Exploring on their own, robotic submarines unlock the secrets
beneath the waves and ice of our oceans.
Theyre anxious because their invention is out there
entirely on its own. "Dorado is making the decisions
it needs to make, because when it is underwater, its
completely out of communication with us," explains
James Bellingham, director of engineering at the Monterey
Bay Aquarium Research Institute, or MBARI, in
Dorado represents a unique new class of free ranging,
untethered robot submarines called Autonomous Underwater
Vehicles, or AUVs. The MBARI invention roams the cracks and
crevices of the bays canyon much like a traffic
helicopter, dipping and diving to take stock of forces
shaping life in the marine sanctuary. Just as a surfer can
feel a cold current passing by her toes, the small ship
senses what flows beneath the ocean surface: glowing
marine microbes, poisonous blooms of algae, and rolling
By gliding through the seas, AUVs are giving scientists an
extraordinary new view of the ocean. The robot submarines
can track oceanic events unfolding over a range of depths.
They can survey a whole square kilometer of the ocean in
just a few hoursa richness of detail impossible to
obtain from traditional surface research vessels or by
towing underwater vehicles behind ships. AUVs easily
explore below polar ice or operate in high seas, opening a
window on truly uncharted territory. Researchers are now
using the unique traveling abilities of these vessels to
answer questions on everything from global climate change
to sea floor tectonics. In the quest to build these
versatile underwater explorers, MBARI and the Woods Hole
Oceanographic Institution, in Massachusetts, are leading
"The ocean is terribly understudied. You can look in
one spot in the ocean and things might be very different if
you just move over one kilometer," says Bellingham.
"In that way, the ocean is so much more difficult to
track than the atmosphere, unless you dip something into
Dorado is MBARIs dipper. It can continuously monitor
and record the temperature, saltiness, pressure, and light
levels of the water it swims through. It also sends out
sonar to identify the ocean floor below, a looming cliff of
rock, or even ice overhead. Researchers reconstruct
thousands of bits of collected data into a
three-dimensional picture of the ocean.
That picture might reveal sediments wafting up from the
bottom, warm and cool waters mixing to melt Arctic ice, or
vast clouds of microscopic marine organisms, called
plankton. No video camera can capture the information in
these pictures, Bellingham says. Video footage might
uncover fantastical unknown deep-sea creatures, but it
doesnt record the temperature of their environs, nor
can it count how many animals live in a given area
of the ocean.
MBARI engineers named their robot submarine after the
Dorado dolphinfish, hoping it would be "free-ranging,
slick, and speedy" like its biological counterparts,
says Drew Gashler, one of the AUV engineers. Suntanned and
pony-tailed, Gashler works in the AUV lab, which was
recently added to MBARIs beachfront complex at the
midpoint of Monterey Bay. The lab is a workshop filled with
scattered wrenches and pliers, plastic vehicle casings,
spools of colored electrical wire, and several laptop
computers. Next to the lab, a saltwater test tank 11 meters
deep waits to try out the oversized bathtub toys. Through
two large bay doors, the lab opens to the dock where
Dorados support ship, the Zephyr, a retired 26-foot
pilot vessel, is moored.
"Dorado comes in chunks, just like Legos," says
Gashler. Modular by design, the sturdy plastic vehicle has
a pointed nose cone and a tapered tail cone that ends with
a blue plastic propeller. These two pieces directly snap
together, or can also take on one or two middle sections in
between that hold multiple scientific tool packages.
"You can operate it on Monday for Billy Biologist and
on Tuesday, you can operate it for Jimmy Geologist,"
Gashler says. With all pieces assembled, the vehicle
stretches 5.5 meters long and half a meter wideabout
the size of two dolphins, end to end.
Gashler opens the tail section to reveal the vehicles
guts: its computer brain, a hard drive for storing data,
motion sensors that detect pitching and rolling, and the
propeller motors. The sensitive electronics are housed
under a glass bell that keeps water out and resists
pressure up to 6,000 meters deep. Once Dorado submerges,
other sensors record the properties of the seawater that
floods its compartments.
