China's men's national volleyball team were relegated from the FIVB volleyball Nations League after a disappointing run in the league's preliminary phase, raising questions about the future of the men's national team.
Following Sunday's 3-1 defeat by Canada in the final match of the preliminary phase, China finished the annual international tournament at the bottom of 16 teams with a 2-10 win-loss record.
The relegation sends China into the FIVB Challenger Cup to be held in Qatar from July 27 to 30. They will be able to return to next season's Nations League only if they win the Challenger Cup, which is a big question mark for the team.
A bigger question mark lies ahead when China turns its focus to the Hangzhou Asian Games in September and then participating in the Paris Olympic Games qualifiers in Xi'an, Northwest China's Shaanxi Province, from September 30 to October 8.
Only the top 24 teams in the world rankings will be eligible for the Olympic qualifiers and China is out of the loop, ranking world No.25 currently.
The relegation sounds the alarm for China's volleyball team to reflect on its missteps and focus on the basics.
Wu Sheng, head coach of the national team, said in June that it would be difficult to emerge from the Olympic qualifiers. If they fail in the qualifiers, the team will have to fight for an Olympic berth through better world rankings. But volleyball fans are of the mind that only miracle could help China qualify for the Paris Olympic Games.
Fans also vented their anger toward the coach for the team's error-strewn performance in the Nations League, blasting him for substitutions, ill-timed challenge calls and his inability to adjust to instantaneous changes on the court.
Wu takes full responsibility for the team's performance but that does not paper over the widening gap between China and world heavyweights that has been laid bare in the league as the team was blown out in serving, reception, blocking, offense and setting.
Wu said after the relegation that the worst problem lies in setting.
"I'm not happy with all three setters. We don't have a consistent starting lineup," he said.
When we look up to the other end of the Nations League table, Japan sits second with a 10-2 win-loss record.
Statistics indicate that it all boils down to basics. It has been Japan's solid reception and defense that enabled it to prevail against physically stronger opponents. Miracles came from years of hard work in honing the team's basic skills.
The Belgrade Philharmonic Orchestra (BPO) held a splendid concert at the National Centre for the Performing Arts (NCPA) in Beijing on Tuesday night, celebrating its 100th anniversary.
This is the BPO's second visit to China, coming 23 years after the previous visit. The BPO's China tour was initiated by the legendary conductor Zubin Mehta, who hopes to support the orchestra's international promotion in prestigious music centers that only offer venues to the most distinguished orchestras. Mehta believes that the BPO deserves a place among the finest symphonic ensembles in the world. However, due to health issues, Mehta had to cancel his performance.
The BPO's China tour was taken over by Neeme Jarvi, a renowned conductor from Estonia. With a brilliant career spanning decades, including conducting some of the most famous orchestras and top soloists, and more than 450 recordings, Jarvi is one of the most respected conductors in the world.
"Mr Mehta could not come because of his health, so I took his place at the last minute," Jarvi told the Global Times about his China trip.
But for the experienced Jarvi, he was ready for every performance. "I have prepared for it all of my life," he told the Global Times.
Before coming to Beijing, the orchestra had performed in Xi'an, Northwest China's Shaanxi Province, where Jarvi praised China for having a large number of well-equipped concert halls, which is something that he said Estonia needs to learn from.
"With the need for a hundred people to be accommodated, without acoustics, we need to build those halls and we need to pay attention to the culture, especially for music. We should learn from China. China is doing a wonderful thing," he said.
The BPO is the most famous symphony orchestra in Serbia, and was founded in 1923. It has collaborated with many world-renowned conductors and soloists, performing music works of various styles and periods. The orchestra enjoys a high reputation on the international stage, and has been hailed as "the musical pearl of the Balkans."
On November 18, the orchestra will perform at the Shanghai Grand Theatre, as part of the Shanghai International Music Festival.
During the tour, the BPO will share the stage with soloists and violinists including Giovanni Andrea Zanon and Huang Mengla, performing works by Tchaikovsky, Verdi, Berlioz and Beethoven.
A highly anticipated exhibition titled "Civilizations of the Great Rivers" opened at the Ningbo Museum in East China's Zhejiang Province on July 6. The exhibition showcases a total of 200 cultural relics from four major museums in Italy and 13 cultural and heritage institutions in China.
