ISRO Missions and Discoveries

Indian meteorite helps study Earth’s formation

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Olivine, Bridgmanite

Mains level : Formation of Earth

The researchers from the Geological Survey of India collected about 30 meteorite fragments with the largest weighing around a kilogram near the town of Katol in Nagpur in 2012.

Significance of meteor study

  • Now, by studying the composition of these meteorite fragments, researchers have unraveled the composition expected to be present in the Earth’s lower mantle which is at about 660 km deep.
  • Studying the meteorite could also tell us more about how our Earth evolved from being a magma ocean to a rocky planet.

Key component of the Meteor: Olivine

  • Initial studies revealed that the host rock was mainly composed of olivine, an olive-green mineral.
  • Olivine is the most abundant phase in our Earth’s upper mantle.
  • Our Earth is composed of different layers including the outer crust, followed by the mantle and then the inner core.

How to study a meteorite?

  • The researchers took a small sample of the meteorite and examined it using special microscopy techniques.
  • The mineralogy was determined using a laser micro-Raman spectrometer.
  • These techniques helped the team identify, characterise the crystal structure of the meteorite and determine its chemical composition and texture.

What does the new study show?

  • The international team of scientists examined a section of this highly-shocked meteorite. It resembles to the first natural occurrence of a mineral called bridgmanite.
  • The mineral was named in 2014 after Prof. Percy W. Bridgman, recipient of the 1946 Nobel Prize in Physics.
  • Various computational and experimental studies have shown that about 80% of the Earth’s lower mantle is made up of bridgmanite.
  • By studying this meteorite sample, scientists can decode how bridgmanite crystallized during the final stages of our Earth’s formation.

Bridgmanite: On Earth vs. on Meteorite

  • Katol meteorite is a unique sample and it is a significant discovery.
  • The bridgmanite in the meteorite was found to be formed at pressures of about 23 to 25 gigapascals generated by the shock event.
  • The high temperature and pressure in our Earth’s interior have changed over billions of years causing crystallisation, melting, remelting of the different minerals before they reached their current state.
  • It is important to study these individual minerals to get a thorough idea of how and when the Earth’s layers formed.

How does it help understand evolution of Earth?

  • The inner planets or terrestrial planets or rocky planets Mercury, Venus, Earth, and Mars are formed by accretion or by rocky pieces coming together.
  • They were formed as a planet by increased pressure and high temperature caused by radioactive elements and gravitational forces.
  • Our Earth was an ocean of magma before the elements crystallised and stabilised and the different layers such as core, mantle were formed.
  • The heavier elements like iron went to the core while the lighter silicates stayed in the mantle.
  • By using the meteorite as an analog for Earth, we can unearth more details about the formation.

Answer this question from our AWE initiative:

What are seismic waves? How have they helped in understanding the structure of the earth? (250 W/ 15 M)

 

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