AUV – NOAA Teacher at Sea Blog

September 13, 2024November 9, 2024

Lisa Werner: How Does Communication with Popoki Work? September 11, 2024

NOAA Teacher at Sea

Lisa Werner

Aboard NOAA Ship Bell M. Shimada

August 29-September 13, 2024

Mission: EXPRESS Project

Geographic Area of Cruise: Pacific Coast, near Northern California

Date: September 11, 2024

Weather Data from the Bridge (Coquille Bank):

Latitude: 42º58.378’ N

Longitude: 124º50.146’W

Wind Speed: 23.78 knots

Air Temperature: 14.3ºC/57.74ºF

Conditions: Rain

Science Log

Let’s talk about how Popoki, the autonomous underwater vehicle (or AUV), ‘converses’ with the AUV pilot aboard the ship. The map and directions for the route Popoki will be mapping is programmed into her computers ahead of each dive. On this mission, Popoki has been deployed daily, so every evening, the scientists carefully plan out where she will go on each deployment. They also plan the path Popoki will go when on location – this cruise she has made a lot of sawtooth-shaped patterns to give the scientists the greatest survey of what is in the areas they want to study.

photo of a computer screen showing, at center, an image from a computer-generated model of the underwater bathymetry of an area. Overlaid on the image are topographic lines and depth numbers. overlaid on that is a zig-zagging white line showing Popoki's route. — *Of course, tomorrow’s dive pattern is not a sawtooth pattern. The pattern is drawn out in the white lines over the diagram of the ocean floor contour.*

Though this seems like it would be easy to set up Popoki and let her run her course, that is not quite the end of the story. During a dive, the ocean current is sometimes unknown in any given area, so the AUV pilot needs to be able to help Popoki adjust her positioning. It would not be a very big help to get pictures of an entirely different area than the scientists were aiming for because the ocean currents took Popoki to a different area of the sea floor. The scientists also need to be able to help Popoki if she gets stuck on fishing line, or if the conditions above the water change – such as weather changes or vessel traffic – that would require Popoki to surface ahead of her scheduled time.

To communicate with Popoki, an acoustic modem system is used. There is a modem aboard the ship that can send messages to Popoki through a series of chirping sounds. The pitches and lengths of the chirps are all part of the code that Popoki can understand. She has a device that ‘listens’ for these sounds and can then follow the coded instructions to alter her pre-programmed course. She also communicates regularly with the AUV pilot – sending the coordinates she believes she’s at, her depth, battery life, and how many pictures she has taken so far in the dive.

close-up view of a piece of electronic equipment inside a water-proof housing (with the lid removed to show the contents). There are knobs, dials, CAT-5 cables. — *The modem that communicates with Popoki*

Popoki’s communication device points upward, so when deployment is taking place, the scientists place a transducer into the water to use to communicate. Once Popoki is on her way to her programmed starting point, and farther away from the ship, the transducer is removed from the water.

crewmembers, wearing hard hats and life vests, lean over the rail of the ship and use hooked poles to guide a small yellow object suspended from what looks like a fishing pole safely down toward the water's surface. — *This is the transducer that is placed in the water for deployment*

Sometimes there are difficulties with this communication, and this is where the ship’ crew plays a very important role. The officers on the bridge work to position the ship in areas that allow for Popoki and the acoustic modem to speak to each other easily. The angle of the ship will change as Popoki goes through her programmed patterns, adjusting so that the chirps of the modem have a direct line to Popoki. Distance also plays an important part of the communication process – if the ship and Popoki are too far away from each other, there can be interference with the communication. Ocean current, wave heights and lengths, and other sounds coming from the ship can interfere with the communication, as well. The AUV pilot and the ship’s crew work very closely together throughout the entirety of the dive to help the Popoki and the pilot have clear communication.

photo over someone's shoulder of a computer screen displaying a gridded graph. on the graph is a simplified outline of the ship (like a rectangle with a triangle attached to one end) and some dots to the ship's port side — *AUV pilot Jeff Anderson’s screen showing the ship’s position and Popoki’s position (Denoted as dots)*

At this point, you may be wondering WHY do we use Popoki. I’m sure that you can see her benefits in exploring areas we have not yet seen, but the why actually goes much deeper than that (no pun intended). One of the first things Popoki is doing is looking at areas that are being considered for future offshore wind farm sites. There is a great interest in putting wind turbines over the ocean to create renewable energy for our country. Having been on the Pacific Ocean for 2 weeks now, I can definitely attest to the fact that the wind is very strong in these areas, so there is plenty of energy to harvest. Popoki is identifying the deep sea habitats and geological features on the seafloor that would need to be considered when anchoring any wind turbines.

