T.S. Subramanian

Spacecraft was meticulously manoeuvred

The spacecraft is now circling the Moon over its polar regions

A fantastic achievement, says Madhavan Nair

CHENNAI: Chandrayaan-1 has kept its rendezvous with the Moon. In a meticulously planned operation, the Indian Space Research Organisation (ISRO) on Saturday accomplished the most crucial and critical manoeuvre of safely inserting Chandrayaan-1 into the lunar orbit.

This is the first time that an Indian-built spacecraft has broken away from the Earth’s gravitational field and reached the Moon. The spacecraft is now circling the Moon over its polar regions with a periselene (nearest point from the moon’s surface) of 504 km and an aposelene (farthest point) of 7,502 km.

The ISRO flawlessly executed this highly complex manoeuvre by radioing commands from the Spacecraft Control Centre (SCC), Bangalore, to the engine on board Chandrayaan-1, which fired for 817 seconds from 4.51 p.m.

ISRO Chairman G. Madhavan Nair called it “a fantastic achievement” and “a great moment for the country.” He described the manoeuvre as “the most crucial moment in the whole mission … We have done it so precisely that as far as I know nobody else has got this kind of precision… Our precision proves that in competence, our scientists and technologists are quite ahead of the global standards. With this, we have achieved more than 90 per cent of the main objectives of the mission.”

M. Annadurai, Project Director, Chandrayaan-1, said: “Today we graduated into a real lunar mission. Everybody is thrilled. This is the first significant milestone in putting Chandrayaan-1 into the lunar orbit.”

Mr. Annadurai said there were more steps to perform in the mission: progressively reducing Chandrayaan-1’s orbit to the final circular orbit of 100 km above the moon on November 15. “The first indications from the spacecraft show that everything has gone on the dot.”

The historic event took place after Chandrayaan-1 reached the vicinity of the Moon and commands were radioed to it for reducing its velocity by rotating the spacecraft in the opposite direction. In space parlance, it is called retro-firing. When Chandrayaan-1’s velocity was reduced by 366.8 metres a second, it was captured by the Moon’s gravity and safely ensconced in the lunar orbit.

S.K. Shivakumar, Director, ISRO Telemetry, Tracking and Command Network, Bangalore, where the SCC, the nerve-centre of the operations is located, called it “a wonderful feeling.”

Commands were being given to Chandrayaan-1 from the 32-metre and 18-metre antennas, and “their tracking of the spacecraft is excellent.” The signals received from the spacecraft were good too, Mr. Shivakumar said.

S. Ramakrishnan, Director (Projects), Vikram Sarabhai Space Centre, Thiruvananthapuram, applauded “the precision with which Chandrayaan-1 was inserted into the lunar orbit.” Had the slightest mistake been made, Chandrayaan-1 “would have skipped and gone away.”

  • Full text of ISRO press release
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