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China's Chang'e-5 mission offers new insights into evolution of Moon – CCTV

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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.

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Government intervention needed to save endangered night sky, says scientist – CBC.ca

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Samantha Lawler lives in the small village of Edenwold, Sask. It’s “a place that’s so dark that I can walk out my back door and see the Milky Way,” she said.

But that deep darkness won’t last, as companies like SpaceX’s Starlink and Amazon’s Project Kuiper proceed with plans to launch tens of thousands of satellites into orbit, forming “mega-constellations” of satellites.

She knows exactly what that could look like, because she’s been working on simulations of satellites in the night sky.

“Every night I can see probably a few satellites in a few-minute period. And I know that’s going to increase a lot,” Lawler, an assistant professor of astronomy at the University of Regina, told As It Happens host Carol Off.

Her model relies on the planned or actual orbits of 65,000 satellites from four major companies: Starlink, Project Kuiper, OneWeb and StarNet/GW. The majority of these satellites have not yet been launched, but there are already nearly 4,000 operational satellites in orbit, Lawler noted.

According to our simulations, which take into account the brightness of satellites reflecting sunlight and the orbits that these companies want to use, I predict that there will be a couple of hundred satellites visible at any time during the summer in my night sky and within a couple hours of sunrise and sunset all year long,” she said.

The companies filed plans with the U.S. Federal Communications Commission and the International Telecommunications Union that detail the angles of the orbits and how many satellites would be on each orbit. As a result, Lawler and her colleagues are able to predict where the satellites will be in the sky as viewed from different locations on Earth at different times of year, and estimate how much light they’ll reflect.

They relied on observations of existing Skylink satellites at the Plaskett Telescope in Victoria, B.C. to help calibrate their model.

Samantha Lawler says that people living close to 50 degrees north will be most affected by plans to launch tens of thousands of satellites into space in the next few years. (Campion College, University of Regina/Submitted by Samantha Lawler )

“We really wanted to make sure that our model is applicable to Canada. We want to know what’s going to happen to our skies,” she said.

According to her research, people living along 50 degrees of latitude north and south will be most affected by visible satellites and other night sky light pollution. The north latitude line runs across some Canadian cities including Vancouver, Winnipeg and Calgary.

If 65,000 satellites are launched into space and the industry isn’t regulated, the could drown out the light from actual stars, of which we can usually only see a few thousand with the naked eye, she said.

“If you have a couple hundred satellites [visible] at all times, that means that one out of every 15 points in the sky will actually be moving. It’ll be very disorienting,” said Lawler. 

Making satellites fainter

So many moving visible satellites pose enormous challenges for research, to say nothing of the amount of pollution they’ll cause, said Lawler.

Some of them “will completely die in orbit and then they’ll just become space junk,” while others will burn up in the upper atmosphere, she explained. She noted that they’re mostly made of aluminum, and that we have no information on what such a large increase of burning aluminum will do the upper atmosphere.

WATCH | What a future with a sky full of satellite mega-constellations could look like

[embedded content]

Lawler said that instead of launching their own satellites to support their respective internet services, companies should be forced to share infrastructure, whether by government action or other forms of regulation. Failing that, they could at least be forced to ensure their devices don’t reflect so much light.

There are fantastic engineers who work for all of these companies, but right now they have absolutely no incentive to make their satellites fainter, so they’re not doing it,” said Lawler. “Starlink, to their credit, has tried. They put a tiny bit of effort into making their satellites a little bit fainter, but they’re still very much naked-eye visible.”

Lawler says that governments must push forward legislation at a federal level, but she also notes that consumers do have some power.

“If you have another option for good internet, don’t buy satellite internet. If … satellite internet is the only the only option that you have, tell your company, tell your provider that you care about the night sky, that it’s important to you that they put effort into engineering their satellites to be fainter,” she said.

She also notes that putting pressure on local governments can be effective too.

