Cameron’s Deepsea Challenge ‘harder than the moon’

“When explorers go to hostile realms – space or sea – we live or die by our machines,” James Cameron said in his final tweet as he began his voyage to the bottom of the ocean in the Deepsea Challenger.

His destination, Challenger Deep, the deepest point on earth, in the Mariana Trench, was one of the least explored – and hence exciting – places known to man.

But it is also one of the most dangerous. That, oceanographers say, is the main reason that there has been more people go to the moon than to the depths of the sea.

“A fault in the vessel would be worse than Apollo 13,” Dr Simon Boxall, at the National Oceanography Centre, University of Southampton, told Channel 4 News. “Because you have no time to deal with it.”

The largest problem facing engineers constructing the Challenger was less conceptual, but more mechanical: how to build a vessel which would withstand the overwhelming pressure at that depth.

Deeper than Everest

Our ears will feel pain at eight feet below water levels; Cameron was planning to plumb to depths of more than 36,000 feet – deeper than Everest is tall.

Around 200 metres below sea level will kill you, Dr Boxall said, as the body would be crushed to death. The pressure at the depths to which Cameron intended to dive is seven to eight tonnes per square inch – enough to dissolve human bones in the water because calcium is unstable at such depths.

“A fault in the vessel would be worse than Apollo 13.” Dr Simon Boxall, National Oceanography Centre

“The pressure James Cameron was at is the equivalent of a London taxi being balanced on the end of your finger,” Dr Boxall said. “What needed to be done is to maintain atmospheric pressure inside the vessel throughout. It would be like being inside a great, big glass sphere, at atmospheric pressure, which is stopping water from coming inside.”

But a single hairline fracture would have been enough to kill Cameron almost instantly, Dr Boxall said. “Water would leak in, and you would get the same pressure inside as outside the vessel. Everything would be crushed within about half a second.”

To compound their difficulties, engineers would have very little means by which they could test their vessel.

“There are no chambers big enough to test it, so you’re relying on maths, physics, and a tremendous account of finger-crossing,” Dr Boxall said. “You can’t do a dry run with someone in it. James Cameron was the guinea pig. Fortunately, it worked, or we would have lost a film director.”

Inspiration

The Deepsea Challenger was created secretly in Australia by scientists from the Scripps Institution of Oceanography, Jet Propulsion Laboratory and the University of Hawaii – a 24 foot, 12 tonne hulk of steel with walls 2.5 inches thick.

Inside the pressurised compartment, it was so cramped – in order to keep it as small as possible – that Cameron could barely move his arms or legs. An oxygen supply would be needed for him to be able to breathe.

“That would be another problem,” Dr Boxall said. “It would get very hot in there, and it would be very cramped. And the journey down there is quite long.”

It would get very hot in there, and it would be very cramped. And the journey down there is quite long. Dr Simon Boxall

Steel weights dragged it to the bottom. To resurface, the weights’ electromagnetic grip was broken with the flick of a switch. The deep-diving submersible shot back to the surface of the water, breaking through the waves early this morning.

Cameron was not the first to dive down to those depths; US Navy Captain, Don Walsh, 80, and Swiss oceanographer, Jacques Piccard, who died four years ago, were the first and last before him to reach the bottom of the Mariana Trench in 1960.

“It’s a huge feat of engineering,” Dr Boxall said. “That’s why more people have been to the moon. But to accomplish that 50 years ago, when we didn’t have the technology we have now, is astounding.”

But the bigger benefit, he added, was the inspiration to explore, learn and challenge human knowledge.

“We have to ask whether we gain anything from [these expeditions]. Is it worth people risking their lives, when we can get the same results [in terms of scientific knowledge] by sending something down, or someone not as deep.

“But it’s about inspiring young people into science, and understanding the ocean. We only know about 20 per cent of the ocean floor, and that’s what’s behind the ocean’s appeal.”