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Ocean Research Methods and Technology. Science 8: Water Systems
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Ocean Research Methods and Technology Science 8: Water Systems Curriculum Outcomes Addressed• Provide examples of how technologies used to investigate the ocean floor have improved over time (110-8)• Identify some strengths and weaknesses of technologies used to investigate the ocean floor (210-3)• Provide examples of public and private Canadian institutions that support scientific and technological research involving the oceans (112-5)• Describe some positive and negative effects of marine technologies in the ocean (113-2)
Submersibles • A submersible is a small vehicle or craft designed for under water research and exploration. • Submersibles differ from submarines because submarines are fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersibles are usually supported by a surface vessel, platform, or shore team. • There are two categories of submersibles: • Manned craft: HOVs • Unmanned craft: ROVs, AUVs • Submersibles are used for Submersibles have many uses, including oceanography, underwater archaeology, ocean exploration, equipment recovery, and underwater videography and photography.
Submersibles Manned Submersibles (Carry people) Unmanned Submersibles (Do not carry people) HOV (Human Occupied Vehicle) ROV (Remotely-Operated Vehicle) AUV (Autonomous Underwater Vehicle) Alvin Bathyscaphe ROPOS ABE Jialong
Manned Submersibles: HOVs • HOV stands for “Human Occupied Vehicle” • Description: HOVs are submersible crafts that take people under water and to the depths of the ocean • Use: To allow scientists to get a first hand experience of studying the ocean. HOVs are used to • Advantages: Unlike ROVs and AUVs, HOVs can carry people. • Disadvantages: The amount of time spent under water and the depth of travel is limited by having people on board. They are quite costly to build and maintain.
HOV Examples • The Bathyscaphe Trieste was the first manned submersible to reach the deepest part of the ocean (11 km deep) in 1960. • The Jialong submersible can reach depths of up to 7,000 meters below sea level. • Among the most well-known and longest-in-operation submersibles is the DSV Alvin (deep-submergence research vessel), which takes 3 people to depths of up to 4,500 metres deep. Alvin is owned by the United States Navy, and has made over 4,400 dives.
HOV Example #1: ALVIN Alvin is built to withstand the crushing pressure of the deep ocean. The titanium-hulled sub can remain submerged for 10 hours under normal conditions, although its life support system will allow the sub and its occupants to remain underwater for 72 hours. It is capable of maneuvering around rugged bottom areas and can hover in mid-water to perform scientific tasks or take still and video photography.
Bathyscaphe Trieste Manned Submersibles Jialong Submersible ALVIN http://www.whoi.edu/alvin/ http://www.buyexploreryachts.com/images/news/submersible_submarine.jpg
Unmanned Submersibles: ROVs and AUVs • Because the depths of the ocean are very dark and extremely cold (around 1°C), scientists use unmanned robotic craft to explore them. • There are two main types of unmanned submersibles: • ROVs (Remotely-Operated Vehicles) • AUVs (Autonomous Underwater Vehicles) • These have different qualities so they are used for different tasks; the main difference is that while ROVs are physically connected to the ship by a cable, AUVs are not connected to the ship.
Unmanned Submersible: ROV • ROV stands for “Remotely-Operated Vehicle” • Description: Free-floating unmanned submersibles • Use: To complete complex manipulations (i.e., get an oil well ready for drilling at the bottom of the ocean floor) and for sampling the seafloor • Advantages: ROVs are free-floating and not connected to a ship; The vehicle is self-sufficient – it carries its own energy source and is programmed with instructions that allow it to carry out an underwater mission without assistance from an operator on the surface; it can go on missions that • Disadvantages: It cannot carry scientists; they are costly to build and maintain.
ROV Example: ROPOS • An example of an ROV is the ROPOS (Remotely Operated Platform for Ocean Science), which was originally built in Vancouver for ocean research. The ROPOS is connected to a ship by a fibre optic cable and is controlled by a pilot onboard the ship. The cable provides power and communication to ROPOS and allows live video and other data to be sent back to the ship as it is being collected. The ROPOS is able to dive 5000 meters deep (5km).
ROV: The ROPOS • The ROPOS has a variety of sampling equipment attached • Video cameras • Robotic arms for taking samples of rocks or organisms • Bottles for collecting water samples • A “biobox” for collecting biological samples • Asuction sampler that can “vacuum” up sediments/organisms
ROV: The ROPOS Schematic image of ROV deployment and support equipment.
