India in Space, Part 1: From Slow Start to Leading Space Power

On August 23, 2023, the world’s spacefaring nations welcomed a new member: India’s unmanned landing platform, Chandrayaan 3, which launched from the Satish Dhawan Space Center (SDSC) on an Indian-made LVM-3 rocket five weeks earlier, had touched down at the Moon’s south pole. This event made India the fourth country in the world to independently organize and accomplish one of the most complex technological tasks in history. 

Today, we will explore how a country that did not have a single satellite in orbit just 50 years ago managed to achieve such results. This is the triumphant story of the Indian space program.

Early ventures: the Aryabhata satellite and the Rohini constellation 

The history of the Indian Space Research Organisation (ISRO) began in 1962 when then-Prime Minister Jawaharlal Nehru recognized the scientific and economic potential of space research. By his directive, the Indian National Committee for Space Research (INCOSPAR) was established. INCOSPAR was renamed to the ISRO in 1969.

The first serious goal of the newly formed space agency was to launch its own satellite. In the early 1970s, however, India had no experience with this. Its first small launch vehicle, Rohini RH-75, despite successfully conducting 15 consecutive launches between 1967 and 1968, could only reach a maximum altitude of 50 km, which was insufficient to place a satellite even into low Earth orbit (LEO). Meanwhile, its Satellite Launch Vehicle (SLV), which was expressly intended to place satellites into orbit, had not yet been completed.

Given these circumstances, India had to seek help from one of two other spacefaring nations to launch its satellite. In the end, it chose the Soviet Union and in 1972 the two countries signed an agreement for cooperation in aerospace activities. In exchange for access to Soviet rockets, India agreed to open certain ports and docking facilities to the Soviet navy. Not long after signing the agreement, the ISRO began work on its first satellite, Aryabhata, which was named after an Indian astronomer who lived in the 5th century CE.

The main goal of the Aryabhata mission was to conduct experiments in X-ray astronomy and solar physics. The spacecraft, with a diameter of 1.4 meters, was completely covered with solar panels to ensure a continuous supply of electricity for powering the satellite.

On April 19, 1975, Aryabhata embarked on its journey into space from the Soviet launch site near Kapustin Yar on a “Kosmos-3M” launch vehicle. The satellite successfully detached from the rocket in low Earth orbit at an altitude of approximately 600 km. However, it was too optimistic to hope that the ISRO’s first mission would turn out to be a complete success. Despite its numerous solar panels, Aryabhata experienced a critical failure in its power system on its fourth day of operation. The probe’s battery lasted for one more day, after which the satellite stopped transmitting signals back to Earth. Its orbit, however, continued until February 1992, when it finally burned up in the Earth’s atmosphere.

Despite this failure, Aryabhata kickstarted India’s independent satellite industry. Just five years later, ISRO began launching its own satellite constellation, which was to consist of four Rohini Satellite (RS) probes. 

The first experimental satellite, named Rohini Technology Payload (RTP), was launched on August 10, 1979, from India’s main launch site, the Satish Dhawan Space Centre, which was established in 1969. Despite a successful launch, however, the RTP never reached orbit due to a fuel valve malfunction and it ultimately crashed into the waters of the Bay of Bengal.

That same year, the USSR also helped India launch the first of its pair of Earth observation satellites, Bhaskara I (1979), which was later followed by Bhaskara II (1981). Their two wide-angle cameras were used to study the oceans, monitor forests, and investigate geological structures. The mission lasted 10 years, after which ISRO ceased operations of the satellites. Bhaskara I re-entered Earth’s atmosphere in 1989, with Bhaskara II following in 1991.

Despite the failure of SLV-3 E1, India achieved its first orbital launch with the next version of the SLV-3. This historic event occurred on July 18, 1980, when the launch vehicle successfully delivered the RS-1 satellite, making India the seventh country in the world with the technical capability to put satellites into orbit.

Once in orbit, RS-1 activated its sensors, which included a magnetometer, a temperature sensor, and a unique digital sensor for observing the Sun. The spacecraft conducted research until May 20, 1981, after which it deorbited and burned up in the atmosphere.

Over the next three years, SLV-3 was launched two more times, with its last launch occurring in 1983. The rocket was subsequently retired. India had finally shed its dependence on other spacefaring nations, taking full control over the development of its space program.

Development of India’s rocket fleet: the emergence of the PSLV

Along with the development of the SLV-3, India also hoped to build rockets that had more power and payload capacity. In 1982, the ISRO began preliminary work on the Polar Satellite Launch Vehicle (PSLV), a four-stage medium-lift rocket designed to deliver satellites into high polar and sun-synchronous (SSO: 550 km) orbits.

However, the development of the PSLV was not as swift as its predecessor, primarily because it had a complex four-stage architecture that left little room for error during launches. As a result, it took 15 long years before India’s first medium-lift rocket was ready.

