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Yahoo
3 days ago
- Science
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Why is the moon's far side so weird? China's lunar sample-return mission may have figured it out
When you buy through links on our articles, Future and its syndication partners may earn a commission. The origin of the strange differences between the near and far sides of the moon are a step closer to being solved, thanks to new findings from China's Chang'e 6 mission that returned samples from the South Pole-Aitken (SPA) basin. The near side of the moon is familiar to us as the only side that we can see from Earth. Dark regions called maria are vast lava plains filling lowland impact basins, and give us the pattern of the "man in the moon." Yet the far side of the moon, which can only be seen by orbiting spacecraft, has barely any maria and is covered by craggy, cratered and ancient highlands. That's not the only difference between the two hemispheres; the thickness of the moon's crust is thinner on the near side, volcanic activity appears to have occurred at different points in time, and the mantle beneath the far side seems heavily depleted in certain elements compared to the near side. However, while we have many samples from the lunar near side, particularly those brought back to Earth by the Apollo missions, the Soviet Luna missions and China's own Chang'e 5, we had nothing from the far side with which to test theories. Then, in June 2024, China's Chang'e 6 mission landed in the SPA basin and brought back samples totaling 1,935.3 grams (68.27 ounces). The SPA basin is the largest impact site on the moon, spanning 2,500 kilometers (1,600 miles) and extends from the lunar south pole and onto the far side of the moon. It's also the oldest known impact feature on the moon, with an age of 4.25 billion years. What impact — pardon the pun — could the sheer violence of the SPA basin's formation have had on lunar geology and the thermal evolution of the moon's interior? Could it have caused the dichotomy between the moon's two hemispheres? Chang'e 6's samples are the first from the lunar far side, and have offered a unique opportunity to test models that could potentially explain the difference between the moon's two hemispheres. Consequently, following analysis of the samples, researchers led by a team from the Chinese Academy of Sciences have announced four major discoveries. The first is that the samples contain volcanic rocks called basalts that date to prolonged volcanic outbursts on the lunar far side in two distinct phases, one around 4.2 billion years ago and another 2.8 billion years ago. "We propose that the 4.2-billion-year-old basalt was associated with the formation of the SPA basin because it is a high-aluminum basalt, requiring the incorporation of crustal plagioclase into its source," Wei Yang, a professor at the Institute of Geology and Geophysics at the Chinese Academy of Sciences, told in an email interview. Meanwhile, "the 2.8-billion-year-old basalts originated from the deep mantle, the product of the early stage crystallization of the lunar magma ocean." The evolution of this lunar magma ocean that formed the moon's mantle is central to the next discovery, which is that geochemical analysis of the basalt samples points to a source in the lunar mantle deep below ground that is heavily depleted in particular elements such as thorium. It is unknown whether this depleted mantle is found only beneath the SPA basin, or whether it is more extensive across the moon. "To be honest, we don't know," said Yang. One possibility is that the moon has had this depleted mantle since birth, in which case both the near and far sides should share this composition. The other possibility is that it was produced after the lunar magma ocean formed and began to crystallize. "Personally, I am more inclined to believe the latter, given that such a massive impact has the potential to affect the mantle down to a depth of 250 kilometers [155 miles]," said Yang. "If it is only present in the SPA basin, then it must have formed as a result of the SPA impact. To figure this out, we need to collect more samples from the moon's far side, particularly from areas outside the SPA." The third discovery is of something we wouldn't expect to find on the moon: water. However, we are talking parts-per-million here — the Apollo samples were considered "bone dry," and the far side mantle seems to be even drier than that. "The water content of this mantle is lower than those of the mantle sources of all the basalts from the near side," said Yang. The final discovery relates to the moon's magnetic field. Earth's natural satellite currently doesn't have a global magnetic field, and traces of magnetism remain only in a handful of anomalous patches called lunar swirls. However, in the distant past it did have a global magnetic field. The Chang'e 6 samples retain a record of it, and show that the magnetic field, after decaying for a time, rebounded in strength about 2.8 billion years ago. This indicates that the moon's internal dynamo fluctuated, possibly episodically, rather than just experiencing a slow but gradual decline. Related Stories: — Why is the far side of the moon so weird? Scientists may have solved a lunar mystery — The far side of the moon was once a vast magma ocean, Chinese lunar lander confirms — China returns samples from the moon's far side in historic 1st (video) The timing coincides with the second phase of volcanism on the far-side. "The magnetic field rebounded 2.8 billion years ago, which suggests that the interior of the moon still contained a lot of energy," said Yang. "Perhaps convection and the upward flow of hot material existed in the lunar mantle at that time." Not only could this upward flow have triggered volcanic eruptions, it could have been enough to vaporize much of the water in the mantle, drying it out. If the creation of the SPA basin is the cause of much of this, then it has repercussions that go far beyond the moon. Other giant impact features are seen on other bodies, particularly on Mercury and Mars. We may have underestimated the role that these giant impacts played on the evolution of the planets' interiors. The Chang'e 6 results were presented in four papers (1, 2, 3, 4) that were published recently in the journal Nature.
