A History of India’s Launch Vehicles

From Sounding Rockets to Human Spaceflight

The story of India’s launch vehicle program is a narrative of self-reliance, methodical progress, and pragmatic ambition. From the humble beginnings of launching small sounding rockets from a coastal village, India has systematically built a domestic capacity that now includes placing heavy satellites into high orbits, sending robotic explorers to the Moon and Mars, and preparing for human spaceflight. This journey wasn’t a race against other nations; it was a deliberate, step-by-step development of technology driven by national needs, from weather forecasting and telecommunications to national security and scientific discovery.

The Dawn of an Ambition: The 1960s and 70s

The origins of the Indian space program are inseparable from its founding visionary, Dr. Vikram Sarabhai. In the early 1960s, a newly independent India was grappling with immense developmental challenges. Sarabhai championed the idea that space technology was not a luxury but a necessary tool for a developing nation. He believed satellites could provide powerful solutions for mass communication, education, and resource management.

This vision led to the formation of the Indian National Committee for Space Research (INCOSPAR) in 1962. The program’s first physical home was the Thumba Equatorial Rocket Launching Station (TERLS), established in a fishing village in Kerala. Its location on the Earth’s magnetic equator made it an ideal spot for atmospheric and ionospheric research.

On November 21, 1963, a small, two-stage sounding rocket, the Nike-Apache, was launched from TERLS. The rocket and its payload were supplied by the United States. This launch marked the beginning of India’s journey into space. Throughout the 1960s and 70s, the program focused on these sounding rockets, which don’t enter orbit but fly a high arc to study the upper atmosphere. This phase was about building a skilled workforce, understanding rocket propulsion, and establishing the basic infrastructure for a space program.

In 1969, these efforts were institutionalized with the creation of the Indian Space Research Organisation (ISRO). The Department of Space followed in 1972, bringing all space activities under a unified government body. The goal was clear: India needed its own satellites, and to be truly self-reliant, it needed its own rockets to launch them.

The First Steps to Orbit: The Satellite Launch Vehicle (SLV) Project

The 1970s were dedicated to making the leap from sub-orbital sounding rockets to a true orbital launcher. This project was named the Satellite Launch Vehicle (SLV), often referred to as SLV-3. It was a modest rocket by global standards, designed to place a satellite weighing about 40 kilograms into Low Earth Orbit (LEO).

The project was led by Dr. A. P. J. Abdul Kalam, who would later become the President of India. The SLV-3 was a four-stage vehicle, and in a key design choice, all four stages used solid-fuel propellants. Solid-fuel rockets are generally less complex to build and handle than liquid-fueled ones, though they can’t be throttled or shut down once ignited. For a first vehicle, it was a practical and logical choice.

The first launch attempt of the SLV-3, on August 10, 1979, was a failure. A faulty valve in the second-stage guidance system caused the rocket to tumble out of control and crash into the Bay of Bengal just over five minutes into its flight. The failure was a public setback, but for the engineering team, it was a source of invaluable data on what had gone wrong.

ISRO analyzed the failure, corrected the flaws, and prepared for a second attempt. On July 18, 1980, the SLV-3 E-02 mission lifted off from the Sriharikota launch pad. This time, all stages performed perfectly. The rocket successfully placed the 35-kg Rohini RS-1 satellite into orbit. With this single launch, India became only the seventh nation in the world capable of independently launching its own satellites.

The SLV-3 program had two more launches, one successful in 1981 and a final failure in 1983. Its mission was complete. It had proven the technology, trained a generation of rocket scientists, and given India its first foothold in space.

A Difficult Leap: The Augmented Satellite Launch Vehicle (ASLV)

With the SLV-3 mastered, ISRO looked to its next logical step: launching slightly heavier satellites. The Augmented Satellite Launch Vehicle (ASLV) was conceived as a low-cost “step-up” from the SLV-3. The design was intended to be an enhanced version of the SLV-3, using its core stages, but adding two strap-on boosters. These were essentially two additional first stages derived from the SLV-3’s own first stage, strapped to the side of the main rocket.

This configuration was designed to triple the payload capacity, enabling launches of 150-kg satellites. On paper, it seemed like a straightforward enhancement. In reality, it proved to be a complex engineering challenge.

