Markus Andrews

Whenever rain or snow falls from the skies, a human-made chemical called trifluoroacetic acid (TFA) falls with it. Across the world, this chemical has shown up in lakes and rivers; bottled water and beer; cereal crops and animal livers; and even in human blood and urine1. And wherever researchers measure changes in TFA levels, they find that concentrations are rising.Over the past four decades, TFA levels have risen five- to ten-fold in the leaves and needles of tree species in Germany2,3. Researchers have also documented rising levels of TFA in Canadian Arctic ice cores4 and in groundwater in Denmark5.TFA accumulates partly because natural processes can’t break its strong carbon–fluorine bonds. By some definitions, TFA is the smallest example of per- and poly-fluoroalkyl substances (PFASs), which persist for so long that scientists have termed them forever chemicals (see ‘TFA: a controversial molecule’ and ‘Rising levels of TFA’).Some PFASs are already linked to higher risks of health harms and are banned internationally. Many countries are restricting the levels of certain PFASs in drinking water and embarking on costly clean-up operations.But the health impacts of TFA are less clear. The few animal studies that exist suggest that current levels are thousands of times lower than those shown to exert biological effects. The United Nations Environment Programme (UNEP), which has been assessing the risks of TFA since 1998, says it considers the chemical to pose minimal risk for now, and at least until 2100 — although UN member states last year asked it to re-evaluate its assessment.Source: Refs 2,3,5However, some countries have already begun clamping down on TFA. And in June 2024, two German federal agencies petitioned the European Chemicals Agency (ECHA) to label TFA as a reproductive toxin and a very persistent and very mobile substance. The ECHA has opened this petition for public comment, which closes on 25 July.In October 2024, worried European environmental scientists declared that rising levels of TFA could cause irreversible harm, calling the chemical a threat to ‘planetary boundaries’1. They support a widespread ban on all PFASs that the ECHA is considering — which covers TFA.But other scientists say that TFA shouldn’t be counted in the definition of PFASs, partly because it doesn’t build up in humans and animals as other PFASs do. The US Environmental Protection Agency, for instance, doesn’t currently consider TFA to be a PFAS.The stakes are high, because regulating TFA could have a far-reaching impact on powerful industries, such as the refrigeration, agrochemical and pharmaceutical sectors.Here, Nature explains the fight that’s brewing over this small but controversial molecule.Simple molecule, complex originsTFA enters the environment in many ways. It’s used in academic research, for example, to prepare peptides for biology studies, says Reza Ghadiri, a chemist at the Scripps Research Institute in La Jolla, California. More widely, however, the agrochemical, pharmaceutical and fine-chemicals industries use TFA as an ingredient to make larger fluorine-containing molecules, and it can escape from industrial facilities.In Germany, for instance, interest in TFA was sparked in 2016 after researchers at the German Water Centre (TZW) in Karlsruhe found high levels of the chemical in a river and traced it to a chemical plant.Industrial discharges are just one source of TFA pollution6. Other chemicals can also break apart to create TFA as they languish in the environment. These precursor chemicals include pesticides, PFASs leaching from discarded or landfilled consumer products and excreted medications that pass through sewage plants (see ‘TFA’s precursors’). This all adds TFA to terrestrial water, but not to rain; when water evaporates, TFA — like a salt — is left behind.The TFA in rain comes from different sources — mainly some fluorinated gases (F-gases), including those used as refrigerants and in building insulation. These gases leak from air-conditioner units and insulation foam, mostly when products are in use or being discarded.Scientific interest in TFA began after the Montreal Protocol came into force in 1989, when the world agreed to restrict gases including the chlorofluorocarbons (CFCs), used as refrigerants and aerosols, because they damaged Earth’s protective ozone layer.Industry users launched a massive effort called the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS) to assess the environmental impact of the F-gases that had been proposed as substitutes7. A few of those — including the widely used HFC-134a — were soon found to break up into TFA in the lowest layer of Earth’s atmosphere.Concerned that the F-gas