Context

Astronomers propose to place high-resolution telescopes on the moon’s surface and its orbit which includes the Pratush Radio Telescope from India.

• Objective: To study the Cosmic Dawn and Epoch of Reionization and spot signals from the Dark Ages (which would be essentially free from the influence of any starlight).

Why Renewed Push for Moon Based Telescopes? 

• Limitations of Earth Based Telescopes: 

  • Atmospheric disturbances: Optical telescopes (collect visible light at longer wavelengths) have to peer through layers of the planet’s atmosphere which makes it increasingly difficult for optical instruments to see through the polluted skies.
    • Electromagnetic interference: Radio telescopes (collect radio waves with the shortest wavelengths) have to contend with earth based Radio Frequency interference from the communications channels used by radar systems, aircraft, and satellites,  adding to the cacophony of the electromagnetic ‘hiss’.
    • Earth’s  ionosphere also  blocks radio waves coming from outer space.
    • Earth orbiting telescopes: They receive radio noise from the planet along with the signals from outer space. 

• Advantages of Lunar Surface for Observation: 

• • Radio -quiet location: Moon provides a pristine and airless desolation to the optical telescopes for crystal-clear viewing conditions throughout the lunar night lasting for  two weeks at a time.
  • No earth based RFI:  Radio telescopes on the lunar far side will be protected by  the moon itself as it will block  out the  radio transmissions from the earth and electrically charged plasma winds blowing from the Sun.

PRATUSH (Probing ReionizATion of the Universe using Signal from Hydrogen)

• About: Pratush Radio Telescope is a future radiometer in lunar orbit.
• Built by: The Raman Research Institute (RRI) in Bengaluru with active collaboration from the Indian Space Research Organisation (ISRO).
• Payloads: Pratush Radio Telescope will carry a wideband frequency-independent antenna, a self-calibrating analog receiver and a digital correlator
• Placed at: Initially will be placed around earth orbit and after some fine-tuning, ISRO will be placed into moon’s orbit.

• Objective: To reveal the Cosmic Dawn of our Universe and answer the question of when the first stars formed in our universe, the nature of the first stars, the color of the light of Cosmic Dawn and  will inform us of the first rays of the first suns in the infant universe.

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