Podcast: How robots are revolutionizing chemical oceanography – Chemical & Engineering News

Robots in the ocean are giving scientists more details about processes above and below the surface that affect our weather, our food supply, and more. They’re also helping chemical oceanographers understand and record the effects that climate change is having on our waters. The past 2 decades have seen a growing fleet of uncrewed research vessels and a proliferation of chemical sensors, which together are giving chemical oceanographers access to an unprecedented wealth of data. That’s changing not just the way they think the oceans work but also how they themselves work. In this episode, ocean robotics pioneers and scientists making new sensors for the crewless vehicles tell tales of that work. And hacky sacks.

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The following is the script for the podcast. We have edited the interviews within for length and clarity.

Sam Lemonick: Oceans dominate our planet. They cover two-thirds of its surface. Imagine keeping tabs on all that area and the roughly 1,300 billion billion L of water those oceans contain. It’s a tall order for chemical oceanographers. The National Oceanic and Atmospheric Administration, or NOAA, estimates that the oceans are so vast that 80% of them remain unexplored.

What I’m trying to say is that there’s a lot scientists still don’t know about this massive—and massively important—system. But in the last few decades, their ability to study the ocean has rapidly expanded thanks to a fleet of robots and the sensors they can carry.

Studying the oceans is more than a matter of curiosity. This might not be obvious to landlubbers, but the oceans play a constant role in our lives, no matter how far we live from them. Ocean currents affect local climates. The Gulf Stream is part of the reason why England is warmer than parts of eastern Canada at the same latitude.

The oceans are part of the story of global climate change as well. They absorb heat from the atmosphere as well as carbon dioxide, one of the greenhouses gases warming the planet up. And the oceans remain a major food source. The fish and animals we eat are part of complex food webs which can be upset by changes in ocean chemistry.

Using robots to study chemical oceanography is still pretty new, but oceanographers have been at this for a couple decades now, and they’ve gotten pretty good at it. Thanks to robots, right this minute you could go online and find out what temperature the ocean is at almost any spot on the globe. Don’t believe me? There’s a robot about 4,000 km due west of Ecuador. Five days ago it reported the water was right around 28 °C at the surface. Balmy.

These robots’ capabilities are still growing, and they’re teaching us new things about how the oceans work and how they’re changing. Robots have already given us a clearer picture of how the ocean absorbs heat in a warming world and helped us find out that climate change is making saltier places in the ocean more salty.

I’m Sam Lemonick and you’re listening to Stereo Chemistry.

From a chemist’s perspective, the oceans are an aqueous solution. There are dissolved gases and salts, there are protons, there are metals. When ocean chemistry changes, it can change ocean currents, cause toxic plankton blooms, or wipe out key prey animals.

In this episode, we’re going to explore the advancing chemistry capabilities of a growing fleet of ocean research vessels that operate without crews. We’ll hear from researchers developing this expanding arsenal of analytical tools, measuring things like the pH, oxygen levels, and CO₂ concentration in the ocean like never before.

And we’ll hear how the robots are helping us learn more about our oceans and our planet. But before we get to the robots, let’s take a look at how oceanography was done before them.

Now, it’s not like oceanographers were waiting around for these robots so they could make measurements in the ocean. Scientists have been doing that for 150 years with the help of an age-old tool: the boat. And they still do. I’ll let Steven Emerson, an emeritus professor at the University of Washington, explain what it’s like to go to sea.

Steve Emerson: What you did is you got on a boat and you stayed on the ship for at least a month, maybe sometimes two months. And during that time you collect water. You either make measurements on that water right there in the lab on the ship if the ship has got a lab and if your equipment will work on a ship, or you brought the water back to your laboratory at the university or the NOAA lab or whatever and made measurements there.

Sam: Oceanographic research ships are big boats. The kind that Steve is talking about, that can spend a month or two at sea, are usually 100 m or so long and carry about 50 scientists and crew.

On boats that big, you can imagine that different scientists are often doing very different things. Like this one trip that Steve was on, where he worked in a refrigerated lab so samples they’d collected from the seafloor wouldn’t degrade while they analyzed them.

Steve Emerson: We’d be working on the equator. A lot of research was done on the equator. It was nice and warm outside and all the other scientists would be out playing hacky sack on the fantail. We would be freezing our buns off in this cold room.

Sam: I’m assuming the hacky sackers did their own science at some point too.

At any rate, it’s clear that chemists at sea face unique challenges. The one all ship-based scientists share in common is that their labs are in constant motion.

