Chandrayaan-I enters lunar orbit

Eighteen days after it was fired into outer space, India’s maiden unmanned moon mission, Chandrayaan-I, today entered the tricky lunar orbit after scientists successfully carried out a most critical manoeuvre.

Space scientists at the Indian Space Research Organisation, or ISRO, carried out the lunar orbit insertion by firing the liquid engines on board the spacecraft for 817 seconds.

This is the first time that an Indian-built spacecraft has broken away from the Earth’s gravitational field and entered the moon’s.

“The lunar orbit insertion (LOI) began at 4:50 PM and lasted 817 seconds,” ISRO spokesperson S Satish told PTI. The satellite has been placed in a 7,502 km x 500 km elliptical orbit around the moon.

Heaving a sigh of relief, ISRO chief G Madhavan Nair said today’s operation was the “most critical moment” in the mission.

“We have done it,” a visbly happy Nair declared. Speaking from a ground centre near Bangalore, he added: “For the last 20 minutes, almost all our hearts were at a standstill.”

The spacecraft, launched on October 22, had been placed in the Lunar Transfer Trajectory on November 4.

Chandrayaan-I's liquid engine was fired when the spacecraft passed at a distance of about 500 km from the moon to reduce its velocity to enable lunar gravity to capture it into an orbit around the moon.

The spacecraft is now orbiting the moon in an elliptical orbit that passes over the polar regions of the moon. The nearest point of this orbit (periselene) lies at a distance of about 504 km from the moon's surface while the farthest point (aposelene) lies at about 7,502 km. Chandrayaan-I takes about 11 hours to go round the moon once in this orbit.

According to an ISRO press release, the performance of all the systems onboard Chandrayaan-I is normal.

The mission, orbiting the earth at a distance of 386,000 km, was commandeered from ISRO’s Telemetry, Tracking and Command Network (ISTRAC) at Peenya on the outskirts of the city, with the aid of the Indian Deep Space Network (IDSN) at Byalalu.

Chandrayaan-I would now be lowered gradually and placed in a circular orbit at a distance of 100 km from the lunar surface.