By IANS,
Chennai : The countdown to the launch of a 50-metre, tall, 416-tonne rocket with an Indian cryogenic engine to inject an advanced communication satellite in the geo-synchronous orbit has started at the Sriharikota spaceport in Andhra Pradesh, a space agency official said Wednesday.
“Filling of liquid propellants in the four strap-on motors (42 tonnes each) that will be hugging the rocket is set to begin soon. Fuel filling of the second stage (40 tonnes) got over recently,” Indian Space Research Organisation (ISRO) director S.Satish told IANS from Sriharikota.
The countdown for the blast off for the Rs.330 crore mission (rocket Rs.180 crore, GSAT-4 satellite Rs.150 crore) started Wednesday morning at 11.27 a.m.
The propellant filling for the Indian designed cryogenic stage (12.5 tonne) will start five hours before the rocket launch and will get over minutes before the actual blast off.
The first stage with 138 tonnes solid fuel is all ready to be fired up.
“All activities are progressing smoothly without any hitch,” he added.
The rocket is expected to blast off at 4.27 p.m. Thursday to deliver the 2.2-tonne GSAT-4 satellite into the geosynchronous transfer orbit (GTO).
The notable aspect of this launch is that the rocket will be powered by ISRO designed and built cryogenic engine (development cost around Rs.350 crore). If the cryogenic engine performs as expected, India will become the sixth country in the world to design and develop the cryogenic technology.
The two other unique features of the rocket are its larger composite payload fairing or heat shield and the advanced telemetry systems and mission computers.
After a gap of several decades, the Indian space agency has reverted to fibre reinforced plastic (FRP) heat shield for its rocket.
The GSLV-D3 rocket has a bigger heat shield – four metre diameter – as compared to the earlier rocket versions whose heat shield were of 3.4 metre diameter and were made of aluminium alloy metal.
“In order to reduce the rocket weight with a bigger heat shield, ISRO has decided to use a FRP heat shield. A bigger heat shield will provide more space for carrying a bigger payload,” an ISRO official told IANS on the condition of anonymity.
According to him, a bigger equipment bay will not constrict ISRO’s satellite building team in their ventures.
Heat shield made of FRP is not new to ISRO as it was used in its satellite launch vehicles (SLV) earlier.
However, the space agency changed to metallic heat shield when it designed its workhorse rocket polar satellite launch vehicle (PSLV) and also in GSLV.
“The increase in heat shield size is made with future launches in mind. While the heat shield of SLV was just one metre diameter, here it is four metres. The challenge was to make the mould,” the ISRO official said.