Hyderabad: A crack in the main feed line of the rocket carrying Indian astronaut Shubhanshu Shukla and three others to the International Space Station (ISS) led to a rescheduled launch and averted what could have been a "catastrophic failure," ISRO chief V Narayanan said on Tuesday.

Speaking at the Convocation Address of Osmania University, Narayanan recounted the events leading up to the Axiom-4 (Ax-4) mission, which was initially set to launch on June 11. The flaw was discovered on June 10 by ISRO scientists stationed at the Kennedy Space Center in the United States, prompting them to raise serious concerns.

"There were 14 questions asked and none of the questions were answered satisfactorily, including where the leak was. It was not identified. We demanded the entire correction, because we were very clear. Because I have been working in that area for 40 years, I know what is the difficulty if a rocket takes off with a leak," Narayanan, who also serves as Secretary, Department of Space, said.

Following the Indian Government’s insistence, a formal note was submitted by the Indian team, which led to a complete correction of the leakage. The mission was eventually delayed and successfully launched on June 25.

"Later, the first launch (on June 11) was called off after the Indian scientists inspected and found a crack in the main feed line," he added.

"If the rocket would have taken off (with the leak), it would have been a catastrophic failure. Based on the insistence of Indians, the Indian education system, the training of ISRO, the rocket was corrected. Today we have accomplished a safe mission, not only Shubhanshu Shukla, along with him three more international astronauts," Narayanan said.

Shubhanshu Shukla returned to India early Sunday after his milestone voyage to the ISS as part of the private Axiom-4 mission. The mission, which lifted off from Florida on June 25 and docked with the ISS on June 26, concluded with a safe return to Earth on July 15.

Alongside Shukla, the crew included veteran American astronaut Peggy Whitson, Slawosz Uznanski-Wisniewski from Poland, and Tibor Kapu of Hungary. During the 18-day mission, Shukla conducted more than 60 scientific experiments and participated in 20 outreach sessions.