> He is to cram his 6-foot-2 frame into a personnel sphere just 43 inches wide, forcing him to keep his knees bent and his body largely immobile. The dive plan calls for him to remain in that position for up to nine hours.
My heartfelt sympathies go out to Cameron--it sounds like riding coach on a transcontinental flight.
Wikipedia seems to indicate that the Kola superdeep borehole has since been surpassed in 2008 and 2011 by oil drilling operations. The current record holder is Sakhalin-I at 12,345 meters: http://en.wikipedia.org/wiki/Sakhalin-I
In fact, if you read that article more carefully, you'll find you're not reading the relevant part of that article.
The Kola Superdeep Borehole set two records: deepest point reached, and longest borehole. The latter record was, as you say, surpassed twice by oil operations. But if you look at the context of the comment I was replying to, it's clear that Dr Stalker was talking about deepest point reached (surely no one thinks Cameron could dig a multiple-kilometer hole from his submarine). And so it is the deepest-point-reached record that is relevant, which was not surpassed by oil operations. This is because those oil boreholes are diagonal, with a large horizontal component.
Also, based on the information I could find, I don't actually know how deep the KSB is, relative to sea level, because I don't know what altitude its "ground level" is, and all the depth measurements I could find are relative to ground level.
By the way, the extra amazing thing about the Kola well is that core was collected over the entire well depth. This means that the drill string had to be pulled out hundreds of times during drilling to recover the core, and explains why the project took 20-odd years to complete.
Decompression sickness only occurs when a person is under elevated pressure for a period of time, and then the pressure is released. Pressurizing the sub could in fact cause the decompression sickness, not prevent it.
For this sub, during descent the pilot's chamber compresses and air is drawn out of that chamber to keep the pressure constant (this from JC's site). Rather unlike the airplane, into which the air is pumped from the outside, usually from the engine compressor's bleed, to keep the pressure from falling too low as it ascends.
> Decompression sickness only occurs when a person is under elevated pressure for a period of time, and then the pressure is released. Pressurizing the sub could in fact cause the decompression sickness, not prevent it.
Only a too rapid depressurization will cause decompression sickness. Unless the sub is pressurized to a much higher pressure than normal atmospheric pressure, decompression sickness won't be an issue.
According to National geographic (http://news.nationalgeographic.com/news/2012/03/120308-james...) the entire sub is only going to shrink by about 2.5 inches. If we assume that the shrinkage only occurs on the 43 inch pilot sphere, then the lost volume is only about 16% of the total original volume, which means pressure at the bottom is about 120% atmospheric pressure. Since most airplanes are pressurized to 10.9 psi, which is about 75% of atmospheric pressure at sea level (14.9 psi) I don't think decompression sickness will even be an issue.
> For this sub, during descent the pilot's chamber compresses and air is drawn out of that chamber to keep the pressure constant (this from JC's site). Rather unlike the airplane, into which the air is pumped from the outside, usually from the engine compressor's bleed, to keep the pressure from falling too low as it ascends.
I googled for James Cameron's website and couldn't find anything. Could you please provide a link?
Yes, obviously an airplane is going to pump air in from somewhere to keep the chamber at a higher pressure than the ambient environment and a submarine with a shrinking chamber is going to remove air to keep the chamber at a lower pressure than the ambient environment. However, both an airplane and a sub are designed to keep a chamber at a specific pressure that is relatively close to normal atmospheric pressure, which prevents humans in the chamber from being at risk for decompression sickness, short of some sort of catastrophic failure.
So it starts out at as high a pressure as it will end up at the bottom? Because of course the problems of pressure are reversed in deep sea submersion as compared to high altitude flight. You have to pressurize a plane, the submarine will pressurize itself.
> So it starts out at as high a pressure as it will end up at the bottom?
Ignoring shrinkage of the chamber (not insignificant), yes the human chamber will be at the same pressure at the surface and at the bottom. Counting in shrinkage due to pressure, the absolute pressure change will be less than the absolute pressure change you experience when you get on an airplane.
> Because of course the problems of pressure are reversed in deep sea submersion as compared to high altitude flight.
Of course the pressure problems are reversed. But both the airplane and the submarine prevent humans from experiencing decompression sickness by keeping the absolute change in pressure small enough that decompression sickness isn't an issue.
No. Airplanes are not air tight therefore they require pressurization. Submarines are air tight therefore no pressurization is required.