The PSLV project started in 1978 when ISRO received 35 different proposals for the future rocket. By 1980, only four of these projects remained viable, and the final selection took place two years later. The biggest issue lay in how to power the rocket’s final stage: at that time, most proposals focused on solid fuels, which were ineffective in near-space, while liquid-fuelled engines were considered superior.

To develop new types of cryogenic engines, the ISRO established the Liquid Propulsion Systems Center (LPSC), a research facility for producing liquid and cryogenic rocket engines, in Thiruvananthapuram in 1985. The establishment of the LPSC played a crucial role not only in the development of the PSLV but also in many other, more powerful, rocket systems, including the GSLV (for launching into geosynchronous orbit), the ASLV (to expand satellite launch capabilities), and others.

The development of liquid propellants, which was proposed by LPSC, made the PSLV rocket into something like a layer cake. The first stage (PS1) is the main booster, which is powered by the solid-fuel propulsion system S139, whose thrust is supplemented by six strap-on boosters (in the Core Alone (CA) version, the strap-on boosters are not used).

The second stage of the rocket (PS2), meanwhile, uses the liquid-fuelled Vikas engine, also developed by LPSC, which is capable of producing 799 kN of thrust. The third stage (PS3), was designed to operate for only 113 seconds and again uses solid fuel. Its propulsion system, with a thrust of 250 kN, operates on a solid fuel mixture of polybutadiene with terminal hydroxyl groups (HTPB). The final stage of the rocket’s flight is powered by paired cryogenic engines with regenerative cooling, each producing 7.3 kN of thrust, along with a smooth steering system provided by six 50N RCS mini-engines.

On September 20, 1993, India launched the first modification of the sun-polar PSLV-G. It was a relatively unsuccessful launch, as only the first two stages of the rocket functioned normally. During the separation of the third and fourth stages, an anomaly occurred that resulted in the loss of the mission’s payload. Nevertheless, India was one step away from becoming the second commercial provider in the world of launch services for these types of missions. Before India entered this market in 1993, only Russia had the capability to launch commercial satellites into these orbit.

In October of the following year, 1994, the PSLV-G completed its first fully successful launch. This highly successful modification served for another 22 years, finally being retired in September 2016 after the PSLV-C35 mission. This version of the rocket was capable of launching payloads of up to 1,678 kg into sun-synchronous orbits (SSO: 600+ km). As of today, ISRO operates seven other PSLV modifications, each designed for specific mission needs:

• PSLV-C. First launch: April 23, 2007. A model without six strap-on boosters. PS-1 only relies on the thrust from the main propulsion system (S139) for launches. This modification consumes less fuel and carries 400 kg less fuel for the fourth stage. However, it is also less powerful, only being able to deliver spacecraft weighing up to 1,100 kg to SSO.
• PSLV-XL. First launch: October 22, 2008. A more powerful variant of the standard PSLV-G, featuring extended strap-on boosters. This allows for an increased payload capacity of up to 1,750 kg to SSO. This modification made its debut with the launch of the Chandrayaan 1 lunar lander, demonstrating that the extended design of the auxiliary boosters has advantages for launching extraterrestrial missions.
• PSLV-DL. First launch: January 24, 2019. A version of the rocket with two strap-on boosters located on the main booster, along with a 12-ton fuel tank.
• PSLV-QL. First launch: April 1, 2019. A rocket version equipped with four strap-on boosters on the first stage. This is a kind of middle ground for PSLV’s rocket capabilities, able to deliver 1,523 kg to SSO.

Despite more than 30 years of operational history, ISRO is in no hurry to retire the PSLV. After 50 consecutive successful launches, global trust in the agency’s rockets has only continued to grow.

A newly announced rocket modification called PSLV-3S is also currently under development. This rocket’s capabilities will be sufficient even for launching small payloads into remote geosynchronous and geostationary orbits (GEO: 35,578+ km). However, to launch more serious space missions to GEO and beyond, ISRO required a more capable transport system. The most powerful rocket currently in ISRO’s arsenal, the GSLV, was developed to serve this niche.

GSLV: a path best traveled alone

The architecture of the Geosynchronous Satellite Launch Vehicle (GSLV) includes three stages, combined based on the principle of sequential employment of different types of propulsion engines. The main solid booster (CA) was entirely borrowed from the PSLV, but the four side boosters on its fuselage used the liquid Vikas engine, for which additional space was allocated on the first stage. The second stage of the rocket was also almost entirely copied from PSLV but utilized more powerful Vikas engines. So what allows the GSLV to deliver a payload of up to 2.5 tons to geosynchronous orbit?

The main distinction was intended to be the third stage of the rocket, which would be powered by a liquid engine, albeit one with significantly greater thrust than that of the PSLV’s final stage engine. ISRO indeed had a very modern vision for its new rocket, fully in line with the technological trends of that time, including a desire to reduce the number of stages and use more powerful cryogenic engines capable of steering during the final phases of the rocket’s flight.

