IRNSS-1H failure likely caused due to snag in explosive bolts

Indian Space Research Organization (ISRO) scientists have said that they suspect a snag in explosive bolts used to separate the heat shield from the satellite as being the reason behind failure of IRNSS-1H satellite.

The IRNSS-1H satellite failed to separate from the PSLV rocket after its launch from Sriharikota and while this kind of failure is rare, ISRO scientists say they are going to carry out an in-depth analysis to detect the root cause of the anomaly.

Former ISRO group head Chivukula Ravindhranath said that the heat shield (also called fairing) separation on launch vehicles is generally very reliable, and scientists don’t even consider this type of failure as a possible risk. According to Ravindhranath, everything related to heat shield separation has a back-up system except for the explosive material used in the bolts.

Before the launch a number of tests are performed on the heat shield to guarantee successful separation. The heat shield is an encasement that protects the satellite in the rocket. Once the rocket is in orbit, the heat shield separates and releases the satellite in space.

The heat shield normally separates as a result of the bolts that explode and split the fairing into two halves and pushes these away from the rocket to avoid damaging the satellite.

Mr Ravindranath says there have been instances of a total failure of a mission when the heat shield of the rocket failed to open. On November 30, 1970, an Atlas Centaur rocket launched in the US failed to release the satellite as a faulty explosive latch prevented the heat shield from separating.

In August 2009, the Science and Technology Satellite-2 (STSAT-2) on South Korea’s Space Launch Vehicle’s (KSLV-1) maiden flight failed to achieve orbit because the rocket’s payload fairing did not separate as planned.

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