Seth Bushinsky: One of the first things you do when you get on a shift is tie everything down. And that’s not just put a strap over everything. It’s making sure everything can’t move in any direction. ’Cause everything that is not tied down will move eventually.

Sam: That’s Seth Bushinsky, a research scholar at Princeton University who will be a professor at the University of Hawaii, Manoa, next school year. And he assures me that, even with all that rocking and rolling, chemists can still do good science at sea.

Seth Bushinsky: In grad school, my group still did everything by eye, still did manual titrations. And even at sea, I think we are able to get as good of accuracy and precision as any of the automated systems can get on land. So it’s not like you sacrifice quality. It’s just you have to deal with everything moving.

Sam: It’s true. Scientists are still doing wet chemistry by hand on ships. But a lot of labs also use automated systems or flow systems so you don’t have to handle samples or reagents while the lab is rocking back and forth.

OK, now guess how many of the scientists I spoke with said seasickness was an issue? Would you guess none? Yeah, they said you just get used to the motion after a few days. I’ll have to take their word for it.

For oceanographers, the real limitations to ship-based observations aren’t hacky sackers or unsettled seas. Daniel Rudnick of the Scripps Institution of Oceanography at the University of California, San Diego, points to two big reasons why oceanographers started thinking about alternatives to these big research trips: they cost a lot and they only give you a narrow view of what’s happening in the oceans.

Dan Rudnick: If we wanted to measure something on the scale of an ocean basin, we’d have to get on a ship and make measurements as we went across, say, the Pacific, and that would take months. And after that, we’d have one line across the Pacific with a bunch of measurements along that line. And that would cost lots of money and lots of people and lots of time.

Sam: There are only a dozen or so oceanographic research ships capable of making a trip to the middle of an ocean, and they can cost tens of thousands of dollars a day to operate. They’re often restricted to certain preplanned routes. For instance the Northern Hemisphere has been sampled much more extensively than the Southern Hemisphere. And there are still places they can’t easily go, like the Arctic. Or places they can only go certain times of the year, like the ocean around Antarctica.

All of that makes alternatives to ship-based observations pretty appealing. But I want to be clear that oceanographic research vessels aren’t going anywhere. All the people I talked to who currently work with robots said some variation of the same thing: we still need ships.

Dan Rudnick: Ships are really important and they’re still a huge part of what we do, especially because there are measurements that can only be made from ships.

Sam: Ship-based observations are still the gold standard. Ongoing observations by ships reassure oceanographers that data collected robotically is still reliable. And, as Dan alluded to, ocean robots can still only measure a handful of variables, while ships have broader capabilities. More on that in a minute. First, let’s meet the robots.

Now, when I say robots, I’m not talking about C-3PO in scuba gear.

C-3PO: I’m going to regret this.

Sam: The first robots were called profiling floats.

These floats are metal tubes adorned with sensors and antennae. They’re about the size of an average person. And they help researchers create a profile of the ocean by sinking to different depths and taking measurements.

Ken Johnson is a senior scientist at the Monterey Bay Aquarium Research Institute who has led the charge when it comes to robotic biogeochemical oceanography. He gave me the rundown of what the standard depth profile looks like for one of these floats.

Ken Johnson: The float sits at a kilometer for 9 days, then goes down to 2 km and changes its buoyancy simply by inflating an oil-filled balloon and comes to the surface. And coming up through 2 km it makes chemical measurements: nitrate, pH, oxygen, chlorophyll, particles, temperature, salinity, and reaches the surface in about 6 h from 2 km and phones home to a satellite. And the data is processed in real time and goes right on the internet.

Sam: There are about 4,000 of these profiling floats in the oceans right now as part of something called the Argo program. And they’re spread almost evenly across the globe. The data they’re collecting helps oceanographers understand things like ocean currents, the global climate, and the ocean food web. More on that later. Let’s stick with the robots themselves before moving onto the gear they carry.

After profiling floats came gliders, which are essentially floats with wings, according to Dan Rudnick, who you met earlier. He says unlike the floats, gliders don’t have to stay in one spot.

Dan Rudnick: So the same time it goes up and down, it can fly horizontally on wings. And so where floats get taken wherever the current wants to take them, gliders we can control. So we use gliders when there’s a region that we want to observe especially well, like the coastal region off the coast of California where I’ve done most of my work.

Sam: Remember how Dan told us about some of the limitations of the big research ships? How sending a single ship to get data from a single line through the Pacific would cost a bunch of money and research hours? Gliders and floats help get around that. Dan was actually working with a small fleet of gliders when we talked.

