SRIHARIKOTA: In October 2008, a light PSLV lifted off from here carrying the 1,380kg Chandrayaan-1. Eleven years later, on Monday, Isro employed a GSLV-MkIII to carry Chandrayaan-2 , which weighed 3,850kg.

Impressive? Yes, but Isro will have to look at developing newer rockets to carry much heavier payloads as satellites and interplanetary probes of future. As it plans missions to Moon, Mars, Venus and even Sun, the space agency’s engineers and scientists are working on upgrading its fleet of rockets.

From its humble beginning in a fishing village in Thiruvananthapuram in the 1960s, Isro has come a long way. So far it has had four classes of rockets—SLV, ASLV, PSLV and GSLV. And GSLV-MkIII is the heaviest rocket it has built.

GSLV’s success also meant that Isro, which toiled for more than 20 years, has mastered the cryogenic technology. “After all the hard work, we can proudly say we’ve mastered the complex technology for the cryogenic stage,” said V Narayanan, director LPSC.

Chandrayaan-2 was the first spacecraft GSLV-MkIII put into space after being declared operational in November last. And with some tweaks, it is slated to carry Indian astronauts for the human spaceflight programme in 2022.

“Cryogenic engine is the future,” Narayanan says. And, if not for all the sanctions placed on India, Isro would have had the cryogenic technology operational as early as 1999-2000. But lobbies from different parts of the world saw the project got delayed.

While some call GSLV-MkIII ‘Bahubali’, but it compares poorly with other heavy-lift rockets in the world. Isro’s heaviest rocket is rated to carry about 8,000kg to a low earth orbit (LEO) and half of that to higher orbits; SpaceX’s Falcon-9 can carry nearly 23,000kg. Falcon Heavy can put a mass of nearly 64,000kg into LEO, while the French Ariane-5 can carry nearly 21,000kg. While these are modern launch vehicles, the US space shuttle, which has been retired, could carry more than 27,000kg.

But GSLV has been improving, say scientists. “In this launch, we increased the weight by 400kg compared to the June 2017. In the next mission, we’ll increase the capacity by another 500kg,” Isro chairman K Sivan had said after the launch of GSAT-29 in November 2018.