substitution would introduce a foreign substance to the planet, researchers began studying TFA intensively. Unexpectedly, they discovered that TFA already existed in rain, springs and rivers at appreciable levels, suggesting that there were other sources. Indeed, later analysis of ice cores from the Arctic shows that TFA was deposited with snow there as long ago as 19694.The missing TFAThat kicked off a search in the 1990s for other TFA precursors. Surprisingly, these included anaesthetic gases that have been used since the 1950s, and that are exhaled or vented into the atmosphere.A twist in the tale emerged in 2002, when AFEAS-funded researchers measured substantial TFA in the Atlantic and Southern oceans8. In 2005, an international team of researchers found similar TFA levels in 22 spots in the Atlantic, Arctic and Pacific oceans. They extrapolated that the oceans held huge quantities of TFA — some 60 million to200 million tonnes9.That was far too much TFA to explain with known human-made sources. So, the authors of both studies suggested that TFA might be a naturally occurring salt in the oceans.Some industrial firms use this theory to argue that any anthropogenic TFA would wash away into oceans and increase the large amounts of natural TFA there by unnoticeable fractions. Panels of scientists convened by UNEP have leant on this argument repeatedly when concluding that TFA poses minimal risks at current environmental levels.But many scientists disagree that unexplained large amounts of TFA in the oceans must mean that it’s natural10. Measurements from a few locations should not be extrapolated to entire oceans, says Cora Young, an environmental chemist at York University in Toronto, Canada, whose team has documented TFA’s rising levels in Arctic ice cores (see ‘TFA in ice cores’)4.Source: Adapted from Ref. 4And no one has reported a plausible mechanism for TFA to form naturally, says Scott Mabury, an environmental chemist at the University of Toronto, who has identified precursors of TFA.David O’Hagan, a fluorine chemist at the University of St Andrews, UK, who studies naturally occurring fluorinated compounds, says that he remains “truly unsure” about whether TFA could occur naturally. A few microorganisms do make fluorinated molecules, but because these have only one fluorine atom — not three — O’Hagan doesn’t think microbial processes would create TFA. Scientists have yet to identify possible geological mechanisms, he adds.New data support the decades-old findings that the oceans could harbour large amounts of TFA. Last year11, the German environmental agency published measurements of TFA levels from 31 locations in the Atlantic Ocean that are higher than those reported in 2005 (it is too soon to tell whether ocean TFA is rising, however).But in the end, it doesn’t matter whether natural TFA exists in the oceans, says Finnian Freeling, an analytical chemist at TZW who performed both the Atlantic Ocean and German-tree studies. What’s important is the drastic rise in TFA levels on land. “These steep increases, they have to come from anthropogenic activities,” he says.Even if some TFA turns out to be naturally occurring, that doesn’t make it safe and doesn’t make it OK to add more, says Mark Hanson, an ecotoxicologist at the University of Manitoba in Winnipeg, Canada, who serves on the current UNEP panel.Researchers, including Shira Joudan, an environmental chemist at the University of Alberta in Edmonton, Canada, suggest that TFA emissions from sources other than F-gases have been underestimated.These researchers are investigating how much and how quickly precursors such as pesticides and pharmaceuticals break down into TFA. “If we’re going to make any decisions on limiting emissions, we need to know where it’s coming from,” Joudan says.Is TFA harmful?In the 1990s, AFEAS researchers concluded that TFA is not acutely toxic, by referring to earlier studies that had fed or injected TFA into mice and rats7. Huge quantities were needed to kill the animals, and by that metric, TFA was found to be “about as toxic as table salt”, says Thomas Cahill, an environmental toxicologist at Arizona State University in Tempe.TFA’s molecular structure differs from that of the well-established PFAS pollutants. The typical structure of the molecules linked to health harms has a hydrophilic head and a long hydrophobic tail swaddled in fluorine atoms. TFA has a mere stub of a tail, with just one fluorine-bearing carbon atom.For this reason, some scientists think that TFA shouldn’t even count as a PFAS. Because it is so small, TFA is highly water-soluble, allowing mammalian bodies to excrete it easily. In 1976, to check whether TFA is a harmful metabolite of the