Far Side of the Moon Had Volcanic Eruptions for Over One Billion Years
Scientists have uncovered stunning revelations about the Moon, particularly its far side, which remained shrouded in mystery and intrigue for millennia. A team led by Professor Xu Yigang from the Guangzhou Institute of Geochemistry has been delving deep, not just metaphorically, but literally, as they examined lunar soil samples taken from the Moon's South Pole-Aitken (SPA) Basin. Thanks to these samples, collected by China's Chang’e-6 mission, researchers have revealed the far side of the Moon had volcanic activity spanning over one billion years.
This research sheds light on intriguing questions surrounding the Moon's geological history, especially considering its two distinct sides. The near side of the Moon, which we see from Earth, features dark areas known as maria, remnants of ancient volcanic eruptions. These large basaltic plains were formed from molten lava, which cooled to create the familiar surface we recognize. Conversely, the far side—often called the dark side, though it receives sunlight just as the near side does—holds less than 2% of these basaltic plains, compared to about 30% on the near side.
The surprise discovery of different types of mare basalts by Xu's team is significant. They identified two key types: low-Ti and very low-Ti (VLT) basalts, which help paint the far side's geological story. Professor Xu stated, "The samples returned by Chang’e-6 provide the best opportunity to investigate the lunar global dichotomy." Using high-precision Pb-Pb dating techniques, they traced the low-Ti basalt samples to origins dating back to around 2.83 billion years, reflecting notable volcanic activity during this period.
But what about the Moon's original volcanic timeline? A different team, led by Professor Li Qiuli, focused on radioisotope dating of 108 basalt fragments. Astonishingly, 107 of these fragments, dating back to 2.807 billion years ago, signified prolonged eruptions. Among them, one fragment—a high-aluminum basalt—was pinpointed to be about 4.203 billion years old. This makes it the oldest lunar basalt for which age has been precisely determined, raising questions about the very nature of volcanic activity on the Moon’s far side.
The implications of these findings extend beyond mere geological curiosity. For starters, they invite us to rethink existing lunar crater chronology models. Christopher Hamilton, an independent expert specializing in planetary volcanoes, highlighted the importance of samples from previously uncharted territory. The results could help recalibrate our understandings of how impacts on the lunar surface have shifted throughout the ages, offering glimpses at broader patterns of cosmic activity.
Interestingly, the new data suggests there’s been a steady impact flux on the Moon since 2.83 billion years ago, affording insights not just about our lunar neighbor, but also the dynamics of planet migration within the early Solar System. Essentially, exploring the Moon is like holding up a mirror to our own cosmic neighborhood.
The Chang’e-6 mission, which took off on May 3, 2024, aimed to grab about four pounds (around 2 kg) of rocks from the far side—an endeavor unprecedented until now. The spacecraft landed successfully and collected surface samples with precision techniques, including using both drills and scoops—one going as deep as two meters. After securing the samples, the lander’s ascent vehicle rocketed back to join the orbiter above and eventually returned to Earth, landing in Inner Mongolia approximately six weeks later.
With such groundbreaking results now on the table, the question remains: What does the future of lunar exploration hold? Professor Xu and his team have expressed optimism, believing there's still much more to untangle about the Moon. The Chang’e-6 has opened the doors to even greater possibilities for lunar exploration and research.
Interestingly, support for this venture has poured in from various institutes, including the Chinese Academy of Sciences and the National Natural Science Foundation of China, which enhances the prospects for future lunar missions. With each new mission, tantalizing discoveries are likely to emerge, driving our quest for knowledge about this celestial body, which, though so familiar to us, continues to hide countless secrets waiting to be explored.
Published studies documenting these findings have appeared not only in Nature but also Science, indicating the broader impact of these discoveries within the scientific community. The excitement surrounding this topic isn't likely to fade soon.
Through these explorations, humanity pushes the boundaries of what we know not just about the Moon, but about our broader universe. Reminders of how much remains to be discovered about our own cosmic neighborhood emerge with every lunar mission. The Moon, with its silence and stillness, still holds stories eager to be unveiled.
