GS Notes

19. Science and Technology Notes 01

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Elaborate Notes

Overview of Science and Technology in UPSC

The subject of Science and Technology holds significant weightage in the UPSC Civil Services Examination. It consistently features in both the Preliminary and Main examinations, reflecting its growing importance in governance, international relations, and economic development.

  • Relevance: An average of 13-14 questions appear in the Preliminary examination, primarily focusing on current developments in emerging technologies. In the Main examination (General Studies Paper-III), it constitutes a significant portion with 2-4 questions, demanding an analytical understanding of technology’s impact on society and economy.
  • Sources: A multi-pronged approach is necessary for comprehensive coverage.
    • Foundation: NCERT textbooks for classes 9th and 10th provide the fundamental scientific principles.
    • Current Affairs: Newspapers like The Hindu and The Indian Express are indispensable for tracking recent developments.
    • Consolidation: Monthly current affairs magazines help in structuring and revising the information.
    • Digital Resources: Reputed YouTube channels for conceptual clarity, and government websites like www.indiascience.in and Prasar Bharati provide authentic information on India’s achievements.
  • Syllabus Coverage: The domain is vast and interdisciplinary. Key areas include:
    • Space Technology: Orbits, satellites, launch vehicles, and missions of ISRO.
    • Nuclear Technology: Nuclear fission and fusion, India’s three-stage nuclear program, and applications.
    • Information and Communication Technology (ICT) & Robotics: AI, IoT, 5G, Quantum Computing, and automation.
    • Intellectual Property Rights (IPR): Patents, copyrights, trademarks, and related international conventions.
    • Defence Technology: Missiles, submarines, aircraft, and indigenous development programs.
    • Contribution of Indian Scientists: Understanding the legacy and work of scientists like Homi J. Bhabha, Vikram Sarabhai, and C.V. Raman.

Foundations of Space Technology

The ability to place satellites in orbit and send probes into deep space is governed by fundamental laws of physics, articulated centuries ago.

  • Newton’s Three Laws of Motion: Sir Isaac Newton, in his seminal work Philosophiæ Naturalis Principia Mathematica (1687), laid the groundwork for classical mechanics. These laws are central to rocket science.
    • First Law (Law of Inertia): An object remains at rest or in uniform motion in a straight line unless acted upon by an external force. This explains why a satellite, once in orbit, continues to move without constant propulsion.
    • Second Law (F = ma): The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This is the core principle of rocket propulsion: the force (thrust) generated by expelling mass (exhaust gases) at high velocity causes the rocket of a certain mass to accelerate.
    • Third Law (Action-Reaction): For every action, there is an equal and opposite reaction. This is the most direct principle behind rocketry. The downward expulsion of hot gases from the rocket engine (action) creates an equal and upward force (reaction) that lifts the rocket.
  • Vectors and Scalars: In physics, quantities are classified as either scalar (having only magnitude, e.g., mass, time, speed) or vector (having both magnitude and direction, e.g., velocity, force, acceleration). Understanding this distinction is crucial for calculating trajectories, thrust, and orbital paths, which are all vector-dependent.
  • Kepler’s Laws of Planetary Motion: Johannes Kepler, using the meticulous astronomical data collected by Tycho Brahe, formulated three laws that describe the motion of planets around the Sun. Published in his books Astronomia Nova (1609) and Harmonices Mundi (1619), these laws are universally applicable to any satellite orbiting a central body, including artificial satellites orbiting Earth.
    • The Law of Orbits: “Every planet revolves around the sun in an elliptical orbit with the sun being at one of the foci of the ellipse.” This means the distance between a satellite and the Earth is not constant. The closest point is called the perigee, and the farthest point is the apogee.
    • The Law of Equal Areas: “A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.” This implies that a satellite travels faster when it is closer to the Earth (at perigee) and slower when it is farther away (at apogee).
    • The Law of Periods: “The square of the time period of revolution of a planet is proportional to the cube of the semi-major axis of its elliptical orbit” (T² ∝ a³). This law provides a precise mathematical relationship between the size of a satellite’s orbit (a) and the time it takes to complete one revolution (T). This allows scientists to calculate the required altitude for a desired orbital period, such as 24 hours for a geosynchronous satellite.
  • Centripetal Force: For an object to move in a circular or elliptical path, it must be continuously pulled towards the center of the orbit by a force. This force is known as the centripetal force. In the case of a satellite orbiting the Earth, this force is provided by the Earth’s gravitational attraction. The satellite is in a constant state of “falling” towards the Earth, but its tangential velocity is so high that it continuously “misses” the Earth, resulting in a stable orbit.

