GS Notes

Science and Technology Notes 01

12 min read

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.

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