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Subject: Space Technology

  • ISRO to test improved fire detection algorithm during rabi harvest  

    Why in the News?

    Indian Space Research Organisation will pilot a modified algorithm to better detect farm fire events during the upcoming wheat harvesting season. The move follows discrepancies between satellite detected fires and ground reports flagged by the Commission for Air Quality Management.

    Background: Stubble Burning

    • Paddy stubble generated within a 30 day window in Punjab, Haryana and western UP.
    • Farmers burn residue due to:
      • Short gap between harvest and next sowing cycle
      • Low cost and quick clearance
    • Burning releases PM2.5 and gaseous pollutants.
    • During peak season, farm fires can contribute up to 40 percent of Delhi pollution load.

    Satellite Monitoring Mechanism

    • Fire data based on sun synchronous polar orbiting satellites:
      • NASA Terra and Aqua using MODIS sensor
      • National Oceanic and Atmospheric Administration Suomi NPP using VIIRS sensor
    • Issue identified:
      • Peak burning time shifted from around 1.30 pm in 2020 to nearly 5 pm in 2024.
      • Late evening fires may escape detection due to fixed satellite overpass timings.
    • Rabi Season Focus
      • Wheat harvesting: Late March to May.
    • 2025 data recorded:
      • Punjab: 10,207 fire events
      • Haryana: 1,832
      • NCR districts of UP: 259
    • For first time, CAQM directing monitoring of summer wheat stubble burning.
    [2019] For the measurement/estimation of which of the following are satellite images/remote sensing data used? 1. Chlorophyll content in the vegetation of a specific location 

    2. Greenhouse gas emissions from rice paddies of a specific location 

    3. Land surface temperatures of a specific location 

    Select the correct answer using the code given below: 

    (a) 1 only (b) 2 and 3 only (c) 3 only (d) 1, 2 and 3

  • On gravity’s role on Earth’s journey through space

    Why in the News?

    The article becomes relevant at the start of a new year, as it reflects on Earth’s continuous journey around the Sun at nearly 1,07,000 km per hour. It points out that even at such enormous speed, life remains stable because gravity keeps everything in balance. The piece recalls an important scientific milestone, the rejection of the ether theory in 1887, and pays tribute to Prof. Jayant Narlikar, founder of IUCAA, after his recent passing. It contrasts old beliefs about “aether” with today’s scientific understanding of vacuum and gravitational forces. The striking figures, Earth travelling nearly 1 billion kilometres in a year and about 40,000 kilometres in an hour, highlight how vast this motion is, even though we do not feel it in everyday life.

    What is Gravity?

    1. Gravity is a fundamental, invisible force of attraction that pulls any two objects with mass toward each other. 
    2. Its strength depends on the mass of the objects and the distance between them
    3. Gravity governs both terrestrial and cosmic systems. 
    4. It explains falling objects, planetary motion, and Earth’s stable revolution around the Sun. 
    5. The Earth completes one revolution in 365 days while travelling nearly one billion kilometres annually at high velocity. This motion remains unnoticed due to gravitational balance and absence of resistive friction in space.

    How Does Gravity Function as a Centripetal Force?

    1. Centripetal Mechanism: Gravity acts as the centripetal force pulling bodies towards a centre, ensuring orbital motion.
    2. Bicycle Analogy: Pulling a string tied to a rotating object redirects its motion inward, similar to gravitational pull maintaining planetary orbits.
    3. Planet-Sun Interaction: Earth does not fall into the Sun because forward motion balances gravitational pull.
    4. Universal Application: The same mechanism explains the Earth-Moon system and other celestial rotations.

    Why Do Objects Fall Toward Earth?

    1. Universal Gravitation: Objects fall toward Earth because Earth is the heaviest nearby mass.
    2. Mass Attraction: All objects with mass attract one another.
    3. Everyday Example: Falling bodies move toward Earth’s centre unless acted upon by another force.

    How Fast Is Earth Travelling in Space?