India Today
10-07-2025
- Science
- India Today
Mega crash on the Moon released energy equal to 1,000,000,000,000 atomic bombs
China's ambitious Chang'e-6 mission has delivered new insights into the Moon's geological past, particularly the differences between its near and far on May 3, 2024 the mission returned with 1,935.3 grams of lunar material from the South Pole–Aitken Basin (SPA) on the Moon's far side, arriving back on Earth on 25 June samples have enabled scientists to explore one of planetary science's long-standing mysteries regarding the Moon's topographical and compositional The SPA, the largest and oldest impact structure on the Moon, was formed approximately 4.25 billion years ago by a massive impact. This event is thought to have released energy equivalent to that of a trillion atomic bombs. The Moon samples arrived on Earth on June 25, 2024. (Photo: CNSA) Until recently, the impact's effects on lunar geology and thermal evolution remained unsolved, but recent studies have begun to unravel these conducted over the past year by teams from CAS institutions, including the Institute of Geology and Geophysics (IGG) and the National Astronomical Observatories (NAOC), has led to four significant findings were published in the journal Nature, marking a major step forward in understanding the lunar landscape. According to Prof. WU Fuyuan, "the geological consequences of the impact that formed the SPA are, for the first time, revealed collectively in these four Nature papers."One key discovery is the evidence of prolonged volcanic activity on the Moon's far side. The analysis identified two distinct volcanic phases occurring 4.2 billion and 2.8 billion years persistence of volcanic activity for at least 1.4 billion years is far longer than previously a fluctuating magnetic field was observed. Measurements revealed a resurgence in the Moon's magnetic field around 2.8 billion years ago, indicating that the lunar dynamo responsible for generating magnetic fields was more active than previously thought, experiencing episodes of fluctuation rather than a steady samples also highlight an asymmetric water distribution between the Moon's near and far far side's mantle contains significantly less water, suggesting an uneven distribution of volatile elements within the lunar interior, shedding light on the Moon's compositional diversity. Finally, geochemical analyses of the basalt samples unveiled a mantle source described as "ultra-depleted," pointing to a primordial depleted mantle or massive melt extraction due to large impacts. This insight points to the role of major impacts in shaping the Moon's findings not only illuminate the evolution of the Moon's far side but also shows the transformative impact of the Chang'e-6 mission, offering a critical reference point for studying early Solar System impacts.- EndsMust Watch
Yahoo
13-05-2025
- Science
- Yahoo
'Marsquakes' reveal clues about a hidden body of water on Mars
When you buy through links on our articles, Future and its syndication partners may earn a commission. Scientists have found seismic clues that suggest liquid water may be hiding beneath Mars' surface. By listening to the echoes of "marsquakes" — seismic waves rippling through Mars' crust — researchers uncovered signs of water lingering at the base of the planet's upper crust, which sits between 3.4 and 5 miles (5.4 and 8 kilometers) below the surface. "Within our solar system, Mars has consistently been at the forefront of the search for extraterrestrial life," said Weijia Sun, a professor at the Institute of Geology and Geophysics, Chinese Academy of Sciences and one of the study's authors, to Space. "The presence of liquid water is regarded as one of the most critical factors in this endeavor." Liquid water was thought to once flow freely across Mars during the planet's Noachian and Hesperian periods — an era stretching from the planet's formation up to about 3 billion years ago. However, as Mars entered the Amazonian period, its climate dramatically shifted. Surface water disappeared, leaving behind the cold, dry landscape we see today. "While the presence of flowing water on Mars is now indisputable, the volume and mechanisms of its disappearance remain subjects of active debate," said Sun. One theory suggests Mars lost its water to space as solar wind stripped it from the atmosphere — a process supported by ratios of isotopes on the Red Planet, or distinct species of chemical elements, seen today. Another proposes