Types of Orbits

Orbits are categorized based on various parameters like altitude, inclination, and synchronicity with Earth’s motion. The choice of orbit depends entirely on the mission’s objective.

  • Classification Based on Height:

    • Low Earth Orbit (LEO): Extends from an altitude of approximately 180 km to 2,000 km.
      • Advantages: It is the easiest and cheapest to reach. The proximity to Earth allows for high-resolution imagery. Communication latency is very low.
      • Disadvantages: A satellite in LEO has a small field of view and covers only a fraction of the Earth’s surface at any given time. Due to atmospheric drag, even at these altitudes, orbits decay over time, requiring periodic re-boosting.
      • Examples: The International Space Station (ISS), the Hubble Space Telescope, Earth observation satellites like India’s RISAT series, and satellite constellations for internet services like SpaceX’s Starlink.
    • Medium Earth Orbit (MEO): Situated between LEO and High Earth Orbit, from 2,000 km to just below 35,786 km.
      • Characteristics: It offers a good compromise between the wide coverage of high orbits and the low latency of LEO. Satellites in MEO have a longer orbital period (typically 2-12 hours).
      • Examples: Primarily used for navigation satellite systems, which require a constellation of satellites to provide global coverage. Examples include the USA’s Global Positioning System (GPS), Russia’s GLONASS, European Union’s Galileo, and India’s NavIC.
    • High Earth Orbit (HEO): Any orbit with an altitude higher than a geosynchronous orbit (35,786 km).
      • Characteristics: These orbits are used for specialized scientific missions, such as studying Earth’s magnetosphere or for deep space observation.

  • Classification Based on Inclination: Inclination is the angle of the orbital plane with respect to the Earth’s equatorial plane.

    • Equatorial Orbit: The inclination is 0 degrees. The satellite orbits directly above the equator. This is the path for all geostationary satellites.
    • Polar Orbit: The inclination is approximately 90 degrees. The satellite passes over or very near to the Earth’s North and South poles on each revolution.
      • Utility: As the Earth rotates beneath the satellite, a polar orbit allows the satellite to observe the entire surface of the Earth over time. This makes it extremely useful for remote sensing, mapping, and reconnaissance.
      • Launch Consideration: Launching into a polar orbit from a site like Sriharikota does not benefit from the Earth’s rotational velocity (which is maximum at the equator and directed eastwards). This requires more fuel and a more powerful rocket compared to an equatorial launch.
    • Inclined Orbit: Any orbit with an inclination between 0 and 90 degrees.
    • Sun-Synchronous Polar Orbit (SSPO): A special type of polar orbit where the satellite passes over any given point on the Earth’s surface at the same local solar time. This is achieved by carefully selecting the altitude and inclination. It is highly desirable for Earth observation missions because the constant angle of sunlight illumination makes it easier to compare images taken on different days.

  • Classification Based on Earth’s Motion (Synchronicity):

    • Geosynchronous Orbit (GSO): A satellite in this orbit has an orbital period that exactly matches the Earth’s rotational period—one sidereal day (23 hours, 56 minutes, 4 seconds). This means the satellite returns to the same position in the sky after each day. The orbit can be elliptical and inclined.
    • Geostationary Orbit (GEO): This is a special case of a GSO. A satellite in a geostationary orbit must satisfy three conditions:
      1. It must be in a Geosynchronous orbit (orbital period of one sidereal day).
      2. It must be in a circular orbit (not elliptical).
      3. It must be in an equatorial orbit (inclination of 0 degrees).
      • Effect: A satellite meeting these conditions appears to be stationary or “fixed” at a single point in the sky when viewed from the ground.
      • Altitude: This orbit exists at a very specific altitude of 35,786 km above the equator.
      • Applications: Ideal for communication satellites (e.g., DTH television, satellite telephony) and weather monitoring satellites (e.g., India’s INSAT series) as the ground-based antennas do not need to track the satellite. The concept was first popularised by the science fiction writer Arthur C. Clarke in a 1945 paper, leading to this orbital belt sometimes being called the Clarke Belt.
      • Regulation: The geostationary orbit is a limited natural resource. The International Telecommunication Union (ITU), a specialized agency of the United Nations, is responsible for allocating orbital slots and frequency bands to countries to prevent interference.

