India Space Research Organisation's attempts to raise its stature in the global satellite launch business will be put to a significant test on Monday (August 19) when it launches its Geo-synchronous Satellite Launch Vehicle GSLV-D5 with an indigenous cryogenic engine.

GSLV-D5 is expected to put in orbit GSAT-14, an advanced communication satellite weighing almost two tonne. If successful, it will announce to the world that ISRO has finally overcome all technology barriers to put heavy communication satellites in orbit.

The global satellite launch market is large and satellites of varying sizes are launched depending on the tasks they are expected to perform. Remote sensing satellites are lighter and are placed in polar orbits (those where the satellites do not move in tandem with earth's rotation and hence are not suitable for communication purposes). These satellites weigh between a few hundred kilos to about a tonne.

Communications satellites are heavier weighing between two and five tonne - and they are placed in geo-synchronous transfer orbits where the satellite moves in tandem with earth's rotation. Thus the satellite service is available to users throughout the day.

So far, ISRO has mastered the art of putting smaller satellites in space. Its Polar Satellite Launch Vehicle (PSLV) has had 23 consecutive successful launches and has put 63 satellites in precise orbits (23 Indian and 35 foreign satellites). PSLV's cost efficiency and reliability has been clearly established in this segment.

But the same cannot be said about ISRO launching communication satellites - which is where big business is. ISRO's attempts to break into that market with GSLV has been met with repeated failures - both technological and operational. The critical element of GSLV is the cryogenic engine, one that is powered by liquid hydrogen and liquid oxygen, stored at very low temperatures.

India had initially tied up with Russia for supply of these engines and got seven of them in the 1990s. But the US then objected to the deal on the grounds that it violated the Missile Technology Control Regime. This left ISRO with no choice but to develop the engine on its own (of course with some Russian help). Only space agencies of the US, Japan, China, Russia and the European Space Agency have overcome this technology barrier.

Mastering cryogenic technology has proved a tough challenge for ISRO. It has so far attempted seven GSLV launches (six with Russian cryogenic engines and one with the engine it developed on its own) and four of them have failed. What is worrisome is that in each instance the failure was for a different reason - fabrication issues, quality issues and of course, the failure of the locally developed cryogenic engine itself.

GSLV-D3 which carried the indigenous cryogenic engine blew up in the sky after failing to perform, sending a clear message that mastering the cryogenic technology is a pre-requisite for ISRO to dream of any meaningful presence in the global satellite launch business. In the meantime ISRO continued to use the services of the European Space Agency to launch its heavier communication satellites - the INSAT series.

After the GSLV-D3 failure in April 2010, ISRO went back to the drawing board and revisited the entire design of the GSLV - not only the indigenous cryogenic engine. Having learnt from the failures of previous launches and extensive testing, large scale modifications have been made in GSLV-D5.

According to senior ISRO officials the changes include redesign of the shroud portion of the launch vehicle to protect the cryogenic engine better, reinforcement of the wire tunnel to withstand higher pressure, improvement to the aerodynamic characteristics of the launch vehicle and re-designing of the fuel booster turbo pump (whose failure caused one of the earlier setbacks).

Most importantly, ISRO has, for the first time, carried out high altitude testing for the ignition of the cryogenic engine by simulating vacuum conditions on the ground. This, according to the official, is a critical element of the preparation.

ISRO, till now, did not have the facilities to conduct this test. "We have taken a lot care this time to ensure that GSLV-D5 launch is successful," the official said.

The 49 meter tall GSLV-D5 weighing 414 tonne has been moved to the launch pad at ISRO's space port on the east coast in Sriharikota, some 90 minutes drive from Chennai. The count down for the launch will begin on August 18 at 11.50 am.

When GSLV-D5 finally lifts off at 4.50 pm on Monday, so will the hopes of a billion Indians whose pride will move a notch higher when ISRO announces that it has overcome a significant technology barrier and broken into a market that is an exclusive domain of just a handful of countries.