Popoki is also looking at the changes to the habitats as a result of different regulations that have taken place in fishing areas in this region. Some of the locations we have visited were mapped out by Popoki in the past, and scientists are looking to see whether fishing regulations have helped the populations of ocean life return. Finally, Popoki has been looking for evidence of seeps in the ocean floor. These geological areas are spots where cracks in the ocean floor have occurred due to plate tectonics.

underwater image of the seafloor. it's mostly muddy, with only a little relief, but through the center is a dark crack in the floor, with what appears to be steam (maybe hotter water) rising out of it. we can also make out what might be corals, and a fish. — *Picture of an ocean seep (Photo credit: Popoki)*

Personal Log

The ship’s crew spends a lot of time preparing for safety. Just like we have fire, tornado, and lockdown drills in our school, the ship has drills to practice for emergencies as well. They need to be ready for any emergency, and everyone has a role to play. We have practiced the drills each week.

Throughout my time on NOAA Ship Bell M. Shimada, I have gotten to experience some pretty amazing things. However, my absolute favorite moment was getting “Helm time.” That’s right – I got to drive the ship! With Ops Officer Lieutenant Jaime Hendrix and Ensign Megan Sixt guiding me, I got to turn the ship to hard rudder, causing her to drive in a circle. I also got to get her back to her appropriate heading for the transit we were making, and then practice keeping her on course. It was really interesting to see how the ship reacts to the controls and to see what she does! I am so grateful to CO Laura Gibson for this opportunity, and really appreciate the help LT Hendrix and ENS Sixt gave me!

photo of Lisa wearing a bright red survival suit - all we can see of her is her eyes (with glasses) and a portion of her Teacher at Sea beanie hat. she stands on deck on a clear day and stretches her arms out for the photo — *Me wearing the Immersion (or “Gumby”) suit (Photo credit: Curt Whitmire)*

We practice where to gather, or ‘muster,’ in the event of a fire or abandoning ship. At the very beginning of the cruise, we get right to work with a tour of where to find the lifeboats, how to deploy them, and then we get to the drills.

Recently, I had the opportunity to learn to use the flares and the line thrower. The line thrower is used for ship to ship transfers or for rescuing someone who’s fallen overboard. Although it is really fun to get the experience to use these devices, it is definitely something that you hope only gets used in training. However, knowing they are there and that everyone knows how to use them makes you feel a bit better if an emergency does happen.

Lisa, wearing very large, thick gloves, poses near the ship's railing and smiles at the camera. in her left hand, over the railing, she holds a lit flare. it's a mostly clear day, and the sky is blue with a few clouds, and the ocean has a few whitecaps. — *I now know how to use the flares! (Photo credit: Alice Kojima-Clarke*)

Trying out the line thrower

We are not on autopilot!!! ENS Sixt and LT Hendrix helping me learn to drive a ship! (Photo credit: Randy Scott)

Music Connections

Communicating with Popoki has a lot to do with acoustics. Listening to her pilot talk about how important the angles between Popoki and the ship are reminded me a lot of preparing for a recital when I was a music education student at UW-Whitewater. As an undergraduate, we had several performance requirements per semester. For solo performances, the more experienced music majors would always pass on a very important piece of acoustic information to the new undergrads – always aim the trombone bell at the 3rd exit sign along the stage right wall. Hitting this sweet spot would cause the recital hall to ring, the trombone sound to be dark and full, and the experience to be the best for all who were listening. New trombone majors learned very quickly that this was not a piece of urban legend, but by bouncing the brass sound off of the wall at this angle, it was much more pleasant for the audience than to play directly at their faces.

view of an empty performance hall — *The beautiful Light Recital Hall at the University of Wisconsin-Whitewater – a great place to perform and explore acoustics! (Photo credit: Dr. Glenn Hayes*)

Communicating with Popoki is similar in a way – rather than bouncing her communications off of corners and walls, however, she responds better to the sound waves coming directly at her. She has a sweet spot, too, but it is more about decreasing the angles. This is a much more efficient method of communication for her, because she does not care about the timbre of her chirps!

