India is set to launch a geo-synchronous communication satellite, GSAT-12, into orbit using the indigenously built launch vehicle, the Polar Satellite Launch Vehicle or PSLV, on the 15th of July, 2011. The launch for mission, named the PSLV-C17/GSAT-12 Mission, was cleared by the Launch Authorisation Board (LAB) on the 12th of July, 2011. The launch is cleared for 1648 hrs, IST or 1118 hrs EST from the Satish Dhawan Space Center, Sriharikota Range. The countdown has already commenced.
The countdown period will give ISRO a chance to perform checks on the operations of the liquid propellant second (PS2) and fourth stage (PS4) of the PSLV rocket. It will also provide the opportunity to conduct mandatory tests on spacecraft payload, i.e. the GSAT satellite, and on the batteries. Simultaneous checks will be conducted on the ground at the launch site and at various monitoring stations for readiness and network response. (Source: ISRO Press Release)
The Rocket and the Payload
The GSAT-12 satellite will be launched into an orbit with a perigee (i.e distance of closest approach to Earth) of 284 km and apogee (i.e. distance at farthest point) of 21,000 km. The Satellite weighs in at 1410 kg and is believed to cost Rs. 80 crore (about $18 million). The PSLV, along with the fuel, costs Rs. 110 crore (about $24 million).
The PSLV rocket is being used this time against the more powerful GSLV, because of the moderate weight of the payload and the nearness of the orbit. The main difference between PSLV and GSLV is the firing off of the main motor and those strapped on. For the PSLV, the core motor fires, followed by the strap-on thrusters, which ignite after lift-off. For the GSLV, the secondary thrusters fire first and about four and a half seconds later, the core rocket fires for lift-off. The GSLV has a cryogenic engine and can carry heavier payloads to higher orbits, since the engine can deliver more thrust. GSLV was the vehicle used for delivering the INSAT satellites into orbit.
The GSAT-12 will be a communication satellite, loaded with Ext-C band transponders. This will be used primarily for telephone purposes. There is no current resolve to use this for intelligence purposes.
The PSLV C-17 launch was absolutely successful and right on time. The GSAT-12, to be used primarily for tele-medicine, is now being put into orbit. The ISRO team deserves a round of applause.