00:46 Physicists spot new types of high-energy radiation in thunderstorms
Physicists have identified new forms of γ-ray radiation created inside thunderclouds, and shown that levels of γ-ray production are much higher on Earth than previously thought.
Scientists already knew about two types of γ-ray phenomena in thunderclouds — glows that last as long as a minute and high-intensity flashes that come and go in only a few millionths of a second. Now, researchers have identified that these both occur more frequently than expected, and that previously undetected γ-ray types exist, including flickering flashes that share characteristics of the other two types of radiation.
The researchers hope that understanding more about these mysterious phenomena could help explain what initiates lightning, which often follows these γ-ray events.
Research Article: Østgaard et al.
Research Article: Marisaldi et al.
Nature: Mysterious form of high-energy radiation spotted in thunderstorms
10:00 Research Highlights
Ancient arrowheads reveal that Europe’s oldest battle likely featured warriors from far afield, and why the dwarf planet Ceres’s frozen ocean has deep impurities.
Research Highlight: Bronze Age clash was Europe’s oldest known interregional battle
Research Highlight: A dwarf planet has dirty depths, model suggests
12:09 A complete wiring diagram of the fruit fly brain
Researchers have published the most complete wiring diagram, or ‘connectome’ of the fruit fly’s brain, which includes nearly 140,000 neurons and 54.5 million connections between nerve cells.
The map, made from the brain of a single female fruit fly (Drosophila melanogaster), reveals over 8,400 neuron types in the brain, and has enabled scientists to learn more about the brain and how it controls aspects of fruit fly behaviour.
The FlyWire connectome: neuronal wiring diagram of a complete fly brain
Nature: Largest brain map ever reveals fruit fly’s neurons in exquisite detail
22:16 Briefing Chat
How researchers created an elusive single-electron bond between carbon atoms, and why bigger chatbots get over-confident when answering questions.
Nature: Carbon bond that uses only one electron seen for first time: ‘It will be in the textbooks’
Nature: Bigger AI chatbots more inclined to spew nonsense — and people don’t always realize
Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.
The dwarf planet Ceres hosts a frozen ocean that is almost pure water ice at its surface and becomes ‘dirtier’ with depth, modelling suggests1. The work reconciles conflicting evidence regarding the ice content of Ceres.
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Technicians prepare to install Europa Clipper’s 3-metre-wide antenna on the spacecraft on 17 June at the Kennedy Space Center in Cape Canaveral, Florida.Credit: NASA/Kim Shiflett
After decades of dreaming of Jupiter’s moon Europa — and the vast ocean that probably lies beneath its icy surface — scientists are now weeks away from sending a spacecraft there. NASA confirmed yesterday that its Europa Clipper mission will launch on schedule, following a scare that it might have to be significantly delayed owing to possibly faulty transistors installed on the US$5-billion spacecraft.
“We are confident that our beautiful spacecraft and capable team are ready for launch operations and our full science mission at Europa,” Laurie Leshin, the director of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, said at a 9 September press conference.
With a mass of more than 3.2 tonnes, a height of roughly 5 metres, and a width of more than 30 metres with its solar panels fully unfurled, Europa Clipper is the largest spacecraft that NASA has ever built for a planetary mission. Yesterday, the mission passed what’s known in NASA parlance as ‘key decision point E’ — the final review hurdle that needs to be cleared before proceeding towards launch. The spacecraft’s launch window opens on 10 October.
Jupiter’s moon Europa has an icy surface and few craters.Credit: NASA/JPL-Caltech/SETI Institute
If it takes off successfully next month, the orbiter will arrive at Jupiter in April 2030. Its nine instruments will then investigate both Europa’s icy crust and the ocean that scientists suspect lies beneath it, to determine whether the moon could support life as we know it. Previous missions have suggested1 that Europa’s icy surface hides a subterranean ocean of brine with more than twice the volume of water in Earth’s oceans. The moon’s fissured, seemingly young surface also implies that the satellite has active geology — hinting that Europa’s interior could be warm and dynamic enough for the complex chemistry of life.
There’s no such thing as a tricorder — a fictional instrument from the Star Trek universe — that we can aim at something to reveal whether it is alive, said Curt Niebur, the Europa Clipper programme scientist at NASA’s headquarters in Washington DC, during the press conference. “It is extremely difficult to be able to detect life, especially from orbit,” he said. “First, we’re going to ask the straightforward question: Are the proper ingredients there for life to exist?”
Choppy waters en route to an ocean world
Before the transistor scare, Europa Clipper had endured its share of setbacks. In 2019, NASA angered scientists by cutting a sophisticated magnetometer from the spacecraft, citing budget concerns. The mission also endured uncertainty for years over how it would get to space. That’s because the US Congress had long mandated that the spacecraft fly aboard NASA’s long-delayed Space Launch System rocket. Finally, in 2020, US lawmakers allowed the programme to select the reliable Falcon Heavy rocket from private firm SpaceX in Brownsville, Texas, for the launch.
Violent volcanoes have wracked Jupiter’s moon Io for billions of years
The possible transistor problem reared its head in May this year when NASA engineers learnt that batches of a certain kind of transistor already installed on the Europa Clipper spacecraft were misbehaving. The components, called MOSFETS (metal-oxide-semiconductor field-effect transistors), act like switches in electrical circuits. They came from a NASA supplier, the company Infineon, based in Neubiberg, Germany.
