December 9, 2003
the first time since 1960, US scientists will be able to explore the
deepest parts of the world’s oceans, up to seven miles below the
surface, with a novel underwater vehicle capable of performing multiple
tasks in extreme conditions. Researchers at the Woods Hole
Oceanographic Institution (WHOI) are developing a battery-powered
underwater robot to enable scientists to explore the ocean’s most
remote regions up to 11,000 meters (36,000-feet) deep.
The hybrid remotely operated vehicle, or HROV, will be able to operate
in two modes: as an autonomous, or free-swimming, vehicle for wide area
surveys, and as a tethered, or cabled, vehicle for close-up sampling
and other tasks. In the latter mode, it will use a novel fiber
optic micro cable only one thirty-second of an inch thick, a major
departure from the large heavy cables typically used with tethered
vehicles. The deep-sea vehicle will require new technologies such as
ceramic housings for cameras and other electronic equipment to
withstand the pressures at the vehicle’s extreme operating depths.
for the four-year, $5-million HROV project is provided by the National
Science Foundation, with additional support from the US Navy and the
National Oceanic and Atmospheric Administration. Principal
investigators are Andrew Bowen and Dana Yoerger of WHOI’s Deep
Submergence Laboratory (DSL) in the Applied Ocean Physics and
Engineering Department and Louis Whitcomb, an Associate Professor in
the Department of Mechanical Engineering at Johns Hopkins University.
Whitcomb is also a visiting investigator in DSL. The new vehicle
will undergo initial trails in three years.
The HROV will provide routine access for scientific research in areas
of the ocean that are virtually unexplored – the deep trenches, which
are some of the most active earthquake zones on earth, deep transform
faults and under the polar ice caps. It will be compact enough for
quick deployment from virtually any ship in the world for rapid
response to changing environmental conditions, such as volcanic
eruptions or earthquakes.
Trieste descended with Don Walsh and Jacques
Piccard. The Japanese remotely operated vehicle (ROV) KAIKO dove to the
bottom of the trench in 1995. KAIKO was lost earlier this year, and no
operational vehicles currently exist that are capable of reaching this
Unlike other vehicles, the
HROV will be designed to be reconfigured aboard ship to operate in two
different modes, depending on the scientific need. As an autonomous or
free-swimming vehicle, the HROV will be launched from a surface vessel
and descend through the ocean. During its journey to the bottom
it will collect information and images, mapping and surveying the
seafloor for up to 36 hours on battery power. This capability will
permit scientists to examine broad areas of the seafloor efficiently
and to find areas worthy of more detailed study. When its
mission is complete, the vehicle will return to the surface where the
stored data can be recovered and analyzed. When areas of further
research interest are identified, the vehicle can be reconfigured in
its remotely operated or tethered mode. This can be done on the
same research cruise, thereby optimizing scientific return and avoiding
lengthy delays in making important scientific discoveries.
After transformation on deck to a remotely operated vehicle (ROV), the
HROV is launched using an armored fiber optic cable and depressor. Once
clear of the vessel and surface currents, the vehicle is released from
the depressor at about 1,000 meters depth (about 3,300 feet) and free
falls to the seafloor using a descent anchor assembly. During
the free fall it pays out the fiber optic micro cable from two small
canisters, one mounted on the depressor and the other on the descent
anchor assembly attached to the vehicle.
The HROV uses the fiber optic cable to communicate with the support
ship but not to supply power. The small, lightweight cable, only
one-thirty second of an inch in diameter and adapted from US Navy
applications, allows the HROV to operate and maneuver at unprecedented
depths without the high-drag and expensive cables and winches typically
used with deep sea ROV systems. Once the HROV reaches the
bottom, the descent anchor assembly is jettisoned and the vehicle
continues its mission while paying out up to 20 kilometers (about 11
miles), of micro cable from a third canister mounted on the vehicle.
Using two-way, real time communications via the micro fiber, the HROV
is remotely controlled by an operator on the surface vessel.
Mission durations are planned to be as long as 36 hours and include
collecting samples, taking photographs and video, and conducting
detailed mapping and seafloor characterization. When the mission is
complete, the HROV jettisons the micro fiber and drops its ascent
weights for the trip to the surface. Untethered, it guides itself to
the armored cable depressor near the surface, latches onto the cable to
the surface ship above and is recovered aboard ship. The micro-fiber is
then recovered for re-use.
“The HROV will enable, for the first time, routine scientific research
in the deepest parts of the ocean, from 6,500 meters to 11,000 meters,
a depth we currently cannot reach,” says Richard Pittenger, WHOI Vice
President for Marine Operations. “It will also afford access to
other very hard to reach regions such as under the Arctic ice cap.
The HROV’s real-time, wide-band link to the surface will put the
researcher in the loop to view, assess and command the vehicle
throughout the duration of dive missions. It is the first
capable and cost-effective technology that will enable scientists to
pursue research projects on a routine basis in areas they have long
wanted to study but have been unable to reach. HROV technology
will help answer many questions about the deep sea.”
Hole Oceanographic Institution (WHOI) is a private, independent marine
research and engineering and higher education organization located in
Falmouth, MA. Its primary mission is to understand the oceans and their
interaction with the Earth as a whole, and to communicate a basic
understanding of the ocean’s role in the changing global environment.
Established in 1930 on a recommendation from the National Academy of
Sciences, the Institution operates the US National Deep Submergence
Facility that includes the deep-diving submersible ALVIN, a fleet of
global ranging ships and smaller coastal vessels, and a variety of
other tethered and autonomous underwater vehicles. WHOI is organized
into five departments, interdisciplinary institutes and a marine policy
center, and conducts a joint graduate education program with the
Massachusetts Institute of Technology.