The first launch of the ASLV, in 1987, failed. The vehicle tumbled out of control shortly after liftoff when the strap-on motors failed to ignite properly. The second attempt in 1988 also failed, this time due to severe aerodynamic stresses and control system problems.

The ASLV program faced intense public and political scrutiny. Two consecutive failures were a serious blow to ISRO’s morale and reputation. The rocket became known for its difficulties. However, the engineers at ISRO persevered. The failures of the ASLV, while painful, provided essential lessons in complex aerodynamics, strap-on booster technology, and advanced guidance systems. These were technologies that SLV-3, a simple single-stack rocket, had never tested.

After a long pause to re-engineer the vehicle, ISRO launched the ASLV-D3 in 1992, which was a partial success, placing its satellite into a lower-than-intended orbit. Finally, in 1994, the ASLV-D4 mission was a complete success. By this time the ASLV program had been technologically and programmatically overtaken. Its value wasn’t in the satellites it launched, but in the lessons it taught. Those hard-won lessons were being channeled directly into a much larger, more ambitious project that would come to define ISRO for decades: the PSLV.

The Workhorse of India: The Polar Satellite Launch Vehicle (PSLV)

While the ASLV was struggling, ISRO’s main efforts were focused on developing a far more capable and versatile rocket: the Polar Satellite Launch Vehicle (PSLV). The design goals for PSLV were ambitious. It needed to be able to launch India’s 1-tonne class Indian Remote Sensing (IRS) satellites into a Sun-synchronous orbit (SSO). This is a special type of polar orbit where the satellite passes over the same part of the Earth at the same local solar time every day, which is extremely useful for Earth observation.

The PSLV was a completely new design and a massive leap in technology for ISRO. It was not a simple solid-fuel rocket. It featured a complex, four-stage design that mixed both solid and liquid propellants:

• First Stage (PS1): A massive solid-fuel motor, one of the largest in the world at the time, augmented by six strap-on boosters.
• Second Stage (PS2): A liquid-fueled stage, powered by the newly developed Vikas engine. The Vikas engine, based on a French design, would become a reliable mainstay of Indian rocketry.
• Third Stage (PS3): A solid-fuel motor for the upper-atmosphere phase of the flight.
• Fourth Stage (PS4): A smaller, liquid-fueled upper stage with two engines, designed for the precise injection of the satellite into its final orbit.

This hybrid design gave the PSLV both high thrust at liftoff (from the solids) and high precision in orbit (from the liquids).

Like its predecessors, the PSLV’s first flight was a failure. In September 1993, the PSLV-D1 mission failed when a software error in the guidance system caused the rocket to lose control after the second stage separated. The rocket and its satellite fell into the sea.

ISRO’s response was characteristic. The team identified the software bug, corrected it, and strengthened the vehicle’s control systems. Just over a year later, in October 1994, the PSLV-D2 lifted off and flawlessly placed its satellite into the intended orbit. This was the true beginning of India’s modern space program.

A Rocket for All Missions: PSLV Variants

Following its initial success, the PSLV quickly proved its reliability. ISRO began to iterate on the design, creating a family of rockets to serve different mission needs:

• PSLV-G (Generic): The original 1990s configuration with six standard strap-on boosters.
• PSLV-CA (Core Alone): A lighter version with no strap-on boosters at all. This is used for smaller satellites or missions requiring less power.
• PSLV-XL (Extended): The high-performance model. This variant uses six larger, more powerful “extended” strap-on boosters, significantly increasing its lift capacity.

This flexibility allowed ISRO to “right-size” the rocket for the mission, from launching a single large satellite to carrying dozens of small ones.

The Missions That Defined a Nation

The PSLV’s reliability became legendary. After its first failure, it compiled a streak of dozens of successful launches. It became ISRO’s “workhorse,” trusted with India’s most important scientific, military, and commercial payloads. Its success built India’s reputation as a cost-effective and dependable launch provider on the world stage.