Designing Dorado to navigate by itself proved tough.
Navigating by global positioning satellites or dead
reckoning only works at the oceans surface. Dorado
instead calculates its underwater position by listening for
pings from sonar transponders scattered in known locations,
and uses gravity sensors to tell which way is up. Its
propeller acts as a three-in-one tool: It propels by
spinning, acts a rudder by moving left and right, and
controls depth by moving up and down. Dorado might follow a
programmed path at a certain depth or skim along at a
certain height above the bottom, tracing the terrain with
As the robot submarine sails along, its brain receives
feedback from navigation and motion sensors so that the
vehicle can dodge hazards or stay on course. If something
goes wrong, computer programming gives Dorado enough smarts
to finish its mission, or at least reach the surface
safely. Coastal environments are full of hazards such as
steeply rising shelf bottoms, piers, and ship traffic.
Ensuring that an AUV comes back with its data is critical.
Otherwise, says Bellingham, "your entire career is
sitting on the bottom of the ocean and all you have left is
an embarrassing story to tell your buddies around beer
It takes only two people on a small boat to launch Dorado
on its way to record a slew of data. On a typical route, it
travels along in one direction, but oscillates up and down
from the surface to 60 meters below. When finished, it pops
to the surface and signals, "Im done," via
a radio modem. Once its back on board, scientists
simply plug into the AUV and download enough data to keep
them busy for the next several months.
JOHN RYAN, A PHYSICAL OCEANOGRAPHER at MBARI, has chomped
through AUV data for the last year and a half. He studies
how physical structures and properties of the ocean change
where marine lifeforms appear. "We get a 3-D view as
the AUV zigzags back and forth and yo-yos up and down to
sample the whole region," says Ryan, pointing to a
series of rainbow-colored cross-sections of the ocean on
his computer screen.
Each slice is a snapshot of the sea that he created using
data collected by Dorado. The colors represent gradients of
the waters properties, just like colors on a weather
map show the gradient of temperatures across the country.
By overlaying the slices in a composite, Ryan can see all
of the dynamics in that segment of the ocean.
Using this technique, Ryan is studying how blooms, or
growth spurts, of tiny single-celled algae are born. The
blooms are important because they can dictate the feeding
patterns of fish, which in turn become food for larger fish
and sea creatures. Thus, the algae can influence the
oceans whole food chain. Sometimes, for instance,
growths of toxic algae introduce a poison that works it way
up to the top of the food chain, potentially harming marine
mammals, birds, and even humans.
In August 2000, Ryan used Dorado to map an algal bloom in
Monterey Bay. To monitor the growth, he attached a special
light-reflecting sensor to Dorado. The sensor detects a
specific shade of green light reflected by chlorophyll
pigments found in the marine organisms. From these
measurements, he mapped the bloom to a subsurface layer 5
to10 meters thick. Another sensor, meanwhile, sends out red
light and then records how much is reflected back by
particles suspended in the water.
When Ryan overlaid the cross-sections recorded by the two
sensors, he clearly saw the cause of the bloom. The slice
from the red-light detector revealed the same subsurface
layer of algae, but also showed sediments coming up from
the ocean bottom. Ryan speculates that these sediments
contain nutrients that feed the algaea process
scientists had assumed was happening, but had never
witnessed before now. The sediments might also trigger
blooms by bringing dormant algae spores to the warm, sunlit
surface, he says.
Whats more, says Ryan, the water carrying the
sediments is very cold. That means it came from deep within
Monterey canyon in a coastal process called upwelling, in
which water from the bottom of the ocean rises up to
replace water blown out to sea by winds. This year, Ryan
hopes to use Dorado to determine whether upwelling is a
constant influence on algae growth in the bay.
