Science’s Breakthrough of the Year, and psychedelic drugs, climate, and fusion technology updates
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This is a science podcast for December 13th, 2024. I'm Sarah Crespi. First up this week, news editor Greg Miller joins producer Megan Cantwell to discuss science's 2024 breakthrough of the year. They also talk about some of the other scientific achievements that turned heads this year, from ancient DNA to precision pesticides and the discovery of a new organelle.

Next on the show, I'm joined by news staffers to catch up on stories they've been following through the year. First, a bumpy regulatory road for certain medicines with editor Kelly Cervic. Then we hear from staff writer Paul Vussen about why scientists think 2023 and probably 2024 will be the hottest on record. Finally, staff writer Daniel Cleary on what happened this year with Fusion Power.

Somehow we are almost at the end of the year again, which means it's time for a long held tradition here at Science, announcing our breakthrough of the year. Science's editors and reporters select what they believe to be the most significant advance for the year alongside nine runners up in a variety of disciplines. I'm here with Greg Miller, who edited the section this year, and we're

And we're going to talk through some of the highlights. Thank you so much for joining me, Greg. Hey, glad to be here. We're going to start with an advance that was enabled by our 2022 Breakthrough of the Year, JWST. One of its main objectives is to look back into the early history of our universe. Could you talk a little about what its main objectives were from its onset?

Yeah, so it's basically designed to look at the dawn of the universe back less than a billion years after the Big Bang, so something like 13 billion years ago. And scientists would love to know more about the first galaxies and other objects that formed in that era.

But because the universe is expanding, the light from those objects, in addition to being incredibly far away and faint, is shifted into the infrared. And so previous instruments like Hubble weren't really equipped to see them. But that's exactly what JWST is designed to do. And this year we started to see some of the fruits of that. Yeah, it's definitely doing a good job performing as expected, probably most researchers would say, right? And it spotted a bunch of these objects

that are pretty bright and pretty old.

Was this a surprise to researchers? Were they expecting to see this? No, not so much. Right off the bat, JWST started seeing these surprisingly bright galaxies, some of them as big as our Milky Way. And according to the current thinking on galaxy evolution, they shouldn't be there. They shouldn't have had time to evolve so early in the history of the universe. So that's been kind of a surprise and a puzzle that came really early.

after JWST started working. Did they have theories as to why we might be seeing more of these galaxies than previously thought? Oh, of course they've got theories. They always have theories.

What was exciting this year was they started to get some data to start refining and confining those theories. So one idea is that stars in this early era of the universe grew more rapidly and efficiently than thought. And so if the galaxies have large numbers of huge stars, that could lead to unusually luminous galaxies.

The spectroscopic data that break the light into its component wavelengths found the presence of large clouds of gas and dust in the early galaxies that contains carbon and oxygen, which are chemical elements that can only form in earlier stars that died and blew up as supernova. The idea is that there was an even earlier generation of stars that

died and blew up and that created conditions that were rife for the efficient rapid growth of big stars in the early universe. Now a discovery that happened on our own planet, a new organelle was discovered this year in marine algae. What exactly does this organelle that they call the nitroplast do?

It fixes nitrogen aptly enough, which is to say it converts nitrogen gas into other forms like ammonia that organisms can use more efficiently. Fixing nitrogen, is this very unique? Has it been seen in other organisms? What makes it so unique that they found it in these marine algae?

Yeah, so it's been well established in bacteria and cyanobacteria, but those are prokaryotes. So those are organisms that don't pack their DNA into a nucleus like we do. We and the marine algae are eukaryotes, which...

means we have these organelles like the nucleus where the DNA is and mitochondria that make energy. It's sort of a compartmentalization of the cell. So this is the first time that these, you know, a nitrogen fixing eukaryote has been shown. When this discovery was announced, I'm sure it got a lot of people's, a lot of gears turning in people's mind, one thought.