Two missions, in particular, demonstrated the PSLV’s capability beyond simple Earth orbit:

1. Chandrayaan-1 (2008): India’s first mission to the Moon. Launching an interplanetary probe was a complex task. The PSLV, in its XL configuration, was used to launch the Chandrayaan-1 spacecraft. It didn’t fly directly to the Moon; the PSLV placed it into a highly elliptical Earth orbit. From there, the spacecraft used its own small engine to incrementally raise its orbit over several weeks before being “slingshotted” toward the Moon. The mission was a success, and its Moon Impact Probe detected the presence of water molecules, a landmark discovery.
2. Mars Orbiter Mission (Mangalyaan) (2013): This was an even more ambitious undertaking. Using the same PSLV-XL rocket, ISRO launched an orbiter to Mars. The mission was a technology demonstrator, designed to prove India could send a probe to another planet. It used the same extended-orbit technique as Chandrayaan-1, followed by a nine-month cruise to Mars. In September 2014, the orbiter successfully entered Mars orbit, making India the first nation in the world to do so on its first attempt.

The PSLV also launched Astrosat (2015), India’s first space-based observatory, and set a world record in 2017 by launching 104 satellites on a single rocket.

The Legacy of PSLV

The PSLV’s impact cannot be overstated. It gave India autonomy in space, enabling the creation of its own large constellation of Earth observation satellites. It provided a platform for groundbreaking scientific exploration. And it opened the doors to the global commercial launch market, first through ISRO’s commercial arm Antrix Corporation and later through NewSpace India Limited (NSIL). The PSLV established ISRO as a serious, reliable, and innovative player in the global space community.

Reaching for Higher Orbits: The Geosynchronous Launch Vehicle (GSLV)

While the PSLV was a master of Low Earth Orbits and polar orbits, it had limitations. It wasn’t powerful enough to launch India’s heavy communication satellites. These satellites, part of the INSAT and GSAT series, needed to be placed in a Geosynchronous Transfer Orbit (GTO). This is a high, elliptical orbit that is a stepping stone to a final geosynchronous orbit, where a satellite orbits at the same speed as the Earth’s rotation and appears to hover over a single spot.

For decades, India was forced to pay foreign providers, primarily Europe’s Arianespace, hundreds of millions of dollars to launch these heavy satellites. This was not only expensive but also a strategic vulnerability. India needed a more powerful rocket: the Geosynchronous Satellite Launch Vehicle (GSLV).

The GSLV Mk I & Mk II: The Cryogenic Challenge

The GSLV’s design was based on the PSLV’s proven components. The GSLV Mk I used the same solid-fuel first stage as the PSLV (though with a different strap-on configuration) and a derivative of the liquid-fueled Vikas engine second stage.

The difference was the third stage. To hurl a multi-tonne satellite to GTO, a conventional solid or liquid engine wasn’t efficient enough. It required a high-energy cryogenic rocket engine. A cryogenic engine uses propellants that are liquid only at extremely cold temperatures: liquid hydrogen (LH2) as fuel and liquid oxygen (LOX) as the oxidizer. This combination provides far more “bang for the buck” (a higher specific impulse) than any other chemical propellant.

Cryogenic technology is immensely complex. Handling propellants at temperatures near absolute zero, managing high-pressure turbopumps spinning at tens of thousands of RPM, and ensuring a stable, controlled combustion is one of the most difficult feats in rocketry.

In the early 1990s, India signed a deal with Russia to purchase cryogenic engines and, just as importantly, the technology to build them. This deal was met with fierce opposition from the United States, which cited concerns about the Missile Technology Control Regime (MTCR). Under pressure, Russia backed out of the technology-transfer part of the deal, agreeing only to sell a handful of ready-made engines.

This set India’s GSLV program back by a decade, but it also hardened its resolve. ISRO was forced to develop its own cryogenic engine from scratch. This effort became the Cryogenic Upper Stage (CUS).

While its own engine was in development, ISRO began launches of the GSLV Mk I, using the purchased Russian engines. The rocket’s record was patchy. Its first flight in 2001 was a failure. The following years saw a mix of successes and failures, plaguing the rocket with reliability questions.

The real breakthrough came on January 5, 2014. After a previous attempt in 2010 failed, the GSLV-D5 mission lifted off. This was the first flight of the GSLV Mk II, defined by its use of India’s own indigenous cryogenic upper stage. The launch was a perfect success. India had finally mastered the complex technology it had been denied two decades earlier.

Since then, the GSLV Mk II has become a reliable launcher, taking over the role of launching India’s 2-tonne class communication, weather, and navigation satellites, ending the reliance on foreign launchers for this category of payload.

