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.'