Because Europa Clipper is set to fly past Europa 49 times, at distances as close as 25 kilometres, the spacecraft will also need to fly through a fusillade of charged particles accelerated by Jupiter’s magnetic field, which is roughly 20,000 times as strong as Earth’s. This means that the electronics housed in the orbiter must resist radiation damage.
But in May NASA said it was examining whether the mission’s transistors risked malfunctioning. The agency launched into four months of 24-hour intensive testing at three different facilities: JPL; the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland; and the NASA Goddard Space Flight Center in Greenbelt, Maryland. “This was a huge lift, and I think ‘huge lift’ is a huge understatement,” Leshin said.
After evaluating spare MOSFETs from the same batches that were installed on Europa Clipper, NASA found that the spacecraft’s circuits would perform as expected. This conclusion partially rests on the fact that during the first half of its four-year baseline mission orbiting Jupiter, the spacecraft will be in the worst of Jupiter’s radiation only one out of every 21 days. The rest of the time, the orbiter’s transistors can partially self-heal from radiation damage when gently heated, via a process called annealing.
“While Europa Clipper does dip into the radiation environment, once it comes out, it comes out long enough for those transistors the opportunity to heal and partially recover between flybys,” said Jordan Evans, the Europa Clipper project manager at JPL during the conference. “We can — I have high confidence, and the data bears it out — complete the original mission.”
The Moon probably originated from material scattered into space when a large impactor struck the newly formed Earth.Credit: David Gannon/AFP via Getty
India’s Chandrayaan-3 mission has obtained the first measurements of the composition of the soil near the Moon’s south pole1. The minerals found offer further evidence that the lunar surface was entirely molten shortly after the Moon formed.
Chandrayaan-3’s Vikram lander touched down on 23 August 2023. It released a rover called Pragyan, which collected data ranging from temperature to seismological measurements over 10 days.
India’s Moon mission: four things Chandrayaan-3 has taught scientists
Pragyan also studied the chemical composition of the regolith: the fine material that covers much of the lunar surface. The rover stopped and deployed an instrument called an alpha-particle X-ray spectrometer (APXS) 23 times.
Santosh Vadawale, an X-ray astronomer at the Physical Research Laboratory in Ahmedabad, India, and his colleagues analysed radiation data collected by the APXS, and used this information to identify the elements in the regolith and their relative abundances, which, in turn, revealed the soil’s mineral composition. The team found that all 23 samples comprised mainly ferroan anorthosite, a mineral that is common on the Moon. The results were reported in Nature today.
“It’s sort of what we expected to be there based on orbital data, but the ground truth is always really good to get,” says Lindy Elkins-Tanton, a planetary scientist at Arizona State University in Tempe.
Previous landers obtained similar results. However, the Chandrayaan-3 samples are the first from the subpolar region: previous landers visited equatorial and mid-latitude zones. Together, this suggests that the composition of the regolith is uniform across the Moon’s surface.
Vadawale says that this is direct confirmation that the lunar surface was a molten magma ocean immediately after it formed. The lunar magma ocean theory was first proposed by two independent groups in 1970, after rock collected during the 1969 Apollo 11 landing was analysed.
Moon’s origin
The best model for the origin of the Moon is that the newly formed Earth was struck by a large impactor, called Theia, which vaporized the planet’s surface and blasted a large amount of material into orbit. The scattered material swiftly accreted to form the Moon. This impact theory explains why lunar rocks have an isotope composition similar to those on Earth.
The material that formed the Moon had a lot of energy, which had to be dissipated. It escaped in the form of heat and, as a result, the young Moon’s surface melted into a magma ocean. Dense mafic rocks, rich in metals such as magnesium, sank into the Moon’s interior. Lighter rocks, including anorthosite, floated to the top, forming highlands similar to those visited by Chandrayaan-3.
“It gives more support to the lunar magma ocean hypothesis,” says Mahesh Anand, a planetary scientist at the Open University in Milton Keynes, UK.
Vadawale and his colleagues found that their samples contained elevated levels of magnesium compared with those of calcium. This suggests that deeper mafic material has been mixed into the regolith.
The researchers attribute this to the events that formed a huge crater called the South Pole–Aitken basin, the rim of which is 350 kilometres from Chandrayaan-3’s landing site. “When such a large impact basin forms, it is supposed to excavate some deeper material,” says Vadawale, because the impactor drives deep into the crust. This deeper, magnesium-rich material would have been scattered over a huge area, slightly altering the make-up of the regolith Pragyan sampled.
But one problem with that idea is that the South Pole–Aitken basin seems to be dominated by a mineral called pyroxene, which doesn’t quite fit Pragyan’s data, says Anand. Resolving this will probably require samples to be brought back to Earth, he says.
The next Chandrayaan mission, which is in an early phase of development, intends to do just that.
“To me, it’s a story about the success of the Indian space programme,” says Elkins-Tanton.
The Jupiter Icy Moons Explorer spacecraft approaching Earth (artist’s impression).Credit: ESA/Lightcurve Films/R. Andres
Next week, the Jupiter Icy Moons Explorer (JUICE) probe will whip past both the Moon and Earth on its way to deep space, as part of a daring and previously untried double fly-by manoeuvre.
The European Space Agency (ESA) mission is one year into its elaborate eight-year journey and will eventually visit three of Jupiter’s moons. The craft will harness the gravity of Earth, the Moon and Venus to reach Jupiter using as little fuel as possible.
