India will soon design and develop its heaviest communications satellite GSAT-11 to provide advanced telecom services from 2011-12, a senior official of the Indian Space Research Organisation (ISRO) said here Friday. At 4.5 tonnes, it will weigh more than twice as much as the biggest Indian satellite in orbit now.

"Activities to design and develop GSAT-11 will start immediately, as the project has been cleared by the government at a cost of Rs.5-billion (Rs.500 crore)," ISRO Director S. Satish said.

The advanced communications technology satellite will be launched in mid-2011 on board the Geo-Synchronus Satellite Launch Vehicle (GSLV-Mark III) from ISRO's spaceport at Sriharikota, about 80 km north-east of Chennai.

"The satellite will be designed at our satellite centre in Bangalore, payloads consisting of 40 transponders in Ku/Ka band will be built at the space applications centre in Ahmedabad and the 630-tonne rocket (GSLV-Mark III) will be rolled out from the liquid propulsion systems centre in Thiruvananthapuram," Satish told IANS.

The indigenously developed GSAT series of satellites are aimed at revolutionising communications, spanning digital audio, data and video broadcasting. The earlier versions of GSAT such as GSAT-1 and GSAT-2 were designed with two S-band and three C-band transponders.

"With 16 high capacity multi-beams in Ku/Ka band, GSAT-11 will provide much faster uplinks for a host of communications and broadcasting services, including direct-to-home (DTH television). With a dry mass of 2.1 tonne, the spacecraft will provide 10 GHz of bandwidth, which will be equivalent to about 220 transponders of 36 MHz," Satish pointed out.

The advanced satellite will employ a new 1-4K Bus (computer network). It will be configured with two-sided large solar array panels generating 11 KW of power.

In the run-up to GSAT-11, the space agency is scheduling the launch of other communications satellites in the GSAT series over the next two years.

"The two-tonne GSAT-4, slated for launch by this year on board GSLV-Mark II, will have a communication payload comprising multi-beam Ka-band pipe and regenerative transponder and navigation payload in C, L1 and L5 bands," Satish said.

GSAT-4 will also carry a scientific payload, Tauvex, consisting of three ultra violet (UV) band telescopes developed by Tel Aviv University and Israel space agency for surveying a large part of the sky in the 1,400-3,200 �ngstrom wavelengths.

Propulsion with four stationary plasma thrusters, Bus Management Unit (BMU), miniaturised dynamically tuned gyros, 36 AH Lithium ion battery, 70 V bus for Ka-band and on board structural dynamic vibration beam accelerometer are some of the new technologies developed for GSAT-4.

"GSAT-4 spacecraft will a power generation capability of 2,500 watts and will be positioned at 82 degrees east longitude in a geo-stationary orbit, about 36,000 km above the earth," the official said.

GSAT-1 was launched on board a technology demonstrator (GSLV-D1) April 18, 2001 as an experimental satellite for performance monitoring, tracking, range safety/flight safety and preliminary orbit determination.

GSAT-2 was launched May 8, 2003 and is located at 48 degrees east Longitude and carries four C-band transponders and two Ku-band transponders.

"The dedicated satellite for distance education (Edusat), launched in September 2004, is part of the GSAT series and can be considered as GSAT-3. Its transponders and their ground coverage are specially configured to cater to educational requirements," Satish added.

The remaining spacecraft in GSAT series such as GSAT-5, GSAT-6 and GSAT-8 will be equated with INSAT-4 series of communication satellites. In the series, the government has not yet approved the development of GSAT-7 and GSAT-10 satellites.

GSAT-5 or INSAT-4D will be configured as an exclusive C-band communication satellite. It will carry 12 normal C-band transponders and six extended C-band transponders with wider coverage in uplink and downlink over Asia, Africa and Eastern Europe as well as zonal coverage.

GSAT-5 will be launched on board GSLV in 2010 and positioned at 82 degrees east longitude.

The two-tonne GSAT-6/INSAT-4E will have a multimedia mobile S-band transponder to provide entertainment and information services to consumers and vehicles through digital multimedia consoles and multimedia mobile phones. It is also slated for launch next year and will have a mission life of 12 years.

GSAT-8/INSAT-4G is proposed as a Ku-band satellite with 24 transponders similar to that of INSAT-4A and INSAT-4B.

"It will also carry the second GPS aided Geo Augmented Navigation (GAGAN) payload," Satish told IANS. "The satellite is expected to be launched in the second half of 2010 and will be positioned at 55 degrees east longitude."