The GSLV-D3 flight that lifted-off from SDSC at 16:47 IST was unsuccessful. This led the vehicle to lose altitude and splash down into the Bay of Bengal. The exact reason for the failure is ascertained but the ISRO Chairman, Dr. K Radhakrishnan told the press that the problem could have with vernier engines of the upper stage.
The vehicle lifted-off at 16:47 IST and from here there are numerous reports of the vehicle terminating data transmission just after 505 seconds. The flight is said to have progressed normally upto the planned shut-down of S2 (2nd Stage) 293 seconds. Normally the S2 stage shut-downs at T +310 seconds at an altitude of 120 km and is jettisoned 4 seconds later at an altitude of 127 km. This is also when the cryogenic engine ignition takes place. But the parameters of the vehicle is said to have veered-out after T +293 seconds following a failure of the 2 vernier engines used to control the vehicle.
The vehicle is said to have got a velocity of 4.9 km per second as planned and the cryogenic stage ignition command was issued as planned by the on board computer. The terminal velocity (ie at the end third stage shut-down) of the GSLV is 10.2 km/sec at an altitude of 195 km.
The Chairman of ISRO told the press that, ”Indications are that the cryogenic engine got ignited”. But the vehicle started tumbling, due to loss of control, lost altitude and finally splashed down into the sea. This could have been caused by the ignition failure of the two vernier engines. These small thrusters are used for altitude control and adjustments in velocity.
The flight was the maiden one for the new Chairman of ISRO. The Chairman indicated at failure of vernier engines but he said that detailed analysis of the flight data is being carried out to find out the exact reasons for the failure and that corrective measures would be taken for the next test flight, scheduled to take place within a year.
Here is ISRO's official press release on the flight.