anaesthetic halothane, researchers injected two volunteers with TFA, and recovered all of it in urine within three days7. Many scientists think that TFA does not build up in organs and tissues, but instead behaves like a salt. “I view it like chloride,” says Mabury.Could the world go PFAS-free? Proposal to ban ‘forever chemicals’ fuels debateHowever, TFA levels could still rise in humans because the molecule is constantly consumed through food and water, and levels in those sources are rising, says Freeling. After measuring TFA in human urine samples, he thinks that dietary exposure is higher than many scientists assume. Cahill, who has found TFA in dozens of foodstuffs, agrees.And evidence is mounting that TFA can exert biological effects. In March, Ghadiri’s team reported, in a preprint, the accidental discovery that TFA is a bioactive component that lowers lipid and cholesterol levels in mice12. In a 1999 study, researchers observed that, as a laboratory contaminant, TFA inhibited the proliferation of certain bone cells in Petri dishes13. Ghadiri emphasizes that there is no human data on TFA; his takeaway is simply that it should not be treated as innocuous.Most significant are the animal data that German agencies are now relying on to convince the ECHA to label TFA as a reproductive toxin.In 2017, the ECHA told some firms that were registering TFA as a ‘high production volume’ chemical (to comply with updated European chemicals legislation) to provide more data on safety risks. That included data on reproductive toxicity, which the AFEAS hadn’t assessed. Industry groups commissioned safety studies from a contract lab that fed TFA to rats and rabbits and assessed their offspring; animals given more of the chemical had fetuses with lower weights and more deformities, particularly in the eyes, compared with those on lower doses. (The studies are not published, but the data were made public with the German petition.)However, those animals were given TFA at levels that are hundreds of thousands of times higher than researchers have measured in drinking water.Although these outcomes might not be seen in humans, the studies show that high levels of TFA could harm human health, says Jamie DeWitt, a toxicologist at Oregon State University in Corvallis. DeWitt is planning to start 30-day studies that expose mice to TFA through their skin, looking for effects on the immune system.Some researchers are more worried about the effects of TFA on plants and ecosystems. Plants take up TFA along with water through their roots, but the TFA doesn’t leave the plant together with transpired water vapour. “It can’t evaporate,” Cahill says. “It’s stuck.”How to get rid of toxic ‘forever chemical’ pollutionAFEAS researchers attempted to address these concerns in the 1990s by growing crops, including sunflower, wheat, maize (corn), rice and soya beans, in TFA-contaminated soil and water7. Apart from inhibiting growth at high levels (above 1 milligram per litre), the researchers largely found nothing.

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RESEARCH BRIEFINGS
11 June 2025

The mapping of lake surfaces globally has been constrained by the limitations of single-source satellite data. A spatio-temporal fusion approach now enables high-resolution mapping of more than 1.4 million lakes, revealing seasonality as the main factor driving changes in the spread of lake surfaces, with links between seasonality and human residence. More

Download the Nature Podcast 21 May 2025In this episode: 00:45 Treating mosquitoes for malariaResearchers have developed two compounds that can kill malaria-causing parasites within mosquitoes, an approach they hope could help reduce transmission of the disease. The team showed that these compounds can be embedded into the plastics used to make bed nets, providing an alternative to insecticide-based malaria-control measures, which are losing efficacy in the face of increased resistance.Research article: Probst et al.10:42 Research HighlightsThe sunlight-powered device that can harvest drinkable water from desert air, and evidence that the world’s richest people are disproportionately responsible for climate impacts.Research Highlight: Atacama sunshine helps to pull water from thin airResearch Highlight: The world’s richest people have an outsized role in climate extremes13:02 The genetics that can lead to pregnancy lossResearchers have found specific genetic mutations that can lead to pregnancy loss. It’s known that errors, such as the duplication of chromosomes, can lead to nonviable pregnancies but less has been known about non-chromosomal genetic errors. The new work identifies DNA sequence changes that can lead to a non-viable pregnancy. This may offer clinicians the ability to screen embryos for these changes to help avoid pregnancy loss.Research article: Arnadottir et al. 22:24 Briefing ChatBespoke CRISPR-based therapy treats baby boy with devastating genetic disease, and the ‘anti-spice’ compounds that can lower chillies’ heat.Nature: World’s first personalized CRISPR therapy given to baby with genetic diseaseNew Scientist: Chemists discover ‘anti-spice’ that could make chilli peppers less hotSubscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.Never miss an episode. Subscribe to the Nature Podcast on Apple Podcasts, Spotify, YouTube Music or your favourite podcast app. An RSS feed for the Nature Podcast is available too. More

