Chandrayaan-1 In The Moon's Orbit

Isro’s mission controllers on Saturday evening plucked the lunar spacecraft Chandrayaan-1 out of earth’s gravitational influence and safely inserted it into an orbit around the moon.

Isro executed the maneuver by sending a command to the spacecraft at 4.51 pm from its nerve center in Peenya, Bengaluru, to fire its engine for precisely 817 seconds. Isro chairman Madhavan Nair said the operation was the "most critical part" of the mission. "We have done it," he exulted. "For the last 20 minutes almost all our hearts were at a standstill," he said.

"The reason the lunar orbit insertion is risky is that we do not get an extended time window to conduct the operation. It had to be done when the spacecraft was exactly 500 km from the moon," Isro spokesperson S. Satish told this newspaper. "At the precise moment that the spacecraft goes out of the influence of earth’s gravity, it must also be captured by the moon’s gravity. Otherwise the spacecraft will be lost in deep space," he explained.

In the past, this earth-to-moon hand-off has proved to be the death knell of several spacecraft which either missed the moon to be lost in deep space, or crashed onto the lunar surface,

Chandrayaan-1 is now in an elliptical orbit that passes over the moon’s polar regions. Its nearest point to the moon (periselene) is 504 km and farthest (aposelene) 7,502 km. In about four further maneuvers, Isro will lower the spacecraft into a circular orbit 100 km above the moon.

The first instrument on the spacecraft has been switched on. The honor went to the Bulgarian instrument Radom which is gathering radiation intensity data.

The Moon Impact Probe piggybacking on Chandrayaan-1, with the Indian tricolor embossed on it, will hard-land on the moon by November 14-15. Isro will then test and switch on one instrument every day.