Unfortunately, the ISRO decided not to produce the new engine at the LPSC, instead opting to acquire a ready-made solution from the market. The most accessible and cheapest option, the cryogenic KVD-1M engine, was available from Russia and was adopted for the third stage of GSLV Mark I. Although the KVD-1M had previously been used successfully by Roscosmos, attempts to adapt it for the GSLV project effectively doomed the first version of the Mark I.

After the GSLV Mk.I’s unsuccessful launch in 2001, it became clear that the KVD-1M, which had been developed specifically for Russia’s Proton heavy rockets, was simply not compatible with the GSLV, a medium-class rocket. As a result, only two of six attempts to launch the GLSV into geosynchronous orbit were successful. In the end, every failure or partial failure was caused by thrust discrepancies, resulting in spacecraft being placed in improper orbits. Most of these missions, furthermore, were commercial, meaning that customers lost valuable equipment, causing them to become reluctant to conclude further contracts with India. The ISRO realized that the engine for the last stage of the rocket would have to be developed in-house.

As it happened, India had a window of opportunity to develop its own cryogenic engines under license in the 1990s. At that time, ISRO and Roscosmos had signed an agreement on the exchange of rocket technologies, meaning that there was a possibility for the transfer of KVD-1M prototypes and other Russian technologies, which could have stimulated the domestic development of rocket components in India. However, all of this was put to a stop by the United States, which imposed sanctions on both agencies, essentially setting India’s rocket development program back by years. 

In any case, India’s “solitary path” was not a quick one: the working version of the new CE7.5 cryogenic remained under development for a long 20 years and its first successful demonstration occurred only in 2014. Operating on a fuel mixture of liquid oxygen and liquid hydrogen (LOX/LH2), it was capable of providing between 73.5-75 kN of pure thrust in standard mode and 91.5 kN in boost mode. In the end, the Indian engine turned out to be even more powerful than the KVD-1M. Since January 2014, when the first cryogenic upper stage (CUS) was successfully tested on the GSLV Mk.II, this modification of the rocket has achieved six consecutive successes, effectively saving GSLV from failure.

The CE7.5 was immediately approved for use on the third modification of the GSLV Mark III, also known as LVM-3. Even externally, the engine represented a completely different perspective on the capabilities offered by new types of cryogenic engines: namely that they could deliver significantly larger payloads into orbit. Currently, there are three main modifications of the GSLV: Mark I (equipped with the KVD-1M engine on the final stage), Mark II (equipped with a CE7.5 produced by LPSC), and Mark III (also known as LVM-3).

The LVM-3 became the most powerful operational rocket in the ISRO’s arsenal and, in the end, shared little with its predecessor, Mark II. Its core stage, L110, is powered by two liquid Vikas engines developed at LPSC. Second stage thrust is enhanced by the capabilities of two solid-fuel boosters, S200, which are used during the launch phase and operate on a propellant mixture of polybutadiene with hydroxyl-terminated groups (HTPB). The third, cryogenic, stage of the rocket is equipped with the CE20 liquid engine, which is a more powerful version of the CE7.5 installed on the previous generation of the GSLV.

Although the LVM-3 is technically a medium-class rocket, its reimagined design allows the vehicle to deliver up to 4 tons of payload into GEO and up to 8 tons to LEO. The rocket is also impressively reliable, with a 100% success rate (all seven of its launches have gone according to plan). Among LVM-3’s clients are the British company OneWeb, which put 72 satellites into orbit during two LVM-3 missions, as well as several state satellite operators, including Indian GSAT satellites, and, of course, the Chandrayaan 3 lunar craft, which in 2023 achieved India’s first successful soft landing on the Moon.

The history of the first launch vehicle that India hoped to use specifically for commercial deliveries to geosynchronous orbit contains a valuable lesson: it highlighted to ISRO the crucial need to develop its own cryogenic engine fleet. Without this, it would simply have been impossible to hope for dominance in interplanetary missions and to actively grow its fleet of satellites.

Ultimately, its production of locally designed cryogenic engines became a key factor in strengthening India’s position among other spacefaring nations. The new engines enabled Delhi to deliver telecommunications, navigation, and observation satellites to previously unreachable orbital altitudes. Moreover, it was able to do this on its own, without the need for third-party launch vehicles. India has not squandered this opportunity, either: in the decade of “independence” granted by these new rockets, it has invested heavily in the development of the country’s first crewed space program.

India’s LPSC, moreover, has become a major center for the design and production of various types of liquid rocket engines used on the fourth stage of the PSLV, a range of different satellites, as well as on a number of spacecraft and landing modules in recent years. Such engines transported Chandrayaan 3 to the Moon’s south pole and will soon demonstrate their capabilities in the first crewed demonstration of India’s Gaganyaan spacecraft. You can read about these and many other space missions in our next article dedicated to India’s space program over the past decade.