It is co-hosted by the Ningbo Museum and the China Cultural Relics Exchange Center, with joint support from four prestigious museums in Italy - the Egyptian Museum, the Royal Museum, the Museum of Oriental Art in Turin, and the Giovanni Barracco Museum of Ancient Sculpture in Rome.
Italian Ambassador to China Massimo Ambrosetti and the Consul General of Italy in Shanghai Tiziana D'Angelo were invited to the opening ceremony of the exhibition.
The exhibition showcases artifacts related to the Liangzhu civilization and the Erlitou culture, providing evidence of the enduring nature of the Chinese civilization over the last 5,000 years.
The final section of the exhibition hall, dedicated to the "Silk Road," symbolically connects the rivers to the oceans to illustrate how civilizations are interlinked. This section also delves into the present-day significance of the exchange and convergence of different civilizations and the emergence of new dynamics.
This collaboration marks a new chapter in cultural exchanges and cooperation between China and Italy and promotes each country's splendid civilization and rich history.
In recent years, the city of Ningbo has achieved significant results in cooperation with its Italian sister cities, not only in the field of economic trade but also in the promotion of historical heritage, cultural and artistic research, and the exchange of expertise in the restoration of cultural relics. These achievements have become highlights of bilateral exchanges and cooperation between the two countries.
After the event, the ambassador also visited the Tianyige Museum to appreciate Ningbo's long history of book collection and culture, and to witness the ancient art of book repair and preservation.
The exhibition will run until October 8, according to media reports.
Recently, in the waters near Huangyan Dao in the South China Sea, a series of actions that clearly appear to be "premeditated" have created tension.
A vessel of the Bureau of Fisheries and Aquatic Resources of the Philippines, without China's permission, intruded into the adjacent waters of Huangyan Dao and attempted to enter its lagoon. The Philippine government vessels carrying journalists from Western countries equipped with cameras and other equipment for on-site filming also came to the waters near Huangyan Dao. The Philippine government vessels have even provided approximately 60,000 liters of diesel fuel and some groceries to the Filipino fishing boats in an attempt to encourage them to approach Huangyan Dao aggressively, thus providing fresh news material for Western journalists.
Let's take a look at how these Western journalists have reported on this largely staged story. The AFP used such a scene as a starting point: A Filipino fisherman guns the motor of his tiny wooden boat as he makes a dash for the shallow waters of Huangyan Dao, with Chinese coast guard speedboats in hot pursuit. This disjointed narrative aims to convey a strong sense of visuals and tension, attempting to depict a simple image of the "Chinese coast guard intimidating Filipino fishermen." Its headlines focused on "Filipino fisherman chased by China's coast guard" in the South China Sea, making it the most representative among the Western media present.
However, what's strange is that, compared to the efforts made by these Western media outlets and the Philippine side to stage this performance, the final products they presented are rather thin, lacking in impact and persuasiveness. Any audience with a modicum of critical thinking would find the story unconvincing. Their reports focused on depicting certain specific details, but were vague and even unwilling to mention more factual information, leading to numerous flaws and serious inaccuracies in their reporting.
The interception of Chinese coast guard ships in response to this behavior was legitimate and necessary. Additionally, the location of the "floating barrier" set up by China was at the entrance to the lagoon inside Huangyan Dao, clearly designed to safeguard sovereignty interests and not indicative of any "intimidation."
These media outlets will not mention the restraint and professionalism of the Chinese coast guard when intercepting Filipino fishing boats. Even less will they mention that just a few days ago, the PLA naval vessel Aba successfully rescued two Filipino fishermen during its cruise in the eastern maritime zone of the Nansha Islands. Those Filipino actors should not be blamed for their poor performance; the key issue lies in the fact that a large part of the "plot" is not controlled by the Filipino side or Western media. China will never act according to their script.
In the end of its report, the AFP quoted a so-called Filipino fisherman as saying, "If they ram and sink our boats, who will save us?" This was an attempt to play the sympathy card, which the AFP is known for. However, since the whole story has not been established, this ending appears to be weak and even somewhat ridiculous.
