: how much of the Earth’s surface has been explored? Perhaps 95 per cent, or maybe 99 per cent? The answer is less than five per cent – much less in fact.

That’s because over 70 per cent of the Earth’s surface is covered by ocean. According to the US National Oceanic and Atmospheric Administration, over 95 per cent of the oceans remain unexplored. While humans have landed on the Moon six times, they have visited the deepest part of the ocean, the 11,000m Challenger Deep site at Mariana Trench in the western Pacific only once, in 1960.

As with space exploration, scientists are increasingly turning to robots and remote sensing to find out more about what lies beneath the waves. And the most ambitious effort so far is now underway 2.6km below the surface of the north-eastern Pacific. Called Neptune Canada, the £100 million project aims to continuously monitor conditions on the seabed off the coast of Vancouver Island for the next 25 years. To do so, researchers have wired together an 800km-long array of sensors, cameras and seismometers, plus an undersea robot called Wally.

Each week, the array transmits around a terabyte of information (a million million bytes) about conditions on the seabed, giving scientists unprecedented insights into what’s happening down there. When the devastating 8.8 Richter earthquake struck the coast of Chile in February, Neptune Canada’s sensors 11,000km away detected the passage of a small tsunami.

The detection of such long-range disturbances is of more than academic interest. Scientists have discovered huge reservoirs of methane gas trapped in deposits on the seabed. If disturbed, these could release vast amounts of this potent greenhouse gas, boosting global warming.

One of the targets of Wally the robot is to explore methane deposits off Vancouver, and see how they respond to disturbances. “The ocean is the engine of the planet so it affects us all,” explains Dr Mairi Best of the University of Victoria. “This project gives us the capacity to understand events we simply have no way to capture by going out in ships. Now we’re there all the time.”

Image courtesy of NOAA

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