On 19 and 20 August, the mission will fly past the Moon and Earth in rapid succession, performing the first-ever double gravity-assist manoeuvre. JUICE will first reach the Moon, harness the lunar gravity to brake and change course and then swing around Earth a day later, further altering its speed and direction. There is no plan to readjust its trajectory between the fly-bys.
Source: ESA
The Moon is usually treated as a perturbation to factor into account when spacecraft slingshot around Earth, but harnessing its pull can save propellant. The lunar gravity-assist technique, combined with the timing of JUICE’s launch in April last year, will save enough fuel to allow the probe to orbit Jupiter’s moon Ganymede at just 200 kilometres in 2035, at the end of the mission. “That’s great news in terms of the science,” JUICE mission analyst Arnaud Boutonnet, at the ESA European Space Operations Centre (ESOC) in Darmstadt, Germany, told reporters at a press conference last Friday.
Jupiter mission will be first to orbit moon of another planet
The double gravity-assist move is risky, because each fly-by will amplify any errors in the craft’s trajectory. “It’s like passing through a very narrow corridor, very, very quickly: pushing the accelerator to the maximum when the margin at the side of the road is just millimetres,” said the mission’s spacecraft-operations manager, Ignacio Tanco at ESOC, in a statement. But performing the manoeuvre close to home will be an opportunity to test whether JUICE’s scientific instruments are working as planned, in an environment that researchers know well, said Claire Vallat, operations scientist for the mission at ESA in Madrid, at the briefing. “This is a unique opportunity to study those instruments.”
The spacecraft’s circuitous route is by design. The Earth–Moon fly-by will slow down JUICE and deflect its course on a shortcut towards Venus. JUICE will gain energy as it swings around Venus, and two further gravity assists from Earth — in 2026 and 2029 — will eventually sling the craft out towards Jupiter.
Takao Doi, an astronaut and engineer at Kyoto University, holds the world’s first wooden satellite.Credit: Kota Kawasaki/Yomiuri Shimbun via AP/Alamy
Researchers unveiled the world’s first wooden satellite last month, billing it as clearing a path for more uses of wood in outer space. The material will be more sustainable and less polluting than the metals used in conventional satellites, they say.
Researchers at Kyoto University in Japan and the Tokyo-based logging company Sumitomo Forestry showed off the satellite, called LignoSat, in late May. The roughly 10-centimetre-long cube is made of magnolia-wood panels and has an aluminium frame, solar panels, circuit boards and sensors. The panels incorporate traditional Japanese wood joinery methods that do not rely on glue or metal fittings.
Wood might seem counterintuitive for use in space because it is combustible — but that feature can be desirable. To curb the growing problem of space junk threatening spacecraft and space stations, rocket stages and satellites are deliberately plunged into the Earth’s atmosphere to burn up. But during combustion, they release particles of aluminium and other metals. Many more spacecraft launches are planned, and scientists have warned that the environmental effects of this pollution are unknown.
When LignoSat plunges back to Earth, after six months to a year of service, the magnolia will incinerate completely and release only water vapour and carbon dioxide, says Takao Doi, an astronaut and engineer at Kyoto University, who is part of the research team. He points to other benefits of wood: it’s resilient in the harsh environment of space and does not block radio waves, making it suitable for enclosing an antenna.
And there is a precedent for spacecraft with wooden parts. Launched in 1962, NASA’s Ranger 3 lunar probe had a balsa-wood casing intended to protect its capsule as it landed on the lunar surface (the probe malfunctioned, missed the Moon and began orbiting the Sun).
Timber pioneers
LignoSat will cost about US$191,000 to design, manufacture, launch and operate. Sensors onboard will evaluate strain on the wood, temperature, geomagnetic forces and cosmic radiation, as well as receive and transmit radio signals. The satellite has been handed over to the Japan Aerospace Exploration Agency (JAXA) and will be transferred to the International Space Station in September, before being launched into orbit in November.
Growth has been slow for the project, which began in 2020 with speculation about the wider potential for wood in space for better sustainability.
“In our first conversations, Dr Doi proposed we build wooden housing on the Moon,” says team member Koji Murata at the biomaterials-design laboratory at Kyoto University’s Graduate School of Agriculture. “We have also discussed the possibility of building domes on Mars out of wood in order to grow timber forests.”
Martian and lunar colonists, like all pioneers, would have to make use of local materials — regolith (rocky material on the surface), silicon dioxide and other minerals, in the case of Mars. But wood could play a part in crafting temporary or permanent shelters. Murata points to plans by JAXA and industrial partners to develop shelters made partly of wood that could be used in Antarctica or on the Moon.
“The natural radiation-shielding properties of wood could be used effectively to design walls or outer shells of space habitats to provide protection,” says Nisa Salim, who specializes in engineered materials at Swinburne University of Technology in Melbourne, Australia, and is not part of the project. “Wood is an effective insulator, capable of regulating temperature and minimizing heat transfer to maintain a comfortable indoor environment. Wood is easy to work with, renewable and biodegradable, aligning with sustainability goals for space exploration.”
Salim noted that the structural integrity, safety and longevity of wood need to be confirmed in space.
Wood consists of cellulose held together by lignin, a kind of organic polymer. That makes it a naturally occurring member of the class of materials known as composites, says Scott J McCormack, a materials engineer at the University of California, Davis, who is not involved in the project. Composites are often used in the aerospace industry, so he does not find it surprising that their use in satellites might be explored.