that the water didn't vanish, but rather sank into the crust. This would suggest pockets of water in deep underground aquifers. While some models predict liquid water could survive in the middle crust, its extent remains uncertain due to a lack of detailed structural data from those depths. NASA and other space agencies have sent rovers and orbiters equipped with ground-penetrating radar to explore beneath Mars' surface — but these tools can only see a few miles deep. That's because electromagnetic signals quickly fade as you go deeper into the crust. But Sun and his team took a different approach. Instead of radar, they tapped into data of seismic waves generated by two massive meteorite impacts (S1000a and S1094b) and the largest recorded marsquake (S1222a). "While previous computational studies have suggested the potential presence of liquid water on Mars, these predictions lacked observational support that seismology offers," he said. By analyzing how these waves traveled through the crust, they were able to map its fine structure — and search for anomalies that might hint at liquid water. "We used a technique called 'receiver functions,' which represent the signatures of seismic waves as they reflect and reverberate between crustal layers, analogous to echoes mapping a cave," Hrvoje Tkalčić, a professor at The Australian National University and co-author of the study, told "These signatures enable the precise identification of the thicknesses of layers and the depth to the boundaries where rock properties change." "Unlike traditional receiver function techniques, we introduce the concept of true-amplitude imaging, a method adapted from the oil exploration field, which significantly improves resolution and allows the detection of much smaller structures," Sun said. "The true-amplitude receiver function acts as a magnifying glass, enhancing the clarity of subsurface features.' The team's analysis revealed an unusual zone deep underground at about 3 to 5 miles (5 to 8 kilometers) where seismic waves slowed down. Initially, this was thought to be the result of a fractured sedimentary layer of rock, where reduced stiffness and increased compliance make the rock less able to transmit a wave's energy. However, based on its position within the crust, it was unlikely this layer was made up of sediments. "In general, seismic waves propagate significantly faster through dry rock than through water-saturated rock," said Sun. Instead, the team suggests this "low velocity" layer could actually be filled with liquid water because rocks in this area, called altered basalts, have high porosity, which might allow them to hold water. "Through a comprehensive analysis, we inferred that the low-velocity layer could be attributed to the presence of liquid water, where temperatures exceed the freezing point within the specified depth range," Sun said. Based on their data, they estimated the existence of between 569 and 853 yards (520–780 meters) of Global Equivalent Layer (GEL) — a metric used to quantify the volume of water when distributed uniformly across the entire surface of a planet or moon. This number roughly coincides with the between 776 and 1,006 (710 and 920 meter) GEL, that cannot be accounted for with Mars' present-day water inventory. Related Stories: — Mars orbiter snaps 1st image of Curiosity rover driving on the Red Planet (photo) — NASA's Curiosity Mars rover discovers evidence of ripples from an ancient Red Planet lake (images) — Perseverance Mars rover finds 'one-of-a-kind treasure' on Red Planet's Silver Mountain "The presence of subsurface water on Mars holds significant implications for future human missions and the potential for extraterrestrial life," said Tkalčić. "However, drilling or extracting water from deep underground would necessitate advanced technology and substantial energy resources." While this study provides critical insights into the Martian water cycle and the evolution of its environment, the researchers emphasize that their estimate is based solely on data gathered from a local profile beneath the InSight lander, located in the Elysium Planitia region, about 4.5 degrees north of the Martian equator. This could mean the findings are specific to this particular area and may not fully represent the planet's entire surface. "This limitation can be addressed by future missions equipped with seismometers on Mars," concluded Tkalčić. The study was published on April 25 in the journal National Science Review.