Prelims Pointers

  • Newton’s Laws of Motion: Formulated by Sir Isaac Newton in Principia Mathematica (1687).
    • First Law: Inertia.
    • Second Law: F=ma (Force = mass × acceleration).
    • Third Law: Action-Reaction. Rocket propulsion is based on the third law.
  • Kepler’s Laws of Planetary Motion:
    • First Law: Orbits are elliptical, with the central body at one focus.
    • Second Law: A satellite sweeps equal areas in equal intervals of time. It moves fastest at perigee (closest point) and slowest at apogee (farthest point).
    • Third Law: T² ∝ a³ (Square of orbital period is proportional to the cube of the semi-major axis).
  • Orbital Altitudes:
    • Low Earth Orbit (LEO): 180 km - 2,000 km.
    • Medium Earth Orbit (MEO): 2,000 km - 35,786 km.
    • High Earth Orbit (HEO): Above 35,786 km.
  • Geosynchronous Orbit (GSO):
    • Orbital period matches Earth’s sidereal day (23 hours, 56 minutes, 4 seconds).
    • Can be inclined and elliptical.
  • Geostationary Orbit (GEO):
    • A special case of GSO.
    • Altitude: 35,786 km.
    • Orbit type: Circular.
    • Inclination: 0 degrees (equatorial).
    • Appears stationary from Earth.
  • Polar Orbit:
    • Inclination is approximately 90 degrees.
    • Allows for observation of the entire Earth’s surface over time.
    • Does not gain velocity boost from Earth’s rotation.
  • Sun-Synchronous Polar Orbit (SSPO):
    • A specific type of polar orbit.
    • Satellite passes over a point at the same local solar time.
    • Useful for Earth observation and remote sensing.
  • International Telecommunication Union (ITU):
    • A UN specialized agency.
    • Regulates and allocates orbital slots in the geostationary orbit and frequency spectrums.
  • Clarke Belt: Another name for the Geostationary Orbit, named after Arthur C. Clarke.

Mains Insights

GS Paper III: Science & Technology, Economy, Security

  1. Strategic Importance of Space Technology:

    • Dual-Use Nature: The technologies developed for space (e.g., rocketry, satellite imaging) have both civilian and military applications. For example, high-resolution imagery from Earth observation satellites can be used for urban planning (civilian) as well as for surveillance and intelligence gathering (military). This duality makes space a critical domain for national security.
    • Geopolitical Competition and Cooperation: Space is an arena for both competition (e.g., the historical space race between the US and USSR) and cooperation (e.g., the International Space Station). A nation’s space capabilities are a key indicator of its technological prowess and influence on the global stage. India’s Mars Orbiter Mission (Mangalyaan) and Chandrayaan missions have significantly enhanced its international standing.
    • National Security: Modern warfare is heavily dependent on space assets for communication, navigation (GPS/NavIC), and ISR (Intelligence, Surveillance, and Reconnaissance). The development of Anti-Satellite (ASAT) weapons, demonstrated by India in Mission Shakti (2019), underscores the militarization of space and the need for robust space situational awareness.

  2. Socio-Economic Applications of Space Technology:

    • Connecting the Unconnected: Communication satellites (like India’s GSAT series in GEO) are vital for tele-education, telemedicine, DTH broadcasting, and VSAT networks for banking, bridging the urban-rural digital divide.
    • Resource Management and Governance: Remote sensing satellites (like the Resourcesat series in Polar orbits) provide crucial data for agricultural yield forecasting, groundwater prospecting, forest cover monitoring, and infrastructure planning. This aids in evidence-based policymaking.
    • Disaster Management: Satellites provide early warnings for cyclones (e.g., INSAT-3DR), monitor floods and droughts, and assist in post-disaster damage assessment and relief operations, making governance more effective and responsive.
    • Navigation Services: India’s indigenous NavIC system reduces dependence on foreign systems like GPS, which can be denied during conflicts. It has commercial applications in fleet management, logistics, and mobile devices.

