The 51-and-a-half hour countdown for the launch of India's seventh navigation satellite IRNSS 1G on board the launch vehicle PSLV C33 has begun this morning at 9.20 hrs at the Satish Dhawan Space Centre, Sriharikotta. The satellite is the final in the series of space fleet to establish India's own space technology-based navigation system to aid the air, maritime and surface transport. <br/><br/>The ISRO scientists have said, filling up of liquid fuel in the fourth stage of the launch vehicle PSLV C33 is going on now as part of the countdown process. Indian Regional Navigation Satellites System is aimed at self-reliance in space based navigation. <br/><br/>The satellite IRNSS 1G is similar in configuration to its six other peer satellites which are now in space. The rocket PSLV C33 with the passenger on board will undertake the journey in its extended version with strap on boosters, given the passenger satellite's weight and the orbital destination.