The countdown for the epoch making journey of India's latest 4-ton class rocket GSLV Mark III D-1, starts this evening. The 25-and-a-half hour countdown begins at 3.58 pm at the second launch pad of the Satish Dhawan Space Centre, Sriharikotta, the national spaceport. It will carry India's communications satellite GSAT-19 with the lift off mass of 3136 kg, to a geosynchronous transfer orbit within seventeen minutes after its ignition tomorrow at 5.28 pm.<br/> <br/>The satellite has transponders in Ku and Ka bands to augment communication infrastructure, with a mission life of ten years. For the ISRO's most powerful ever launch vehicle GSLV Mark III D-1, it will be the first ever development flight.<br/> <br/>AIR correspondent says, the indigenous development of the high thrust cryogenic engine is regarded as the result of the untiring efforts of Indian space community for about three decades, braving technology denials and design challenges.<br/> <br/>AIR correspondent reports that the GSLV Mark III D-1 mission is a path breaking event for the national space agency ISRO. This year, it has achieved many unique feats. They include the highest number of satellites that were put into orbit in a single mission and hurling of multiple satellites in different heights in a single launch.<br/> <br/>The GSLV MK III mission is set to be yet another important milestone after meeting its target. The rocket is 43.43 meters long, and weighs 640 tons altogether. All its three stages are of newer configurations. The GSLV Mark III D-1 is set to place the heaviest satellite ever to be launched from India.