Context: 

ISRO achieves human rating of CE20 cryogenic engine CE20 for Gaganyaan mission.

Successful Completion of Human Rating of CE20 Cryogenic Engine for Gaganyaan Mission

• ISRO has accomplished a major milestone in the human rating of its CE20 cryogenic engine, which powers the cryogenic stage of the human-rated LVM3 launch vehicle for Gaganyaan missions.
  • Human-rating refers to rating a system that is capable of safely transporting humans. 
    • The tests involved life demonstration tests, endurance tests, and performance assessments under nominal operating conditions as well as off-nominal conditions.
• The human-rated HLVM3 rocket consists of a crew escape system, crew module, and orbital module.
  • Crew Escape System (CES): It ensures that crew module along with the crew is taken to a safe distance in case of any emergency either at launch pad or during ascent phase.
  • Orbital Module (OM): It will be orbiting the Earth and comprises a crew module (CM) and a service module (SM). 
    • OM is equipped with state-of-the-art avionics systems with adequate redundancy for human safety.

CE20 Cryogenic Engine

• CE20 Cryogenic engine: It is a rocket engine that uses a cryogenic fuel and oxidizer, meaning that both of these components are liquefied gasses that are kept at extremely low temperatures.
• Fuel Used: It typically makes use of liquid oxygen (LOX), which liquefies at -183 deg C, and liquid hydrogen (LH2), which liquefies at -253 deg C.
  • LH2 acts as the fuel, while LOX acts as the oxidizer that explosively reacts with the hydrogen, producing thrust.
• Stage of Usage: They are highly efficient propulsion systems with increased payload capacity and are used in the upper stages of rockets. 
• Other Cryogenic Engines: ISRO has used three cryogenic engines over the years: KVD-1, CE-7.5, and CE-20. 
  • The last two are India-made, although the design of the CE-7.5 is based on the KVD-1, which the Soviet Union supplied to India in the early 1980s.

Significance of Cryogenic Engines: 

• Higher Payload carrying capability: These engines enable rockets to carry larger payloads, critical for complex missions including satellite deployment and interplanetary exploration
• Advanced Propulsion: Cryogenic rocket stage is more efficient and provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellant rocket stages.
• Technological Milestone: It is a significant achievement for ISRO, as only six countries have developed their own cryogenic engines: the US, France/European Space Agency, Russia, China, Japan, and India.