
Unmanned sub touches deepest part of world's ocean - naish
http://www.cbc.ca/technology/story/2009/06/03/nereus-mariana-trench-dive.html?ref=rss
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jmatt
I'm glad to see new efforts in exploring deep oceans. It's amazing to me how
little effort is spent exploring our own planet. We know very little about the
deep parts of the ocean.

The world has had the technology to go there since 1960 when a two man crew in
the _Trieste_ went to the Challenger Deep. I think the reason new subs don't
have a crew is because it's cost prohibitive. Since the median ocean depth is
1/3rd of the depth... most of these subs aren't engineered for extremes. My
guess is the next time a crew goes there it'll be funded by some rich explorer
looking for a challenge (Richard Branson, etc). Hopefully he'll make some real
innovations and share them with the community. In the meanwhile it's good to
see a new robotic sub visiting.

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

<http://en.wikipedia.org/wiki/Challenger_Deep>

EDIT: Added a few sentences.

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jonah
And at $8 million, quite inexpensive compared to space exploration.

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wallflower
"The water pressure at the bottom of the Mariana Trench is like having the
weight of three SUVs on your big toe"

"The fiber optic tether transmits high bandwidth data only, not power...As the
vehicle moves through the water, the tether is laid from the vehicle, avoiding
any dragging of the tether through the water. This decreases the energy load
on the vehicle and the strength requirements for the tether; hence its size
and weight can be minimized"

[http://www.spawar.navy.mil/robots/pubs/HROV%20Tether%20Ocean...](http://www.spawar.navy.mil/robots/pubs/HROV%20Tether%20Oceans08.pdf)

Cached:
[http://74.125.47.132/search?q=cache:jrgXAl_Pvf8J:www.spawar....](http://74.125.47.132/search?q=cache:jrgXAl_Pvf8J:www.spawar.navy.mil/robots/pubs/HROV%2520Tether%2520Oceans08.pdf+spawar+systems+center+%2B+tether&cd=3&hl=en&ct=clnk&gl=us)

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spkthed
This is amazingly awesome. At the end it talks about how this device connects
to the surface using cabling thinner than a human hair. Technology just blows
my mind.

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10ren
_but [steel cable] systems would snap under their own weight in the pressure
conditions of the Mariana Trench._

Does that make sense? I don't see how pressure can make things weigh more...
but I guess 10km of steel cable will have some weight. I'd have thought you'd
make the cable have the same net density as water, so it is effectively
weightless.

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ars
> I'd have thought you'd make the cable have the same net density as water, so
> it is effectively weightless.

It still has momentum. So it could be broken just by trying to pull it - even
without the weight.

And you are right - "pressure conditions" is not correct. It's simply the
weight of the cable.

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radu_floricica
I'd guess even changing its density wouldn't be trivial. Whatever material you
choose it'll have to stand the pressure without compacting.

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siegler
The Sanmina/SCI fiber cable used is only .25mm diameter and 11 km of the stuff
weighs only .173 kg (less than 1/2 pound).

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jws
The Woods Hole page on Nereus is at <http://www.whoi.edu/page.do?pid=10076>

