Rewind: And then it happened…

Odyssey of Indian space programmes may appear all of a sudden but each is according to a master plan — from the first satellite Aryabhatta to Chandrayaan-3

By Harish CS

Scientific explorations culminating in path-breaking inventions or spectacular technology demonstrations may appear all of a sudden and at times be interpreted as accidents by the common man. However, behind every such odyssey, there will be years of struggle by passionate and committed individuals, which largely remain obscure; and many a time, scarcely get documented. The Indian space programme is a classic representation of this. We are often shown only the final results and not the trials and tribulations.

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Now, as India is basking in the crowning glory of the Chandrayaan-3 success, becoming only the fourth nation to successfully demonstrate a soft touchdown on the lunar surface and the first to do so near the south pole of the moon, it is prudent to look at the incredible journey of the Indian space programme —  from the baby steps in sounding rockets, maturing to interplanetary space missions and with programmes for an eventual Indian human spaceflight in the near future.

1960s, the beginning

There was a real awakening among physicists all around the world in the late 1950s following the observance of the International Geophysical Year (IGY) (1 July 1957 to 31 Dec 1958). Scientists from the 67 participating countries, including India, resolved to undertake studies to understand more about Earth through various projects. Rockets and satellites were identified as critical tools in these experiments. Even the launch of the first artificial satellite Sputnik-1 by the USSR can be linked to IGY.

Following the euphoria, space programmes got a fillip, specifically in the US and the erstwhile USSR. In June 1960, in Geneva, the UN set up a ten-nation working group to examine the international exchange of scientific information on outer space. Another group chaired by Dr Vikram A Sarabhai was set up to examine the US proposal for establishing an international rocket range near the equator. Dr Sarabhai, being a cosmic ray scientist, knew exactly where this station ought to be. It has to be near the magnetic equator which allows the study of the atmosphere in the presence of equatorial electrojets resulting in more insights into the phenomena. He, along with Dr Homi J Bhabha, went out to establish the first sounding rocket launch station at Thumba, a sleepy fishing village off the coast of Thiruvananthapuram, Kerala.

The first launch took place on 21 November 1963 — US supplied a Nike-Apache sounding rocket with sodium vapour dispensing payload from France and the mission was supported by telemetry and tracking systems from the USSR. A truly international effort as envisioned by the UN.

Dr Sarabhai believed in a process, which he used to refer to as leap-frogging. He felt we needed to collaborate to master technologies related to rocketry at a faster rate. Soon Centaur programme was launched in collaboration with France, which enabled fast-paced developments in propellants and fabrication. Dr Sarabhai also ensured the dedication of the Thumba Equatorial Rocket Launch Station (TERLS) to the UN and invited all members to actively use it. Scientists all around the world converged on this rocket station. Thumba became synonymous with Indian rocketry and global cooperation.

Dr Vikram Sarabhai had said, “To us, there is no ambiguity of purpose……we must be second to none in the application of advanced technologies to the real problems of man and society.”  This has remained the motto of the Indian Space programme — it had the common Indian in mind always

 The programme matured under the mentorship of committed scientists handpicked by Dr Sarabhai and Dr Bhabha from around the world during their interactive journeys in the global scientific community. Local talents were also chosen along with people experienced in armaments. The baptism was by fire though; everyone realised that rocket science is unforgiving. Every failure results in a big explosion — leaving nothing to examine for investigating the cause.

It took five years for India to have its own sounding rockets. The Rohini series was inducted with a modest 75 mm diameter version and was launched from TERLS in 1968. This was followed by bigger and better versions of RSRs — the Rohini Sounding Rockets.

Practically every Wednesday, the shores of Thumba and the city of Thiruvananthapuram reverberated with the thunderous sound of a rocket launch. Even today, Rohini Sounding Rocket remains the mainstay for upper atmospheric studies in the country

 Satellite Launch Vehicles

Dr Sarabhai understood the potential of utilising satellite technology in a vast country like India with remote villages, which were not well connected to main cities. Many of them were inaccessible even by road. Advanced education, healthcare and even news of developments elsewhere in the country and world seldom reached the inhabitants.