Can we incorporate this into plants so we don't have to apply fertilizer anymore? They can do it themselves. Is this possible? Yeah, it probably weighs off, but it is a neat idea because if we could cut down on the amount of nitrogen fertilizer that's applied to crops, that could potentially avert all kinds of ecological, environmental side effects. The idea, yeah, would be to put nitroglass in crop plants

It's a little tricky because the host plants also have a role in this partnership. They need to provide certain things for the nitroblast to be able to function. So the hope is that maybe some of this work with diatoms that are catching this evolution at an earlier stage could maybe point to some of the steps that are necessary. Yeah.

That one maybe we'll see decades down the road. This next one is about a new understanding of how plate tectonics work and how they shape continents. So what did researchers previously think happened exactly in a rifting zone when plate tectonics were shifting away from each other? Yeah, so the thought was that when the plates are moving away from each other, hot

rock from the mantle rises up and it can see volcanoes along the rift zone. It's a slow moving process because it's geology, but it's also still pretty violent. But localized to the rift zone was the thinking. What kind of clued researchers into thinking that there's something missing here? They actually are impacting far beyond just

kind of as a localized event. Yeah, this is an interesting twist to the whole plate tectonic story. It started with some modeling studies that looked at how the mantle rock rises and falls as it cools, kind of like a lava lamp effect. And the researchers saw in their model that the mantle rock wasn't just churning in place, it was actually spreading out laterally from the rift zone and kind of crawling along the underbelly of the continental plates.

There are, in different parts of the world, in Brazil and South Africa, these high plateaus on the interior of continents that are kind of puzzling to geologists because they don't have a good explanation of how they got there. They looked at dozens of these sites looking at already published data on the rocks. They pieced together when the uplift occurred.

happened in those areas and saw that it coincided remarkably well with when their models predicted the mantle waves would be passing through that area. And when we say slow moving, how long is it taking to get towards kind of more of the middle of a continental plate from these rifting zones? Yes, it's super slow. If I remember, it's something like 15 to 20 kilometers every million years. Oh my God, yeah. That takes some time. Yeah, not even, it makes a snail look supersonic.

I think my favorite twist to this story, though, is that mantle waves might also have something to do with diamonds and where exactly they're appearing on our Earth. Yeah, this is really interesting. So diamonds are forged under extreme temperature and pressure deep in the mantle, and they come to the surface on these tubes or pipes of magma called kimberlites. It's kind of a puzzle of how they get to the interior continents where we find them.

And so there was a study that looked at the coincidence in timing of when these kimberlites formed or when they erupted rather, and when the mantle waves were passing through. And they saw that it looks like, again, the timing works. Like it's as if the waves are kind of passing through, like popping all the corks on the kimberlite tubes and causing these eruptions where diamonds are found.

Does this mean that they may know where some diamonds are now that aren't known about? Yeah, I think that that's definitely an area of interest using this knowledge now to predict where they might be. Switching gears to our ancient ancestors, every year I feel like we're learning more and more about them. And at the end of last year, researchers published A New Way to Understand Family Relationships and Descendants of Ancient People Using DNA.

What are scientists looking for within the genetics of ancient DNA to see whether or not people were related to each other? Yeah, so it's really similar in principle to what ancestry companies like 23andMe do to find your long-lost third cousin or whatever. So basically looking at the frequency and length of

of identical stretches of DNA in different people. In this case, people may be buried in a cemetery that's very, very old. So people obviously with more of these identical chunks of DNA are more closely related than people with fewer chunks. How refined is that level of relationship that we can see? Can we see whether someone's a brother and sister versus a mother-father?

