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Ep353: Challenger Deep · Kidcast Daily

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  Spin the wheel, let's take a ride.
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  Sports and science bursting from inside a world of wonder.
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  Open wide. Come on kids, let's amplify kid
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  caps. Daily starts your day.
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  Fun and laughter come your way. Sports and trivia games galore.
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  Welcome to Kick Ass Daily where we bring you news, trivia, fun
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  facts and more made just for curious kids like you.
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  Today we are heading to the deepest known point in Earths
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  oceans. It is called Challenger Deep and
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  it sits at the very bottom of the Mariana Trench in the
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  western Pacific Ocean. If you looked at a map, you
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  would find it east of the Philippines and South of Japan.
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  Scientists measure its depth at roughly 10,900 to nearly 11,000
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  meters below the surface. That is almost 11 kilometers
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  straight down. At that depth there is no
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  sunlight, the water is very cold and the pressure is extreme.
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  Let's break down what that all means.
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  Near the surface, you feel normal air pressure.
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  As you go down in the ocean, the weight of the water above you
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  adds more and more pressure. At the bottom of Challenger
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  Deep, the pressure is more than 1000 times the air pressure you
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  feel at sea level. That much pressure can crush
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  many materials. Because of this, scientists and
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  engineers build special vehicles with strong, rounded holes,
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  careful seals and parts that will not collapse.
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  The temperature near the bottom is close to freezing, usually
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  just a few degrees above 0°C. With no sunlight and very little
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  heat, it is a dark, cold place. So how did Challenger Deep get
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  its name? In the 1870s, a British ship
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  named HMS Challenger sailed around the world to study the
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  oceans. The crew used ropes and weights
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  to measure ocean depths. Their work helped discover the
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  deep trench system in the Pacific, and the deepest spot
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  was later named Challenger Deep in honor of that ship's mission.
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  Later technology improved sonar systems, sent sound waves into
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  the water and timed how fast they returned to measure depth
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  more accurately. People have reached the bottom,
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  but only a few times. In 1960, two explorers, Jacques
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  Picar and Don Walsh, descended in a bath escape called Trieste.
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  It had a pressure resistant sphere for the crew and a large
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  float on top that provided lift. Their dive took hours, and they
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  stayed at the bottom for a short time before returning to the
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  surface. In 2012, filmmaker and explorer
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  James Cameron made a solo dive in a submersible built for the
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  mission. In recent years, explorer Victor
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  Viscovo and other teams have made multiple dives using a
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  modern sub called Limiting Factor, allowing repeat visits
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  and detailed surveys. Robotic Landers have also gone
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  down to record video, measure chemistry and collect samples.
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  What is life like at this depth? Even here, there is life.
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  Scientists have seen small crustaceans called amphipods,
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  sea cucumbers called holotherians, and many kinds of
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  microbes. These organisms survive with
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  special adaptations that keep their cells and enzymes working
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  under high pressure. Food is limited, so many
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  creatures feed on organic particles that drift down from
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  the upper ocean. Microbes can also use chemicals
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  in the sediments and water to get energy.
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  These discoveries show that life can persist in very tough
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  conditions as long as there is a source of energy and the right
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  chemistry. Now let's dig into how
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  scientists study such an reachable place.
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  Crude submersibles are built from thick metal or ceramic
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  spheres that resist pressure. Windows are made from special
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  layers of transparent material. Robotic Landers are designed to
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  sink straight down, sit on the sea floor and release weights to
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  float back up. Instruments include cameras that
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  can handle darkness, lights that do not overheat and sensors that
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  measure pressure, temperature, salinity and oxygen.
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  Some Landers leave traps with bait to collect animals.
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  Others push small tubes into the mud to bring up cores for study.
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  After a dive, teams examine videos, identify species, and
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  analyze the chemistry of water and sediments.
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  Here is a trivia question for you.
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  Which color of visible light travels the farthest underwater?
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  The answer is blue water absorbs red, orange, and yellow light
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  more quickly, so blue light can reach deeper.
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  At the depth of Challenger Deep, though, even blue light from the
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  sun does not reach any light. There comes from submersible
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  lamps or tiny flashes made by some organisms that produce
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  their own light. The shape of the sea floor in
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  the trench is also interesting. Challenger Deep has several
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  small basins separated by ridges.
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  The trench itself exists because one tectonic plate is sliding
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  under another in a process called subduction.