RESEARCH HIGHLIGHT
16 May 2025

A device involving solar panels and a gel produces substantial amounts of water in one of the world’s driest deserts. More

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This February, 14 lorries set out from Wilmington, North Carolina, with a toxic cargo: more than 150 tonnes of grit-like carbon that had soaked up harmful chemicals from the city’s drinking water.The lorries took the carbon to one of the closest available ‘reactivation’ kilns, 1,200 kilometres north in Buffalo, New York. There, temperatures of nearly 1,000 °C burnt off the chemicals, breaking them into simple gas molecules, which were later turned into minerals. This month, the refreshed carbon will ride the lorries back down south.The manager of Wilmington’s drinking-water plant, Benjamin Kearns, says he checks the weather forecast for Buffalo all winter — fearing disruptions to his water-purifying operations, which depend on a carefully timed supply of fresh carbon every month. “If there’s a snowstorm, I am concerned,” he says.The carbon, technically called granular activated carbon (GAC), is at the heart of a US$43-million system that began operating in 2022 to rid Wilmington’s drinking water of PFASs, or per- and poly-fluoroalkyl substances. These synthetic chemicals now pervade the world — they’re used to make computer chips, lithium-ion batteries, medical devices, stain-resistant textiles and smudge-proof coatings, among many other products — and some of them endanger human health. Also known as forever chemicals, they resist natural destruction because of their strong carbon–fluorine bonds.Kearns’s plant is in the vanguard of an almighty remediation effort. In April 2024, the US Environmental Protection Agency (EPA) put strict nationwide limits on the concentrations of six PFASs in drinking water. The agency estimates that the rule will reduce PFAS exposure for around 100 million US residents.How best to get rid of PFASs is now a multibillion-dollar question. The EPA estimated that US utilities might have to spend up to $1.5 billion annually for treatment systems; an industry group that is suing the agency argues that costs could be up to $48 billion over the next 5 years. Utilities must have systems in place by 2029.European nations have rules restricting PFAS levels in drinking water, too. European Union rules take effect from 2026, but allow higher concentrations than the EPA does; however, countries such as Denmark and Germany have set stricter limits.The concern and the expectation of a booming market for cleaning up PFAS pollution has sparked a rush for better ways to capture and destroy forever chemicals. Although GAC does work — it is a porous material (or sorbent) that can trap and house pollutants — it doesn’t capture all PFASs equally well. Trucking carbon around so that the collected PFASs can be destroyed in reactivation kilns also exacerbates climate change, adds Frank Leibfarth, a polymer chemist at the University of North Carolina at Chapel Hill.Drinking water is filtered through nearly 4 metres of granular activated carbon in huge tanks at the Sweeney Water Treatment Plant.Credit: Cape Fear Public Utility AuthorityAnd although the EPA has focused on drinking water, scientists want to stop PFASs from ever reaching the water by removing them from other environmental sources. The industrial facilities that produce and use PFASs, ranging from fluorochemical manufacturers to paper and textile mills, often send their waste to municipal wastewater (sewage treatment) plants. But these aren’t usually equipped to remove PFASs, so their outflow adds forever chemicals into rivers. From there, the PFASs can reach drinking water directly or do so indirectly by infiltrating soils.The sludge that is left over from sewage treatment also accumulates PFASs. In some parts of the world, this nutrient-rich sludge, known as biosolids, has been spread onto farmland as fertilizer. In states such as Maine, farms that yield PFAS-tainted food have shut