XPost: alt.astronomy, alt.fan.heinlein

Really! Compared to planets our moon is quite small.
Interesting that they say it still has 'hot spots'.

from https://www.seattletimes.com/nation-world/scientists-have-found-a-hot-spot-on-the-moons-far-side/
(Go to the citation to see the photos and maps.)

Scientists have found a hot spot on the moon’s far side
July 18, 2023 at 5:05 pm
A small portion of the Compton-Belkovich volcanic complex on the moon.
The upper two-thirds of the scene shows the volcanic complex; the lower
third of the image is outside of the complex. (NASA/GSFC/Arizona State University via The New York Times)
In an undated image provided by Jolliff et al, 2011, a composite image
shows the presence of thorium in the Compton-Belkovich volcanic complex
made with data from the Lunar Prospector, a space mission launched in
1998. (Jolliff et al, 2011 via The New York Times)

1 of 4 | A small portion of the Compton-Belkovich volcanic complex on
the moon. The upper two-thirds of the scene shows the volcanic complex;
the lower third... More
By KENNETH CHANG
The New York Times
The rocks beneath an ancient volcano on the moon’s far side remain surprisingly warm, scientists have revealed using data from orbiting
Chinese spacecraft.

They point to a large slab of granite that solidified from magma in the geological plumbing beneath what is known as the Compton-Belkovich
Volcanic Complex.

“I would say we’re putting the nail in the coffin of this really is a volcanic feature,” said Matthew Siegler, a scientist at the Planetary
Science Institute, headquartered in Tucson, Arizona, and who led the
research. “But then what’s interesting is, it’s a very Earth-like volcanic feature.”

The findings, which appeared early this month in the journal Nature,
help explain what happened long ago beneath an odd part of the moon. The
study also highlights the scientific potential of data gathered by
China’s space program, and how researchers in the United States have to circumvent obstacles to use that data.

For this study, Siegler and his colleagues analyzed data from microwave instruments on Chang’e-1, launched in 2007, and Chang’e-2, launched in 2010, two early Chinese spacecraft no longer in operation. Because
Congress currently prohibits direct collaboration between NASA and China
and the research was financed by a NASA grant, Siegler could not work
with scientists and engineers who collected the data.

“That was a limitation, that we couldn’t just call up the engineers that had built the instrument in China and say, ‘Hey, how should we be interpreting this data?’” he said. “It would be really great if we could just have been working on this with the Chinese scientists the whole
time. But we’re not allowed to. But, luckily, they made some of their databases public.”

Siegler was able to tap into the expertise of a Chinese scientist,
Jianqing Feng, whom he had met at a conference. Feng was working on a
lunar exploration project at the Chinese Academy of Sciences.

This image shows the Compton-Belkovich volcanic complex on the moon’s
far side, with the boxed area indicating a large granite zone, which
could not be picked up by topography. (Matthew Siegler/Planetary Science Institute/Nature via The New York Times)

This image shows the Compton-Belkovich volcanic complex on the moon’s
far side, with the boxed area indicating a large granite zone, which
could not be picked up by topography. (Matthew Siegler/Planetary Science Institute/Nature... More
“I realized that combining the lunar exploration data from different countries would deepen our understanding of lunar geology and make
exciting findings,” Feng said in an email. “Therefore, I quit my job in China, moved to the United States, and joined Planetary Science Institute.”

The Chinese orbiters both had microwave instruments, common on many Earth-orbiting weather satellites but rare on interplanetary spacecraft.

The data from Chang’e-1 and Chang’e-2 thus provided a different view of
the moon, measuring the flow of heat as far as 15 feet below the surface
— and proved ideal for investigating the oddity of Compton-Belkovich.

Visually, the region looks unremarkable. (It does not even have a name
of its own; the hyphenated designation is derived from two adjoining
impact craters, Compton and Belkovich.) The region has nonetheless
fascinated scientists for a couple of decades.

In the late 1990s, David Lawrence, then a scientist at Los Alamos
National Laboratory, was working on data collected by NASA’s Lunar
Prospector mission and noticed a bright spot of gamma-rays shooting from
this location on the moon’s far side. The energy of the gamma-rays, the highest energy form of light, corresponded to thorium, a radioactive
element.

“It was one of these oddball places that just stood out like a sore
thumb in terms of the thorium abundance,” said Lawrence, now a planetary scientist at the Johns Hopkins Applied Physics Laboratory in Maryland.
“I’m a physicist. I’m not an expert in lunar geology. But even as a physicist, I saw that stand out and said, ‘OK, this is something worth further study.’”

