The launch of the earth observation satellite EOS-03 aboard the Geostationary Launch Vehicle (GSLV F-10) failed on August 13 after the third stage of the rocket did not ignite due to a “technical anomaly,” the space agency said at the time.

The GSLV is a three-stage rocket, with the first stage using solid fuel, the second stage using liquid fuel, and the third stage using cryogenic fuel – gases stored in liquid form at extremely low temperature – that enhances the carrying capacity of the rocket.

The GSLV-F10 launch in August failed due to a small loss in pressure in the cryogenic upper stage of the launch vehicle, according to officials from the Indian Space Research Organisation (ISRO). The space agency is yet to publicly release a summary or the failure analysis report of the mission.

“The reason for the GSLV F-10 failure was a 50 millibar reduction in the LH-2 tank pressure,” said Dr V Narayanan, director of ISRO’s Liquid Propulsion Systems Centre, during his quality day celebration address at the Vikram Sarabhai Space Centre.

The launch of the earth observation satellite EOS-03 aboard the Geostationary Launch Vehicle (GSLV F-10) failed on August 13 after the third stage of the rocket did not ignite due to a “technical anomaly,” the space agency said at the time. Usually, a review of what went wrong is undertaken by a committee after any launch failure.

The GSLV is a three-stage rocket, with the first stage using solid fuel, the second stage using liquid fuel, and the third stage using cryogenic fuel – gases stored in liquid form at extremely low temperature – that enhances the carrying capacity of the rocket.

In any cryogenic engine – like the one in GSLV that uses liquid oxygen and hydrogen as a fuel – the pressure inside the fuel tank needs to be maintained for a smooth flow of the fuel to the engine, preventing the tank from collapsing. Helium is added to the cryogenic engine as the fuel is used up to maintain pressure. The launch of Chandrayaan-2 in July 2019 was aborted last minute because there was a helium leak in the cryogenic stage that was detected during the pre-flight checks.

This was the first major failure of the GSLV vehicle since 2010, when two consecutive malfunctions took place, earning the rocket the epithet “naughty boy”. For ISRO, this was the only launch failure since the 2017 PSLV launch when a heat shield that protects the satellite within did not separate.

The mission was delayed twice – once in March 2020 when the space agency said that there were technical glitches, and then again in March this year when the second wave of the pandemic hit. The GSLV F10 was only the second mission of 2021, and since the failure, the space agency hasn’t undertaken any launches.