Space Technology
Space technology involves the study and utilization of outer space for exploration, communication, navigation, and security. India has emerged as a global space power, led by ISRO and supported by a growing private sector ecosystem.
1. Fundamentals of Space Technology
Satellite Orbits & Space Physics
| Describe Low Earth Orbit (LEO) - altitude, velocity, and applications. | Low Earth Orbit (LEO): - Altitude Range: 180 to 2,000 km. - Characteristics: High velocity (~7.8 km/s) and low communication latency. - Applications: Earth observation (e.g., Cartosat), spy satellites, and space stations (e.g., ISS). |
| Describe Medium Earth Orbit (MEO) - altitude and primary applications. | Medium Earth Orbit (MEO): - Altitude Range: 2,000 to 35,786 km. - Applications: Navigational satellite constellations (e.g., GPS, Galileo) and regional positioning systems (e.g., NavIC in upper orbits). |
| Compare Geostationary (GEO) and Geosynchronous (GSO) orbits. State their altitude and applications. | GEO and GSO Orbits: - Altitude: Exactly ~35,786 km. - GEO (Geostationary): Circular orbit directly above Earth's equator; matching Earth's rotation speed, appearing fixed in the sky. - GSO (Geosynchronous): Orbital period matches Earth's rotation, but may be inclined, tracing a figure-eight path. - Applications: Telecommunications, direct-to-home (DTH) broadcasting, and meteorological forecasting (e.g., INSAT/GSAT series). |
| What is a Sun-Synchronous Orbit (SSO) and why is it preferred for remote sensing? | - Sun-Synchronous Orbit (SSO): A polar LEO where the satellite's orbital plane rotates at the same rate as the Earth's orbit around the Sun. This ensures the satellite passes over any given point at the exact same local mean solar time, providing constant sun illumination angles crucial for remote sensing photography. |
| Define Lagrange Points and state where Aditya-L1 is positioned. | - Lagrange Points: Five gravitationally stable positions in a two-body orbital system (e.g., Sun-Earth) where gravitational pull and centripetal forces balance out. Allows a spacecraft to remain in a fixed relative position with minimal fuel expenditure. Aditya-L1 orbits in a Halo Orbit around the L1 point. |
| Briefly explain the concepts of Theia, Jarosite, and Lunarcrete. | Space Terminology in News: - Theia: A Mars-sized protoplanet hypothesized to have collided with the proto-Earth ~4.5 billion years ago, ejecting debris that formed the Moon. - Jarosite: An iron-sulfate mineral discovered on Mars, indicating the presence of acidic, sulfate-rich liquid water in Martian history. - Lunarcrete (Moon concrete): An aggregate material composed of lunar regolith and sulfur, designed to construct lunar bases without using water. |
Satellite Orbits: Visualized
Engine Types, Propulsion & Fuels
| Explain the chemistry and complexity of Cryogenic Engines. Give an Indian example. | - Cryogenic Engine: Uses super-cooled liquid oxygen (LOX) at -183°C as the oxidizer and liquid hydrogen (LH2) at -253°C as fuel. Provides the highest specific impulse (efficiency) for heavy-lift upper stages, but requires complex plumbing and metallurgy. E.g., ISRO's CE-20 cryogenic engine. |
| What is a Semi-Cryogenic Engine and its benefit? | - Semi-Cryogenic Engine: Replaces liquid hydrogen with refined kerosene (known in India as Isrosene) as fuel, while retaining liquid oxygen as the oxidizer. Benefits: Fuel is stable at room temperature, making the rocket more compact, cheaper, and easier to handle on the launchpad. |
| Differentiate between Ramjet and Scramjet engines. | Air-Breathing Engines: - Ramjet Engine: Compresses incoming air using the vehicle's forward speed (without a rotary compressor) for combustion. Works only at supersonic speeds (Mach 3–6). - Scramjet (Supersonic Combustion Ramjet): Airflow passing through the combustion chamber remains supersonic, enabling flight at hypersonic speeds (Mach 5+). |
| Compare Solid and Liquid rocket propellants. Give Indian examples. | Propellant States: - Solid Fuel: Delivers high thrust, simple storage, and does not require complex pumps. Once ignited, it cannot be throttled or shut off. E.g., PSLV's S139 first-stage booster. - Liquid Fuel: Fully throttlable, restartable, and controllable. E.g., Vikas Engine (liquid-fueled stage on PSLV, GSLV, and LVM3). |
ISRO's Launch Vehicle Fleet
| Detail the Small Satellite Launch Vehicle (SSLV) - stages, payload, and operational milestone. | - SSLV: A 3-stage, solid-fueled launch vehicle designed for low-cost, rapid integration (within 72 hours) of small satellites. Can place sub-500 kg payloads into LEO. Became fully operational after the successful EOS-08 launch (SSLV-D3). |
