ISRO puts off GSLV launch

Delay due to minor leak in cryogenic stage

In a terse announcement, the ISRO said the launch of the GSLV-FO6 with India’s latest communication satellite “GSAT-5P,” scheduled for December 20, has been postponed “due to a minor leak in one of the valves of the Russian cryogenic stage, observed during pre-countdown checks.”

The 29-hour countdown sequence planned to commence at Sriharikota at 11 am on Sunday was not authorised by the “Launch Authorisation Board” that met this forenoon to review the results of the pre-countdown checks, the ISRO’s statement said.

Schedule

The revised schedule for the launch would be firmed up after ascertaining the cause of the leak, remedial actions and due verifications, the ISRO said. Given the multiplicity of the task, this could take at least three weeks. The third stage of the “GSLV-FO6” uses a cryogenic engine that is much more efficient and provides more thrust for every kilogram of propellant it burns, compared to other solid and liquid propellants.

But it is the cryogenic stage that has been creating the jinx for ISRO’s GSLV flights even in the past. For instance, the “GSLV-D3” launched from Sriharikota on April 15 earlier this year was unsuccessful though subsequent Polar Satellite Launch Vehicle (PSLV-C15) in July didn’t disappoint.

The “GSLV-D3,” which was the sixth GSLV flight for ISRO, was the first flight to test the indigenously-developed Cryogenic Upper Stage (CUS). The failure analysis committee of the ISRO found that it crashed due to the “failure of the fuel booster turbo pump of the indigenous CUS.”

Even as ISRO had planned its next flight testing of a GSLV with indigenous CUS within a year, the launch scheduled for Monday was to be with a Russian made cryogenic engine. However, according to ISRO, other major changes in the launch vehicle had been incorporated in “GSLV-FO6,” compared to the previous flight.