"We caught a glimpse of a process that may be there
all the time and have a persistent effect on the ecology of
the bay. Now we can go back out there and look at it again
with the same technology," he says. "Ultimately,
we want to be able to predict what conditions are likely to
result in a bloom."
While Ryan used the AUV during summer days, another MBARI
oceanographer, Steve Haddock, took it "night
swimming." Haddock studies the distribution of
glowing, bioluminescent plankton in the ocean. Besides the
wondrous phosphorescent beauty that these organisms bring
to the sea, they also give scientists a way of measuring
the living particles at the base of the marine food chain.
Just as photosynthesizing plants support the terrestrial
food chain, one kind of photosynthesizing algae, called
phytoplankton, keep the ocean ecosystem healthy. Haddock
hopes to predict the abundance of the plankton from the
blue-green light that many of them give off.
To measure bioluminescence, Dorado uses a device called a
bathyphotometer, a cylinder the size of a paper towel roll
that sucks up a water sample and stirs it around to
stimulate any plankton inside to shine. The device
amplifies and records the tiny sparkles of light.
"Inside the bay, we are trying to predict from
circulation patterns where these lumps of ocean that have
high bioluminescence came from," Haddock says. His
slice of ocean from Dorados data showed glowing
plankton in the upper 30 meters of water. The organisms
drop off sharply and disappear at about 12 kilometers
offshore. This tells Haddock that the plankton feeding all
life in the bay stays relatively close to shore, sometimes
concentrated in pockets that move very little.
We didnt have to do anything to get this, just
drop the AUV in and pick it up," Haddock says with a
smile. Most oceanographers work with a view of the sea
thats like putting on a scuba mask and looking
straight down below a ship, he says. If they want a
different view, they have to move the ship. "But the
AUV gives us a way to get an entire swath," he
SCIENTISTS NEED A BETTER perspective of the ocean under the
polar ice as well. Last October, MBARI researchers and
engineers put on their parkas and climbed aboard a U.S.
Coast Guard icebreaker to take their brainchild under the
Arctic ice north of Norway. Their experiment was a test run
for the Atlantic Layer Tracking Experiment (ALTEX), an
international project to determine the fate of warm
Atlantic water that enters the Arctic Ocean. Many climate
researchers believe that the first effects of global
warming will appear in the polar regions, as warmer waters
melt away the thick ice covering the polar oceans.
Before the invention of AUVs, scientists measured
temperature and ice thickness of polar waters once a year
from a Navy nuclear submarine traveling under the ice. But
the Navy is gradually retiring its polar class of
submarines. And, researchers would like to track ice
thickness throughout the year. So, in collaboration with
others, MBARI designed a full-length, modified version of
Dorado that can swim just beneath the ice for more than
1,000 kilometers. The plastic vehicle cruises along at a
much closer distance to the ice layer than a nuclear
submarine can safely navigate, and returns more precise
One particular challenge was crafting the AUV so that it
could surface periodically through the ice to check in with
researchers via satellite. To pull the trick off, engineers
dreamed up an ingenious solution: an "ice buoy"
that ejects from the ALTEX vehicle through a swinging door
and rises to the underside of the ice. The device releases
a lithium pellet that reacts with seawater and creates
enough intense heat to burn through the ice layer. Once it
pops to the surface, the buoy deploys a satellite antenna
to send its data by e-mail to the scientist, reporting on
ocean conditions and ice thickness.
The crew of engineers began testing the AUV in the open
water created by the icebreaker, keeping an eye out for
polar bears. After a few short trips out and back went
according to plan, they took a deep breath, gave the AUV a
helping push to dive down, and sent it under the ice. After
what one crew member called "the longest 15
minutes" aboard the monthlong cruise, cheers and high
fives went around when they spotted the yellow vehicle in
the rendezvous area.
