Did ISRO goof up on GSLV?

Two days after ISRO’s geosynchronous satellite launch vehicle (GSLV) mission failed, the agency is now trying to figure out what went wrong with the rocket.

The agency, initially, wondered whether it was the failure of an actuator or the snapping of the first stage connectors that led to the second consecutive failure of the (GSLV) on Christmas day; but the scientists are now thinking whether five days was too short to correct the defect that was first noticed on December 20.

The GSLV mission was postponed from December 20 – when a ‘minor’ leak in one of the valves of the Russian cryogenic engine as detected – to December 25, when it failed.

Sources in ISRO told DNA that when a leak in the upper stage cryogenic engine (the last stage engine that takes the capsule carrying the satellite to its predetermined location in space) was plugged, an overall check of the first stage, too, should have been conducted to ensure a successful launch.

“But five days was not enough to do all that; and, obviously, it now appears that we overlooked the problem in the first stage itself,” said a scientist involved with the mission.

The GSLV-F06 rocket, carrying the advanced Rs125 crore GSAT-5P communication satellite lacked thrust and veered off course barely 50 seconds after the 4.04pm lift-off on December 25, forcing the scientists at the Satish Dhawan Space Centre in Sriharikota to press the self-destruct button and explode the satellite. This happened 63 seconds after lift-off.

Interestingly, the very first attempt to launch the GSLV programme on March 28, 2001, was also aborted a second before lift-off due to a snag.

It was rescheduled for April 18, 2001 – 21 days after the original date – when it was successfully launched to mark the beginning of India’s GSLV series of launchers. The problem then was the lack of thrust due to defective plumbing in one of the four first stage strap-on engines.

However, former ISRO chairman and current chairman of governing council of Physical Research Laboratory (PRL), Ahmedabad, Prof UR Rao told DNA that everything had been monitored and that the problem arose seconds after the launch, catching the scientists unawares.

“The actuator seems to have failed to receive commands from the onboard computer of the rocket,” he said. The actuators are linked with the rocket motor, the failure of which may have caused GSLV-F06 to veer off course and break up.

ISRO chairman K Radhakrishnan said the scientists were also verifying whether it was the snapping of first stage connectors of the GSLV-F06 that led to the failure of the mission.

“There are hundreds of pages of data pertaining to a few seconds after the lift-off that the scientists have to study. Only then can we arrive at the precise problem that led to aborting the mission,” said Prof Rao.