“Composites are ideal for the aerospace industry — and also satellites — due to their high strength-to-weight ratio,” says McCormack. But he has doubts about how wood will fare as a structural material on the Moon or Mars. “The first concern that comes to mind is galactic cosmic radiation [GCR] and how it might degrade the mechanical properties of wood over time. GCR isn’t that big of problem for us here on Earth, thanks to our atmosphere.”
But Murata says that the team has studied measurements of GCR and solar energetic particles — high-energy particles that are released from the Sun — taken by NASA’s Curiosity rover on Mars, as well as the effects of gamma rays on wood on Earth. He thinks that wood on Mars could potentially last for thousands of years. “Radiation on Mars is a big problem for living organisms, including humans,” he says. “I don’t think this is going to be much of an issue for wood.”
China’s Chang’e-6 robotic Moon-lander has wrapped up two days of drilling into the surface of the far side of the Moon and the ascender has blasted back into space. The spacecraft, with its precious rock samples, is now in lunar orbit, waiting to dock with the orbiter for the trip back home. It is the first time samples have been taken from the far side of the Moon.
The Chang’e-6 lander made a successful touch-down on the Moon early on Sunday morning (Beijing time) at a pre-selected site within the South Pole-Aitken (SPA) basin, the oldest and largest lunar impact basin. Since then, Chang’e-6 has autonomously deployed its drill and scoop to collect soil and lunar regolith — the rocky material covering the surface of the Moon. Together the samples are expected to weigh up to two kilograms. “The sampling process has gone very smoothly,” says Chunlai Li, the mission’s deputy chief designer at the National Astronomical Observatories in Beijing.
With the specimens loaded and sealed, the ascender fired its engine at 7:38 am Tuesday morning to lift off from the landing site and reached the designated lunar orbit six minutes later, according to the China National Space Administration (CNSA).
“China is successfully carrying out complex operations on the lunar far side,” says Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. “The launch of the ascent stage was the first time anyone has taken off from the far side.”
Captivating basalt
According to Li, Chang’e-6 precise landing location is 41.63 degrees south and 153.99 degrees west, which means that the samples will mainly consist of basalts — dark-coloured, cooled lava. Similar material has previously been brought back to Earth for analysis from the Moon’s near side.
The age of the basalts is estimated to be around 2.4 billion years old—much younger than the SPA basin itself, says planetary geologist Alfred McEwen at the University of Arizona, Tuscon. “There should also be fragments of older rocks in the regolith they collected,” McEwen says.
What China’s mission to collect rocks from the Moon’s far side could reveal
Scientists hope to use samples returned from the SPA to precisely measure the basin’s age, and improve their understanding of the early history of the Earth and other planets, notes planetary geologist Jim Head at Brown University, in Providence, Rhode Island.
Regardless of whether this information can be gleaned from the samples, the scientific value of Chang’e-6 samples, if successfully returned, will be very high, he says. They will be the first rocks ever retrieved from the Moon’s far side, which is dramatically different from the near side. “Obtaining dates and compositional information from the many hundreds of fragments sampled by the Chang’e-6 drill and scoop is like a having treasure chest full of critical parts of lunar history, and will very likely revolutionize our view of the entire Moon,” he says.
Rock then dock
In the coming days, Chang’e-6 will face one of the trickiest parts of the whole mission — rendezvous and docking of the ascender with the orbiter and transferring the samples, says McDowell. “You have two robots orbiting the Moon separately at 5,900 kilometres per hour, which have to come together and touch each other gently without crashing into each other,” he says.
The Chang’e-6 samples’ trip home is expected to last about three weeks, ending with a return capsule piercing through Earth’s atmosphere and landing in the grasslands of the Siziwang banner in northern China’s Inner Mongolia autonomous region around 25 June.
Planetary scientist Michel Blanc at the Research Institute in Astrophysics and Planetology, in Toulouse, France, who watched the launch of Chang’e-6 on Hainan island a month ago and followed the key steps of the mission, says that the scientific impact of the mission cannot be over-emphasized, because it will not only bring the first sample from the lunar far side, but also from one of the lowest-altitude regions of the Moon, where the surface might be closest to the mantle.
“We planetary scientists are crossing fingers for the success of the rest of the mission,” Blanc says.
NASA astronaut Kate Rubins was having a hard time seeing in the eerie twilight of the Moon’s south pole this month.
Rubins made her way carefully through the deep shadows on the lunar surface, her path dimly lit by lights on her spacesuit’s helmet. She was hunting through the volcanic landscape for geological treasure — Moon rocks that she could pick up and bring back to Earth, which would reveal secrets of this frozen world. As the first person to set foot on the Moon in more than half a century, Rubins was making good progress on her historic foray — despite the piles of cow manure along the way.
The rock-strewn plain wasn’t really the Moon but was, in fact, the high desert of northern Arizona. Rubins and astronaut Andre Douglas were participating in the biggest dress rehearsal yet for the next time NASA plans to send people to the Moon’s surface, a mission known as Artemis III. If all goes to plan, Rubins or one of her colleagues will be stepping onto the actual Moon a little over two years from now. So NASA is training its astronauts to make the most of their precious time there — given that no human has set foot on the lunar surface since the last Apollo crew blasted off in 1972.
