Lesson 23: Technology II

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. Scuba diving Submersibles Compact submarines that can explore the deep via an onboard computer system or remote operation How do scientists explore underwater? Photo: NOAA Explorers wear suits for diving with light, self-contained units of oxygen

4. 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 ROV: Remotely Operated Vehicle Photo: NOAA The Institute for Exploration’s ROV Hercules, aboard a NOAA ship

5. 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 AUV – Autonomous Underwater Vehicle Photo: NOAA/Navy This AUV runs on solar power

6. HROVHybrid Remotely Operated Vehicles • 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 The HROV Nereus

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

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 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 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!

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