If the air in a submarine starts to 'pressurize' the last thing you're worried about is the bends. In a pressurization event on board a submarine you're going to be far more worried about how to get the ocean out.
The other issue is that when the air pressurizes it heats up almost instantly, it's generally believed that a large leak in a sub would create a wall of flame.
"it's generally believed that a large leak in a sub would create a wall of flame."
What complete and utter rubbish. Please provide a single reference for this "general belief". Or better still, apologise for posting crap.
Air, and gases generally, do heat up when compressed adiabatically (without exchange of heat with surroundings). But filling half the sub with water - that's a large leak, right? - and hence doubling the pressure would only produce about a 60 degree increase in temperature - not quite enough for a wall of flame eh? - if no heat was lost from the air to such things as jets of cold water entering the sub in this scenario.
"When the hull of a sub fails, it normally fails ni one location, and water shoots in through that spot, relieving the stress on the rest of the structure. That's why all the wrecks you see in video from actual crash sites look so intact.
Of course, the inrush of water also has the effect of rapidly pressurizing the inside of the sub 'till it matches external pressure. This rapid compression of the air inside has the effect of drastically raising the temperature, so what the victems inside probably see is an explosion (big wall of flame rushing through the inside)."
"Interesting point. Since compression is quick, it is adiabatic, PV^\gamma = K applies. So if the pressure doubles, the volume of air reduces to .6 of its original volume the temperature will increase by a factor of 1.2 (eg from 300K to 360 K) which is pretty warm but not enough to ignite anything. When the wall of water has consumed 80% of the volume, the temperature is up to 570 K (300 C). So the sailors at the end of the sub watching the oncoming wall of water get fried before they drown."
"In a modern submarine, where crush depth is likely to be deeper than 1,000/2,000 feet, the hull is likely to implode, collapsing completely. In the process, the air inside the hull is compressed very rapidly, raising the internal temperature by several hundred degrees. Everything flammable inside, including the crew, is incinerated in the fraction of a second before the water rushes in to crush what's left. It is, indeed, believed to be very fast, probably faster than anyone aboard would be able to comprehend. You would simply and instantly go from being alive and wondering when it was going to happen to being dead and not knowing it had."
"With the rapid compression of the air, there would be a simultaneous step rise in both pressure and temperature. The air pressure would rapidly approach, but not exceed, the water pressure. The temperature would, of course, be proportional to the air pressure, but what the actual numbers are I am not certain. I am not sure one way or the other whether they would raise to the point of combustion, but I agree that it’s possible. In any case, they would be high enough to cause severe burning of the exposed body surfaces. Of course, the body would also experience the effects of the sudden high pressurization, resulting in burst eardrums, a ruptured body, perhaps cracking of the skull (which under a pressure increase of the rapidity would be like it’s own pressure-tight space, just as would the main body), the eyes would probably burst (implode), and there would probably be bursting of many blood vessels. Of course, both any burning effect, already mentioned, and the result of a rapid pressure impulse on the body would both be in a fractional second. Loss of consciousness and death would be near instantaneous, as you state. I can see perhaps enough of a window for the body and conscious to experience perhaps a very brief moment of thought and sensation, but if there is any at all, it would be exceedingly brief.
Given what we know from actual hull crushes (and I’m sure that someone knows waaaaay more than I do since I’m just going by what we learned as part of being nuclear submariners), the entire submarine would not necessarily crush all at once. One example is the Golf-class submarine that we recovered from the Pacific floor as part of our espionage operations (Howard Hughes’ Glomar Explorer, etc.) Though we only recovered about the front third of that submariner, we obtained about two thirds of the interior works, since the submarine breached at some point in the rear and the pressure surge slammed the interior forward. A second example is the U.S.S. Scorpion, our nuclear SSN which was lost in the Atlantic in 1967. We believe that we captured on sound detection devices the sequential collapse of pressure-tight bulkheads as it crushed, indicating that the hull breached to sea pressure at some point (certainly the bow compartment based on the cause for sinking) and then as the boat sank and the rising sea pressure exceeded the strength of the bulkheads they collapsed in turn from forward to aft. Of course, in this case, each compartment is acting as its own pressure-tight space. In both submarine cases, of course, the indication is that the whole sub did not crush all at once, but experience hull failure at one point, and then had a pressure wave travel inside the boat. (While it’s horrifying to consider, there is a good likelihood that the men in the rear-most compartment of the Scorpion heard the collapsing of the forward bulkheads before the engine room bulkhead failed.) Given the experience of the Soviet sub, we also know that the forces are strong enough to rip machinery from it’s mounts and move it, so this adds the final event on the bodies inside the sub, as they are mutilated in varying ways as they are caught in both the movement and crunch of machinery and/or collapsing bulkheads or the hull."