The $93-billion plan to put astronauts back on the Moon
“There’s a lot we need to relearn or figure out,” says Juliane Gross, a planetary scientist at NASA’s Johnson Space Center (JSC) in Houston, Texas, who will oversee the Artemis samples when they come back to Earth. “And so we’re charting the way while we sail it.”
“We’re baking in that scientific rigour very early on that these missions are going to need,” Rubins later told Nature.
During the moonwalking simulation two weeks ago, Gross and other scientists gathered at JSC. It was a massive undertaking that linked astronauts in the field in Arizona with mission controllers and a science team in Houston — working together in real time to choreograph what the astronauts should do on the mock lunar surface. Leading scientists, famous astronauts and NASA brass all showed up to witness the historic test. More than six years after the agency officially kicked off its Artemis programme to return humans to the Moon, it felt as if the Artemis Moon landing was becoming real.
Geology class
If NASA manages to pull off an Artemis III landing, it will have taken some US$100 billion to develop the rockets, crew capsule, landing system and other equipment. As with the Apollo 11 landing in 1969, in which Neil Armstrong and Buzz Aldrin became the first people to set foot on the Moon, the Artemis III landing aims primarily to get astronauts there and back safely.
But science is an integral part of the Artemis programme, according to NASA. The agency has ramped up its astronaut training to incorporate more field geology, so that crew members can learn how to explore the lunar landscape and determine which rocks to pick up, as well as how to deduce the area’s geological history.
Such training paid off during the final three Apollo missions, when each astronaut had roughly 1,000 hours of science training, says Dean Eppler, a lunar geologist who has retired from JSC. “We look at Apollo as the way to do it because it was very successful,” he says. On Apollo 15 in 1971, for instance, two former test pilots spotted and brought home a gleaming fragment of what turned out to be primordial lunar crust. That sample, nicknamed the Genesis Rock, helped geologists to understand how the Moon solidified from a molten magma ocean more than four billion years ago.
In the 2000s and 2010s, NASA trained astronauts to observe Earth from the International Space Station. Now, through visits to places such as asteroid craters and volcanic terrain, astronauts experience what it will be like on the Moon. “That way they know, when you get to the surface of the Moon — if things are not quite the way you had them in your mind, that’s OK,” says Cynthia Evans, a geologist at JSC who leads astronaut geology training.
The harsh light at the Moon’s south pole means that astronauts must prepare to work in a strangely illuminated landscape.Credit: NASA/Josh Valcarcel
Artemis III will visit a part of the Moon that has never been explored by astronauts, the lunar south pole. Because of the region’s high latitude, the illumination will be harsh and at a steep angle relative to the surface as the Sun circles the horizon. The contrast between brightly lit regions and deep shadows will make it difficult for astronauts to work in the environment.
Moon cows
Ground zero for the recent exercise in extravehicular activities (EVAs) was the San Francisco volcanic field north of Flagstaff, Arizona, where NASA and the US Geological Survey (USGS) trained Apollo astronauts in the 1960s. This month’s test, known as JETT5 for Joint EVA and Human Surface Mobility Test Team, took place on private land near a cinder cone known as SP Crater. (SP stands for ‘shit pot’, because the crater and its associated lava flow look as if someone tipped over a chamber pot and the contents flowed out onto the landscape.)
A satellite view of SP Crater in Arizona shows the volcanic crater and lava flow that serve as a simulated Moon landscape for astronauts in training.Credit: NASA/GSFC/METI/ERSDAC/JAROS, and US/Japan ASTER Science Team
Last year, USGS geologists mapped the test area and handed those maps to the researchers who gathered at JSC in a ‘science back room’ during the training exercise. The researchers drew up four simulated moonwalks, each of which ventured from a landing site to explore lava flows, gorges and other geology in the area. “This is very relevant to exactly what we’ll be doing for Artemis,” says Lauren Edgar, a geologist at the USGS in Flagstaff who is co-leader of the JETT5 science team.
During the third of the four moonwalks this month, Rubins and Douglas climbed into spacesuits that mimic what the Artemis team might wear on the Moon. They ‘disembarked’ from their ‘lander’ by walking through a set of orange poles strung with tape — and they were suddenly on the lunar surface, albeit one riddled with ant hills and cow dung.
Rubins and Douglas took photographs and began collecting rocks, radioing their observations back to mission control. They were so efficient at working through their carefully scripted checklists that they were soon running ten minutes ahead.
Some 1,600 kilometres away in Houston, their speed caught the attention of Brett Denevi, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who was serving as leader of the science back room for the evening.
Planetary geologist Brett Denevi consults with other researchers about what NASA astronauts should do during their simulated moonwalk.Credit: Michael Starghill Jr for Nature
Looking for ideas, Denevi asked the science scrum — the informal name for the team members sitting around a map-strewn table. Among them were four scientists, each of whom represented one of JETT5’s main science goals: the study of the area’s surface processes; age relationships between its rocks; its volcanic history; and whether there could be volatile elements frozen in the soil in this simulacrum of the Moon’s south pole. The scrum decided to ask whether the astronauts could collect a drive tube of eroded sediments.
Drive tubes are metal cylinders that allow geologists to collect core samples of soft sediments. During the Apollo era of lunar exploration from 1969 to 1972, NASA astronauts gathered tubes of lunar soil that revealed how cosmic rays pummel the Moon’s surface. Now, Denevi and her team wanted a sample of sediments that had eroded off a nearby rock outcrop. It was a big ask that would require the astronauts to divert from other tasks they had planned.
