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The historic Chandrayaan-3 mission, which made India the fourth country to land on the moon a year ago on Friday, has revealed new evidence supporting a theory about the moon’s early history.
When the mission landed in the high southern regions of the Moon, near the lunar south pole, it launched a small, six-wheeled rover called Pragyan, which means wisdom in Sanskrit. The rover was equipped with scientific instruments that allowed it to analyze particles within the lunar soil and measure elements there.
The probe made 23 measurements as it traveled along a 338-foot (103-meter)-long section of the lunar surface, located 164 feet (50 meters) from the Chandrayaan-3 landing site, for about 10 days. The probe’s data represent the first measurements of elements in lunar soil near the south pole region.
The craft was able to detect a relatively uniform composition consisting largely of a rock called iron anorthosite, which is similar to samples taken from the Moon’s equatorial region during the Apollo 16 mission in 1972.
The researchers reported the results of the study, which was published Wednesday in the journal nature.
Lunar samples help scientists solve still-standing mysteries about how the Moon evolved over time, including how it formed during the chaotic early days of the solar system.
The study authors said the presence of similar rocks in different parts of the moon provides additional support for the decades-old hypothesis that the moon was once covered by an ancient ocean of magma.
There are many theories about how the Moon formed, but scientists mostly agree that about 4.5 billion years ago, a Mars-sized body or series of bodies collided with Earth and ejected enough molten debris into space to create the Moon.
The first lunar samples collected during the Apollo 11 mission in 1969 led researchers to the theory that the Moon was once a molten ball of magma.
The 842-pound (382-kilogram) samples of lunar rock and soil returned to Earth by the Apollo missions in the late 1960s and early 1970s disproved the notions that the Moon was a celestial body trapped in Earth’s gravity, or that the Moon formed along with Earth from the same debris. The rock samples suggested that the Moon was created about 60 million years after the solar system began to form, according to NASA.
The magma ocean, likely hundreds to thousands of kilometers deep, persisted for about 100 million years, The space agency saysAs the magma ocean cooled, crystals formed within it.
Some rocks and minerals, such as iron anorthosite, rose upward to form the lunar crust and highlands, while other magnesium-rich minerals, such as peridot, sank deep below the surface into the mantle, said Noah Petro, NASA’s project scientist for both the Lunar Reconnaissance Orbiter and Artemis 3. Petro was not involved in the new study.
While the lunar crust has an average thickness of about 31 miles (50 kilometers), the lunar mantle beneath it reaches a depth of about 838 miles (1,350 kilometers).
All the minerals and rocks on the moon tell a story about the moon’s history, Pietro added.
When the Pragyan probe conducted its own investigation of the chemical composition of lunar soil, it found a mixture of iron anorthosite and other types of rock, including minerals such as peridot.
The Chandrayaan-3 landing site, known as Shiv Shakti Point, is located about 217 miles (350 kilometers) from the edge of the South Pole-Aitken Basin, which is considered the oldest crater on the moon.
The research team believes that an asteroid impact created the basin about 4.2 billion to 4.3 billion years ago, and discovered magnesium-rich minerals such as peridot, mixing them with lunar soil, said lead author Santosh Vadavalli, a professor at the Physical Research Laboratory in Ahmedabad, India.
He added that researchers continue to investigate the presence of these minerals, which likely originated in the lunar mantle, to provide more context for the moon’s origins and evolution.
This mission proves the importance of sending spacecraft to different lunar regions to understand the history of the moon, Vadavalli added.
“All previous successful moon landings have been limited to the equatorial and mid-latitude regions. Chandrayaan-3 is the first mission to successfully land in the polar regions of the Moon and perform in-situ analyses. These new measurements in previously unexplored regions have strengthened confidence in the lunar magma ocean hypothesis,” he said.
The Indian lunar exploration programme then aims to explore the permanently shadowed regions at the moon’s poles and return samples for detailed analysis in laboratories on Earth, Vadawale added.
While erosion and plate tectonics have removed evidence of how the Earth formed, the moon remains largely unchanged except for impact craters, Petro said.
“Every time we land on the moon, it establishes this understanding of a specific point, a specific location on the surface, which is very useful for testing all the models and hypotheses that we have,” he said. “This magma ocean hypothesis drives a lot of what we think about the moon, especially early in its history. The spacecraft results from the Chandrayaan-3 mission add another surface data point.”
Each mission not only adds another piece to the puzzle of understanding the moon, but also provides insights into how Earth and other rocky planets like Mars formed. Scientists’ understanding of how the moon formed guides models of how all planets, including those outside our solar system, formed and changed, Petro said.
With more missions planned to return to the Moon’s surface, it’s like the gift that keeps on giving, especially with the potential to collect samples from different regions, including the far side of the Moon and the poles.
“Every time we get a new piece of data, it’s an extra icing on the cake,” Pietro said.