    1. Annual Distance: Earth travels nearly 1,000,000,000 km in one year.
    2. Hourly Speed: Approximate orbital speed equals 1,07,000 km per hour.
    3. Comparative Illustration: A car travelling at 100 km per hour without stopping would take around 1,000 years to cover a comparable distance.
    4. Temporal Perspective: Earth covers nearly 40,000 km in about one hour.

    Why Is There No Friction in Space?

    1. Friction Concept: Friction arises due to surrounding particles resisting motion.
    2. Earthly Examples: Air slows a bird; water resists a fish; road friction stops a car.
    3. Vacuum Condition: Space lacks resisting medium, preventing deceleration of planetary motion.
    4. Energy Continuity: Continuous motion persists without need for refuelling unlike vehicles requiring oil.

    What Was the Ether Hypothesis and Why Did It Fail?

    1. Ether Assumption: Earlier belief held that an invisible material called “aether” filled space.
    2. Michelson-Morley Experiment (1887): Attempted to detect ether; failed to find evidence.
    3. Scientific Outcome: Demonstrated absence of ether, marking a major conceptual correction.
    4. Modern Understanding: Space functions as vacuum without a resistive medium.

    What Is the Significance of Space Studies in India?

    1. Institutional Role: IUCAA in Pune advances astrophysics research.
    2. Scientific Leadership: Prof. Jayant Narlikar contributed to cosmological theories and public science communication.
    3. Recognition: Awarded Padma Vibhushan in 2004.
    4. Public Outreach: Science communication through television series such as “Brahmand.”

    Conclusion

    Earth’s silent, high-speed journey through space is sustained by the precise balance of gravity and motion. What once required speculative ideas like “ether” is now explained through tested scientific principles. By reflecting on these discoveries, and the contributions of scientists like Jayant Narlikar, it reinforces the importance of scientific temper in understanding our place in the universe.

    PYQ Relevance

    [UPSC 2017] How does the Juno Mission of NASA help to understand the origin and evolution of earth?

    Linkage: Juno’s study of Jupiter’s gravitational structure reinforces the article’s explanation of gravity as the fundamental force shaping Earth’s origin and sustaining its motion through space.

  • Safe Landing Patch Identified near Mons Mouton for Chandrayaan 4

    Why in the News

    A study by ISRO Space Applications Centre has identified a safe landing patch near Mons Mouton for Chandrayaan-4, India’s first lunar sample return mission.

    About Moon’s Mons Mouton

    • Mons Mouton is a large flat topped lunar mountain massif
    • Officially named by the International Astronomical Union

    Location

    • Situated in the south polar region of the Moon
    • Lies close to the rim of the South Pole Aitken Basin
    • Approximately 160 km from the lunar south pole

    Origin

    • Formed due to rim uplift during ancient massive asteroid impacts
    • Represents exposed deep lunar crust, rare and scientifically valuable

    Key Physical Features

    • Width of nearly 100 km
    • Elevation of about 6,000 metres above surrounding terrain
    • Rugged topography with craters and boulder fields
    • Unique illumination conditions
      • Some regions receive near continuous sunlight
      • Others remain in permanent shadow
    • Can be observed during favourable libration even with amateur telescopes
    [2009] India has recently landed its Moon Impact Probe on the Moon. Among the following countries, which one landed such probe on the Moon earlier? (a) Australia 

    (b) Canada 

    (c) China 

    (d) Japan

  • Stealth Coronal Mass Ejection and Geomagnetic Storm

    Why in the News?

    Astronomers have identified a Stealth Coronal Mass Ejection (CME) as the cause of an intense geomagnetic storm in March 2023, revealing major challenges in space weather forecasting.

    What is a Stealth CME?

    • A weak and faint Coronal Mass Ejection with little or no visible solar signatures
    • Lacks common warning signs like X ray flares or radio bursts
    • Often escapes detection by conventional solar observation tools
    • Responsible for nearly 10 percent of intense geomagnetic storms

    What is a Geomagnetic Storm?

