CHENNAI: Indian space science is waiting at the threshold of a new phase of mega satellite launches and exploration as the countdown for the GSLV-D5 rocket launch began at 11.50am on Sunday. Twenty-nine hours later, at 4.50pm on Monday, the rocket carrying telecommunication satellite GSAT-14 will lift off from Sriharikota , 100km north of Chennai.

GSAT-14, which weighs 1, 982kg , will be used for telecast and telecommunication.

What makes the launch crucial for the nation is the use of an indigenous cryogenic engine as the upper stage. The first attempt to use an indigenous cryogenic engine on April 15, 2010 to power GSLV-D3 was a failure. With only one more Russian cryogenic engine left in the Isro arsenal, success of the indigenous technology using oxygen and hydrogen in extreme low temperatures as the fuel will propel several big ticket future missions including a manned project to space.

Isro senior scientists led by chairman K Radhakrishnan are monitoring GSLV-D5, whose strap-boosters started getting fuelled soon after the countdown. Liquid propellants are being filled into the second stage. Liquid hydrogen and liquid oxygen, which fuel the cryogenic engine will be filled around 9am on Monday. Scientists at the Satish Dhawan Space Centre told TOI that the rocket's health and weather conditions were fine.

India needs cryogenic engines to launch GSLVs that can carry payloads weighing more than three tonnes, which hold the key to future of telecommunication and space exploration. GSLV-D5 weighs 414 tonnes.

Since 1994, India has had 23 consecutive successes with the Polar Sateliite Launch Vehicles (PSLVs), an improvised version of which was used for Chandrayaan-1 in August 2009. However, PSLVs can carry only payloads weighing up to 1.5 tonnes to a geosynchronous transfer orbit (a highly elliptical orbit with the nearest point to earch about 200km and the farthest 42,00km) , and up to 3.5 tonnes to a low earth orbit of about 200km from earth. GSLV can carry payloads weighing 2.5 tonnes to a geosynchronous transfer orbit, and up to 5 tonnes to a low earth orbit.