Indian Space Research Organisation GSAT 1

Indian Space Research Organisation GSAT 1

Indian Space Research Organisation (ISRO) launched the first developmental test flight of India, called GSLV, on 18^th April, 2001 from SHAR Centre, Sriharikota. The GSLV (Geosynchronous Satellite Launch Vehicle) carried with itself the communications satellite GSAT 1 which was successfully introduced in the orbit with perigee of 181 kilometers and apogee of 32,051 kilometers.  The angle of inclination of the satellite was at 19.2 degrees with the equator. The deployment of the satellite into the orbit happened initially at about 5000 kilometers from the site of launch from the earth.

The launch programme was not, however, without initial and final hitches. The launch was scheduled for 28^th March, 2001 but could not be carried out because one of the strap-on boosters did not develop the sufficient thrust. The flaw was rectified and the vehicle was readied for re-launch in less than a month. The satellite was equipped with three C-band and one S-band transponders meant for carrying out communication experiments like digital audio broadcast, internet services and compressed digital TV transmission.

Unfortunately, these purposes could not be achieved as the effort to raise the perigee and apogee as well as to decrease the orbital inclination to zero proved futile due to depletion of propellant. Moreover, the two fuel tanks built in Germany and India that were readily available at the time of launch were not exactly identical resulting in the unfavorable tilt of the satellite. Final circularization manoeuvres could not be successful the Russian 12KRB cryogenic upper stage lasted 698 seconds as against the originally planned 710 seconds.  One more factor which was suspected for the failure was the launch vehicle navigation system suitable for PSLVs used for low earth orbit missions.

Though the GSAT 1 could not be a total success, the experience gained from the launch was highly useful for several forthcoming successful GSLV missions.