Rocket to be equipped to carry satellites up to 2.5 tonnes.

Flush with the successful launch of the GSLV D6 on Thursday, the Indian Space Research Organisation (ISRO) is geared up to add more heft to the three-stage rocket to enable it to lob satellites weighing up to 2.5 tonnes into geosynchronous orbit.

ISRO scientists are confident that the indigenous Cryogenic Upper Stage (CUS) could be tweaked further to enhance the performance of the GSLV rocket. CUS which failed in 2010 scored its first success with the launch of the GSLV D5 last year.

The proposed modifications to CUS involve reducing the mass of the vehicle and augmenting the thrust. The GSLV D6, in its present configuration, is capable of carrying satellites up to 2.2 tonnes. The GSAT-6 communication satellite launched on Thursday weighed 2,117 kg.

By enhancing the capability of the GSLV, ISRO hopes to tap the market for commercial launch of satellites in the medium class category. “We have had a flurry of inquiries from abroad for commercial launches,” says K. Sivan, Director, VSSC. “The successful flight of the GSLV D6 has proved the robust design of CUS and the launch vehicle. It has given us the confidence to go ahead.”

Mission Director R. Umamaheswaran said the next priority would be to optimise the mass of CUS and increase the thrust. “With the GSLV D6, our efforts were focussed on proving the reliability of the engine rather than maximise its capability.” He said a series of tests would be carried out next year to upgrade CUS and enable it to handle satellites up to 2.5 tonnes.

“The requirement for commercial launch of satellites in the 2.2 to 2.5 tonne category is very high and ISRO has a few good offers. Once the GSLV becomes capable enough to handle satellites of this class, we expect to net more offers.” With the trend shifting towards satellites of lower weight, the demand for medium lift launch vehicles like the GSLV is likely to remain good at least up to 2025, scientists feel.

The project to add muscle to the GSLV also involves tweaking the liquid strap on boosters and the second stage liquid propellant engine and reducing the mass of the avionics bay package.