Another great moment I really enjoyed during our time together was helping our Chief Scientist Dr. Clarke learn ukulele! I always believe that music is everywhere, and Dr. Clarke proved that theory again for me by bringing her ukulele along on this cruise when she heard the Teacher at Sea was a music teacher! Hopefully she had as much fun as I did!

In the computer lab, Lisa and Dr. Clarke sit in chairs facing one another. Lisa, smiling, leans forward to hold up an open laptop where Dr. Clarke can see it easily. Dr. Clarke watches the screen as she picks at her ukulele. — *Dr. Elizabeth Clarke showing off her virtuoso skills with a little “Hot Cross Buns” (Photo credit: Alice Kojima-Clarke*)

Sounds from the ship today will feature the sound of the ship’s engine outside from the very top deck of the ship.

This is the sound of the engine humming from the Fly Deck. You can also hear the waves, as we are in transit to our next station!

Student Questions

St. Bruno students are fascinated by sea creatures, and they have sent me on a quest to learn about the octopus. I think they will be very excited to see this picture and learn about the deep sea octopus!

underwater image of the seafood showing many brittle stars and some corals. in the lower right, there is a sponge, which since it is viewed from above appears as a white ring. inside the sponge, an octopus is curled up - we can see one eye and several tentacles — *Look at the octopus curled up in a sponge in the bottom right corner. You can see the octopus’s eye sticking out! (Photo credit: Popoki*)

Final Notes

The NOAA Teacher at Sea Program is an incredible opportunity for any teacher. As you can see, you do not need to be a science teacher in order to apply. There are so many connections to be made with the ocean, and students get really excited about learning through their teacher’s experience. Applications for the program will open soon. You can find more information here. Thank you so much to the crew of NOAA Ship Bell M. Shimada, the EXPRESS Scientists, and the NOAA Teacher at Sea program for this opportunity. What an incredible experience!

September 2, 2024September 2, 2024

Lisa Werner: Popoki Goes to Sea, August 30, 2024

NOAA Teacher at Sea

Lisa Werner

Aboard NOAA Ship Bell M. Shimada

August 29-September 13, 2024

Mission: EXPRESS Project

Geographic Area of Cruise: Pacific Coast, near Oregon

Date: August 30, 2024

Weather Data from the Bridge (Daisy Bank)

Latitude: 44.37 º N

Longitude: 124.44º W

Wind Speed: NW at 3.17 knots

Air Temperature: 15.7° Celsius (60.26° F)

Conditions: Foggy

Science and Technology Log

Today was the first deployment of the autonomous underwater vehicle (or AUV) for this sailing. The AUV’s name is Popoki ‘Eiwa (which is Hawaiian for ‘Cat Nine,’ and refers to Popoki’s catlike stealth, and the fact that this is the ninth one of this class of AUVs). There was a lot of prep work done yesterday to make sure Popoki was ready for her first outing for this trip (though she has had close to 300 deployments, according to Chief Scientist Dr. Elizabeth Clarke).

Crewmembers on the deck of the ship surrounded a large piece of scientific equipment suspended above the deck's surface by a cable. It is made of two yellow cylinders, each tapered on one end, mounted one above the other by metal beams. There is propeller mounted vertically midway across the front metal beam. There is another propeller mounted horizontally atop the lower cylinder. We can also see instrumentation, a red flag sticking up out of the bag, the NOAA symbol and the name Popoki. Crewmembers wear hard hats and float vests or life vests. — *Preparing to deploy Popoki*

An autonomous underwater vehicle (AUV) is unique because it is not tethered to NOAA Ship Bell M. Shimada in any way. The AUV must be programmed to do what the scientists want. The advantage of Popoki over other submersibles is that Popoki hovers a few meters over the ocean floor, so it can handle rocky terrains better. While underwater, Popoki takes pictures of the ocean floor every few seconds, allowing scientists to see fish, coral, and the marine habitat of the location.

