GRAPES-3 and Muons — India’s Cosmic Ray Telescope

GRAPES-3 and Muons — India’s Cosmic Ray Telescope

GS Paper 3 | Science & Technology | Space Weather | Upper Atmosphere Monitoring | TIFR

Why in the News? Researchers from Mumbai (TIFR), Kochi, and Japan have developed a groundbreaking technique using 22 years of data from the GRAPES-3 telescope in Ooty. The technique enables real-time, high-accuracy monitoring of Earth’s upper atmospheric temperature and the Sun’s magnetic field — with significant implications for weather modelling and solar storm early-warning systems.

What is GRAPES-3?

Attribute	Detail
Full Name	Gamma Ray Astronomy PeV EnergieS-3
Type	NOT a conventional light-based telescope — it is a cosmic-ray tracker and muon detector
Location	Ooty (Ootacamund), Tamil Nadu
Partnership	India (TIFR Mumbai) + Japan (Osaka City University) — joint international project
Core Function	Creates a high-resolution map of invisible cosmic forces affecting Earth
Structure	16 independent modules, each containing 232 proportional counters (steel tubes)
Gas Mixture	Argon + Methane mixture inside each steel tube, with a thin tungsten wire at the centre
Data Coverage	22 years of continuous data used in the new technique

How GRAPES-3 Detects Muons — The Working Mechanism

• A muon from space passes through the outer concrete shielding layers (which filter out low-energy particles)
• The high-energy muon enters the argon-methane filled steel tube
• The muon ionises the gas molecules, releasing electrons
• Freed electrons are attracted to the central tungsten wire, generating an electrical pulse
• This pulse is recorded and processed by the telescope’s detection system
• Tubes arranged in four layers at right angles to each other allow scientists to calculate the precise path and angle of the incoming muon

Key Concepts

A. Cosmic Rays

Highly energetic subatomic particles originating from deep space that travel at speeds approaching that of light. When cosmic rays collide with particles in Earth’s upper atmosphere, they produce secondary particles — including muons.

B. What are Muons?

Property	Detail
Type	Fundamental particle — similar to an electron but approximately 207 times heavier
Origin	Secondary product of cosmic ray collisions with upper atmosphere particles
Lifespan	Extremely short — about 2.2 microseconds
Why they reach Earth	Despite short lifespan, their near-light-speed velocity causes time dilation (relativistic effect), allowing them to travel to Earth’s surface
Penetration ability	Can penetrate thick layers of concrete — which conventional particles cannot
UPSC relevance	Demonstrates application of special relativity (time dilation) in practical science

Significance and Applications

1. Upper Atmosphere Temperature Monitoring

Fluctuations in upper atmospheric temperature directly affect the number and behaviour of muons reaching Earth’s surface. The GRAPES-3 technique translates changes in muon flux into real-time temperature readings for the upper atmosphere — improving weather and climate models, particularly for stratospheric and mesospheric processes that current satellite instruments cannot directly measure with this precision.

2. Space Weather and Solar Storm Early Warning

The Sun’s magnetic field and solar storms (Coronal Mass Ejections / CMEs) alter the path and intensity of cosmic rays entering Earth’s atmosphere — and consequently the muon flux detected by GRAPES-3. This correlation makes the telescope a potential early-warning system for incoming solar storms, which can damage satellites, power grids, and communication infrastructure.

UPSC Note UPSC angle: GRAPES-3 is directly relevant to GS 3 Science & Technology. Key linkages: TIFR (Tata Institute of Fundamental Research) as a premier Indian research institution; India-Japan scientific cooperation; practical applications of cosmic ray research in atmospheric science and disaster preparedness.

Practice Question With reference to the GRAPES-3 project, consider the following statements: 1. It is an advanced radio telescope located in Ooty, Tamil Nadu, that studies light from distant galaxies. 2. It uses a mixture of argon and methane gases to detect cosmic rays and muon particles coming from space. 3. It can be used for real-time monitoring of Earth’s upper atmospheric temperature and the Sun’s magnetic field. Which of the statements given above is/are correct? (A) 1 and 2 only   (B) 2 and 3 only   (C) 1 and 3 only   (D) 1, 2 and 3 Answer: (B) 2 and 3 only — Statement 1 is incorrect: GRAPES-3 is not a radio telescope and does not study light from galaxies. It is a cosmic-ray tracker and muon detector that measures energetic particles rather than electromagnetic radiation.