IRNSS-1H satellite on PSLV C39 launch: The launch of navigation satellite IRNSS-1H, aimed at expanding the existing seven satellites capabilities of the NavIC constellation, failed after take off at 7 pm from Sriharikota's rocket port in Andhra Pradesh. Addressing a press conference soon after the mission failed, ISRO chief A S Kiran Kumar said, \u201cLaunch mission has not succeeded. Heat shield has not separated as a result of which satellite is inside the 4th stage.\u201d This was ISRO's first unsuccessful lift off since 1993 as the PSLV failed to deploy payload. \u201cWe are getting into the details of what has happened. This has been an unsuccessful mission,\u201d Kumar said further. \u201cThere is no problem in any of the stages, but heat shield has to separate and once that happens it gets into the orbit,\u201d explained the ISRO chief adding that satellite got separated internally, but it is enclosed within the heat shield in fourth stage. The PSLV-C39, like the previous six launches of IRNSS satellites, used the \u2018XL\u2019 version of the PSLV equipped with six strap-ons with each carrying 12 tonnes of propellants. ISRO began the 29-hour countdown for the launch on Wednesday evening at Sriharikota which is about 80 km northeast of Chennai. The launch took place from Second Launch Pad (SLP) of the Satish Dhawan Space Centre (SDSC). The countdown of the launch was cleared on August 29 by the Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB). According to a report by Indian Express, the IRNSS-1H was aimed at replacing the IRNSS-1A in a seven-satellite Indian navigation constellation after the failure of the IRNSS-1A due to some defects in the three atomic clocks on the satellite which are considered important in order to provide positional information.