Remembering Sealab 138
An anonymous reader writes "'Some people remember Sealab as being a classified program, but it was trying not to be,' says Ben Hellwarth, author of the new book Sealab: America's Forgotten Quest to Live and Work on the Ocean Floor, which aims to 'bring some long overdue attention to the marine version of the space program.' In the 1960s, the media largely ignored the efforts of America's aquanauts, who revolutionized deep-sea diving and paved the way for the underwater construction work being done today on offshore oil platforms. It didn't help that the public didn't understand the challenges of saturation diving; in a comical exchange a telephone operator initially refuses to connect a call between President Johnson and Aquanaut Scott Carpenter, (who sounded like a cartoon character, thanks to the helium atmosphere in his pressurized living quarters). But in spite of being remembered as a failure, the final incarnation of Sealab did provide cover for a very successful Cold War spy program."
Sekrit Canadian Locations (Score:5, Informative)
Re:The ocean frontier - not (Score:4, Informative)
"...but none of them actually got built. The one "underwater hotel" in the world is a recycled two room research habitat. "
Phew, glad that the guys in the link below don't know that. (Top 5 underwater hotels)
http://blog.hotelclub.com/top-five-underwater-hotels/ [hotelclub.com]
Helium (Score:5, Informative)
He sounds like Yakky Doodle:
http://www.youtube.com/watch?v=Uaa9ZJ2KSoQ [youtube.com]
Divers sometimes use helium to replace some of the nitrogen. If you're at pressure, then the amount of nitrogen that goes into your blood stream can cause nitrogen narcosis. If you lower the partial pressure of N2 (by using He) then this is less likely.
Helium also diffuses quicker than nitrogen. But this can mean that decompression is a bit more difficult.
It talks about it a bit here:
http://en.wikipedia.org/wiki/Trimix_(breathing_gas) [wikipedia.org]
Re:The ocean frontier - not (Score:5, Informative)
Going through the list there
Jules Undersea Lodge: a converted two bedroom research facility. Located in a lake 21 feet down. Dive entry.
Utter Inn: a box just below the surface with surface entry not much different from the lower sections of a boat except there is water between the upper and lower sections. Only one room.
Hydropolis: looks like it was intended to be a proper hotel though only barely underwater and surface entry but the article you linked claims it as "under construction" but wikipedia links to another article that claims it is "nothing more than a pile of blueprints". Looks like it got nixed in the wake of the credit crunch.
Poseidon Undersea Resorts: this does actually sound like an undersea hotel but from their website it is not at all clear whether it was ever finished or not. Trying to get a "booking request form" out of their website gives the message "Thank you for your interest in Poseidon Resorts. We welcome you to contact us after September 15, 2009.". This suggests the website hasn't been updated in years.
Istanbul: I can't find any evidence of this underwater hotel actually exiting either.
Re:The ocean frontier - not (Score:5, Informative)
One REALLY big difference between undersea and space is air pressure. If you want people to be living near 1atm of pressure then in space you have to deal with at most 1atm of pressure on your hull. Underwater you're dealing with more than 1atm of pressure before you reach depths on par with a big swimming pool. That means you need a lot less structural strength in your spacecraft.
All the messing around with gas mixtures undersea is about trying to work at higher pressures to cut down on that disadvantage, but it gets really messy - people are designed to live at 1atm on 20% O2. In space that is fairly easy to provide, and deep underwater it is almost impossible.
Now, in space you have lots of other issues to deal with I'll grant you, and the cost of moving around is pretty high too (well, maneuver in space is cheaper per mile than underwater, except that stuff is thousands of miles apart so you do a LOT more of it and once you're close to a gravity well you build up kinetic/potential energy and changing your energy state is much harder). Underwater you can just use buoyancy to do half the work.
Re:The ocean frontier - not (Score:5, Informative)
I think that undersea conditions are actually more challenging than Space, at least LEO Space. You've got a terrible corrosion problem underwater, typically saturation level humidity, and the pressure differential to a "shirtsleeve" environment is higher as soon as you get below 60' (at 30' depth, you can saturation dive indefinitely with no special gasses and no decompression needed...), and then there's the mixed gas / decompression thing if you want to run your environment at a higher pressure to make a larger hull practical.
A blowout in the space-station can be plugged with duct tape (from the inside)... a blowout in an undersea habitat at 100' depth is considerably harder to deal with.
It is a shorter trip to "the undersea world," but the challenges pile up very quickly as you go down.
Re:The ocean frontier - not (Score:4, Informative)
BTW, you have that exactly backwards.
hmmm I'm not sure he does? Consider:
At 30 feet depth, you need to handle a 14psi differential
This is your own statement, and (without checking your actual #) it's true, because water is so heavy (massive). But change your depth 30 ft in the atmosphere and there is relatively little pressure difference. You can go up and down in an elevator all day and you won't explode. This is because air is so light (lacking mass).
The GP's point - I think - is that if you have a 30 foot tall underwater structure filled with pressurized gas, the pressure created by the water will be (by your number) 14psi greater at the bottom part than at the top part. But because the gas pressure differential is much less variant by depth the gas pressure at the top is the same as at the bottom. So you actually have to worry about blowing out the top of your open-on-the-bottom underwater highrise. There goes the whole 0 psi differential idea, but in the opposite direction one might expect. Maybe an easier problem to deal with (if you keep your structure squat), but still something to make sure the engineers account for.
Unless I've got it all wrong?