Embedded - 363: Squishy Nature

Episode Date: February 26, 2021

Alana Sherman of the Monterey Bay Aquarium Research Institute (MBARI, @MBARI_News) spoke with us about engineering for deep sea environments and jelly creatures. Alana’s MBARI page notes that she worked on DeepPIV and the Benthic Rover. She is also a part of the BioInspiration Lab. Larvaceans: image search, short video, or (my favorite!) the long video. It is probably too late to purchase tshirts but… in case it isn’t, here is the link.

Welcome to Embedded. I'm Elysia White, alongside Christopher White. We are excited to talk ocean engineering and underwater projects. Our guest this week is Alana Sherman, an electrical engineer and project manager at the Monterey Bay Aquarium Research Institute. But before we start the show, I want to remind you that if it is still February 2021, you can still get t-shirts, but you're running out of time. Hi, I was someone who went from math to engineering and always had a desire really to be involved with science, but not doing science on a day-to-day basis. And so I was interested in developing scientific instrumentation,

and I kind of landed at MBARI, where I could build scientific instruments for studying the ocean. Okay. So of course, I have many questions about the instruments and about the ocean, because that's how I roll. But first, we to do a lightning round where we ask you short questions and we want short answers. And we'll try not to ask how and why. Have you ever pet a penguin? No. Do you have a favorite body of water?

A Sargasso Sea. What do you consider to be the weirdest animal? Oh, that's a good question uh maybe um that i have to remember the name is a fish where it looks like it has eyes in front of its face but it's really at the top of its head looking up it has a transparent head oh with the brain you can see yes yeah yeah that's a good answer do you think europa is a good candidate for life my naive opinion is it's a better candidate than a lot of other places we could get to uh if you could teach a college

course what would you want to teach i would would want to teach an engineering project course where you're actually building something and you have something to show by the end of the course. Do you have a tip everyone should know? I don't think I wish I did, but I couldn't think of one. That's fine. Okay, so you work at MBARI, which is Monterey Bay Aquarium Research Institute. And you've been there for a while. How long? I've been there for 17 and a half years. Wow.

Yeah. So what keeps you there? You know, I was just reflecting this morning on something someone told me in my first couple years. And he said, you really have to love the work. And that's the glue that keeps you there. And Ambari was started by David Packard, who had this vision that we could really take advances in technology and use them to learn more about our understudied oceans. And I really love that work. And that's, that is the glue that keeps me there. I love, I love exploration and discovery. I love the satisfaction of building something. But I love building something that I can then see the product from and gain more insight to the ocean. Is it more about the science or more about the engineering that keeps you engaged?

Well, I think that I am maybe in the minority of engineers that for me, I really like answering the science question and I'll build as simple or complex an instrument as required to do that. So I think that I'm more driven by scientific discovery, even though I'm definitely an engineer, but that's what drives me. I saw you'd written a paper or your name was on a paper that involved mucus webs. Could you tell me more? I would love to. This is a work that was really led by Connie Katija, who came to MBARI as a postdoc. And she, I was one of her two mentors. And we were looking at these larvaceans, which is what you're mentioning with the mucus web. And larvaceans are, they're definitely one of, they've rapidly become one of my favorite animals

because they're so amazing. So it's this tiny animal and it creates this mucus house and it actually creates this both inner and outer house. And the inner house, it also, it sort of looks like a brain or like a set of lungs. It's this very complex structure and it's made out of mucus and it just basically like blows it up. And then it has this larger surrounding mucus, the outer house of mucus. And that it collects all this, like what we call marine snow, all these particles in the water. And it's basically like this animal works like a particle condenser. It's basically just taking in all these particles, filtering, using its inner house to filter them, and then eating it. And once its houses get

clogged, it just dumps them, swims off, and like repeats the same thing over and over again. It's fascinating just from a biological perspective, but it actually is very impactful from a perspective of moving carbon from the upper parts of the water column, the top layer of the ocean to the bottom. we call them sinkers and you have this particle rich uh mucus clump now that's reaching the sea floor and providing food for organisms that live down there um so it's a a um interesting pathway an important one from a surface to the sea floor for carbon so i'm trying to visualize this at first i was thinking they were anchored to something, but you're saying they're just free flow. They're midwater. And I encourage anyone to go and look up a larvacean because if you saw it, you have to find a picture where it calls out what is actually the animal versus the housing, because I think often you would not believe that the inner house is something that an

animal could blow up in an hour or that an animal could just make that out of mucus. Wait a minute. They make them in an hour? I mean, because they're pretty big. They've been observed. Oh, yeah. The inner house, I think it blows up within around an hour or so. I know it's totally unbelievable. And they, in addition to taking carbon down to the bottom of the ocean, they also collect plastics. They, well, so Kakani did an experiment where they looked at whether they would take in plastics. And yeah, so microplastics, of course, like small particles. But to these, yeah, so they can carry small particles, microplastics from the surface waters to the seafloor for sure. Why are these important? I mean, yeah, okay, so when they release their snot houses, it goes to the bottom of the ocean.