A lot of the lack of internet infrastructure in rural places is from many years of neglect by local governments, by provincial governments. If we pressure our governments into investing more in alternate forms of … internet [access], then there wouldn’t be so much demand for this.”


Written by Andrea Bellemare. Interview produced by Chloe Shantz-Hilkes. 

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Spacewalking astronauts replace antenna after debris scare – Phys.Org

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This photo provided by NASA shows astronaut Tom Marshburn replaces a broken antenna outside the International Space Station after getting NASA’s all-clear for orbiting debris, on Thursday, Dec. 2, 2021. Marshburn and Kayla Barron completed the job Thursday. Credit: NASA via AP

Spacewalking astronauts replaced a broken antenna outside the International Space Station on Thursday after getting NASA’s all-clear for orbiting debris.

U.S. astronauts Tom Marshburn and Kayla Barron were supposed to complete the job Tuesday, but NASA delayed the spacewalk because of potentially threatening space junk. NASA later determined the astronauts were safe to go out, despite a slightly increased risk of a punctured suit from satellite wreckage.

But soon after the spacewalk ended, Mission Control notified the crew that the station would need to move into a slightly lower orbit Friday to avoid an old U.S. rocket fragment.

Last month, Russia destroyed an old satellite in a missile test, sending pieces everywhere. NASA isn’t saying whether that event was the source of the junk that delayed the spacewalk.

During the first National Space Council meeting under Vice President Kamala Harris this week, top U.S. government officials joined her in condemning Russia’s extensive debris-scattering last month. More than 1,700 sizable pieces of the shattered satellite are being tracked, with tens if not hundreds of thousands too small to see.

Barron reported at least 11 small debris strikes to the failed antenna that was removed during the spacewalk, with some of the holes looking old. The device—up there for more than 20 years—malfunctioned in September.

Marshburn, 61, became the oldest person to conduct a spacewalk. It was the fourth of his career. Barron, a 34-year-old space rookie, ventured out on her first. They flew up on SpaceX last month for a six-month stay. Two other Americans are aboard the space station, along with two Russians and one German.


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Space junk forces spacewalk delay, too risky for astronauts


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retrieved 3 December 2021
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SpaceX launches 48 more Starlinks and two Earth-imaging satellites – CBS News

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A SpaceX Falcon 9 rocket boosted 48 more Starlink internet relay satellites into orbit Thursday, along with two BlackSky commercial Earth-imaging satellites. The flight marked the 27th Falcon 9 launch so far this year, a new record for the California-based rocket builder.

A SpaceX Falcon 9 rocket blasts off from the Cape Canaveral Space Force Station carrying 48 Starlink internet relay stations and two BlackSky Earth-imaging satellites.

William Harwood/CBS News


The Falcon 9’s first stage booster, making its ninth flight, thundered to life at 6:12 p.m. EST, smoothly pushing the 229-foot-tall rocket away from pad 40 at the Cape Canaveral Space Force Station atop 1.7 million pounds of thrust.

Eight minutes and 45 second later, the second stage and its 50-satellite cargo were safely in orbit. Just under an hour later, the two BlackSky satellites were released, followed by the 48 Starlinks about 25 minutes after that.

Meanwhile, the Falcon 9’s well-traveled booster successfully landed on an off-shore droneship to chalk up SpaceX’s 96th successful recovery, and its 73rd at sea.

120221-plume.jpg
The nine first stage engines in the Falcon 9 booster put on a colorful show as the rocket climbed out of the lower atmosphere and the exhaust plume expanded in the lower pressure environment.

SpaceX


SpaceX has now launched 1,892 Starlinks as it populates a globe-spanning commercial constellation of internet relay satellites designed to provide broadband service to users anywhere in the world. Going into Thursday’s launch, 1,684 Starlinks were believed to be operational.

The two BlackSky imaging satellites joined eight others already in orbit, with two more scheduled for launch from New Zealand atop a Rocketlab booster later this month. BlackSky provides high-resolution imagery to commercial users as well as U.S. military and intelligence agencies.

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