| Detail the Polar Satellite Launch Vehicle (PSLV) - stage sequence and famous missions. | - PSLV: A 4-stage launch vehicle with alternating solid and liquid propulsion stages (Stage 1 & 3: Solid; Stage 2 & 4: Liquid). Known as ISRO's "workhorse"; launched Chandrayaan-1, Mars Orbiter Mission, and the Cartosat/Resourcesat series. |
| Compare GSLV Mk II and LVM3 (GSLV Mk III) in terms of stages and payload capacities. | GSLV Fleet: - GSLV Mk II: A 3-stage vehicle with an indigenous cryogenic upper stage. Can carry ~2,500 kg to Geostationary Transfer Orbit (GTO). - LVM3: A 3-stage heavy-lift vehicle (featuring 2 solid strap-ons, a liquid core, and a high-thrust cryogenic upper stage). Can place 4,000 kg into GTO. Used for Chandrayaan-3 and the Gaganyaan program. |
| Explain the features of the upcoming Next Generation Launch Vehicle (NGLV) and the Reusable Launch Vehicle (RLV-TD) projects. | Future Vehicles: - NGLV (Soorya): A under-development heavy-lift, 3-stage semi-cryogenic launcher designed with a reusable first stage, reducing launch costs. - RLV-TD (Reusable Launch Vehicle): A space shuttle-shaped testbed. Successfully completed autonomous runway landing experiments (LEX) in Karnataka. |
Launch Site Physics: Why Sriharikota?
| Why are spaceports located on the East Coast close to the equator? | Equatorial East Coast Advantage: - Rotational Boost: Sriharikota is situated close to the equator. Launching eastward allows rockets to harness Earth's tangential rotation speed (~450 m/s), saving fuel. - Safety Corridor: Eastward launches fly directly over the Bay of Bengal, ensuring that spent boosters and debris fall safely into the ocean without threatening human settlements. |
| What is a dogleg maneuver, and how does it affect SHAR polar launches? | - Dogleg Maneuver: A curved flight trajectory used to prevent a rocket from flying over populated territories during launch. For polar launches from SHAR, the rocket must steer around Sri Lanka, which consumes extra propellant and reduces the maximum payload weight. |
| Why is the new spaceport at Kulasekarapattinam being built? | - Kulasekarapattinam Spaceport: A new launch site in southern Tamil Nadu optimized for SSLV launches. Being further south, rockets can launch directly south into polar orbits without needing a dogleg maneuver around Sri Lanka, maximizing payload capabilities for small launchers. |
2. India's Landmark Space Missions
Lunar Exploration (Chandrayaan Program)
| Describe Chandrayaan-1 and its primary scientific discovery. | - Chandrayaan-1 (2008): India's first lunar orbiter mission launched via PSLV-C11. Its Moon Impact Probe (MIP) detected water molecules ($H_2O$) on the lunar surface, a major scientific breakthrough. |
| What were the components of Chandrayaan-2 and its outcome? | - Chandrayaan-2 (2019): Comprised an orbiter, lander (Vikram), and rover (Pragyan). The orbiter was successfully placed in a polar orbit and remains operational. However, the lander suffered a communications blackout and crashed during descent. |
| Detail Chandrayaan-3 - landing site, naming conventions, and rover findings. | - Chandrayaan-3 (2023): Successfully soft-landed near the Lunar South Pole (69.3°S) at a site named Shiva Shakti Point. The Pragyan rover confirmed the presence of elemental sulfur in lunar soil and analyzed surface soil temperatures. |
| Detail the goals of the planned Chandrayaan-4 and Chandrayaan-5 (LUPEX) missions. | Future Lunar Projects: - Chandrayaan-4: A lunar sample return mission planned to use a modular docking approach in Earth/Lunar orbits with two separate rocket launches. - Chandrayaan-5 (LUPEX): The Lunar Polar Exploration mission, a joint collaboration with Japan's JAXA, featuring an advanced rover designed to scout for subsurface water ice. |
Chandrayaan Evolution: Visualized
Planetary, Solar & Deep Space Missions
| Detail the achievements of the Mars Orbiter Mission (Mangalyaan). | - Mangalyaan (MOM - 2013): India's first interplanetary spacecraft, launched using a PSLV. Made India the first nation to successfully reach Mars orbit on its maiden attempt. Carried scientific payloads such as the Methane Sensor for Mars (MSM). |
| Explain the target orbit and scientific payloads of Aditya-L1. | Aditya-L1 (2023): India's first solar observatory. Located in a halo orbit around the Sun-Earth Lagrange Point 1 (L1) (approx. 1.5 million km from Earth). Key Payloads: - VELC (Visible Emission Line Coronagraph): Observes and maps the solar corona. - SUIT (Solar Ultraviolet Imaging Telescope): Images the solar photosphere and chromosphere. |
