BANGALORE, India — Launch of an Indian telecommunications satellite was postponed Dec. 19 after a helium leak was detected in rocket’s upper stage a day before liftoff .

The GSAT-5P telecommunications satellites had been slated to launch Dec. 20 from Sriharikota aboard an Indian Geosynchronous Satellite Launch Vehicle (GSLV) equipped with a Russian-supplied cryogenic upper-stage engine.

“The launch has been postponed due to a minor leak in one of the valves of the Russian cryogenic stage observed during the pre-countdown checks,” the Indian Space Research Organisation (ISRO) said in a Dec. 19 statement. As a result the 29-hours countdown sequence planned to commence Dec. 19 at 11:00 a.m. local time not was not initiated, ISRO spokesman S. Satish told Space News.

In its statement, ISRO said a new launch date would be set “after ascertaining the cause for the leak, remedial actions and due verifications.”  Satish said ISRO would consult the engine’s Russian suppliers over the next few days for help identifying and rectifying the problem.

Weighing 2,310 kilograms, the GSAT-5P would be the heaviest satellite the GLSV has carried into orbit. The GSLV has launched five times to date using the Russian cryogenic stage. The first GSLV employing an Indian-built cryogenic upper stage crashed in its April debut when the engine failed to ignite.

The  GSAT-5P satellite will carry 24 C-band and 12 extended C-band transponders and is designed to replace the INSAT-2E  communications and weather satellite launched by a European Ariane 4 rocket in 1999.

Satish said the launch delay would not affect Indian telecommunications services.

Based in Bangalore, Killugudi S. Jayaraman holds a doctorate in nuclear physics from the University of Maryland and a master's degree in journalism from the Medill School of Journalism at Northwestern University. He was formerly science editor of the...