Images from Popoki

underwater image of what must be corals - a few small fish swim nearby — Small fish swim among the deep-sea corals

underwater image of a skate swimming across sandy bottom — A skate swims along the ocean bottom

underwater view of an orange sea star with as many as 22 arms, on sandy bottom — An orange sunflower sea star

underwater view of a striking orange and pink fish, probably a rockfish of some sort, above ocean floor with some rocks and corals — A rockfish

underwater view of a mottled brown fish resting on a rocky bottom, near a white coral — Fish spotted near the ocean bottom

The first thing necessary for Popoki’s deployment today was to have a Green-Amber-Red (GAR) Daily Risk Assessment Meeting. This took place on the bridge, and Chief Scientist Dr. Clarke and her science team met with Commanding Officer Gibson and her ship crew. Both parties looked at current conditions and the necessary actions of the deployment, mission, and recovery of the AUV. They assessed categories such as resources, weather, and mission complexity to determine whether conditions were acceptable for a deployment today. Everyone communicated questions and concerns about the mission objectives. In the end, it was decided the mission was an Amber level – meaning to use extra caution. This is normal for the first deployment of a sailing, as there are new crew involved who have never dealt with Popoki before. Also, during the dive, the ship needs to be able to stay in a position to communicate with the AUV. The risk assessment served as a reminder to everyone to pay very close attention to everything that was going on and to communicate effectively and efficiently to get the job done.

After some deck testing, it was time to get Popoki to sea. She was hoisted off of the deck using the ship’s winch and side a-frame, and then gently lowered to the water. It takes many crew members to make sure that the 600-lb. Popoki does not get hurt or that she does not rub along the side of the ship.

Popoki was deployed a little before 10 am, and recovery started around 2:30 pm. She has a very busy work day (the subsequent dives for our trip will be around 7 hours), and Jeff Anderson, AUV pilot and scientist, will have a busy evening of analyzing the pictures she is bringing back. The recovery process is fascinating to watch, as it is an intricate dance of ship control by the highly skilled bridge of the ship, and the scientists and deck crew with impressive skill trying to wrangle the AUV with lines, hooks, and the winch. No easy feat for sure, though they certainly made it look less difficult than it was! Popoki will be deployed every day of this sailing, weather permitting.

view over the ship's railing of the autonomous underwater vehicle in the water on its return. from the surface, we can only see one of the two yellow cylinders that make up the instrument's body. We also see the red flag mounted on the back. Crewmembers farther down the deck extend hooks on poles, connected to winch cables, toward the swimming AUV. The ocean is fairly calm, and gray, reflecting a foggy gray sky. — *Hooking the Popoki to bring her back*

view down the ship's railing as crewmembers wearing hard hats and life vests use hooks on poles, and cables, to hoist the autonomous underwater vehicle out of the water; in this view it is suspended just above the ocean surface, dripping water. The ocean is calm and gray, reflecting a gray foggy sky. — *Hoisting Popoki back onboard to the ship*

Popoki does not just bring back pictures – she has a sophisticated collection of sensors that will graph the salinity, dissolved oxygen, and temperature, along with graphs that monitor the use of her propellors, battery usage, buoyancy, etc. It is really impressive to see all that she has encountered during the entirety of her dive.

photo of a computer screen displaying a graph labeled "Depth vs Time," with Mission Time as the x-axis and Depth as the y-axis. There is a dark purple line and a green line displaying the data. — Data showing Popoki’s different depths over the time of her dive – notice how many peaks and valleys occur – that’s a lot of shifts for ocean floor terrain, telling us it is very rocky and a lot of terrain changes below Popoki

Personal Log

I really enjoyed being a part of the risk assessment meeting and noticing how important it was that every person involved in the deployment, operation, and return of Popoki had all of the information of the day’s agenda. Every aspect of the day’s goal was planned, with every person aware of which portion he/she was responsible for. Although I don’t necessarily need to assess the risks involved with holding a music concert, the coordination of communication reminded me a lot of how big music events run at our school. Every person in our school – teachers, students, custodians, parent volunteers – all have a very important role to play in the success of the concert. The risk assessment for Popoki gave me a new perspective on how to best address all of the moving pieces necessary to communicate the needs for the concert, and the involvement of everyone in the success of the event!