| Explain the unique capabilities of AstroSat and the goal of Shukrayaan-1. | Observatories & Future Projects: - AstroSat (2015): India's first multi-wavelength space observatory. It studies cosmic sources simultaneously in optical, ultraviolet, and X-ray bands. - Shukrayaan-1: A proposed Venus orbiter mission equipped with a Synthetic Aperture Radar (SAR) to penetrate Venusian clouds and map its surface. |
Gaganyaan & ISS Axiom-4 Missions
| Detail the objectives and components of India's Gaganyaan program. | Gaganyaan Program: A mission designed to demonstrate indigenous human spaceflight capability. It aims to send a 3-member crew into a 400 km orbit for 3 days and land them safely back in Indian waters. Components: - HLVM3: Human-rated LVM3 rocket. - Crew Module (CM): Double-walled pressurized crew compartment. - Service Module (SM): Houses power and propulsion systems. - Crew Escape System (CES): High-thrust escape system in case of emergency on the launchpad or ascent. |
| What is Vyommitra? | - Vyommitra: An indigenous, Sanskrit-speaking female half-humanoid robot (gynoid) developed by ISRO to fly aboard the uncrewed Gaganyaan test missions (G1/G2) to simulate crew functions and monitor cabin parameters. |
| What is the Axiom-4 mission and India's participation in it? | - Axiom-4 Mission (ISS): Wing Commander Shubhanshu Shukla is selected as the primary astronaut from ISRO to fly to the International Space Station aboard a SpaceX Crew Dragon capsule. Key scientific payloads include studies on microgravity-induced muscle wastage (myogenesis) and the resilient survival mechanisms of tardigrades. |
NISAR Project (NASA-ISRO SAR)
| Explain the concept, radar bands, and main objectives of the NISAR project. | NISAR (NASA-ISRO Synthetic Aperture Radar): - Partnership: A joint Earth-observing radar mission developed by NASA and ISRO. - Technology: The first radar mission to use two different radar frequencies: L-band (provided by NASA) and S-band (provided by ISRO) using a shared 12-meter reflector antenna. - Objective: To map the entire Earth's land and ice-covered surfaces every 12 days. It tracks changes in ecosystems, ice sheets, glacier velocities, and ground deformations (e.g., earthquakes, volcanic activity). |
3. Satellite Applications & Security
Satellite Navigation: NavIC & GAGAN
| Explain the purpose, orbital configuration, and atomic clocks of NavIC. | NavIC (IRNSS): - Purpose: India's independent regional satellite navigation system designed to provide real-time positioning data across India and up to 1,500 km outside its land borders. - Configuration: Formed by a constellation of 7 operational satellites (3 in Geostationary orbits and 4 in inclined Geosynchronous orbits). - Clocks: Equipped with ultra-stable Rubidium atomic clocks to determine precise positioning coordinates. |
| Differentiate between NavIC's services and describe the GAGAN system. | NavIC Services & GAGAN: - NavIC Services: Offers Standard Positioning Service (SPS) for civilian applications and Restricted Service (RS) which is encrypted for defense and military operations. - GAGAN: Developed by ISRO and the Airports Authority of India (AAI). It is a Satellite-Based Augmentation System (SBAS) that enhances the accuracy and reliability of GPS receiver signals over the Indian airspace, primarily for civil aviation navigation. |
Satellite Categorization & Mission Outcomes
| Categorize ISRO satellites based on their functional utilities, giving examples. | Satellite Types: - Communication Satellites: INSAT and GSAT series for telecommunications, television broadcasting, and search-and-rescue services. - Earth Observation (EO) Satellites: Cartosat (mapping), Risat (radar imaging), Resourcesat (land/water resources), and the EOS series. - Scientific & Experimental: AstroSat (astronomy), XPoSat (cosmic X-ray polarimetry), and PoEM (which turns PSLV's fourth stage into a stable orbital experiment platform). |
| Detail the success of EOS-08 and the failure of EOS-09 in recent missions. | Recent Mission Performance (2025): - EOS-08 (Success): Successfully launched on the SSLV-D3 flight, signifying the formal operationalization of the Small Satellite Launch Vehicle (SSLV). - EOS-09 (Failure): The PSLV-C61 flight failed to place the EOS-09 radar imaging satellite in orbit due to an unexpected pressure drop in the rocket's third-stage solid motor. |
4. Space Sustainability & Governance
Space Debris & Situational Awareness (NETRA)
