Gaganyaan Low Altitude Escape Motor (LEM) Static Test
Another important milestone in the Gaganyaan project is completed, by successfully test-firing the Low Altitude Escape Motor (LEM) of Crew Escape System, from Sriharikota on August 10, 2022.
The Crew Escape System (CES) takes away the Crew module of Gaganyaan mission in case of any eventuality and rescues the astronauts.
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 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.
The main objectives of the static test is to evaluate motor ballistic parameters and to validate motor subsystem performance and to confirm the design margins. Test also evaluates the thermal performance of nozzle liners; especially to confirm the erosion ablative characteristics.
According to ISRO officials, test also measured the head-end mounted safe arm (HMSA) based ignition system performance. It is important to evaluate the side thrust due to misalignment and variation in flow and other functional parameters including flow reversal.