1. DRDO’s Major Leap: India Advances in Hypersonic Propulsion Technology

Context: The Defence Research and Development Laboratory (DRDL), a key unit of DRDO, has successfully completed ground testing of an Active-Cooled Scramjet Subscale Combustor.

The test, conducted for over 1000 seconds, marks a significant achievement towards developing indigenous hypersonic weapon technology in India.

Understanding Hypersonic Propulsion Technology:

Hypersonic propulsion is a cutting-edge domain focused on enabling vehicles to travel at speeds exceeding Mach 5 (five times the speed of sound).

Applications:

• Hypersonic cruise missiles
• Advanced aerospace systems

What is a Mach Number?

A Mach number represents the ratio of the object’s speed to the speed of sound. For instance, Mach 5 means five times faster than the speed of sound.

Key Features of Hypersonic Propulsion:

Air-Breathing Engines:

Hypersonic vehicles employ Scramjet Engines (Supersonic Combustion Ramjet) which breathe atmospheric oxygen for combustion, eliminating the need to carry onboard oxidizers.
This significantly enhances the efficiency and range of hypersonic vehicles.

Scramjet Engine: The Core of Hypersonic Flight

What is a Scramjet?

A Scramjet is a type of air-breathing engine designed to operate efficiently at hypersonic speeds. Unlike conventional engines, it allows supersonic combustion of incoming air.

Key Differences: Scramjet vs Ramjet

• Ramjet: Slows down incoming air to subsonic speeds before combustion.
• Scramjet: Maintains supersonic airflow throughout the combustion process, enabling much higher speeds.

Working Principle:

• Utilizes the vehicle’s forward motion to compress incoming air without using any rotating compressors.

India is now the fourth country — after the USA, Russia, and China — to successfully demonstrate flight testing of a Scramjet engine.

Importance of the Latest Scramjet Test:

Validation of Long-Duration Supersonic Combustion:

• The successful 1000-second test confirms the design reliability and efficiency of India’s scramjet technology.

• It builds upon the earlier 120-second test held in January, showcasing continuous progress.

Boost to India’s Hypersonic Missile Program:

• Scramjet engines enable air-breathing propulsion, reducing dependency on onboard oxidizers and significantly enhancing missile range and payload capacity.
• This successful test lays the groundwork for full-scale flight testing of hypersonic cruise missiles in the near future.

2. Overseas Remittances by Indians under LRS Drop by 29%

Context: Overseas remittances by Indian residents under the Liberalised Remittance Scheme (LRS) of the Reserve Bank of India (RBI) declined by 29% to $1,964.21 million in February 2025, compared to $2,768.89 million in January 2025.

What is the Liberalised Remittance Scheme (LRS)?

• LRS is part of the Foreign Exchange Management Act (FEMA), 1999, which governs outward remittances from India.
• Under LRS, resident individuals, including minors, can freely remit up to $250,000 per financial year for permissible current or capital account transactions.
• Permitted purposes include:
  • Education abroad
  • Medical treatment overseas
  • Purchase of property
  • Investment in foreign stocks

Recent Update:

The Union Budget 2025 raised the threshold for collecting Tax Collected at Source (TCS) on LRS transactions from 7 lakh to 10 lakh.

This move is expected to boost outbound tourism, foreign education, and airline sectors by reducing upfront tax burdens.

Reasons Behind the Decline:

1. Drop in Indian Students Abroad:

• A sharp decline of at least 25% was recorded in the number of Indian students receiving study permits in Canada, the United States, and the United Kingdom during 2024.

2. Volatile Global Economy:

• Economic and market volatility led many individuals to postpone or cancel their travel and investment plans.

Understanding Remittances:

What are Remittances?

• Remittances refer to the electronic transfer of money to individuals, often family members, residing in another country.
• Typically sent by those employed in blue-collar or skilled jobs overseas.

Why are Remittances Important?

• They provide a significant source of income for many countries.
• Help stabilize economies, support local consumption, and even finance national trade deficits.

Modes of Remittance Transfer:

• Banks
• Money Transfer Operators
• Digital Platforms

Types of Remittances:

India’s Remittance Landscape:

Overall Growth:

• India’s remittances more than doubled, rising from $55.6 billion in 2010-11 to $118.7 billion in 2023-24 — a trickle turning into a flood.