down. And a type of fire-fighting foam that is formulated with PFASs has contaminated soils and seeped into groundwater around military bases and airports worldwide, because of its frequent past use in fire-training exercises there.With looming deadlines, academic researchers and companies are developing methods to gather and destroy PFASs from these sources. “Loads of evolving techniques are out there,” says PFAS specialist Ian Ross at CDM Smith, an engineering firm in Boston, Massachusetts, that works on PFAS remediation.Capturing contaminantsOn the second floor of Kearns’s facility — the Sweeney Water Treatment Plant — drinking water held in up to eight concrete tanks sinks silently through nearly four metres of GAC. “It’s amazing how much carbon you need to treat for PFAS,” says Orlando Coronell, an engineer at the University of North Carolina at Chapel Hill who is collaborating with Leibfarth to test a new sorbent at the facility.Operated by the Cape Fear Public Utility Authority (CFPUA), this plant serves 200,000 people in the coastal city of Wilmington. It draws water from the Cape Fear River, which in 2017 was shown to have high levels of one of the six EPA-regulated PFASs, called GenX (see ‘Cape Fear and PFAS pollution’). The molecules had come from 160 kilometres upstream, where fluorochemical manufacturer Chemours makes PFASs for electronics and battery manufacturing, among other uses, and had discharged them into the river.Source: RTI International (Adapted from https://go.nature.com/429E3DL)After the CFPUA installed the sorbent system, levels of GenX and several other PFASs fell (and are below the new EPA limits). While the system was being designed and constructed, North Carolina’s state environmental agency sued Chemours, and a local non-profit group added pressure by suing both organizations together. The parties agreed to settle: Chemours denied wrongdoing, but installed better controls on its PFAS emissions, including a 1.6-kilometre-long underground barrier wall paired with a GAC filtering system that collects surface and groundwater near the plant and removes PFASs. The firm says it has invested more than $400 million at its plant to remediate PFAS emissions and limit future ones. The CFPUA is currently suing Chemours to pay for the Sweeney filtration system.GAC is generally effective, but it is a ‘broad-spectrum’ sorbent that traps everything it attracts into its hydrophobic (water-repellent) pores, not just PFASs, says Coronell. The Sweeney plant receives water with much higher levels of dissolved organic matter than of PFASs, which compete for space in GAC’s pores. The six molecules on the EPA’s list stick well enough, but any PFAS with a shorter, hydrophobic fluorine-bearing tail does not. As GAC’s pores fill up, short-chain PFASs can break through the pores and re-enter drinking water.In particular, ultrashort-chain PFASs (those with a three-carbon fluorinated tail or shorter) are worrying researchers(see ‘PFAS pollutants’), because the molecules are being found in waters downstream of Chemours and near semiconductor manufacturing facilities1. After the CFPUA detected two ultrashort PFASs in its drinking water after treatment, it began switching out the GAC about every 200 days, instead of the roughly 300 days it had used when capturing GenX. That has almost doubled its carbon-regeneration costs.Other established ways to capture PFASs have pros and cons. A type of sorbent called ion-exchange resin traps contaminants broadly through electrostatic interactions: the six EPA-regulated PFASs all carry a negative charge, and they stick by trading places with a negatively charged component on the resin.Less resin is needed to treat the same amount of water than with GAC, but it costs five to six times more, says Detlef Knappe, an environmental scientist at North Carolina State University in Raleigh. Nitrate salt ions in the water can clog the resin and reduce its cost-effectiveness, and the resins are used just once in drinking-water facilities, because cleansing them often involves washing in methanol, an unacceptably toxic solvent.Another method uses membranes to separate contaminants from water. In reverse osmosis, mechanical pressure forces water through a membrane with tiny pores: water that is almost pure passes through, while everything else stays on the other side in a gradually saltier mix. Membrane systems are more expensive to build — reverse osmosis was three times the cost of a sorbent system when the CFPUA evaluated the options. (But if sorbents had to be changed more frequently, then membrane systems would become cost-effective, says Knappe.) Reverse osmosis also generates massive volumes of a watery, PFAS-laced brine