  3. Challenges and Debates in the Space Sector:

    • Space Debris: The proliferation of defunct satellites, rocket stages, and fragments in orbit, particularly in LEO, poses a significant threat to active satellites and future missions. The Kessler Syndrome, a scenario proposed by NASA scientist Donald J. Kessler in 1978, describes a runaway chain reaction of collisions that could render certain orbits unusable. This necessitates international cooperation on debris mitigation and remediation.
    • Regulation of the Space Domain: The primary international legal framework, the Outer Space Treaty of 1967, is considered outdated by some as it does not adequately address issues like commercial space activities, property rights on celestial bodies, or space debris. There is an ongoing debate on the need for new international norms and laws to govern the rapidly evolving space environment.
    • Privatization of Space: The entry of private players like SpaceX, Blue Origin, and in India, Skyroot Aerospace and Agnikul Cosmos, is revolutionizing the space sector by reducing costs and increasing innovation. However, this raises questions about regulation, safety standards, and ensuring that space remains a global common accessible to all nations, not just those with a dominant private sector.

GS Paper II: International Relations

  • Space Diplomacy: India uses its space capabilities as a tool of foreign policy. The launch of the SAARC Satellite (GSAT-9) in 2017 was a prime example of using space technology to foster regional cooperation and goodwill. Providing launch services for other countries through ISRO’s commercial arm also strengthens bilateral ties.

Previous Year Questions

Prelims

  1. With reference to the Indian regional navigation satellite system (IRNSS), consider the following statements: (UPSC Prelims 2018)

    1. IRNSS has three satellites in geostationary and four satellites in geosynchronous orbits.
    2. IRNSS covers the entire India and about 5500 sq. km beyond its borders.
    3. India has its own satellite navigation system with full global coverage by the middle of 2019.

    Which of the statements given above is/are correct? (a) 1 only (b) 1 and 2 only (c) 2 and 3 only (d) None

    Answer: (a) Explanation: Statement 1 is correct. Statement 2 is incorrect; it covers India and a region extending up to 1,500 km around it. Statement 3 is incorrect; IRNSS (NavIC) is a regional, not global, system.

  2. Consider the following statements: (UPSC Prelims 2019) The motion of a satellite in orbit around a planet is fastest when it is:

    1. At perigee
    2. At apogee
    3. At a point equidistant from perigee and apogee
    4. The speed is always constant in any orbit

    Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) 3 only (d) 4 only

    Answer: (a) Explanation: This is a direct application of Kepler’s Second Law of Planetary Motion (Law of Equal Areas). The satellite sweeps equal areas in equal time, meaning it must move fastest when it is closest to the central body (at perigee).

  3. In which of the following areas can GPS technology be used? (UPSC Prelims 2018)

    1. Mobile phone operations
    2. Banking operations
    3. Controlling the power grids

    Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

    Answer: (d) Explanation: GPS provides precise timing and location data. Mobile phones use it for navigation. Banks use GPS timing for synchronizing financial transactions. Power grids use it for precise time-stamping to manage the flow of electricity and detect faults (phasor measurement units).

  4. What is the purpose of the ‘evolved Laser Interferometer Space Antenna (eLISA)’ project? (UPSC Prelims 2017) (a) To detect neutrinos (b) To detect gravitational waves (c) To detect the effectiveness of missile defence system (d) To study the effect of solar flares on our communication systems

    Answer: (b) Explanation: eLISA (now known as LISA) is a proposed space-based mission designed to detect and measure gravitational waves, which are ripples in spacetime. It is a large-scale project by the European Space Agency (ESA).

