Explained: Behind Chandrayaan-2’s GSLV Mk-III rocket that developed a glitch today

Amitabh Sinha
Indian Space Research Organization (ISRO)’s Geosynchronous Satellite Launch Vehicle (GSLV) MkIII carrying Chandrayaan-2 stands at Satish Dhawan Space Center after the mission was aborted at the last minute at Sriharikota (AP)

The GSLV Mk-III rocket, which developed problems just ahead of the launch of the Chandrayaan-2 mission on Monday morning, is supposed to be ISRO s next-generation launch vehicle, designed to carry heavier payloads deeper into space.

A result of over three decades of indigenous research and development, after India was denied the cryogenic technology in the early 1990s, GSLV Mk-III has been used in only two launches till now. It carried and deployed the GSAT-19 communication satellite on June 5, 2017, and then the GSAT-29 communication satellite on November 14 last year. Earlier, it had an experimental flight in 2014.

Built as the rocket for the future, as ISRO aims to put bigger and bigger payloads, and probe deeper into space, GSLV Mk-III has an interesting history and a story of three decades of hard work in taming the cryogenic technology. Cryogenic is the science relating to the behaviour of materials at very low temperatures. It is essential for a rocket-like GSLV Mk-III, and it was denied to India by the United States in the early 1990s, forcing ISRO to go for indigenisation.

Amongst all rocket fuels, hydrogen is known to provide the maximum thrust. But hydrogen, in its natural gaseous form, is difficult to handle, and therefore not used in normal engines in rockets like PSLV. However, hydrogen can be used in liquid form. The problem is hydrogen liquefies at very low temperature, (nearly 250-degree Celsius below zero.) To burn this fuel, oxygen also needs to be liquid form, and that happens at about 90-degree Celsius below zero. Creating such a low-temperature atmosphere in the rocket is a difficult proposition because it creates problems for other material being used in the rocket.

Built as the rocket for the future, as ISRO aims to put bigger and bigger payloads, and probe deeper into space, GSLV Mk-III has an interesting history and a story of three decades of hard work in taming the cryogenic technology. (Source: ISRO)

ISRO had planned the development of a cryogenic engine way back in the mid-1980s when just a handful of countries — the United States, the erstwhile USSR, France and Japan — had this technology. To fast-track its development of next-generation launch vehicles — the GSLV programme had already been envisioned by then — ISRO had decided to import a few of these engines. It had discussions with Japan, US and France before finally settling for Russian engines. In 1991, ISRO and the Russian space agency, Glavkosmos, had signed an agreement for the supply of two of these engines along with transfer of technology so that the Indian scientists could build these on their own in the future.

However, the United States, which had lost out on the engine contract, objected to the Russian sale, citing provisions of Missile Technology Control Regime (MTCR) that neither India nor Russia was a member of. MTCR seeks to control the proliferation of missile technology. Russia, still emerging from the collapse of the USSR, succumbed to the US pressure and cancelled the deal in 1993.

In an alternative arrangement, Russia was allowed to sell seven, instead of the original two cryogenic engines but could not transfer the technology to India. These engines supplied by Russia were used in the initial flights of first and second-generation GSLVs (Mk-I and Mk-II). The last of these was used in the launch of INSAT-4CR in September 2007.

But ever since the cancellation of the original Russian deal, ISRO got down to develop the cryogenic technology on its own at the Liquid Propulsion Systems Centre at Thiruvananthapuram. It took more than a decade to build the engines and success did not come easily. In 2010, two launches of second-generation GSLV rockets, one having the Russian engine and the other indigenously developed, ended in failures.

Spectators leave after the Chandrayaan-2 mission was aborted at Sriharikota (AP)

The big success came in December 2014 with the experimental flight of third-generation (Mk-III) GSLV containing an indigenous cryogenic engine. This mission also carried out an experimental re-entry payload, that ejected after reaching a height of 126 km and landed safely in the Bay of Bengal.

After that, there were two successful launches of GSLV Mk-III in 2017 and 2018. Chandrayaan-2 was it’s biggest and the most keenly-awaited launch. But it will now have to wait.

As of now, it is not clear how serious the problem detected on Monday morning is. Though ISRO has been tight-lipped about the nature of the problem, there are indications that it could relate to the cryogenic upper stage.