Research Vehicle Reaches the Bottom of the Ocean 165
timothy found BBC coverage of the voyage of the Nereus, which on May 31 dove to the bottom of the Challenger Deep in the Marianas Trench. Only two vehicles have accomplished this feat before, the last 11 years ago. "The unmanned vehicle is remotely operated by pilots aboard a surface ship via a lightweight tether. Its thin, fibre-optic tether to the research vessel Kilo Moana allows the submersible to make deep dives and be highly manoeuvrable. Nereus can also be switched into a free-swimming, autonomous vehicle. ... The Challenger Deep... is the deepest abyss on Earth at 11,000m-deep, more than 2km (1.2 miles) deeper than Mount Everest is high. At that depth, pressures reach 1,100 times those at the surface."
Re:I wonder if my great^8 grandkids (Score:5, Interesting)
I'm impressed with the two guys who did it *manned* in the 60s
from tfa :
In January 1960, Jacques Piccard and Don Walsh made the first and only manned voyage in a Swiss-built bathyscaphe known as the Trieste.
The vessel consisted of a 2m-diameter (6ft) steel sphere containing the crew suspended below a huge 15m-long (50ft) tank of petrol, designed to provide buoyancy.
During the nine-hour mission, the two men spent just 20 minutes on the ocean floor; enough time to measure the depth as 10,916m (35,813 ft).
When will (Score:2, Interesting)
Cable? Why? (Score:5, Interesting)
Somebody smarter than myself, please comment on why we need a cable over a distance of 11km? There's a ton of off-the-shelf radio equipment that can easily handle that distance with very high bitrates.
I can imagine two possible problems:
First, the ocean might simply be good at blocking transmissions.
Second, the varying pressures and temperatures might distort a signal to the point where it is unusable. I'm referring to dielectric effects and the fact that the dielectric constant would not be constant in this sort of operation. But would it be "constant-enough"?
Re:I wonder if my great^8 grandkids (Score:3, Interesting)
Re:I wonder if my great^8 grandkids (Score:5, Interesting)
I'm impressed with the two guys who did it *manned* in the 60s
from tfa :
In January 1960, Jacques Piccard and Don Walsh made the first and only manned voyage in a Swiss-built bathyscaphe known as the Trieste.
The vessel consisted of a 2m-diameter (6ft) steel sphere containing the crew suspended below a huge 15m-long (50ft) tank of petrol, designed to provide buoyancy.
During the nine-hour mission, the two men spent just 20 minutes on the ocean floor; enough time to measure the depth as 10,916m (35,813 ft).
Yeah, I remember seeing a special on that when I was younger (like 10 years ago), and I still remember it, because it's such an awesome story. I really suggest that if anyone is bored you look this story up, it's really awesome.
The sad thing is that once they hit the bottom, the sand down there was so fine that it threw up a cloud of it that never cleared during the time that they were there, so they didn't get to see much except for what they saw right before they landed!
-Taylor
Re:how hard can it be? (Score:3, Interesting)
It's pretty certain that the components are not functionning at 1 atmosphere of pressure. Give or take, the rule of thumb when diving is that the pressure goes up by 1 atmosphere for every 10m of depth. With a depth of 11000m, that's 1100 atmospheres of pressure. That's one of the most reliable methods they use to measure depth, actually.
It's not the outside pressure that causes things to crumple. It's the difference between outside and inside pressures. With that in mind, and keeping in mind that electronics don't get decompression illness, I think it'd make more sense to pressurize the sub. Especially considering that it's a lot easier to contain high pressure at the surface than it is to withstand it at the bottom... case in point, I have an aluminum scuba tank sitting in my basement which is pressurized to 3200 PSI. That's over 217 atmospheres of pressure inside the can, a fifth of the way to the pressure at the bottom of the ocean, and it's not even close to the highest pressure scuba tank I've ever seen. (it's about the max pressure you can have with a yoke connector, but a DIN connector can take a significantly higher pressure).
The bottom line, though, is that you can make a sub that can withstand a *much* greater depth by designing/building it to be pressurized on the inside, too.
Re:how hard can it be? (Score:5, Interesting)
Uhh. those solid state components you're thinking of tend to have voids in them, e.g. what's under that lid on the CPU.. a bare die and a bunch o' bond wires. Squish city at 1000 Atm.
What about wires? More than enough pressure to push water through the wire using the insulation as a tube.
It is REALLY, REALLY hard to design stuff to work at 1000Atm. What do you use for bouyancy? (Trieste used gasoline.. a liquid that is about the same compressibility as water) Syntactic foam with silica microspheres is fairly popular, because the tiny hollow spheres are pretty strong.
Interestingly, it's harder to design something that won't crush than something that won't explode. That is, building a compressed gas tank to hold 20,000 psi is easier than building one that won't crush under 20,000 psi.
Re:Cable? Why? (Score:2, Interesting)
Re:Cable? Why? (Score:2, Interesting)
Steve
Re:how hard can it be? (Score:5, Interesting)
You seem to know a bit about submarines so perhaps you could answer a question that has puzzled me. If you build a submarine like an onion with a hull inside a hull and put pressurized water / air between the two hulls to half the outside pressure would each hull then only need to be strong enough to resist half the external pressure?
I can't see the flaw but it feels wrong because it seems to imply that it would be at least theoretically possible to build a submarine out of sheets of tin-foil as long as there were enough layers and the pressure could be maintained accurately enough.
Re:I wonder if my great^8 grandkids (Score:4, Interesting)
Depends - Quote [physorg.com]:"By mimicking a brick-and-mortar molecular structure found in seashells, University of Michigan researchers created a composite plastic that's as strong as steel but lighter and transparent."
CC.
Re:What They Aren't Telling Us... (Score:1, Interesting)
This happens frequently bringing back fish and organisms from as little as 800-1000m. Gas expansion in body cavities or swim bladders cause the animals to explode because they are hauled to the surface much faster than they can adjust to the surrounding pressure differences. It ain't a pretty sight at time, including the eyes popping out of the fishes heads :S
Best approach to avoid is an extremely slow recovery, so give the mermaid enough time to put on her makeup while you're hauling her up, and you might avoid the eye-popping experience.