Chandrayaan-1 Enters the Operational Lunar Orbit
Thursday, 13th November, 2008
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Milestone ISRO scientists achieved another milestone on Wednesday when they successfully entered
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Orbit-Insertion Earlier, Chandrayaan-1, which was launched from Sriharikota on October 22, was successfully entered into lunar orbit Saturday, October 9. Lunar orbit insertion of Chandrayaan-1 was the most challenging task because gravity of moon and that of earth cancel each other out at that stage. Spacecraft’s liquid engine was fired for 817 seconds and then its speed was reduced to 366 metres per second when is flew into the moon’s orbit. At that stage nearest point of orbit from the moon’s surface was at the distance of 504km while the farthest point was 7,502 km. At that orbit it was taking 11 hours to go around the moon.
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Orbit Reduction On October 10 scientist had reduced its periselene (nearest point from the moon) to 200 km while aposelene continues at 7,502 km. To put Chandrayaan-1 into this orbit engines were fired for almost one minute. In their next major step ISRO scientists had fired Chandrayaan-1 engine for 866 seconds to reduce its aposelene from 7,502 km to 255 km and its periselene (nearest distance to the Moon) from 200 km to 187 km. At that orbit Chandrayaan-1 was taking 2 hours and 16 minutes to go around the moon. On November 11 its periselene was reduced from 187 km to 101 km by firing the engines for 31 seconds. ISRO spokesperson has said that it will Moon Impact Probe, with the Indian flag painted on its sides, will crash-land on the moon on 14 or 15 November. And all the remaining 10 scientific instruments will be switched one after another.