No, that's a good point. That's one limitation of it. So it can tell you the number of degrees of biological separation. So for instance, like a second degree relationship could be a grandmother and a grandson. It could be an aunt and a niece, or it could be first cousin. It tells you how related people are, but it doesn't tell you exactly what the relationship is. So researchers did use this new technique this year in a few different studies. What are some

some examples of how it can sort of supplement what traditional archaeology tells us. It seems like the power is really in combining the genetics with the traditional archaeology to gain more than you could from either one alone. But what the genetics is really adding is things about the social structures in these ancient societies. In one study, for example, of Celtic chieftains in southern Germany,

in a cemetery that's about 2,500 years old, they did this kind of analysis and found that power seemed to pass through the maternal line, which is interesting. At the same time, another study that came out this year looked at Stone Age farmers and found that the male line was the key in that society. So these are the kinds of things that we're getting a glimpse of that previously weren't really possible.

Well, we're going to go on to this year's breakthrough of the year, which is lenacapavir. It's an injectable drug that could mark a huge turning point in the HIV AIDS epidemic. What did clinical trials that published this year show about how well this new preventative drug actually works?

So lenacapivir is given as an injection every six months as a preventive, as what's called PrEP, pre-exposure prophylaxis. So it's not a vaccine, but it works to keep people from getting infected when it's given every six months. These trials were actually astoundingly successful. There were two big ones, one in Africa, where

that looked at adolescent girls and young women and found 100% efficacy, like not one single infection in 5,000 people, which is pretty unheard of in clinical trials. And then a second

trial came out a few months later with a more diverse population of people who have sex with men. And that one was based in South America, Asia, Africa, and the US. And there, there were two infections in 2000 people, which again is just an astounding success rate for a clinical trial.

specifically in this first trial that they did in young women in Africa. Previous forms of PrEP, which have been mostly daily oral pills, there is a two-month injection that hasn't quite got on, just haven't been activated

as successful. What made the difference here as to why this six-month injectable worked so well compared to previous trials? Right. So the daily pills work great if people take them, but that's an obstacle because people have to get the pills. They have to take them every day. There can be stigma attached to taking the pills. There can be relationship dynamics that get in the way. So for a variety of reasons, the oral pills aren't

as good as an injection that you can just get twice a year and

be good to go. An interesting part of this story for me is one, that it took a really long time for this drug to be developed and that it also wasn't initially conceived of even as this form of a preventative treatment. It was actually conceived of as a drug for people where the current HIV drugs on the market just aren't working for them. Could you kind of talk a little bit about that story, why they were seeking this sort of different approach to an HIV antiretroviral?

Yeah, this drug has a really different mechanism. It attaches to the capsid proteins. The capsid is the sheath or cone that surrounds the genetic material of HIV. The road to lenacapavir was paved almost 20 years ago with some research that changed the way

scientists think about how the capsid works. So initially, they thought that once the virus enters a cell, the capsid kind of disintegrates, the RNA goes freely out into the cell and wiggles its way into the nucleus where it co-ops the host's DNA to make copies of itself and so on. But that turns out to be not exactly what happens. The cone itself goes into the nucleus of the host cell through pores in the nucleus.

And so what lenacapivir does is it binds to the proteins in the capsid and makes the cone rigid so it can no longer squeeze its way through the nuclear port and infect cells. So that novel mechanism appears to be part of the key to the drug's success. It's a new technique that can be effective for both preventing people from getting HIV and also treating people with drug-resistant HIV, which means

It seems like something that would be great to be rolled out on a wide scale here. What's Gilead's plan for making it more widely available? Yeah, that's the key to whether this makes a difference really is getting it to people who are at risk of infection. So Gilead so far has reached agreements with a handful of generic drug makers to make low cost versions of the drug and supply them to over 100 low income countries.

But so far, they have not made an agreement with middle-income countries, which includes countries like Brazil that has the highest HIV infection rates in South America. There are quite a few obstacles, though. In addition to affordability, it has to get to the clinics. There has to be kind of the health system infrastructure in place for delivering it. Transportation can be an issue in some parts of the world.

A lot of things have to come together if Linacapabir is going to fulfill its promise to help accelerate the end to the long, long HIV AIDS epidemic that we've been living through. Thank you so much, Greg, for going over all of this. Yeah, thank you. Greg Miller is a contributing editor at Science. You can find links to all the content we talked about and more at science.org slash podcasts. Stay tuned for a catch up with the news team on stories that developed all year long.