Additionally, the pictures that came back from Popoki were so impressive to see, even while unedited (the computer runs a color-correction program). It is truly remarkable how the majority of people can be floating above 300 meters of water and never know what is directly below us! It was like looking at pictures from an oceanography documentary, except knowing that I was right above what was being shown on the screen. Seeing something that so few people get to see while being in the location the pictures were taken is an incredible experience! I am just in awe!

view over a man's shoulder of the laptop that he is working on. The laptop displays a black-and-white image of coral. The man sits at a metal desk or bench and uses an attached computer mouse with his right hand. In front of him is a cloudy window through which we can see an exterior ship railing. — *AUV Pilot and Scientist Jeff Anderson looking at initial images from the AUV.*

Music Connection

I did not talk about this up above, because I really wanted to discuss this here in the Music Connection: How do you think scientists on NOAA Ship Bell M. Shimada communicate with Popoki?

If you guessed through the use of sound, you are correct! The technology is similar to that of a fax machine – a computer translates the programming from the scientist into a series of audio tones that are sent to Popoki. Popoki communicates back with a set of digital signals. It is a complicated oscillation of pitches in a variety of rhythms from the scientist doing the programming, a handoff period (because you do not want both the ship and Popoki transmitting at the same time), and then tones of different durations from Popoki responding with what actions she is doing (confirming the commands being followed, documenting images being recorded, recording position, etc.).

This is a sample of the audio coming from Popoki during her testing on the deck of the ship before deployment.

Student Questions

The students I teach made up a list of questions for me to get answers for them, which I called “Homework for your Teacher.” One of the questions they asked was if there were any jellyfish in the area I was going to be. After my visit to the aquarium, I learned that Moon Jellyfish were in the area. Today, while I was on the bridge, Ops Officer Lt. Jaime Hendrix showed me a jellyfish that we could see in the water, as it was near the surface. It was incredible to see a jellyfish outside of an aquarium, and I was impressed I could see the Moon Jellyfish all the way up on the bridge!

May 7, 2016August 21, 2021

Nichia Huxtable: Life on board, you won’t be bored!, May 6, 2016

NOAA Teacher at Sea

Nichia Huxtable

Aboard NOAA Ship Bell M. Shimada

April 28-May 9, 2016

Mission: Mapping CINMS Geographical area of cruise: Channel Islands, California Date: May 6, 2016

Weather Data from the Bridge: 2-3 ft swells; storm clouds over land, clear at sea

Science and Technology Log

Dismantling the REMUS 600 AUV for its trip home — Goodbye, AUV. Until we meet again.

The AUV is no longer my favorite thing on Shimada. As I write this, it is being dismantled and packed into shipping boxes for its return trip home to Maryland. To keep a long, sad story short, the AUV had a big electrical problem that was fixed, but when the scientists turned it on for a test run, a tiny $6 lithium battery broke open and oozed all over the motherboard. Game over for the AUV. So now my favorite thing on Shimada is the ice cream.

Personal Log

Enough about science and technology for now. I bet you’re really wondering what it’s like day in and day out on board Shimada. Well, my intrepid future NOAA crew members, this blog post is for you! We’ll start what’s most important: the food.

Dinner options onboard Shimada.

Cooking in the galley

Lunchtime!

Need some tea

Breakfast, lunch, and dinner are all served at the same time everyday. The food is prepared in the galley and everyone eats in the mess. Beverages, cereal, yogurt, fruit, snacks, the salad bar, and ice cream are available 24 hours a day, so there is no need to ever be hungry. Not all ships are the same, however. In one of the many anecdotes told to me by master storyteller Fabio Campanella, an Italian research ship he once worked on served fresh bread and authentic pizza everyday…sign me up for that cruise!

DSC_0470[1] — Unlike the AUV, the ice cream freezer never disappoints

Next, you’re probably wondering where everyone sleeps. Sleeping quarters are called staterooms and most commonly sleep two people, although larger staterooms might sleep four. Each stateroom has its own television and a bathroom, which is called a head. As you can see in the photo, the bunks have these neat curtains that keep out the light in case your roommate needs to get up at 1 a.m. for the night-shift.

Stateroom on NOAA Bell M. Shimada

Stateroom on NOAA Ship Bell M. Shimada

Stateroom hallway on NOAA Ship Shimada

"Working — Working in the Acoustics Lab on *Shimada*

The Shimada has lots and lots of work and storage rooms, each serving a different function. There is a wet lab, dry lab, chem lab, and acoustics lab for doing SCIENCE (woohoo!), as well as a tech room for the computer specialist (called an ET), storage lockers for paint, cleaning supplies, and linens, plus other rooms full of gear and machinery. There’s also a laundry room, so you can take care of your stinky socks before your roommate starts to complain!

