The Mariana Trench is the deepest place on Earth.
IT’S 2550km long and up to 11,000m deep, and a lot remains unknown about the alien world that lies within the Mariana Trench.
Located off the coast of Guam in the western area of the North Pacific Ocean, the massive expanse of water is home to the Challenger Deep Trench, officially the deepest place on the planet and one that few people have ever been able to reach.
And now, in what’s been billed as a first, a team of researchers seeking to eavesdrop on the ocean floor have made a remarkable discovery in its depths.
The team of experts from the National Oceanic and Atmospheric Administration (NOAA), Oregon State University and the US Coast Guard had expected to hear very little when they plunged a titanium-encased hydrophone (an underwater microphone) to the bottom of the Challenger Deep for three weeks.
But instead of being greeted with a sea of silence they were shocked to find that both natural and man-made sounds permeated to the very bottom of the ocean.
Researchers deployed the hydrophone in an attempt to listen to ambient sound. Picture: US Coast Guard
“You would think that the deepest part of the ocean would be one of the quietest places on Earth,” NOAA research oceanographer and chief scientist on the project Robert Dziak said.
“Yet there really is almost constant noise from both natural and man-made sources. The ambient sound field at Challenger Deep is dominated by the sound of earthquakes, both near and far was well as the distinct moans of baleen whales and the overwhelming clamour of a category four typhoon that just happened to pass overhead.
They plunged the microphone into the depths of the ocean.
“There was also a lot of noise from ship traffic, identifiable by the clear sound pattern the ship propellers make when they pass by.
“Guam is very close to Challenger Deep and is a regional hub for container shipping with China and the Philippines.”
“It is akin to sending a deep-space probe to the outer solar system. We’re sending out a deep-ocean probe to the unknown reaches of inner space.”
HEAR THE SOUNDS HERE.
Life at the bottom of the Challenger Deep. Picture: Deepsea Challenge 3D
Getting those sounds was far from easy; the pressure at the bottom of the Challenger Deep trough is incredible, and engineers had to work to develop a microphone capable of withstanding the forces.
There are limited life forms down there, partly due to the extreme pressure at the bottom of the near-freezing trench — a crushing 16,000 pounds per square inch (7257 kilograms per 6.45 square centimetres) to be exact, which is similar to balancing a full bus on your big toe. Ouch!
“We had never put a hydrophone deeper than a mile (1.6km) or so below the surface, so putting an instrument down some seven miles into the ocean was daunting,” Oregon State ocean engineer Haru Matsumoto said.
“We had to drop the hydrophone mooring down through the water column at no more than about five metres per second. Structures don’t like rapid change and we were afraid we would crack the ceramic housing outside the hydrophone.”
The location of the Challenger Deep.Source:Supplied
For the past few months, the researchers have been analysing the sounds picked up by the instrument, and were so amazed that they plan to return in 2017 to deploy the hydrophone for a longer period of time.
“Sound doesn’t get as weak as you think it does even that far from the source,” Matsumoto said.
INTO THE DEEP
Explorer and director James Cameron is one of the few to have witnessed what lies beneath, having gone on a journey to the bottom of the Challenger Deep for his documentary Deepsea Challenge in 2014, ending up some 10,908 metres down.
Cameron (who directed Titanic and Avatar) is the only person to have reached the deepest known place on Earth since 1960, when Lieutenant Don Walsh and Jacques Piccard made their record-setting dive in the same area in the US Navy submersible Trieste.
Watch a clip from the National Geographic film "Deepsea Challenge 3D," starring James Cameron, Frank Lotito, and Lachlan Woods. Photo/Video:
Cameron carried out at series of dives in different locations in the lead-up to the feat, using a submersible vehicle custom built right here in Australia in a secret project. The construction cost a whopping $35,000 a day.
He described the feeling of venturing into the trench as “peaceful, lonely, getting further away from the world you came from”.
“There’s a purity,” he said. “A sense of the sacred, and a vastness of all we don’t know is felt. You feel like you dived deeper than limits of life itself.”
Touch down. Picture: Deepsea Challenge 3D
A total of 68 new species were identified from the sub, which was equipped with 3D cameras.
“The deeper we go, the smaller the life forms. It’s like the moon, it’s just unbelievable.”
The sea cucumber. Picture: Deepsea Challenge 3D
Saying that, life large enough to be seen with the naked eye does exist, ranging from cupcake-sized single-celled organisms (xenophyophores), many shrimp-like amphipods and an abundant holothurian (sea cucumber) that’s likely to represent a new species.
One thing’s for sure, it’s a fascinating place.
A sea anemone rides a crab, which was seen on the way down but not at the bottom. Picture: Deepsea Challenge 3D
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