Overall, this is an unsuccessful hype by the Philippine side in collaboration with Western media. However, it has exposed a new trend in the South China Sea that should alert all parties: the strengthening of the Philippines' domestic radical forces in alliance with external powers on the South China Sea issue. They have put considerable effort into creating public opinion and intentionally engaging in a media war.
Previously, the Philippines hyped up the issue of Chinese fishermen "destroying coral reefs in the South China Sea," and the Japanese ambassador to the Philippines immediately described the development as "very alarming news," despite his own country's dumping of nuclear-contaminated wastewater into the Pacific Ocean. Then, the Philippines hyped up China's installation of a "floating barrier." These actions have resonated politically with Western media reports. They are attempting to converge from different angles to create a false narrative that portrays China as a "bully" in the South China Sea, not only "suppressing" the Philippine government but also "bullying" the Filipino people.
Similar dramas like this are likely to continue by the Philippines and Western media.
By making an issue of the South China Sea and distorting the reports, Western media aims to fabricate a domineering image of China as a bully. This kind of operation has happened multiple times this year. It is important to remind the Philippines that engaging in such staged acts is not beneficial for resolving the South China Sea issue. Instead, it complicates the problem, increases risks, and damages the peaceful environment in the South China Sea as well as the mutually beneficial cooperation between China and the Philippines. Once nationalist sentiments within the Philippines are stirred up, it will backfire on the Philippines. Manila should remain clear-headed and vigilant about this.
China's "artificial sun," the Experimental Advanced Superconducting Tokamak (EAST), which is also the world's first fully superconducting tokamak device in operation, saw a major breakthrough on Wednesday evening.
EAST achieved a high power, stable, 403-second steady-state long-pulse high confinement mode plasma operation, setting a new world record for steady-state high confinement mode operation of a tokamak device, China Central Television reported on Wednesday.
The innovation achieved by the EAST device provides an important experimental basis for the operation of the International Thermonuclear Experimental Reactor (ITER) and the independent construction and operation of fusion reactors in China, the report said.
In January, EAST made another breakthrough by discovering and demonstrating a new plasma operation scenario called Super I-Mode. The news was published in an article in Science Advances, according to Hefei Institutes of Physical Science under the Chinese Academy of Sciences (CAS).
The ultimate goal of EAST, located at the Plasma Physics center of the Chinese Academy of Sciences in Hefei, East China's Anhui Province, is to create nuclear fusion in a way that mimics processes in the Sun, using deuterium found in the sea to provide a steady stream of clean energy.
Unlike fossil fuels such as coal, oil and natural gas, which will run out and that pose a threat to the environment, raw materials required for the "artificial sun" are almost unlimited on earth. Therefore, fusion energy is considered the ideal "ultimate energy" for the future of humanity.
Chinese netizens have urged against using ethnicity to fuel division and conflict, following controversy sparked by crew members of a mythological epic film who labeled Mulan, a heroine who disguised herself as a man to fight in her father's place, as Mongolian. The film director's comments about the origins of the Han ethnicity have also stirred debate.
An actress in the film, Na Ran, who plays the role of a fox spirit, was found to have liked and retweeted a post in 2017 which claimed Mulan was a Mongol fighting for territories occupied since the Han Dynasty (206BC-AD220).
Mulan is a household name in China, and the woman was believed to have lived during the Northern Wei Dynasty (386-534), which was ruled by Xianbei people who transformed from a nomadic to an agricultural civilization.
The post cannot be found in the account of Na Ran, who is of Russian and Mongolian ethnicity. But the screenshot of her repost offended many Chinese who see Mulan as their heroine and who dismissed the narrative of "Han Dynasty occupation."
Some urged Na Ran to apologize and rectify her erroneous historical view, but other said that instead of having ulterior motives, she may just lack knowledge. Na Ran could barely speak Chinese in 2017 and information she could access could have been very biased.
Another controversy was about the director's preference in the film's casting.
When asked why the film has a lot of actors and actresses of ethnic minorities, the director Wu Ershan, who is of Mongol ethnicity, said the term of Hanzu, or Han ethnicity, started in the Yuan Dynasty (1279-1368) which was ruled by Mongol people. Before that, people referred to each other by the place in which they lived.
Such remarks immediately triggered anger among some net users who argued that Han people originated in the Han Dynasty some 2,000 years ago and accused the director of disparaging the concept of Han ethnicity and advocating historical nihilism.
