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Square Kilometer Array Observatory


Scientists in India will now also be part of the international mega-science project, the Square Kilometer Array Observatory (SKAO), that will function as the world’s largest radio telescope. India’s Giant Metrewave Radio Telescope (GMRT) is amongst the world’s six large telescopes.


GS III: Science and Technology

Dimensions of the Article:

  1. Radio Telescopes
  2. Square Kilometer Array Observatory (SKAO): Overview and India’s Role
  3. Giant Metrewave Radio Telescope (GMRT)
  4. Gravitational Waves

Radio Telescopes:

Detection of Radio Waves:

  • Radio telescopes are instruments designed to detect and amplify radio waves emanating from space, converting them into signals for astronomers to decipher.

Universal Observations through Light Waves:

  • Astronomy involves observing various waves of light.
  • Stars, galaxies, and celestial objects emit visible light as well as electromagnetic waves like radio waves, gamma rays, X-rays, and infrared radiation.

Components of a Radio Telescope:

  • A basic radio telescope consists of three essential components:
    • One or more antennas pointed towards the sky to gather radio waves.
    • A receiver and amplifier to strengthen the weak radio signals to measurable levels.
    • A recorder to document and preserve the received signals.

Versatility of Radio Telescopes:

  • Radio telescopes are operational both day and night, providing astronomers with continuous opportunities for observation.

Square Kilometer Array Observatory (SKAO): Overview and India’s Role

  • The Square Kilometer Array is an international radio telescope project situated in Australia and South Africa.
  • Its construction in the southern hemisphere is chosen for the optimal view of the Milky Way galaxy and minimal radio interference.
  • Participating countries include the UK, Australia, South Africa, Canada, China, France, India, Italy, and Germany.


  • Aims to construct and operate cutting-edge radio telescopes to revolutionize our understanding of the Universe, fostering global collaboration and innovation.

Construction Phases:

  • The project has two construction phases: SKA1 (current) and a potential future phase known as SKA2.
  • Construction began in December 2022 in both South Africa and Australia.


  • Jodrell Bank Observatory, United Kingdom.
India’s Role:
  • India, through the National Centre for Radio Astrophysics (NCRA) and other institutions, has been involved in SKAO’s development since the 1990s.
  • India’s primary contribution is in developing and operating the Telescope Manager element, the crucial software enabling the telescope’s functionality.
    • NCRA led an international team from nine institutions and seven countries in this software development.
  • Countries must sign and ratify the SKAO convention to formalize their membership.
  • Recently, the Central Government of India decided to join the project, allocating a financial sanction of Rs 1,250 crore.

Giant Metrewave Radio Telescope (GMRT)

  • GMRT is a low-frequency radio telescope used for investigating various radio astrophysical phenomena, ranging from nearby solar systems to the edge of the observable universe.
  • It is located at Khodad, situated 80 km north of Pune, and is operated by the National Centre of Radio Astrophysics (NCRA).
  • The NCRA is a part of the Tata Institute of Fundamental Research (TIFR) based in Mumbai.
  • GMRT is a project of the Department of Atomic Energy (DAE) and operates under the Tata Institute of Fundamental Research (TIFR).
  • The telescope consists of 30 fully-steerable dish-type antennas, each with a diameter of 45 meters, spread over a 25-km region.
  • Presently, GMRT holds the distinction of being the world’s largest radio telescope operating at meter wavelengths.
The objectives of GMRT include:

Detecting highly redshifted spectral lines of neutral Hydrogen:

  • GMRT aims to detect the faint signals of neutral Hydrogen in its highly redshifted state.
  • This can provide insights into the early phase of the Universe when proto-clusters or protogalaxies were forming before condensing into galaxies.
  • Redshift, in this context, refers to the change in the wavelength of the signal based on the object’s location and movement.

Studying rapidly-rotating Pulsars in our galaxy:

  • GMRT is also used to search for and study pulsars, which are rapidly rotating neutron stars with extremely high densities.
  • Pulsars emit regular radio beams that flash towards the Earth, similar to how a lighthouse emits beams.
  • By studying pulsars, scientists can gain valuable information about their properties, behavior, and the surrounding environment.

Significance of GMRT

The significance of GMRT lies in its unique capabilities and contributions to various fields of astrophysics. Some key points highlighting its significance are:

Wide frequency bandwidth:

  • GMRT operates within the frequency range of 100 MHz to 1,500 MHz, allowing it to observe a broad range of radio emissions and signals from celestial objects.
  • This wide frequency coverage enables the study of diverse astrophysical phenomena.

International collaboration:

  • GMRT is highly sought-after by scientists from more than 30 countries, demonstrating its recognition and importance in the global scientific community.
  • Its capabilities and data are valuable for researchers worldwide.

Tracing the evolution of galaxies:

  • GMRT plays a crucial role in understanding the evolution of galaxies over cosmic time.
  • By detecting and analyzing the radio emissions from atomic hydrogen (21 cm wavelength), GMRT enables scientists to trace the distribution and behavior of neutral gas in galaxies.
  • This gas is essential for star formation and provides insights into the processes involved in galaxy evolution.

Studying distant galaxies:

  • GMRT’s large collecting area and sensitivity allow for the detection of faint radio signals emitted by distant galaxies.
  • This is particularly important when studying the 21 cm emission from atomic hydrogen in distant galaxies, which is otherwise challenging to detect.
  • GMRT’s data contributes to our understanding of galaxies across different cosmological periods.

Wide range of astrophysical studies:

  • GMRT’s capabilities extend beyond galaxy evolution.
  • Its large collecting area and frequency coverage make it a useful instrument for studying various astrophysical phenomena.
  • This includes investigating solar and planetary radio emissions, studying the relationship between solar activity and disturbances in the interplanetary medium, and exploring other frontier areas of astrophysics.

Gravitational Waves

  • Gravitational waves are space-time ripples resulting from violent and energetic processes in the Universe.
  • Albert Einstein predicted their existence in 1916 through his general theory of relativity.
  • According to Einstein’s mathematics, massive accelerating objects, such as orbiting black holes or neutron stars, disrupt space-time, causing undulating waves to propagate in all directions.
  • These waves carry information about their origins and provide insights into the nature of gravity.
  • Massive objects like neutron stars or black holes orbiting each other are sources of gravitational waves.
Production of Gravitational Waves
  • Cataclysmic events, including colliding black holes, supernovae, and colliding neutron stars, generate the strongest gravitational waves.
  • Gravitational waves can also be produced by non-spherical rotating neutron stars and possibly remnants of gravitational radiation from the Big Bang.
  • Gravitational waves are challenging to detect due to their weak interaction with matter.
  • Interferometers, highly sensitive instruments, have been developed to detect these waves.
  • The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a well-known example that achieved the first direct detection of gravitational waves in 2015.

-Source: The Hindu, Indian Express


April 2024