A huge granite mass has been discovered under the surface of the far side of the Moon.
The stone is very rare outside Earth because it takes water and plate tectonics to form and only small granules have been detected on the Moon previously.
The find mirrors the plot of the classic sci-fi film “2001: A Space Odyssey” when a mysterious monolith appears on Earth at the time of cavemen.
Extra heat picked up by a satellite led the experts to a 50-kilometre-wide dormant volcano that last erupted 3.5 billion years ago.
The NASA team believes the granite was formed by cooled magma but added the find was “unexpected” because the igneous rock is “nearly absent” in the Solar System outside Earth.
A geological expert who works at NASA, but wasn’t involved in the study, said granite – commonly used in our kitchen counters – is rare in space because it is difficult to form without water and plate tectonics.
Until now, only small grains of granite have been picked up on the Moon in samples brought back on the Apollo missions, which first landed astronauts on the natural satellite in 1969.
Experts compared the newfound space volcano to El Capitan and Half Dome in Yosemite, California, and said the results open the possibility of similar discoveries on the Moon and beyond.
Lead researcher, Dr. Matt Siegler, Planetary Science Institute, Tucson, Arizona, was confused when his team picked up the unusual heat, and brought in his geochemist wife, Dr Rita Economos, to make sense of the results.
He said: “We have discovered extra heat coming out of the ground at a location on the Moon believed to be a long-dead volcano which last erupted over 3.5 billion years ago.
“It’s around 50km (164042 feet) across, and the only solution that we can think of which produces that much heat is a large body of granite, a rock which forms when a magma body – the unerupted lava – below a volcano cools.
“Granite has high concentrations of radioactive elements like uranium and thorium compared to other rocks in the lunar crust, causing the heating we can sense at the lunar surface.
“We have been developing a method to use microwaves to remotely measure geothermal heat gradients on the Moon.
“These measurements come from the Chinese Chang’E 1 and 2 lunar orbiters with context from NASA’s Lunar Prospector and Lunar Reconnaissance Orbiters.
“This data showed a high geothermal gradient exactly coincident with a large 20 km (65616.8 feet) wide silicon-rich surface feature believed to be an extinct volcanic caldera, which is between the craters Compton and Belkovich on the far side of the Moon.
“This is around 10C warmer than its surroundings. We interpret this heat flux as resulting from a radiogenic-rich granite body below the caldera.
“To tell the truth we were a bit puzzled when we found it: fortunately, my wife, Dr Rita Economos, is the geochemist in the family, so with her guidance, we were able to piece together the probable geologic cause of the heat anomaly.
“This is more Earth-like than we had imagined can be produced on the Moon, which lacks the water and plate tectonics that help granites form on Earth.
“What this also does is show that remote sensing can pick up hidden features, and this will be useful in the exploration of other planetary bodies in the Solar System.”
Explaining the data that her husband collected from a Chinese orbital spacecraft, Dr Economos, Southern Methodist University, Dallas, Texas, reported the granite was formed when magma solidifies underground.
She said: “This find is a 50km (164042 feet) wide batholith; a batholith is a type of volcanic rock that forms when lava rises into the earth’s crust but does not erupt onto the surface.
“El Capitan and Half Dome, in Yosemite in California are examples of similar granite rocks which have risen to the surface.”
Though he was not involved in the study, Professor Elardo, a NASA Early Career Fellow and Assistant Professor at the University of Florida’s Department of Geological Sciences, claimed the findings were fascinating.
Commenting on the study published in the journal Nature, he said: “This new finding of a large mass of granite on the Moon is incredibly interesting. We have tons of granite of different flavors all over Earth.
“People don’t think twice about having a granite countertop in their kitchen. But geologically speaking, it’s quite hard to make granite without water and plate tectonics, which is why we really don’t see that type of rock on other planets.
“So if this finding by Siegler and colleagues holds up, it’s going to be massively important for how we think about the internal workings of other rocky bodies in the Solar System.”
Produced in association with SWNS Talker
Edited by Saba Fatima and Asad Ali
