The Chinese Mission Chang’e-6 brought 1,935 grams of material taken from the hidden side of the Moon to Earth. What do the new lunar champions reveal?
The visible and invisible hemisphere of the Moon show surprising discrepancies: some characteristics – such as topography, crust and volcanic history – are so divergent that so far they have left scientists perplexed.
Paradigm change. The Chinese Mission Chang’e -6, which started on May 3, 2024, revolutionized everything we knew on the Moon: over 1,935 grams of materials were taken from the South -Aitken Polo basin (Spa) in the hidden face, landing on Earth on June 25 of the same year. Spa is the largest and oldest lunar impact structure (2,500 km in diameter) and dates back to about 4.25 billion years ago. So far the effect of that impact – comparable to a thousand billion atomic bombs – on the thermal and geological development of the moon remained One of the great puzzles of planethology .
Four discoveries. In the 12 months following the arrival of the new champions, the researchers of the Chinese Academy of Sciences (IGG, NAOC), of the University of Nanchino have created a series of research published on Naturerevealing four surprising discoveries on the geological history of the hidden side of the moon.
First of all, the samples revealed that thevolcanic activity is extended over time: Two main main volcanic phases have been identified on the dark side, one dates back to 4.2 billion years ago and the other at 2.8 billion, which shows that the activity lasted at least 1.4 billion years – longer than I hypothesized so far.
Another phenomenon identified is that of floating magnetic field. Thanks to “paleomagnetic” analysis on the basaltic fragments, a surprising “rebound” of the lunar magnetic field about 2.8 billion years ago was discovered, suggesting an internal dynamo that reactivated episodically and gradually vanished. Now, since the nulce of the moon is almost completely cooled, magnetism has vanished unlike the terrestrial one which is still very hot and offers our planet a remarkable magnetic field. The Paleomagnetic analysis They study “fossil” magnetism present in the rocks. In practice, when a rock is formed (especially volcanic ones), some of its minerals align themselves with the magnetic field of the planet at that moment, as if they were small knots. By analyzing these alignments, scientists can reconstruct the history of the magnetic field of a celestial body (such as the moon or the earth), also going up to billions of years ago.
In addition, the analyzes revealed that the cloak of the hidden side contains less water than that of the visible side, confirming an uniform distribution of volatile elements inside our satellite.
For “volatile elements” We mean chemicals that tend to evaporate easily or remain in a gaseous form at low temperatures. In planetary geology, these include: water (H₂O), carbon dioxide (CO₂), Zolfo (S), Fluoro (F), Chlorine (CL), hydrogen (H) and noble gases such as Elio or Argon. These elements are important because they influence the formation of rocks, volcanic activity, the evolution of the atmosphere (where present) and the thermal history of a celestial body.
Finally, the basalts analyzed show evidence of a strongly impoverished source of the cloak, underlining the central role of impacts in modeling the lunar depths. A depleted cloak It is a portion of the cloak (the part of the moon or earth under the crust) that has lost some of its original chemical elements, in particular those who tend to concentrate in magma, such as rare elements of the earth (ree), titanium (ti), aluminum (al) and other so -called “incompatible” elements (that is, they prefer to be in magma rather than in solid crystals). The impoverishment occurs when the cloak undergoes a partial merger: part of the material merges and form magma, which then dates back and solidifies on the surface as a volcanic rock. What remains below, after the extraction of magma, is the “impoverished” cloak, that is, without a part of its more fertile elements.
Global implications. These discoveries not only concern the history of the hidden face of the moon, but represent a crucial step in the understanding of the formation and evolution of the whole planets. They reveal the importance of cataclysmic impacts, the internal evolution of our satellite and the structural differences between the lunar hemispheres. The Chang’e -6 mission therefore, it is affirmed as a milestone in lunar exploration.