Dan Rudnick: So I’m piloting right now. The most intensive experiment I’m doing now is in the Mediterranean where we have gliders in the water right now, south of Spain.

I used to spend typically a month a year at sea. And I did that probably for 20 years. And

I learned that there had to be a better way than having to be out on the ship all the time.

I love going to sea, but I love even more sitting here and right now we have about 15 gliders out in the water and they’re all sending their data back and I can watch it roll in.

Sam: Floats and gliders are the workhorses of the ocean robot world. But there are other vehicles out there autonomously patrolling the oceans.

There are wave gliders, which look like surfboards and use energy from waves to cruise the seas. There’s the jetyak. It’s a kayak with a water jet motor, hence jetyak. And then there are Saildrones, which are robot sailboats. And Saildrones stand out from the diverse fleet of aquatic robots.

Jessica Cross: I work with several different kinds, probably the most charismatic of which is the Saildrone, which is a brand new autonomous vehicle that’s about 20 ft long and 20 ft tall.

Sam: That’s Jessica Cross, an oceanographer with the Pacific Marine Environmental Laboratory, which is part of NOAA.

Jessica studies carbon dioxide in the Arctic, and she tells us part of the Saildrone’s unique character comes from its origin story. In 2009, a guy named Richard Jenkins set the speed record for a type of yacht that sails over land. It hit 202.9 km/h in a dry lake bed. The yacht didn’t look much like a sailboat. It was on wheels for one thing. And the sail wasn’t a piece of fabric. It was a rigid foil that looked like an airplane’s wing.

After setting the record, Jenkins started building prototypes for an autonomous sailboat with a similar design. He connected with NOAA scientists who helped him optimize the design to be useful for oceanographic research. And that’s how we got the Saildrone.

Jessica says what makes the Saildrone good for her work is that it’s fast, three to four times faster than other ocean robots. That’s important in the Arctic, where everything is big but the weather window is usually pretty small.

Jessica Cross: I tend to work in remote regions of the ocean very far away from land and very far away from infrastructure up in the Arctic. Alaska in particular has more coastline than the East Coast, the West Coast, the Gulf of Mexico, and the Great Lakes put together.

Sam: And because Saildrones don’t have crews, oceanographers don’t have to worry as much about the vessels hitting ice, which is a constant concern for research ships in the Arctic. Saildrones can stay out for a year, although Jessica says her lab usually only deploys them for a few months at a time.

They are limited to making observations only at the surface and in the top couple meters of ocean, but Jessica says that’s still giving oceanographers a much broader picture of what’s happening with carbon dioxide in the Arctic, as a complement to ship-based observations.

Jessica Cross: Ocean robots are sort of expanding our portfolio. I wouldn’t say that we are losing ship-based missions at all. They still represent a really important traditional tool that we use to collect essential data. The Saildrone doesn’t get into the bottom waters. We have to have that data.

Sam: What the Saildrones provide is a different type of data. And now it’s time to dive into that data. We’ve talked a little bit about what researchers want to measure, but how exactly are they measuring it? The answer, as you might imagine, involves some chemistry, and we’ve got all of it heading your way after this break.

Matt: Hey there. This is Matt Davenport, and I’m producing this episode of Stereo Chemistry as we speak. Well, I mean, I’m speaking. You’re listening.

And I really hope that you love what you’re listening to. So does everyone involved with Stereo Chemistry. That’s why we wanted to take this opportunity to ask for your feedback. What do you like? What can we do better?

There are a bunch of ways you can let us know, but it would be amazing if you could leave us a review and a rating on iTunes. If you don’t want to be so public about it, shoot me an email at m as in molybdenum underscore davenport at acs.org. That’s m_davenport@acs.org.

But please consider sharing a review and rating on iTunes. It’ll help other people find our podcast and, more importantly, it will help all of us here at C&EN make this show better for you and all of our future listeners. Thank you so much. Now back to the ocean robots.

Sam: Before we get into the chemical measurements our ocean robots are making, let me introduce a little terminology. Chemical oceanographers distinguish between sensors and analyzers, and we’re going to be talking about both.

In simple terms, analyzers do some kind of chemistry on a sample to make measurements. Sensors make measurements in other ways, like detecting a current. Sensors are more common on long-duration robots like profiling floats, which can operate for a decade, because they don’t rely on chemical reagents that can degrade or run out, like analyzers do.