Each decision during the test had to be justified in real time and carefully documented. “We can’t just say we want that rock,” said José Hurtado, a geologist at the University of Texas El Paso who was Denevi’s deputy for the evening. “We have to elucidate why we want that specific rock and why it ties back to our priorities.”
Denevi walked over to a man wearing a communications headset and passed him a note. “We want to do a single drive tube,” she told him. “Here are the coordinates.”
The scientists’ request was relayed to mission control, which agreed; flight controllers then told the astronauts to go ahead and collect the requested sample. The science back room clocked that as a big win for the evening and erupted in cheers. “We did that!” said one of the scientists at the map table, pumping her arm in triumph. Soon, a series of clinking sounds filled the mission audio feed as Rubins hammered the drive tube into the ground.
Locating astronauts in real time on the lunar surface is one of the challenges that NASA is working to overcome.Credit: Michael Starghill Jr for Nature
Not everything went smoothly during the night-time EVA. The flight-operations team deliberately built in some challenges, including dropping video communications with the astronauts any time they travelled too far from the lander. An artificial, 20-minute delay on downloading imagery meant that the science team often couldn’t see real-time photos of the rocks the astronauts were picking up.
At one point, Rubins, who is a microbiologist, joked about collecting a piece of cow manure and putting it in a geological sample bag, given that it is ever-present on the Arizona ranch land.
The science back room hummed with activity on multiple audio loops and virtual chats. In addition to the scrum, another group of researchers set up at a neighbouring table to analyse images from the moonwalk, while two other scientists kept track of where the astronauts were.
Real-time videos from the ‘moonwalking’ astronauts in Arizona appear on display screens at NASA’s Johnson Space Flight Center in Houston, Texas. Scientists at the centre discuss what the astronauts should do during the training.Credit: Michael Starghill Jr for Nature
Night light
To mimic the lighting conditions at the lunar south pole, JETT5 organizers built a ‘Sun cart’ — essentially a giant spotlight wheeled onto the landscape. To Rubins and Douglas, the light looked like the distant Sun hovering just above the horizon.
The astronauts carefully navigated their way across the dim landscape, relying on a few personal lights to aid their work. Rubins in particular was thrilled to have a handheld light that she could direct where she wanted, in addition to the helmet-mounted lights that pointed only in the direction in which she was looking. “I’m going to call a light that illuminates the area near my feet totally necessary,” she told mission control — feedback that could help astronauts when they reach the Moon.
The point of JETT5 was to develop tools and procedures that will work for Artemis III astronauts on the lunar surface. But many of NASA’s challenges are much greater than working out which rocks to pick up. The Artemis programme has less funding than Apollo did — that programme and its precursors spent more than $300 billion in today’s dollars between 1960 and 1973 — and the planned cadence of Artemis missions is accordingly slower.
Artemis I, an uncrewed test of the heavy-lift rocket and crew capsule to be used for astronauts, was a 25-day space flight that orbited the Moon in late 2022. Artemis II, which will send four astronauts around the Moon without landing, is scheduled for no earlier than September 2025 and the Artemis III landing would be no sooner than September 2026. Artemis IV, another crewed mission to the surface, is pencilled in for 2028. Meanwhile, China has announced its own plans to send humans to the Moon by 2030.
Lift off! Artemis Moon rocket launch kicks off new era of human exploration
NASA has been collaborating with other space agencies on its Artemis plans. Rubins, for instance, has done extra field geology training with the European Space Agency, including at an impact crater in Germany.
“You really want to get your astronauts best acquainted with what they will come across in space in an environment on Earth that you can control and they can learn from,” says Samuel Payler, who helps to lead astronaut science training at the European Astronaut Centre in Cologne, Germany.
At the end of the evening’s moonwalk, Denevi and her team got a surprise of their own. “I forgot to tell you something super-important,” Rubins told mission control as she and Douglas were wrapping up for the night. “I found a really cool rock and I didn’t tell you about it!”
The mystery rock piqued the interest of the science back room. Rubins said it was about the size of a softball, but gave no further clues. The scientists then had to work out how to account for it in their planning, including how much it might consume of the allotted weight of rocks they were able to bring back from the ‘Moon’ during the exercise.
Mock spacesuits and a tool cart mimic the equipment that Artemis astronauts might use on the surface of the Moon.Credit: NASA/Josh Valcarcel
The next night, during the final stage of JETT5, the astronauts pulled off their longest simulated moonwalk yet, at nearly four hours. They had collected about 38 kilograms of rocks and soil, and met their main goals. As the astronauts stowed their Moon tools in Arizona, the science back room in Texas suddenly got a lot more crowded as the flight operations team joined the room for a debriefing session.
Flight controllers described how JETT5 went from their perspective, and the science back room was relieved to hear that the process worked well. “Thank you for allowing us to advocate for science — I think it was powerful to see that happen,” Cherie Achilles, a mineralogist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and co-leader of the science team, told the room.
Soon, the scientists were planning for a more extensive debriefing the next day. After that, there would be spreadsheets to finish, documents to finalize and papers to write up.
NASA isn’t planning another big exercise like JETT5 any time soon, but there will be smaller efforts to test specific tools for lunar exploration. If NASA is going to make its Artemis dreams come true, there’s a lot of work to be done.
