ISRO successfully test cryogenic engine of GSLV Mark 3 rocket

• The Indian Space Research Organisation (ISRO) has successfully conducted hotbed test of the indigenously developed high-thrust cryogenic engine (CE20) of the GSLV Mark 3 (LVM3) rocket for the upper stage.
• The long-duration test was conducted at ISRO Propulsion Research Centre at Mahendragiri, Tamil Nadu and lasted for 640 seconds.
• It was conducted with Mixture Ratio Controller (MRC) in a closed loop mode.
• Last year, the first developmental engine completed different hot tests in various operating regimes. The third engine identified for flight use will be vacuum tested in the high altitude test facility as part of the flight acceptance test.
• The biggest rocket made in India, the Mk3 will be capable of launching four-tonne satellites into geosynchronous orbit.
• There will be first developmental flight of the GSLV Mark 3 in December 2016.

About GSLV(Geosynchronous/Geostationary Satellite Launch Vehicle):

• It is a three-stage vehicle with solid, liquid and cryogenic stages respectively.
• The first stage, GS1, comprises a solid propellant motor (S125) and four liquid propellant strap-on stages(L40). (Fuel same as that of PSLV).
• The second stage of GSLV is the Vikas liquid propulsion system as in PSLV.
• Third stage uses cryogenic engine.

About Cryogenic Engine

• Cryogenics is the science pertaining to very low temperatures and includes super-low temperatures of - 150 degree Celsius to - 273 degree Celsius, the latter being called the ‘absolute zero’ temperature.
• These are temperatures where gases such as Oxygen, Nitrogen and Helium are liquified. Such liquified gases, at their super-cool temperatures find application in areas like super-conductivity, in cryo-medicine and cryo-surgery (surgery carried out at very low temperatures) and rocket propulsions (where they are used as super-cooled propellants).
• The difference between an ordinary liquid rocket and cryogenic rocket is in the fact that the oxidiser and fuel used in the cryogenic engine is only liquid at below freezing temperatures, whereas in the ordinary liquid rocket the fuel and oxidiser are liquid at ambient temperatures.
• Cryogenic engines, thus, are rocket engines which use super-cooled liquids as propellants. These engines use liquid Oxygen and liquid Hydrogen as fuels and the use of such engines provides greater thrust and higher degree of control.
• Experiments have been tried out with kerosene and liquid oxygen. This was a quasicryogenic engine experiment. It would not be difficult to convert this into a cryogenic engine.
• Liquid Oxygen (LOX) was the earliest, cheapest, safest and, eventually, the most preferred oxidiser for large launch vehicles. In later years, among the semi-cryogenics, LOXKerosene combination was found to be the best and is currently preferred worldwide for its price, safety, least toxicity and specific impulse.
• All the leading rocket visionaries identified liquid hydrogen (LH2) as the theoretically ideal rocket fuel. Its combination with LOX gives the highest specific impulse with the least toxicitythe LOX-LH2 rocket exhausts essentially steam.
• Cryogenic propellants, semi-cryogenic propellants and storable liquid propellants, in the decreasing order- are of higher specific impulse than solid propellants. Mostly, LOX-Kerosene and LOX-LH2 are being adopted in the construction of new launch vehicles for large satellites (i.e., 2000kg and above).
• In February 1998, ISRO successfully tested an indigenously designed cryogenic engine for about a minute at its Mahendragiri centre (Tamil Nadu).
• The thrust chamber of the engine, in which liquid Hydrogen (LH2) and liquid Oxygen (LOX) burns, is cooled by passing liquid hydrogen through channels milled into the wall of the thrust chamber.
• The technique for making this channel was developed at the Central Electrochemical Research Institute at Karaikudi (Tamil Nadu).
• The test shows that the ISRO has mastered the process for firing a cryogenic engine.

By: Vishal