Isro to launch its fifth satellite in GSAT series

Mission to increase transponder capacity by great extent.

A communication satellite — GSAT-5 Prime — is set to be launched aboard the Geo-Synchronous Satellite Launch Vehicle (GSLV-F06) at 4 pm on December 20. The 30-hour countdown to the launch will begin on December 19. The Indian Space Research Organisation (Isro) is terming it a crucial mission, as it will greatly boost India’s transponder capacity.

This is the fifth satellite to be launched in the GSAT series. The exclusive communication satellite will augment the communication services presently provided by the Indian National Satellite (INSAT) system. The satellite will be launched from the Satish Dhawan Space Centre SHAR, Sriharikota.

GSLV-F06 has three stages, with the first core stage powered by solid propellants. There are four strap-on booster motors, fuelled by liquid propellants, strung around the first stage. The second stage uses an engine powered by liquid propellants. The third upper cryogenic stage is from Russia. The GSAT-5P has a lift-off weight of 2,310 kg.

The Russian cryogenic stage being used is more powerful than those used in the previous GSLV missions. This is the sixth GSLV mission that will use a Russian cryogenic engine. The GSLV weighs 418 tonnes and is 51 metres long.

During the 30-hour countdown, the second stage and strap-on boosters will receive the liquid propellants beginning T-minus 30 hours, the cryogenic propellants — liquid hydrogen and liquid oxygen that are at extremely low temperatures — will be pumped into the upper Russian cryogenic stage only from T-minus six hours.

S Satish, director of Publications and Public Relations, Isro, told Business Standard, the GSAT-5P will “provide a continuity to services offered by the INSAT system”. It has 36 transponders, including 24 C-band transponders and 12 extended C-band ones. The transponders are expected to aid in telecasting television programmes, and also help in the delivery of telemedicine and tele-education. It will also boost the telephonic services. The GSAT-5P weighing 2,310 kg at lift-off will carry 24 normal C-band and 12 extended C-band transponders.

This will also be the heaviest payload to be launched by a GSLV. The launch mission will last 1,140 seconds, and at the end of it the cryogenic stage will inject the GSAT-5P into orbit. ISRO Satellite Centre, Bangalore, has built the GSAT-5P. The satellite is expected to have a mission life of 13.7 years.