This week, space and planetary scientists are meeting at the Goddard Space Flight Center in Greenbelt, Maryland, to scope out a new flagship NASA mission — the Uranus Orbiter and Probe. Still on the drawing board, the project would entail sending a spacecraft to orbit Uranus and drop a probe into the planet’s atmosphere. The spacecraft, which could be built and launched within a decade, would investigate the nature of Uranus, including its unusual tilt and magnetic field. It would also search the planet’s moons for signs of hidden oceans and other potentially habitable environments.
Such a mission would be groundbreaking — the first to orbit an ‘ice giant’ planet. Thought to be made mostly of ices, or perhaps dominated by rocks, ice giants Uranus and Neptune have more exotic chemistry than do Jupiter and Saturn, which as ‘gas giants’ consist mainly of hydrogen and helium gas1,2. Ice giants are also the most common type of exoplanet in the Milky Way3. With characteristics that lie between those of gas giants and of Earth and other terrestrial planets, it’s crucial to learn how such systems formed and evolved.
That’s why the Uranus Orbiter and Probe was given priority status in the 2022 US Planetary Science and Astrobiology Decadal Survey. And NASA is set to lead it. At the Goddard workshop, scientists will scope out the mission and consider its design, technologies and costs.
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The mission has been under discussion for some time, and it will be exciting to see it begin to take shape. But, to make sure it is successful and happens as quickly and cost-effectively as possible, we would like to see others involved in its design, too. As a first step, we call for the European Space Agency (ESA) to join the project by, for example, building the entry probe — a possibility that was foreseen in the decadal report and has been assessed by ESA but has not yet been agreed.
The window for such an agreement is closing fast. There is a strong scientific benefit to reaching Uranus near 2050, when its position in its orbit will mean that sunlight will fully illuminate all parts of the spinning planet and its orbiting moons. Given a typical 10-year development time for a flagship mission, paired with long flight times to Uranus (12–15 years, depending on launch date and vehicle), this would require work on the Uranus Orbiter and Probe to commence in the next few years.
NASA has stated that it hopes to start releasing funding for the mission in 2026 or 2027. By contrast, ESA’s current budgetary programme does not include any substantial contribution to a NASA flagship mission in the coming years. This is a troubling, and in our view short-sighted, stance with long-lasting repercussions. Here’s why.
Distant worlds
The scientific drivers for a Uranus mission are compelling. Dedicated missions to Jupiter and Saturn, including Galileo, Juno and Cassini–Huygens, have made major discoveries, including subsurface oceans on icy moons that might have the potential to harbour life4. Yet Uranus and Neptune have so far been snapped only briefly, as the Voyager 2 spacecraft sped past them in the 1980s.
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Little is known about how these ice giants formed. Was Uranus a failed gas giant that formed too late to accrete hydrogen and helium gas before the Sun’s gaseous nebula dissipated? Or was it created through a different process, with more in common with Earth’s genesis? Did Uranus form closer to Jupiter and then move away, ejecting comets into the inner Solar System that ultimately delivered water to Earth, as theories suggest? Finding answers will teach us about the origin of the Solar System as well as systems around distant stars.
Measuring the composition of Uranus’s atmosphere would constrain the conditions under which the planet formed and show how these have changed with time5. The puzzlingly large tilt of Uranus’s axis of rotation (almost parallel to the plane of the Solar System) could be examined, along with the planet’s internal structure and magnetic field1,2,6,7. The mission would unravel the origin of Uranus’s extensive dusty rings and moons8. Repeated fly-bys could check whether Uranus’s satellites have subsurface oceans, as those of Jupiter and Saturn do.
Shared goals
With so much fundamental knowledge at stake, we argue for broader involvement of the planetary-science community in planning the Uranus Orbiter and Probe. The 2022 decadal survey emphasized the opportunity for international partnerships for this project. It noted that in 2021, a committee of senior scientists advising ESA on its long-term plan (Voyage 2050) recommended that ESA pursue a ‘medium class’ contribution to an ice-giant orbiter mission led by an international partner. ESA has evaluated the possibility of providing the entry probe, which it estimates could be done within the medium-sized-mission budget of around €500 million (US$537 million). But no commitment has yet been made.
A partnership between NASA and ESA to explore the Uranian system would offer advantages for both space agencies. For NASA, it would reduce costs and facilitate the provision of instruments. For ESA, it would offer European scientists the opportunity to participate in a groundbreaking, flagship-class mission at a relatively low cost. It would also foster collaboration between the two continents in this long mission, echoing the success of Cassini–Huygens — the most scientifically prolific robotic endeavour so far in the exploration of the outer Solar System.
Curious blocks of ice and rock on Uranus’s moon Miranda were spied by Voyager 2.Credit: NASA/JPL-Caltech
Furthermore, a lack of substantial European involvement in a perhaps once-in-a-lifetime ice-giant flagship mission would undermine the large community of scientists, engineers and technicians engaged in space exploration across Europe who have strong interest in planets and the search for extraterrestrial life. It could also affect the mission itself, because the need for NASA to fund both the orbiter and the probe could delay the mission’s start and arrival, which would diminish its scientific return.
Next steps
Given the long timelines involved in constructing the mission and its long travel time, we urge NASA to swiftly initiate the study of the Uranus Orbiter and Probe mission. This would generate excitement to foster international cooperation with ESA and with national space agencies that have well-established collaborations with NASA, such as JAXA in Japan and the United Arab Emirates Space Agency.
