After two failures of its heavy lift Geosynchronous Satellite Launch Vehicle (GSLV) in April and December last year, India is taking a cautious approach to resuming launch operations of the vehicle, delaying a planned first-quarter mission for its workhorse Polar Satellite Launch Vehicle (PSLV.
The Indian Space Research Organisation (ISRO) says a PSLV launch schedule is awaiting tests of the high-temperature tolerance level of a key component of the vehicle.
Featuring four alternate liquid- and solid-fuel stages - including one of the world's largest sold-fuel boosters - the 44.9m (147ft)-tall PSLV is ISRO's first operational launch vehicle and has a sound track record of carrying out multiple launches, including a run of 16 successful flights up to its last mission in July 2010.
The future of the heavier GSLV - and with it India's manned and Moon mission plans - depends on an Indian-developed cryogenic upper stage whose failure ended the April 2010 mission after 293s. Russian-built stages have been used for other flights, but are no longer available.