Rediff On The NeT: India, US on par

Satellite technology: India, US on par

India is now on par with the United States in terms of satellite technology.

With the Polar Satellite Launch Vehicle-C1 putting the IRS-1D satellite into orbit on Monday, India took another giant step in achieving self-reliance in space technology.

From sounding rockets to one tonne-class satellites to low-earth orbits in less than 25 years is no mean achievement, as only a few countries possess launch vehicle technology.

The PSLV-C1/ IRS-1D mission represents India's technological self-reliance in designing and building state-of-the-art remote-sensing satellites and launching them from within the country, thereby reducing dependence on acquired launch which is becoming prohibitive.

India's remote-sensing satellites have already earned tremendous reputation through out the world. Images from the IRS-class satellites, which are among the most powerful civil ones, are being distributed worldwide.

The Indian rocket development programme, that began in 1963 with the setting up of the Thumba Equatorial Rocket Launching Station near Thiruvananthapuram, had to cross several hurdles and pitfalls before Monday's successful launch.

The Indian satellite launch vehicle programme has been a saga of ups and downs, unlike greater success achieved in satellite-building.

Starting with borrowed rockets, India quickly built up a family of sounding rockets of various diameters and the capability of launching satellites up to 200 kg to an altitude of 300 to 400 km for carrying out scientific experiments.

The launch vehicle programme, which took off in 1979, received a setback as the first experimental flight of Satellite Launch Vehicle-3 in July that year was only partially successful due to a jammed valve in the second stage control system. The next flight on July 18, 1980, saw the tiny payload of Rohini satellite placed in orbit.

Conceived in 1969, the SLV-3 was a 22-metre-long four-stage vehicle weighing 17 tonnes. After the successful second flight, there were two more SLV flights in May 1981 and April 1983 to place Rohini satellites with remote-sensing sensors on board.

The SLV-3 series gave valuable inputs for the vehicle and mission design, hardware fabrication, realisation of solid propellant technology, besides a host of other technologies for a subsequent generation of launch vehicles.

The ISRO moved into the next phase with the second generation Augmented Satellite Launch Vehicles, weighing about 40 tonnes and 23.8 metres tall. The ASLVs had a five-stage solid propellant system with a strap-on stage, consisting of two identical one-metre-diameter solid propellant motors similar to the SLV-3 series.

The ASLV's first two developmental flights in March 1987 and July 1988 were failures, with the first one not getting ignited at the first stage, after the strap-on stage burnt out.

The ISRO then decided to operationalise the PSLV series and obtained sanction from the Union government to go in for three more launches and christened them 'PSLV continued series'. Several improvements were incorporated, including the increase in the payload to 1,200 kg.

The PSLV-C1 had an increased solid propellant in the first core stage, the world's biggest first stage, with the weight increased to 138 tonnes from 128 tonnes. The second stage liquid propellant loading was also increased to 40.6 tonnes from 37.5 tonnes by stretching the stage tankages. A weight reduction was also effected in the vehicle equipment bay.

The PSLV development had involved path-breaking advances in solid motors, liquid propulsion stages, materials and fabrication technology, and inertial navigation and ground systems.

Two more PSLV continuation flights have been planned for the next two years. The next PSLV flight is likely to carry a Korean satellite riding piggyback on India's IRPS-P4 satellite.

ISRO has also taken up the Geosynchronous Satellite Launch Vehicle programme to place satellites in geostationary orbit. These vehicles, using cryogenic engines in the top stage, would take off from next year when the first developmental test flight, using a cryogenic stage supplied by Russians, would be launched.

The GSLV has the ability to place 2,500-kg INSAT-class satellites in geostationary transfer orbit. It would be a three-stage vehicle with the core being a 129-tonne solid booster as in the PSLV.

The triumph of the PSLV-C1's first flight has proved the country's capability to launch one-tonne class satellites in middle earth orbit.

UNI

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