Gear storage on NOAA Sip Shimada

Dry Lab on NOAA Ship Shimada

Laundry room on NOAA Ship Shimada

Electrical technician’s office on Shimada

Computer room for Shimada’s crew

An office for a NOAA Corps officer on Shimada

Trash on board is separated into recyclable bottles and cans, food waste, and trash. The food waste is ground up into tiny pieces and dumped in the ocean outside of the sanctuary, while the trash is INCINERATED! That’s right, it’s set on fire…a really, really, hot fire. Ash from the incinerator is disposed of onshore.

Another important part of the ship is the bridge. Operations occur 24 hours a day, so the ship never sleeps. Officers on the bridge must know what is happening on the ship, what the weather and traffic is like around the ship, and they must make sure to properly pass down this information between watches. The bridge has radar to spot obstacles and other ships, a radio to communicate with other ships, and a radio to communicate with the crew and scientists.

"Looking — Looking for wildlife on the NOAA Ship *Bell M. Shimada*

3rd Engineers E. Simmons and C. Danus

Painting the deck of NOAA Ship Shimada

Last, but not least, is the lounge that comes complete with surround-sound, a big screen TV, super-comfy recliners, and about 700 movies, including the newest of the new releases.

Did you know?

A female elephant seal was once recorded diving underwater for two continuous hours (they usually stay underwater for 1/2 hour); the deepest recorded dive was by a male and was 5,141ft.

Stay tuned for the next post: Multibeam? You Mean Multi-AWESOME!

May 2, 2016August 21, 2021

Nichia Huxtable: AUV, Why Won’t You Work? May 2, 2016

NOAA Teacher at Sea
Nichia Huxtable
Aboard NOAA Ship Bell M. Shimada
April 28-May 9

Mission: CINMS Mapping
Geographical area of cruise: Channel Islands, California
Date: May 2, 2016

Weather Data from the Bridge: 17-20kt winds; clear skies; 0-1ft swells

Science and Technology Log:

There is a lot of amazing equipment on board Shimada, but my favorite, by far, is the REMUS 600 AUV. Really, it should be everyone’s favorite. What other piece of equipment can you release in the middle of the ocean, have it swim around for a few hours collecting data, then have it ready and waiting for you in the morning? I’m pretty sure my laptop wouldn’t be able to do that if I threw it overboard (although, on a few occasions, I’ve been tempted to try).

On Shimada’s mission, the AUV is used when scientists need detailed, high-resolution imaging of deep water areas or areas of special interest. The ship’s ME70 multibeam sonar can map the seafloor up to 350m deep, whereas the AUV can map as far down as 400m. Now remember, this is an AUTONOMOUS Underwater Vehicle; this means that you are literally dropping it off the side of the boat, leaving it to propel itself along a pre-programmed route, then, hours later, returning to a set location with the hope of seeing your million-dollar robot pop back up to the surface to be retrieved.

DSC_0730[1] — The programmed route of the AUV, including satellite and GPS call points (circles) and return location (yellow square)

DSC_0808[1] — The AUV has returned to the *Shimada*!

There is a lot that needs to go right in order for this to happen. In the REMUS 600, there are three separate systems that must all function correctly in order to successfully complete its mission. The navigational system includes an Inertial Measurement Unit (IMU) for pitch, roll, and heading compensation, a Doppler Velocity Log (DVL) for speed over land measurements, GPS for location, and processing software. The communication system includes a micromodem to receive status messages while AUV is up to 1500m away, an Iridium satellite communications system, and, of course, Wi-Fi. The sensors include multibeam sonar, obstacle avoidance sonar, a depth sensor, and a CT (conductivity, temperature) sensor to analyze sound speed for beam formation.

If these systems aren’t working correctly, there’s a good chance you’ll never see this AUV again (which would make a lot of people very unhappy). Basically, all these systems ensure that the AUV stays at a specific height above the seafloor (around 75m), runs a specific course that you programmed, and collects data for you to analyze when it returns. Every hour or so while it’s running its course, the AUV rises to the surface, makes a satellite phone call to check in with Shimada, then goes back down to continue its data collection. When it’s done with its course, it runs in circles (think underwater donuts) until the ship returns and the scientists call it back up to the surface where it can be retrieved.