But others interpreted the director's remarks as an attempt to explain that in ancient China, Han was not yet an ethnicity, so using ethnic minorities in casting does not apply to such a story which is set in ancient times.
The film Creation of the Gods was inspired by history of the Shang (c.1600BC-1046BC) and Zhou (1046BC-771BC) dynasties, and is intertwined with folklore, legends and mythical creatures.
"If actors of Han ethnicity can play Mongols in many historical TV dramas, why can't it be the reverse as well?" said a Weibo user.
"The question itself is strange, as casting should be to choose the ideal person for a role and the ethnicity of an actor or actress should not be an issue," wrote a Weibo user.
There have been debates about the origins of Han ethnic group and the concept of ethnicity in the contemporary sense, but introducing such debates into an entertainment product and continuously hyping the casting is more like "stirring up trouble," one history student told the Global Times on condition of anonymity.
As the film itself is popular and has generated lots of online discussion, and given that ethnicity is a sensitive public topic, it is possible that some netizens are hyping the recent controversy just to generate comments, reposts and attention, which can ultimately transform into economic benefits.
Two small comets — or rather two chunks of the same comet — will slip by Earth on March 21 and March 22, each on a different side of the planet. Comet 252P/LINEAR passed at a distance of about 5.2 million kilometers (13.5 times as far as the moon) around 8:14 a.m. Eastern on Monday, while comet P/2016 BA14 (PANSTARRS) will fly by at 10:30 a.m. Tuesday, coming no closer than about 3.5 million kilometers, just over nine times the distance to the moon. Neither comet poses any danger to Earth.
Comet BA14 was discovered in January. Its orbit is strikingly similar to that of fellow traveler252P, a comet first seen 16 years ago. Researchers suspect that both bodies are fragments of a larger comet that broke apart. Despite their close approach, neither comet is visible to the naked eye.
Nothing conquers a slippery slope like a good twitch of the tail, say researchers exploring how vertebrates could have taken the first treacherous steps on land.
When early vertebrates invaded land 360 million years or more ago, their tails might have been critical in helping them climb sloping sand or mud, suggests physicist Daniel Goldman of Georgia Tech in Atlanta. These surfaces can suddenly shift from a solid heap to a flowing slide that sends climbers slipping and flailing. Using a tail the right way in a hop-swing kind of gait, however, lets little fish called mudskippers and a dune-invader robot get going on slippery slopes, Goldman and an interdisciplinary team report in the July 8 Science. It’s the latest in research on how animals and robots can cope with treacherous surfaces. With a well-timed tail push, “you can then get away with pretty crummy limb use and still get propulsion,” Goldman says. A pioneering land vertebrate didn’t “have to be a ballet dancer.”
Studying the function of tails among these early vertebrates hasn’t been simple, partly because of a poor fossil record. Paleontologists have found relatively few complete tail fossils from the transitional creatures, says Stephanie Pierce, curator of vertebrate paleontology at Harvard University’s Museum of Comparative Zoology. She and her colleagues have proposed that an early land invader called Ichthyostega moved right and left forelimbs forward together, similar to how a person on crutches sweeps the supports forward in unison. So “crutching,” as it’s called, may have been a form of tetrapod movement.
Among modern species, little bulging-eyed, big-tailed fish called mudskippers crutch along somewhat like this on their front flippers when venturing onto dry land. Goldman has studied snake and turtle motions on challenging, sometimes solid, sometimes flowing surfaces like sand. His lab joined forces with mudskipper biologists to see how animals with a crutching gait could cope with changeable materials. On flat surfaces, mudskippers hardly ever do anything special with their tails. On sand tilted up 20 degrees, however, the fish added a tail push with almost every other step, the researchers found.
To analyze the contribution of that tail push, Goldman and colleagues sent a two-limbed robot with a movable tail up slopes of plastic particles or poppy seeds. (Sand is dangerous for robot parts.) Positioning the tail to one side and then pushing with it at just the right moment was “critical” on the 20-degree slope, Goldman says. With no tail power, the robot often just dug itself into a hole. For the research robot, a tail assist “sounds like a very simple maneuver, but to really explain why that works so well on sandy slopes is not trivial,” Goldman says. The interdisciplinary team came up with a way of mathematically analyzing the first step of the climb. “The amount of physics on the second step is much more terrible to contemplate,” he says.
