MAINS Current Affairs includes Failure of Atomic Clock Cripples ISRO’s NavIC & Thorium Can Power India’s 100 GWe by 2047 Mission

Science & Technology

1. Failure of Atomic Clock Cripples ISRO’s NavIC

Context: India’s indigenous navigation system NavIC has faced a setback after the failure of IRNSS-1F satellite due to malfunction of its last operational rubidium atomic clock.

The satellite, launched in 2016 by the Indian Space Research Organisation, has already completed its 10-year design life, making the failure partly expected but still significant for system reliability.

What is an Atomic Clock?

An atomic clock is an ultra-precise timekeeping device that measures time using the natural vibration frequency of atoms, typically cesium atoms and rubidium atoms.

Working Principle

• Atoms emit radiation at highly stable and predictable frequencies when transitioning between energy levels.
• The clock measures this frequency and converts it into standard time signals.

Key Features

• Extremely accurate (precision up to nanoseconds)
• Essential for:
  • satellite navigation
  • telecommunications
  • defence systems
  • scientific research

About NavIC (Navigation with Indian Constellation)

• NavIC (earlier called Indian Regional Navigation Satellite System – IRNSS) is India’s independent regional navigation system developed by ISRO.
• Operational since 2013
• Designed for both civilian and military purposes

Coverage Area

• Provides navigation services across India and up to 1,500 km beyond its borders.

Satellite Constellation

• Total 7 satellites:
  • 3 in Geostationary Orbit (GEO)
  • 4 in Inclined Geosynchronous Orbit (IGSO)
• Supported by a network of ground control stations operating 24×7.

Services Offered

Standard Position Service (SPS)

• For civilian users
• Provides navigation and timing services.

Restricted Service (RS)

• For strategic and military users
• Offers encrypted and more accurate signals.

Accuracy

• Position accuracy: Better than 20 meters
• Timing accuracy: Better than 40 nanoseconds

Impact of Atomic Clock Failure

Disruption in Timing Accuracy

Atomic clocks are the core component of navigation satellites. Their failure directly affects:

• Precise timing signals
• Synchronization of satellite constellation

Reduced Navigation Reliability

• Failure of IRNSS-1F reduces overall redundancy in the NavIC system.
• May impact accuracy and reliability of positioning services.

Broader Challenges in NavIC System

Limited Satellite Redundancy

• With only 7 satellites, failure of even one satellite can significantly impact system performance.

Atomic Clock Reliability Issues

• Past NavIC satellites have also faced rubidium clock failures, indicating reliability concerns.

Dependence on Indigenous Technology

• While self-reliance is a strength, developing highly reliable atomic clocks remains technologically challenging.

Way Forward

Satellite Replacement and Upgradation

• Launch of next-generation NavIC satellites (NVS series) with improved atomic clocks.

Improved Clock Technology

• Development of more robust atomic clocks with longer operational life.

Strengthening Redundancy

• Increasing the number of satellites to ensure backup support and continuous service.

Integration with Global Systems

• Enhancing compatibility with global navigation systems for better accuracy and resilience.

Conclusion

The failure of the atomic clock in IRNSS-1F highlights the critical role of precise timing in satellite navigation systems. While NavIC represents a major step toward technological self-reliance and strategic autonomy, strengthening system reliability, redundancy, and advanced clock technology will be essential to ensure its long-term effectiveness.

Energy

2. Thorium Can Power India’s 100 GWe by 2047 Mission

Context: The SHANTI Act 2025 marks a significant step in India’s nuclear energy roadmap. However, fully realising the potential of thorium-based energy remains critical for achieving India’s target of 100 GWe nuclear capacity by 2047.

India’s Thorium Resource Advantage

Abundant Reserves

India possesses one of the largest thorium reserves globally, mainly found in:

• Coastal sands of Kerala
• Coastal and riverine deposits in Odisha

Together, these regions account for over 70% of India’s thorium resources.

Key Challenge

• Extraction of thorium from ores is energy-intensive.
• Generates significant radioactive waste.
• Requires advanced and costly technology for utilisation.

Why Thorium is Crucial for India

Reducing Dependence on Uranium Imports

• India’s nuclear programme currently relies heavily on imported uranium.
• Domestic uranium reserves are low-grade and expensive to extract.

Thorium offers a domestic and secure alternative fuel source.

Global Uranium Constraints

• Current global nuclear capacity: ~380 GWe
• Expected by future: ~1400 GWe

At this scale, global uranium reserves (~8 million tonnes) may last only about 30 years under once-through usage.

This makes thorium a long-term sustainable option.

Strategic Importance

• Aligns with India’s goal of energy security and self-reliance.
• Supports low-carbon energy transition.
• Fits into India’s long-term nuclear vision.

Nuclear Characteristics of Thorium

• Thorium (Th-232) is not fissile but fertile.
• It absorbs neutrons and converts into Uranium-233 (U-233).
• U-233 then acts as a fissile fuel for nuclear reactions.

India’s Three-Stage Nuclear Programme

• India’s nuclear strategy, conceptualised by Homi J. Bhabha, is designed to utilise limited uranium and abundant thorium efficiently.

Stage 1: Pressurised Heavy Water Reactors (PHWRs)

• Fuel: Natural uranium (U-238)
• Moderator: Heavy water (D₂O)
• Objective: Produce Plutonium-239 (Pu-239) as a by-product.

Stage 2: Fast Breeder Reactors (FBRs)

• Fuel: Pu-239 + U-238
• Key Feature: Produces more fissile material than consumed.
• Output:
  • Energy
  • More Pu-239
  • Uranium-233 (U-233)

Stage 3: Thorium-Based Reactors (AHWRs)

• Reactor Type: Advanced Heavy Water Reactor (AHWR)
• Fuel: Thorium (Th-232) + Pu-239
• Output:
  • Energy
  • Uranium-233 (reusable fuel)

This stage aims to fully utilise India’s vast thorium reserves.

Significance of Thorium for India

Resource Advantage

• India has limited uranium but abundant thorium, giving it a unique long-term advantage.

Energy Security

• Reduces dependence on imported nuclear fuel.
• Enhances strategic autonomy in energy.

Environmental Benefits

• Thorium reactors produce:
  • less long-lived radioactive waste
  • improved safety characteristics compared to traditional reactors.

Long-Term Sustainability

• Supports India’s clean energy goals and net-zero commitments.
• Ensures fuel availability for centuries.

Challenges in Thorium Utilisation

Technological Constraints

• Thorium reactors require advanced reactor designs (AHWRs).
• Technology is still in development and testing stages.

Economic Viability

• High initial investment costs.
• Limited commercial-scale deployment globally.

Fuel Cycle Complexity

• Conversion of thorium to U-233 involves complex reprocessing technologies.
• Handling U-233 requires stringent safety protocols.

Infrastructure Gaps

• Need for:
  • specialised reactors
  • fuel fabrication facilities
  • reprocessing infrastructure.

Way Forward

Accelerate R&D

• Strengthen research at institutions like Bhabha Atomic Research Centre.

Fast-Track AHWR Deployment

• Move from pilot projects to commercial-scale thorium reactors.

Strengthen Policy Support

• Effective implementation of reforms under the SHANTI Act 2025.

Public-Private Participation

• Encourage innovation and investment in nuclear technology.

Conclusion

Thorium holds the key to India’s long-term nuclear energy independence. While challenges remain in technology and economics, successful deployment of thorium-based reactors can enable India to achieve its ambitious target of 100 GWe nuclear capacity by 2047, ensuring clean, secure, and sustainable energy for the future.

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