Now that that’s squared away, let’s talk measurements. Steve Emerson is a good person to start with. He’s the one who was stuck in a refrigerated lab while his friends played hacky sack in the sun.

Steve studies carbon, and the oceans play a big role in the Earth’s carbon cycle. They absorb carbon dioxide from the atmosphere. Photosynthesizing plankton take up carbon dioxide from seawater. When they—or the animals that eat them—die, they take that carbon with them to the seafloor, making the ocean an important sink for CO₂.

Steve researches how organic matter—carbon—moves from near the surface down to the deep ocean. And figuring out how to do that on a float took a bit of work.

Steve Emerson: One way to study it and the way that I decided to do this is by studying the oxygen mass balance in the surface ocean. ’Cause during photosynthesis, if you create a mole of organic carbon, you create about a mole and a half of oxygen.

You can kind of imagine this, for every mole of carbon that leaves the surface of the ocean by either falling down or by mixing to the interior is balanced by about a mole and a half of oxygen that goes from the surface of the ocean into the atmosphere.

Sam: So you can calculate how much carbon goes down if you measure how much oxygen goes up. And Steve says you can measure how much oxygen goes up by measuring the difference, or the gradient, between the partial pressure of oxygen in the atmosphere and the partial pressure of oxygen in the water near the surface. Partial pressure is a way to measure the proportion of one gas in a mixture or solution.

Steve Emerson: But that gradient is really tiny. The oxygen concentration in the surface ocean is, say, 200 μM, and the gradient might be 1 or 2 μM, which means that in order to calculate the flux of oxygen to the atmosphere, you have to have very precise measurements of oxygen in the ocean.

Sam: US oceanographic research ships have been measuring oxygen concentrations every month at two sites, one in Hawaii and one in Bermuda, since the late 1980s. And I feel like you deserve to know those projects are called HOT and BATS. Anyway, as Steve was saying.

Steve Emerson: These time series sites have been really important, but it’s restricted. Even a country like the United States can only afford to do that two places in the ocean. So you really are not learning much about every other place.

Sam: Remember, research ships can cost tens of thousands of dollars a day to operate. The limits of that data are why Steve wanted to put oxygen sensors on profiling floats. He could buy oxygen sensors and put them on the floats to make measurements. But the problem was, the sensors’ measurements would drift over time. So when you first put them in the water you would get really accurate measurements, but after months and years of going up and down, you couldn’t trust the data they were reporting.

The solution came from Arne Körtzinger, an oceanographer at the Helmholtz Centre for Oceanography in Kiel. In a 2005 Journal of Atmospheric and Oceanic Technology paper, he demonstrated that the sensors’ oxygen measurements were drifting. And then he wrote, “Since the sensor responds to the oxygen partial pressure, it is also capable of measuring in air. Therefore, oxygen measurements taken in air while the float is at the surface can potentially be used for drift control.” Steve can explain.

Steve Emerson: We know that the oxygen concentration in the atmosphere is everywhere the same to about four decimal places. So when the float comes up and ends its profile and sticks its antenna out into the atmosphere to send the data home, you could just keep measuring oxygen. Actually, every time the float surfaces, you calibrate it.

Sam: So how do you add an oxygen sensor to an Argo float? Remember Ken Johnson, the guy who championed using floats for biogeochemical research? He’s got a great analogy.

Ken Johnson: The vision I always have of a float is the old TV series The Beverly Hillbillies, when they were coming to town on the pickup truck with granny and her rocking chair strapped on the roof. That’s kind of the way the floats are now. They were designed for something else and we’ve got stuff strapped all over them.

Sam: The biogeochemical Argo program has about 300 floats in the ocean right now. They carry sensors for oxygen, pH, nitrate, chlorophyll A, and more. But there are other sensors in the pipeline. Some of which are being developed by Matt Mowlem, the head of ocean technology and engineering at the National Oceanography Centre. He leads a team of about 50 engineers.

Matt says his research has taken him in the direction of reagent-based chemical and biological analyzers. When he started looking around the field at the analyzers that were out there, he wasn’t impressed.

Matt Mowlem: They were beset by reliability problems. They weren’t very rugged. They really needed expert users to operate them.

A lot of them used very large quantities of reagent as well and created a lot of waste, which would be problematic to contain or would have to be put into the environment, which we didn’t think was a very good idea.

Sam: But Matt really liked that reagent-based systems, which pump chemicals through fluidic channels, could make very accurate measurements. That makes sense. These analyzers are based on the same wet chemistry approach that oceanographers use for ship-based measurements. Matt just needed them to be better. So his team dove into microfluidics.