The Star
08-05-2025
- Science
- The Star
China fires up powerful radar to search for lunar ice that can make or break moon race
Water ice is likely to exist at the moon's south pole, but it would be fragmented, scattered and buried deep beneath the surface, posing significant challenges for detection and extraction, according to a new study by Chinese researchers. Using powerful Earth-based instruments, including the world's largest radio telescope and one of the most advanced radar systems, the team estimated that ice made up no more than 6 per cent of the material within the top 10 metres (33 feet) of lunar soil in the region. The ice was thought to exist as metre-sized chunks buried 5-7 metres underground in the moon's most promising 'cold traps', known as permanently shadowed regions. Smaller, isolated patches might also lie near the surface, the team wrote in the latest issue of the Chinese journal, Science Bulletin. Do you have questions about the biggest topics and trends from around the world? Get the answers with SCMP Knowledge, our new platform of curated content with explainers, FAQs, analyses and infographics brought to you by our award-winning team. The findings, the researchers wrote, could help in the selection of landing sites for future lunar missions and inform the design of the proposed China-led research base on the moon. Hu Sen, a planetary geochemist at the Institute of Geology and Geophysics in Beijing, called the work 'impressive'. He said that using China's newly built incoherent scatter radar in Sanya (SYISR) alongside the FAST telescope to search for water ice was a 'really creative approach'. While Hu was not involved in the research, he noted that the results aligned with previous impact experiment findings and added new evidence that water ice existed on the moon. 'The study also opened a new pathway to investigate water abundances on the moon,' he said. So far, no liquid water has been found on the moon. 'What we do know is that some water is bound within the lunar soil as 'structural water', and some is preserved as ice in cold traps inside permanently shadowed regions,' Hu said on Wednesday. But the moon's surface is an unforgiving environment, marked by a high vacuum, strong radiation and extreme temperature swings. 'Before anyone can actually make use of that water, we need to understand where it comes from, how it's distributed and how it's stored,' he said. One of China's key science goals for the coming Chang'e-7 mission, set to launch next year, is to determine the amount, origin and physical state of water ice at the moon's south pole. The mission is expected to significantly advance understanding of lunar water, he said. Still, the topic remains contentious. There is no conclusive proof that water ice exists in usable quantities on the moon. Alfred McEwen, a planetary geologist at Arizona State University, said he believed there was 'extremely little' water on the moon. 'All the talk about what a valuable resource this is seems like baloney to me,' he said on Tuesday. However, planetary geologist Clive Neal at the University of Notre Dame in the United States suggested that the actual amount of water ice at the lunar south pole could be higher than what this study detected. Radar only covered limited areas, mostly crater slopes, he said. 'It is expected that the water ice would be in the bottom of the craters,' he said, adding that the areas visible to the radar were also affected by Earthshine, which could cause any surface ice to evaporate. In recent years, researchers have paired high-powered, large-aperture incoherent scatter radars – typically used to study the ionosphere – with large radio telescopes to capture imagery of the moon's surface, according to the paper's lead author Li Mingyuan, of the Institute of Geology and Geophysics. For instance, the Arecibo planetary radar system in Puerto Rico and the Green Bank Telescope in West Virginia have jointly produced lunar polar images with resolution ranging from 20 to 150 metres, according to Li. Building on that approach, Li and his team used the Sanya incoherent scatter radar and the Five-hundred-metre Aperture Spherical radio Telescope (FAST) to carry out a ground-based radar imaging experiment focused on the moon's south pole. The SYISR radar, with its wide beam, was used to track the moon's centre of mass and scan its entire near side. Meanwhile, the narrower beam of the FAST telescope focused specifically on the south pole region to receive radar echoes, he said. Thanks to FAST's high sensitivity, the team could produce radar images covering latitudes of 84 and 90 degrees south, at a resolution of about 500 metres by 1.2km. Li noted that their analysis assumed the radar signals were caused by water ice. However, one of the key parameters – the circular polarisation ratio, which measures how much of the radar signal bounces back in a rotated form – can also be elevated by surface roughness or buried rocks, making it difficult to distinguish ice from non-ice terrain. The study offered a preliminary estimate, Li said, and further work required integrating data from multiple instruments or radar frequencies to improve the accuracy of identifying water ice. More from South China Morning Post: For the latest news from the South China Morning Post download our mobile app. Copyright 2025.