    • A temporary disturbance of Earth’s magnetosphere
    • Triggered by solar wind shocks or CMEs interacting with Earth’s magnetic field
    • Strongest effects when the interplanetary magnetic field is southward

    Key Scientific Findings

    • The stealth CME erupted on 19 March 2023
    • It travelled through a coronal hole, a region of open magnetic field releasing high speed solar wind
    • This enabled the weak CME to reach Earth and trigger a strong storm after about three days
    • CMEs near coronal holes get accelerated, increasing their Earth impact potential
    [2022] If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? 1. GPS and navigation systems could fail. 

    2. Tsunamis could occur at equatorial regions. 

    3. Power grids could be damaged. 

    4. Intense auroras could occur over much of the Earth. 

    5. Forest fires could take place over much of the planet. 6. Orbits of the satellites could be disturbed. 

    7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted. 

    Select the correct answer using the code given below: 

    (a) 1, 2, 4 and 5 only (b) 2, 3, 5, 6 and 7 only (c) 1, 3, 4, 6 and 7 only (d) 1, 2, 3, 4, 5, 6 and 7

  • Rare Blood Red Aurora over Ladakh 

    Why in the News?

    A rare blood red aurora was observed over Hanle in Ladakh on 19–20 January 2026 following a powerful geomagnetic storm triggered by a fast coronal mass ejection from the Sun.

    Key Facts about the Event

    • Observed at the Indian Astronomical Observatory, Hanle
    • Captured by an all sky camera operated by the Indian Institute of Astrophysics
    • Sixth such intense red aurora recorded at Hanle during the current solar cycle
    • Rare because auroras usually occur near polar regions, not mid latitudes like Ladakh

    Cause of the Red Aurora

    • Triggered by a Coronal Mass Ejection (CME) launched on 18 January
    • CME associated with an X1.9 class solar flare
    • Originated from Active Region 14341 near the centre of the Sun
    • CME interacted with Earth’s magnetosphere
    • Resulted in a G4 level geomagnetic storm on the NOAA scale classified as severe

    Why the Aurora Appeared Red

    • Caused by excitation of oxygen atoms in the upper atmosphere
    • Occurs at high altitudes around 200 to 400 km
    • Red auroras are rarer than green ones and indicate strong space weather

    [2012] Electrically charged particles from space travelling at speeds of several hundred km/sec can severely harm living beings if they reach the surface of the Earth. What prevents them from reaching the surface of the Earth? 

    (a) The Earth’s magnetic field diverts them towards its poles 

    (b) Ozone layer around the Earth reflects them back to outer space 

    (c) Moisture in the upper layers of atmosphere prevents them from reaching the surface of the Earth 

    (d) None of the statements (a), (b) and (c) given above is correct

  • Reconstructing the Sun’s Invisible Magnetic Fields

    Why in the News?

    Researchers from Indian Institute of Technology Kanpur have reconstructed the internal magnetic fields of the Sun using 30 years of surface data, improving the ability to predict solar cycles and space weather. The study was published on January 20 in Astrophysical Journal Letters.

    Background

    • The Sun follows an ~11 year solar activity cycle driving sunspots, solar flares and coronal mass ejections
    • These events affect satellites, navigation systems, power grids and communications on Earth
    • Prediction is difficult because magnetic fields originate deep inside the Sun, beyond direct observation

    What is New in This Study?

    • Instead of relying on simplified theoretical assumptions, researchers used a data driven solar dynamo model
    • Real observations of surface magnetic fields were fed into a 3D computer simulation
    • This allowed reconstruction of the invisible magnetic fields inside the Sun

    Key Scientific Findings

    • Successfully reproduced the Butterfly Diagram, showing sunspot migration from high latitudes to the equator
    • Revealed behaviour of the toroidal magnetic field in the Sun’s convection zone
    • Internal magnetic field strength matched actual Solar Cycles 23, 24 and 25

    Significance

    • Advances understanding of solar dynamo physics
    • Enhances space weather forecasting accuracy
    • Critical for protecting space based assets and communication infrastructure
    [2022] If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? 

