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Meet ROPOS
by Peter Tyson
ROPOS may look like an upended refrigerator, but what it lacks
in form it more than makes up for in function. The Remotely
Operated Platform for Ocean Science has more gadgets than you
can shake a five-function arm at (which is one of those
gadgets, by the way). Take a closer look at this deep-sea
robot, one of only four in the world that can dive to depths
of more than
10,000 feet. (Just don't
get too close to that five-function arm. According to a ROPOS
technician, "its jaw could take your arm off.")

Thrusters
ROPOS is powered by pressurized hydraulic fluid. Two vertical
hydraulic thrusters lie in here. There are also two lateral
and two fore-aft thrusters. All told, ROPOS has 30 horses
under the hood when in deep mode, which currently allows dives
to about 10,000 feet but that will soon increase to almost
17,000 feet. (In shallow-water, "liveboat" mode—that is,
in less than 1,200 feet of water and tethered directly to the
ship—ROPOS is a 40-horsepower machine.)
Foam pack
The foam filling this pack aids buoyancy and is so dense that
it cannot be made any denser by the enormous pressure at
10,000 feet. It might be foam, but it ain't light: when in
"liveboat" mode, ROPOS tips the scales at 3,600 pounds, while
in deep mode (shown here), which features nothing more than a
fatter foam pack, it weighs in at a full 6,000 pounds.
(back to diagram)
Vehicle telemetry
Unlike most equipment on ROPOS, which adjusts to the pressure
at depth, this titanium cylinder maintains one atmosphere of
pressure—the same as at the surface. It houses the
delicate telemetry system, which guides the robot based on
instructions coming down through the tether from the
joystick-wielding pilot high above. On the other side of ROPOS
is a separate science telemetry system.
Tether
The 1,000-foot-long tether connects ROPOS to the cage, which
has its own 11,800-foot electrical-optical cable to the
surface. All data, from directional commands sent down from
the pilot sitting in the mother ship to live imagery beamed up
from ROPOS, travel through this thin umbilical.
SUAVE sampler
This flow-injection device samples hydrothermal vent water and
analyzes it for dissolved minerals such as sulfur, lead, gold,
and silver.
(back to diagram)
Lead ballast
Whenever a piece of equipment is added to or removed from
ROPOS, these lead weights are removed or added to compensate.
Fine-tuning the vehicle's trim, which is kept slightly
positive, is vital to ensuring the highest maneuverability.
Five-function arm
The five functions are shoulder up/down, elbow, yaw, wrist
rotate, and jaw open/close. There is also a seven-function arm
(not visible in this picture), with, in addition to those
above, wrist up/down and wrist yaw. Both arms can lift 600
pounds at full extension.
Biobox
Beneath the five-function arm is a hydraulically activated
"biobox." Measuring roughly 30 inches long by a foot wide and
high, it can be thrust out, its lid open and shut, and then
pulled back in.
(back to diagram)
"Pac-Man" sampler
Resembling the video-game snapper, this is the jaw that could
bite your arm off (see above). It's used to collect samples of
known volume from the seabed. Not visible in this photo, ROPOS
also has a rotating sample tray with four sub-dividable
compartments, and a variable-speed, reversible suction sampler
that can pump a respectable
78 gallons a minute.
Fish trap
This cylindrical trap, known to many a fisherman, is simply
set down on the bottom and picked up later. ("We've caught
octopus, crab, seems like everything but fish," a ROPOS
technician admitted.)
Camera
This is ROPOS' main camera. It's a Sony DXC-950
broadcast-quality color NTSC camera with 16x zoom. Out of
sight in this photograph is the SIT, a very-wide-angle,
very-low-light camera. ROPOS' cage also has its own camera.
(back to diagram)
Arc lights
These are 250-watt arc lights, which are brighter and closer
to daylight than the 250-watt incandescent light (seen just in
front of the arc light that is to the right in the picture).
Together, the lights illuminate the ocean floor out to between
50 and 75 feet ahead.
Strobe
This is the strobe light for the main camera.
Still camera
This was a still camera temporarily installed by the
University of Victoria for a specific mission.
(back to diagram)
Sonar
This scanning, color-imaging sonar, modified with a lower
frequency and narrow-beam head for enhanced long-range
response, allows ROPOS to "see" perhaps 350 feet ahead. Such
long-range vision is invaluable in navigating through the
highly variable terrain of a spreading center, where the black
smoker chimneys may be found.
Relay transponder
This relay transponder "pings" continuously. Its signals are
bounced off an acoustic net of transponders placed nearby on
the seafloor. The time lag of each return determines where on
the bottom ROPOS is at any given time. The tracking is
integrated with differential GPS, the ship's heading, and wind
speed and direction. All told, this navigation system enables
ROPOS pilots to know where their charge is to within 20
feet.
(back to diagram)
Peter Tyson is Online Producer of NOVA.
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