It's only for the second time ever that a Polar Satellite Launch Vehicle is being used to loft a communication satellite, the first one being Kalpana-1 in 2002.
Bangalore-headquartered ISRO opted for this step as there is a large unfulfilled and pressing demand for communication transponders.
Communication satellites are launched on board GSLV or ISRO goes in procured launches overseas.
"But we wanted to create (transponder) capacity at the earliest. That's why we used the PSLV for the purpose (of launching a communication satellite), and achieve whatever is possible best possible by a PSLV with XL configuration. That's the most powerful configuration," ISRO Chairman K Radhakrishnan told PTI here.
The GSAT-12 "fast-track" satellite with a mass of 1410 kg, has 12 Extended C-band transponders. It is slated to be injected into space by PSLV-C17 after the launch from Sriharikota spaceport slated between 16.48 hours and 17.08 hours on July 15.
Similar PSLV, with extended strap-ons, was used for India's Chandrayaan-1 mission.
On the PSLV-C17/GSAT-12 mission cost, Radhakrishnan said, "Launch vehicle of PSLV of XL-class will cost about Rs 100-Rs 110 crore, and GSAT-12 will be about Rs 80 crore. The life of the satellite will be about 7-8 years."
Radhakrishnan said in the beginning of the 11th plan, ISRO had 211 transponders, and the target then set was to take it to almost 500 by March 2012, which is end of the plan period.
But except for 24 transponders added by GSAT-8 which was operationalised recently, ISRO had not been able to enhance these numbers since September 2007.
"During the period, most of our satellites have either completed their normal life or there were premature terminations," he said. "So, this resulted in the 211 becoming 175 now. There is a lot of unfulfilled demand to be met."
To meet this growing demand, Bangalore-headquartered ISRO is building GSAT-10 with 36 transponders and it would be launched by Arianespace from Kourou in French Guiana during March-April next year.
"We are also building another satellite GSAT-7 that will have a few more transponders," Radhakrishnan added.