1. Lesson 23:
Technology II

2. 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

3. How do scientists explore underwater?
Scuba diving
Submersibles
Compact submarines that can explore the deep via an onboard computer system or remote operation
Teacher’s note:
SCUBA stands for “Self-containted underwater breathing apparatus”– this always comes up at the Bowl!
The scuba pictures show oxygen tanks attached to a buoyancy system (large picture), a pressure gauge that informs divers of the amount of air that is left in the cylinder (top small picture), and a demand regulator that lowers air pressure from the breathing cylinder, dispensing air as the diver needs it (bottom small picture).
Photos:
Scuba equipment: Accessed: November 2010
Submersible: Accessed: November 2010
Photo: NOAA
Explorers wear suits for diving with light, self-contained units of oxygen

4. ROV: Remotely Operated Vehicle
Photo: NOAA
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
Teacher’s Note: ROVs were used to explore and study the Titanic.
Photo: Accessed: November 2010
The Institute for Exploration’s ROV
Hercules, aboard a NOAA ship

5. AUV – Autonomous Underwater Vehicle
Photo: NOAA/Navy
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
Photo:
Image courtesy of AUVfest 2008: Partnership Runs Deep, Navy/NOAA, OceanExplorer.noaa.gov
Accessed: November 2010
This AUV runs on solar power

6. HROV Hybrid Remotely Operated Vehicles
The HROV Nereus
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
Photo: WHOI: Accessed: November 2010

7. 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
Teacher’s note: This slide contains a short video showing how AUVs use sonar to map underwater objects. The text on the slide in the beginning is difficult to read, and it indicates that the video is from the AUVfest2008, from May , While in the slide show, simply click the black box to play the video. As long as your computer has Windows Media Player, the video should run smoothly.
Video:
Video courtesy of AUVfest 2008: Partnership Runs Deep, Navy/NOAA, OceanExplorer.noaa.gov
Accessed: November 2010

8. 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
Video: (Accessed March 2011). Movie Credit: U.S. Naval Oceanographic Office.
Teacher’s Note: The links below provide good background information on sonar and the different uses of side-scan and multibeam sonar.
Accessed: November 2010
Accessed: November 2010
(Accessed March 2011) - Overall tutorial on seafloor mapping provides overview of sonar in general, the various types, and its uses.
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.

9. 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

10. 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 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!

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