Matt Mowlem: So reducing the size of the fluidic channels down to the order of a few tens or hundreds of microns and the whole thing becomes a lot smaller. You use less power, less reagent, you consume less energy, generate less waste.

Sam: Matt says there was a lot of skepticism about using microfluidics in the ocean. Seawater is full of stuff. And, as any boat owner knows, some of that stuff is alive and likes to attach to things. And then start growing. Matt says people assumed the tiny channels in a microfluidic device would quickly get clogged.

Matt Mowlem: I think I was probably of that view at the beginning. I thought, well, let’s just do a few weeks’ trial and see where we get to. And if it survives, then maybe there’s something in this.

Sam: It turned out that the group didn’t see any problems in their prototypes, even in murky, very biologically active water near a dock in southern England. Matt suspects it’s a combination of the chemicals they use, the fact that there’s no light inside to help things grow, and the tiny amounts of seawater that actually flow through.

These days, the group’s devices work using two kinds of chemistry.

Matt Mowlem: One which is based on colorimetry. So detecting absorbance of a colored product and those devices have a store of the reagent that reacts with seawater to produce the color.

And the other way of doing it is with luminescence or fluorescence. So there is the same idea that the seawater gets mixed with the reagent and then you get a luminescence product or a fluorescence product.

Sam: For instance, their iron analyzer mixes seawater with ferrozine, a chelator that binds iron(II). The resulting complex has a red-purple color with a maximum absorbance at 562 nm that’s detected by a photodiode.

One of the limitations of microfluidics is how much reagent they can carry and how much waste they can store. Matt subscribes to the pack-it-in, pack-it-out philosophy. Microfluidic devices wouldn’t last for the entire 5- or 10-year deployment of, say, an Argo float.

The reagents can also degrade over time, which his group has been addressing. In cold water, like the Arctic, he says reagents for doing nitrate and nitrite measurements are stable for as long as a year.

Matt Mowlem: Typically, you’ll get 3 to 6 months in warmer areas. We are doing some things about reagent lifetime. You can get longer lifetime—there’s some techniques which are in development now, I can’t really talk too much about; we’ll try and stretch that out. But other chemistries are a bit more robust. So the dyes for measuring pH, total alkalinity, they’re much more robust, will last for a long time.

Matt Mowlem’s son: Daddy . . .

Matt Mowlem: I’ve got another interruption. Hello.

Sam: Yeah, that was Matt’s son.

Matt Mowlem: Right. Come on in. Quick.

Sam: What Matt was going to say was that those dyes for measuring pH and total alkalinity can last as long as 3 or 4 years based on their tests.

In the meantime, however, while Matt and others are inventing and refining new kinds of sensors and analyzers, there are still important variables that ocean robots can’t measure directly.

One of those is carbon dioxide, which is kind of crazy to realize when you think about how much attention CO₂ gets these days. CO₂ is a greenhouse gas that’s contributing to global climate change, and humans have dumped billions and billions of tons of it into the atmosphere by burning fossil fuels.

Oceanographers and climate scientists know that the Earth’s oceans are absorbing a significant fraction of the carbon dioxide humans put into the atmosphere, enough to blunt the effects of global warming. But they also know that as temperatures and CO₂ concentrations rise, the ocean’s ability to take up carbon dioxide may change. Understanding that, and the effect that CO₂ has on sea life, are big questions oceanographers are hoping ocean robots will help them answer.

Here’s Jessica Cross again. She’s the NOAA researcher who talked to us about those charismatic sail drones. I should also remind you, she’s studying CO₂ in the Arctic. Improvements to sensors have already had a huge impact on her work.

Jessica Cross: Sensor development has been able to reduce the uncertainty in CO₂ flux measurements, that movement of CO₂ between the atmosphere and the ocean, by 50%. We understand it twice as well as we did 15 years ago.

Sam: Oceanographers can measure CO₂ directly on ships and with bigger robots like Saildrones, but they don’t have reliable sensors they can deploy on floats, which are more ubiquitous. So researchers have adapted. They’re taking advantage of the carbonate system to make measurements of CO₂ with floats.

Let me explain. When CO₂ dissolves in seawater it reacts with H₂O to form carbonic acid. Carbonic acid is in equilibrium with bicarbonate and carbonate ions in water. By measuring aspects of this system, scientists can figure out how much CO₂ is present.

Here’s Jessica’s colleague, Nancy Williams, a postdoc at NOAA in Seattle. She’s studying CO₂ levels in the ocean around Antarctica.

