James Cameron in the Mariana Trench

[theprestige]

Yeah, that was my thought too. Now if he had managed to do some actual scientific discovery, I would have been even more impressed.

Get ready to be even more impressed.

 

[lionking]

One thing I wonder is how certain are scientists that Challenger Deep is the deepest point in all oceans?

 

[Checkmite]

Sonar I reckon.

 

[Pulvinar]

Drain plug.

 

[Olowkow]

In the video Cameron talked about voice communications being possible. I have heard of hydrophones being used for 1 km or so, but 7 miles? Does anyone have any idea how this communication is achieved?

 

[Olowkow]

One thing I wonder is how certain are scientists that Challenger Deep is the deepest point in all oceans?

I worked with a guy who spent a lot of time on nuclear subs. I was really surprised to learn that they do not navigate using any kind of sonar, generally. They rely on extensive accurate maps of the ocean floor, and inertial navigation. I found that difficult to believe, but that's the way it is apparently.

 

[Marduk]

In the video Cameron talked about voice communications being possible. I have heard of hydrophones being used for 1 km or so, but 7 miles? Does anyone have any idea how this communication is achieved?

is the answer "shouting"?

 

[steve s]

I worked with a guy who spent a lot of time on nuclear subs. I was really surprised to learn that they do not navigate using any kind of sonar, generally. They rely on extensive accurate maps of the ocean floor, and inertial navigation. I found that difficult to believe, but that's the way it is apparently.

Sonar would give away their position. Those maps, though, were created using sonar.

Steve S

 

[Olowkow]

is the answer "shouting"?

Nope! ESP! Or some serious power on their hydrophones.

 

[lionking]

Sonar I reckon.

I understood that much of the ocean floor hasn't been explored at all, so couldn't there be a deep trench anywhere else?

 

[Checkmite]

I understood that much of the ocean floor hasn't been explored at all, so couldn't there be a deep trench anywhere else?

Well I'm sure that much of the ocean hasn't been directly explored in a scientific sense; but I'm pretty sure it has been fairly well sounded, only because the world's seafaring nations have a stake in maintaining safe navigation charts.

 

[SezMe]

Explored and mapped are two different things. I have no doubt that every Navy that has subs knows the elevation (depth) of every square meter (metre?) of the ocean floor. That does not mean someone has actually viewed, visited or sampled it.

ETA: Kinda duplicate of Checkmite.

 

[Buckaroo]

Get ready to be even more impressed.

My favorite line:

Today, the Nereus and the DEEPSEA CHALLENGER are the only known vehicles capable of reaching these depths.

Bolding mine.

 

[theprestige]

in the video cameron talked about voice communications being possible. I have heard of hydrophones being used for 1 km or so, but 7 miles? Does anyone have any idea how this communication is achieved?

the deepsea challenger‘s pilot will be alone, but he’ll spend a lot of the journey talking: He’ll narrate a “dive log” to two small cameras (two are needed to create 3-d video) inside the sphere. He’ll also talk to the surface through several systems—one with a 19-mile (30-kilometer) range underwater. When necessary, he’ll be able to send text messages, which are more efficient than voice communications. The submersible’s mother ship, the mermaid sapphire, and the 30-foot (9-meter) rigid-hulled inflatable prime rhib are each equipped with two transducers—one on board and another suspended on a cable about 330 feet (100 meters) below the water. The sub also has a backup acoustic modem/transponder powered separately from the sub’s main battery. Once the sub surfaces, it will also use a vhf marine radio to communicate with the crew.

hth. hand!

 

[steve s]

Well I'm sure that much of the ocean hasn't been directly explored in a scientific sense; but I'm pretty sure it has been fairly well sounded, only because the world's seafaring nations have a stake in maintaining safe navigation charts.

Also keep in mind that much of the ocean floor is vast, featureless stretches of abyssal plain. According to Wiki, over 50% of the earth's surface is abyssal plain. There's really no need for subs to know every little bump and gulley. Trenches form at the subduction zones where two tectonic plates meet. Those areas have probably been pretty well mapped.

It's sort of like flying a Cessna over Iowa at night. You don't need to know where every little hill is. But if you're flying over Alaska, you better have a damn accurate map showing every mountain.

Steve S

 

[WildCat]

I don't want to wait that long...

I think he discovered that it's wet down there.

 

[WildCat]

My favorite line:

Bolding mine.

I'm pretty sure if you threw a Chrysler off the ship it would be able to sink to the bottom...

 

[WildCat]

Also keep in mind that much of the ocean floor is vast, featureless stretches of abyssal plain. According to Wiki, over 50% of the earth's surface is abyssal plain. There's really no need for subs to know every little bump and gulley. Trenches form at the subduction zones where two tectonic plates meet. Those areas have probably been pretty well mapped.

It's sort of like flying a Cessna over Iowa at night. You don't need to know where every little hill is. But if you're flying over Alaska, you better have a damn accurate map showing every mountain.

Steve S

Plus subs can only go down a few hundred feet before getting crushed like a tin can. So they really don't need to know about anything deeper than that. It's shallow water they need to worry about.

 

[Olowkow]

Seawolf class submarine, test depth published is 2000 feet. Actual limit is likely quite a lot more.

 

[arthwollipot]

Get ready to be even more impressed.

Okay, cool. I thought he was just down there for filmmaking. But it's still a case of "go down, see what's there", which is exploration and laudable of itself, but it's not exactly science.