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ISRO rocket launch today, all eyes on cryo engine
Shubhadeep Choudhury/TNS

Crucial mission

  The 49.13-metre GSLV-D5 rocket carrying telecommunication satellite GSAT-14 will lift off from Sriharikota near Chennai at 4.50pm on Monday

  The mission assumes more significance as the indigenously developed cryogenic upper stage engine will be flight-tested for the second time by ISRO

  The first flight-testing of an indigenous cryogenic upper stage engine in the GSLV-D3 mission failed on April 15, 2010

  The next GLSV flight with a Russian cryogenic stage also ended in failure in December 2010

Bangalore, August 18
A 29-hour countdown began on Sunday for the crucial launch of the heavylift GSLV (geosynchronous satellite launch vehicle) rocket -- which will also be the flight-testing of the second indigenous cryogenic upper stage (CUS) engine -- from Sriharikota spaceport.

The 49.13-metre GSLV-D5 will place the 1,982 kg GSAT-14, a communication satellite, into geosynchronous transfer orbit (GTO) after a 17.8-minute flight. After reaching the geosynchronous transfer orbit, GSAT-14 will use its own propulsion system to reach its geostationary orbital home and will be stationed at 74° East longitude to provide various satellite-based communication services to the country, including tele-education and telemedicine.

The first flight-testing of an indigenous cryogenic upper stage engine three years ago was a failure. GSLV-D3 -- powered by an indigenous CUS and carrying communication satellite GSAT-4 (2,220 kg) -- had deviated from its path and gone out of control shortly after lift-off on April 15, 2010.

Russsia, while it sold some cryogenic engines to India, refused to give the technology in the wake of pressure from the USA, which felt India could use the technology to develop long-range missiles. For two decades, ISRO scientists have been trying to develop the technology and tomorrow may well be the day when their hard work will finally pay off.

Heavylift GSLV rocket
Heavylift GSLV rocket

Monday’s launch is slated to take place from the ISRO spaceport at Sriharikota near Chennai at 4.50pm. Propellant filling for the second liquid stage was in progress at the time of filing of this report.

An ISRO official said that taking into account “the experiences” of the previous GSLV missions, “end-to-end design of GSLV and indigenous cryogenic stage systems have been re-examined and modifications have been implemented wherever required”.

Changes carried out in the launch vehicle include redesigning of the lower shroud which protects the cryogenic engine during atmospheric flight, redesigning of the wire tunnel of the cryo stage to withstand larger forces during flight, revised aerodynamic characterisation of the entire launch vehicle and inclusion of video imaging system to monitor lower shroud movement during various phases of flight.

As for the indigenous cryogenic upper stage engine, its fuel booster turbo pump (FBTP) - the malfunctioning of which had resulted in the failure of GSLV D3 - has been redesigned taking care of the expansion and contraction of the bearings and casing at cryogenic temperatures.

The ignition system of the engine has also been modified to ensure smooth and sustained ignition for main engine (ME), steering engine (SE) and gas generator (GG). During the flight, the CUS engine will fire for a nominal duration of 720 seconds.

GSLV is a three-stage launch vehicle with solid, liquid and cryogenic stages. It is designed to inject two tonne class of communication satellites to the geosynchronous transfer orbit (GTO). The four liquid strap-ons as well as the second stage of the rocket use storable liquid propellants.





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