that is difficult to manage.Targeted PFAS trapsMany researchers are inventing sorbents that can trap PFASs more selectively, often involving multiple chemical interactions at once. On the first floor at the Sweeney plant, beneath the GAC tanks, Coronell and Leibfarth are testing a proprietary sorbent. So far, it has lasted three times as long as the CFPUA’s GAC and 40% longer than a top-performing ion-exchange resin before the short-chain molecules have broken through. One possibility, says Kearns, is to add a layer of a new sorbent to capture escapees from GAC, thereby lengthening the time between trips to the reactivation kiln.Some researchers are testing their sorbents on dirtier, more complex PFAS sources, such as wastewater. The dirtiest of all is the liquid that pools at the bottom of a landfill (landfill leachate), which must be pumped out and treated, often by being transported to the nearest wastewater treatment plant by lorry. “It’s pretty gross,” says William Dichtel, a chemist at Northwestern University in Evanston, Illinois, who plans to test a sorbent on the leachate.In general, sorbents capture long-chained PFASs better than short-chained ones. Costly membrane systems might prove necessary for waters enriched in short-chained PFASs: one study2 found that nanofiltration, which uses membranes with slightly larger pores and produces less waste than reverse osmosis, captured more than 90% of ultrashort-chain PFASs from semiconductor wastewater.Another idea is to reconfigure GAC itself. The material’s pores are irregularly shaped, but carbon chemist Pan Ni at the University of Missouri in Columbia and his colleagues have reported preliminary work at a conference suggesting that the pores could be aligned into nano-sized channels instead. With the right channel diameters, GAC might begin targeting just the short-chained molecules.Destroying captured PFASsEvery sorbent eventually becomes full. How best to destroy the accumulated PFASs is now a key question and a billion-dollar market.Utilities that choose to clean their water using GAC could follow the Sweeney example and drive it to a reactivation kiln. An alternative is incineration, which is also a common way to dispose of spent single-use resins. Incineration simply destroys materials by burning them in the presence of oxygen — “a runaway reaction”, says Knappe — whereas GAC reactivation is controlled and works without oxygen.Ideally, both kinds of treatment would break every carbon–fluorine bond and release fluorine as hydrogen fluoride gas. The gas could then pass through ‘scrubbers’ containing alkaline reagents similar to baking soda to convert it into harmless minerals such as sodium fluoride.But it is not clear that the PFASs are completely mineralized, because some laboratory studies can’t match up the mass of the fluorine going in with that recovered from the products3. This suggests that some PFASs might have been broken up only into smaller gaseous PFAS molecules, which are harder to capture and might be spread into the air.Such gases can, however, be captured with the types of filter already installed at incinerator facilities that routinely deal with hazardous waste, says AnnieLu DeWitt, an analytical chemist at Clean Harbors, a waste-management firm headquartered in Norwell, Massachusetts, that specializes in hazardous-waste incineration and landfill.Tests in which PFASs were incinerated with added calcium minerals suggest that fluorine gets locked effectively into calcium fluoride. In Australia, some PFAS-containing wastes have been fed to cement kilns, which run at high temperatures and contain lots of calcium. However, total mineralization remains unproven.Because of questions over the effectiveness of incineration, the US Department of Defense has temporarily forbidden its facilities from incinerating fire-fighting foam that has high concentrations of PFASs. The department is working with the EPA and Clean Harbors to check whether incineration produces some PFAS gases. If not, the expectation is that incineration will become the go-to technique, says Ross. In the meantime, a bevy of start-up firms, often spun out of academic labs, have developed alternative ways to destroy PFASs. Many of these use high-energy conditions to rip the molecules apart. The firms say that the techniques can treat fire-fighting foam and PFAS-laced brines or biosolids that aren’t suitable for incineration.Vials of samples containing GenX, a PFAS chemical, in an EPA analysis lab in Cincinnati.Credit: Joshua A. Bickel/AP/AlamyA Pennsylvania start-up firm called OnVector uses plasmas (ionized gases) to break the molecules apart, while the company 374Water in Morrisville, North Carolina, uses supercritical water (water that behaves like a gas and a liquid, owing to high pressure and temperature). A technique being commercialized by Aquagga, a firm in Washington state, uses water at a lower temperature and pressure than other firms do, but adds an alkali chemical to kick-start the PFAS destruction.Milder destruction methods

