The first-ever analysis of soil from the Moon’s far side has uncovered evidence of volcanic eruptions 2.8 billion years ago, challenging long-standing beliefs about lunar activity and its timeline.
A Landmark Discovery from Chang’e 6
In June 2024, China’s Chang’e 6 probe became the first spacecraft to land on the Moon’s far side, a region shrouded in mystery and untouched by earlier missions. The South Pole-Aitken Basin, the Moon’s largest and oldest impact crater, served as the landing site. Over two days, the mission collected 4.2 pounds of lunar material using a robotic arm, gathering 108 samples of rock and soil.
Chang’e 6 then embarked on a 53-day round-trip journey, returning its precious cargo to Earth in late June. Upon arrival, researchers from the Chinese Academy of Sciences undertook a detailed analysis using advanced radioisotope dating techniques. Their findings revealed volcanic activity that lasted far longer than previously believed, pushing the boundaries of our understanding of lunar history.
Young Volcanoes in an Old Crater
The analysis uncovered volcanic basalt from 2.83 billion years ago, a remarkably “young” age for Moon rocks. Scientists were particularly surprised by the composition of these rocks, which lacked the radioactive elements typically found in volcanic material on the Moon’s near side.
University of Notre Dame professor Clive Neal noted the significance of this discovery: “The relatively young age and unique composition of these basalts challenge our existing models of how lunar magmas were formed.”
The findings also raised another intriguing question: Why does the far side of the Moon appear to have experienced volcanic activity long after such processes had ceased on the near side?
Key Findings from the Analysis
Researchers examined 180 basalt fragments from the samples:
- Most fragments dated back to 2.8 billion years ago.
- A single fragment from the collection was significantly older, forming 4.2 billion years ago.
- The data aligned across two separate studies published in Nature and Science, reinforcing the validity of these findings.
These results suggest that the Moon remained molten for far longer than previously thought, particularly on its far side.
Comparing Near and Far Sides
Scientists have long known about volcanic activity on the Moon’s near side, where large, dark plains called maria were formed by ancient lava flows. However, the far side’s terrain is distinctly different, dominated by highlands and craters with little evidence of similar lava plains.
The Chang’e 6 samples are the first to provide concrete evidence of volcanic activity on the far side, revealing a more dynamic and complex lunar history than expected.
Implications for Lunar Science
The discovery is reminiscent of the paradigm shift in lunar science sparked by the Apollo missions in the 1960s and ’70s. Those missions revealed the Moon’s history as a molten body that cooled and solidified, leaving behind its current geological features.
Now, these new findings suggest the possibility of revising that timeline. The prolonged volcanic activity indicated by the Chang’e 6 samples raises questions about the Moon’s internal heat source and how it might have varied between its near and far sides.
New Questions for Future Missions
This discovery doesn’t just rewrite a chapter of lunar history; it opens up entirely new questions:
- Why was the far side of the Moon volcanically active for longer?
- What role did differences in composition between the near and far sides play?
- Could the Moon’s internal structure hold clues to these differences?
Broader Implications for Space Exploration
The success of the Chang’e 6 mission highlights the potential for international collaboration in unraveling the Moon’s mysteries. The Chinese Academy of Sciences has committed to sharing its data and samples with scientists worldwide, fostering a global effort to better understand our closest celestial neighbor.
This discovery also underscores the importance of continued exploration. As new technologies and missions probe deeper into the Moon’s past, they could unveil insights not only about lunar geology but also about the early history of our solar system.