    1. GPS and navigation systems could fail. 

    2. Tsunamis could occur at equatorial regions. 

    3. Power grids could be damaged. 

    4. Intense auroras could occur over much of the Earth. 

    5. Forest fires could take place over much of the planet. 

    6. Orbits of the satellites could be disturbed. 

    7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted. Select the correct answer using the code given below: 

    (a) 1, 2, 4 and 5 only (b) 2, 3, 5, 6 and 7 only (c) 1, 3, 4, 6 and 7 only (d) 1, 2, 3, 4, 5, 6 and 7

  • Strongest Solar Radiation Storm in Over 20 Years

    Why in the News?

    The Sun has unleashed the strongest solar radiation storm in more than 20 years, triggering rare auroras across Europe and the United States and raising concerns over satellites, aviation, power grids, and astronaut safety. The storm is the most intense since October 2003.

    What is a Solar Radiation Storm?

    • A solar radiation storm occurs when the Sun releases a burst of fast moving, highly charged particles toward Earth
    • These particles can penetrate Earth’s magnetic field and increase radiation levels in space and at high altitudes
    • Defined and monitored by NASA and the Space Weather Prediction Center

    Severity and Classification

    • Classified as Level 4 out of 5 (Severe) on the solar radiation storm scale
    • Strongest event of its kind since October 2003
    • Occurred during the peak phase of the Sun’s 11 year solar cycle

    Prelims Pointers

    • Solar radiation storms mainly affect space based and high altitude systems
    • They are rare and most frequent near solar maximum
    • Auroras result from interaction between solar particles and Earth’s magnetic field
    • CMEs and solar flares are solar origin phenomena, not atmospheric events
    [2022] If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? 

    1. GPS and navigation systems could fail

    2. Tsunamis could occur at equatorial regions

    3. Power grids could be damaged

    4. Intense auroras could occur over much of the Earth

    5. Forest fires could take place over much of the planet

    6. Orbits of the satellites could be disturbed

    7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted

    Select the correct answer using the code given below: 

    (a) 1, 2, 4 and 5 only (b) 2, 3, 5, 6 and 7 only (c) 1, 3, 4, 6 and 7 only (d) 1, 2, 3, 4, 5, 6 and 7

  • Artemis II Mission

    Why in the News

    NASA is targeting 6 February for the launch of Artemis II, its first crewed lunar mission under the Artemis programme, marking humanity’s return to lunar spaceflight after more than 50 years since Apollo 17.

    What is Artemis II

    • First crewed mission of the Artemis programme
    • Sends astronauts around the Moon, not a lunar landing
    • Mission duration about 10 days
    • Objective is to test human rated deep space systems

    Artemis Programme Context

    • Artemis I: Conducted in August 2022. First integrated flight of Orion and SLS
    • Artemis III: Scheduled around 2027. Aims to land astronauts at the Moon’s south pole.

    Prelims Pointers

    • Artemis II is a crew flyby mission, not a landing mission
    • First humans to travel beyond low Earth orbit since 1972
    • Orion uses a free return trajectory
    • Artemis programme aims at Moon to Mars pathway
    • International participation includes Canada
    • Splashdown planned in Pacific Ocean
    [2025] Consider the following space missions: 

    I. Axiom-4 

    II. SpaDeX 

    III. Gaganyaan 

    How many of the space missions given above encourage and support microgravity research? 

    (a) Only one (b) Only two (c) All the three (d) None

  • How reusability can lead to sustainable, cost effective access to space

    Why in the News

    Reusable rocket technology has shifted space activities from government-controlled, single-use rockets to a commercial, reuse-based model. Private companies, especially SpaceX, have repeatedly recovered and reused rocket stages, cutting launch costs by nearly five times and allowing more frequent launches. With the global space economy expected to cross USD 1 trillion by 2030, reusability marks a fundamental break from earlier disposable launch systems that dominated for decades.