Contribution by Countries:

• United States and United Kingdom: Together accounted for 40% of India’s inward remittances in FY24, up from 26% in FY17.
• United States: Emerged as the top source, contributing nearly 28% in FY24.
• United Arab Emirates (UAE): Still the second-largest contributor with 19.2%, driven mainly by Indian migrants in construction, healthcare, hospitality, and tourism sectors.
• Singapore: Saw an increase in its share to 6.6% in FY24, the highest since FY17.

State-wise Distribution:

• Maharashtra, Kerala, and Tamil Nadu received half of all remittances.
• Other states like Haryana, Gujarat, and Punjab had smaller shares (below 5%).

Size of Remittances:

• 28.6% of remittances were above 5 lakh.
• 40.6% of remittances were 16,500 or less.

3. Hydrogen Bomb Innovation: A Game-Changer for Modern Warfare

Context: Chinese researchers have reportedly tested a new hydrogen bomb that uses magnesium hydride to sustain a fireball — achieving a thermonuclear reaction without using traditional nuclear materials.

What is a Hydrogen Bomb?

A Hydrogen Bomb, or Thermonuclear Bomb, traditionally operates through a two-stage detonation process:

• Primary Stage (Fission Trigger): Uses fissile material such as uranium-235 or plutonium-239 to generate immense heat and pressure.
• Secondary Stage (Fusion Reaction): Under extreme conditions, hydrogen isotopes (deuterium and tritium) undergo fusion, releasing an energy yield many times greater than a pure fission bomb.

What is a Fissile-Free Hydrogen Bomb?

China’s breakthrough represents a fissile-free thermonuclear device. Instead of relying on fission, alternative ignition systems are used:

• Inertial Confinement Fusion (ICF): High-powered lasers compress and heat a small pellet of hydrogen isotopes to initiate fusion.
• Magnetic Compression (Z-pinch Systems): Magnetic fields rapidly compress plasma to achieve the high pressure needed for fusion reactions.

Key Difference: No uranium or plutonium is required, making it technically non-nuclear under traditional definitions.

Key Concerns Arising from this Innovation:

1. Legal Loopholes:

• Nuclear treaties like the Nuclear Non-Proliferation Treaty (NPT) and Comprehensive Test Ban Treaty (CTBT) focus on fissile material.
• Fissile-free devices could bypass treaty restrictions, undermining global arms control efforts.

2. Ease of Development:

• Fusion fuels like deuterium and tritium are less regulated compared to fissile materials.
• Fusion technologies are embedded in civilian research (e.g., energy programs), making dual-use activities harder to monitor.

3. Proliferation Risk:

• Rogue states or terror groups could exploit the new pathway to build powerful weapons without conventional nuclear infrastructure.

4. Asymmetric Warfare Implications:

• Compact, high-yield, and non-radioactive bombs could be:
  • Used in covert operations.
  • Deployed in gray-zone warfare tactics.

• Smuggled across borders.
• Disguised as industrial accidents.

Way Ahead:

Redefining International Law:

• Update the CTBT to explicitly ban non-fissile thermonuclear tests.
• Rethink definitions of nuclear weapons based on energy yield, not merely material composition.

Strengthening Verification Mechanisms:

• Establish a Fusion Weapons Verification Body (FWVB) under the International Atomic Energy Agency (IAEA), similar to the Organisation for the Prohibition of Chemical Weapons (OPCW).

India’s Strategic Response:

• India, guided by its credible minimum deterrence doctrine, must address the emerging strategic uncertainties.
• Invest in technologies that can detect non-radiological fusion detonations to safeguard national security.

4. Yellowstone Supervolcano: Latest Discovery and Its Implications

5. Zero Shadow Day (ZSD): A Fascinating Celestial Event

Context: The Cosmology Education and Research Training Center (COSMOS) in Mysuru, under the Indian Institute of Astrophysics, recently observed ‘Zero Shadow Day’.

What is Zero Shadow Day?

Zero Shadow Day (ZSD) is a unique celestial phenomenon where no shadow of any vertical object is seen at a particular location.