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“I’m an electrical engineer, but I think the most important connections are those between humans. This is what drives my work managing Monitoreo De Agua En Colombia (Water Monitoring in Colombia) a project at the University of the Andes in Bogotá. In Colombia, many rivers are contaminated, for example with mercury used in illegal gold mining. Through this project, the university’s engineering students work with groups in remote areas to co-design water probes, such as the one I’m using in the picture.I lead this project alongside my research using nanotechnology to create innovative materials for energy applications. Utilizing my engineering skills and resources to make humanitarian technologies for people here in Colombia is a hugely satisfying and important part of my job.In this picture, taken last November, I’m demonstrating how to use a custom-designed probe to record the pH, conductivity, dissolved-oxygen level and temperature of the water. We upload the results to our website to form a publicly accessible data set that shows the safety of water across the country. As of February, we have worked with 8 communities and have made around 50 probes. I am proud that this project is open science, so that any community can build a probe for themselves.

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A lander and an orbiter are on their way to the Moon to look for water at the lunar south pole (pictured).Credit: Alan Dyer/VW PICS/Universal Images Group via GettyTwo US spacecraft launched to the Moon today from Florida’s Cape Canaveral, on their way to hunt for water that scientists think exists at the lunar south pole. What the craft finds could have big ramifications for NASA’s plans to send astronauts to this part of the Moon in the coming years.Moon mission failure: why is it so hard to pull off a lunar landing?One of the missions is a commercial lander; it aims to touch down closer to the Moon’s south pole than any previous mission, carrying NASA instruments including an ice-hunting robot drill. The other spacecraft, NASA’s Lunar Trailblazer, is an orbiter with the goal of producing the highest-resolution maps of water on the Moon.Lunar water could provide a resource for expanded lunar exploration, such as by supplying the raw ingredients for rocket fuel at Moon bases. Scientists have known since 2009 that such water exists, but they want to know much more about where it is and how much there is. The two new spacecraft “are going after really important pieces of that puzzle,” says Parvathy Prem, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who is not affiliated with either mission.The lander is expected to touch down on 6 March. It is the second attempt by Intuitive Machines, a company based in Houston, Texas, whose first lunar spacecraft tipped over on landing last year.Lunar Trailblazer will take a leisurely trajectory and reach the Moon in several months. If all goes well, it will enter its final science-mapping orbit around August.Searching for waterMany space agencies and scientists are keen to learn more about water at the lunar poles, which hold a geological record of the Solar System’s early history. The Indian mission Chandrayaan-2 is currently orbiting the Moon and building up its own data on where water might exist, as is a Korean probe that carries a NASA instrument to peer into shadowed, potentially ice-rich craters.Intuitive Machines’ new lander, named Athena, is headed for the Mons Mouton region of the Moon. Researchers think there is water in the lunar soil there, perhaps bound up in minerals or in pores in the soil.These six countries are about to go to the Moon — here’s whyAthena will search for water in several ways, including the use of NASA’s ice-mining drill, TRIDENT. If Athena lands successfully, operators will command TRIDENT to penetrate the lunar soil, drilling up to one metre deep to pull up the soil and leave it in a crumbly pile on the surface. A mass spectrometer on board will analyse the pile for signs of water or other volatile substances that might be escaping as gases. That ability to drill and analyse simultaneously provides “critical data on how lunar soils behave”, says Jackie Quinn, the drill’s project manager at NASA’s Kennedy Space Center on Merritt Island, Florida.

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