But are these important in other ways? Well, I think they are like super pumpers. Like they filter this huge amount of water over time. And then they take all these, you know, nutrients that are in that water, and then they move this to a completely different place in the ocean. So it's sort of important the same way DoorDash is to us, right? Like they're delivering food to somewhere that doesn't is very food poor. And that is that is actually super important to the ecosystem. You know, it's important to understand how carbon moves through the ocean. And it's important to understand how the surface what's happening on the surface affects the ecosystems. The thing about larvations and, you know, most of what we know

is from the work Bruce Robeson has done, he's another scientist at MBARI, is, you know, they can, you can go through periods of time where there aren't, there are many, and then there can be a time where it's just like all you can see. And so, you know, it's one thing when you have one of these animals doing it, but when, you thing when you have one of these animals doing it, but when, you know, you have tons of these animals out there, it makes a really significant impact and, you know, on these ecosystems. So. They look kind of like jellyfish. I mean, I guess maybe that's just their squishy nature, but they aren't at all. They're actually closer to us.

Well, you know, they are. I don't know about their main body. I don't know much about the swimming animal. I don't know that it might not be gelatinous. So is it a chordate? It is a chordate, but let's talk about the engineering parts. Don't let me get too distracted with the squishy animals because it's really easy for me to. Okay. So the animals are cool, but it's not like you can just pull them up in a net because they're mostly mucus.

Or at least the houses are. You can't see them. So how do you, do you just wander around with a camera at the bottom of the ocean or mid-ocean and hope to catch one? observations that we've done at MBARI have been made by ROVs, remotely operated vehicles that are underwater vehicles tethered to surface ships that have, you know, very high resolution cameras and tons of lights on them. And you can sit and watch one and learn a great deal. The work, the project that Kakani and I worked on, which is called DPIV. PIV stands for particle image velocimetry, which is a fancy name, but basically it's a technique that fluid mechanics, mechanicians use to look at how a fluid flow,

and they do it by using particle motion to sort of elucidate fluid flow. Uh, and so Kakani, um, had the idea to try to do this in the ocean, which is pretty tricky because it involves focusing a laser sheet on, you know, where the fluid motion is that you're interested in. And, um, we do this from the ROV. And so you have the ROV moving, you have currents in the midwater, and you have an animal moving in a completely different way. So it's a challenging application. But we're able to do two things with that instrument,

we're able to look at the fluid flow. And then we're also, Kakani had the idea to basically like scan through the laser sheet through the animal and then use it kind of like a CT scan where you take each image and you can recreate the 3D structure. And you mentioned jellyfish and gelatinous animals. And the thing about recovering them is very difficult. You know, they often are super, super fragile. And so by scanning them, you're able to see parts that are, that would not have survived. So you get a much better idea of what their actual body morphology is like. So we try to use things like this to study these animals. But it's underwater.

And that presents a large number of hurdles. I mean, I CT scan, I understand that, but... I don't. I mean, when I think about it as a bunch of x-rays stacked together. Sure, okay, yeah. Yeah. don't i mean it kind of when i think about it as as a bunch of x-rays stacked together sure yeah yeah but this this particle imaging what's the v for yes velocimetry see they make it sound so complicated that anyone couldn't understand it but it's just velocimetry. It's just looking at motion. It's the velocity of fluid. It sounds impressive.

It does. But these ROVs have to work in an environment that is more hostile than most terrestrial environments. Yes. It's very, you know how I describe it? It's very dynamic. It's a very dynamic environment. And in everything you try to do with respect to the animal is something that is really only made possible by the fact that we have extremely skilled ROV pilots, skilled and patient, because it takes great patience to wait for that animal to kind of be in the perfect position and the vehicle to be in the perfect position to get the best data you can.

How deep are we talking about? Well, that's a good question. So this particular, well, the instrument we built can go to 4,000 meters, but the larvaceans, they are, I want to say like, they're usually like around 200, 300 meters deep. That sounds incredibly deep, but when you put it against 4,000 meters, it doesn't. You know, most of my career I've done really deep stuff.

