Chennai: The Geosynchronous Satellite Launch Vehicle GSLVD3, the first Indian rocket to be powered by a totally indigenous cryogenic engine, will blast off from the Satish Dhawan Space Centre at Sriharikota at 4.27pm on Thursday. The 416-tonne vehicle will carry GSAT-4, a 2,218-kg communication satellite, to be put in an orbit 36,000km from earth. The countdown for the launch began at 11.27am.