Over five decades of operations, the Indian Space Research Organization (ISRO) developed several rockets capable of orbiting satellites into Low Earth Orbit (LEO), Geostationary Orbit (GEO) and beyond. This is a brief look into the history of those launch systems developed by the premier Indian space agency.
In this compilation I’m only going to mention orbital-rated launch vehicles, as such any sub-orbital launchers/sounding rockets will not be mentioned. I’m going to divide this into two parts. The first part will cover the history up till this point, the second part will talk about where things are going. So let’s start with Part-1:
Satellite Launch Vehicle (SLV)
After launching its first RH-series sounding rocket in 1967, ISRO (then known as INCOSPAR until 1969) set out to develop its first orbital rocket, and achieved this goal in 1979. The SLV, otherwise known by its unit designation SLV-3, was a four-stage rocket with all-solid propulsion, and was the first orbital flight-rated Indian rocket. The SLV only had 4 launches and could never develop into a successful launch system, but it had far-reaching implications for both the civilian space sector as well as the development of the Integrated Guided Missile Development Program (IGMDP) in the 80s and 90s that gave rise to Prithvi & Agni ballistic missiles.
Status: Decommissioned in 1983
Liftoff mass: 17 tons | Height: 22m | Payload to LEO: 40kg
Total launches: 4 | Success/Failure: 2/2 (50%)
Notable missions & their significance
RS-1 (18 July 1980): Rohini series of experimental spin-stabilized sats, first instance of an Indian satellite successfully being orbited by an Indian rocket | RS-D2 (17 April 1983): First Indian-launched satellite with onboard camera, took over 2500 pictures in both visible & infrared spectrums
Augmented Satellite Launch Vehicle (ASLV)
The ASLV was an improvement of the SLV-3 core stage accompanied by 2 additional strap-on solid boosters acting as a first-stage (taking total stages to 5), improving the payload capacity and serving as a platform for flight testing new technologies. Like the SLV that preceded it, the ASLV did not achieve commercial success but laid the technological foundation for the PSLV.
Status: Decommissioned in 1994
Liftoff Mass: 41 tons | Height: 24m | Payload to LEO: 150kg
Total launches: 4 | Success/Failure: 1/3 (25%)
Notable missions & their significance
SROSS-C2 (5 May 1994): Conducted several Gamma Ray Burst (GRB) experiments, first Indian satellite with a pure space science payload.
Polar Satellite Launch Vehicle (PSLV)
Following liberalization of the economy in 1991, India started its growth story and by 1993, thanks to the capital infusions and the technical know-how gained over the last 15 years, ISRO was ready to pursue a large-scale program for developing a medium-class launch vehicle for the dual use of supporting India’s expanding space ambitions and tapping a commercial launch market that was at the time largely dominated by the US, Western Europe & Russia.
The four-stage PSLV powered by a combination of the Vikas liquid engine and various solid boosters including S139 and PSOM SRBs was the first Indian orbital rocket that was a massive technical & commercial success, and remains continuously supported to this day by improvements in technologies, variants and continuing cost-reduction & creating a vast network of private industry to build & supply components. The PSLV allowed ISRO to pursue missions to the Moon & Mars and today, the majority of components of the PSLV are manufactured by Private companies with ISRO acting as lead integrator.
As of 2021, the PSLV & its variants including PSLV-G (original), PSLV-CA (Core Alone for lighter payloads at reduced cost) & PSLV-XL (largest capacity variant with additional strap-on boosters) launched a total of 71 Indian & 342 foreign satellites from 33 countries thanks to a mature rideshare program, putting India & ISRO on the international map as a major launch services provider with the PSLV acting as the pivotal piece of the puzzle in this turnaround, and with over 25 years of continuous operational experience & an overall success rate in the 96 percentile over 53 launches, the PSLV remains one of the most reliable & tried-and-tested launch systems currently operational in the world.
