Satellite Launch Vehicles | Science & Technology for UPSC CSE PDF Download

Introduction

• Satellite Launch Vehicles are essential for space missions and for sending satellites into orbit. 
•  These vehicles, commonly referred to as rockets, are responsible for transporting satellites and other payloads into space. 
•  The Indian Space Research Organisation (ISRO) has made great strides in this field, significantly enhancing India's ability to explore space. 
•  ISRO's Satellite Launch Vehicles have been crucial in placing satellites into different orbits, which serve various purposes such as communication, earth observation, and scientific research. 

What are Launch Vehicles?

• A launch vehicle is a rocket-powered machine designed to carry a spacecraft beyond Earth's atmosphere, either into orbit around our planet or to other destinations in outer space. 
• Satellites play a crucial role in space missions, but they cannot reach space on their own. They depend on launch vehicles and powerful rockets to make their journey into the cosmos. 
• These launch vehicles are equipped with strong propulsion systems that produce the massive energy needed to overcome Earth's gravity and lift heavy payloads, such as satellites, into space. 
• The Indian Space Research Organisation (ISRO) began its journey into satellite launch vehicles with the Satellite Launch Vehicle (SLV) in 1980, which was India’s first experimental attempt at launching satellites into space. This was followed by the development of a more advanced Augmented Satellite Launch Vehicle (ASLV). 
• In 1994, ISRO successfully launched its first Polar Satellite Launch Vehicle (PSLV), marking a significant advancement in launch vehicle technology. 
• In 2001, ISRO further progressed by developing the Geosynchronous Satellite Launch Vehicle (GSLV), capable of carrying heavier satellites into Geosynchronous and Geostationary Orbits.

Working of Launch Vehicles

• Rocket Propulsion System: Launch vehicles rely on rocket propulsion, which is based on Newton's Third Law of Motion - for every action, there is an equal and opposite reaction. The propulsion system generates the force needed to lift the rocket off the ground.
• Multiple Stages: Launch vehicles are built with multiple stages that separate and fall away as the rocket ascends. Each stage has its own engines and propellant and is discarded when it is no longer needed, making the rocket lighter and more efficient.

• Fuel and Propellant: The propellant, a combination of fuel and oxidizer, is crucial for generating thrust. Common propellants include liquid hydrogen and liquid oxygen (LH2/LOX). 
• Guidance System: Launch vehicles are equipped with precise guidance and control systems to ensure they follow the correct trajectory into space.
• Payload Fairing: The payload, such as a satellite, is protected by a shell called the payload fairing during the initial stages of flight. This fairing shields the payload from aerodynamic forces and heat. Once the rocket reaches space, the fairing is jettisoned, exposing the payload for insertion into its intended orbit.

Retired Satellite Launch Vehicles of ISRO

• The SLV was India’s first experimental satellite launch vehicle, designed to place small payloads into Low Earth Orbit (LEO).
• It was a four-stage vehicle, all powered by solid fuel, capable of launching payloads weighing up to 40 kg into LEO.
• The first successful launch of the SLV took place on July 18, 1980, from Sriharikota, where it successfully placed the Rohini satellite (RS-1) into orbit.
• This achievement made India the sixth country in the world to develop and operate its own satellite launch vehicle.

Augmented Satellite Launch Vehicle (ASLV):

• Following the SLV, the ASLV was introduced and operated until the 1990s, paving the way for more advanced vehicles like the PSLV.
• The ASLV was a five-stage vehicle, also using solid propellant, designed to launch satellites weighing up to 150 kg into circular orbits at an altitude of 400 km.

Active Satellite Launch Vehicles of ISRO

• Polar Satellite Launch Vehicle (PSLV)
• Geosynchronous Satellite Launch Vehicle (GSLV)
• Geosynchronous Satellite Launch Vehicle Mk III (LVM3)

Sounding Rockets:

• Sounding rockets are used to explore the upper atmosphere and conduct space research. ISRO began launching these rockets in 1965, with the first one launched in 1963 marking the start of the Indian Space Programme. 
• The Rohini Sounding Rocket Programme, established in 1975, consolidated all sounding rocket activities. Currently, there are three operational versions of sounding rockets with varying payload capacities and apogees. 

Polar Satellite Launch Vehicle (PSLV):
Overview: India’s third-generation launch vehicle, first successfully launched in October 1994. 
Features: First Indian launch vehicle with liquid stages, capable of launching multiple satellites into different orbits. 
Stages:

•  First Stage: Solid rocket motor (S139). 
•  Second Stage: Earth-storable liquid rocket engine (Vikas engine). 
•  Third Stage: Solid rocket motor (S7) for high thrust. 
•  Fourth Stage: Two Earth-storable liquid engines. 

