Indian space agency ISRO successfully tested indigenous cryogenic engine of 4-tonne capacity on Tuesday at Mahendragiri Propulsion Complex in Tamil Nadu, making it viable to send heavy load satellites weighing up to 4 tonnes now.
Congratulating the Indian Space Research Organisation, Prime Minister Narendra Modi said in his Twitter message: “The engine tested today will enable us to put satellites of up to 4 tons in geostationary orbit. A proud accomplishment.”
Today’s test was carried out to see whether the indigenous cryogenic engine developed has the exact thrust required to launch payloads of 3 to 4 tonne capacity. Since the test was successful, ISRO is upbeat to take up the next phase where it can test how the cryogenic engine cane be fitted on a GSLV Mar III workhorse.
In fact, developing cryogenic engine began three decades ago when India was carrying out space programs almost in isolation with ISRO sanction stifling its growth in the late 1990s over Pokhran nuclear tests.
Though the Geosynchronous Satellite Launch Vehicle (GSLV Mark III) was tested successfully to carry out re-entry capsule few months ago, the engine used was a passive cyrogenic one and the current test completes the cryogenic engine design for future heavy load missions.
The first cryogenic engine was used in January 2014 when GSLV-D5 was launched and with today’s launch it can ponder any heavyload satellite easily and even command a bigger share in the global market for such launches.
A Cryogenic engine provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellant rocket stages, which were used till now by ISRO. Specific impulse (a measure of the efficiency) achievable with cryogenic propellants (liquid Hydrogen and liquid Oxygen) is much higher compared to earth storable liquid and solid propellants, giving it a substantial payload advantage, explains ISRO.
But cryogenic engines involve a very complex system due to its use of propellants at extremely low temperatures. Oxygen liquifies at -183 deg C and Hydrogen at -253 deg C and the propellants, at these low temperatures are to be pumped using turbo pumps running at around 40,000 rpm.
It also entails complex ground support systems like propellant storage and filling systems, cryo engine and stage test facilities, transportation and handling of cryo fluids and related safety aspects, said ISRO on its website.
ISRO’s current Cryogenic Upper Stage Project (CUSP) effectively replaces the design of the Cryogenic Upper Stage procured earlier from Russia and used in GSLV flights. The main engine and two smaller steering engines of CUS together develop a nominal thrust of 73.55 kN in vacuum. During the flight, CUS fires for a nominal duration of 720 seconds, explained ISRO note.
“Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) from the respective tanks are fed by individual booster pumps to the main turbopump to ensure a high flow rate of propellants into the combustion chamber. Thrust control and mixture ratio control are achieved by two independent regulators. Two gimbaled steering engines provide for control of the stage during its thrusting phase,” explained ISRO about the project.