www.hindu.com/2009/08/30/...53760100.htm

ISRO loses radio contact with Chandrayaan-1

T.S. Subramanian

India’s first moon mission cut short; a lot of data gained

CHENNAI: In a major blow to India’s maiden mission to the moon, the Indian Space Research Organisation (ISRO) abruptly lost contact with Chandrayaan-1 at 01.30 a.m. on Saturday. This means no command can be given to the spacecraft and no data, including images of the moon’s surface, are being received from it.

The Chandrayaan-1 mission has come to an end in ten months instead of its slated life of two years.

“We are not able to give commands to the spacecraft,” S. Satish, Director, Publications and Public Relations Department of ISRO, told The Hindu. “We are not able to establish communication with it, with the result that we do not know what is happening.”

The Indian Deep Space Network (IDSN) at Byalalu village, near Bangalore, received data from Chandrayaan-1 till an hour before radio contact was lost. The IDSN, with its huge antennae with diameters of 32 metres and 18 metres, is the hub of communications from the ground with the spacecraft. It is from Byalalu that commands were radioed to the spacecraft to perform various manoeuvres. Images from Chandrayaan-1 were also received here.

India’s first spacecraft to the moon was launched on October 22, 2008 from Sriharikota. An ISRO press release noted on Saturday that the spacecraft had completed 312 days in orbit, making more than 3,400 orbits around the moon. It provided a large amount of data from its sophisticated instruments such as the Terrain Mapping Camera, the Hyper-Spectral Imager, the Moon Mineralogy Mapper and so on. ISRO claimed that the mission had met most of its scientific objectives.

Chandrayaan-1 sent back more than 70,000 images of the lunar surface, which provided breathtaking views of lunar mountains and craters, especially craters in the permanently shadowed areas of the moon’s polar region. It also collected data on the chemical and mineral content of the moon’s soil.

But the troubles that have cut short the life of the moon mission began in November itself when the spacecraft’s power subsystems started failing one by one. In April, the mission went into a crisis, with the primary star-sensor and the backup star-sensor failing. But top ISRO officials appeared keen to play down the setbacks, with a May 20 press release making no mention of the failure of the star-sensors and the power units.

Asked what could have gone wrong with the spacecraft, Mr. Satish said: “Some electronic sub-system could have malfunctioned. We are looking at the telemetry data and trying to find out what is the problem. Using the telemetry data [received till contact with the spacecraft was lost], the health of the spacecraft is being analysed. It is expected to throw light on the problem noticed. ISRO’s stations are trying to revive the spacecraft.”

Asked whether Chadrayaan-1 was drifting away from its orbit, Mr. Satish said it was “definitely in orbit.” However, if the present situation continued, the orbit could be disrupted.

ISRO experts explained that all communication with Chandrayaan-1 and the receipt of data from it were handled through on-board electronic systems. “If radio contact with Chandrayaan is suddenly lost,” a top expert pointed out, “only electronic systems on the spacecraft could have failed. Otherwise, this could not have happened. From the symptoms, it looks as if the electronics failed.”

A Polar Satellite Launch Vehicle (PSLV) of ISRO put Chandrayaan-1 in its initial orbit. The spacecraft carried 11 instruments on board. One of them named the Moon Impact Probe (MIP) “impacted” on the lunar surface on November 14, 2008, signalling India’s success in reaching the moon.