T.S. Subramanian

India’s first moon mission to take off at 6.22 a.m. on Wednesday

Countdown reduced from 52 hours to 49 hours

Lightning and electric charges in clouds are causes for concern

CHENNAI: The final 49-hour countdown for the lift-off of India’s Polar Satellite Launch Vehicle (PSLV-C11), which will put Chandrayaan-1 into orbit, began around 5.30 a.m. on Monday at the spaceport at Sriharikota in Andhra Pradesh.

The launch is scheduled to take place at 6.22 a.m. on October 22 (Wednesday).

“The countdown is going on smoothly,” said M.Y.S. Prasad, Associate Director, Satish Dhawan Space Centre, Sriharikota, on Monday evening. “The countdown involves a lot of activities and continuous operations, in which hundreds of people work simultaneously. These activities and operations will by synchronised and linked to the common time,” Dr. Prasad explained.

The Indian Space Research Organisation (ISRO), which had earlier decided on a 52-hour countdown, later preferred a 49-hour countdown because “our countdown activities are always optimised,” added Dr. Prasad.

However, dark clouds gathered over the island on Monday and there were spells of rain. “The vehicle is rain-proof, and unless there is a real problem on the weather front, the lift-off will take place on Wednesday. What we are worried about is lightning and electric charges in the clouds,” an ISRO official said.

This is the first time that ISRO is sending a spacecraft to the moon, 3.84 lakh km from the earth. It is a complex mission because ISRO has to continuously communicate with the spacecraft as it journeys this huge distance through deep space, give commands to perform various tricky manoeuvres and ultimately lower Chandrayaan-1 into the lunar orbit at an altitude of 100 km and “stick” to this orbit.

Two huge dish antennas, one with a diameter of 32 metres and another of 18 metres, have been installed at Byalalu village, about 40 km from Bangalore, to radio commands to Chandrayaan-1 and receive information about its health. The antennas will also receive information on the scientific data that will flow from the 11 instruments on board the spacecraft.

The 32-metre dish antenna is a totally indigenous effort, made possible by the Department of Atomic Energy (DAE) and ISRO units and private industries. S. Satish, Director, Publications and Public Relations, ISRO, called it an engineering marvel. The dish antenna alone weighs 60 tonnes. Its “petals” had to be assembled with an accuracy of a few millimetres at a height of more than 27 metres from the ground. The 18-metre dish antenna is a turn-key job done by Germans.

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