BEIJING, Oct. 19 (Xinhua) — Chinese researchers have studied the
lunar samples brought back by the Chang’e-5 mission and dated the
youngest rock on the Moon at around 2 billion years in age, extending
the “life” of lunar volcanism 800-900 million years longer than
previously known.
The study, conducted mainly by a research team at the Institute of
Geology and Geophysics (IGG), Chinese Academy of Sciences (CAS), was
presented in three Nature papers and published online Tuesday.
Last year, China’s Chang’e-5 mission retrieved samples from the Moon
weighing about 1,731 grams, which were the first lunar samples in the
world in over 40 years.
“The Chang’e-5 mission was a success and the lunar samples brought
back shed new light on the evolution of the Moon,” said Li Xianhua, an
academician with CAS who led the research team.
DATING MOON ROCKS
“The magma of the Moon has solidified, and the Moon’s geologic
activity has already ceased. When the Moon’s volcanic activity stopped,
it emerged as one of the major issues in its evolutionary history,” said
Li Qiuli, head of the secondary ion mass spectrometry laboratory of
IGG.
The youngest dated rock from the Apollo and Luna missions and lunar
meteorites was around 2.8-2.9 billion years old. However, more samples
are needed and one of the Chang’e-5 tasks is to explore the youngest
magmatic activity of the Moon.
“The dimply surface we see when we look up at the Moon through a
telescope is due to the fact that many asteroids have collided with it
over billions of years. Older rocky regions have experienced more impact
craters over time, and regions with younger rocks have fewer craters,”
said Li Qiuli.
Using the method of chronology known as crater counting, researchers
inferred that the Oceanus Procellarum, the landing site of the Chang’e-5
mission, was most likely to have been witness to one of the Moon’s last
volcanic eruptions. Researchers could then calibrate the results from
crater counting with radioisotopically dated samples.
Radioisotopic dating works on the principle that radioactive elements
have constant decay rates. By measuring the relative abundances of the
parent and daughter isotopes, researchers will know how long the decay
has been taking place.
Using the microscope, researchers manually picked out rock fragments
from their 3-gram lunar samples, which is as difficult as separating
black flour from white flour by hand. Most of these minerals suitable
for dating are only one-twentieth of the diameter of a hair.
Li Qiuli said that the research team had been well-prepared for
studying the lunar samples retrieved by China, and has continuously
developed the ion probe technology in the past decade, reaching an
internationally acclaimed level of expertise.
“Our palms were sweaty as we loaded the sample and turned on the mass
spectrometer. When we saw the age it spat out, we couldn’t believe our
luck. But we wanted to be sure,” said Li Qiuli, adding that they carried
out more than 200 tests.
In total, the team analyzed 47 different rock fragments extracted
from the sample materials and dated the youngest rock on the Moon at
2.03 billion years old. The new age extends the life of lunar volcanism
800-900 million years longer than previously known.
OUT OF EXPECTATION
“The Moon is only around one percent the mass of Earth. At that
strikingly small size, theoretically, at least, it should have
completely solidified at a quick pace. Our team investigated further why
volcanic activity still existed on the Moon so late,” said Li Xianhua.
Lunar scientists focused on KREEP, an acronym built from the letters K
(for potassium), REE (for rare-earth elements) and P (for phosphorus),
which is a distinctive geochemical component of some lunar rocks.
“A widely accepted hypothesis is that radioactive elements (U, Th and
K) supplied the heat necessary for the late volcanic activity. Because
KREEP is rich in radiogenic elements U, Th and K, it is therefore
thought to be responsible for the young volcanic activity,” said Yang
Wei, a researcher with IGG.
“Isotopes are an effective way to identify the KREEP component as
they are like the DNA of a rock and will not change through the magmatic
evolution,” said Yang.
However, the difficulty lies in the small size of the basalt clasts
in the Chang’e-5 lunar samples. It is hard to obtain the isotope ratios
of the Chang’e-5 basalt.
“It’s like DNA testing, which requires a large tube of blood, but we can only use one drop,” said Yang.
Thanks to the institute’s efforts over a decade, a state-of-the-art
method for analyzing samples under high magnification has been
developed, allowing researchers to obtain the strontium and neodymium
isotope ratios of specific minerals.
The results were beyond expectations. The Chang’e-5 basalt, the
youngest basalt dated on the Moon so far, originated from a depleted
mantle source with a KREEP component measuring less than 0.5 percent of
its weight.
In other words, it is unlikely that the KREEP components in the lunar
mantle supplied the heat necessary for the late volcanic activity.
WATER CONTENT
Another possible cause of volcanic activity on the Moon at such a
late age is that the mantle source might have contained water to reduce
its melting point, said scientists.
“The water content of the lunar mantle is a key question for lunar
exploration because it provides critical constraints on the formation of
the Moon. Furthermore, since water can significantly decrease the
melting temperature of rocks, understanding its abundance is important
for understanding the history of lunar volcanism,” said Lin Yangting, a
researcher with IGG.
The large discrepancy in water abundance estimates of the lunar
mantle could be mainly attributed to the Apollo samples and lunar
meteorites being generally quite old.
Most previous lunar samples with measured water content date back to 3
billion years or earlier. Such old rocks could have undergone heavy
modifications over a long time by the impact of asteroids and particles
from the sun.
“The samples retrieved by Chang’e-5 were from a single basaltic lava
flow. With such a simple and clear geological setting, the samples,
therefore, provide a good opportunity to address the question of whether
the mantle reservoir at 2 billion years was wet or dry,” said Lin.
The research team analyzed the water contents and hydrogen isotopes
of pockets of melt preserved in some minerals as well as the mineral
apatite, which can contain water, from Chang’e-5 basalts.
“We used a nano-scale ion probe called the nanoSIMS, a secondary ion
mass spectrometer with an ion beam down to 50 nanometers in diameter.
The relative abundances of the two isotopes of hydrogen (deuterium [D]
and hydrogen [H]) can serve as a ‘fingerprint’ to trace the reservoirs
of water and the magmatic processes involved,” said Lin.
The results indicated that the mantle source of the Chang’e-5 basalts
was drier than the estimated water content based on the Apollo samples
and lunar meteorites, which rules out the possibility that high water
content in the mantle source was the cause of the usually young volcanic
eruption.
The mystery of the late lunar volcanic activity is yet to be solved.
“Our discoveries raise new questions for the future of lunar
exploration and scientists need to further explore the formation
mechanism of the lunar magma,” said Li Xianhua.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
