32-metre dish antenna installed for Chandrayaan-I

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MOON MISSION: The installation of the 32-metre dish antenna to track Chandrayaan-1 has been completed at Bylala village, near Bangalore.
MOON MISSION: The installation of the 32-metre dish antenna to track Chandrayaan-1 has been completed at Bylala village, near Bangalore.

T.S. Subramanian

ISRO plan to send spacecraft to moon gathers speed

CHENNAI: The Indian Space Research Organisation’s ambitious plan to send the spacecraft Chandrayaan-I to the moon has gathered speed with the installation of a huge dish antenna at Byalalu village, 40 km from Bangalore. The dish is 32 metres in diameter and weighs 60 tonnes.

All its petals have been assembled at a height of more than 27 metres from the ground.

The antenna will send commands to Chandrayaan-I to perform various manoeuvres during its 3.84 lakh-km journey to the moon.

The antenna will receive information from Chandrayaan-I about the health of its cameras and payloads, and science data about the moon.

This antenna is the centrepiece of a Deep Space Network (DSN) coming up at Byalalu. A muscled version of the ISRO’s Polar Satellite Launch Vehicle will lift off with Chandrayaan-I from Sriharikota on April 9, 2008.

“The installation of the 32-metre dish antenna has been completed in all aspects. It is an all-out Indian effort.

It gives us a sense of fulfilment. It is a dream project for radio frequency engineers,” S.K. Shivakumar, Director, ISRO Telemetry, Tracking and Command Network (ISTRAC), Bangalore, said on Saturday. The ISTRAC is responsible for establishing the DSN at Byalalu.

The integration of the dish antenna with motors and gearboxes called servo control system, located separately in a room, is under way. These motors and gearboxes will move the antenna to track various spacecraft.

The antenna will track Chandrayaan-I, Chandrayaan-II and the ISRO’s proposed spacecraft to the Mars. Chandrayaan-II will land a rover on the moon.

Mr. Shivakumar is especially happy that the installation of the dish along with the beam wave guide system (BWGS) has been completed. “It is one of the critical challenges we have met.”

With seven mirrors, it is a crucial system that communicates with Chandrayaan-I by sending commands to it and receiving signals including scientific information about the moon.

N. Ramakrishna Reddy, ISTRAAC engineer and core designer of the BWGS, said it was totally indigenously designed and developed.

The antenna is a massive system with the dish, mount, bull gear systems and wheels. The total antenna system weighs 350 tonnes. It is 11-storey (32 metres) tall from the ground to the tip of a quarter-pod installed inside the dish which is also called the reflector.

The dish can rotate horizontally and vertically from zero to 90 degrees.

Circular track

The antenna rotates on a circular track on four wheels, called the wheel and track system.

“All four wheels are aligned with extreme precision,” said Reddy.

They move very slowly. Each wheel weighs two tonnes and is 20 cm thick. The bull gear is the rotating system which supports the dish.

The dish was designed and developed by the Electronics Corporation of India Limited (ECIL), Hyderabad.

Others who made important contributions to the project included the ISTRAC, the ISRO Satellite Centre (ISAC), Bangalore, L and T, Godrej, Vamshi Electronics, Hyderabad, and SLN Technologies Private Limited, Bangalore.

At the ISAC, the integration of various payloads of Chandrayaan-I gathered momentum, said M. Annadurai, Project Director.

It would carry 11 instruments – five from India and six from abroad. Four instruments from abroad were already integrated.

In December, the Indian payloads would undergo assembly integration testing and in January 2008, two payloads from abroad.

Simultaneously, Mr. Annadurai said, the spacecraft would be subjected to tests simulating the various manoeuvres it would perform as it travelled to the moon.



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