New Delhi, Sept. 18 -- Four astronauts selected for the country's first human spaceflight will return from Russia next March and undergo training modules designed by the Indian Space Research Organisation (Isro) for the ambitious mission slated for December 2021. While their training in Russia will help them get acquainted with the basics of a human spaceflight - the US, Russia and China are the only three countries to have conducted such missions - the four astronauts will undergo mission-specific training back home. "The four astronauts, who had been selected from a pool of Indian Air Force pilots, are currently undergoing basic training in GCTC (Yuri Gagarin Cosmonaut Training Centre) in Russia. They will be back by March next year. They will then receive specific training in India, for which the simulators have been defined. These are the areas where the industry will be contributing in a rich way to realise the simulators," Dr Unnikrishnan Nair, director, Human Spaceflight Centre of Isro, said....