Polar Satellite Launch Vehicle

The Polar Satellite Launch Vehicle (PSLV) is one of the most successful and reliable launch vehicles developed by the Indian Space Research Organisation (ISRO). Designed primarily to place satellites into polar, sun-synchronous, and low Earth orbits (LEO), the PSLV has also demonstrated remarkable versatility by launching payloads into geostationary transfer orbits (GTO) and interplanetary trajectories. It has become the workhorse of India’s space programme, symbolising the nation’s technological maturity and self-reliance in satellite launch capability.

Background and Development

The development of the PSLV began in the early 1980s, following the successful completion of ISRO’s Satellite Launch Vehicle (SLV) and Augmented Satellite Launch Vehicle (ASLV) programmes. While these earlier vehicles enabled India to achieve basic launch capability, they were limited to small payloads and low orbits.
With the increasing demand for earth observation, meteorological, and communication satellites, India needed a more powerful and reliable launch system. The PSLV project was thus initiated to provide the capability to place 1,000–1,800 kg class satellites into sun-synchronous polar orbits, crucial for remote sensing missions.
The first developmental flight of PSLV took place on 20 September 1993 from the Satish Dhawan Space Centre (SDSC), Sriharikota. Though the mission experienced partial failure, subsequent launches achieved high success rates, establishing PSLV as one of the world’s most dependable space launch vehicles.

Design and Technical Configuration

The PSLV is a four-stage launch vehicle that combines both solid and liquid propulsion systems, providing an optimal balance between thrust and control.

1. First Stage (PS1 – Solid Propellant Stage):
   • Equipped with a large solid rocket motor using hydroxyl-terminated polybutadiene (HTPB) as fuel.
   • Augmented by six strap-on boosters (either solid or liquid, depending on the variant) to provide additional lift-off thrust.
2. Second Stage (PS2 – Liquid Propellant Stage):
   • Powered by the Vikas engine, which uses unsymmetrical dimethylhydrazine (UDMH) as fuel and nitrogen tetroxide (N₂O₄) as oxidiser.
   • Provides high control precision and flexibility in orbital insertion.
3. Third Stage (PS3 – Solid Propellant Stage):
   • Uses HTPB-based solid fuel to propel the vehicle through the upper atmosphere.
4. Fourth Stage (PS4 – Liquid Propellant Stage):
   • Employs twin liquid engines using monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON-3).
   • Responsible for fine-tuning the orbit and deploying multiple payloads with precision.

The total height of the PSLV is about 44 metres, with a lift-off mass of around 320 tonnes (depending on configuration).

Variants of PSLV

To accommodate different mission requirements, ISRO has developed several variants of the PSLV:

• PSLV-G (Standard Version): The original configuration used for early missions, capable of launching satellites weighing up to 1,200 kg to sun-synchronous orbit.
• PSLV-CA (Core Alone): A simplified version without strap-on boosters, designed for lighter payloads.
• PSLV-XL: The most powerful version, with six extended strap-on boosters carrying more propellant. This variant has been used for major missions such as Chandrayaan-1, Mangalyaan, and IRNSS (NavIC) satellites.
• PSLV-DL/QL: Modernised configurations with two or four strap-on boosters, offering flexibility for medium-weight payloads.

Launch Sites and Infrastructure

All PSLV launches are conducted from the Satish Dhawan Space Centre (SDSC) SHAR on Sriharikota Island, off the coast of Andhra Pradesh. The facility includes:

• First Launch Pad (FLP) and Second Launch Pad (SLP) for vehicle integration and assembly.
• Advanced ground tracking and telemetry systems.
• Mission control facilities that coordinate all launch operations.

Notable Missions and Achievements

The PSLV has achieved numerous historic milestones in India’s space journey:

• PSLV-D2 (1994): First fully successful flight, placing IRS-P2 into orbit.
• PSLV-C2 (1999): First commercial launch, carrying India’s IRS-P4 (Oceansat-1) and two foreign satellites.
• PSLV-C11 (2008): Launched Chandrayaan-1, India’s first lunar mission.
• PSLV-C25 (2013): Launched Mars Orbiter Mission (Mangalyaan), making India the first Asian country to reach Mars orbit and the first in the world to do so on its maiden attempt.
• PSLV-C37 (2017): Set a world record by launching 104 satellites in a single mission, including 101 foreign satellites.
• PSLV-C45 (2019): Launched EMISAT and 28 customer satellites, showcasing complex multi-orbit capabilities.
• PSLV-C54 (2022): Successfully launched EOS-06 (Oceansat-3) and eight nano-satellites.

Through these missions, PSLV has launched over 380 satellites for 30+ countries, establishing India as a leading player in the global space launch market.

Role in India’s Space Programme

The PSLV has served as the backbone of ISRO’s Earth observation and remote sensing missions, launching satellites from the IRS (Indian Remote Sensing) and Cartosat series that provide critical data for agriculture, urban planning, disaster management, and defence applications.
It has also been instrumental in launching India’s navigation system (NavIC) satellites and interplanetary missions, thereby expanding India’s technological frontiers beyond Earth’s orbit.

Advantages and Technological Strengths

• High Reliability: PSLV has achieved one of the highest success rates globally, with over 95% mission success.
• Versatility: Capable of launching multiple payloads of varying sizes into different orbits during a single mission.
• Cost-Effectiveness: Its relatively low launch cost makes it highly competitive in the global satellite launch industry.
• Commercial Viability: Through Antrix Corporation Limited (ISRO’s commercial arm) and later NewSpace India Limited (NSIL), PSLV has become a preferred vehicle for launching foreign satellites.

International Collaboration and Commercial Launches

The PSLV’s reliability has made it a favoured choice for international customers, including agencies and organisations from the USA, UK, Canada, Germany, South Korea, Singapore, and Israel. India’s collaboration with global partners has positioned PSLV as a commercial launch platform, generating valuable revenue and international recognition for ISRO.

Future Prospects

Although PSLV continues to be operational, it is gradually being complemented by newer launch vehicles such as the Small Satellite Launch Vehicle (SSLV) for lighter payloads and the GSLV Mk III (LVM3) for heavier missions. However, PSLV remains vital for its proven design, multi-orbit flexibility, and cost efficiency.
ISRO is also upgrading PSLV technology for reusability and semi-cryogenic propulsion, aiming to improve efficiency and turnaround time for launches.

Significance and Legacy

The PSLV holds a special place in India’s scientific and technological history. It represents:

• The transition from dependence to self-reliance in space technology.
• India’s emergence as a reliable space power with global credibility.
• A platform that has enabled major scientific, defence, and commercial missions.

The PSLV’s success story reflects decades of innovation, perseverance, and engineering excellence. It stands as a symbol of “Make in India” in its truest sense — conceived, designed, and perfected by Indian scientists and engineers.