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GSLV Gyan: Why Experts Think the Mk III Is a Big Deal for ISRO and India

It is not often that a single rocket inspires conversations across history, politics, astronomy, engineering, communications and business at once.

The GSLV Mk III at the Satish Dhawan Space Centre, Sriharikota. Credit: ISRO

The GSLV Mk III at the Satish Dhawan Space Centre, Sriharikota. Credit: ISRO

Update: ISRO successfully launched the GSLV Mk III on Monday, June 5.

At 5:28 pm on June 5, the Indian Space Research Organisation (ISRO) will attempt to launch the Mk III variant of its Geosynchronous Satellite Launch Vehicle (GSLV). It will be an historic occasion for the country’s space programme. The Mk III is ISRO’s most muscular launch vehicle to date, being able to lift 4,000 kg of payloads to the geostationary transfer orbit (GTO) and 10,000 kg to the low-Earth orbit. These capacities have been enabled by a third stage powered by an indigenous cryogenic engine, the development of which has engaged ISRO’s best for over two decades. Naturally, the success of this rocket will mean a lot for India, in a variety of ways that can be difficult to assimilate.

So The Wire asked five experts – in space policy, space science, commercial spaceflight, geopolitics and journalism – to chip in. Their comments, edited for clarity, are presented below.


Rajeshwari Rajagopalan Pillai, Senior fellow and Head, Nuclear & Space Policy Initiative, Observer Research Foundation, New Delhi

The GSLV Mk III launch slated for early June, which will showcase ISRO’s fully indigenous cryogenic upper stage, is a major achievement for India. So far, India has relied on the French Ariane 5 rocket to launch its heavy satellites and it has remained an important component of India-France space cooperation. Two decades ago, this technology was denied to India by the Soviet Union under pressure from the US. Export controls on strategic technologies were used to prevent India from developing missile or nuclear technology. Today, the equations have changed and India is on the other side of the table.

Since the early 2000s, the rationale of technology export control regimes and its dynamics have undergone some change. Despite technology controls, the West, and the US in particular, had to recognise the new reality, that they could not entirely control the spread of technology. But more importantly, changing global political dynamics, especially the rise of China, provided new impetus to the US to change these regimes to include others, such as India, with which there was common interest regarding China.  

At a practical level, India’s development of the GSLV Mk III, capable of launching four-tonne satellites into geostationary orbit, relieves India of dependency on foreign players to launch its heavy satellites. This has been an expensive proposition: the launch cost of heavy payloads is estimated to cost upwards of Rs 400 crore. A successful GSLV Mk III test can make India somewhat self-reliant in launching heavier communication satellites. Some of the other launchers in the market, such as Ariane 5 and the Delta IV Heavy, can launch even heavier payloads, of course.

India’s capability to launch heavy satellites also has significant positive commercial spin-offs. This will make India an important player in the multibillion-dollar global satellite launch market, making India a cost effective and reliable partner for heavy satellite launches, generating additional revenue for ISRO. Given that the future satellite launch market will have a big focus on heavy communication satellites, India has a strong incentive to master this launch vehicle, as it has done with its PSLV. The heavy launcher has the potential also to be used in a future Indian human space programme, even though it is not clear that a political decision on whether India wants to do one or not has been taken yet. Lastly, the enhanced launch capability builds up India’s potential to undertake deep space exploration more seriously.


Rajaram Nagappa, Visiting professor, National Institute of Advanced Studies, Bengaluru

On the heels of the successful launch of the South Asia Satellite on May 5, 2017, ISRO is gearing up for the maiden flight of its four-tonne class GSLV Mk III vehicle in early June. The vehicle will launch the 3,200-kg GSAT 19 satellite, which will carry communication, scientific and experimental payloads. The launch will bring to fruition the efforts put in by the scientists and engineers of ISRO in realising the GSLV Mk III. Having said that, the vehicle development has been substantially delayed from the initial estimate. The first launch of GSLV Mk III was expected to happen in the 2011-2012 timeframe as per the Department of Space Annual Report of 2009-2010.