Theoretically, temperature rise during compression is given by:
T2/T1=(P2/P1)^((n-1)/n)) where n is about 1.3 for air.
If we start at 70F, T1= 530 R (degrees Rankine).
P1 = 1 atmosphere
P2 = 2000 ft water = 867 psi = 59.4 atm
T2/530 = (59.4)^(1.3-1)/1.3)
T2 = 530(59.4)^(0.231)
T2 = 5302.57 = 1362 deg R = 901 deg F
"I've heard speculation that the implosion would be similar to what happens when you set off a bomb calorimeter, in which the extreme pressure rise would heat up the internal atmosphere to the point that combustible materials would be incinerated as the water rushed in.
For illustration purposes, it can be calculated that a hole in the submarine's hull of just 1-foot diameter (at a depth of 800 feet) would fill the associated compartment in just a few seconds. Larger hull ruptures would flood the submarine essentially instantaneously."
"The myth that I heard a number of times when I was in the Navy was that the air in the sub will actually detonate due to the sudden increase in pressure which causes it to heat rapidly, and the crew will die from the ensuing firestorm long before they get a chance to die from drowning or the pressure."
"The "long before" comment was considering that all the things that are going to happen to you in this scenario are going to happen pretty quick. But the implosion will be ship-wide since the hull is likely to give way in more than one location and, LA class subs at least, effectively have only one compartment with people inside (there are actually 2 but the door is usually open). The pressure will be felt throughout the ship at the same time and therefore the fire will happen ship-wide as well."
I agree with commentators here. This, and other deep sea stuff, is awesome. I'm fascinated that it's being done by private companies, and the competition between Cameron and Branson just adds to the awesomeness. (Branson appears to be losing badly.)
I don't believe there is any specific limit, as long as you give enough time to change the pressure gradually. However at higher pressures you need to reduce the oxygen and co2 concentrations (since at higher pressures they dissolve too easily). (You want to keep the partial pressure constant, even though the absolute pressure goes up.)
Water is roughly incompressible and ~10 meters (33 feet) of it will generate 1 atmosphere of pressure, so at 6 miles deep, I would guess even a very small safety factor would dominate any gains from pressurizing the capsule (I don't know anything about diving, but Wikipedia says that saturation diving is good down to about 150 meters, and the most extreme experiments went down to about 700 meters).
What's great is how much of this tech is going to the open market. The foam that's being used for this is already on the open market. It's really an ideal model of how private research can help our society as a whole.
> Regardless of what one may think of his movies; this is bad ass.
Hmmmmm.... Aliens, Titanic, Avatar... not to mention Terminator, T2, The Abyss. Many people consider his movies to be bad ass and innovative as well. He's one of the very few directors where I can count on him setting his own bar so high that I'm going to love whatever he makes. Along with Ridley Scott and Spielberg, and more recently Nolan and Fincher joining their ranks, in my eyes.
The pilot does sit in a sphere. It's just like the Trieste; it's not possible to make a sphere that is strong enough to withstand the pressure and light enough to remain buoyant. To solve this they attach the sphere to a larger buoyant vessel.
The non-spherical part of the Trieste was filled with gasoline for buoyancy, this submersible uses some kind of high density foam.
Since I was curious about the relative densities, I looked it up and asked Google to convert to your archaic units. Water, at -30C, is around 60 lbs/ft³, so indeed the foam is denser.
I was _going_ to claim that water is denser still, way down deep in the ocean. But I thought I'd check it out first, and although I'm not well-educated enough to understand the important parts of phrases like "At 0 °C, at the limit of zero pressure, the compressibility is 5.1×10−10 Pa−1", I can understand this phrase: "The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume."
Oh, my bad. I misrecalled a detail from the featured article, thinking it had claimed that temperatures were very very low, so I picked the lowest temperature in that sidebar as a rough approximation. Actually, TFA says "near freezing", which certainly much closer to 4C than to -30C.
"He is to cram his 6-foot-2 frame into a personnel sphere just 43 inches wide, forcing him to keep his knees bent and his body largely immobile. The dive plan calls for him to remain in that position for up to nine hours."