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We also call on ESA to prioritize funding to support this strategic collaboration, building on past successes through Cassini–Huygens and at a fraction of the cost of a European-led ice-giant flagship mission. Contributing an entry probe to the project would accelerate the mission’s timeline, add international momentum and reduce the costs for NASA. We would all get these crucial results sooner rather than later, and be able to visit the system when it is fully illuminated rather than in partial darkness.
In the absence of such a commitment from ESA, a promising alternative would be to establish a consortium of individual European countries to be responsible for constructing the probe. Financial-resource constraints would probably limit the instrumentation, and perhaps the depth such a probe could penetrate, but with careful design, the probe could still return crucial data.
Tension between ambitious Solar System exploration goals and budgetary pressures is likely to remain a reality for Europe and the United States in the short term. Increasing international collaboration could be the key that allows NASA and ESA to achieve their plans and maximize scientific return in an era of constrained budgets.
It would also pave the way for other breakthroughs. ESA’s programme includes support for a flagship life-detection mission to the surface of Saturn’s moon Enceladus in the early 2050s, and a similar mission was the second highest priority flagship mission identified for NASA in the 2022 decadal survey report. A NASA–ESA partnership for Uranus now would set the stage for future joint missions.
The planet 55 Cancri e (artist’s impression) orbits very close to its star.Credit: Mark Garlick/Science Photo Library
Astronomers say that they have used the James Webb Space Telescope (JWST) to detect for the first time an atmosphere surrounding a rocky planet outside the Solar System1. Although this planet cannot support life as we know it, in part because it is probably covered by a magma ocean, scientists might learn something from it about the early history of Earth — which is also a rocky planet and was once molten.
Finding a gaseous envelope around an Earth-like planet is a big milestone in exoplanet research, says Sara Seager, a planetary scientist at the Massachusetts Institute of Technology in Cambridge who was not involved with the research. Earth’s thin atmosphere is crucial for sustaining life, and being able to spot atmospheres on similar terrestrial planets is an important step in the search for life beyond the Solar System.
The planet investigated by JWST, called 55 Cancri e, orbits a Sun-like star 12.6 parsecs away and is considered a super-Earth, a terrestrial planet a little bigger than Earth — in this case, with about twice Earth’s radius and more than eight times as heavy. According to a paper published today in Nature1, its atmosphere is probably rich in carbon dioxide or carbon monoxide and has a thickness that is “up to a few per cent” of the planet’s radius.
A mysterious planet
Another reason that 55 Cancri e is uninhabitable is that it is very close to its star — around one sixty-fifth of the distance from Earth to the Sun. And yet, “it’s perhaps the most studied rocky planet”, says Aaron Bello-Arufe, an astrophysicist at the Jet Propulsion Laboratory (JPL) in Pasadena, California, and a co-author of the paper. Its host star is bright in our night sky, and because it is large for a rocky planet, it’s easier to study than other planets outside the Solar System. “Every telescope or instrument that you can think of in astronomy has pointed to this planet at some point,” Bello-Arufe says.
55 Cancri e was so well studied that after JWST launched in December 2021, engineers pointed the observatory’s infrared spectrometers towards it for testing. These instruments can detect the chemical fingerprints of gases swirling around planets as they absorb infrared wavelengths from starlight. Bello-Arufe and his colleagues then decided to dig deeper to confirm whether the planet had an atmosphere.
Before the latest observations, astronomers had changed their minds about 55 Cancri e myriad times. The planet was discovered in 20042. At first, researchers thought it was probably the core of a gas giant similar to Jupiter. But in 2011, the Spitzer Space Telescope observed the planet as it passed in front of its star3, and researchers found that 55 Cancri e is in fact a lot smaller and denser than a gas giant, making it a rocky super-Earth.
55 Cancri e is a little bigger than Earth, but much smaller than the Solar System’s giant planets, such as Neptune.Credit: NASA, ESA, CSA, Dani Player (STScI)
Some years later, researchers noticed that 55 Cancri e was cooler than it should have been for a planet so close to its star, indicating that it probably has an atmosphere4. One hypothesis was that the planet is a ‘water world’ enveloped by supercritical water molecules; another was that it is surrounded by an expansive, primordial atmosphere composed mainly of hydrogen and helium5. But these ideas were eventually disproved.
A planet so close to its star would be bombarded by stellar winds and have a hard time holding on to volatile molecules in its atmosphere, says Renyu Hu, a planetary scientist at JPL and a co-author of the latest study. Two possibilities remained, he says. The first was that the planet is completely dry, with an ultrathin atmosphere of vaporized rock. The second was that it has a thick atmosphere composed of heavier, volatile molecules that do not bleed away easily.
A clearer picture
The latest data indicate that 55 Cancri e’s atmosphere contains carbon-based gases, pointing to option two. The team collected bona fide evidence of an atmosphere, Seager says, but more observations are needed to determine its full composition, the relative quantities of gases present and its precise thickness.
Laura Schaefer, a planetary geologist at Stanford University in California, is interested in learning how 55 Cancri e’s atmosphere interacts with materials beneath the planet’s surface. It’s still possible that the atmosphere is being eroded by stellar winds, the study’s authors say, but the gases could be getting replenished by the melting and outgassing of rocks in the magma ocean.
“Earth probably went through at least one magma-ocean stage, maybe several,” Schaefer says. “Having actual present-day examples of magma oceans can help us understand the early history of our Solar System.”