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As part of our end-of-the-year extravaganza, we're going to bring on a few news reporters and news editors to talk about some of the areas that seem to move really quickly in 2024. We just want to catch up here at the end of the year. We have Kelly Cervic, who edits neuroscience and biology stories. We have staff writer Daniel Cleary, who writes about space and physics. But this week, we're mostly going to be talking about fusion technology.

And we have staff writer Paul Vussen, who covers a lot of things from earth to sky. We're going to focus on climate when he comes on. All right, so let's get started. Okay, Callie, are you ready? I had you on the show to talk about psychedelics in 2021. I literally thought it was last year. We discussed this novel approach of using ecstasy and talk therapy together for treating PTSD. And it was in late stage clinical trials when we talked.

Kind of the unusual factor there was that it would need to be prescribed together. Can we talk a little bit about kind of the ups and downs of psychedelics in the news this year? Yeah, obviously there's been a lot of enthusiasm among some researchers and also just in the general public about using psychedelic drugs, among them MDMA, which you mentioned, to treat psychiatric conditions. Anxiety, PTSD.

Depression. And that has been really hard to treat with medicine for a long time. I think going into 2024, there was this expectation that the front runner and potentially the first treatment that was going to go mainstream and win formal approval in the US

was going to be this one from Lycos Therapeutics, which was the one that we came and talked about in 2021 when it was in late stage trials. And that approach is combining MDMA with psychotherapy to treat post-traumatic stress disorder. Yeah. And it was very interesting when we talked about it, that it's not just

Any old psychiatrist or any old psychologist doing this treatment is specifically tailored to working with the drug. Yes, it was a kind of unusual model. And like you say, it was this manualized therapy that kind of was developed by this company and had its own kind of flavor, which unfortunately I think was a little bit hard to define and ended up being a challenge for them. What happened this year with the Ecstasy Plus Talk therapy? Kai Kupferschmidt has been following this really closely for science and watching as

First, an advisory committee and then the Food and Drug Administration itself came to their decisions about the application. And the decision was a thumbs down. Regulators decided that Lycos had not convincingly shown that the benefits of this drug were going to outweigh the risk. There's a whole pile of reasons for that failure. And Kai highlighted a few of those in his coverage that I think maybe it's worth talking about briefly here, too.

There have always in psychedelic trials been concerns about how to blind the participants and keep them from knowing that they're on a psychedelic drug versus a placebo. That definitely reared its head again in this case. And then there were issues with Lycos itself. The company failed to collect some data in its trials that the FDA advisors wanted to see, such as reports about euphoria from the treatment that could indicate the potential for abuse.

There were accusations that trial participants had been pressured not to report negative outcomes, like worsening mental health symptoms after getting the treatment.

And Lycos has also acknowledged that a participant in one of its earlier trials was sexually abused by her therapists. And that amplified longstanding concerns about how to keep patients safe when they're in a vulnerable situation and they're taking these mind-altering substances. And that continues to be a conversation. And finally, there's the fact that

Like you say, Lycos wasn't just seeking approval for a drug. It was combining a drug with psychotherapy. And FDA doesn't regulate talk therapy. And so...

There's some speculation that this combination just made it really hard for regulators to deal with and approve. So where does that leave the field? I mean, I feel like this was kind of the forerunner, the poster child for psychedelics. Are people questioning everything? Are there other frontrunners that could catch up now? There are definitely lots of other research teams and other companies that are moving ahead.

And Lycos itself is moving ahead. They said in October that they were continuing to work with FDA. They have plans to potentially do another phase three trial to try and reassure regulators. And then meanwhile, there are other companies, Compass Pathways and the nonprofit USONA Institute, both have phase three trials that are ongoing for treating depression with psilocybin, the compound found in magic mushrooms.

