Topics: Fiber Optics
I'd like you to meet ABE.
ABE is a robot. Youll notice that its name is spelled
with capital letters. The "E" stands for Explorer. The B stands
for Benthic, which means the bottom of the oceanthats
where ABE explores. The A is for Autonomous, which
means by itself or without any help.
The last part is what makes ABE different from other seafloor-exploring
vehicles designed and built at Woods Hole Oceanographic Institution. People dive
in the submersible Alvin. Jason is a deep-diving robot, but is
attached by a long tetherlike a long leashto the surface ship. The
tether supplies power to Jason and allows a pilot on the ship to see through Jasons cameras
and to control it using a joystick.
ABE was designed to fly free, without a tether,
near the seafloor. Placed overboard, it spirals downward over several
hours to the seafloor. Once there, it is programmed to navigate a
pre-selected pathmapping the seafloor with sonar, using a CTD
to collect information on the characteristics of seawater, or measuring
the magnetism of seafloor rocks. When ABE has completed its
mission, it rises back to the surface, where it is retrieved.
ABEs most remarkable feature is its ability to travel
at roughly the same altitude above the seafloor, even when the seafloor
rises and falls. If ABEs sonar detects a volcano ahead
of it, it will stop, rise, and fly over the volcano, and then lower
itself back to the same altitude on the other side. Imagine trying
to photograph a mountainous landscape from an airplane flying at
a level altitude. Youd see the peaks well, but miss interesting
details in deep canyons or valleys. ABE can follow the contours
of the seafloor.
ABE can be programmed, for example, to maintain a constant
altitude of 10 meters above the seafloor during a typical 6- to 12-hour
mission that covers 20 to 25 kilometers. ABE has five thrusters
that automatically adjust its position over changing seafloor topography.
Its design also prevents it from rolling from side to side or pitching
forward or back, giving it a very stable ride. Humans cannot control
vehicles underwater so precisely.
ABE does indeed resemble the Starship Enterprise in the original
Star Trek serieswith three torpedo-shaped compartments connected
by struts in the shape of a triangle. (ABE's inventors, Al
Bradley, Dana Yoerger and Barrie Walden, clearly have a sense of
humor: They stenciled the same numbers on ABE that adorned
the side of the Starship Enterprise, NCC-1701.) ABEs two
upper red pontoons contain glass balls to provide buoyancy. This
keeps ABE floating upright. Its third compartment (the lower
pod) contains its computer brains and the batteries that power ABE and
its instruments for 6 to 30 hours, depending on how much power the
Because ABE is autonomous, it can stay at the bottom much longer than
a human-occupied vehicle like Alvin. Traveling at slightly more than 1
mile per hour, ABE can create a finely textured map of seafloor that covers
about 1 by 2 kilometers during one dive.
ABE gives scientists the capability to use more vehicles at
the same timeto collect more information. Last year, ABE was
deployed and left undersea for 20 hours, while the ship moved to
a site 30 kilometers away, where Alvin dove and camera tows
or CTD casts were taken.
Then the ship returned to pick up ABE.
In the future, ABE and other Autonomous Underwater Vehicles (AUVs) will
be designed to dive, collect data, dock at underwater stations, and go to sleep, until
scientistsperhaps directly from their office deskssignal them to wake
up and do other research missions. AUVs will also play a major role at
seafloor observatories, where they may be triggered to wake up to
investigate a sudden, short event on the seafloor that ends longs before a ship
could ever reach the sitesuch as an earthquake or volcanic eruption.
For oceanographers, AUVs offer wonderful new tools that greatly expand
their abilities to boldly go exploring in Earths final frontier.
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