GSLV: Geosynchronous Satellite Launch Vehicle

What is GSLV? What are the variants of GSLV? What are the differences between GSLV and PSLV? Read here to know more.

Geosynchronous Satellite Launch Vehicle (GSLV) and Polar Satellite Launch Vehicle (PSLV) are two operational launch vehicles of India. They are used to carry spacecraft into space.

Read more about GSLV in this article.

Also read about Small Satellite Launch Vehicle (SSLV) and Polar Satellite Launch Vehicle (PSLV).

What is GSLV?

The Indian Space Research Organization (ISRO) created the Geosynchronous Satellite Launch Vehicle (GSLV), a space launch vehicle used to place satellites and other spacecraft into geosynchronous transfer orbits. Polar Satellite Launch Vehicle can’t lift as much weight into orbit as like the Geosynchronous Satellite Launch Vehicle.

Variants

The GSLV Mark I and Mark II of the GSLV rocket family are versions that use the Russian Cryogenic Stage (CS) and the domestic Cryogenic Upper Stage (CUS), respectively. All GSLV launches have taken place from Sriharikota’s Satish Dhawan Space Center.

India’s largest launch vehicle, the Geosynchronous Satellite Launch Vehicle Mark II (GSLV Mk II), is currently in use. This three-stage, four-liquid strap-on launch vehicle is part of the fourth generation. The GSLV Mk II’s third stage is the locally built and flight-tested Cryogenic Upper Stage (CUS). The vehicle has won four times in a row starting in January 2014.

GSLV MkIII is a three-stage heavy lift launch vehicle created by ISRO that was selected to launch the Chandrayaan-2 satellite. The vehicle has a cryogenic upper stage, a core liquid booster, and two solid strap-ons.

• The GSLV Mk III is intended to deliver satellites in the 4-tonne class into Geosynchronous Transfer Orbit (GTO) or about 10 tonnes into Low Earth Orbit (LEO), which is rough twice as much as the GSLV Mk II’s capacity.
• The GSAT-19 satellite was successfully launched into orbit on June 5, 2017, from SDSC SHAR, Sriharikota, using the GSLV-Mk III-D1, the first developmental flight of the rocket.
• On November 14, 2018, Satish Dhawan Space Centre SHAR, Sriharikota, launched GSAT-29, a high throughput communication satellite, in GSLV MkIII-D2, the second developmental flight of the GSLV MkIII.
• India’s second lunar mission, Chandrayaan-2, was successfully launched into Earth parking orbit on July 22, 2019, from Satish Dhawan Space Centre SHAR, Sriharikota, by GSLV MkIII-M1.

GSLV-Mk II is the largest launch vehicle developed by India. The salient features of this launch vehicle are mentioned below:

1. It is a fourth-generation launch vehicle.
2. It has four liquid-engine strap-ons.
3. The first flight by GSLV was on 18th April 2001.
4. The capacity of payloads:
   • It can carry 2500 kgs INSAT class of communication satellites and place it to GTO.
   • It can carry 5000 kgs heavy satellites to multiple smaller satellites in LEO.
5. It has three stages

1. • First stage – The 138-tonne solid rocket motor is augmented by 4 liquid strap-ons.
   • Second stage – One Vikas engine is used in the second stage.
   • Third Stage – Developed under the Cryogenic Upper Stage Project (CUSP), the CE-7.5 is India’s first cryogenic engine, developed by the Liquid Propulsion Systems Centre.

Difference Between PSLV and GSLV

• The Polar Satellite Launch Vehicle (PSLV) and the Global Space Launch Vehicle (GSLV) are rockets used by ISRO to launch satellites into space (Geosynchronous Satellite Launch Vehicle). Earth-observation or “remote-sensing” satellites are to be launched by PSLV into Sun-Synchronous circular polar orbits at altitudes ranging from 600 to 900 kilometres.
• Remote sensing satellites travel in a pole-to-pole orbit around the Earth (at about 98 deg orbital-plane inclination). When there is no change in the angle between the satellite’s centre and the Sun throughout the orbit, the orbit is said to be sun-synchronous.
• Due to their sun-synchronism characteristics, which enable the satellite’s onboard camera to take pictures of the planet under the same sun-illumination conditions during each of its repeated passes over the same place on the ground, these orbits are frequently referred to as “Low Earth Orbits (LEO)”. The satellite can therefore be used to keep an eye on the planet’s resources.
• The PSLV is used to launch remote sensing satellites into Sun-synchronous polar orbits as well as spacecraft with lower lift-off masses, up to around 1400 kg, into the elliptical Geosynchronous Transfer Orbit (GTO).
• The first and third stages of the PSLV’s four-stage launch vehicle are propelled by solid rocket motors, and the second and fourth stages are propelled by liquid rocket engines. Additionally, strap-on motors are employed to increase the thrust that the first stage produces. The PSLV is available in a number of variations, including the core-alone version (PSLV-CA), PSLV-G, and PSLV-XL, depending on how many strap-on boosters are utilised.
• Launching communication satellites into geosynchronous transfer orbit, which is normally 250 x 36,000 km elliptical, is the primary task of the GSLV (GTO). By starting its internal onboard engines, the satellite in GTO is lifted to its ultimate destination, Geo-synchronous Earth orbit (GEO), which is approximately 36,000 km in altitude (and zero degrees inclination on the equatorial plane).

Summary:

1. The PSLV is older than the GSLV.
2. The GSLV has a much greater load capacity than the PSLV.
3. The GSLV use cryogenic fuel while the PSLV doesn’t.
4. The GSLV has three stages while the PSLV has four stages.
5. The GSLV has 4 liquid boosters while the PSLV has 6 solid boosters.
6. The PSLV is more reliable than the GSLV.

Article Written by: Remya