T.S. Subramanian

Chandrayaan-1 will be married up with PSLV on October 12 or 13

Launch likely on October 19 or 20

CHENNAI: Work in different centres of the Indian Space Research Organisation (ISRO) is gathering speed for the launch of Chandrayaan-1 at 6.20 a.m. on October 22 from India’s spaceport at Sriharikota.

The tall and elegant Polar Satellite Launch Vehicle (PSLV-C11) that will put Chandrayaan-1 in orbit is fully integrated at Sriharikota’s second launch pad. After having sailed through thermal and vacuum tests which simulated the conditions in deep space, Chandrayaan-1 is coursing through the final stages of vibration tests at the ISRO Satellite Centre (ISAC) in Bangalore to determine the integrity of its systems.

At Byalalu village, 40 km from Bangalore, two massive dish antennae, one with a 32-metre diameter and the other with a diameter of 18 metres, are ready to track Chandrayaan-1 during its 3.84-lakh km. odyssey to the moon, send commands and receive information on its health.

Chandrayaan-1 will carry 11 instruments – five from India and six from other countries – to study the minerals and chemistry on the moon’s surface from an altitude of 100 km above. “The vehicle is totally ready,” declared George Koshy, Mission Director. “Some tests are going on. Everything is in good shape.”

Mr. Koshy said Chandrayaan-1 would be married up with the PSLV on October 12 or 13 after the spacecraft arrived at Sriharikota from Bangalore in the first week of October. “We would like to launch on October 22. But a date before October 22… October 19th or 20th is my target.” The PSLV-C11 is fully integrated in the 83-metre tall (the height of a 26-storey building) Vehicle Assembly Building (VAB) of the second launch pad. It stands majestically on a huge mobile pedestal, with platforms surrounding the four stages of the rocket. The PSLV-C11, which weighs 316 tonnes and is 44.4 metres tall, will be wheeled very slowly on its pedestal from the VAB to the launch pad some days before the launch.

The mood is equally upbeat at the ISAC. “Vibration tests of the spacecraft are going on at the shake-table,” M. Annadurai, Project Director, Chandrayaan-1, said on Monday. “They started on October 25th evening. Things are under control.” The tests involved 120 accelerometers.

Mr. Annadurai said:

“It is not just putting the spacecraft on the table and vibrating it. We have to ensure that all accelerometers’ results are within limits.

“When the vibration is taking place, accelerometers will provide information on what is the response from each one of the instruments from the spacecraft. We will keep Chandrayaan in different orientations on the shake-table and test it. The vibration tests will ensure the integrity of the spacecraft.”

Now Chandrayaan-1 will be subjected to high levels of noise, simulating what happens when the rocket climbs up with the spacecraft.

Both the 32-metre and 18-metre dish antennae would be used, said S.K. Shivakumar, Director, ISRO Telemetry, Tracking and Command Network, Bangalore. “It is good to have two antennae.” The Control Centre, which will be the nerve centre of the Chandrayaan mission, was ready, he said. “Everything is focussed.”