The ROPOS ROV – Instrument Example • Using a custom designed "push-core" sampler, ROPOS uses one of its manipulator arms to collect 12,000+ year old clay for geological analysis. http://oceanexplorer.noaa.gov/technology/subs/ropos/media/core_sediment.html
Unmanned Submersible: AUV • AUV stands for “Autonomous Underwater Vehicle” • Description: Unmanned submersibles that are often attached to a research vessel by a tether/cable • Use: AUVs are best for surveys that can be programmed ahead of time and accomplished without supervision; they are used to measure ocean water characteristics such as temperature and salinity, map the seabed, inspect subsea installations (i.e., pipelines), and to lay underwater cable. • Advantages: It can undertake missions over long ranges at reasonable speeds; Aside from programming the submersible, there is not a lot of time investment because scientists can program the AUV in advance; easy to handle because of small size • Disadvantages: AUVs are connected to a ship by a cable, so their movement is limited by the length of the cable and the location of the ship; limited control once they are deployed; their small size prevents them from storing capabilities
AUV Example: ABE (Autonomous Benthic Explorer) One specific example of an AUV is the ABE (Autonomous Benthic Explorer). The ABE runs on batteries and can stay under water for more than a day. The ABE is unattached from the ship and houses a computer. Among other things, the ABE can create detailed maps of the vent areas, measure water propertiessuch as temperature and salinity, and detect the presence of microscopic life.
Gravity Corer • Gravity corers are used to drill into the ocean floor to collect samples of seafloor sediments (sand, rock, etc.) to find out information about it. • Gravity corers are always connected to the ship. • It is dropped off the side of a ship until it hits the ocean floor. It then drills into the ocean floor, collecting samples of sea floor sediments as it is pulled up again (similarly to a straw). • Advantages: It is simple to use, sturdy (does not break easily), and it does not take a lot of time or money to maintain it. • Disadvantages: It can be heavy and awkward to carry/maneuver.
Gravity Corer Sample collected from the sea bed
Sediment Trap • Description: Sediment traps are containers used to collect particles falling to the ocean floor such as dead sea creatures, tiny shells, dust, and minerals. It is a broad funnel with a collecting jar at the bottom. • Use: The information collected helps scientists understand how fast nutrients and other elements move from the ocean surface to the deep ocean (ocean circulation). • Advantages: Currently, this is the only way to get data about the amounts and kinds of material that surface waters transport to the deep ocean; Easy to used; fairly inexpensive • Disadvantages: It takes a long time to collect enough sediment to study; the traps have to stay vertical (upright) in order to be accurate, so their tilt angle has to be monitored closely.
Spray Glider • Description: Robotic submarines that navigate underwater without a human crew onboard and without cables connecting them to research vessels at the sea surface. They carry a variety of sensors, and are programmed by researchers to go where they are needed to do research. • Use: They record temperature, salinity, and movement of areas of the oceans. These measurements are used to research ocean circulation and its effect on the global climate. • Advantages: They can provide a look at entire sections of ocean basins. Unlike humans, who need to stop for breaks, gliders can stay underwater as long as 6 months and travel at a speed of 20 kilometers per day. • Disadvantages: They are sometimes put off path by ocean currents because they are light weight, and they cannot go deeper than 1,500 meters at this time, so the depth of research is limited.
Acoustic Doppler Current Profiler (ADCP) • Description: Similar to Sonar, the ADCP is a current meter used to measure water current velocities using Doppler Effect sound waves that are scattered back from the particles within the water. • Use: To measure water current speed/velocity and ocean depth • Advantages: ADCPs are much more accurate than long strings of current meters that were used in the past; they can measure up to 1000 meters of depth • Disadvantages: They run out of batteries quickly; If the water is very clear, the pings may not hit enough particles to produce reliable data; bubbles in turbulent water or swimming fish can cause the instrument to miscalculate the current
TowCam Underwater Camera • Description & Use: Specially designed digital camera system that photographs the seafloor as it is towed along the ocean bottom behind a research vessel. It is also equipped to take samples of water and collect rocks from the seafloor; It snaps a new photo every 10-15 seconds. • Advantages: It provides very high quality digital imagery of seafloor terrains to 6,000 meters depth; it can also collect rock/lava samples and water samples; unlike regular underwater cameras, the TowCam can withstand the extreme environment of the ocean bottom – it can take pictures in total blackness, crushing pressure, and freezing temperatures. • Disadvantages: It cannot be "steered" because it is towed behind a ship; The images from the TowCam are not viewable in real-time. They have to be downloaded from the digital camera once the system is back on deck, a process that takes about 40 minutes
Sound Navigation and Ranging (SONAR) • Description & Use: A system for the detection of objects under water, and for measuring the water's depth and map out the seafloor by emitting sound pulses and detecting or measuring their return time. • Advantages: It is very accurate and not too expensive • Disadvantages: SONAR waves can interfere with whale and dolphin echolocation
#3: National Research Council Institute for Ocean Technology (NRC)
