By Express News Service
There is a theory that the Moon was formed when Earth and a Mars-sized planet collided some 4.51 billion years ago when the Solar System was still in its early stages. A chunk of Earth was chiselled out and settled into an orbit around it to be her sole natural satellite.
Now, this theory may gain ground with NASA scientists discovering a granite mass under the lunar surface on the far side of the Moon, which, they feel makes it more Earth-like than ever before – in other words, some features, including the process of granite formation, may have been carried away by the Moon when it separated from Earth.
Scientists have discovered a mass of granite 50km in diameter below the thorium-rich feature and an extinct volcanic caldera (a volcano that had erupted and collapsed, forming a deep crater) between the craters Compton and Belkovich on the Moon’s far side.
Although the Apollo missions brought back rock samples with traces of granite, scientists had never imagined such a large body of granite to exist below the lunar surface.
The finding was made by NASA scientists based on data gathered by the Chinese Chang’E-1 and Chang’E-2 lunar orbiters and NASA’s Lunar Prospector and Lunar Reconnaissance Orbiters.
According to lead researcher Dr Matt Siegler from NASA’s Planetary Science Institute in Tucson, Arizona, the lunar orbiters remotely used microwaves to measure geothermal heat gradients on the Moon. Geothermal gradient is the increase in temperature as depth increases.
The measurements showed higher geothermal gradients specifically under a 20 km wide silicon-rich surface feature believed to be an extinct volcano that last erupted some 3.5 billion years ago.
The heat measurements revealed that the temperatures under the surface at the site were at least 10 degrees Celsius higher than the geothermal gradients in the surrounding regions.
The peak measurements of the heat flux were found to be about 180 milliwatts per square metre, which is about 20 times higher than that of the average lunar highlands. The scientists interpreted this heat flux, attributing it to radiogenic-rich (heat caused by radioactivity) granite mass below the surface. Granite is known to have higher concentrations of radioactive uranium and thorium than in other rocks in the lunar surface, which is understood to be the cause of the heating.
From the features of the mass below the lunar surface and based on calculations and the heat features, the scientists feel it is a 50-Km wide batholith, a type of granitic volcanic rock which, on Earth, forms when lava rises to the crust but fails to erupt. Similar under-surface batholithic granite features are present on Earth in several locations, the similarity of which has caused much excitement.
Siegler, who is to present the paper on this at the Goldschmidt Conference at Lyons in France on July 12, feels there could be more such granite features elsewhere on the Moon. With manned lunar missions being planned to make a comeback in the near future, more revelations about such Earthlike geologic features on the Moon are bound to be made in time to come.
There is a theory that the Moon was formed when Earth and a Mars-sized planet collided some 4.51 billion years ago when the Solar System was still in its early stages. A chunk of Earth was chiselled out and settled into an orbit around it to be her sole natural satellite.
Now, this theory may gain ground with NASA scientists discovering a granite mass under the lunar surface on the far side of the Moon, which, they feel makes it more Earth-like than ever before – in other words, some features, including the process of granite formation, may have been carried away by the Moon when it separated from Earth.
Scientists have discovered a mass of granite 50km in diameter below the thorium-rich feature and an extinct volcanic caldera (a volcano that had erupted and collapsed, forming a deep crater) between the craters Compton and Belkovich on the Moon’s far side.googletag.cmd.push(function() {googletag.display(‘div-gpt-ad-8052921-2’); });
Although the Apollo missions brought back rock samples with traces of granite, scientists had never imagined such a large body of granite to exist below the lunar surface.
The finding was made by NASA scientists based on data gathered by the Chinese Chang’E-1 and Chang’E-2 lunar orbiters and NASA’s Lunar Prospector and Lunar Reconnaissance Orbiters.
According to lead researcher Dr Matt Siegler from NASA’s Planetary Science Institute in Tucson, Arizona, the lunar orbiters remotely used microwaves to measure geothermal heat gradients on the Moon. Geothermal gradient is the increase in temperature as depth increases.
The measurements showed higher geothermal gradients specifically under a 20 km wide silicon-rich surface feature believed to be an extinct volcano that last erupted some 3.5 billion years ago.
The heat measurements revealed that the temperatures under the surface at the site were at least 10 degrees Celsius higher than the geothermal gradients in the surrounding regions.
The peak measurements of the heat flux were found to be about 180 milliwatts per square metre, which is about 20 times higher than that of the average lunar highlands. The scientists interpreted this heat flux, attributing it to radiogenic-rich (heat caused by radioactivity) granite mass below the surface. Granite is known to have higher concentrations of radioactive uranium and thorium than in other rocks in the lunar surface, which is understood to be the cause of the heating.
From the features of the mass below the lunar surface and based on calculations and the heat features, the scientists feel it is a 50-Km wide batholith, a type of granitic volcanic rock which, on Earth, forms when lava rises to the crust but fails to erupt. Similar under-surface batholithic granite features are present on Earth in several locations, the similarity of which has caused much excitement.
Siegler, who is to present the paper on this at the Goldschmidt Conference at Lyons in France on July 12, feels there could be more such granite features elsewhere on the Moon. With manned lunar missions being planned to make a comeback in the near future, more revelations about such Earthlike geologic features on the Moon are bound to be made in time to come.
