International Space Agencies – Missions and Discoveries

Chang’e-4 Mission


From UPSC perspective, the following things are important :

Prelims level : About the mission

Mains level : Magma Ocean Theory and formation of Moon


  • In January, the Chinese spacecraft Chang’e-4 — named after the moon goddess in Chinese mythology — became the first ever craft to touch down on the far side of the lunar surface.
  • The team landed its probe in the Von Karmen Crater in the Aitken Basin at the Moon’s south pole — home to one of the largest impact craters known in the solar system.
  • Scientists have said they could be a step closer to solving the riddle behind the Moon’s formation, unveiling the most detailed survey yet of the far side of Earth’s satellite.

Formation of Moon

  • The moon is believed to have gone through a phase during its formation when it was partially or entirely composed of molten rock.
  • As it cooled, denser minerals sank to the bottom of the magma-ocean, while lighter materials gathered near the surface to form its mantle.
  • They detected materials such as olivine and low-calcium pyroxene that are rare elsewhere on the surface.
  • These materials were ejected from the Moon’s upper mantle when it was struck by a meteor.

Lunar Magma Ocean Theory

  • The lunar magma ocean (LMO) is a term used in planetary science to describe the thermal state of Earth’s Moon in the thousands to millions of years following its formation.
  • The most widely accepted model for the formation of the Moon invokes a collision between proto-Earth and another proto-planet.
  • The Moon accreted from the resulting debris disk surrounding the Earth, which likely consisted of molten and vaporized silicate material.
  • The accretion of the Moon from this debris disk leads to a body in a largely or completely molten state.
  • This “magmasphere” is referred to as the LMO.
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