Going beyond the Abyss
Image Source: http://www.sxc.hu/photo/929961
In March 2012, film director James Cameron became the first person to make a solo dive into the world's deepest part – the Challenger Deep within the Mariana Trench. Named after the ship that discovered it HMS Challenger, the Challenger Deep lies some 10,900m beneath the ocean – and what lies down there is largely a mystery to us.
How did he get there?
To imagine just how deep it is, picture the towering height of Mount Everest – and then add on five-and-a-half Petronas Twin Towers stacked from base to tip. Getting to such depths takes an amazing feat of engineering to cope with the extreme high pressure environment, which stand at 16,000 pounds per square inch. That's roughly three full vans resting on little more than a thumb.
The Challenger Deep was visited by humans once before. In 1960, Lt. Don Walsh of the US Navy and scientist Jacques Piccard sat in a 6.5ft-wide sphere within the Bathyscaphe Trieste, a 60-foot submersible that weighed about 51 tonnes. To help it descend, the Trieste was filled with floats loaded with 126,240 liters of fuel for buoyancy, along with nine tons of iron pellets to weigh it down. The journey to the bottom journey took 4 hours and 48 minutes. That feels like an eternity in such a small area.
In contrast, DCV1 is much lighter and faster, although not that much more comfortable inside. Designed by Cameron and Ron Allum from the Australia-based Acheron Project, the DCV1 is a 24ft-long craft that weighed just 11.8 tonnes, and carried with it 500kg of ballast weight that helped it descend. Unlike the boat-shaped Trieste, the DCV1 was designed like a torpedo for a more rapid descent, with Cameron needing just 2 hours and 36 minutes to reach the Challenger Deep.
Though it's been decades since the Trieste descended, comforts for the pilot within the DCV1 wasn't that much better. Cameron needed to cram his 6ft2in frame into a sphere measuring just 1.1m in diameter (he took up yoga to help), while the 2.5-inch steel walls around the sphere protected him from the immense pressures outside. The craft expedition was designed so that Cameron could spend up to six hours collecting samples and recording his journey in pitch darkness.
The biggest differences between the DCV1 and the Trieste is attributed to the material surrounding the submersible. About 70% of DCV1's volume comprised of a specially developed buoyancy syntactic foam, which is made of very small hollow glass spheres suspended in an epoxy resin. This made the craft able to withstand extreme pressures while providing buoyancy. Because of this foam, the DCV1 didn't need to carry the massive amount of petrol that the Trieste needed for buoyancy.
What did he find down there?
Among the reasons that drove Cameron to explore Challenger Deep was to find evidence of life – as reported by Walsh and Piccard during their dive in 1960. "We spotted a flatfish, like a small halibut, or sole, about a foot long, I guess," said Walsh. However there was no photographic evidence of this, and their view was obscured by a cloud of white sediment kicked up while at the bottom.
Cameron, however, didn't spot anything resembling a fish or any life more than an inch long. “The only free swimmers I saw were small amphipods"—shrimplike bottom-feeders that appear to be common across most marine environments,” he said in an interview with National Geographic.
During his 70-minute mission at the bottom, during which he collected muddy samples for analysis, Cameron witnessed an alien-like lunar surface that was devoid of life or features. “When I came to Challenger Deep, the bottom was completely featureless. I had this idea that life would adapt to the deep ... but I don't think we're seeing that,” he said.
Although finding large lifeforms at such depths may not be possible, there are lifeforms that can indeed survive extreme levels of pressure at the Abyssal Zone. Located at 13,120ft, bizarre and frightening-looking lifeforms like the Anglerfish, Fangtooth, and Flashlight Fish exist in total darkness (light stops penetrating at 3280ft) and live in pressures of 11,000 psi.
Life further down in the Hadal Zone, at 20,000ft, is rarer still. In 2010, a new species of archaebacteria, Pyrococcus CH1, was discovered thriving on a mid-Atlantic ridge within a temperature range of 80 to 105°C and able to divide itself up to a hydrostatic pressure of over 17,000psi.
If life is found at the Challenger Deep – even in microbial form – it would give a glimpse into how life could exist in such extreme – and even extraterrestrial – environments. Who knows what other secrets the deep oceans holds?
Very brave of him. It's a source of inspiration for all oceanographers.