A giant step to space
The long stretch of road from Sullurpetta to Sriharikota looks like an endless one. As endless
as space? On both sides stretch vast expanse of land holding just enough water to paint the ground silver. At places, footprints of man or animal show across the wet sand. Right now, the Pulicat lake and sanctuary do not have many avian migratory visitors. The impending July launch of Insat 4 C does not seem to interest this species anyway.
Once upon a time an island with the lake on two sides and the ocean on the other, this is Sriharikota, the space port of the country now connected by a road built across the lake.
Located on the east coast of Andhra Pradesh and 80 kms from Chennai, the island covered with lush greenscape, was chosen as the ideal site for a satellite launch station back in 1969.
Nearness to the equator, advantage of earth’s rotation for eastward launching and large uninhabitated areas for safety were some of the criteria.
Starting way back in 1971 with flight test of Rohini, SHAR has today seen 20 launches. The last was that of PSLV-C6 in May 2005. Four satellites of other space agencies have so far been launched by India.
The next big event is slated for July 10 when the Insat 4 C will be placed in a geosynchronous orbit by the indigenously built GSLV. The launch vehicle is already assembled, the three stages - two liquid and one cryogenic - and the solid propellant strap-ons in place around the first stage. Housed in the vehicle assembly building, it now awaits its payload.
At the first launch pad, the PSLV is in the process of assembly, having time till September for launch when it will place at least three satellites in orbit.
Light and fire? No!
Rocket science is indeed rocket science. There is so much work to be done before standing back and watching a magnificent rocket take off to the skies. Production of individual parts, checking under various conditions, rechecking, assembling, checking again, and then the thundering, fiery launch.
Even then, there can be no relaxing till the satellite is placed in orbit and all its systems are working, beginning with the solar sails so vital for the energy requirements of the satellite. Communications lines are as crucial. For all this, the health of the computer on board is vital.
Crick in the neck
Usually, the individual parts of the launch vehicle are checked separately before being sent to the launch pad. Here a 76-metre tall mobile service tower (MST) inside the 83 m tall assembly building, aids the vertical integration of the various stages. Atop a launch pedestal made of steel, the launch vehicle begins to grow tall, day by day, part by part.
The first, second and third stages and finally on top comes the satellite payload. This is integrated on to the vehicle in a clean room (where there are only 1 lakh particles of 0.5 micron in a volume of 1 metre3, and that is being remarkably clean in the particle world!)
In the case of the GSLV the encapsulated satellite is brought to the launch pad after being prepared in facility elsewhere.
Finally, the vehicle is moved on the pedestal to the 70 m tall umbilical tower that houses the feed lines for the liquid and cryogenic propellants (liquid oxygen and hydrogen), high pressure gases, chilled air duct, etc required for the satellite’s health. The filling of the propellants are automated and remote controlled from a distance. There is a filling control centre with 17 consoles that handles this aspect alone. Similar checkout systems are present at the assembly building.
The MST leaves the vehicle on the pedestal and moves back. The vehicle stays on the pad for around 10 days when all the checks are done before launch. On launch, the umbilical wires are snapped cut, rather symbolically, as the bird leaves the nest.
The launch area has a concrete pad foundation to anchor the launch pedestal. Below is a jet deflector, an underground wedge type tunnel, that helps divert the hot exhaust gases away from the pad. The duct with refractory lining (that can withstand heat) extends on both sides to 80 m.