Keith Shepherd is General Manager of the Canadian Scientific Submersible
Facility and pilots both manned submersibles and remotely operated vehicles
(ROVs). On this cruise, he will pilot the ROV known as ROPOS. (ROPOS is an
acronym for Remotely Operated Platform for Ocean Science.) Shepherd gave us his
thoughts on the challenges he faces in using ROPOS to carve a black smoker
chimney off the seabed using a diamond-studded chain saw.
NOVA: How extreme are the conditions working in a hydrothermal vent field?
Shepherd: There are many of thousands of pounds per square inch. For example,
when we were working at full depth in the submersible Pisces IV, the pressure
on the hatch alone was about 100,000 pounds. It's like having 20 pick-up trucks
sitting on top of a hatch that's 14 inches in diameter. So you're really
relying on good engineering to keep things together. And once we get into the
hydrothermal areas, the chemicals coming out of the vents are very corrosive.
Even stainless steel will disappear quite quickly once it's immersed in these
plumes. All the equipment must be carefully maintained to resist these
NOVA: What is the terrain like down there?
Shepherd: Some places where the lava has squirted out, it makes these big
pillow shapes. Other places there's a lava lake where the lava has filled up
and then solidified, and then the hot lava underneath has drained away and
leaves this perfectly flat surface with some spires underneath. In some of
these places, it collapses. So as you fly over these areas, you see these
fields of chimneys and so on, sometimes still connected by a top crust and
sometimes not. Then, in other places, there are large fissures where the Earth
is split open. Some are very, very small and some are big enough to drive your
submersible through and explore.
NOVA: Is it tough driving a sub through a field of black smokers?
Shepherd: There are several things to watch out for. There's hot water that is
300 to 400 degrees Celsius, and if you put something in there you can burn or
even melt it. And as you move up and around the structure, there are different
types of animals growing in different places, and scientists often like to
sample these. It's quite challenging to hold the submersible in a position and
reach out with different equipment and collect the animals, or take chemical or
You're very dependent on the ship holding the position. If the ship starts to
wander off, then it can drag the whole works into cliff faces or other hazards.
Finally, you always have to be aware of how you approached an object and where
your tether is. You don't want to drive up to an object, then spin around the
other side, then continue back around, because you can lasso it with your
NOVA: Is there always a risk that, once you put something overboard, you might
not see it again?
Shepherd: Every time you launch something at sea, there's always a risk that
something can happen: a mechanical or electrical failure, or a weather problem.
It's often said, if you don't want to lose it, don't put it over the side.
NOVA: You lost an ROV once. What was that like?
Shepherd: It was pretty devastating when we got caught in a storm and lost our
ROV. The weather came up suddenly and unexpectedly, and before we could get the
system back on deck, although everybody tried very hard to recover the
submersible, the serious events, mostly due to the weather, caused some
failures in the ship and difficulties getting lines on the sub, and so on.
Eventually the tether parted, and it sailed away. The ship was damaged, so we
couldn't chase after it. That was the last we saw of it.
NOVA: How do you launch and operate the ROV?
Shepherd: ROPOS works out of a cage, or a garage-type assembly, which
simplifies launch and recovery. The A-frame of the ship picks up the cage and
swings it out. As the cage hangs over the water, you pay out the winch, and the
cage goes down towards the bottom. Just above the bottom the cage stops and the
ROPOS swims out, with its tether connecting it to the cage. Then, if the ship
is maneuvering and heaving up and down on the surface waves, then ROPOS, with
its separate cable, is unaffected by the ship motion, which is important if
you're doing delicate work and maneuvers on the bottom.
NOVA: How does piloting an ROV differ from piloting a manned submersible?
Shepherd: They're quite different. With an ROV you're in a room with dim lights
and video monitors showing what's going on at the bottom. But you're surrounded
by many people all doing a multitude of different tasks. That's one of the
advantages of an ROV: you can have many people participating in it. And you can
get up and have a cup of coffee and stretch your legs and shift off being a
NOVA: Is using a chain saw for the first time on a black smoker risky?
Shepherd: It has an element of risk. We're using a Stanley underwater chain
saw. It's basically an off-the-shelf tool that divers often use for doing work
on piers and concrete docks. It has carbide and diamond-embedded blocks in the
chain, and it has been adapted to go deep. We've tried to reduce the risk by
conducting sea trials. We've already had the saw mounted on an ROV and deployed
from a ship, and we've successfully tested the saw on concrete structures—it
was incredible to see the saw cut through the concrete just like a knife
through butter—and even on a granite cliff-face. We're pretty confident that
if we cut into granite, we should be able to cut these structures off.
NOVA: Will cutting a black smoker chimney be as simple as cutting those blocks
Shepherd: The chimneys will introduce several different technical risks, as
opposed to cutting a concrete box alongside a dock. The submersible has to be
positioned properly, and the ship has to hold station. These structures have
always had hot water pouring through them and, once we start to cut, we're not
sure what's going to happen. We can get the saw blade in there and open up a
new passage for the water to come out. Hot water can start squirting out around
the saw blade and back towards the vehicle. I think we'll be far enough away
that it won't be a problem, but it's something we'll be watching very
NOVA: Could the chimneys have changed since you surveyed them last fall?
Shepherd: There could be more growth. Some of the chimneys we're hoping to
recover are inactive and if they could start up again, or if some of the active
ones that we surveyed last year have continued to evolve, it could be much
larger or a much different shape than what we mapped. That could pose problems.
We might have to go down and resurvey some of the chimneys to get the new idea
of shape and size, and then we'll take yet another trip to the bottom to
NOVA: How will you cut the chimney?
Shepherd: Our goal is to approach it with the ROPOS, start up the chain saw and
insert it into the chimney, cut as much material away as we can, come around to
another side, cut some more material way, and then come in at a third side and
cut even more material way. We want to leave some of the structure intact so it
doesn't topple over while we're cutting it.
There are different problems that can come up with plunging the saw into the
chimney. One is, if the sub moves, the blade can bind. We should be able to
just pull it back out and start again. The other one is, if hot fluids start
coming out, you have to decide how much farther you want to push the saw in as
fluid's coming out around it. And once we get around and do one of the last
cuts, then you'll be wondering how stable the chimney is, and that's a fairly
big concern. We want to have the vehicle positioned in such a way that if the
chimney does fall over, it's going to fall clear of us and our tether.
NOVA: Is ROPOS ideally suited for this undertaking?
Shepherd: ROPOS is one of the few vehicles that can do this job, because it can
operate so deep. The second advantage is that it's the only scientific research
vehicle that has the hydraulic power to operate a chain saw, and it also has
two manipulators that are very powerful. So it's more an industrial work
vehicle, and it's well-suited to maneuvering large objects on the ocean floor,
and pulling and cutting things, and so on. It's not as well-suited to doing
survey work that requires very precise control.
NOVA: How ambitious is this project?
Shepherd: It's a challenging project, but we're not trying to do the
impossible; we're not trying to boldly go where no one has gone before. We're
basically applying tools that we've developed and tested, and adapting the
techniques that have been used in the past to go and get the work done. I'm
fairly confident that we've prepared as much as we can.
NOVA: How would your rate your job as far as jobs go?
Shepherd: It's one of the greatest jobs in the world. It's exciting, and you're
always doing different tasks: one day you're engineering in a fiber optics
system, the next day you're troubleshooting some electronics stuff, the next
day you're designing computer systems, the next day you're at sea, operating a
vehicle at depths no one ever goes to. There are very few people that get to do
what I do. I'm very lucky.