PSLV

What is PSLV?

The Polar Satellite Launch Vehicle (PSLV) is India's workhorse rocket, developed by the Indian Space Research Organisation (ISRO). First launched on 20 September 1993 (D1 mission — unsuccessful), PSLV achieved its first successful flight on 15 October 1994 (PSLV-D2). It is an expendable, four-stage launch vehicle that uses alternating solid and liquid propulsion — a unique design among global launch vehicles.

PSLV was originally designed to place Indian Remote Sensing (IRS) satellites into Sun-Synchronous Polar Orbits (SSPO) at 600-900 km altitude. Over the decades, it has become a versatile and highly reliable vehicle, used for launching satellites into polar, geosynchronous transfer, and even interplanetary orbits. PSLV launched India's historic missions: Chandrayaan-1 (2008) to the Moon and Mars Orbiter Mission (Mangalyaan, 2013) to Mars.

With over 60 missions to date and a success rate exceeding 95%, PSLV is one of the most reliable launch vehicles globally. NewSpace India Limited (NSIL) now manages PSLV production and commercial launches, with private sector consortium support.

How PSLV Works — Four-Stage Architecture

PSLV's unique design alternates between solid and liquid propulsion across four stages. Stage 1 (S139): The largest solid rocket motor in India, with one of the largest solid boosters globally, producing ~4,800 kN thrust. In the XL variant, six extended PSOM-XL strap-on boosters (each with 12.2 tonnes of solid propellant) augment first-stage thrust. Stage 2 (PS2): Uses the Vikas liquid engine (derived from French Viking engine), burning UH25 fuel with nitrogen tetroxide oxidiser, producing 799 kN thrust. Stage 3 (PS3): A solid rocket motor with 7.6 tonnes of HTPB-based propellant. Stage 4 (PS4): Two liquid engines using monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON), providing precise orbital insertion with restart capability.

The fourth stage's restart capability enables PSLV to inject satellites into multiple orbits in a single mission and has been repurposed as the PSLV Orbital Experimental Module (POEM) for in-orbit experiments.

Key Features

Current Status / Latest Data

• Total Missions: Over 60 launches since 1993; success rate above 95%.
• PSLV-C61 Failure (May 2025): Launched on 18 May 2025; failed approximately 8 minutes into flight due to a sudden drop in third-stage chamber pressure, leaving the EOS-09 radar imaging satellite in an unusable orbit — a rare failure for the workhorse.
• Return to Flight — PSLV-C62 (January 2026): Successfully launched on 12 January 2026 from Sriharikota, placing the EOS-N1 Earth observation satellite into orbit, marking PSLV's comeback after the C61 setback.
• Upcoming Missions (2026): PSLV-C63 carrying TDS-01 (Technology Demonstrator Satellite) and PSLV-N1 with Oceansat-3A (EOS-10) planned for Q1 2026.
• Engine Upgrades (April 2025): Modified engines tested at IPRC, expected to increase payload capacity by 15 kg.
• PSLV-Orbital Experimental Module (POEM): The fourth stage is reused as an orbital platform for in-orbit experiments — a cost-effective innovation.
• Foreign Satellite Launches: PSLV has launched over 340 foreign satellites from 36 countries, generating significant revenue through NSIL.

UPSC Exam Corner

Prelims: Key Facts

• PSLV: four-stage vehicle with alternating solid and liquid propulsion
• First successful launch: 15 October 1994 (PSLV-D2)
• Payload to 600 km SSPO: 1,750 kg
• Variants: PSLV-G, CA, DL, QL, XL (XL is most powerful with 6 strap-on boosters)
• Launched Chandrayaan-1 (2008) and Mars Orbiter Mission (2013)
• World record: PSLV-C37 launched 104 satellites in a single mission (15 February 2017)
• POEM: Fourth stage reused as orbital experimental platform
• Commercial launches managed by NSIL (NewSpace India Limited)
• S1: solid; S2: liquid (Vikas engine); S3: solid; S4: liquid (twin engines)
• PSLV-C61 failure: May 2025 (third-stage chamber pressure drop)
• PSLV-C62 return to flight: 12 January 2026 (EOS-N1 satellite)
• Foreign satellites launched: over 340 from 36 countries
• Height: 44 metres; XL variant weight: ~320 tonnes

Mains: Probable Themes

1. "PSLV has been the backbone of India's space programme. Evaluate its contribution and future relevance."
2. "Discuss India's commercial space launch capabilities and the role of PSLV in the global launch market."
3. "Analyse the significance of the PSLV-Orbital Experimental Module (POEM) as a low-cost space platform."
4. "How has ISRO's approach to incremental improvement of PSLV ensured mission reliability over three decades?"
5. "With the advent of SSLV and private launch vehicles, examine the future of PSLV in India's space ecosystem."

Sources: ISRO — PSLV Official | ISRO — List of PSLV Launches | Business Today — PSLV-C62 Return to Flight | NSIL — PSLV Production