By Venkatachari Jagannathan

Sriharikota (Andhra Pradesh) Jul 15 (IANS): There is many a slip between the cup and the lip, goes the proverb and which has proved true for the Indian space agency that had to call off its Rs 978 crore moon mission, the Chandrayaan-2, an hour before the rocket's flight on Monday due to a technical snag.

The Chandrayaan-2 spacecraft was to be carried by India's heavy lift rocket Geosynchronous Satellite Launch Vehicle-Mark III (GSLV-Mk III).

To date India has flown 16 GSLV rockets (Mk I, II and III) and the total number of successful and failed missions are 12 and four respectively.

Last minute mission postponement has taken place in the past involving GSLV rockets.

For instance, the GSLV-D5 that successfully launched GSAT-14 in January 2014 gave tension to ISRO officials.

Originally it was scheduled for launch on August 19, 2013. Just hours before the blast off, fuel started leaking from its second stage or engine.

An ISRO official then had said that the second stage was replaced with a new one built with a different metal. He then added that some critical components in the four strap-on motors of the first stage was also replaced as a matter of precaution.

Similarly, the 2007 flight of GSLV rocket gave anxious moments to ISRO officials. Fifteen seconds before the lift-off, the rocket's computers put GSLV on hold detecting anomalies in the cryogenic fuel stage.

The launch was postponed by two hours to set right the problem even as ISRO officials were considering rescheduling the launch by another two days.

However, the detection of one of the vent valves in the cryogenic engine that had not shut properly led to its immediate rectification.

That apart, ISRO scientists were on tenterhooks till the last moment as for few seconds during the final cryogenic stage signals from the rocket failed to reach the ground stations.