Scientists save India's moon mission from failure

[abdulrafi]

Scientists save India's moon mission from failure
By VIJAY JOSHI (AP) – 1 hour ago

NEW DELHI — India's only satellite orbiting the moon came close to overheating and failure but scientists improvised to save it, officials said Friday

The launch of Chandrayaan-1 last fall put India in an elite group to have lunar missions along with the U.S., Russia, the European Space Agency, Japan and China.

But last month the satellite lost a critical instrument called the star sensor, said S. Satish, the spokesman of the Indian Space Research Organization.

The sensor helps the $80 million satellite stay oriented so its cameras and other recording equipment are constantly aimed at the lunar surface. Without the sensor, the mission is useless, Satish said.

ISRO chief Madhavan Nair told the NDTV television network that the satellite came close to overheating and failing after it was put into orbit 60 miles (100 kilometers) from the moon.

"The entire spacecraft would have baked and would have been simply lost," Nair said. Many power systems and instruments failed.

The ISRO team then resorted to using other systems such as an antenna mechanism and gyroscope to make sure the satellite was "looking at the moon," Satish told The Associated Press in a telephone interview. The orbit was raised to 120 miles (200 kilometers).

"As a result, the mission is safe and all the systems are working," he said.

As India's economy has boomed, it has sought to convert its newfound wealth — built on the nation's high-tech sector — into political and military clout.

Scientists hope the Chandrayaan project will boost India's capacity to build more efficient rockets and satellites, especially through miniaturization, and open research avenues for young Indian scientists.

Chandrayaan, which means "moon craft" in Sanskrit, is scheduled to last two years.

"We hope we will be able to complete two years in this mode. It may or may not last that long," said Satish. "But there is no need for a major concern. We already have got substantial data from the moon," he said.

India plans to follow the mission by landing a rover on the moon in 2011.

 

[Arun tevar]

Brother,the star sensor even if failed can easily be accomodated with other alternatives with minor loss of accuracy as the other sensors have to depend on the signals and readings of the rotating moon.While the star sensor depends on a fixed celestical body for guiding & navigational requirements of the sat.

 

[abdulrafi]

Chandrayaan falters as ‘star sensors’ fail

Divya Gandhi

A handicap, but 90-95% of objectives accomplished: Madhavan Nair

G. Madhavan Nair.

Bangalore: Less than nine months after India’s first lunar satellite Chandrayaan-I was launched in the glare of media flash bulbs, the chairman of the Indian Space Research Organisation announced that the satellite’s ‘star sensors’ – vital in determining the orientation – had failed.

Describing the failure a “handicap,” Madhavan Nair told journalists at the ISRO headquarters on Friday, that Chandrayaan’s orientation had been set right by activating contingency “gyroscopes” on board.

Being an electro-mechanical device, however, the life-span of the gyroscopes cannot be predicted, said S. Satish, ISRO spokesperson. He added that on May 19 Chandrayaan’s orbit was raised from 100 km to 200 km from the lunar surface to “save fuel” after the gyroscopes were activated.

According to an ISRO press release, one of Chandrayaan’s bus management units, which performs crucial control functions on the spacecraft, has failed. This would imply that the spacecraft is running on the backup unit.

The technical snag, which occurred on April 26, was detected on May 16, according to ISRO sources. Mr. Nair attributed it to “excessive radiation from the sun” that “can degrade devices in the star sensors.” The sensors cannot be recovered at this stage and the remaining part of the two-year mission would be completed in the “gyro mode,” he said, adding that “the orientation accuracy has been quite satisfactory.”

Asked if the sensors’ failure would compromise the expected two-year life-span of the satellite, the ISRO chairman said: “The life [of the spacecraft] is not dependent on this instrument. This instrument is used only for orientation of the spacecraft.” A large number of other factors including fuel and telemetry would also contribute to a successful mission, he said.

He added that “90 to 95 per cent” of the objectives of the lunar mission had been accomplished, including reaching the satellite to a 3.84 lakh km orbit around the moon; capturing images of its terrain and ascertaining its mineral content; and placing the Indian tri-colour on its surface.

 

[PeacefulIndian]

Chandrayaan falters as ‘star sensors’ fail

According to an ISRO press release, one of Chandrayaan’s bus management units, which performs crucial control functions on the spacecraft, has failed. This would imply that the spacecraft is running on the backup unit.

I don't know why have you bolded & underlined this. Of course it is running on an alternate mechanism of gyroscope & antenna, which has been engaged due to failure of primary system , Star sensor. And it may reduce the life span of the craft, but Nair has already elaborated that he would not mind closing this mission out, if Chandrayan completes its objectives before its designated life span.

 

[abdulrafi]

Brother,the star sensor even if failed can easily be accomodated with other alternatives with minor loss of accuracy as the other sensors have to depend on the signals and readings of the rotating moon.While the star sensor depends on a fixed celestical body for guiding & navigational requirements of the sat.

it was in response to arun's posting