Lesson 23:

Technology II

Strides in underwater research

• Did you know that most of the ocean (>95%) still hasn’t been explored?

• Technologies developed in recent years have made ocean navigation, research, mapping, and exploration much easier

• Today we’ll learn the basics about:• Remotely Operated Vehicles (ROV)• Autonomous Underwater Vehicles (AUV)• Hybrid Remotely Operated Vehicles (HROV)• Sonar• Electronic navigation

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How do scientists explore underwater?

Scuba diving Submersibles

Compact submarines that can explore the deep via an onboard computer system or remote operation

Explorers wear suits for diving with light, self-contained units of oxygen

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ROV: Remotely Operated Vehicle

Unoccupied underwater robots typically equipped with lights, cameras and sampling devices

Linked to a ship by cables and operated by someone on deck (tethered)

Uses:– To support science,

exploration and navigation– To investigate problems on

larger submersibles– To explore potential scuba

diving sites for safety The Institute for Exploration’s ROV Hercules, aboard a NOAA ship

Photo: NOAA

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AUV – Autonomous Underwater Vehicle

Computer-controlled, unmanned submersibles equipped with sampling technology

Self-guiding and not tethered (attached) to a ship

Technologically advanced: Highly maneuverable; Some can reach depths of 6,000 m or below.

Sample uses: – Take physical measurements

(temperature, dissolved oxygen)– Map the seafloor– Observe, take images of marine

life– Search for underwater mines

This AUV runs on solar power

Photo: NOAA/Navy

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Can operate as a tethered ROV or a programmed AUV depending on what works best for a particular mission

The Nereus is the first HROV, developed at the Woods Hole Oceanographic Institution (WHOI) Deep Submergence Lab

– It employs the most advanced sensing technology available for submersibles

– Its tether for ROV mode is much smaller and lighter than most other ROVs, allowing for better ease of movement

– In 2009, it was the first vehicle to explore the Mariana Trench since 1998

HROVHybrid Remotely Operated Vehicles

The HROV Nereus6

Sonar – SOund Navigating And Ranging

Sonar allows scientists to “see” underwater by transmitting a sound and measuring how long it takes to receive its echo

This technology allows scientists to map the sea floor, identify geological features like the Mid-Atlantic Ridge and discover underwater objects like shipwrecks

AUVs and ROVS are often equipped with sonar so they can provide images of underwater objects and habitats

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Two types of sonar

Side-scan sonar– Primary tool for obtaining details of seafloor

surface– Often used to find shipwrecks and detect

objects on seafloor– Provides high resolution data but over

smaller area

Multibeam sonar– Primary tool for seafloor mapping– Used to generate bathymetric maps (show

depths, features of seafloor)– Provides coverage over larger area but less

resolution than side-scan

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Video shows multibeam and side-scan sonar. Multibeam measures the seafloor depth (multi-colored region under boat) and side-scan identifies objects on seafloor (in back of boat). Movie Credit: U.S. Naval Oceanographic Office.

Electronic navigation

Electronic navigation allows ships to determine their exact location

In the 1960s, Loran-C (LOng RAnge Navigation) was invented to make shipping safer– Uses radio signals from two or more transmitters

to provide latitude and longitude information to within half a mile accuracy

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Electronic navigation

Global Positioning System (GPS) largely replaced Loran-C since the 1990s because it is far more accurate

GPS uses satellites to determine position within 1-100 meters depending on the sophistication of the unit

NOAA uses an advanced system of GPS receivers known as CORS (Continually Operating GPS Research Stations) to obtain positioning information accurate within less than a centimeter!

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Student activity

In today’s activity, you will undertake an activity that simulates using sonar to map the ocean floor.

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