T.S. Subramanian

ISRO scores another success; two more manoeuvres remain

CHENNAI: The Indian Space Research Organisation (ISRO) executed without blemish on Monday night “an important manoeuvre.” It steeply reduced Chandrayaan-1’s aposelene (the farthest distance from the moon) and took the spacecraft closer to the Moon. This was accomplished by ISRO giving commands to the engine on board the spacecraft to fire and reduce its velocity. The engine fired for 866 seconds from 9.58 p.m. This led to Chandrayaan-1’s aposelene being reduced from 7,502 km to 255 km and its periselene (nearest distance to the Moon) from 200 km to 187 km.

M. Annadurai, Project Director, Chandrayaan-1, said, “Everything went off nicely” when the engine began firing and “the manoeuvre went off well.”

In the latest orbit in which Chandrayaan-1 is circling the moon, it takes two hours and 16 minutes to go round the Moon once.

Two more manoeuvres remain to be executed to bring the spacecraft to its final circular orbital home of 100 km above the Moon’s surface, Mr. Annadurai said.

The first of these manoeuvres would take place on Tuesday night and it would reduce the spacecraft’s aposelene from 255 km to 100 km. The second manoeuvre, which would be done on Wednesday night, would reduce its periselene from 187 km to 100 km. Thus, on Wednesday, Chandrayaan-1 would be ensconced in its final orbit.

Orbit to be studied

“We will study Chandrayaan-1’s final orbit of 100 km by 100 km above the moon for a day or two. We will then release the Moon Impact Probe,” Mr. Annadurai said.

All sub-systems on board are functioning satisfactorily.

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