DSC_0904[1] — The inner workings of the REMUS 600

Remember how I said that all the systems must be working correctly in order for the AUV to successfully complete its mission? Well, this first launch and retrieval went off without a hitch, but it turns out something went wrong with the data collection (as in, there were no data collected after the first 45 minutes). The scientists are once again on the phone with customer support to try to figure out what went wrong.

On the bright side, there are far worse things that could have gone wrong: the AUV successfully ran its course, checked in with the ship, and came up to the surface at the time and place it was supposed to. That doesn’t always happen, which is why the AUV has an “If found, please call this number” sticker right on top of it. Just like what’s written on your retainer case…except your retainer didn’t cost one million dollars.

Personal Log:

Even though it seems like the hours are filled with troubleshooting and problem solving, there are still many things going our way. The ME70 and EK60 have been successfully running all day, the weather is fully cooperating with calm seas and beautiful skies, and, last but not least, dolphins decided to play right next to the ship. Bring on tomorrow!

Dolphins around San Miguel Island. Always a crowd pleaser!

Words of the Day: AUVs and ROVs. Autonomous Underwater Vehicles are pre-programmed and complete their mission without supervision. Remotely Operated Vehicles are connected to the ship by a cable and are directly controlled by a human operator.

June 5, 2015August 21, 2021

Heidi Wigman: Underwater Acoustics, June 4, 2015

NOAA Teacher at Sea
Heidi Wigman
Aboard NOAA Ship Pisces
May 27 – June 10, 2015

Mission: Reef Fish Survey
Geographical area of cruise: Gulf of Mexico (26°33.512’N 083°43.064’W)
Date: June 4, 2015

Weather: 82° @ surface, NE winds @ 5-10 knots, seas 0-2 ft, chance of showers and Tstorms, average depth 75m

Science and Technology Log:

The science behind underwater acoustics play a huge role in the operations of the Pisces. Each of the five survey types (CTD, camera rig, sidescan, bandit reels and AUV) need accurate data about the depth and contours of the ocean floor. Most people are familiar with the idea of how radar sends out a “ping” and waits for a return in order to determine a distance of an object. This is not a new, or even a human invented design — bats, dolphins, and some whale classes use “echo location” to get information on food sources and predators. As a pulse is emitted from the transmission source, it travels through the water at a certain speed, and as it encounters objects, returns as an echo.

ping transmit and return — “ping” transmit and return provided by C. Thompson

As data is received, it can be read as a function of voltage output to time in seconds, but this type of information generally is not useful for operational purposes. This two-way travel data needs to be converted to provide a graphical representation of the contour of the ocean floor, and the location of objects in the water. An algorithm turns all of this into usable data, that gives the viewer a depiction of what is under the vessel, and at what depth.

sonar imagery provided by Charles Thompson — sonar imagery provided by C. Thompson

echosounder depth measurement, provided by C. Thompson

In order to get depth (Z), you need to know about how fast sound travels (c) – and this can vary with environmental factors such as temperature, salinity, depth, turbidity, etc. The third variable is the time (t) in seconds that it takes from ping to return. The formula that is used to calculate the depth is Z = c*t/2.

During our cruise, the sound speed value we are using (1540 m/sec) is the mean value of the measured sound speed vs. depth profile, with slight margin of error on the minimum values. Therefore, any miscalculations based on the constant will provide a reading more shallow, rather than more depth.

The EK60 echosounder emits a frequency of 18kHz, with most of the power in an 11° conic sector directed downward(see diagram). In order to find the area covered by the pulse, we first need to find the diameter (d) and the vertical depth (Z) or the max beam range (R).

sonar effective area; provided by C. Thompson

Math question of the day: What is the area covered by one sonar ping from the Pisces? If you know that your vertical depth is 75m, and the bisect on the beamwidth (11°) angle, use some trigonometry to help find your radius. [Tan 5.5 = r/75]. Once you have the value of r, use the formula for area [A=3.14(r*r)]

Previous Answers:

Trigonometry of Navigation post: 18 m/s @ 34°SE

Bandit Reels post: about 14.6 nautical miles

The STEM of Mapping post: layback = 218m, layback w/ catenary = 207m

Coming soon . . . A trip underwater – A closer look at NOAA dive tables