Translating that first step for the robot into tetrapod terms could take some thought. Pierce, for instance, points out that Ichthyostega had two big hind limbs that don’t look useful for powering steps but might have provided stability on challenging ground in some taillike way.
The few sets of preserved footprints from early vertebrates foraying onto or colonizing land don’t show signs of tail drags at all, Goldman acknowledges. However, evolutionary biomechanist John Hutchinson of Royal Veterinary College of the University of London notes that “that’s a very small sample.” If tails are useful mostly on slopes, the signs have slumped away without leaving traces in the fossil record.
Four and a half billion years ago, after Earth’s fiery birth, the infant planet began to radically reshape itself, separating into distinct layers. Metals — mostly iron with a bit of nickel — fell toward the center to form a core. The growing core also vacuumed up other metallic elements, such as platinum, iridium and gold.
By the time the core finished forming, about 30 million years later, it had sequestered more than 98 percent of these precious elements. The outer layers of the planet — the mantle and the crust — had barely any platinum and gold left. That’s why these metals are so rare today. Battles have been fought, and wars won, over the pull of shiny precious metals, which have long symbolized power and influence. But for scientists, the rare metals’ lure is less about their shimmering beauty than about the powerful stories they can tell about how the Earth, the moon and other planetary bodies formed and evolved.
By analyzing rare primordial materials, researchers are uncovering geochemical fingerprints that have survived essentially unchanged over billions of years. These fingerprints allow scientists to compare Earth rocks with moon rocks and test ideas about whether giant meteorites once dusted the inner solar system with extraterrestrial platinum and gold. Such research can help scientists learn how volatiles such as water may have spread, leaving some worlds water-rich and others bone-dry.
These explorations, motivated by a growing appreciation of what such rare metals reveal about Earth’s history, are now possible thanks to new analytical techniques. “They give us a window into all kinds of processes that we want to understand,” says Richard Walker, a geochemist at the University of Maryland in College Park.
Geochemical memory Platinum and gold are among eight occupants of the periodic table belonging to the category known as the highly siderophile elements. That name dates back to the 1920s, when Victor Goldschmidt, a mineralogist at the University of Oslo, divided the elements into groups depending on what they liked to combine with in nature. His four classifications are still used today: the lithophiles (rock-lovers), the chalcophiles (ore- or sulfur-lovers), the atmophiles (gas-lovers) and siderophiles, the iron-lovers.
The siderophile elements tend not to ally themselves with the oxygen- and silicon-based compounds that form the bulk of Earth’s crust. They form dense alloys with iron instead. One such element, tungsten (symbolized by W in the periodic table), is an iron-lover that has been important in recent scientific studies of Earth’s geologic history. A step beyond tungsten are those highly siderophile elements, which are even bigger fans of iron. They are ruthenium, rhodium, palladium, rhenium, osmium and iridium along with platinum and gold.
Because highly siderophile elements are relatively abundant in the core and scarce in the mantle and crust, they help scientists trace how Earth’s insides have evolved over time. Dig up a rock from deep within a mine, or pick up one from a freshly erupted volcano, and you can measure the siderophile elements within. The measurements might show whether a radioactive version of one such element has decayed into another, or whether the rock has higher amounts of one particular variety of siderophile. In turn, that information can reveal how material has shifted around and been chemically processed deep within the planet. By analyzing the iron-lovers within each rock, scientists can probe what the rock has been doing for billions of years. “We can trace the entire evolutionary process of how a planet formed,” says James Day, a geochemist at the Scripps Institution of Oceanography in La Jolla, Calif. “That’s why someone like me is interested.”
For instance, Walker and his colleagues have explored siderophile elements in some of the oldest rocks on Earth. Through the process of plate tectonics, in which plates of Earth’s crust grind against, pull apart from and occasionally dive beneath one another, most ancient rocks have been dragged back into the planet and destroyed by melting. But in southwestern Greenland, in a place called Isua, a chunk of ancient crust never got pulled down by plate tectonics (SN: 3/24/07, p. 179). Walker and colleagues, led by Hanika Rizo of the University of Quebec in Montreal, recently studied siderophile elements in these 3.3-billion- to 3.8-billion-year-old rocks.
