In a significant development for India's upcoming maiden human spaceflight mission 'Gaganyaan', the Indian Space Research Organisation (ISRO) has successfully test-fired the Low Altitude Escape Motor (LEM) of the Gaganyaan mission's Crew Escape System from Sri Harikota in Andhra Pradesh on Wednesday (10 August).

"The Crew Escape System (CES) takes away the Crew module of Gaganyaan mission in case of any eventuality and rescues the astronauts," ISRO said in a statement.

In case of mission-abort during the initial phase of flight, LEM provides required thrust to CES, to take away crew module from the launch vehicle.

LEM is a distinctive special purpose solid rocket motor with four reverse flow nozzles and generates maximum sea level thrust of 842 kN (nominal) with burn time of 5.98 s (nominal), the space agency said.

The nozzle end of LEM is mounted at the fore end of the launch vehicle unlike at aft end in conventional rocket motors to avoid exhaust plume impingement on crew module. This necessitates the use of a reverse flow multiple nozzle in this solid rocket motor. The reverse flow nozzle implies the reversal of the exhaust gas flow direction in the nozzle region, ISRO said.

The main objectives of the static test included evaluation of motor ballistic parameters; validation of motor subsystem performance and to confirm the design margins; evaluation of the thermal performance of nozzle liners, especially to confirm the erosion/ablative characteristics; validation of the integrity of all interfaces; evaluation of the head-end mounted safe arm (HMSA) based ignition system performance.

Further, the test also evaluated side thrust due to misalignment and variation in flow and other functional parameters including flow reversal.