Dr Sarabhai established an agreement with the US, through which the geostationary ATS-6 satellite was leased to India for one year from August 1975, during which the satellite was moved to 38°E longitude, primarily to facilitate the Satellite Instructional Television Experiment (SITE) of ISRO, the stepping stone for space-based television services to remote locations of India. This led to serious debates culminating in various projects of satellites and satellite launch vehicles (SLV).

Soon the first satellite of India, Aryabhatta, was launched in 1975 from the USSR, followed by the first remote sensing satellite Bhaskara I in 1979 and APPLE (Ariane Passenger Payload Experiment) — the first attempt at communication satellite in 1981. The most important fallout of these was the decision to design, develop and realise indigenous SLVs.

While Dr Sarabhai opened up vistas for development in rocketry and satellites, it was Prof Sathish Dhawan who mentored and established the famed ‘ISRO culture’ – an attitude of unmatched commitment, always rising from failures to perform miraculous successes at unexpected times. It was during this period that Prof Dhawan constituted the development project SLV-3, with APJ Abdul Kalam as its project director. By the end of 1979, Prof UR Rao was called from the Physical Research Laboratory, Ahmedabad, to head a team of engineers to design develop and realise satellites.

Simultaneously, Sriharikota, a remote island on the Andhra coast between the Pulikat Lake and the Bay of Bengal, was chosen to be the spaceport of India with the launch pad and associated facilities. The safety of the place also allowed the establishment of propellant preparation plants of large scale and test facilities for solid rockets.

SLV and ASLV, the Learning Platforms

When Aryabhatta, Bhaskara I and APPLE were scheduled to be launched, a bunch of engineers at the Space Science and Technology Centre, predecessor to the R&D wing of Vikram Sarabhai Space Centre, dared to dream of a fully indigenous launch vehicle. It was decided to tread on known paths and so the launch vehicle was to be of solid propulsion elements for all stages. The project team visited 31 industries. Different sounding rocket configurations were examined. The SLV was finalised as a four-stage launch vehicle — 23 m long weighing 17 tonnes and capable of injecting a 45 kg satellite into a 450 x 1,000 km nominal orbit.

The first flight of SLV-3 on 10 August 1979 ended in a failure but in ISRO parlance it was a partially unsuccessful mission because 33 out of 44 major subsystems performed as expected. ISRO bounced back with a success on 18 July 1980. That rewrote the destiny of all, specifically that of its project director APJ Abdul Kalam  

The SLV gave insights into many technologies but certain key elements like strap-on and vertical integration inside a service building were missing. Also, there was a need to mature to bigger payloads of 150 kg class. All these led to the conception of the Augmented Satellite Launch Vehicle (ASLV), which was basically an SLV with two of the first-stage motors of the SLV added as strap-ons. However, the initial two flights of ASLV were failures. This only strengthened the ISRO teams.

PSLV, Real Game Changer

In the late 1980s, under the leadership of Dr S Sreenivasan, ISRO engineers were in front of the drawing boards designing a much bigger launch vehicle when ASLV was failing. This unwavering commitment resulted in the workhorse launch vehicle PSLV. The Polar Satellite Launch Vehicle (PSLV) was primarily designed to inject satellites into polar orbits for Earth observation, but later under the directorship of Dr G Madhavan Nair and others, the PSLV broke away from its first intention —  did missions to geo transfer orbits and went on to accomplish astonishing missions including Chandrayaan-1 and Mangalyaan or Mars Orbiter Mission (MOM) and space capsule recovery experiment – the prelude to Indian Human spaceflight Gaganyaan.

The programme equipped Indian industries to handle big hardware. HAL established a dedicated aerospace division. L&T, Godrej, Walchandnagar Industries and many others became active partners in the Indian space programme. At the Satish Dhawan Space Centre SHAR (Sriharikota range), a launch pad with a mobile structure more than 20 storeys high was realised. The PSLV also inducted the Vikas liquid engine for the first time — an Indian version of the Viking engine of SEP, France. It now has many variants and is undoubtedly the workhorse launch vehicle of our country demonstrated by its 54 successful missions.