And many more are in earlier stages of development. So I think, yes, this year was a year of tremendous disappointment for people who believe in this field and want to see drugs approved. But it was absolutely not the end of the road. OK, Kelly, that's super fascinating. We're definitely going to have to check in again with Kai or with you next year to see what's going on with that.

So we're going to talk about the second thread I wanted to follow, which sounds pretty different, but it does involve the brain. This is antibody drugs, dosing people with antibodies to target disease in the body. And in this case, it's for Alzheimer's. Again, the regulatory road has been bumpy. Can you catch us up on this? Sure. Yeah. The approval in the U.S. of these two new drugs for Alzheimer's disease is

has been a huge development this year. One of them, licanumab, was actually approved in 2023, and the second one, dinanumab, was approved this summer. But 2024 has really been the year that clinicians have started to have to contend on a large scale with what these drugs mean for treatment, and they've had to start making decisions about how to interpret and apply the evidence from clinical trials to the real world, and

And that's something that my colleague Jennifer Cousin-Frankel has been tackling in some of her recent reporting. Well, so what are some of the questions that physicians would have if they were going to be considering dispensing these drugs? So the tricky thing about these drugs is both of them take aim at beta amyloid, which is this protein that forms sticky plaques in the brain that are implicated in Alzheimer's. They're the first to clearly show amyloid.

a slowing of cognitive decline. And what people really want is slowing or reversing of cognitive decline. That's what you want from your Alzheimer's drugs, right? Sure. But it's important to say that for both of these drugs, the benefits are considered modest. They don't reverse the disease. They don't stop the progression. And so for doctors, you combine that with

some very clear and sometimes concerning side effects that we know about from this class of drugs, namely swelling and bleeding in the brain that are collectively known as ARIA, amyloid-related imaging abnormalities. And as Charles Piller has reported in Science, licanumab was linked to multiple deaths and brain injuries among clinical trial participants getting the drug.

So it's something that doctors have to be really careful about when they're deciding whether to prescribe. Was it a surprise that these were approved for use? They were certainly controversial approval decisions. I think compared to the very first anti-amyloid drug that got FDA approval, aducanumab, these had a much clearer signal of benefit from clinical trials.

But like I said, it's been known for many years that these risks are there. And so both of the approvals came with warnings. And if you look around the world at the decisions that other regulators have made, it's been kind of all over the place. Lacanumab got approved in the US, in Israel, in a handful of countries in Asia. It got rejected in Australia. It got kind of approved in the UK, but the UK National Health Service might not pay for Lacanumab or Denenumab.

So if you're a doctor looking at all this in the U.S. where you have the option to prescribe, it's not at all straightforward what to do. What have we seen so far? You know, I know Jennifer reported on some of this. Is there a consensus or are the doctors doing a bunch of different things?

There's a range of decisions being made. There's just a tremendous need and desire among patients and their families for something that might slow this very devastating disease. But some doctors are deciding to prescribe more widely. Some are prescribing in a very limited way. And Jennifer has spoken to people who are saying, I'm not going to prescribe this at all. That's my policy right now.

So that's another one we're going to definitely have to keep an eye on. And I think more of those drugs will be coming down the pipeline in the next few years as well, right? Yeah, there are certainly others in development to watch. All right. So Kelly, before I let you go, it is our end of the year wrap up show. So I wanted to ask you to kind of look back at your year. And was there any story that was particularly interesting?

meaningful or memorable to you? Anything that stuck out that you wanted to mention? Yeah. One story that has stuck with me and that I have thought about a couple times since has been this article that Meredith Wadman wrote about the researchers and healthcare workers in Haiti who are determined to keep studies running

Despite escalating chaos and violence in that country, she talked about these motorcycle drivers who were doing these overnight shifts to dispatch care to sick children and infectious disease surveillance teams that were severely limited in how they could move around the country, but they were by no means giving up on the work.