So to me, it's super shallow. But it doesn't really, you know, a lot of the challenges are, you know, going deeper doesn't always pose that. It poses a lot more expense often, but it's maybe not that much more challenge. I've done some laser scanner work at a couple of places, both medical and the past. And I just wondered if you'd be willing to describe the device a little bit, if you're willing. Yeah, I'll do my best. It's basically, it's just a, I think our first version was a one watt laser and then optics to turn that laser beam into a sheet. And so it's sort of, yeah, you can imagine sort of coming out of a focal point, this sheet,

maybe, I don't remember if it's like 70 or 80 degrees. And then, okay, so here's like where it gets tricky is so then we have a camera. And so you can imagine if you imagine the ROV has this, you know, robotic manipulator arm, something like that. There's the, what we call the probe head, which is the housing that has the optics for the laser. And that's at a 90 degree angle to the camera. And so basically you're, you're imaging right, you're imaging, you're focused right on this laser sheet. Kind of at a right angle to how it's being scanned exactly exactly and so that's all the easy part the hard part is getting the animal in the laser sheet because the sheet is i know um less than two millimeters maybe like a millimeter thick um so it's a very thin sheet because you don't want blurring or smearing, I guess is a better way of saying it. So it's a very thin laser sheet.

And that's where the challenge comes. How big of an area can you put this laser sheet over? Now you're going to ask me. I mean, I don't need to know like precision. It's like... I'm trying like... A meter square, three meters square? A couple inches wide.

No, not three meters squared. Less than a meter squared. Trying to remember what the box is. I mean, I would kind of envision it as like maybe two 11 by 17 pieces of paper put together. The power of the laser definitely diffuses the further away you get, you know, so there is a sweet spot. A one watt laser in free space. Oh, that's going to go to the moon, but it's underwater. Yeah.

Yeah. It seems like engineering for underwater, particularly when we talk about 4,000 meters, which is like the average depth of the ocean is 3,800 meters. Yeah. When I think about space, it's like, okay, right now I am at one atmosphere. That's how much pressure the air puts on me. And then if I were to go to space right now without any protective covering, bad, bad things would happen to me. But if I went to a depth of 5,000 meters, which is more than we were talking about, but yeah, well, I guess 4,000 meters would be approximately 400 atmospheres. That's a much larger difference than here to space

yeah you wouldn't want to go there without any protective gear yeah the pressure is i mean it's it's sort of i was trying to explain it to my son's first grade class and i think we sent something, they made little styrofoam cups and we sent them down on the ROV to like, I don't know if it was 3000 meters, something like that. But it really like the pressure was like, you know, if you had an elephant standing on a quarter, like that was whatever, if it was like 5,000 PS pounds per square inch, something like that. I mean, that was sort of the equivalent. So it's a lot of pressure. And it's cold. How do those things affect the projects you build?

Is it mostly mechanical or does it also affect the electronics? So in electronics, you basically have a couple of choices if you're building something to go deep you can make what we call pressure tolerant electronics which are going to be in a housing that's filled with oil that is basically at approximately the same pressure as whatever the ambient pressure is and that does okay for a lot of, a lot of things, but it doesn't work well for like, you couldn't, you know, things that have a void, like electrolytic capacitors or something like that. So, um, the alternative is to build these, you know, one atmosphere housing.

So housings that withstand that pressure. And, um, and so based on what you're doing, that that's sort of the way the pressure affects designing electronics. Now, cold has a different set of issues with, um, I think the ones that have been the trickiest are like cold starting things that don't function the same way when they're cold. Like, you know, I think we had some concerns, although I think it's mostly worked out fine, like with the laser, right? Like things that need like a certain amount of a certain to be at a fixed temperature to run stably, you know? And so you're going from sitting on a deck, sometimes in the sun and kind of baking to this very cold environment.

And sometimes things that have cold soak too long can have problems. And you can have all sorts of weird problems. Like they had some, it was like some grease on it that like if it cold soaked long enough, the motor couldn't, it became too sticky and the motor couldn't overcome the friction. You know, but those are very tricky ones to figure out. It's easy to figure out problems that happen under pressure or under cold temperatures individually. But sometimes you have problems that happen only when the cold and the high pressure happens, and those are tricky to recreate in the lab. How do you know which components aren't solid? I mean, like electrolytic capacitors, are there other...

Is there a digikey search term for... Yeah, what's the parametric search term? Only from my colleagues telling you know we just know from our experience and we you know we'll test things before you know we just put them in our we have a pressure vessel that we can um i don't know how you might even it goes way more it goes more than 6 000 psi but usually for the stuff I do, that's kind of what I would test it to. And so that's how we figure it out. And, you know, there's a lot of kind of word of mouth of what things don't or can withstand

pressure. I mean, that's sort of the more when we find something, we're like, oh, this, you know, crystal can, you know, take pressure and stuff like that. So actually I just had this experience at work because we, um, we're basically like a poxing a section of a circuit board to withstand the pressure because there's one component that was a problem. And someone told me, well, I heard so-and-so found another component that's pressure tolerant. So it's all, it's a lot of word of mouth. It seems like all sorts of things. It's insidious, right? There could be things you don't expect, like even a chip, maybe an IMU or some sort of MEMS thing, right? They have to have little

motions. There must be a void in there somewhere, right? Yeah. You know, I mean, in truth, if I can avoid pressure tolerant electronics, I certainly would prefer it for those reasons because they don't always fail right away. We had this interesting case where it was a commercial motor controller. It was just an off-the-shelf motor controller, and we'd been using them for years. And then suddenly, we had the ones that that started failing and they had changed a component. And, like, they don't care. They're not sending it down in the ocean. But for us, it suddenly took a part that was working and, you know, made it not work anymore.