  5. Consider the following pairs: (UPSC Prelims 2014)

    1. GISAT-1 : Geostationary satellite
    2. Megha-Tropiques : Satellite for studying tropical atmosphere
    3. Aditya-L1 : Mission to study the Sun

    Which of the above pairs is/are correctly matched? (a) 1 only (b) 1 and 2 only (c) 2 and 3 only (d) 1, 2 and 3

    Answer: (d) Explanation: All three pairs are correctly matched. GISAT-1 is a Geo-Imaging Satellite. Megha-Tropiques is an Indo-French joint satellite mission for studying the water cycle and energy exchanges in the tropics. Aditya-L1 is India’s first solar mission.

Mains

  1. What is India’s plan to have its own space station and how will it benefit our space programme? (UPSC Mains 2019, GS-III)

    Answer Structure:

    • Introduction: Briefly mention ISRO’s announcement post-Gaganyaan to establish its own space station by 2030, marking the next logical step in its human spaceflight program.
    • Details of the Plan:
      • Describe the proposed space station as a small module (around 20 tonnes).
      • Mention its intended orbit (LEO at ~400 km altitude).
      • Explain it will serve as a platform for microgravity experiments.
      • State that it will be launched in modules using Indian launch vehicles.
    • Benefits to India’s Space Programme:
      • Scientific Advancement: Enables long-term studies in microgravity on materials science, human biology, etc.
      • Technological Capability: Demonstrates advanced capabilities in docking, life support systems, and long-duration space missions.
      • Future Missions: Acts as a stepping stone or gateway for more ambitious interplanetary missions, including manned missions to the Moon or Mars.
      • Global Standing: Puts India in an elite club of nations with space stations, enhancing its geopolitical stature.
      • Commercial Opportunities: Can be used by other nations and private entities for research on a commercial basis.
    • Conclusion: Conclude by stating that an indigenous space station is crucial for sustaining India’s space exploration ambitions and securing its long-term strategic interests in space.

  2. India has achieved remarkable successes in unmanned space missions including the Chandrayaan and Mars Orbiter Mission, but has not ventured into manned space missions. What are the main obstacles to launching a manned space mission, both in terms of technology and logistics? Critically examine if it is worth the risk. (UPSC Mains 2017, GS-III)

    Answer Structure:

    • Introduction: Acknowledge India’s prowess in unmanned missions (Chandrayaan, MOM) and introduce the Gaganyaan mission as India’s first step towards manned spaceflight.
    • Obstacles to Manned Missions:
      • Technological Obstacles: Human-rated launch vehicle (requiring high reliability), crew escape system, life support systems, re-entry vehicle with thermal shields, space suit development.
      • Logistical Obstacles: Astronaut training, establishing mission control for human spaceflight, medical support, post-landing recovery operations.
      • Financial Obstacles: Manned missions are significantly more expensive than unmanned ones.
    • Critical Examination (Is it worth the risk?):
      • Arguments for (Worth the risk): National prestige, inspiration for youth (STEM education), technological spin-offs, strategic advantage, and paving the way for future long-duration space exploration.
      • Arguments against (Not worth the risk): High cost that could be used for other developmental priorities (poverty, health), inherent risk to human life, and the argument that robotic missions can achieve most scientific goals more cheaply and safely.
    • Conclusion: Conclude with a balanced view that while the risks and costs are high, the long-term strategic, scientific, and inspirational benefits of a manned space programme like Gaganyaan justify the endeavor, positioning India as a major space power.

  3. Discuss India’s achievements in the field of Space Science and Technology. How the application of this technology has helped India in its socio-economic development? (UPSC Mains 2016, GS-III)

    Answer Structure:

    • Introduction: Briefly outline the journey of the Indian space program from its humble beginnings under Vikram Sarabhai to its current status as a world leader.
    • Achievements in Space Science and Technology:
      • Launch Vehicles: Development from SLV, ASLV to the workhorses PSLV and the powerful GSLV with an indigenous cryogenic engine.
      • Satellites: Expertise in building remote sensing (IRS, RISAT), communication (INSAT, GSAT), and navigation (IRNSS/NavIC) satellites.
      • Space Exploration: Landmark missions like Chandrayaan-1 (discovery of water molecules on the moon), Mars Orbiter Mission (MOM - first country to succeed in the first attempt), and Chandrayaan-3 (first to land on the lunar south pole).
    • Application in Socio-economic Development:
      • Agriculture: Crop acreage and production estimation, soil moisture data.
      • Disaster Management: Cyclone warning, flood mapping, drought assessment.
      • Resource Management: Forest cover monitoring, groundwater targeting, mineral prospecting.
      • Communication: Tele-education, telemedicine, banking (VSATs), Direct-to-Home (DTH) services.
      • Governance: Infrastructure planning, fishery advisories (potential fishing zones).
    • Conclusion: Conclude by summarizing that ISRO has not only achieved technological excellence but has remained true to its founding vision of using space technology for national development and the upliftment of the common person.