Nancy Williams: What we need is more than one measurement of the carbonate system to really constrain the chemistry that’s going on. So there are four measurable parameters. There’s pH, alkalinity, dissolved CO₂, and the partial pressure of carbon dioxide. And so if you really want to constrain the system, you need to measure two of those four. And the floats are only measuring pH.

Sam: So that’s one parameter. Another one, alkalinity, can be estimated based on salinity measurements, which Argo floats also have sensors for. From there, oceanographers are able to estimate the partial pressure of CO₂ in seawater. And Nancy says we’re learning that the oceans might not work exactly how we thought.

Nancy Williams: It seems like the floats are observing much more outgassing of CO₂ in the wintertime then we had previously thought. That has implications for the overall global carbon budget because if the southern ocean is releasing more CO₂ than we thought, then that means that CO₂ has got to be going somewhere else. So is it going into the ocean somewhere else? Is it going into the land? You know, where did we go wrong in our carbon budget? And so it’s, it’s pretty exciting and I think it raises more questions than it answers. It’s just sort of a peek into what we could learn from these kinds of platforms as they expand to other ocean regions.

Sam: Nancy says ocean robots aren’t just helping oceanographers better understand the oceans. They’re also changing the way that chemical oceanographers work.

Nancy Williams: Since I started grad school, since I started my PhD, I really haven’t gone to sea that much, which is sort of sad because it’s fun to go to sea. But it’s also really exciting because I can sit at my computer, either at work or at home or wherever I am and download this data and work on it. And it’s available to the public. It’s quality controlled in near real time.

And I think it’s going to make oceanography more accessible to groups that maybe don’t have as much funding to go out and do fieldwork, people in other countries whose governments don’t have as much funding for that kind of work.

Sam: One person who’s thought a lot about ocean robots and how they could enable more researchers to participate in monitoring our waters is Eric D’Asaro, an oceanographer at the University of Washington. He was among the first oceanographers to build and use floats. He’s a pioneer in this field, using the floats to measure physical properties of ocean water.

Eric D’Asaro: During the ’90s I was actually fairly sick with chronic fatigue, and I had been an observational oceanographer. And my fun thing to do was to go off to interesting places like the Arctic, and if it was crazier and more adventuresome, the better it was. Well, if you’re sick that’s not a really good idea. And so I said, well, what can I do observationally that lets me be an observational oceanographer while I could still, like, take a nap anytime I need to.

Sam: That led him to start building and deploying drones and gliders, something he’s been doing ever since. And now those robots’ grandchildren and great-grandchildren are unleashing a fire hose of data on oceanographers. Jessica Cross again.

Jessica Cross: You’re collecting more and more data than you ever have before. Programming is an essential skill. Big data analysis is an essential skill. Certainly different from the 300 data points data sets that I worked with when I was first starting in oceanography.

Sam: All of this—the robots, the sensors, the data and the tools to handle it—means that chemical oceanographers are sampling and understanding the Earth’s oceans in ways they never could before. And that, says Dan Rudnick, is a big responsibility.

Dan Rudnick: Basically, our goal is to be on the job. There are changes that are happening in the ocean. There are natural changes, there are changes caused by people, and they’re on all kinds of different timescales and length scales. Basically, our job is to make sure we have the data, because now never happens again. Right? Today never happens again. We have to be on the job every day. And our goal is to create a record that everybody can use.

And so that’s what I like to leave people with when they wonder, you know, why we worked so hard at this? It’s really so in decades we have the data we need to make good decisions.

Sam: We’ll be back next month when Kerri Jansen will look at a scorching-hot area of forensic science. So subscribe to Stereo Chemistry and make sure you don’t miss it. This episode was written by me, Sam Lemonick, and produced by Matt Davenport.

The music you’re hearing now is “Morning Cruise” by Jens Kiilstofte, who also wrote “Dance of the Pixies” and “September Sky.” You heard those earlier in the episode along with “Where Was I?” by Lee Rosevere. The track that opened this episode was “Blind Love Dub” by Jeris. We’ve got links to all of those, along with this episode’s script, on our website at cen.acs.org.

Thanks for listening.

“Blind Love Dub” by Jeris is licensed under CC BY 3.0.

“Morning Cruise,” “September Sky,” and “Dance of the Pixies” by Jens Kiilstofte are licensed under CC BY 4.0.

“Where Was I?” by Lee Rosevere is licensed under CC BY 4.0.