Yahoo
09-04-2025
- Science
- Yahoo
China's Chang'e 6 lunar samples suggest our moon is debris from an ancient Earth impact
When you buy through links on our articles, Future and its syndication partners may earn a commission. There's less water in the mantle beneath the farside of the moon than in the mantle on the nearside, according to studies of the precious lunar samples brought back to Earth by China's Chang'e 6 mission. Furthermore, the findings bolster the theory that the moon formed when a giant, Mars-size protoplanet slammed into the young Earth about 4.5 billion years ago and sent a cascade of debris into orbit that coalesced into the powdery gray orb we see today. "We believe the new result is in line with the giant impact hypothesis of the moon," HU Sen, a professor at the Institute of Geology and Geophysics at the Chinese Academy of Sciences, told Chang'e 6 arrived at the South Pole–Aitken (SPA) basin, located on the farside of the moon, in June 2024. The lander's robotic drill and scoop collected 4.27 lbs (1.935 kilograms) of basaltic regolith from the SPA basin before returning it to Earth. Chang'e 6's treasure trove of lunar material is the first sample to be collected from the moon's farside. As such, it has some questions to answer. Among them is whether its water content is compatible with the giant impact theory of the moon's formation. Modeling of the giant impact scenario suggests the mantle on the farside of the moon should have less water than the nearside does. One line of evidence for this comes from the relative abundances of thorium on the lunar surface. Magma is formed from melt within the mantle, and the areas of the mantle that produce such melt are referred to as the "mantle source." When magma is formed in the mantle source, thorium, like water, remains in the melt rather than producing crystalline minerals. Therefore, the abundance of thorium on the surface can act as a proxy for water. The nearside, covered in ancient deep impacts and volcanic flows, has regions that are rich in thorium, as we would expect. Few areas on the farside, with its dearth of volcanism, have a high abundance of thorium. However, the SPA basin is an exception: as a giant impact basin, its floor is flooded by now-solid lava that welled up through the wound in the moon's surface from the mantle below, like blood oozing from a cut. As one of the few impact basins on the farside, the SPA basin is one of the few farside locations with thorium on the surface, where the impact that formed the basin dug deep enough into the mantle to bring the melt to the surface. So, the logic goes, if the SPA basin has less thorium, then perhaps it means the mantle source has less water too. Analysis of the basaltic (volcanic) rock brought back from the SPA basin by Chang'e 6 yields a mantle source water content of between just 1 and 1.5 μg.g⁻¹ (micrograms — millionths of a gram — per gram of sample). "The modeling results suggest that the lunar mantle would have a maximum water content of less than 10 μg.g⁻¹ This estimate is substantially lower than the average water content in the nearside mantle, based upon the study of Apollo-mission samples that suggest a value of up to 200 μg.g⁻¹, depending upon the location on the nearside. "If the lunar interior on the farside is drier than the nearside, it means the water in the lunar mantle may exhibit dichotomic distribution," said Hu. This difference, or dichotomy, between the water abundance in the mantle on the farside compared to the nearside of the moon is just one more thing to add to the list of differences between the two hemispheres. Topology, volcanism, surface ages, rock types and the aforementioned thorium difference are just some of the differences that any hypothesis attempting to model the formation and subsequent evolution of the moon have to explain. Related Stories: — The far side of the moon was once a vast magma ocean, Chinese lunar lander confirms — China returns samples from the moon's far side in historic 1st (video) — Ancient impact that formed Earth's moon was likely a one-two punch "We infer that such a dichotomic distribution of water in the moon may be the result of the massive impact event forming the SPA basin," said Hu. The SPA basin is huge, spanning 1,600 miles (2,500 kilometers ) and is one of the very largest examples of its kind in the solar system — its effects on the rest of the moon, particularly the farside, would have been enormous. "Another possibility is the water in the lunar mantle may exhibit secular distribution," said Hu. "For instance, the deeper and earlier-formed lunar mantle may have relatively lower water content than the shallower and later-formed mantle source." One thing is for sure: Despite being as dry as a bone, the moon's farside continues to be one of endless fascination. The analysis of the Chang'e 6 samples was reported on April 9 in the journal Nature.
