CHENNAI : The first unmanned test flight of Indian rocket Geosynchronous Satellite Launch Vehicle (GSLV), as part of the country's human space mission Gaganyaan, will not happen this year, said officials.The Indian Space Research Organisation (ISRO) had planned the first of the two test flights later this year."The first flight of the rocket as part of Gaganyaan mission will not happen this year (2020)," a senior ISRO official, speaking on the condition of anonymity, told IANS.While the actual reason for the delay is not known, perhaps the Covid-19 lockdown had its impact on the first test flight.In his address at the 70th Annual General Meeting and National Conference on "Recent Developments in Aerospace and Defence Technology" organised.