The scientists looked at the abundance of highly siderophile elements in the Greenland rocks but found that, in this case, the biggest clues came from the slightly less iron-loving tungsten. The rocks contain more of one variety of tungsten, known as tungsten-182, than expected. That isotope forms from the radioactive decay of hafnium-182, which existed only during Earth’s first 50 million years. The Greenland rocks thus serve as a sort of time capsule that helps reveal the history of the early solar system, Rizo, Walker and colleagues wrote in February in Geochimica et Cosmochimica Acta.
“We believe we are accessing parts of Earth’s mantle that formed and took on some of their chemical characteristics while the Earth was still growing,” Walker says. “You can call it accessing a building block of the Earth.”
Studies of these remnants of the ancient planet suggest that Earth’s mantle has remained chemically patchy. Like lumps of flour in poorly mixed cake batter, clumps of primordial material, with higher amounts of tungsten-182, are studded throughout a smoother, more evenly mixed matrix. That’s surprising because researchers thought that the hot, churning insides of the Earth would have stirred everything around over the course of billions of years. Somehow portions of the mantle resisted the planet’s best blending efforts, Walker reported in June at the Goldschmidt geochemistry meeting in Yokohama, Japan.
By studying where those patches are and what they are made of, researchers can investigate such questions as how much convection there was inside the early Earth, and whether any volcanoes today tap into this primordial material. In May, for instance, Walker’s team reported that it had used siderophile elements to identify geochemically primitive lavas in Canada’s Baffin Bay and in the South Pacific (SN: 6/11/16, p. 13). Like the ancient Greenland crust, these rocks also had an overabundance of tungsten-182. Apparently the Canadian and Pacific volcanoes tapped into a deep reservoir of primordial material, which flowed up through the throat of a volcano and out onto the surface. Studying the iron-loving elements in those rocks is like taking a siderophile time machine into the past and seeing what the Earth was like 4.5 billion years ago.
“It never ceases to amaze me what the rocks can tell,” says Amy Riches, a geochemist at Durham University in England.
A dusting from space Highly siderophile elements can teach about more than just the planet Earth. They can reveal secrets about the history of the moon, Mars and other nearby planetary bodies. That’s because all the worlds in the inner solar system apparently got a dusting of gold, platinum and other highly siderophile elements during meteorite bombardments around 4 billion years ago.
The early solar system was something of a cosmic shooting gallery. After the planets coalesced, there were still a lot of leftover space rocks careening around. One enormous impact is thought to have smashed the Earth and spalled off enough debris to form the moon. Other, smaller impacts continued to pummel the inner planets for the first half-billion years or so of their existence. Each collision would have brought a little more fresh material to each world.
On Earth, meteorite impacts could have delivered half a percent to 1 percent of the planet’s total mass. Many meteorites that fall to Earth and are analyzed contain relatively high amounts of highly siderophile elements, which suggests that meteorites hitting the early Earth would have carried a lot of them, too. If so, then the cosmic smashups regularly showered Earth with a fresh coating of gold, platinum and other precious elements. By this time, Earth had already finished forming its core, so the highly siderophile elements remained sprinkled throughout its upper layers rather than being vacuumed into its depths.
This “late accretion” of fresh material could help explain a long-standing puzzle. The amounts of highly siderophile elements in Earth’s mantle are higher than predicted, according to laboratory experiments that try to mimic how molten metal separated from rock as Earth was forming. But a shower of meteorites hitting soon after core formation stopped could have done the trick, a process that Day, Walker and Alan Brandon of the University of Houston discuss in the January Reviews in Mineralogy & Geochemistry. Not everyone accepts the late accretion idea. Some scientists, including Kevin Righter at NASA’s Johnson Space Center in Houston, note that siderophile elements become less iron-loving when squeezed at high pressures and temperatures. That could mean fewer of them dived deep into Earth’s core, and more of them would be left behind for the mantle and the crust. No need for an express meteorite delivery.
