While the moon might now seem like a cold, dusty, desert, new evidence from India’s Chandrayaan-3 mission has revealed this was not always the case.
Analysis of the lunar surface shows that the moon’s south pole was once completely covered by an ocean of molten magma.
When Chandrayaan-3 landed near the moon’s south pole in August last year, India’s space agency gathered 23 measurements of a never-before-studied region.
Their measurements discovered a uniform layer of ferroan anorthosite, a white rock believed to have floated to the surface of the molten rock during the moon’s formation.
This supports the ‘Lunar Magma Ocean’ (LMO) theory which claims the whole of the moon’s surface was formed from a cooling layer of magma that formed 4.5 billion years ago.
New analysis of data from Indian’s Chandrayaan-3 mission has revealed the moon was once covered in an ocean of molten lava (pictured: artist’s impression)
The LMO theory is not new – it dates back to the 1970s – but the new findings now bolster the theory with evidence of molten rock at another region of the moon (its south pole).
On August 23, 2023, the Vikram lander successfully touched down on a region of the moon’s south pole as part of the Chandrayaan-3 mission.
Vikram’s landing site, at about 70 degrees south, was the furthest south any landing craft had ever been.
Over 10 days, Vikram’s smaller Pragyaan rover travelled over the lunar landscape, constantly recording and transmitting data back to Earth.
That data included 23 measurements from a device called the alpha particle X-ray spectrometer.
This lightweight instrument used a radioactive source to bombard the lunar surface with radiation, exciting the atoms in the ground, and measuring the energy they release.
By recording that emitted energy, researchers have been able to calculate the mineral composition of the lunar soil.
After landing in August last year at a site near the Moon’s south pole (illustrated in yellow) the Vikram lander deployed a rover which collected data about the moon’s mineral composition
That analysis revealed that the area around the Chandrayaan-3 landing site was relatively uniform and composed largely of ferroan anorthosite.
The researchers also found that the mineral composition at the Chandrayaan-3 site was similar to that found by NASA’s Apollo 16 and the Soviet Luna-20 mission.
What is unusual about that finding is that those two landing sites are both in the moon’s equatorial region, a long way away from where Chandrayaan-3 touched down.
The fact that these three distant sites all have roughly the same material composition suggests that they might have all come from the same lunar magma ocean.
The moon is believed to have been formed 4.5 billion years ago when a Mars-sized planet collided with Earth and knocked a chunk of material out into space.
As that material coalesced, the intense energies involved melted the rocks into a vast ocean of magma which covered the entire moon.
As the surface cooled over tens to hundreds of millions of years, the cooler ferroan anorthosite rose to the surface while heavier minerals like olivine and pyroxene sank deep below to form the moon’s mantle.
The current lunar highlands are believed to be what remains of this ancient crust after billions of years.
The Pragyaan (pictured) found that the area around the landing site was uniform and made of ferroan anorthosite, a white rock believed to have formed the ancient moon’s crust
Experts believe the moon was formed when a Mars-sized planet called Theia collided with the Earth and knocked material out into space
The data collected by Chandrayaan-3 (pictured) suggests that the moon was once covered by an ocean of lava. As it cooled the lighter ferroan anorthosite rose to the surface and formed the ancient crust
Co-author of the paper Dr Santosh Vadawale from the Physical Research Laboratory, told the BBC: ‘The theory of early evolution of the moon becomes much more robust in the light of our observation.’
Alpha particle x-ray data also provides evidence for an enormous meteor strike near the lunar south pole.
The data gathered by the rover showed that the area around the landing site was much higher in magnesium than would have been expected for pure ferroan anorthosite.
In their paper, published in Nature, the researchers argue that this material could have been blasted out of the ground by a huge impact which excavated the magnesium-rich materials deep in the mantle.
The researchers believe that magnesium in the soil was deposited by the same impact which formed the South Pole-Aitken basin over 217 miles (350 km) away. This magnesium was then further mixed into the area by impacts like the Schomberger crater (impact illustrated)
This impact could have been the same meteor strike which formed the 1,600-mile (2,500km) wide South Pole-Aitken basin over 217 miles (350 km) away from the Chandrayaan-3 landing site.
The mineral findings are consistent with the idea that magnesium-rich rocks were scattered over the site before being mixed by further meteor impacts.
These findings are also important to the future of India’s space research because they provide a basis for future observations.
Previously, the Indian space agency had made observations of the lunar surface from orbit on Chandryaan-1 and 2.
However, without measurements from the ground, interpreting those observations required some scientific guess work.
Beautiful: Image provided by the Indian Space Research Organisation (ISRO) taken by the Pragyan rover shows the Vikram lander. Photo released on August 30, 2023
This new data taken directly from the lunar surface provides researchers with a ‘ground truth’ against which they can compare future orbital observations.
This could help the space agency narrow down their search for water which would be a huge support for any future effort to establish a future crewed base.
India plans to launch another lunar mission in 2025 or 2026 which aims to collect material and return it to Earth for analysis.