Gashler designed the test programs, which he calls the
"baby steps" of ALTEX. He stresses the importance
of working out bugs while still in open water. "If it
doesnt work, hold the phone, were going to test
it again until it does," he says. Once the $500,000
vehicle goes under the ice, theres no way to retrieve
it if it breaks down. "The ocean is big and we
dont have a string attached," Gashler says.
"So its a nerve-wracking thing because the AUV
is expensive and one of a kind."
For most oceanographers, however, half a million dollars
looks like a steal. "From the perspective of buying a
car, that looks expensive, but you have to look at the fact
that an average research ship costs $20,000 to operate for
one day," says Chris von Alt, an engineer at the Woods
Hole Oceanographic Institution in Massachusetts. Alt and
his colleagues have built robot submarines similar to
Dorado, but with different talents. Their vehicles launch
easily from rubber Zodiak boats, work over whole seasons
for many years, and only cost a month worth of ship
research days. One model is available commercially for
scientists to purchase and adapt to their own research
Alt wryly points out another advantage to robot subs.
Recently, he and his colleagues took one of his AUVs on
test runs off the New Jersey coast, with graduate students
following the course of the vehicle from a ship. "The
students were getting seasick, feeling miserable and cold,
while we were in a warm room onshore having a good
time," he says.
To delve deeper into areas left unmonitored by
oceanographers, WHOI engineers developed the Autonomous
Benthic Explorer, or ABE. Shaped like the Star Trek
Enterprise, this vehicle can glide down to 6,000 meters to
levitate above the ocean bottom. Al Bradley, an ABE
engineer and caretaker, explains how the 1,600-pound
vehicle differs from the lightweight Dorado.
"If you are flying in a light plane, you dont
dare fly into low valleys because the mountains may climb
faster than you can, so you stay well above the mountains.
MBARIs vehicles are optimized for mid-water or flat
areas," he says. Conversely, ABE is designed to take
on the rugged terrain of geologically active seafloors,
including vertical cliffs, valleys, and mountains. Instead
of one main steering propeller, ABE has seven thrusters
oriented to allow for movement in any direction, including
reversing to travel up overhanging cliffs.
WHOI oceanographers have sent the benthic explorer out to
explore cooling underwater lava flows, investigate how new
seafloor forms, and study how mineral deposits form in
cracks near super-hot water surrounding volcanic vents.
Many scientists dont believe the data from ABE at
first because theyve never seen such a detailed view
of the bottom of the sea, Bradley says. "The greatest
reward to us as engineers is seeing the scientists tearing
their hair out trying to figure out what to do with this
data that is both exasperating and exhilarating," he
AUVs are revolutionizing the way oceanographers observe the
ocean, Bradley says. "Trying to study the bottom of
the ocean from a ship is like aliens trying to discover
what a football field looks like from orbit. All they see
is a tiny green blob. If they use deep-sea submersibles
with a video camera, it would be like seeing the species of
grass and insects on the field through a galactic
microscope. What you need is the helicopter that hovers and
scans back and forth and gives you a survey that tells you
it is a rectangle of grass with white lines on
In other words, robot submarines give scientists a powerful
way to spy on the ocean. Eventually, scientists hope to
dock AUVs out at sea, where they could alert computers on
shore when events such as toxic algal blooms occur. Then,
with the push of a button, scientists could deploy the AUV
to monitor the event, without ever getting their own feet
wet. The knowledge gleaned from these free-roving ocean
sentinels will reshape our understanding of marine
chemistry, geology, and biologyforces that give the
planet weather, continents, and life.
"The ocean is fundamentally opaque," says
MBARIs Bellingham. "The only way to visualize it
is to introduce sensors on a platform like an AUV."
The AUV takes researchers to places they otherwise
couldnt explore, such as the Arctic basin. "The
Arctic is the canary in the coal mine for global climate
change. The ice there is in fact warming and melting. But
is it global warming or the Arctic oscillation, a normal
climate cycle?" asks Bellingham. "You really need
an AUV to get at these problems."