Launch Vehicles of ISRO

Launch Vehicles are used to transport and put satellite and spacecraft into space. Important launch vehicles of ISRO are SLV - Satellite Launch Vehicle, ASLV - Augmented Satellite Launch Vehicle, PSLV - Polar Satellite Launch Vehicle and GSLV - Geosynchronous Satellite Launch Vehicle.

Reusable Launch Vehicle - Technology Demonstration Program (RLV - TD)

Satellites and space stations are launched into space by being attached to a launch vehicle. Rockets are the vehicles used for satellite launch. Normal launch vehicles are destroyed once they are used. They cannot be reused. If any part of the rocket can be recovered, that part can be repaired and used again. There is no fully reusable launch vehicle at present. Only any part that has been landed on the ground, like an airplane, can be used. America's Falcon 9 Full Thrust Rocket and India's RLV - TD Rocket are reusable rockets. ISRO launched the RLV - TD rocket on 23 May 2016. RLV - TD is India's first reusable launch vehicle. In the first test, the vehicle was re-launched in water. ISRO is currently trying to conduct tests to land reusable rockets. 

Scramjet Engine Technology Demonstator

Supersonic jet aircraft are aircraft that fly faster than the speed of sound. Scramjet is a supersonic jet aircraft. Scramjet engines are a new model in the ramjet category. The full form of scramjet is supersonic combustion ramjet. Unlike ramjets, they fly in air at supersonic speeds. Therefore, scramjets are able to achieve better speed and power. The scramjet engine, which is used for military purposes, was first successfully tested by Russia. Later, in 1991, NASA and others developed scramjet engines. India is the fourth country to successfully test a scramjet after Russia, the United States and the European Space Agency.

SLV (Satellite Launch Vehicle)

SLV is the first vehicle of ISRO to successfully launch a satellite. The first launch mission of SLV-3 on 10 August 1979 failed, but the second mission on 18 July 1980 was successful. The Rohini (RS-1) satellite was successfully launched in this mission. SLV has conducted four launches. The fourth and last launch of SLV was on 17 April 1983. All four launches of SLV were from the Satish Dhawan Space Centre in Sriharikota.

ASLV (Augmented Satellite Launch Vehicle)

Most of the tests that preceded the PSLV rocket were carried out on ASLV. The first launch mission of ASLV, ASLV D1, on 24 March 1987, failed. The second mission, ASLV D2, failed and the third mission, ASLV D3, was partially successful. ASLV D4 was the first fully successful mission of ASLV. The launch was on 4 May 1994. ASLV D4 successfully launched the 106 kg SROSS C2 satellite. ASLV has carried out four launches. ASLV D4 was the fourth and final launch of SLV. All four launches of ASLV were from the Satish Dhawan Space Centre in Sriharikota.

Geosynchronous Satellite Launch Vehicle (GSLV)

GSLV is a launch vehicle capable of launching geosynchronous satellites into orbit. ISRO developed the GSLV rocket with the aim of launching communication satellites into geostationary orbit. Its full name is Geosynchronous Satellite Launch Vehicle. The first launch using GSLV took place on April 18, 2001. An experimental satellite named GSAT-1 was launched into orbit. The various launch vehicles of GSLV are GSLV Mark I, GSLV Mark II, and GSLV Mark III. Out of the 14 launches conducted in the other two vehicles except GSLV Mark III, four were failures till August 12, 2021. The satellites successfully launched by GSLV Mark I and GSLV Mark II are INSAT-4CR, EDUSAT, GSAT-1, GSAT-2, GSAT-14, GSAT-6, INSAT-3DR, GSAT-9, GSAT-6A, and GSAT-7A. GSLV Mark I is a rocket using Russian technology. It was used from 2001 to 2010.

GSLV Mark III

This rocket, which belongs to the GSLV category, is a three-stage launch vehicle. GSLV Mark III is a modified version of the GSLV rocket. With a higher carrying capacity than GSLV, Mark III will compete with the modern rocket of America's 'Falcon' 9. GSLV Mark III is a huge rocket with a height of 43.4 meters, a diameter of four meters and a weight of 6,40,000 kg. This rocket is capable of carrying payloads of 8000 kg and 4000 kg for two types of orbits. GSLV Mark III was first launched from Sriharikota on December 18, 2014. The first stage uses a solid-fuel engine, the second stage uses two liquid-fueled Vikas engines, and the third stage uses a cryogenic rocket engine called CE 20.

Small Satellite Launch Vehicle (SSLV)

The Small Satellite Launch Vehicle (SSLV) is a satellite launch vehicle designed by ISRO to place small satellites into low-Earth orbits. The Small Satellite Launch Vehicle can launch satellites weighing up to 500 kg into Earth orbit on a launch-on-demand basis. ISRO's first SSLV vehicle, SSLV-D1, was launched from the Satish Dhawan Space Centre in Sriharikota on 7 August 2022 but failed. SSLV's first mission was to launch the Earth observation satellite EOS-02 and 'Azaadi Sat', built by 750 girls from 75 government schools in the country. SSLV-D2, India's second indigenously built vehicle, was launched on February 10, 2023. SSLV-D2 successfully launched ISRO's EOS 07, US-based Antisys' Janus-1, and Chennai-based Space Kids' Azad Sat 2 into orbit.

PSLV (Polar Satellite Launch Vehicle)

The Polar Satellite Launch Vehicle is India's most trusted satellite launch vehicle. PSLV is ISRO's third-generation rocket. The PSLV is 44m tall, weighs 320 tonnes and has a payload capacity of 1750 kg. Out of 60 launches of PSLV till 30 December 2024, 57 have been successful. The first launch of PSLV was a failure. On October 15, 1994, PSLV successfully placed the satellite IRS P2 into a heliostatic orbit. Chandrayaan in 2008, Mangalyaan in 2013 and the Indian Navigation Satellite System (NAVIC) are also milestones in PSLV missions. PSLV (PSLV C37) is the first rocket in the world to complete 104 satellites in a single launch. PSLV uses solid fuel in the first and third stages and liquid fuel in the second and fourth stages. Recently, ISRO announced that it is withdrawing from the manufacturing of PSLV rockets. From now on, the manufacturing of PSLV will be handed over to the private sector. ISRO will only carry out testing and assembling.

Cryogenic Engine

Cryogenic fuels are manufactured using cryogenic technology. Liquid hydrogen and liquid oxygen are examples of cryogenic fuels. Liquid hydrogen is usually used as fuel in cryogenic engines in rockets. Hydrogen is cooled to -253 degrees Celsius and oxygen to -183 degrees Celsius and is used as fuel in cryogenic engines by converting it into a liquid. India is the sixth country to have successfully developed a cryogenic engine indigenously. The other countries that have developed cryogenic technology on their own are the United States, Japan, China, Russia and the European Space Agency. GSLV D5 is a geostationary satellite launch vehicle using a cryogenic engine developed by India. Its first launch was on 5 January 2014 from Sriharikota. The communication satellite GSAT-14 was launched.