The integration process of the spacecraft structure and antennae has begun for Chandrayaan-1, the country's first unmanned moon mission which is scheduled for March 2008, Indian Space Research Organisation said on Wednesday.

The spacecraft structure for the mission has arrived at the ISRO satellite centre from Hindustan Aeronauticals Limited and integration work has begun, S Krishnamurthy, director, Publications and Public Relations, told PTI from Bangalore.

ISRO's Deep Space Tracking Network system, which is being established for the moon mission at Byalalu village, 40 km from Bangalore, has already erected its first 18-mt antenna, he said.

The prestigious 32-mt antenna built by the Electronic Corporation of India and Bhabha Atomic Research Centre is currently being erected at DSTNS, Krishnamurthy said.

Krishnamurthy added that the instruments from various collaborators, including European Space Agency and NASA, have started coming in.

The Chandrayaan-1 mission, that involves placing of a 525-kg spacecraft around the lunar orbit, is expected to provide impetus to science in India by unravelling some of the unknown features of the moon.

According to ISRO, it is also a challenge to technology, and possibly adds a new dimension to both Indian and international cooperation.

ISRO also has an agenda for the preparation of the three-dimensional atlas of the regions on the moon and the chemical mapping of the entire lunar surface.

According to M Annadurai, director-in-charge of the Chandrayaan-1 mission, the launch schedule is targeted early next year.

"But technically we have three to four launch dates targeted," he said in an e-mail communication recently.

"This is because, a mission like Chandrayaan-1 needs few launch opportunities. I am aiming for a launch not later than March end or early April 2008. Currently we are on schedule, with 30 days of schedule margin, leading to March 2008 launch," Annadurai added.

"All systems and instruments are getting ready for flight integration. Accordingly, our target schedule for launch is as follows: 1) February 29, 2008 (If there is no slip in the current integration schedule); 2) March 13 (assuming 15-day slip); 3) March 26 (assuming 30-day slip); 4) April 9 (one more backup date)," he said.

"You may note unlike other satellite launches, it is difficult to have daily launch opportunity for Chandrayaan-1, as we need a particular moon geometry from earth to have optimal mission mode. So, we prefer not to miss the above launch opportunities," he said.

"ISRO is fully geared up to meet this challenge," he said.