GSLV, and Cryo Propulsion

PSLV’s first design was for a payload of 1,000 kg. The Geosynchronous Satellite Launch Vehicle (GSLV) stems from the desire to develop a launch vehicle with a 2,000 kg payload and the capability to perform geostationary transfer orbit (GTO) missions. Initial studies revealed that apart from solid and Earth-storable liquid propulsion technology at hand, ISRO needed cryo propulsion to perform a satisfactory GTO mission. For a faster development cycle, a technology acquisition agreement was signed with the erstwhile USSR. However, geopolitical situations in the late 1990s prohibited the transfer of technology, but the integrated cryo stages were delivered for initial missions. This was a blessing in disguise.

An equivalent indigenous cryo upper stage was soon realised by the Liquid Propulsion Systems Centre of ISRO which eventually led to the realisation of a totally new design of cryo stage, which is used in the new generation LVM3 vehicles. The GSLV is a very complex vehicle with five liquid stages, one solid propellant stage and one cryo stage.

LVM3, the Current Generation

The Launch Vehicle Mark-3 or LVM3 has only three stages; two solid strap-ons, one twin-engine liquid core and a final cryo stage. It is now the chosen vehicle for Gaganyaan. LVM3 had an experimental flight in December 2014, under the leadership of S Somanath. A simulated crew module did a successful re-entry experiment on that flight. The deployment of 72 OneWeb India satellites through two missions was a notable achievement of LVM3. The best mission as yet by LVM3 is the recent Chandrayaan-3.

Satellites and Science Missions 

While progress was recorded in launch vehicles, satellites were not far behind. Exciting programmes like tele-education and tele-medicine were executed and Direct-to-Home beaming is now a reality. We have a positioning system NAVIC (regional satellite navigation system) in place. The first Chandrayaan mission proved our capability to escape from the Earth’s gravity to be captured by the Moon.

It was APJ Abdul Kalam who suggested that a probe with the Indian flag should crash land on the Moon in the first mission itself. MIP, the moon impact probe, was accordingly conceived

 The Mars Orbiter Mission (MOM) proved our ability for intricate inter-planetary travel, deep space communication and autonomous mission execution. All these became useful during the recent Chandrayaan-3 mission. These missions are providing platforms for fundamental scientific quests like the discovery of water on Mars and sulphur on the Moon.

Gaganyaan, the Ultimate Pinnacle

Undertaking an Indian human spaceflight is a dream for every Indian and more so for the space scientists of the country. Putting a man in LEO (low Earth orbit) is easy; the difficult part is to retain him there and bring him back safely to the Earth. A host of technologies have to be mastered. A Crew Escape System (CES) to separate the crew module and position it at a safe distance in case of an emergency is individually tested through an integrated airdrop test and Pad Abort Test. A full-fledged unmanned mission is also planned shortly. Astronauts are undergoing training. Very soon the first Indian human spaceflight will be a reality, all of a sudden!

Not By Chance

It is not easy to travel in the wilderness of deep space. It is equally difficult to escape from the gravity of the Earth and get captured by the gravity of another celestial body. The enterprise becomes extremely challenging as the entire domain is closely guarded and never shared. ISRO reached this level of eminence from scratch through measured steps.

With a TSTO — two-stage to orbit vehicle, ISRO has seriously embarked on mastering the required technologies of RLV (Reusable Launch Vehicle). In May 2016, a winged RLV did a hypersonic re-entry flight and in April 2023 the same module did a fully autonomous landing experiment. Works are under way for an orbital re-entry mission and for demonstration of vertical landing technology

Sounding rockets paved the way for the more complex launch vehicles. Progressive improvements were made in Earth observation through successive satellites. Technology acquisition was fast-paced through collaboration. Accrued knowledge in propulsion, mission planning, telemetry tracking, project management and a myriad of complex technologies matured at different laboratories at different centres of ISRO making things happen. It may appear all of a sudden but every programme is as expected and according to a master plan.

(The author is Former Deputy Director, Vikram Sarabhai Space Centre, ISRO)