LAUNCH VEHICLES
Science
INTRODUCTION
Launch Vehicles or Launchers are rockets used to carry satellites or spacecraft from the Earth’s surface into space. India has developed indigenous launch vehicle technology under the leadership of ISRO. The Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, is the primary centre responsible for the design and development of launch vehicles.
India currently operates two major launch vehicles:
• Polar Satellite Launch Vehicle (PSLV)
• Geosynchronous Satellite Launch Vehicle (GSLV)
HISTORICAL EVOLUTION OF INDIAN LAUNCH VEHICLES
1. Satellite Launch Vehicle – 3 (SLV-3)
• India’s first experimental satellite launch vehicle
• All-solid, four-stage rocket
• Payload capacity: 40 kg into Low Earth Orbit (LEO)
• First successful launch: Rohini Satellite on 18 July 1980
• Launch site: Sriharikota
• Made India the sixth nation capable of launching satellites independently
2. Augmented Satellite Launch Vehicle (ASLV)
• Developed to enhance payload capacity over SLV-3
• Payload capacity: 150 kg to LEO
• Operational during late 1980s
• Served as a technology demonstrator for advanced guidance, control and staging
• Acted as a bridge between SLV-3 and PSLV
POLAR SATELLITE LAUNCH VEHICLE (PSLV)
Overview
• Third generation Indian launch vehicle
• First Indian launcher to use liquid propulsion stages
• Expendable launch vehicle (used only once)
• Developed by ISRO primarily to launch Indian Remote Sensing (IRS) satellites
Structure and Stages
PSLV has four stages:
• First Stage (PS1): Solid propellant S139 motor
• Second Stage (PS2): Liquid propellant Vikas engine
• Third Stage (PS3): Solid rocket motor
• Fourth Stage (PS4): Twin liquid engines using earth-storable propellants
Capabilities and Uses
• Capable of launching satellites into LEO, Polar Orbit and Sun-Synchronous Orbit
• Used for launching small satellites and commercial payloads
• Successfully launched Chandrayaan-1 (2008) and Mars Orbiter Mission (2013)
Significance of PSLV
• Known as the “workhorse” of ISRO
• High reliability with long success streak
• Major contributor to ISRO’s commercial launch services
• Cost-effective satellite launch platform
Limitations of PSLV
• Payload capacity limited to about 1,500 kg
• Cannot launch heavy communication satellites into GTO
• Dependence on GSLV or foreign launchers for heavier payloads
GEOSYNCHRONOUS SATELLITE LAUNCH VEHICLE (GSLV)
Overview
• Fourth generation Indian launch vehicle
• Designed to launch heavy communication satellites into Geosynchronous Transfer Orbit (GTO)
• Three-stage vehicle with four liquid strap-on boosters
Structure
• First Stage: Solid core stage with four liquid strap-on boosters (Vikas engines)
• Second Stage: Liquid propellant stage
• Third Stage: Indigenous Cryogenic Upper Stage (CUS)
Significance of GSLV
• Enables independent launch of communication satellites
• Reduces dependence on foreign launch services
• Saves foreign exchange
• Strategic importance for national security and space autonomy
GEOSYNCHRONOUS SATELLITE LAUNCH VEHICLE MARK III (LVM3)
Overview
• Heaviest and most powerful Indian launch vehicle
• Three-stage configuration
• Designed for heavier satellites and human spaceflight missions
Stages
• First Stage: Two S200 solid strap-on boosters
• Second Stage: L110 liquid core stage
• Third Stage: C25 cryogenic upper stage (LOX–LH2)
Capabilities
• Can place 4-tonne satellite into GTO
• Can place 10-tonne payload into LEO
• Backbone of Gaganyaan human spaceflight programme
Importance
• Makes India fully self-reliant in heavy satellite launches
• Enhances India’s position in global launch market
• Supports interplanetary missions
WHY CRYOGENIC UPPER STAGE IS IMPORTANT
• Cryogenic engines provide much higher thrust efficiency
• Required for launching heavy payloads
• Uses liquid hydrogen and liquid oxygen at extremely low temperatures
• Produces clean exhaust – only water vapour
CRYOGENIC ENGINE – KEY FEATURES
• Liquid Oxygen liquefies at -183°C
• Liquid Hydrogen liquefies at -253°C
• High specific impulse
• Turbo pumps operate at very high speeds
• Technologically complex due to thermal and material challenges
ISRO’s Cryogenic Upper Stage Project (CUSP)
• Initiated to replace imported Russian cryogenic engines
• Indigenous development enhanced strategic autonomy
• Main engine thrust: ~73.5 kN
• Burn duration: ~720 seconds
DIFFERENCE BETWEEN PSLV AND GSLV
PSLV
• Best suited for LEO and polar orbits
• Lower payload capacity
• Solid and liquid propulsion
• Highly reliable and economical
GSLV
• Designed for GTO missions
• Higher payload capacity
• Includes cryogenic stage
• Essential for communication satellites
REUSABLE LAUNCH VEHICLE – TECHNOLOGY DEMONSTRATOR (RLV-TD)
Overview
• Experimental winged vehicle developed by ISRO
• Combines features of aircraft and launch vehicles
• Aims to reduce cost of access to space
Objectives
• Test hypersonic flight
• Autonomous navigation and landing
• Reusable space transportation technology
Future Vision
• To become first stage of a two-stage reusable launch system
• Significant reduction in launch cost
• Boosts India’s long-term space ambitions
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Subject: Science
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