The Hindu : Front Page : Chandrayaan-1 orbit raised

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Sunday, Oct 26, 2008
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Chandrayaan-1 orbit raised

T.S. Subramanian

It goes past the 36,000 km high geo-synchronous orbit for first time

CHENNAI: The Spacecraft Control Centre (SCC), Bangalore, the nerve-centre of the Chandrayaan-1 mission now, echoed with cheers around 5.45 a.m. on Saturday when the radio commands sent from there to the spacecraft went home and the propulsion system on board started firing furiously. The firing lasted 16 minutes. This led to the second successful raising of Chandrayaan-1’s orbit to an apogee of 74,715 km. and a perigee of 336 km. in its journey in deep space to the moon, which is 3.84 lakh km. away. This is the first time that an Indian spacecraft has gone beyond the 36,000 km high geo-synchronous orbit and reached an altitude twice that height. (Geo-synchronous satellites are positioned at an altitude of 36,000 km from the earth).

The first manoeuvre on Thursday was also successful, increasing Chandrayaan-1’s orbit to an apogee of 37,900 km. and a perigee of 305 km. from its initial orbit of 22,866 km. by 256 km. The Indian Space Research Organisation’s (ISRO) Polar Satellite Launch Vehicle (PSLV-C11) had on October 22 catapulted Chandrayaan-1 into its initial orbit with an apogee of 22,866 km and a perigee of 256 km.

M. Annadurai, Project Director, said on Saturday from Bangalore, “The manoeuvres went through early in the morning. Everything is normal. Things are under control.” He said the third manoeuvre to further raise the spacecraft’s orbit would take place on Sunday morning.

After the successful launch of the spacecraft, Mr. Annadurai had cautiously said, “This is our first step. The spacecraft has just been delivered into its initial orbit. We have to go a long way in time and distance in this mission before Chandrayaan-1 reaches its final lunar orbit at an altitude of 100 km above the moon’s surface.”

If things go on schedule, Chandrayaan-1 will reach this lunar orbit on November 15/16. The commands for firing the propulsion system are sent from the SCC located at the ISRO Telemetry, Tracking and Command Centre (ISTRAAC), Bangalore through two bowl-shaped antennae set up at Byalalu village, about 40 km away. While the huge antenna with a diameter of 32 metres is an “all-out Indian effort,” the 18-metre dish-shaped antenna has been imported from Germany.

The dish of the Indian antenna, made of “petals,” weighs 60 tonnes.

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