More Metallic Moon: NASA

• 06 Jul 2020

Why in News

Recently, the National Aeronautics and Space Administration (NASA) has found evidence of greater quantities of metals such as iron and titanium on the Moon’s subsurface.

• The metallic distribution was observed by the Miniature Radio Frequency (Mini-RF) instrument aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft.

Lunar Reconnaissance Orbiter

• It is a NASA moon mission that has been in operation since 2009.
• The mission particularly focuses on the moon's poles to search for water or ice that could exist in permanently shadowed craters.

Miniature Radio Frequency Instrument

• It is one of the two radar instruments launched to the moon to map the lunar poles, search for water and ice and to demonstrate future NASA communication technologies, under the Mini-RF project.
  
  • The first instrument, launched on the Indian Space Research Organisation (ISRO) Chandrayaan-1 spacecraft, mapped both polar regions of the Moon.
  • The second instrument, currently flying on NASA’s LRO, has been mapping the different geologic units of the lunar surface.

Key Points

• The LRO’s Mini-RF instrument was measuring dielectric constant within lunar soil in crater floors in the Moon’s northern hemisphere.
  
  • Dielectric constant, an electrical property, is the ratio of the electric permeability of a material to the electric permeability of a vacuum.
  • Dielectric properties are directly linked to the concentration of metal minerals.
• The level of this property increased while surveying larger craters and kept rising in crater sizes up to 5 km in diameter. Beyond that size, the value of the dielectric constant leveled off.
• It raised the possibility that the dielectric constant increased in larger craters because the meteors that created them dug up dust containing iron and titanium oxides from beneath the Moon’s surface.
• The Mini-RF findings were backed by metal oxide maps from the LRO Wide-Angle Camera, Japan’s Kaguya mission and NASA’s Lunar Prospector spacecraft, which showed that larger craters with their increased dielectric material were also richer in metals.
  
  • The metal oxide maps suggested that more quantities of iron and titanium oxides were dug up from 0.5 to 2 km below the Moon’s surface as compared from the first 0.2 to 0.5 km.
• Significance:
  
  • If the findings are proven to be true, it would imply that there are large quantities of iron and titanium oxides beyond a few meters of the Moon’s upper surface.
  • The finding could aid in drawing a clearer connection between Earth and the Moon.
• NASA has now undertaken further research to find whether the same relation between metal deposits and crater size holds true on the southern hemisphere of the Moon.

Connection with Moon Formation

• A Mars-sized protoplanet collided with the newly formed Earth around 4.5 billion years ago, breaking off its piece that went on to become a satellite.
• The hypothesis is backed by substantial evidence, such as the close resemblance between the Moon’s bulk chemical composition with that of Earth.
• However, scientists have been trying to explain how Earth’s crust has fewer amounts of iron oxide than the Moon. Now, the new discovery of even greater quantities of metal on the Moon makes the process more difficult.
• A possible reason could be that the Moon was created from a material much deeper beneath Earth’s surface than was believed before, or that the newly found metal presence could be the result of molten lunar surface cooling down gradually.

Source: IE