| What is the Kessler Syndrome? | - Kessler Syndrome: A theoretical scenario proposed by NASA scientist Donald Kessler where the volume of space debris in LEO is so high that a collision between two objects initiates a chain reaction of subsequent collisions. This renders space operations and satellite communication impossible for generations. |
| Explain Project NETRA and the Digantra initiative. | Space Situational Awareness (SSA) in India: - Project NETRA (Network for Space Object Tracking and Analysis): ISRO's warning system to track space junk and active satellites, protecting Indian orbital assets from collision risks. - Digantra: An Indian space startup building a commercial space weather and space debris tracking network, including India's first commercial SSA observatory in Uttarakhand. |
| Detail Active Debris Removal (ADR) solutions and ISRO's Mission RISE. | Space Sustainability Solutions: - Laser Ablation: Targeting space debris with ground-based or space-based lasers to slightly slow them down, causing them to re-enter and burn up in the atmosphere. - Magnetic Claws/Nets: Capturing tumbling defunct satellites physically to guide them into destructive re-entry. - Mission RISE: ISRO's planned demonstration mission for in-orbit servicing, refueling, and life extension of existing satellites. |
Indian Space Institutional Framework
| Outline the institutional setup of the Indian space sector (ISRO and IN-SPACe). | Indian Space Architecture: - ISRO: The national R&D wing operating under the Department of Space (DoS), executing scientific exploration and technological developments. - IN-SPACe: An independent, single-window clearance agency created to facilitate, authorize, and regulate space activities conducted by private entities (Non-Governmental Entities - NGEs) in India. |
| Differentiate between the mandates of NSIL and Antrix. | Commercial Entities: - NSIL (NewSpace India Limited): The state-owned commercial arm of ISRO. It is tasked with scaling up industrial launch vehicle production (e.g., PSLV consortia) and commercializing ISRO technologies. - Antrix Corporation: ISRO's legacy commercial and marketing agency handling satellite launches for foreign clients. |
Space Governance: Visualized
International Space Legal Treaties
| Outline the Outer Space Treaty and the Space Liability Convention. | Space Law Treaties: - Outer Space Treaty (1967): The basic framework of international space law. Declares space exploration as a peaceful activity for all mankind; bans states from placing nuclear weapons or other weapons of mass destruction in orbit or establishing military bases on the Moon. - Liability Convention (1972): Mandates that a launching state is absolutely liable to pay financial compensation for damage caused by its space objects on the surface of the Earth or to aircraft in flight. |
| What are the Artemis Accords and India's association? | - Artemis Accords: A multilateral framework led by NASA defining principles for civil space exploration and resource utilization on the Moon, Mars, and beyond. India signed the accords in 2023. |
5. Astrophysics & Observatories in News
Key Scientific Infrastructure
| Briefly explain the significance of the Kodaikanal Solar Observatory and KM3NeT. | Scientific Infrastructure: - Kodaikanal Solar Observatory: Located in Tamil Nadu; completed 125 years of continuous solar physics observations in 2024. - KM3NeT: A large-scale European research infrastructure hosting deep-sea neutrino telescopes in the depths of the Mediterranean Sea. |
| Detail LignoSat and TSAT-1A. | Satellites in News: - LignoSat: A tiny experimental satellite made of magnolia wood, launched by Japanese researchers to test the viability of biodegradable materials in space, reducing toxic metallic debris during de-orbit burnup. - TSAT-1A: India's first sub-meter resolution optical satellite manufactured by the private Tata Advanced Systems Limited (TASL) for intelligence gathering. |
| What is the HOPE Analog Mission and why was Ladakh chosen? | - HOPE Analog Mission: A simulated space habitat mission conducted at Ladakh's Tso Kar Valley. The high altitude, low atmospheric pressure, high ultraviolet exposure, extreme cold, and saline dry permafrost replicate Martian environmental stress, allowing scientists to test life support systems. |
🎯 UPSC Prelims 2026 Questions & Explanations