Why does it happen?

• It occurs when the Sun is exactly overhead at noon.
• On this day, the Sun’s declination becomes equal to the latitude of the location.
• As the Sun crosses the local meridian, its rays fall exactly vertically on objects, eliminating their shadows.

Scientific Explanation:

• Due to the tilt of Earth’s axis and its revolution around the Sun, the angle of sunlight hitting Earth changes throughout the year.
• This change in the Sun’s angle affects shadow lengths and directions.
• When the Sun is exactly overhead, shadows disappear briefly, creating the Zero Shadow Day effect.

When Does Zero Shadow Day Occur?

• ZSD happens twice a year for locations between the Tropic of Cancer and the Tropic of Capricorn.
• It corresponds to:
  • Uttarayan (when the Sun moves northward).
  • Dakshinayan (when the Sun moves southward).

Duration: The exact “zero shadow” moment lasts for a fraction of a second, but the visible effect can persist for about one to one-and-a-half minutes.

Where Can It Be Observed in India?

• ZSD can be seen in regions south of Bhopal, covering a wide range of Indian states, including:

Zero Shadow Day is a remarkable reminder of the dynamic relationship between Earth and the Sun, and how simple observations can reveal profound truths about our planet’s movements.

6. Climate Crisis and Gender-Based Violence: Urgent Call to Action

Context: A report released by the UN Spotlight Initiative highlights a growing crisis: climate change is worsening gender-based violence (GBV), particularly in vulnerable communities.

The report predicts that by 2100, climate change could be responsible for 1 in 10 cases of intimate partner violence (IPV) if urgent action is not taken.

Understanding the UN Spotlight Initiative:

The Spotlight Initiative is a global partnership between the European Union (EU) and the United Nations (UN), dedicated to eliminating violence against women and girls (VAWG) worldwide.

Key Findings from the UN Report on Climate and Gender-Based Violence:

Climate Change Intensifies GBV:

• A 1°C rise in temperature results in a 4.7% increase in intimate partner violence (IPV).
• With 2°C of warming, 40 million more women and girls could face IPV annually by 2090. This number more than doubles with 3.5°C of warming.
• Limiting the temperature increase to 1.5°C could reduce IPV rates from 24% to 14% by 2060.

Disaster-Induced Violence & Underreporting:

• In 2023, 93.1 million people faced climate disasters, and 423 million women suffered IPV.
• Heatwaves caused a 28% rise in femicide. Post-disaster situations often lead to an increase in child marriage, human trafficking, and sexual exploitation.
• Gender-based violence is described as a “shadow pandemic”, with one in three women globally experiencing physical, sexual, or psychological abuse, and only 7% of survivors reporting the incidents.

Vulnerable Groups at Highest Risk:

• Women in poverty, informal settlements, agriculture, Indigenous communities, those with disabilities, the elderly, and LGBTQ+ individuals are at higher risk of GBV due to limited support systems.
• Women advocating for environmental rights face harassment, violence, abduction, and even murder.

Huge Gap in Gender-Climate Funding:

• Only 0.04% of climate-related development assistance focuses on gender equality, signaling a massive gap in addressing GBV within climate action.

Key Recommendations from the UN Report:

Integrating GBV in Climate Policy:

• It is crucial to mainstream GBV prevention into all climate policies and programs at the local, national, and global levels, with an increase in gender-focused climate funding.

Prioritize Women’s Safety and Leadership:

• Ensure women are central to climate solutions as both leaders and beneficiaries.
• Acknowledge and address GBV as a barrier to climate resilience, making it a core part of sustainable development efforts.

Supporting Women’s Movements:

• Strengthen the capacity of civil society organizations and women’s movements, such as the Pacific Feminist Community of Practice, to ensure gender justice is central to global climate platforms like COP27.

Adopting International Best Practices:

• Implement gender-responsive programs as seen in Vanuatu, Liberia, and Mozambique, linking gender justice with climate resilience.
• Key measures include:
  • Retraining former FGM practitioners in climate-smart agriculture.
  • Embedding GBV services in disaster response.
  • Deploying mobile health clinics in climate-affected areas.