So since that story, gangs in Haiti have only expanded their territory. And we learned recently about kind of a new wave of violence in that country. So I think her story is still a very present reminder of the

heroic efforts that go into doing science and medicine in these extreme situations. And I think that's why it has stayed with me. Yeah. We actually had a researcher involved in that project on the show earlier, Eric Nelson. He and I spent a nice time talking about cholera and how it has this almost ecological balance with phage inside the gut. But at the same time, all this data came at huge cost to all these researchers on the ground in Haiti. Absolutely. And yeah, I remember one of the sentiments in Meredith's story was

People who are outside the country who are doing research kind of feeling like we owe it to our colleagues who are putting themselves through all of these dangerous situations. Like we owe it to them to continue the work the best we can here. That was Kelly Servik. She's a deputy news editor here at Science. Next, we have staff writer Paul Vussen. He has a huge beat. We're going to focus on climate.

You cover so much for the new site. Earth, sky, space, everything in between. But I think for this end of year wrap up segment, we should talk about climate change.

climate and a story that you followed all this year, which is about last year. The record temps in the prior year in 2023 brought out a lot of theories on why we saw such record high temperatures, even with climate change driving, you know, driven by greenhouse gases. This is still out of range of what the predictions were for 2023. In some ways, it's also a story about this year because it's almost 100 percent certainty that this year will be even hotter than last year.

Yeah. And so the evidence rolled in throughout the year or the theories rolled in that were saying things like we're seeing less stuff going into the sky because of pollution controls. And so that's actually making the planet absorb more heat. You wrote about that, I think, in April. You talked about that on the show.

And then in October, you wrote about the role El Nino might have played in that. How might that actually have been involved in these record high temperatures last year? Yeah. So, you know, El Nino is long known as the major player in short term swings in temperature. What's been confusing about last year and going into this year is the pattern that we expect from how El Nino would boost temperatures is.

These years didn't quite follow that pattern, this pattern that's been established just really like the past few decades of modern observations. Temperatures kind of came on faster than a typical El Niño year, and they've also lingered a bit longer than a typical El Niño year. At the same time, that kind of sample is small, right, of just this historical record of the past few decades of how El Niño is.

There was this work a few months ago that kind of took every climate simulation that people have done that shows an unforced climate, just the earth kind of going on without greenhouse gas warming, just kind of naturally oscillating. Looked at all the El Ninos that popped up and how often you saw this kind of weird, unexpected jump

in temperatures, and it can happen. This kind of pattern could happen, they found, especially after you have a couple of years of La Nina, which is the opposite pattern in the Pacific. We swing to El Nino, then it became like a 10% likelihood that this type of jump could happen. So that was an indication of, hey, maybe El Nino is the actual major player beyond our inexorable increasing greenhouse gases and this kind of record-shattering new high.

So what about the radiation finding that we talked about in April, the idea that the Earth is just absorbing more because there's less pollution in the sky? Is that accounting for some of this increase in record in temperatures? Yeah, possibly. It's really hard to kind of tease it all out right now. Yes, you have kind of two different things intersecting where we have this kind of longer-ish term, like since like 2010 record showing that we're reflecting less light, so more light is kind of hitting Earth.

the planet. And what's driving that is a big question, though. Partially, I'm sure it's decreasing pollution. But the big question out there is if there's a change in the climate state or climate feedbacks, which would alter cloud behavior that, you know, is kind of unaccounted for or unknown. That is kind of one of the big uncertainties in climate science right now. Yeah. Yeah.

So you mentioned 2024 is on track to also break records? Yeah, it's nearly 100% certainty that it will be the warmest year now in the modern record. And, you know, we're swinging towards either a neutral state or maybe a La Nina, which will depress temperatures. So maybe you don't expect a, you know, a record the next year.

Who knows, though? There could be. It's, you know, the thing about the atmosphere is just really noisy. If you go to the ocean, you look at what's called ocean heat content. This is just the record of ocean heat, which sucks up 90% of the heat from global warming.