| 1. The Indian National Space Promotion and Authorisation Centre (IN... | - Question 72: 1. The Indian National Space Promotion and Authorisation Centre (IN-SPACE) is an autonomous agency formed to facilitate participation of private entities. Which of the following statements with regard to drone swarms is/are correct? 1. They use Terahertz band of frequency to communicate with the command centre. 2. Individual drones in the swarm can communicate with other drones in the swarm. 3. GPS Spoofing is a commonly used technique to counter drone swarm attack. Select the answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 2 only (d) 1, 2 and 3 Correct Answer: (B) Key Concepts & Explanation: 2. Agnikul Cosmos launched the world's first flight using 3D-printed rocket engine. 3. Skyroot Aerospace has developed liquid fuel for GSLV. 4. Which of the statements given above is/are correct? The Indian National Space Promotion and Authorisation Centre (IN-SPACE) is an autonomous agency formed to facilitate participation of private entities: IN-SPACE was established in 2020 as a single-window autonomous agency to encourage, support, and authorize private sector participation in India's space activities. three three statements have been in the news in the three statements have been in the news e/technology/tech-news-technology/space-based-capabilities-pawan-goenka-chairman-in-space-10378689/https://indianex.com/article/technology/science/agnikul-carries-out-successful-sub-orbital-launch-of-agnibaan-rocket-9360673/https://indianex.com/article/e/india/skyroot-aerospace-vikram-1-orbital-rocket-launch-sriharikota-revanth-reddy-10655921/ EN Sandhan Test Series Recently, the government gave its approval for the formation of the 'Indian National Space Promotion and Authorisation Centre (IN-SPACE)'. PT 365 5.12.10 News-news-agency 2025-11-28/also-in-news-news- Drone swarms generally operate using conventional communication frequencies such as UHF, VHF, Wi-Fi, and other radio frequency bands rather than the Terahertz band, which remains largely experimental and is not used in practical drone swarm operations. A major characteristic of drone swarms is the ability of individual drones to communicate with one another through inter-drone communication protocols, enabling coordinated and decentralized functioning. GPS spoofing is also recognized as an important counter-drone technique in which false GPS signals are transmitted to disrupt drone navigation. They use the Terahertz band of frequency to communicate with the command centre: Drone swarms primarily rely on standard radio frequency bands such as UHF, VHF, and ISM bands for communication. Terahertz communication technology is still under development and has not been adopted for operational drone swarm systems. Hence, only statement 1 is incorrect. Individual drones in the swarm can Drones' emergence as the new front of aerial attack M FCA https://www.th.ehindu.com/news/national/chennai-bengaluru-among-airports-where-aircraft-encountered-gps-spoofing/article70346453.ecehttps://www.moneycontrol.com/drone-warfare-is-rapidly-moving-into-higher-frequency-bands-13926801.html RM Sandhan Test Series 'GPS Spoofing', sometimes seen in the news, is related to (a) improving the accuracy of global positioning systems for aviation. (b) disguising satellite signals to mislead navigation systems. (c) blocking GPS signals to prevent satellite surveillance. (d) enhancing cybersecurity in mobile communication networks. PT 365 2026 SnT: Article 5.9.13. CYBER ATTAC KS/SCA MSIN NEWS/le/2026-04-y https://vision/as.in/current/affairs/upsc/daily/news-summa/ry/article/2026-04-y Partial/system-could/worry/ Year Asked: Prelims 2026 |
High-Yield S&T Rapid Revision: Space & Satellite Tech
- Launch Vehicles:
- PSLV: Four-stage vehicle using solid-liquid-solid-liquid propulsion, optimized for sun-synchronous polar orbits (ISRO).
- GSLV Mk III (LVM3): Three-stage launch vehicle with solid rocket boosters, liquid core stage, and cryogenic upper stage, utilized for Chandrayaan-3 and Gaganyaan missions (ISRO).
- SSLV: Small Satellite Launch Vehicle designed for rapid turnaround launching of small satellites up to 500 kilograms (ISRO).
- Navigation: NavIC (IRNSS) constellation using seven satellites in geostationary and geosynchronous orbits, providing 1500 kilometers coverage around India (ISRO).
- Orbits: Low Earth Orbit (LEO) ranging from 200 to 2000 kilometers; Medium Earth Orbit (MEO) for navigation systems; Geostationary Earth Orbit (GEO) fixed at 35,786 kilometers above the equator (ISRO).
- Key Missions:
- Aditya-L1: Indian solar observatory placed in a halo orbit around the Lagrangian point L1 to study the solar corona (ISRO).
- Gaganyaan: Human spaceflight program targeting sending a three-member crew to a 400 kilometers orbit (ISRO).
- Mangalyaan (MOM): Mars Orbiter Mission, making India the first nation to reach Martian orbit on its maiden attempt (ISRO).