So, yeah, they can be pretty insidious. Does that mean you have to kind of ignore the environmental ratings on some components and just hope for the best or? Oh yeah. You throw out the warranty pretty much right away. I mean, yeah, we're like, yeah, we, we pretty much are often getting into whatever we buy, you know, and, but you know what I found, um, often I'll get in touch with, if you can, if you can get in touch with these companies, I think they generally find our application interesting and different and they're super helpful. Um, for the most part, I mean, we're very, you know, we're never going to buy tens of thousands of things. So we're not really,

there's no economic value to being helpful, but they tend to be in it. And once you kind of get someone on the inside, you can get pretty far towards solving issues. One of the projects you worked on was the Benthic Rover. Could you tell us about it? Oh, yes. We always joke that the rover was my first baby. The Benthic rover was a project that actually came to MBARI with a scientist. Ken Smith is a Benthic ecologist. Wait, wait, wait. Define Benthic first. Oh, sorry.

You know what? Actually, I'm glad you said that because the first day I toured MBARI, people kept saying Benthic. And I finally was like, what does Benthic mean? It means the seafloor. He's a seafloor ecologist and um he had built a previous seafloor rover an instrument that drove along the seafloor making measurements um which i can describe in more detail and um he was building a new one right at the time that he moved from scripts to embari and i you know naively i kind of imagined this little thing that could like sit on the floor of my office and you know i could test out driving around my office um and then i saw that it's like

roomba right yeah but actually it's like the. It's more like the size of an SUV in reality. So I was I turned around for a few days every year, but it's been down there since 2014. And what it does is it takes measurements that they call sediment community oxygen consumption. So it has two chambers, which can be sealed, that have oxygen sensors in them. And it's basically measuring the oxygen that's consumed by the organisms that live in the top layer of the sediment. And I sort of, in addition to this, it will, so it will make that measurement for two days and then it will lift up the chambers. It'll drive 10 meters while taking images as it drives. And then it repeats the same thing over and over again. And we also have other instruments there that we call sediment traps, which are commercially available instruments love free food, and if you had an oxygen sensor in a closed room, and you sent out an email that there was free pizza, and you close the door, like, if someone studied human physiology, they could, like, learn a lot about how many people

were in that room eating the pizza. And, you know, if you knew how much pizza every person ate, you know, roughly, you could learn about how much food was coming down. And that's like a kind of silly but not totally inaccurate example of what we're trying to do. We're trying to look at how much food is getting to the seafloor and how it's being consumed. Isn't that very dependent on luck and what's happening above them? I mean, it seems like I've heard about whale falls, which would be when a whale dies and goes to the bottom. Yeah. That creates a whole new community.

But even like when we have here in the Monterey Bay, we sometimes get giant squid blooms or even sardine blooms. Or larvacean blooms, yeah. Or salt blooms, yeah. And the benthic rover might enter an area of that and it would be drastically different than its previous measurements? Or how does it work like that? That's actually a great question. And it kind of gets to the heart of why the benthic river sort of had to be the way it is, is that it's like I say, like the deep ocean is really interesting, but only very occasionally,

which is to say that there's not a whole lot going on, but then every, like you mentioned, every once in a while you get these, what we call them is pulses. You have this large amount of food coming down and they, you know, it can be from blooms. It can be all sorts of things like that. And like, for instance, you know, like salps, we had this case where we saw that there was, you know, on the surface, there are all these salps. Salps are these like little gelatinous animals that form chains. And then they all died and they sunk to the seafloor. And it was like, it was like enough food for the seafloor community. I mean, it was like months worth of food. And so it is a very, that, uh, that way that ecosystem works is you

have these very significant events in between a lot of monotony. And that is why you need kind of these instruments like the Rover that's basically down there all the time. And so you were asking really kind of like, is it very a lot spatially? Like if the rover's over here, is it going to miss something over there? But time too. So my point is that it actually, it seems to vary much more in time than in space. You know, there, I mean, there's probably small variances in space, but in the region that we have a bunch of instrumentation down at, we tend to see the same, even though the instruments are not right next to each other, we tend to see the same things happening. I mean, that makes sense.

