Introduction

Indian Space Research Organisation (ISRO) has achieved a significant breakthrough in its quest for human spaceflight with the successful human rating of its CE20 cryogenic engine.
The ground qualification tests, conducted at the High Altitude Test Facility at ISRO Propulsion Complex, Mahendragiri, have been successfully completed, validating the CE20 engine for the Gaganyaan programme.

What is Cryogenic Engine?

It is a type of rocket engine that operates on cryogenic (extremely low-temperature) fuels and oxidizers, typically liquid hydrogen (LH2) and liquid oxygen (LOX).
They are highly efficient due to the high energy density of cryogenic fuels.
They provide greater thrust compared to traditional rocket engines, making them suitable for launching heavy payloads into space.
They are commonly used in the upper stages of space launch vehicles, where they propel payloads from initial launch phases into desired orbits.
They operate at extremely low temperatures, typically below -150°C (-238°F) for liquid hydrogen and below -183°C (-297°F) for liquid oxygen.

It has been designed and developed by the Liquid Propulsion Systems Centre (LPSC), a subsidiary of ISRO.
It is the first Indian cryogenic engine to feature a gas-generator cycle.
It is one of the most powerful upper-stage cryogenic engines in the world.
This engine develops a nominal thrust of 186.36 kN in vacuum.

Thorough Evaluation: The CE20 engine underwent extensive testing, including evaluation under nominal and off-nominal conditions related to thrust, mixture ratio, and propellant tank pressure.
Hot Firing Tests: Four engines underwent a total of 39 hot firing tests, accumulating a cumulative duration of 8,810 seconds, surpassing the minimum human rating qualification standard requirement of 6,350 seconds.

Mission Objectives: The Gaganyaan project aims to demonstrate India’s human spaceflight capabilities by launching a crew of three members into a 400 km orbit for a 3-day mission, followed by a safe return to Earth with a landing in Indian sea waters.
Acceptance Tests: ISRO has completed the acceptance tests of the flight engine designated for the first unmanned Gaganyaan (G1) mission, scheduled tentatively for the second quarter of 2024.
Engine Specifications: The flight engine, which will power the upper stage of the human-rated LVM3 vehicle, boasts a thrust capability of 19 to 22 tonnes and a specific impulse of 442.5 seconds.