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  • This episode was brought to you by Music for Scientists

  • now available on all streaming services.

  • [♩INTRO]

  • The ocean covers over 70% of our planet, with an average water depth

  • of 3500 meters, making it the largest ecosystem on Earth.

  • It's so huge, and so sparsely-explored, that it's often referred to as inner space.

  • There are several challenges to exploring the ocean -- like the need to bring air.

  • But pressure is where the ocean exploration can get really dangerous.

  • Under water, every 10 meters of depth adds another atmosphere's worth

  • of pressure, compared to sea level

  • quickly going from just a little squeeze to bone-crushing.

  • Still, these immense pressures haven't stopped us from trying to reach the

  • greatest depths possible, to learn as much as we can about inner space.

  • And it's not easy -- but here are five ways we can do it.

  • Recreational SCUBA divers are warned not to dive deeper than 40 meters.

  • That's because the compressed gases they carry for breathing underwater

  • can become dangerous at higher pressures.

  • During deeper dives, the added water pressure increases the amount of oxygen

  • and nitrogen delivered to a diver every time they take a breath.

  • And exposure to higher than normal concentrations of those gases

  • can have a toxic effect on the diver's body.

  • Oxygen toxicity due to high oxygen concentrations can cause seizures,

  • lung failure, and even death.

  • And nitrogen narcosis from too much nitrogen

  • can cause a diver to feel disoriented or even lose consciousness.

  • As you can imagine, both of these conditions

  • would be dangerous while exploring underwater.

  • So, to prevent them from happening,

  • deep water divers breathe trimix gases instead.

  • This is a blend of three gases, usually oxygen, nitrogen, and helium.

  • This blend reduces the amount of oxygen and nitrogen in the breathing mix

  • and keeps them from reaching toxic concentrations, even at higher pressures.

  • Trimix gases expand the depth limit to 60 meters or more,

  • depending on how experienced the diver is.

  • And the use of trimix gases in scientific diving has helped researchers explore

  • the twilight zone of the ocean, a zone that extends from 60 to 150 meters deep.

  • This zone is too shallow to justify the costs of exploration

  • with expensive technology like submersibles,

  • so it's one of the most unexplored regions of the ocean.

  • Divers exploring the twilight zone are discovering up to 10 new species per hour!

  • Trimix gases are also often used in conjunction with a rebreather:

  • a device that absorbs the carbon dioxide exhaled by the diver,

  • allowing them to rebreathe the unused oxygen and inert gases from each breath.

  • These are different from traditional SCUBA regulators,

  • where the exhaled gas gets released as bubbles directly into the water.

  • Rebreathers extend the life of a limited supply of gas,

  • as well as eliminate all bubbles

  • which happens to provide an extra benefit for researchers

  • attempting to observe particularly skittish creatures.

  • Next are atmospheric diving suits, which are quite a bit like space suits.

  • There are other ways to explore the deep ocean, but if you want to use your own

  • arms and legs to interact with the environment, this is really the only option.

  • These things are more like wearable submersibles than anything else,

  • and can be a bit clunky and hard to maneuver in

  • perhaps even more so than a space suit, in fact.

  • Still, the wearer can descend to depths of over 700 meters for several hours,

  • with none of the dangers that come from SCUBA diving.

  • The suits are able to keep their interior pressure at atmospheric levels,

  • as well as provide several hours of air supply,

  • so the wearer doesn't even need to be SCUBA certified.

  • They're also a fantastic way to explore the deeper marine environment

  • without a lot of loud noise coming from engines, like on a submarine

  • again, making things easier for skittish wildlife.

  • Now, while they may resemble space suits,

  • these were some of the earliest technologies used

  • to explore marine environments for more than a few minutes at a time.

  • The first one was developed in 1715!

  • The most recent iteration of this suit is called the Exosuit,

  • which researchers want to use to study bioluminescence and biofluorescence

  • at depths of 200 to 1000 meters.

  • Many migrating fish, plankton, and other animals living in this depth range

  • have these glowy properties, but scientists have only been able to study them

  • with remote instruments or from samples found in trawl nets.

  • The pressure at these depths can be 30 times greater than at the surface,

  • and even the most experienced diver cannot safely explore in this zone.

  • Putting a researcher down safely at that depth, with no engine noise,

  • would be a huge opportunity to learn more about this part of inner space.

  • Bathyscaphes, at first glance, look a lot like a submarine.

  • But they have no way to be maneuvered in the water,

  • so they're more like an underwater hot air balloon than anything else.

  • A bathyscaphe has a huge tank filled with gasoline to give it buoyancy.

  • That's because gasoline is both lightweight and resists being compressed,

  • even at huge depths.

  • To descend, the bathyscaphe is loaded up with enough iron shot

  • to help it slowly sink down to the depths.

  • To ascend, that shot is released on the ocean floor,

  • and the bathyscaphe floats to the top with the help of its gasoline-filled tank.

  • This seems pretty simple compared to the fancier technologies available today

  • but a bathyscaphe is what took humans to the deepest spot on our planet

  • for the first time.