And I guess spatially, if you were near a large river, you might see things when you're closer to where the river lets out versus where it's further. Yeah. And, you know, your analogy is kind of accurate for where the rover lives because the Monterey Bay has a submarine canyon and the site where we go to, which is off of Point Conception, maybe like 150 miles. It's kind of beneath the, eventually that canyon sort of fans out and then that's kind of gets to the area where we work. So we are actually sort of at the edge of that sort of submarine river, so to speak. It's weird to think about submarine rivers. When I first started talking to MBARI folks, when we first moved over to Santa Cruz, I just am boggled by the idea that there are rivers underwater. Yeah, I mean, I guess I'm using the word river loosely. I think what's interesting to me about the canyons is like,

and as a geologist, I've worked with Charlie Paul's study, there's a lot of sediment flow. Yeah, so it's a different type of, it has like kind of river qualities in that there's all of this. We were talking before about moving material and carbon from the surface to the sea floor. And these submarine canyons, they're moving things from inshore to offshore in their own dynamic way um but equally importantly so switching subjects a little bit um but staying on the topic of sediment flow yes you worked on instruments to sample sediment flux under icebergs oh yeah could you i mean i'm not sure all those words go together. So could you give me an overview? like these icebergs, or they use the expression like a halo of life, like there was more life

around the iceberg than in the open ocean, if you went a little ways away. And the reason they felt that was probably true is because the ice coming off of Antarctica, as it's sort of those ice sheets, as they drag along the continent, they get soil and earth in them and then they break off, go out into the ocean and they have these nutrients that feed these communities and sort of like the food chain, right? Like you feed the, you know, phytoplankton and that brings the zooplankton and so forth. And so we wanted to see what was coming off the bottom of these icebergs. So I explained to you a little bit before about a sediment trap. A sediment trap is just like a funnel that's usually fixed under the ocean somewhere. And all this marine snow is slowly drifting down.

And you just imagine this funnel is just sort of concentrating it. There's cups at the bottom of the funnel that rotate. And you can set how often they rotate. And so each cup is collecting basically this kind of concentrated amount of marine snow that has fallen for a fixed period. And so we were trying to do kind of a little variant of that, but it had to go under the iceberg, which was a little bit of a challenge. So we used, there are these amazing floats that people have developed that have variable buoyancy

engines. The one we use was developed at Scripps and it was called a solo float. And so basically they have, the float is basically able to change its buoyancy to reach. And you said, cause you could tell it like, okay, go down 200 meters and it'll make itself heavy. And then when it gets to 200 meters, it will make itself neutrally buoyant and it'll just float along at 200 meters until you tell it come back to the surface and then it'll make itself light and it'll come back to the surface um so i i take no credit for any of that i just we just bought those and then we added um sediment traps to them and then we also added upward upward looking acoustics so we could tell if we're underneath the iceberg or not. And so all of this, that was the easy part. The hard thing is

you can't really tell an iceberg which way to go. So there's a certain amount of you kind of put it in the path of the iceberg and then hope that the iceberg stays on that path, which sometimes worked and sometimes didn't. You keep saying marine snow. Yes. That's a polite term, isn't it? It is. It is. For fish poop.

Well, yeah, lots of poop, not just fish. Yeah, it's just, it is. That is a polite term. It's also broken down phytoplankton, you know, it's just particles, you know, of which there's quite a bit of fish poop. That's for sure. But there's also just like algae and stuff like that, that's decomposed and broken down and, and other animals that are smaller than fish that poop, gelata poop, things like that. What, what is jellyfish poop like? I don't know.

And I don't really know if I'm ever going to find out. What kind of instrument would you need? I mean, it doesn't even have to be jellyfish. We can do larvaceans instead. But it just seems like we need a tool for measuring jellyfish poop. Chris is asking me to go back to the benthic rover. I think he has questions about that. No, no, no. Continue by all means. Well, I don't think it would be

that hard to get jellyfish poop. You could just keep a jellyfish in a chamber for a while and eventually it would poop. It probably does more jelly. You know what I find with biologists is that they seem very good at identifying whose poop is what

this is not my area of expertise at all but i just know from the sediment traps which do you know which now we know we could call something else yes yes litter boxes definitely okay so i'm giving i'm being given the signals Yes, yes. Litter boxes. Yes, definitely. Okay, so I'm being given the signals to move on from poop. So the benthic rover, which I don't feel we did justice to. You said it was about the size of an SUV. But you said it mostly just captures this oxygenation. Why does it have to be the size of an suv for something what seems very simple well okay that's it that's a really good question and um so okay

so there's a couple things first um it has to be heavy enough that it can sit on the seafloor and not be blown by the current. But it also has to be light enough that it cannot damage the seafloor. And so one of the ways we kind of achieve that is by having these really wide tracks so that it has the area you're pushing down on is large enough that at every given point, it's not a lot of pressure. So that's part of the mechanical structure. Now, the other part is it takes a lot of stuff to keep an autonomous vehicle running on the seafloor for a year. It takes a lot of batteries, a lot of electronics. There's a lot of instrumentation. And so I think if you were optimizing for the smallest thing you could build you could probably build it smaller