That rises year after year after year after year. There are no swings. There's no El Nino. That's really the best record of global warming we have, right? Not the atmosphere and surface temperatures. All right, Paul. So I wanted to also, just because this is the end of the year, you know, and you've written about so many amazing things. We've talked about asteroids, continental rifting, obviously climate change.

space exploration, any stories that stick out to you that looking back on your year that just really tickled you or that are really fascinating or fun? Yeah, you know, one particular, I love kind of finding new ways people are exploring past climate and paleo climate, you know, that can teach us a lot about the present day. And over the past few years, people have been

Looking at how they can use records from the wine industry, which go back to the 1300s, something like that, to actually get at paleoclimate records of temperature, precipitation. They've now developed where there's a way you can taste the sweetness of the grape juice that comes after it's crushed.

And people would rate it for tax purposes. Professional experts would rate it. You can use these numbers that these experts used, and they actually track variations in weather pretty well. And then you kind of add that up over time. And it might be something that can fill in the gaps on continental Europe in this period where you have this debate over how much there is like a medieval warm period or little ice age, things like this. All right. So the climate is in the wine and the ocean. Thank you.

Thank you very much, Paul. This has been really fun, and I can't wait to see what happens in 2025 in science. Yeah, me too. Paul Voussin is a staff writer for science. You can find a link to some of the stories that we talked about at science.org slash podcast.

Staff News Writer Dan Cleary is here to tell us about the year in fusion. So, Dan, welcome back to the podcast. We missed you. Thank you. Good to be here. You're always who I go to for realistic views on fusion. What happened this year with fusion energy as a potential source for everybody?

So, it's been a bit of a mixed thing. In the news, you get a lot of hype about what all these private fusion efforts are doing, but they're really yet to produce any real results. But most of the news in this past year was about government-funded efforts. At the beginning of the year, the first thing that really made an impact was the announcement of the last results from the joint European Taurus.

So this is one of those giant sort of donut-shaped reactors that use powerful magnets to hold the gas, the ionized gas, where the reaction takes place. For decades, JET was the biggest one in the world until it was recently overtaken by a Japanese tokamak.

But JET closed down at the end of 2023. But then in February, we got the results from their last experiments. And it broke its own record in terms of the amount of energy produced in a fusion reaction. They're able to keep the reaction going for around five seconds and produced 69 megajoules of energy, which in their estimation is enough to power 1,200 homes.

but just for five seconds. Yeah, exactly. But you also got to remember that the amount of energy they had to put in to make that reaction happen was more than that. So it's not yet a reaction that is producing more energy than it's taking to make it happen. So JETS basically lived its life, it did its contribution, and now they need to build something different. Is that what happened?

Yeah, pretty much. But also because things, you know, European researchers have other priorities, which we'll talk about in a second. But yeah, jet was very productive. As well as that final record, it was the first one to produce significant amounts of energy, which was back in 1997.

And it was adapted over the years. You know, in its last configuration, they made it as similar as possible to ITER, which is the giant reactor that's its successor, which

which is still being constructed. And they wanted to make something that was like a mini-Eater so that they could see how well the big thing might eventually perform. It's like passing the baton, right? You're like, oh, we're almost there. And then we're going to keep going in the form of Eater.

I think we had you on the show talking about running out of the preferred fuel for fusion. Yeah, well, that's still a big question. The stuff you're talking about is tritium, which is a heavy isotope of hydrogen. And it has a half-life of 12-something years, I think. So, you know, it doesn't hang around. You know, it doesn't exist naturally on Earth because any that was created billions of years ago is gone.

It's made in certain nuclear reactors in Canada and also a few abroad. And they produce tritium as a byproduct. So they're the main source of tritium in the world, the civilian world. There are also military sources of tritium, usually an adapted fission reactor to provide tritium for nuclear weapons because it's used to boost the yield of nuclear bombs.