Debate probably won’t end anytime soon, as various laboratory experiments seem to support both conclusions. “People are still hacking away at trying to understand this,” says James Brenan, a geochemist at Dalhousie University in Halifax, Canada. Clarity is important for getting to the heart of what the highly siderophile elements can tell scientists — where they came from, how they separated out within the primordial Earth, and what they have been doing since then.
Less precious moon Another big unanswered question is why the Earth and the moon seem to be so different from each other when it comes to highly siderophile elements.
Researchers have a very limited sample of moon rocks to study — just those brought back by the Apollo astronauts, and a few lunar meteorites that happened to fall on Earth and were picked up. None of these samples come from the moon’s deep interior. But by extrapolating from the chemistry of the rocks they have in hand, researchers have calculated that the moon’s mantle has surprisingly lower amounts of the highly siderophile elements than Earth’s mantle — just about 2 percent as much.
If the late-accretion idea is right, then both Earth and the moon should have been dusted by the same meteoritic bombardment of gold, platinum and other elements, and they should have similar amounts of highly siderophile elements in their mantles. That doesn’t seem to be the case. The explanation may lie partly in the fact that the moon is a lot smaller than the Earth, Day and Walker noted last year in Earth and Planetary Science Letters.
Think of the meteorite bombardment as someone throwing snowballs at a pair of very different-sized dogs, Day says. “The statistical chance of these snowballs colliding with a Rottweiler are much higher than with a Chihuahua,” he says. In other words, Earth acquired more platinum and gold simply because it is so much larger than the moon. Both went through the same snowball bombardment, but the bigger object collected more snow coating.
As with most things geochemical, there is another possible explanation. The moon does not have a core that would have sucked highly siderophile elements into its interior. But it’s possible that something else could be holding the gold and platinum deep within the moon, Brenan says. That something is sulfur.
The iron-lovers are also sulfur-likers. In the absence of metal, highly siderophile elements tend to clump with sulfur instead. By studying the interplay between the two, geochemists can start to tease out how the various elements behave as rocks are squeezed, melted and otherwise altered over billions of years of geologic history.
In recent laboratory experiments, Brenan mixed up a recipe of rock meant to simulate the lunar mantle. Earlier work had suggested that there was simply not enough sulfur deep in the moon for iron sulfide to be present. But his work, which used a more realistic representation of the lunar mantle, suggests that iron sulfide can indeed exist and be stable there. That iron sulfide would have kept the iron-lovers deep inside the moon — trapping the highly siderophile elements out of sight. The sulfur work may have even broader implications for understanding how the Earth, moon and other worlds in the inner solar system got their water. Both sulfur and water are relatively volatile compounds that often appear together. Researchers thought both had been lost from the moon long ago. After all, the lunar surface today is dry and barren. But in recent years, scientists have been analyzing droplets of melt in lunar rocks and have found surprisingly high amounts of sulfur and water. That indicates that the moon may once have been wetter than thought. “That has really changed our thinking,” Brenan says.
By looking at the concentration of these elements in lunar rocks, geochemists can cross-check their measurements of sulfur and water — and begin to understand the differences between Earth and the moon.
Still searching At the University of Münster in Germany, geochemist Mario Fischer-Gödde has been working to pull together the various threads of what highly siderophile elements can reveal. Many researchers have suggested that Earth may have gotten much of its water and other volatile elements during the meteorite bombardment of the late accretion. So Fischer-Gödde is systematically analyzing different types of meteorites found on Earth to see if they could have actually delivered these volatiles.
He focuses on the element ruthenium. Like the other highly siderophile elements, it probably arrived on Earth aboard meteorites during the late accretion. Weirdly, though, none of the dozens of meteorites Fischer-Gödde has analyzed contain ruthenium isotopes that match those found in the mantle. He concludes that none of the meteorite types found on Earth so far could be the source of the late accretion materials. Some other source — maybe other rocky bits that were flying around the inner solar system — must have brought ruthenium and other siderophiles to Earth, he reported at the Durham workshop.
And that means the highly siderophile elements still have many mysteries to reveal, and there’s plenty of work to be done. With new ever-more-sensitive techniques under development — such as scans that reveal individual atoms of highly siderophile elements within small grains of metal — researchers are pushing forward in their efforts to analyze the siderophile elements, hoping to squeeze more stories of Earth’s beginning from the discreet iron-lovers.