um but you don't have i mean there's no reason to right yeah there isn't a huge you know we had to like you know couldn't weigh more than we could lift it with a crane on the ship and it has to be able to sort of fit into you know the area underneath a frame um but so but there uh there are like trade-offs in terms like it was because we do work in the sanctuary um and i think when we started the project they were kind of worried that we were going to have like this ATV driving on the seafloor, ripping everything up. And so we really had to do some work to show them that like it could drive over a C-pen and it would just, the C-pen would pop back up. You know, it has a very, very light, gentle footprint. And that was important when we were working

in the sanctuary. But that takes space, you know what I mean? It's interesting because the natural thing for me when i hear about autonomous scientific instruments like this is to try to compare them to space probes you know the curiosity perseverance which are giant suv sized rovers on mars but that the requirements and everything are so different right because those have to fit in a spacecraft so so they're optimizing for different things. You don't care about that. They have to operate at a fraction of an atmosphere.

You have to operate at hundreds of atmospheres. So there really isn't that much of a comparison, it seems like. Well, it's interesting. I've had the opportunity to go to a workshop where it was a bunch of you know mars rover people and give a talk about comparing the two things benthic rover to the rover on mars and you know i mean i jokingly say like you know they have it easy because they can talk to the rover like every day right whereas we uh you know once it's in there it's pretty uh you're gonna wait a year to figure out like if it didn't work um but they uh their cost for failure is of course dramatically higher and um

but one of the things it's like yeah someone asked me early on like why didn't you do a legged vehicle and i realized like oh you don, the sediment where we work is, it's super like sticky, you know, it's, it's mushy. And so you really, that, that environment drives the design to some extent. And same, I'm sure, for when they designed the rover on Mars, you know, their environment. But you're right, like having to fit it in a payload, you know, and send it off into space. Those are, I mean, my hat's off to those guys. It's pretty extraordinary what they've done. I mean, it's pretty extraordinary having something at the bottom of the ocean you come by and visit once a year. I know. It Actually, it is. It's funny because I think when people think about AUVs or autonomous

underwater vehicles, they tend to think of what we most commonly deploy, which are these sort of torpedo-shaped vehicles that are in the water column. And they're kind of driving along and they come up. And so our poor rover, I think partly because it's been successful, no one's seen it except for a couple of days at sea. We kind of forget about it, but I don't know. I'm really proud. I'm very grateful my coworkers, at the same time that the rover last came on shore for servicing, I was pregnant with my first child. And so I actually haven't seen it because I haven't been able to go on these expeditions. So we've been apart for six years now, almost seven years. So, but one day soon I have to see it again. But I think it's, I'm very proud of it. I think, you know, to build something that can drive around the ocean for a year reliably and take measurements is, it took us a while to get there. But

it's funny, once it really like became, we out the bugs, and then once it became reliable, it really just kept going. Do you communicate with it through the year? Well, so in the past, I don't know, I'd say three or four years, maybe longer, maybe past five. I'm trying to remember when we started doing this. But we did have the opportunity to send a wave glider, which is a surface vehicle that uses solar and wave energy to drive, to send a wave glider out to where it was deployed and talk to it acoustically. And at first, I was kind of resistant to this idea because I thought, well, if we find out it's not working, or if we can't talk to it and we don't know, it's hard to get ship time. So are we just going to have to sit around for six months worrying?

Is that really going to be better? But actually what we discovered was that one, we could use the acoustics to range to it and give us a position of where it was. And because we knew that the rover should move 10 meters every two and a half days, even just having its position since the last time we visited it was a great metric of how it was doing. And then if the conditions are good enough, we were able to get small amounts of data back. And it actually doesn't take a lot of data to say, okay, this thing's kind of working well. So that was a real huge step forward for us in terms of knowing it was working in the interim between deployments.

For some reason, having things be autonomous to me adds this extra, that's much cooler than, you know, something that's remote controlled. What goes into the electronics in that like it is what kind of processor does it what's his brain okay it has an arm processor and it's its controller is probably i can't even tell you because what i was going to say is that we bought all those components probably in 2006 wow okay okay yeah and it's so we also uh one of my co-workers his name is paul mcgill is an electrical engineer he built a little board we call wakey which just has a pick on it a little uh embedded

microprocessor and And its job is just, so basically everything is sleeping most of the time when we're taking measurements. And the only thing is we have, um, and Wakey wakes up the stack, takes a measurement every 15 minutes and then puts it back to sleep. Um, and so, so that's, that is kind of, of you know wakey's waking up this it's like a pc 104 stack with an arm processor i um on it and that ends up being pretty low power um you could probably do you know you could probably do much better and different now, but we haven't really had the opportunity to revisit it because it's been deployed.