In an undated image provided by Jolliff et al, 2011, a composite image
shows the presence of thorium in the Compton-Belkovich volcanic complex
made with data from the Lunar Prospector, a space mission launched in
1998. (Jolliff et al, 2011 via The New York Times)

In an undated image provided by Jolliff et al, 2011, a composite image
shows the presence of thorium in the Compton-Belkovich volcanic complex
made with data from the Lunar Prospector, a space... (Jolliff et al,
2011 via The New York Times)More
The next revelations came after the arrival of NASA’s Lunar
Reconnaissance Orbiter in 2009. Brad Jolliff, a professor of earth and planetary sciences at Washington University of St. Louis, led a team
that examined high-resolution images of Compton-Belkovich.

What they saw “looked suspiciously like a caldera,” Jolliff said
referring to the remnants of a volcano’s rim. “If you consider these features are billions of years old, they are remarkably well preserved.”

A more recent analysis led by Katherine Shirley, now at the University
of Oxford in England, estimated the age of the volcano at 3.5 billion
years old.

Because the lunar soil acts as a good insulator, dampening the
temperature variations between day and night, the microwave emissions
largely reflect the flow of heat from the moon’s interior. “You only
need to go about two meters below the surface to stop seeing the heat
from the sun,” Siegler said.

At Compton-Belkovich, the heat flow was as high as 180 milliwatts per
square meter, or about 20 times the average for the highlands of the
moon’s far side. That measure corresponds to a temperature of minus 10 degrees Fahrenheit about six feet below the surface, or about 90 degrees
warmer than elsewhere.

“This one stuck out, as it was just glowing hot compared to anywhere
else on the moon,” Siegler said.

To produce that much heat and the thorium gamma-rays, Siegler, Feng and
the other researchers concluded that granite, which contains radioactive elements like thorium, was the most likely source and that there had to
be a lot of it.

“It seems to nail down more particularly what kind of material is really underneath,” said Lawrence, who was one of the reviewers of the paper
for Nature.

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“It’s sort of a tip-of-the-iceberg type of thing,” he said of the original gamma-ray emissions. “What you see at Compton-Belkovich is sort
of a surface expression of something a lot bigger underneath.”

Volcanism is evident elsewhere on the moon. Plains of hardened lava —
the mare, or seas, of basalt — cover vast swaths of the surface, mostly
on the near side. But Compton-Belkovich is different, resembling certain volcanoes on Earth, like Mount Fuji and Mount St. Helens, that spew more viscous lava.

A small portion of the Compton-Belkovich volcanic complex on the moon.
The upper two-thirds of the scene shows the volcanic complex; the lower
third of the image is outside of the complex. (NASA/GSFC/Arizona State University via The New York Times)

A small portion of the Compton-Belkovich volcanic complex on the moon.
The upper two-thirds of the scene shows the volcanic complex; the lower
third of the image is outside of the complex. (NASA/GSFC/Arizona State University via The New... More
Granite appears to be scarce elsewhere in the solar system. On Earth,
granite forms in volcanic regions where oceanic crust is pushed down
beneath a continent by plate tectonics, the geological forces that are
pushing around pieces of the Earth’s outer crust. Water is also a key ingredient for granite.

But the moon is mostly dry and lacks plate tectonics. The moon rocks
brought back by NASA astronauts more than 50 years ago contained only a
few grains of granite. But the data from the Chinese orbiters suggests a formation of granite more than 30 miles wide below Compton-Belkovich.

“Now we need the geologists to figure out how you can produce that kind
of feature on the moon without water, without plate tectonics,” Siegler
said.

Jolliff, who was not involved with the research, said the paper was “a
very nice new contribution.” He said he hoped NASA or another space
agency would send a spacecraft to Compton-Belkovich for seismic and mineralogical measurements.

Such a mission could help test ideas about how a volcano formed there in
the first place. One hypothesis is that a plume of hot material rose up
from the mantle beneath the crust, much as what occurs under the
Hawaiian islands.

Feng’s visa allowing him to work in the United States is expiring soon.
He is applying for a new one, navigating his scientific career amid
U.S.-China geopolitical wrangling.

“We are starting to study other potential granitic systems on the moon now,” he said. “Also, we will expand our models to explore the icy moons
of Jupiter. Therefore, I am trying to stay in the United States as long
as possible.”

This story was originally published at nytimes.com. Read it here.
The Seattle Times does not append comment threads to stories from wire
services such as the Associated Press, The New York Times, The
Washington Post or Bloomberg News. Rather, we focus on discussions
related to local stories by our own staff. You can read more about our community policies here.

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