Variants: PSLV-XL, QL, and DL use strap-on motors for added thrust. Core-alone version (PSLV-CA) does not use strap-ons. 
Reliability: Known as “the workhorse of ISRO” for Low Earth Orbits (LEO). 
Payload Capacity: Up to 1,750 kg to 600 km altitude Sun-Synchronous Polar Orbits. 
Notable Launches: Chandrayaan-1 (2008), Mars Orbiter Spacecraft (2013). 

Geosynchronous Satellite Launch Vehicle (GSLV):
Overview: Fourth-generation launch vehicle designed for geostationary transfer orbit using a cryogenic third stage. 
Features: Three-stage vehicle with four liquid strap-ons. Initially used Russian cryogenic stages, later developed indigenously. 
Stages:

•  First Stage: Solid rocket motor (S139) with 4 liquid strap-ons. 
•  Second Stage: Vikas engine. 
•  Third Stage: Cryogenic Upper Stage. 

Payload Capacity: Up to 6 tonnes in Low Earth Orbits, 2,250 kg in Geosynchronous Transfer Orbit (GTO). 
Notable Launches: Communication satellites such as INSAT and GSAT. 

LVM3 (Geosynchronous Satellite Launch Vehicle Mk III):
Overview: Next-generation launch vehicle, previously known as GSLV MkIII. 
Features: Three-stage vehicle with two solid strap-on motors, one liquid core stage, and a high-thrust cryogenic upper stage. 
Stages:

•  Core Stage: S200 solid motor. 
•  Liquid Stage: Two Vikas engines. 
•  Cryogenic Upper Stage: Indigenous high-thrust cryogenic engine (CE20). 

Payload Capacity: Up to 4 tonnes into Geosynchronous Transfer Orbits, 8,000 kg into 600 km Low Earth Orbits. 
Notable Launches: Chandrayaan-3 mission. 

Satellite Launch Vehicles of ISRO Under Development 

Human Rated Launch Vehicle (HRLV):

•  A modified version of the current heavyweight LVM-3 launch vehicle. 
•  Capable of launching the Orbital Module into a 400 km Low Earth Orbit. 
•  Includes a Crew Escape System (CES) powered by quick-acting and high-burn rate solid motors. 

Small Satellite Launch Vehicle (SSLV):

•  A three-stage launch vehicle with three solid propulsion stages and a terminal stage based on liquid propulsion called the Velocity Trimming Module. 
•  Capable of launching nano, micro, and mini satellites up to 500 kg in a 500 km planar orbit. 

Reusable Launch Vehicle - Technology Demonstrator (RLV-TD):

•  Resembles an aircraft, combining the complexities of launch vehicles and airplanes. 
•  Comprises a nose cap, fuselage, two delta wings, and two vertical tails, along with active control surfaces like elevons and rudder. 
•  Future plans include scaling it up to become the first stage of India’s reusable two-stage orbital launch vehicle. 

Scramjet Engine - Technology Demonstrator (TD):

•  Operates at hypersonic speeds with supersonic combustion, using hydrogen as fuel and atmospheric oxygen as the oxidizer. 
•  The first experimental mission was successfully conducted in 2016, making India the fourth country to demonstrate flight testing of a scramjet engine. 

Notable Foreign Launch Vehicles Used by ISRO

• Ariane 5:. heavy-lift launcher used by the European Space Agency, capable of carrying over 20 metric tons to Low Earth Orbit (LEO) and more than 10 metric tons to Geostationary Transfer Orbit (GTO). India has used Ariane 5 for launching various communication and earth observation satellites, including INSAT-3D and GSAT-30.
• Falcon 9: The world’s first orbital-class reusable rocket designed and manufactured by SpaceX. Falcon 9 can launch payloads of 22 metric tons to LEO and 8 metric tons to GTO.
• Space Launch System (SLS):. super heavy-lift rocket developed by NASA, capable of launching 70 metric tons to LEO. SLS is the only rocket capable of transporting the Orion spacecraft, four astronauts, and large cargo to the Moon in a single mission. It includes crew and service modules and a launch abort system. 
• Soyuz 5: One of the heaviest launch vehicles from the Russian Space Agency, with the capability of launching 17 metric tons to LEO.