But it's interesting, since this show is about embedded systems, before we made our own Wakey board, we had bought this commercial board, which I think was for battery charging systems. But it basically was supposed to have the same function. And I can't remember what the sleep, the current was when the power was consuming when it was sleeping, but it was supposed to be like low enough not right we started to get closer and closer and we started measuring and it's like a factor of 10 off it's like consuming a lot more energy and so i contacted the company and they're like well we'll go we'll look into this you know and they get back to me and i think like all right they're gonna sell this for me and they're like well we're gonna change our data sheet oh no which is why we built Wakey. Okay. You caught us. I couldn't believe it. I was so sure they'd fix it, but it was not fixable, apparently.

But anyway. You mentioned the wave glider can help locate the benthic rover, was another one of my questions is okay you you put it down you know whatever day valentine's day of of 2007 and you come back a year later to give it its maintenance and it's gone 10 meters every couple, probably in the direction you want, but it doesn't have a GPS. You can't just put a GPS down there. No. So it's just, all right. So where is it? How do you find it? Okay. Well, thanks to the wave glider, it's a lot easier. But what we used to do is, and honestly, I think once it started staying out for a year, that might have been around the time we started doing the wave glider stuff. So that really helped.

But one of the things, one of the keys, I believe, to the rover's success is that it's a very simple vehicle. And in saying that, what I mean is that, like, it's basically we're telling it, you're going to drive in this direction. And it has this period where it sits and it waits for the current to be, that to be the direction that the current is coming from. Because you basically want to drive into the current so that, because the rover, I think I told you the sediment is like. Sticky. There's a scientific, it's's sticky but it's also dusty i was thinking like that you know pig pen from peanuts you know like the dust cloud and so if you're driving and the current is coming from behind you you have this risk of like creating this dust cloud that then it's going to settle where you want to take a measurement. And so we don't want that to happen. So we want to drive into the current. So the dust

is pushing, is being pushed behind the vehicle. So we sit there and we have this period for like 12 hours where we're just watching the current meter and waiting for the current to be in a favorable direction. And if after 12 hours, it isn't, then we just go for it anyway. But we had current meter data going in that kind of helped us pick out a favorable direction that would be likely to work out. So anyway, so we basically know the direction it's going. We have an estimate of how far it's gone. And then we know where we deployed it. And of course, you know, when you deploy something at 4,000 meters, you know, we deployed it and of course you know when you deploy something at 4 000 meters you know there's a lot of currents between the surface and the seafloor so it can drift a fair bit um and then you just go with the ship and just range to it and get close uh

and then we release it acoustically so you just have to you don't have to be on top of it you just have to be close enough by to have a good acoustic link so you can release it. And then when it comes to the surface, it has GPS and radio, and it has iridium and Argo satellite beacons on it. So those things allow us to find it. When you say release, this is the explosive release of air so that it bounces to the surface? Well, I'd like to not think of it as too explosive. We basically burn a small wire, which is attached to this sort of linkage that releases a 250 pound weight. And when that 250 pound weight is released, the rover suddenly becomes positively buoyant and it just floats up to the surface.

And this is something that is done in many, they call them drop weights. It's like this weight that you drop to change the buoyancy of an instrument. So it's a very common tactic for recovering things from the seafloor. I thought there was another tactic that involved letting air out of canisters. I think, yeah. Well, there are things that have like um yeah i so for instance like i think one of our rovs has like these buoyancy they kind of have the ability to vary their buoyancy by letting air out of canisters um but the dropping a weight is you know i guess with something like the rover, like reliability is really important. And so, you know, dropping a weight is a pretty easy, pretty sure what's going to happen there, you know,

valves and stuff like that. Um, that gets a little more complicated. You said you hadn't been on an expedition to update the rover to to give it its annual physical um but you have been on other expeditions well i um have been on very few since for the past five five six years um i went on a great deal prior to having kids um and, and, uh, just last year I started going out again, going out to sea. Um, so, so I hoped, you know, actually, ironically, I hope that this would be the year that I would get to go see the Rover, but then because of COVID there was restrictions on how many people could go out on the ship. And also, it's a little trickier without child care to leave your kids home and go to sea. So this was not the year, but I have been able to start getting out to sea again.

What do you do? I mean, as an electrical engineer, project manager, you weren't controlling the ROVs. What are you doing on the expedition? Oh, that's a great question. Well, what I'm doing is that turning around of the instruments. So recovering the instrument, changing the batteries, fixing anything that's broken, downloading the data, putting everything back the way it should be. There's a lot of opening and closing of pressure housings, and there's usually things aren't exactly perfect.