The Heavy Lifter: Launch Vehicle Mark 3 (LVM3)

Even as the GSLV Mk II was becoming operational, ISRO was working on an even bigger rocket. The GSLV program had taught them about cryogenic engines, but the GSLV’s core design (based on the PSLV) was a limitation. To launch the next generation of 4-tonne class satellites – and, eventually, astronauts – India needed a brand-new, clean-sheet design.

This vehicle was initially called the GSLV Mk III, but this name was misleading. It shares no components with the GSLV Mk I or Mk II. It’s an entirely different and vastly more powerful rocket. In 2022, ISRO officially renamed it the Launch Vehicle Mark 3 (LVM3) to clear up the confusion.

The LVM3 is India’s most powerful rocket. Its architecture is completely different from its predecessors:

• Strap-on Boosters: The rocket’s power comes from two massive S200 solid-fuel strap-on boosters. These are among the largest solid boosters in the world. Unusually, these boosters ignite first and provide the main thrust for liftoff.
• Core Stage: A few minutes into the flight, while the boosters are still firing, the L110 liquid-fueled core stage ignites. This stage is powered by two Vikas engines.
• Upper Stage: After the boosters and core stage have separated, the C25 cryogenic upper stage takes over. This is an all-new, high-performance indigenous cryogenic stage, far more powerful than the one used on the GSLV Mk II.

This rocket is designed to lift over 4,000 kg to GTO or up to 8,000 kg to Low Earth Orbit.

A Record of Success

The LVM3’s development was methodical. Its first flight, a suborbital test in 2014, successfully tested the atmospheric phase of flight and a prototype of the Gaganyaan crew capsule, which re-entered the atmosphere and splashed down safely.

Its first orbital flight in 2017 was a complete success, launching the GSAT-19 satellite. Since then, the LVM3 has built a perfect launch record.

Its missions have demonstrated its power and reliability:

• Chandrayaan-2 (2019): The LVM3’s first operational mission. It successfully launched India’s complex second lunar mission, which included an orbiter, lander, and rover.
• Commercial Heavy-Lift: In 2022 and 2023, the LVM3 was used for two commercial launches, placing 72 satellites for the OneWeb broadband constellation into orbit. This signaled India’s entry into the lucrative global heavy-lift launch market.
• Chandrayaan-3 (2023): On July 14, 2023, the LVM3 flawlessly launched the Chandrayaan-3 mission. Its perfect injection into orbit was the first step of the historic mission that culminated in India becoming the fourth nation to soft-land on the Moon and the first to do so near the lunar south pole.

The LVM3 is the cornerstone of India’s space ambitions. It is the vehicle that ensures complete self-reliance for all satellite launches. Most importantly, it has been selected as the rocket for the Gaganyaan program, and it is currently undergoing the human-rating process to ensure it is safe to carry Indian astronauts into orbit.

The New Generation: Agility and Reusability

The global launch market is changing. The rise of small satellites (smallsats) and the cost-reduction revolution started by companies like SpaceX have created new demands. ISRO is responding with a new generation of vehicles focused on agility and, in the long term, reusability.

SSLV: The Small Satellite Express

While the PSLV is reliable, it’s often too large and expensive for a customer who just wants to launch a single small satellite. Booking a rideshare on a PSLV can mean long waits. To fill this gap, ISRO developed the Small Satellite Launch Vehicle (SSLV).

The SSLV is designed for the “launch-on-demand” market, capable of placing up to 500 kg in LEO. Its design philosophy is all about speed and simplicity. It’s a compact, three-stage, all-solid-propellant rocket. Its key feature is its ability to be assembled and launched in a matter of days, rather than the weeks or months required for a PSLV or LVM3.

The SSLV’s development had a rocky start. Its first launch (SSLV-D1) in August 2022 failed to place its satellites into a stable orbit due to a vibration-related sensor issue. However, ISRO quickly identified and fixed the problem. Its second flight (SSLV-D2) in February 2023 was a complete success, validating the rocket’s design.

The plan for the SSLV is to transfer its production and operation entirely to the private sector, allowing NewSpace India Limited (NSIL) to market it as a dedicated, quick-response launcher for the booming global smallsat industry.