We don't know much about how the military get their tritium, but they're not particularly happy to share. So the Canadian nuclear authorities are the place to go. And they're slowly closing down their CANDU reactors and their reserves are going to start to decay away, essentially. So, you know, there's a bit of a race on to get the first generation of commercial fusion reactors going because they're

A fusion reactor, the way people are designing them, will make their own fuel once they get started. They need a sort of starting inventory to get the thing going. But once it's operating, it should produce an excess of tritium. And then that'll continue to fuel that reactor, but also enable them to build more. So it's a complicated picture, but... I seem to remember a very dire looking graphic that was showing

how all these timelines intersect and kind of the race to bring these online before the fuel runs out so they can make more fuel so they can keep making more reactors. And it's

Even though building a reactor is incredibly slow, there's still somehow racing, right? Yeah, that's it. And that brings us very neatly on to talk about ITER, this giant fusion reactor, which is going to need kilograms of the stuff to operate. And I think the inventory of tritium that's available to civilian projects is only about 25 kilograms right now, and it's decaying. It'll be half that much in 12 years. So...

There isn't a lot of time, but that was another big announcement this year was that ITER is going to take longer to build than we thought. Its schedule for the past 10 years almost has been that it would be finished in 2025. Nobody believed that anymore because they had so many problems. It's not going to be finished in 2025, i.e. in one month from now, but is in fact going to be finished in 2034. Yeah.

So within a decade. Yeah, nine years later than currently scheduled. That'll just be operating with inert gas initially, so just hydrogen or just helium. And they'll work up towards power-producing reactions by 2039. You know what, though? That does give us time to build a nuclear reactor so we can make more tritium. Yes, yeah, well, that's true. But that's going to cost a lot of money, too. I don't know who's going to want to put that bill...

Another major event this year was just a glimpse of what is happening with the UK fusion. So in the UK, when Brexit happened, the UK decided not to remain part of the European fusion effort.

And they launched their own project. So they're planning to build an actual prototype power producing reactor, skipping a step. You know, other people are trying to just prove they can do it and then they will start generating power with the next machine. But the British government is going to build one that can actually put power onto the grid, though.

though it won't probably do so until the 2040s. So they're really pushing ahead. It's probably one of the most forward-looking national efforts to try and make fusion work. Right, because even if you, you know, if ITER comes online, gets going,

It's still an experimental reactor and it's not built to run for a lifetime and then supply and connect with a grid, right? Yeah, that's right. It is still an experimental machine. The timelines here are starting to look like 2050. As a complete not knower of this stuff, it still just looks like 2050. I mean, are solar and wind and water, are they going to just make this a little bit moot?

That's a very good question. And some people think so. Those technologies are just marching on and on and getting cheaper all the time and taking up a bigger share.

share of the world's generating capacity. Renewables are really getting to be quite a big thing. And also conventional nuclear. You know, a lot of countries are still building a lot of conventional nuclear reactors like China. It may be that we don't need fusion by the time someone figures out how to do it, but it's hard to predict. Renewables, apart from fission reactors, they have a problem with intermittency. You know, they don't

produce all the time. Things like reactors can just run 24-7. So they provide a sort of baseload power that you need to keep the world running, which is harder to do with intermittent sources. Although the battery people would argue. Yeah, exactly. You know, if someone figures out how to store energy in a really efficient and cost-effective way, then that'll change. I do think that's a cheaper experimental proposition. Yeah, I agree. Figure out how to...

pipe water up a hill or make a big battery, it's a little bit less intimidating financially than building a fusion reactor to test things out. Exactly. Yeah. So it's going to be interesting. Yeah, absolutely. But yeah, we'll definitely keep you posted. We'll keep checking in on it. All right, Dan, thank you so much. It's a pleasure. Daniel Clary is a staff writer for Science.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us at [email protected]. To find us on podcasting apps, search for Science Magazine, or you can listen on our website.

science.org slash podcast. This show was edited by me, Sarah Crespi, Megan Cantwell, and Kevin McLean. We had production help from Megan Tuck at Podigy. Our show music is by Jeffrey Cook and Wen Kui Wen. This year's news wrap-up music is Faster Does It by Kevin MacLeod. On behalf of Science and its publisher, AAAS, thanks for joining us.