And so trying to fix those things and then reprogramming everything to go do it again and then redeploying it but you know i'll do i mean i also i do also do a lot of things at sea that you know are not electrical engineering i'm happy i mean that's part of the joy of it is you know my favorite thing is we deploy these mooring lines, these, you know, these, and they have floats on them and there's a lot of shackles and, and you have to seize the shackles. You have to basically tie line, like a little thread around the shackle to keep it from opening up. And, and like, there's nothing I love more than sitting out on the deck and just tying these knots on shackles. My favorite job going to see. So you, there's not that many people

who go out. So you get to do some of everything, you know, which is fun. What do the shackles do so a shackle is just a way of connecting two things and so for instance okay so you deploy these instruments and okay a lot of times you have to have um flotation on these things that are okay so for the sediment trap is a good example. So, okay, let's say you want to put a sediment trap in the water. You're going to have to have a heavy weight at the bottom to hold it in place and also to have something to release. Okay. Then let's say you want your sediment trap. Well, I don't want it to be right on the bottom. I want it to be like 200 meters above the bottom. So you're going to have a line, a big rope between this heavy weight and your sediment trap. And then above your sediment

trap, you're going to have to have some floats because that's what's going to keep it standing upright. Does that make sense? Yes. Like if you can think, okay. So anyway, in order to keep all these things together, the ropes and the floats and the instrument and the line, you have these big metal shackles that allow you to connect rope or line, we call it line, line to instruments. And then the shackles, they have like pins that are just threaded and you just turn them to tighten them. But because there's a lot of motion in the ocean, no rhyme intended, seizing them is just basically a way of tying them so they don't become unthreaded. And it's just a little small mindless task, but it's my favorite thing to do. Well, and you're on a nice ship, and it's often beautiful, except for when it's freezing cold.

Yes, yeah. I love reading about the MBARI news articles. I picked up a couple of headlines. Glow your own. Comb jellies make their own glowing components instead of getting them from food. Or researchers discover carnivorous sponges that make their own light. Is it like living in a science fiction book? Some days. And I mean, some days it's like any other job. You know, when you're at sea,

it can be pretty magical. And there often are things that even someone who's spent as much time at sea as I have and done it for a long time, it's easy to just be like, oh, yeah, and there's another whatever, comb jelly. But there's almost always something that you see that like is pretty amazing. I don't know. I don't know if I use the term science fiction, but it's it's still. It's still manages to impress, you know, after many, many years, the diversity of all the things that live in the ocean and the cleverness of nature. Have you seen the green flesh? You know what? I did just recently in the past year. And not at sea, I might add. No, you don't have to see it at sea. It's just easier you know it's so funny i there are things like i have not seen like i

haven't seen a blue whale yet and i sort of felt like the green flash was kind of the same and then just this past year we were as i actually at work and we were taking a picture right around sunset of our group and then i looked out and i was like, God, I just thought I saw the green flash. And someone's like, yeah, I just saw it too. Yeah. I still haven't seen a blue whale, but I have seen the green flash. I've seen the Northern Lights. That's pretty cool. Do they sing? Well, I don't know, because you have to be up really late. You're kind of only half conscious, but they're pretty awesome. You've done work at both the Arctic and Antarctic.

Yes. Which one was better? Rate the polls. I'm thinking about this. It's a hard question. It is a hard question it is a hard question the Antarctic where we were which is the Weddell Sea so I never got to go on the continent

which would have been amazing but we were studying these drifting icebergs and it's just super dramatic and amazing the Arctic is a little more flat and but interesting in its own way because it's you know there are

like villages up there and you know it's not you know we uh once got dropped off from a ship in this like old whaling village you know that we had to be helicoptered away from. And it's so I don't know, they're both really amazing. I guess if I had to choose, I'd probably go Antarctic, but it would be a tough call. You know, what I like about both places is that you really feel like you're at the end of the earth. Like it's hard to I can't even really explain why. I don't know if it's the angle of the light or just the lack of anything. But you just feel it. You're like, here we are at the end of the earth. One more question.

You mentioned the Sargasso Sea. Yes. It's kind of an odd place. Could you describe it? Have you been there? I have. We did three expeditions crossing the Sargasso Sea. And we were going between Bermuda and the Bahamas, which was wonderful in and of itself.

And I think I chose that body of water. It's a very nutrient-poor body of water, which means there's not much life there. And it is subsequently the bluest water I've ever seen in my life. I mean, almost impossible, like movie magic blue. And the ship that I was on actually let us do swim calls and let us do snorkeling. And it was just, it was just crazy to be in water like that. So clear and just blindingly blue. So that is pretty special. Alana, it's been really good to talk to you. Do you have any thoughts you'd like to leave us with? No, but I really appreciate talking to you as well.

Our guest has been Alana Sherman, an electrical engineer and project manager at the Monterey Bay Aquarium Research Institute. Thanks, Alana. Oh, thank you. Thank you to Christopher for producing and co-hosting. Thank you to our Patreon supporters for Alana's mic. And thank you for listening. You can always contact us at showitembedded.fm or hit the contact link on embedded.fm. Now a quote to leave you with from Rachel Carson.

The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.