 GSAT-4 | |
| Mission type | Communication |
|---|---|
| Operator | ISRO |
| Mission duration | 7 years (planned) Failed to orbit |
| Spacecraft properties | |
| Bus | I-2K |
| Manufacturer | ISRO Satellite Centre Space Applications Centre |
| Launch mass | 2,220 kilograms (4,890 lb) |
| Power | 2,760 watts |
| Start of mission | |
| Launch date | 15 April 2010, 10:57 (2010-04-15UTC10:57Z) UTC |
| Rocket | GSLV Mk.II D3 |
| Launch site | Satish DhawanSLP |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Geostationary |
| Longitude | 82° East |
| Epoch | Planned |
| Transponders | |
| Band | Ka-band |
GSAT-4, also known asHealthSat, was an experimentalcommunication andnavigationsatellite launched in April 2010 by theIndian Space Research Organisation on the maiden flight of theGeosynchronous Satellite Launch Vehicle Mk.II rocket.[1] It failed to reach orbit after the rocket's third stage malfunctioned.[2] The third stage was the first Indian-builtcryogenic-fuelled upper stage, and was making its first flight. The ISRO suspects that the failure was caused by the third stage not igniting.[3]
Weighing around two tons, GSAT-4 carried a multi-channel,Ka-band,bent pipe and regenerativetransponder, and a navigation payload in the C, L1, and L5 bands. Designed to guide civil and military aircraft, GSAT-4 was to have employed several new technologies such as a bus management unit, miniaturised dynamically tuned gyros, lithium-ion battery, 70 volt bus for Ka-bandtravelling-wave tube amplifiers, and electric propulsion. GSAT-4 also incorporated technological experiments like on-board structural dynamic experiment, thermal control coating experiment and vibration beam accelerometer. With a lift-off mass of about 2,180 kilograms (4,810 lb), the spacecraft was to have generated a maximum of 2,760 W of power.[4][5]
GSAT-4 was also to have been the first Indian spacecraft to employion propulsion.[4] FourHall-effect thrusters would have been used for north–south station keeping operations. Two types of Hall-effect thrusters are developed by ISRO Satellite Centre (ISAC) and Liquid Propulsion Systems Centre (LPSC).
GSAT-4 carried the firstGPS Aided Geo Augmented Navigation, or GAGAN, navigation payload. GSAT-4 was also intended to carry to theIsraeliTAUVEX-2 space telescope array. Due to concerns that the new upper stage may have reduced the rocket's payload capacity, ISRO decided to remove TAUVEX in order to decrease the mass of the payload.[5] GAGAN was still flown.[5] GAGAN consisted of a Ka bandbent pipe transponder and a regenerative transponder.[6]
GSAT-4 was launched on the maiden flight of the GSLV Mk.II rocket, GSLV-D3, flying from theSecond Launch Pad at theSatish Dhawan Space Centre. Its third stage was fitted with a new Indian-builtcryogenic engine, which was intended to make the GSLV reliant on only Indian technology, since earlier launches had used Russian engines. GSLV-D3 was the sixth flight of theGeosynchronous Satellite Launch Vehicle across all variants.
The rocket was 40.39 metres (132.5 ft) in length minus its payload fairing, and consisted of a solid-fuelledS139 first stage augmented by fourL40Hhypergolically fuelled strapons, burningUDMH as fuel andN2O4 as oxidiser. The second stage used the same hypergolic propellants, whilst the third stage was the newCryogenic Upper Stage (CUS), burningliquid hydrogen oxidised byliquid oxygen.
The rocket's first and second stages performed normally, and at the time controllers reported that third stage ignition had occurred. However, shortly afterwards the rocket began to under-perform, tumbling out of control, and deviating from its planned trajectory.[7] Around 300 seconds into the flight, contact with the rocket was lost. Initial analysis of the data suggested that thevernier thrusters, used to provideattitude control, had failed to ignite due to engineering problems.[2] On 17 April, ISRO announced that further analysis of the data indicated that the third stage main engine had not ignited either.[3] According to ISRO, the mission failed after theturbopump that supplied fuel to the cryogenic engine had stopped working one second after ignition.[8]
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