  • In 1960, the Trieste successfully went all the way to the bottom

  • of the Challenger Deep in the Mariana Trench,

  • which is just over 11,000 meters deep.

  • The two men on board were able to observe for the first time

  • that there was life even all the way down there.

  • This observation lasted less than 20 minutes before they had to head back

  • to the surface, thanks to a crack in one of the viewing windows.

  • But in that short time span, they saw shrimp, fish, and lots of bioluminescence.

  • Bathyscaphes are no longer in use today, because the gasoline tanks

  • could rupture and fill with water,

  • which would send the vessel to the bottom with no way to reach the surface.

  • But the success of the Trieste paved the way for future exploration attempts

  • to reach the Challenger Deep, although none were successful until 2012

  • and it was a submarine that successfully made that journey.

  • Submarines have allowed humans to visit depths

  • much greater than we ever thought possible.

  • Deep submergence vehicles, or DSVs,

  • can take people to the deepest depths of the ocean.

  • And they have to be made of special materials

  • to withstand the immense pressure.

  • Surprisingly, the main material they're made of isn't a metal like titanium,

  • but rather a material called syntactic foam.

  • This special foam is made out of millions of teeny-tiny hollow glass spheres

  • suspended in an epoxy resin, and it can withstand crushing pressures

  • while also providing the DSV with enough buoyancy to float back to the surface.

  • The DSV known as DeepSea Challenger was designed specifically

  • to take film director James Cameron to the Challenger Deep.

  • 70 percent of this submersible was made of a syntactic foam

  • specifically designed to withstand the pressures of Challenger Deep,

  • which are over 1000 times the pressure that we experience on land.

  • And generally, not only can submarines travel to great depths,

  • but they're also equipped with a whole suite of technologies

  • to help researchers better understand the deep sea environment.

  • They have robotic arms and storage boxes to collect samples,

  • high definition cameras, and a lot of lights

  • to light up the depths of the deep sea.

  • Early exploration with submarines blew the lid off of our current understanding

  • of what's down there.

  • Thanks to a DSV named ALVIN, researchers in the 1970s discovered

  • hydrothermal vents, as well as animals that thrive around them.

  • This led to the discovery of ecosystems that survive via chemosynthesis,

  • a way for organisms to produce energy using inorganic materials

  • rather than sunlight.

  • Some researchers believe these vents may be where life itself originated

  • at the bottom of the ocean, where the sunlight never reaches.

  • And by the way, ALVIN is still at it

  • after a decades-long career and tons of upgrades,

  • this funky little submarine is still helping us explore.

  • Finally, there is a way to get around the technical limitations of sending humans

  • to the bottom of the sea.

  • And it involvesnot sending humans.

  • Remotely operated vehicles, better known as ROVs

  • are like the Mars rovers of Earth.

  • They're an extremely valuable piece of technology for exploring inner space,

  • in part because they give researchers more time to explore.

  • ROVs have all the capabilities of a submersible

  • except the ability to hold people.

  • They have robotic arms and storage boxes for sample collection,

  • 4K cameras that capture tons of detail,

  • and enough lights to light up a football field.

  • They can travel to the deepest parts of the ocean

  • like, several ROVs visited the bottom of Challenger Deep

  • before a submarine successfully made the journey.

  • ROVs are generally operated from a ship at the ocean's surface,

  • connected to it by a series of cables.

  • These do things like send a live video feed back to researchers onboard the ship,

  • and provide a source of power.

  • Which means researchers aren't limited by batteries

  • or the need to use the restroom!

  • And even though ROVs are comparable to probes we've sent to space,

  • they have the distinct advantage of being a little closer to home

  • so they can be brought in for maintenance, for example.

  • This means endless observation opportunities,

  • giving scientists the unique ability to experience the deep sea for what it is.

  • An ROV was used to discover the wreck of the Titanic in 1985.

  • And since then, we've been using them to discover a number of other shipwrecks,

  • as well as justsee what's out there.

  • And lest you think scientists are keeping all this cool stuff for themselves,

  • you should know it's actually possible to livestream from ROVs.

  • Which is making inner space more accessible to everyone!

  • Exploring the depths of our ocean isn't easy.

  • But it's worth learning more about inner space -- our planet's biggest ecosystem.

  • We're discovering new things every time we send a piece of technology

  • into the ocean -- whether it's a diver, a submarine, or an ROV.

  • So, who knows what we will find next, way down there in inner space?

  • Whatever it is, the right soundtrack is waiting.

  • Music for Scientists is an album inspired by the beauty and truth of science,

  • as it expands our view of the world.

  • It celebrates the idea that even the most remote parts of our universe,

  • like the deep ocean, are ultimately knowable.

  • It also celebrates the scientists who create that knowledge

  • and share it with the rest of us.

  • After all, the human condition is all about knowing

  • about grasping towards and expanding the limits of our world and of ourselves.

  • If you think you'd enjoy Music for Scientists,

  • you can stream the album on all major services

  • or click the link below to catch the music video forFor Your Love”.

  • [♩OUTRO]

This episode was brought to you by Music for Scientists

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