    Reusable rocket

    1. It is a spacecraft designed to launch, land, and be refurbished for multiple flights.
    2. It drastically cuts space access costs by reusing expensive components like the booster, with SpaceX’s Falcon 9 leading the way.
    3. How They Work (Key Technologies)
      1. Vertical Takeoff & Landing (VTVL): Rockets launch vertically and use engines, grid fins (like on Falcon 9), and landing legs for controlled descent and landing back on Earth.
      2. Advanced Software: Sophisticated flight computers and software manage complex maneuvers like boost-back burns, re-entry burns, and final landing.
      3. Fuel Reserve: Reusable rockets carry extra fuel to perform landing burns, making them heavier but efficient.
      4. Refurbishment: After landing, components are inspected, refurbished, and prepared for the next flight, reducing the need to build new rockets.

    How does rocket fuel mass constrain space launches?

    1. Rocket Equation Constraint: Demonstrates that most launch mass consists of fuel, leaving less than 3-4% for payload in conventional designs.
    2. Propellant Dominance: Requires carrying fuel to lift fuel, creating diminishing returns for payload capacity.
    3. Cost Implication: Increases launch expenses as entire systems are discarded after one mission.

    Why are rockets designed with multiple stages?

    1. Stage Separation: Allows discarding empty tanks and engines to reduce mass during ascent.
    2. Efficiency Gain: Improves thrust-to-weight ratio as the vehicle ascends.
    3. Conventional Limitation: Most stages are used once and destroyed, increasing per-launch costs.

    How has reusability altered rocket engineering economics?

    1. Stage Recovery: Enables retrieval of high-value components such as engines and avionics.
    2. Manufacturing Shift: Reduces dependence on repeated fabrication of complex propulsion systems.
    3. Launch Frequency: Supports rapid turnaround and higher mission cadence.

    What operational innovations enable reusable launch systems?

    1. Precision Landing: Uses autonomous guidance, grid fins, and controlled burns for vertical recovery.
    2. Thermal and Structural Design: Ensures engines and stages withstand re-entry heat and stress.
    3. Refurbishment Protocols: Introduces inspection, testing, and component replacement cycles.

    Can a recovered rocket stage be reused multiple times?

    1. Reuse Cycles: First stages of Falcon-9 rockets have been reused over 30 times.
    2. Economic Threshold: Savings from reuse outweigh refurbishment and inspection costs.
    3. Reliability Assurance: Requires rigorous testing to maintain safety and mission assurance.

    How does reusability improve sustainability in space operations?

    1. Material Efficiency: Reduces consumption of metals, composites, and rare components.
    2. Debris Reduction: Limits discarded stages that contribute to space and ocean debris.
    3. Environmental Impact: Lowers lifecycle emissions by minimizing repeated manufacturing.

    What are the limitations of reusable rocket technology?

    1. Engineering Trade-offs: Recovery systems add mass, reducing payload capacity.
    2. Thermal Stress: Engines face extreme heat cycles during re-entry and relaunch.
    3. Economic Ceiling: Excessive inspection or refurbishment can negate cost benefits.

    Where does India stand in reusable launch vehicle development?

    1. ISRO Initiatives: Working on reusable launch vehicles (RLVs), winged spaceplane concepts, and vertical landing experiments.
    2. Two-Stage Focus: Aims to achieve orbital missions with fewer stages through high-efficiency propulsion.
    3. Private Sector Entry: Indian startups are exploring recovery-based launch solutions.
    4. Future Direction: Emphasis on recovery, reuse, and refurbishment for competitive access to space.

    Conclusion

    Reusable launch systems redefine space access by replacing disposable rockets with recoverable transportation platforms. By lowering costs, increasing mission frequency, and reducing material waste, reusability strengthens both economic viability and sustainability of space operations. For India, adopting reusability is essential to remain competitive in a rapidly commercialising global space economy.

    PYQ Relevance

    [UPSC 2016] Discuss India’s achievements in the field of Space Science and Technology. How has the application of this technology helped India in its socio-economic development?

    Linkage: India’s achievements in space technology, low-cost launch systems, planetary missions, and indigenous satellites, demonstrate technological self-reliance and innovation. Their application has directly supported socio-economic development through communication, disaster management, navigation, weather forecasting, and governance efficiency (GS III: Space Technology & Development).

  • Universe, Solar System Discoveries