The Quest for Reusability: RLV-TD

The next great leap in rocketry is reusability. Lowering the cost of access to space requires rockets that aren’t thrown away after every flight. ISRO’s approach to this is the Reusable Launch Vehicle – Technology Demonstrator (RLV-TD).

Unlike the vertical-landing Falcon 9 rocket, ISRO’s RLV-TD is a winged body, much like a small, unmanned Space Shuttle. The concept is for a Two-Stage-to-Orbit (TSTO) vehicle, where a reusable winged booster flies to a high altitude, releases an expendable upper stage, and then flies back to land on a runway.

ISRO has been methodically testing the technologies for this.

• In 2016, the Hypersonic Flight Experiment (HEX) launched the RLV-TD on a rocket. It reached hypersonic speed, re-entered the atmosphere, and successfully splashed down in the ocean.
• In 2023 and 2024, ISRO conducted a series of Landing Experiments (LEX). In these tests, an Indian Air Force helicopter lifted the RLV prototype to an altitude of 4.5 kilometers and released it. The vehicle then had to autonomously navigate, find the runway, and perform a perfect, high-speed landing, all on its own. Both tests were flawless successes.

This is a long-term development. A fully operational reusable launch vehicle is likely more than a decade away, but these tests are building the foundational technologies that will define India’s launch capabilities in the 2030s and 2040s.

The Future: More Power and a Private Ecosystem

India’s launch vehicle program is now advancing on two parallel tracks: developing more powerful and efficient rockets within ISRO and actively fostering a domestic private space industry.

The Semi-Cryogenic Leap

The LVM3 is powerful, but ISRO is already working on its replacement engine. The SCE-200 is a 2,000-kilonewton semi-cryogenic engine. Instead of liquid hydrogen, it uses a highly refined kerosene (called RP-1) as fuel, with Liquid Oxygen (LOX) as the oxidizer.

This “sem-cryo” engine offers the best of both worlds. Kerosene is much denser than liquid hydrogen, so the fuel tanks can be smaller. It’s also not as deeply cold, making it easier to handle. At the same time, it’s far more efficient than the solid or conventional liquid propellants used in the Vikas engine.

This new engine is intended to replace the L110 liquid core stage on the LVM3. A future LVM3 variant powered by this engine would see its GTO payload capacity increase from 4 tonnes to around 6 tonnes, making it even more competitive globally. This technology is also the key to a future family of heavy-lift rockets.

The Rise of Private Rockets

The most significant change in India’s space program is the government’s decision to open the sector to private companies. The creation of the Indian National Space Promotion and Authorization Center (IN-SPACe) as a single-window agency is designed to facilitate and regulate this new private industry.

Several startups have already emerged as serious players:

• Skyroot Aerospace: In November 2022, this company made history by launching the Vikram-S, India’s first-ever privately developed and launched rocket. While a suborbital flight, it proved the model. The company is now developing its Vikram series of orbital rockets.
• Agnikul Cosmos: This startup is developing the Agnibaan rocket, which is built for small satellite launches. Its key innovation is the Agnilet engine, a semi-cryogenic engine that is entirely 3D-printed in a single piece. This drastically reduces manufacturing time and cost.

This new policy allows ISRO to focus on what it does best: pioneering R&D, deep-space science, and human spaceflight. Routine launch services, like putting satellites into LEO, can be handled by this new, competitive private industry.

Summary

India’s launch vehicle history is a testament to strategic patience and long-term vision. The program evolved from the simple SLV-3, which first gave India a place in orbit, to the ASLV, whose failures taught invaluable lessons. This was followed by the PSLV, the rocket that became the nation’s reliable workhorse, opening the door to the Moon, Mars, and the global commercial market.

The difficult, decades-long mastery of cryogenic technology enabled the GSLV Mk II, securing self-reliance for vital communication satellites. Today, the LVM3 stands as India’s heavy-lifter, a vehicle capable of launching the historic Chandrayaan-3 mission and soon, its own astronauts.

As the program moves forward, its future is defined by a dual thrust. On one hand, ISRO is pushing the boundaries of technology with semi-cryogenic engines and reusable vehicle demonstrators. On the other, a vibrant private industry is taking root, ready to build on ISRO’s legacy and create a new, commercially driven ecosystem. From a small launch pad in Thumba, India’s launch vehicle program has grown to become a versatile, capable, and formidable force in the global space economy.