ISRO successfully completes Gaganyaan LEM static test

Low Altitude Escape Motor (LEM): In another important milestone in the Gaganyaan project, Indian Space Research Organization (ISRO) recently carried out the test-firing of the Low Altitude Escape Motor (LEM) of Crew Escape System successfully.

Key Points:

  • The test firing of LEM was carried out from Sriharikota, Andhra Pradesh.
  • The Crew Escape System (CES) takes away the crew module of the Gaganyaan mission in case of any eventuality and rescues the astronauts.
  • In case of aborting the mission during the initial phase of flight, LEM provides the required thrust to CES to take away the crew module from the launch vehicle.


The main objectives of the static tests as listed by ISRO are:

  • To evaluate motor ballistic parameters.
  • To validate motor subsystem performance and to confirm the design margins.
  • To evaluate the thermal performance of nozzle liners; especially to confirm the erosion / ablative characteristics.
  • To validate integrity of all interfaces.
  • To evaluate the head-end mounted safe arm (HMSA) based ignition system performance.
  • To evaluate side thrust due to misalignment and variation in flow and other functional parameters including flow reversal.

About LEM:

  • The LEM is a distinctive special purpose solid rocket motor.
  • It has four reverse flow nozzles and generates a maximum sea level thrust of 842 kN (nominal) with a burn time of 5.98 seconds (nominal).
  • The nozzle end of LEM is mounted at the fore end of the launch vehicle unlike at the aft end in conventional rocket motors to avoid exhaust plume impingement on the 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.

About Gaganyaan Mission:

  • Gaganyaan Mission is India's maiden space mission.
  • The mission is expected to be launched in 2023.
  • Prime Minister Narendra Modi, on August 15, 2018 had formally announced the Gaganyaan initiative during his Independence Day speech.

With this launch, India will become the fourth nation in the world to launch a Human Spaceflight Mission after the USA, Russia and China.

Under the Gaganyaan schedule:

  • Three flights will be sent into orbit.
  • Two will be unmanned flights while one will be human spaceflight.
  • The Orbital Module will have three Indian astronauts, including a woman.
  • It seeks to circle Earth at a low-earth-orbit at an altitude of 300-400 km from the earth for 5-7 days.

Note: ISRO will send humanoid Vyom Mitra in unmanned Gaganyaan spacecraft ahead of human spaceflight (Monitoring module parameters).

About Gaganyaan:

  • Gaganyaan is an Indian crewed orbital spacecraft that is intended to send 3 astronauts to space for a minimum of seven days by 2022 (delayed due to COVID-19).
  • It was launched by ISRO's Geosynchronous Satellite Launch Vehicle GSLV Mk III (3 stages heavy-lift vehicle).
  • It consists of a service module and a crew module, collectively known as an Orbital Module (Crew Module carries astronauts & Service Modules carries propellants).

About ISRO:

  • Indian Space Research Organization (ISRO) is the space agency of the Government of India (GoI).
  • It was formed in 15 august 1969.
  • It superseded the erstwhile “Indian National Committee For Space Research” (INCOSPAR) which was established in 1962 by the efforts of Independent India's first prime minister‚ Jawaharlal Nehru‚ and his close aide and scientist Vikram Sarabhai.