Antenna for tracking Chandrayaan

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A view of the antenna meant to track the proposed Chandrayaan, put up at Byalala Village, 40 km southwest of Bangalore.
A view of the antenna meant to track the proposed Chandrayaan, put up at Byalala Village, 40 km southwest of Bangalore.

T.S. Subramanian

To send commands, receive data and track the ISRO's spacecraft to the moon

  • The 18-metre antenna is in position and its erection completed
  • ISTRAC engineers looking forward to installing the antenna with a 32-metre diameter

    CHENNAI: A massive dish-shaped antenna with a diameter of 18 metres has been erected near Byalalu village, about 40 km from Bangalore, to send commands, receive data and track ISRO's Chandrayaan-I spacecraft to the moon.

    The device forms part of the Indian Space Research Organisation's ambitious plans to establish a Deep Space Network (DSN) of big antennae that will track not only ISRO's Chandrayaan-I and Chandrayan-II spacecraft to the moon but also its mission to Mars.

    Spacecraft missions

    G. Madhavan Nair, ISRO Chairman, said: "First of all, the Deep Space Network is going to be a national effort. It is going to serve not only the moon mission, but other spacecraft missions at a later date, such as one to Mars."

    ISRO's more powerful Polar Satellite Launch Vehicle called PSLV-XL will speed into the sky from Sriharikota in the first quarter of 2008 to put Chandrayaan-I spacecraft in orbit about 100 km above the moon's surface.

    As part of the DSN programme, installation of another huge antenna with a diameter of 32 metres is all set to begin at Byalalu this month.

    Pedestal complete

    Construction of a pedestal, which is a civil structure necessary to support this 32-metre antenna, is almost complete at the site.

    The 32-metre antenna will keep a tab on the Chandrayaan-II spacecraft and ISRO's inter-planetary probes. A DSN is essential for these missions because of the huge distances involved. For instance, the moon is about 3.86 lakh km away from the earth.

    Tracking spacecraft

    Mars is six crores km away when it is nearest to the earth. As spacecraft travel towards the moon or Mars, they have to be constantly tracked, commands sent to them and data received from them.

    "Today, the 18-metre antenna is in position. We have completed its erection. We are conducting tests and evaluation. It is working all right," said S.K. Shivakumar, Director, ISRO Telemetry, Tracking and Command Network (ISTRAC), Bangalore. ISTRAC is responsible for establishing the DSN at Byalalu.

    The installation of the 18-metre antenna was a turn-key job. It was built by the Vertex RSI, a Germany company, to ISRO's specifications.

    Three parts

    According to G.R. Hathwar, general manager, Technical Services Group, ISTRAC, the entire 18-metre contraption can be divided into three parts.

    They are: the bowl/the dish with reflector panels made of aluminium; the mount that allows the antenna to move horizontally and vertically to track any object in space; and the pedestal, that is the building, on which the mount is erected. The height of the entire column from the ground is 25 metres.

    But what the ISTRAC engineers are looking forward to is the installation of the antenna with a 32-metre diameter.

    Indigenous effort

    "The design, development, fabrication and installation of the 32-metre antenna will be a totally indigenous effort. This is the first of its kind in the country and it is technologically challenging in fabrication. It involves all elements of engineering," said Mr. Shivakumar.


    The Electronics Corporation of India Limited (ECIL), a unit of the Department of Atomic Energy, is the prime contractor for executing the 32-metre antenna project.

    The project will be national effort, with key contributions from the ECIL, Bhabha Atomic Research Cente (BARC), ISTRAC, ISRO Space Applications Centre and industries. By June 2007, the antenna will be in position and start operating.

    Selection of Byalalu village to locate the antenna was a major exercise. Thirteen teams fanned out several hundred kms from Bangalore and examined about 40 sites. Byalalu with Savanadurga hills at a distance was chosen.

    Noise survey

    "We did a thorough noise survey and a blockage study. We assured ourselves that there was no natural terrain blocking our view. When I point my antenna towards the target, there should also be no tall building blocking the signals," said Mr. Shivakumar.

    The noise survey showed that there were no major frequencies there.

    Another antenna

    ISTRAC will soon start building at Byalalu another antenna with a diameter of 11 metres for ISRO's ASTROSAT mission, which will be an observatory in space for astronomical studies.

    When the DSN is complete with three antennae of 18, 32 and 11 metres diameter, "nobody in this part of the world will have a ground station of this magnitude and size," said Mr. Shivakumar.

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