  4. What is the Kessler Syndrome with reference to space debris? Discuss the challenges and measures to mitigate it. (Hypothetical, based on syllabus trends)

    Answer Structure:

    • Introduction: Define space debris and its origins. Introduce the Kessler Syndrome as a theoretical scenario proposed by Donald J. Kessler in 1978.
    • Explain Kessler Syndrome:
      • Describe the core concept: a cascading chain reaction of collisions in a densely populated orbit (like LEO).
      • Explain that once the density of objects reaches a critical point, a collision can create a cloud of debris, which in turn increases the probability of further collisions, leading to a self-sustaining cascade.
      • Mention the potential outcome: rendering certain orbits unusable for generations.
    • Challenges in Mitigation:
      • Technological: Difficulty in tracking small debris, high cost and complexity of active debris removal (ADR) technologies.
      • Legal/Political: Lack of a binding international treaty on debris removal, issues of sovereignty over space objects (a country’s defunct satellite is still its property).
      • Economic: No clear business case for private companies to invest in debris removal.
    • Mitigation Measures:
      • Passive Measures (Prevention): Spacecraft design to minimize debris release, passivation of spent rocket stages (venting leftover fuel), de-orbiting satellites at the end of their life (e.g., the 25-year rule).
      • Active Measures (Removal): Developing technologies like nets, harpoons, robotic arms for Active Debris Removal (ADR). Mention projects like ESA’s ClearSpace-1.
      • Regulatory/International Cooperation: Strengthening guidelines through bodies like the Inter-Agency Space Debris Coordination Committee (IADC) and UNCOPUOS. Promoting global space situational awareness data sharing.
    • Conclusion: Emphasize that space debris is a global problem requiring a collaborative global solution, combining technological innovation with robust international legal frameworks to ensure the long-term sustainability of space activities.

  5. Critically analyze the role of the International Telecommunication Union (ITU) in the management of orbital resources. Is its framework adequate to handle the challenges posed by large satellite constellations? (Hypothetical, based on syllabus trends)

    Answer Structure:

    • Introduction: Introduce the ITU as a specialized UN agency and its mandate to regulate the radio-frequency spectrum and satellite orbits to avoid harmful interference.
    • Role of the ITU:
      • Allocation: Manages the geostationary orbit (GEO) as a limited resource, allocating orbital slots to nations.
      • Coordination: Maintains a Master International Frequency Register, providing a framework for countries to coordinate their satellite filings and prevent frequency interference.
      • Standardization: Develops technical standards that ensure networks and technologies seamlessly interconnect.
    • Analysis of its Framework:
      • Strengths: Has successfully prevented major conflicts over GEO slots and spectrum for decades; operates on a principle of international consensus.
      • Weaknesses/Inadequacies for Mega-Constellations:
        • ‘First-come, first-served’ Filing System: Favors entities with the resources to file for thousands of satellites, potentially warehousing orbital space and spectrum.
        • Focus on Interference, Not Debris: ITU’s mandate is primarily technical (radio interference), not physical (collision risk or debris). It doesn’t regulate the number of satellites in LEO.
        • Pace of Regulation: The four-year cycle of the World Radiocommunication Conference (WRC) is too slow to keep up with the rapid deployment of constellations like Starlink.
        • Enforcement: The ITU lacks strong enforcement mechanisms against non-compliance.
    • Conclusion: Conclude that while the ITU has been effective for traditional satellite systems, its current framework is being stretched to its limits by the new space race in LEO. There is a pressing need for the international community to either expand ITU’s mandate or develop new governance mechanisms to address the challenges of orbital crowding and space sustainability in the era of mega-constellations.

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