00:00Why is it harder to take a submarine to the bottom of the sea than a spacecraft into space?
00:11Hello, Detailed Engineering.
00:12Have you ever wondered why fewer people have visited the bottom of the Mariana Trench,
00:17which is the deepest point in the ocean, than have been to space?
00:21While more than 600 humans have orbited the Earth,
00:25only three have descended to the 11,000-meter depth of the ocean.
00:31It seems contradictory since space is seen as the final frontier,
00:35while the ocean is right here on our own planet.
00:38But the truth is, the seafloor hides a disaster, a harsh, often underestimated challenge.
00:43The pressure.
00:45While spacecraft deal with the vacuum,
00:47submarines face forces capable of crushing steel as if it were paper.
00:51Let's dive into this issue and find out why mastering the ocean depths
00:56can be more complex than reaching Earth's orbit.
01:00First, what makes underwater pressure so frightening?
01:04To understand the difference, we need to compare the environments.
01:07In space, the internal pressure of a spacecraft is about one atmosphere,
01:12like on the surface of the Earth, while the external vacuum exerts zero pressure.
01:17That is, the structure needs to contain the internal pressure, like an inflated balloon.
01:21The pressure that the structure needs to withstand is the pressure
01:24from inside the spacecraft to the outside, which is just one atmosphere.
01:28At the sea bottom, external pressure is immense.
01:32For every 10 meters of depth, the water adds one atmosphere of pressure.
01:37In the Mariana Trench, with its 11 kilometers of depth,
01:40the pressure reaches 1,100 atmospheres.
01:44To withstand this, a submarine needs to be built like an armored tank,
01:49while a spaceship works more like a sealed plastic bottle.
01:53But if the pressure is so high, how come submarines aren't crushed?
01:57To withstand extreme compression, submarines use two secrets.
02:01The spherical shape and the use of exceptional materials.
02:05The spherical shape is the geometry that best distributes forces evenly.
02:10In addition to using titanium, or high-alloy steel, heat-treated,
02:15the submersible limiting factor, which reached the Mariana Trench in 2020,
02:20has a spherical titanium hull that is 90 millimeters or 9 centimeters thick,
02:26to protect only two people.
02:28Even so, a single poorly installed bolt or an imperfect weld would result in instant implosion.
02:35A spacecraft, like the Crew Dragon capsule from SpaceX, uses aluminum,
02:40which is lightweight and ductile, with only 2 millimeters of thickness,
02:44reinforced with carbon composites.
02:46Its function is to contain an internal atmosphere, not to withstand external forces.
02:51But before we continue, let's include a bit of calculation and understand the mass involved.
02:57The hydrostatic pressure P in a liquid is calculated by the formula on the screen,
03:01where Rho is the density of water, which is 1,000 kilograms per cubic meter.
03:06G is gravity, which is equal to 9.8 meters per second squared, and H is the depth.
03:13And considering the Mariana Trench, we have 11,000 meters.
03:18Calculating this results in 107,800,000 Pa, or 107.8 MPa.
03:26At the bottom of the sea, that's enough pressure to crush a block of concrete into powder.
03:31In space, however, the pressure difference is only...
03:365 MPa.
03:37This means that, in terms of magnitude,
03:40underwater pressure is 1,000 times greater than what a spacecraft faces.
03:44To be more precise, it's 1,078 times greater.
03:48If a spacecraft has a leak, the internal air escapes into the vacuum in a relatively slow process.
03:54On the other hand, a submarine at the bottom of the sea suffers an implosion,
03:59where water, which is incompressible, invades any crack at absurd speeds.
04:04In 1963, the nuclear-powered submarine United States ship thrasher imploded at a depth of 2,400 meters.
04:12That pressure crushed the submarine's hull in a mere 0.1 seconds,
04:18reducing it to a pile of metal the size of a refrigerator.
04:21Another example was the submersible Titan in 2023,
04:25which was visiting the wreck of the Titanic,
04:28and imploded at an approximate depth of 3,350 meters.
04:33According to analyses, that means a pressure of 32.8 MPa.
04:39And what about the materials?
04:41Why don't we use titanium in spacecraft?
04:43The thing is, in space, every gram counts.
04:46Using titanium, which is stronger but a bit heavier, would make the launch unfeasible.
04:52That's why spacecraft prioritized lightweight materials like aluminum, carbon composites, and thermal ceramics.
05:00Deep-sea submarines, on the other hand, sacrifice weight for strength.
05:04If you've made it this far and enjoyed the video, make sure to subscribe if you haven't already,
05:09leave a like, and turn on the notification bell.
05:11And if you find our content interesting, consider becoming a member to help us keep producing content here on the
05:18platform,
05:19and to be mentioned in our videos.
05:21And if you're interested in knowing the courses we recommend,
05:23scan the QR code here on the side, or check the link in the video description.
05:27To have access to various opportunities to develop several skills that will make you stand out in your career.
05:34Did you know the water pressure at the sea bottom?
05:37Would you like to go down there in a submarine?
05:39Leave it here in the comments, because I want to know.
05:42On the side, there are two videos you should watch to expand your knowledge and curiosity.
05:47To support us, please like, subscribe, enable notifications, and consider becoming a member.
05:53That's it, engineering fans.
05:55Big hug.
05:56See you next video.
05:56See you next video.
Comments