The GSLV Mk III lower stages are derived from proven technologies of PSLV and GSLV. The cryogenic third stage, C25, however, uses elements of technology different from the cryogenic upper stage (CUS) of the GSLV Mk II. The CUS employs a staged combustion cycle. The C25 on the other hand employs a gas generator cycle. The gas generator cycle has a lower specific impulse (of the order of 4%) but is less complicated and provides a certain level of flexibility in testing. The lower performance with lesser complexity of the stage engineering seems to be a conscious trade-off. The GTO capability of the launcher is now pegged at four tonnes.

It is seen from newspaper reports that integration of the vehicle has commenced. The GSLV Mk III D1 launcher [that will be launched on June 5] will carry the 3,200-kg GSAT-19 satellite (with Ku and Ka band payloads), scientific experiments and an indigenous lithium-ion battery. Knowing the ISRO culture of documentation, strict adherence to laid out processes and the rigour of design/flight readiness reviews, one can expect a successful mission outcome.

However, there is still a gap between transponder requirement and availability. To bridge the gap, heavier satellites carrying more number of transponders as well as increase in launch frequency will be called for. S. Chandrashekar has studied the international communication satellites launched during 2005-2015. His findings indicate that 12% of the satellites fall in the <2,500-kg category; 30% in the 2,500-4,200-kg category; 27% in the 4,200-5,400-kg category; and 31% in the very heavy 5,400+ kg category. This trend is witnessed in ISRO satellites as well. Of the twelve GSATs flown since 2010, five are in 3,000+ kg category. The GSAT-11 under assembly at the ISRO Satellite Centre weighs 5,700 kg and is beyond the GSLV Mk III’s capability. The following suggestions are pertinent in this regard:

  • Close GSLV Mk II after GSLV Mk-III enters operational phase
  • Increase Mk-III production capacity through an ISRO plan for involving industry in a significant way in space production/operation activities
  • GSAT-19 carries a bus system experiment in electric propulsion. Substitution of chemical propulsion with electric propulsion in spacecraft must be done on priority.
  • Growth options of GSLV Mk III must be exercised

Jayant Murthy, Senior professor, Indian Institute of Astrophysics, Bengaluru

Scientists always want bigger and better. The primary mirror for the Thirty Meter Telescope (TMT) is 30 metres wide, with even larger mirrors in the offing. Contrast this with the 2.4-metre telescope on the Hubble Space Telescope, with a mirror weight (alone) of 800 kg and a spacecraft weight of 11 tonnes. Our own flagship Astrosat spacecraft has a mass of only 1.6 tonnes and the Ultraviolet Imaging Telescope has a mirror diameter of only 35 cm. Clearly, we have much ground to cover. The additional lifting capacity of the GSLV Mk III launcher will let us start planning for more ambitious missions with larger mirrors and more advanced instrumentation. The greater lifting power also allows for planetary missions with more sophistication than the relatively underpowered instruments on Chandrayaan and the Mars Orbiter Mission.

The Indian astronomy community has several goals that require more than the PSLV. The first might be a successor to Astrosat. We have now begun to exploit the capabilities of the Astrosat mission and are already missing opportunities because we don’t have the larger and more specialised instrument – perhaps an ultraviolet spectrograph – to follow-up on some of the exciting discoveries. We are expanding heavily into solar physics, with the National Large Solar Telescope (NLST) and the complement of experiments on Aditya, a solar observatory. A possible follow-up might be an observatory to observe the solar poles, but this requires more energy and will not be possible with the PSLV. Finally, there has been considerable interest in Mars since the discovery that there was once large amounts of water on the planet and that it is possible that primitive life may be hiding somewhere on the surface.

Unfortunately, these require a commitment to science that has not been shown by ISRO or the government in the past. Investment in an energetic space exploration pushes the boundaries of feasibility and seeds the revolutions of the future. A dedicated science plan involving the GSLVs and their eventual successors would pay rich dividends.


R. Ramachandran, journalist, Frontline

The new beast from ISRO’s stable, the GSLV Mk III a.k.a. LVM-3, standing on the launchpad at the Satish Dhawan Space Centre in Sriharikota to be launched on June 5, is a testimony to the decades of perseverance of ISRO scientists to master the complex cryogenic combustion technology. ISRO’s decision in the late 1980s to abandon its indigenous cryogenic engine development programme – ready in 1984 with a 15-volume report for a 12-tonne-thrust engine, and to acquire the technology from Russia instead – has proved costly. The resulting setback was for about a decade and a half. This is really significant if you are looking to capture a share of the global market in the heavier than INSAT-class satellite-segment.

