What Physics Principles Enable Manned Submersibles to Explore the Ocean Depths?

[lsim16]

Help!

what are all the physics priciples behind making and using a manned submersible?
what are all the factors that needed to be considered and how does the submersible deal with these issues (i have found some articles about submarines but submersibles are different)
how does it go up and down
how does it support life while it is underwater
how long can they last?
how deeep can they go?

anyone help would be greatly appreciated

 

[Astronuc]

Well, one can google on "Alvin" and "Trieste", or try Wikipedia for starters.

http://en.wikipedia.org/wiki/DSV_Alvin

http://en.wikipedia.org/wiki/Bathyscaphe_Trieste

On January 23, 1960, she reached the ocean floor in the Challenger Deep, carrying Jacques Piccard (son of Auguste) and Lieutenant Don Walsh, USN. This was the first time a ship, manned or unmanned, had reached the deepest point in the sea. The onboard systems indicated a depth of 37,800 ft (11,521 m), but this was later revised to 35,813 ft (10,916 m). (However later and more accurate measurements made in 1995 have found the Challenger Deep to be shallower, at 35,798 ft (10,911 m)). The descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the 3 hour 15 minute ascent. They observed small soles and flounders and noted the floor consisted of diatomaceous ooze while on the bottom.

Deep Sea Submersible's have gone to the deepest part of the ocean, the Marianas Trench ( http://en.wikipedia.org/wiki/Mariana_Trench ), Challenger Deep - http://en.wikipedia.org/wiki/Challenger_Deep.

See also http://en.wikipedia.org/wiki/Bathyscaphe_Trieste_II

For more on Alvin - see Woods Hole's Alvin site - http://www.whoi.edu/marops/vehicles/alvin/index.html

Obviously, the DSV need to be heavier (less bouyant) than the surrounding ocean water. Then to rise, they dump mass (weight) to become more bouyant. To support life, they must withstand high pressure on the outside, while maintaining near atmospheric pressure inside. In addition, they must have sufficient oxygen and heating.

The sites provide more information.