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  This motion forms deep valleys in the ocean floor.
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  Scientists map the area with multi beam sonar from ships and
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  with sonar units on submersibles.
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  These maps help pilots land safely and help researchers plan
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  where to take samples. Here is a yes or no question.
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  Do waves from surface storms reach the bottom of Challenger
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  Deep? No, Surface waves lose their
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  energy within the upper part of the ocean.
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  The bottom of Challenger Deep does not feel those waves,
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  however. There are deep currents and
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  internal waves in the ocean, and slow moving water can still
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  carry fine particles along the trench floor.
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  Exploration at these depths teaches us about materials and
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  engineering too. Pressure housings are often made
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  from titanium or special ceramics.
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  Electronics are placed inside oil filled housings to equalize
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  pressure. Batteries and motors must work
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  in cold temperatures. Even small design details
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  matter, like how cables are routed and how weights are
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  released. Teams test equipment and
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  pressure chambers before an expedition to make sure
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  everything survives the descent. Here is another trivia question.
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  The Triest used a liquid inside its large float to provide
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  buoyancy. What was that liquid?
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  It was gasoline. Gasoline is less dense than
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  water and is relatively hard to compress, so it helped the craft
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  float once the weights were released.
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  Modern Subs often use syntactic foam, a solid material filled
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  with tiny hollow spheres, to provide lift without compressing
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  too much. Scientists also listen to the
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  deep ocean. Sensitive microphones called
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  hydrophones can record sounds from earthquakes, whale calls
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  from far away, and even the noise of rain at the surface.
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  Recording sound helps researchers track natural events
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  and study how noise travels through different layers of
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  water. Here is a yes or no question.
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  Have scientists found tiny bits of plastic inside small
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  crustaceans collected from very deep trenches?
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  Yes. Studies have found microplastic
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  fibers and fragments inside amphipods from some of the
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  deepest trenches on Earth. This tells us that plastic waste
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  can break down into very small pieces and spread widely through
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  the ocean. Scientists use this information
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  to understand how pollution moves and how it might affect
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  animals. What about the sea floor itself?
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  The bottom of Challenger Deep is mostly fine mud made from
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  particles that settle over time. This mud can include bits of
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  minerals, shells from microscopic organisms, and dust
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  that blew over the ocean. The chemistry of the water just
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  above the sea floor shows how oxygen and other dissolved
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  substances change as organisms use and recycle materials.
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  By measuring these changes, scientists learn about the
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  carbon cycle and how the deep ocean stores carbon for long
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  periods. Here is one more question for
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  you. Do you think researchers have
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  detected small natural radioactivity signals in deep
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  sea sediments that help tell how fast particles settle?
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  Yes. Scientists measure isotopes like
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  lead 210 and cesium 137 in sediment cores to estimate how
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  quickly layers build up. These measurements are like a
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  timestamp that helps create a history of the sea floor
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  environment. Did you know that different
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  dives have reached slightly different maximum depths at
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  Challenger Deep? This is because the sea floor is
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  not perfectly flat and also because instruments have margins
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  of error. Pressure sensors, sound, speed
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  and water and exact locations all affect the final number.
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  That is why you may see slightly different depths reported by
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  different teams. Scientists do not go just once.
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  Repeat visits let them check for changes after earthquakes, study
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  seasonal differences in sinking particles, and test new
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  instruments. Some expeditions leave long term
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  devices, called moorings that hold instruments at fixed depths
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  to collect data for months or years.
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  Let's wrap up with a quick review.
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  Challenger Deep is the deepest known point in Earth's oceans,
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  located in the Mariana Trench in the western Pacific.
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  Conditions there include darkness, cold temperatures,
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  near freezing, and pressure over 1000 times what we feel at the
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  surface. A few crude missions starting
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  with the Trieste in 1960 have reached the bottom, and modern
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  submersibles and robotic Landers continue to study it.
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  Life exists there, including amphipods, sea cucumbers and
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  many microbes adapted to high pressure and low food supply.
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  Scientists map the sea floor, record sounds, measure water
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  chemistry and collect sediments to learn how the deep ocean
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  works. Some surprising findings include
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  deep sea microplastics and special markers and sediment
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  that tell time. Every new dive helps us
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  understand Earth's oceans better and reminds us how much there
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  still is to explore. And beyond breakfast, feeling
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  finds adventures waiting. Don't be late.
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  Today's the day we celebrate. Kid Cast Daily starts your day.