ISRO’s internal think-tank, responsible for tracking technical trends and international affairs and nurtured by former ISRO chief Satish Dhawan, had warned that significant hurdles to technology acquisition would crop up through the Missile Technology Control Regime (MTCR), constituted in 1987. ISRO paid no heed to it and went ahead to sign a deal with Glavkosmos. The latter, as we now know, subsequently reneged on the agreement under the pressure of sanctions from the US, which had masterminded the MTCR.

Having acquired seven off-the-shelf engines from Russia, and having spent lot of money on it, the route to indigenous development of the cryogenic engine became defined almost as a fait accompli. Developing the GSLV Mk I provided firsthand experience in handling cryogenic propellants, with feed and monitoring systems suited to the design of the Russian engines. However, the vehicle turned out to have a success rate of one in three – so not very successful.

The indigenisation (or reverse engineering) of the cryogenic stage that followed – based on data and drawings that had been acquired before the deal imploded – was not easy, especially because of the complex staged combustion cycle (SCC) that the Russian design used, instead of the gas generator cycle (GGC) that ISRO scientists were familiar with. Nonetheless, the rocket that was built as a result, the GSLV Mk II, achieved a success rate of 80% and stood as testimony to the skill of ISRO scientists to master difficult and diverse technologies.

However, the Mk III is a different animal altogether. For its CE20 engine, ISRO decided to return to the GCC route because of the flexibility of control it offered. Engineers also did away with the twin vernier engines, used to control the trajectory of the rocket while the main engine provided the thrust, that the Russian design had persisted with.

So, the long and complicated route that ISRO has taken to achieve its goal, whose beginnings date to 1971, was like – as a Tamil saying goes – touching the nose by taking the hand around the head instead of doing it straight. If only the organisation had not ignored the warnings from within its ranks, it might have got to this stage a while ago. This lesson also underlines the importance of understanding international geopolitics in science and technology affairs.


Gagan Agrawal, analyst, Northern Sky Research (India); ex-ISRO (launch vehicle technology)

Demand and supply is of key importance in the open market for commercial satellite launches, and commercial spaceflight is an area in which ISRO aspires to do well in the medium to long term. The Mk III, with its ability to lift over 3,500 kg to the GTO, assumes pole position in ISRO’s plan to cater to both domestic and international markets.

From a domestic perspective, there are two principal problems. First: Being able to launch payloads of 3-4 tonnes will reduce India’s dependence on foreign nations to launch home-built satellites. Currently, the European company Arianespace is being used to launch many of India’s GTO satellites. Second: the communications market has been limited by the number of transponders available in Indian skies. So focusing on increasing the Mk III’s payload size to 4-5 tonnes will be key in determining whether ISRO can push the transponder envelope to greater than 48 per satellite and launch them onboard a domestic vehicle in the future. Overall, the domestic capability would augur well for ISRO – not just with respect to the 40-50% savings on launch costs but also on the R&D and human capital gained from the project.

From an international perspective, the commercial market traditionally supports a maximum of three players, with a few peripheral players. This leaves little room for the GSLV MK II or even the MK III to compete. Currently, the world’s main launch vehicles are Ariane 5, Soyuz, Falcon 9 and ULA’s Delta/Atlas. Newer vehicles anticipated from the stables of Arianespace and Blue Origin and the market is getting more crowded. So with the bulk of the satellite communication launch demand today served by Ariane 5 and Falcon 9, it is their space that the Mk III will have to penetrate. It remains to be seen if this will happen – especially by also remaining as a lower-cost option. For starters, a good success rate like its predecessor, the Mk II, will go a long way in establishing international confidence in the Mk III to launch medium- to high-range communications satellites.

And in the aftermath of such success, ISRO is bound to place fewer orders to launch geosynchronous satellite launches that have been historically addressed by Arianespace. Its rise could also signal the emergence of a new, competitive option that fledgling space nations could look up to, other than the US, Russia, Europe and China.

  • The Wire

    Thanks, ghostthoughts. Both sources are official (ISRO), so we’ve gone with the more detailed and recent one.