Liftoff Mass: 295 tons | Height: 44m | Payload to LEO: 3800kg | Payload to GTO: 1300kg | All vehicle stats are of original PSLV, the XL variant is heavier & capable of greater payloads
Total launches: 53 | Success/Failure: 51/2 (96.3%)
Notable missions & their significance – too many to list but some of the most important are:
IRS-P2 (15 October 1994): First Indian remote-sensing satellite launched on domestic rocket, went on to form the IRS constellation, one of the biggest exclusively remote-sensing constellations in the world | CARTOSAT-1 (5 May 2005): First dual-use geocentric Earth-observation satellite of 2.5m resolution, with both civilian & strategic uses | SRE-1 (10 January 2007): Space capsule Recovery Experiment, tested the first atmospheric re-entry capable capsule with first-generation heat shield & silica tiles | Chandrayaan-1 (22 October 2008): First Indian mission to the Moon, carried an orbiter & a Moon Impact Probe (MIP) that placed the Indian Flag on the surface of Luna | RISAT-2 (20 April 2009): First Indian-built radar reconnaissance satellite with Synthetic Aperture Radar (SAR) payload | Various INSAT & GSAT series: Geostationary communication constellations | IRNSS-1A (1 July 2013): First of the IRNSS (now called NaVIC) navigation satellite constellation, Indian alternative to US GPS | MOM (5 November 2013): Mars Orbiter Mission, first ISRO interplanetary mission | Astrosat-1 (28 September 2015): First dedicated Indian Space-based observatory that made many discoveries including AUDFs01, currently one of the oldest known galaxies | PSLV-C37 (15 February 2017): With a launch of 104 satellites (majority of them American) the PSLV held the record of most sats launched on a single rocket from 2017-2021 when it was superseded by SpaceX’s Falcon 9 Transporter-1 mission with 143 sats | HySIS (29 November 2018): First Indian hyperspectral imaging satellite | Microsat-R (25 January 2019): Secretive experimental sat that served as tagret for March 2019 ASAT weapon test | EMISAT (1 April 2019): First dedicated ELINT satellite | CARTOSAT-3 (27 November 2019): First of Next-gen series of EO satellites with <0.25m resolution
Geosynchronous Satellite Launch Vehicle (GSLV)
With the success of PSLV under its belt, ISRO started on the course of attaining greater access to Geostationary orbits for the country’s expanding communication satellite needs, which meant building bigger & better rockets. A key part of this included obtaining cryogenic rocket engine technology – a closely guarded tech only available with a handful of countries. Initially, while indigenous design & development continued under the Cryogenic Upper Stage Program (CUSP), ISRO decided to obtain fully-built KVD-1 engines from Russia to power the new GSLV upper stage in vacuum.
The GSLV was a 3-stage liquid-solid rocket with Vikas liquid engines powering strap-on boosters, solid S125 motor powering the core stage, another Vikas on the 2nd stage and KVD-1 cryo-engine powering the 3rd stage.
There were many problems including threat of US sanctions on Russia if they continued to supply the engines to India, leading to the supply ceasing after only 7 engines were delivered. With the limited numbers, the development of the rocket had to be optimized to the extreme as ISRO had to sparingly use the motors as they perfected the GSLV design test launch after test launch, but with the engines poorly optimized for Indian launch & weather conditions, failures were frequent. In the end the GSLV configuration as it existed (now known as Mk-1), with the Russian cryogenic engine, was never going to become a commercially viable product.
But, it allowed ISRO to perfect the launch vehicle design itself, with the only piece of the puzzle left for it to become a success was the Indian cryogenic engine – which came with the GSLV Mk-II.
Status: Decommissioned in 2010
Liftoff mass: 415 tons | Height: 49m | Payload to LEO: 5000kg | Payload to GTO: 2700kg
Total launches: 6 | Success/Failure: 2/4 (33%)
Geosynchronous Satellite Launch Vehicle (GSLV) Mk-II
The GSLV Mk-2 is essentially the same as the Mk-1, with the only difference being that the Russian KVD-1 cryogenic engine being replaced with the indigenously designed & built CE-7.5 Cryogenic Upper Stage (CUS) staged-combustion cycle motor, developed under CUSP. With the CE-7.5 in place, India was now free to develop its geostationary orbit-class rockets as it wished, and despite a failure in the initial test flight, ISRO eventually managed to make the GSLV Mk-2 into a successful platform.
Over the course of its flights, the Mk-2 also served as a platform to validate several new propulsion technologies including the High Thrust Vikas Engine (HTVE) and the uprated C12.5 and C15 cryogenic engines.
Ironically, despite the large US hand in curtailing the early development of this class of rocket, the GSLV Mk-2 is the intended launch vehicle for the NISAR, a US-India joint project to develop the world’s first Dual-band SweepSAR satellite, with a launch expected in 2022-23. With a shared development cost of $1.5 billion the NISAR is likely the most expensive Earth-imaging satellite ever built.
