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GSAT-1 was an experimental satellite launched aboard the GSLV-D1 (Technology demonstrator) for performance monitoring, tracking, range safety/ flight safety and preliminary Orbit Determination (POD). The vehicle is provided with instrumentation using Pulse Code Modulation (PCM) transmitting in S-band frequency and transponders operating in C-band.
GSAT-1 has encountered minor problems, preventing plans of carrying out experiments on board. The 1.54-tonne satellite was orbiting with a period of 23 hours two minutes, instead of the planned 24-hour geosynchronous orbit. The satellite was to be used for a variety of experiments such as digital audio broadcasting and compressed digital TV signal transmission.
The GSLV (Geosynchronous Satellite Launch Vehicle) suffered a performance shortfall during its first flight resulting in the injection of the experimental satellite into a geosynchronous transfer orbit (GTO) of 181 x 32.051 km, inclined at 19.2 degrees, having an apogee about 4,000 km below the targeted orbit of 185 x 35.975 km. The satellite used its onboard propulsion system to raise both its apogee and its perigee to geostationary orbit as well as to decrease the orbital inclination to zero, however its propellant was depleted prior to successfully raising its orbit. The satellite used two different propellant tanks, built in Germany and India, which resulted in an unequal flow of fuel, causing the spacecraft to tilt. (The two different fuel tanks were used because they were readily available). Recovery required the use of more propellant than planned which resulted in the satellite having no propellant left to complete its final circularization maneuver. The satellite was possibly used for a few communications experiments but the original purpose of demonstrating digital TV and audio broadcasts, as well as Internet services could not be fulfilled.
The Russian 12KRB cryogenic upper stage was planned to perform for 710 seconds, but its burn apparently lasted only 698 seconds. Another suspect for the shortfall is the launch vehicle navigation system which was derived from the PSLV which has flown only to low earth orbits.
See also