PTI

Bangalore, Jul 17: The star sensor failure on board Chandrayaan-1 would not curtail the two-year moon odyssey and more than 90 per cent of the mission's scientific objectives had already been achieved, ISRO said on Friday.

The space scientists were able to recover within a week from the May 16 "anomaly" (star sensor failure) and put the spacecraft back into normal operation, Indian Space Research Organisation Chairman G Madhavan Nair told reporters here.

He said the star sensor, one of the prime sensors, was used for determining the spacecraft's altitude. Looking at the stars, this sensor can determine the orientation of the moon spacecraft accurately.

ISRO is now using gyroscopes, electro-mechanical devices used for Indian Remote Sensing class of satellites, which gives the orientation accuracy quite satisfactorily, he said.

Nair said more than 90 per cent of the scientific and mission objectives had already been achieved, and dismissed suggestions that the sensor failure might reduce the lifespan of the spacecraft.

"Life (of the spacecraft) is not dependent on this instrument. This instrument is used only for orientation of the spacecraft," he said. "The sensor cannot be recovered at this stage and we hope that the remaining part of this mission will be completed in the gyromode as expected".

Nair said ISRO had a meeting a month ago with the Indian scientific community, which stated that about 90 per cent to 95 per cent of the scientific objectives of the mission had been completed.

"We are happy that almost all the mission objectives which have been set for this (mission) has been achieved," he said.

"More than 90 per cent of the mission objectives have been completed as on date, and the pending activities are related to collecting more images of the Moon, both for terrain mapping as well as the mineral mapping. These operations also, we plan to complete soon. So, with that we will be completing the entire operation relating to Chandrayaan-1 in a successful manner," he said.

The ISRO Chairman said the star sensor would have "gone into problem" because of "excessive radiation" from the Sun.

Asked how long gyroscopes, which have been activated, would survive, Nair said: "...we know electro-mechanic gyros which have been used...they are not susceptible for this kind of radiation and other parameters. So, we hope it will survive the remaining mission duration."