Liftoff mass: 415 tons | Height: 49m | Payload to LEO: 5000-6500kg | Payload to GTO: 2700-3200kg
Total launches: 7 | Success/Failure: 6/1 (85%)
Notable missions & their significance
INSAT-4E/GSAT-6 (27 August 2015): First Indian-launched satellite exceeding launch mass of 2 tons | South Asia Satellite (5 May 2017): Geostationary communication & meteorological satellite providing free services to SAARC nations as a gift from India | GSAT-7A (19 December 2018): First dedicated military communication satellite for the Indian Air Force
Geosynchronous Satellite Launch Vehicle (GSLV) Mk-III
While the GSLV Mk-2 did improve the payload capacity of ISRO launch vehicles over the earlier PSLV and could serve as a commercial launch platform going forward, it however wouldn’t be enough to support India’s growing ambitions of potentially building a human spaceflight-capable launch system. This gave rise to the development of the Mk-3 GSLV platform (even though called Mk-3 it had little in common with the Mk-1/2 and for this reason was also known as LVM3) supported by next-gen developments in both liquid & solid propulsion systems such as the CE-20 Cryogenic stage and the S200 solid rocket booster respectively (believed to be 3rd largest SRB in the world after the Space Shuttle’s and the Ariane-5’s solid boosters). The Mk-3 was also the first Indian rocket to use a clustered liquid stage with 2 x Vikas engines forming the core of the first stage.
In 2014, the Mk-3 was tested for the first time for a sub-orbital launch, and a full orbital launch in 2017 with a functioning Cryogenic stage. In all of its 4 launches so far (including Chandrayaan-2 mission) the vehicle continued to introduce new refinements to its design such as a new nose fairing, improvements to the HTVE engines among others, which allowed for a LEO payload capacity exceeding 10 tons.
A human-rated variant of the Mk-3 is the intended launch platform for India’s upcoming manned spaceflight program Gaganyaan. With a 100% success rate in the launches even in the initial testing period with many unproven technologies, the Mk-3 is inspiring confidence as a human transportation system, as well as emerging as a reliable platform for potential large-scale commercial launches.
Liftoff mass: 640 tons | Height: 43m | Payload to LEO: 10,000kg | Payload to GTO: 4000kg
Total launches: 4 | Success/Failure: 4/0 (100%)
Notable missions & their significance
CARE (18 December 2014): Crew module Atmospheric Re-entry Experiment, demonstrated the successful re-entry & recovery of a test version of the Gaganyaan crew module | GSAT-19 (5 June 2017): First Indian-launched satellite exceeding mass of 3 tons, also first to use indigenous Li-ion batteries | GSAT-29 (14 November 2018): First Indian High-Throughput communication Satellite (HTS) | Chandrayaan-2 (22 July 2019): Second Indian moon mission, this time with orbiter + lander + rover for a combined mass exceeding 3.8 tons into LTO
Reusable Launch Vehicle-Technology Demonstrator (RLV-TD)
While the Indian space program proceeds forward with proven technologies, ISRO remains at work with various R&D programs for developing next-gen launch solutions such as re-usable spaceplane systems powered by Scramjets (among others which we will talk about in Part-2) for both civilian & strategic needs.
As part of these R&D projects, ISRO test flew a scaled-down shuttle-type spaceplane called the RLV-TD in 2016. Roughly the same size as the Boeing X-40 Space Maneuver Vehicle which served as precursor to the secretive X-37B space plane, the RLV-TD as its name suggests is intended to serve as a platform for validating various new technologies such as hypersonic flight, re-entry and autonomous runway landing under own power.
The 2016 test, known as HEX (Hypersonic flight EXperiment) was geared toward validating the aerodynamic qualities of the fuselage as well as testing the re-entry heat tolerances of the silica tiles on the bottom of the plane as the TD made a controlled splashdown in the ocean. Although this was a sub-orbital test, its intended to develop an orbital system and the re-entry at approx Mach 5 gave tremendous amounts of data for further refining the design as a new test called LEX or Landing Experiment which will incorporate release of the plane from a helicopter and touching down with its own landing gear is scheduled for sometime this year, this will be followed by 2 more tests namely REX (Return flight) and SPEX (Scramjet Propulsion) which will fully validate the design and result in a finished product that will be much larger (estimated to be considerably bigger than even the X-37B, and approaching the Space Shuttle in size) and capable of orbiting multiple satellites (or carry astronauts) in each mission.
The completed RLV will most likely be launched on top of a GSLV Mk3-sized first stage booster.
Status: Under development
Liftoff mass: 1.75 tons or 12 tons including booster | Height: 16m with Orbiter length of 6.5m
Total launches: 1 (success)
In Part-2 I’ll go over some of the ongoing projects (which haven’t been flown yet) that will shape the future of India’s launch capabilities.
I’ll be closing off Part-1 with this amazing photograph (and no, its not a photoshop) of the GSLV Mk-3 as it launches the Chandrayaan-2 combined orbiter-lander-rover payload into Lunar Transfer Orbit. The payloads successfully reached their destination, however the lander made a hard touchdown, crashing into the lunar surface. The orbiter, however, remains in operation, the second Indian satellite to orbit Luna after 2008’s Chandrayaan-1.