Mr Somanath said he expects Ms Williams to return on the Boeing Starliner capsule.
Astronaut Sunita Williams' mission may have been prolonged because of glitches in the Boeing Starliner capsule but she is in the "safest possible place in space" and there is no cause for concern, ISRO Chairman S Somanath has said.
Speaking exclusively to NDTV on Tuesday, Mr Somanath was asked whether he had any concerns about Indian astronaut Group Captain Shubhanshu Shukla going to the International Space Station (ISS) early next year, given that Ms Williams - an Indian-origin astronaut - has been there for two months on what was supposed to be a mission lasting approximately a week.
"That has nothing to do with the ISS. Apart from Ms Williams, there are eight other astronauts, many of whom have been there for a long time. Their plan of return is with some other missions that are yet to be scheduled. The only question with Ms Williams is that she had planned for a week-long mission and should have returned aboard the Boeing Starliner, which has faced some technical issues," the ISRO chief said.
"But they are in the safest place possible in space, which is the International Space Station, so there is no cause for concern. There is definitely a way to bring them back. Either on the Starliner or some other capsule, two of which are already there. But to bring back a crew trained on one craft with certain specifications to another... switching is not easy, it has never been done before. There are technical issues to be addressed which can be done by the appropriate people," he added.
Mr Somanath emphasised, however, that his expectation is that Ms Williams and her fellow astronaut on the Starliner mission, Barry "Butch" Wilmore, would return to Earth on the Boeing capsule itself.
"They may delay it to make sure that the Starliner becomes cleared for return," he said.
Ms Williams and Mr Wilmore took off aboard the Boeing Starliner in June and have been at the ISS since the sixth of that month. The Starliner has faced glitches in the propulsion system following a series of helium leaks and the astronauts, NASA and Boeing are working on a fix to get them back to Earth.
Group Captain Shukla will be on the Indo-US Axiom-4 mission to the International Space Station, which is expected to launch in early 2025. According to ISRO, the Gaganyatri will undertake selected scientific research and technology demonstration experiments on board the ISS as well as engage in space outreach activities. The mission will be led by Dr Peggy Annette Whitson, who is America's most experienced astronaut.