The successful flight of the Geosynchronous Satellite Launch Vehicle (GSLV) on Thursday evening marks an important milestone in India’s journey towards achieving full capability to launch heavier satellites.
With today’s launch, GSLV has entered its operational phase giving Indian Space Research Organisation (Isro) much needed lift power. It was the third consecutive successful flight of indigenously built rocket with the crucial cryogenic upper stage engine, and the first one officially described as ‘operational’ as opposed to earlier ‘developmental’ flights. Incidentally, it was seventh successful launch from the Satish Dhawan Space Station at Shriharikota this year.
Designated as GSLV Mark II, the rocket propelled an advanced weather satellite, INSAT- 3DR, weighing 2,211 kg into its designated orbit at the end of the flight lasting a little over 17 minutes. The GSLV flown on Thursday was similar in configuration to the two developmental missions that took place in January 2014 and August 2015.
This gives Indian space agency the capability to inject 2 ton to 2.5 ton class satellites into Geostationary Transfer Orbit (GTO). For launching satellites that weigh up to 4 tons, Isro is working on the next version – GSLV Mark III, test flight of which is likely in a few months. GSLV Mark III will also be used for launching the lunar mission, Chandrayaan-2. Meanwhile, the agency plans more flights of GSLV II in order to establish this as a robust launcher. Polar Satellite Launch Vehicle (PSLV) is capable of launching satellites weighing below 2 tons. With over 30 consecutive successful launches, PSLV is now a commercial launcher. From this point of view, GSLV has a long way to go.
It has taken more than two decades for Isro to induct full-service GSLV into its fleet of rockets. Since 2001, the agency has launched a total of ten GSLVs – six with cryogenic engine supplied by Russia and four with indigenously developed cryogenic engine. It has been a mixed bag of success. Two GSLV flights with Russian engine were unsuccessful while a third mission was partial success. Of the four GSLV flights with indigenous cryogenic stage (including the latest one), three have been successful. The first flight of GSLV with indigenous upper stage one in April 2010 had failed. The mission had failed even before ignition of the cryogenic stage.
The efforts to develop a rocket with cryogenic propulsion began in the 1990s. Initially it was planned to procure cryogenic engines and technology from American aerospace firms. When this did not materialise for commercial and strategic reasons, India opted engines from Russian space agency Glavkosmos. Russians first agreed to supply cryogenic engines and transfer technology, but backed off under American pressure. Glavkosmos finally only supplied six cryogenic engines and the first flight of GSLV with Russian upper stage took place in 2001. Along with GSLV flights with Russian cryogenic engine, Isro has been developing its own cryogenic technology for rockets named – GSLV Mark II and Mark III.
Cryogenic propulsion is technically challenging and is considered a strategic technology. It is key to the success of any robust space programme because it allows heavier payloads to be carried into space more efficiently. A cryogenic rocket stage provides greater thrust for every kilogram of propellant it burns, compared to solid and liquid propellant rocket stages. It is strategic because it gives the space agency capability to be independent and also become a commercial player. Just a handful of countries possess this critical engine technology.
A rocket with cryogenic engine is referred to as ‘icy hot’ because when the lower stages of the rocket with solid and liquid fuels are igniting with temperature reaching 3,000 degrees and more, the upper cryogenic stage remains super cooled at -250 degrees and more. Thousands of liters of liquid oxygen and liquid hydrogen remain encased in massive chambers – till the cryogenic stage gets ignited. Cryogenic stage in rocket is much more efficient and provides more thrust for every kilogram of propellant it burns compared to solid and liquid propellant stages.
The INSAT-3DR launched by GSLV on Thursday has been designed to provide a variety of meteorological services to the country. It has several advanced payloads like Data Relay Transponder and Satellite Aided Search and Rescue Transponder. Its imager will generate images of the earth disk from altitude of 36,000 kilometers every 26 minutes and provide information on various parameters sea surface temperature, cloud motion winds, snow cover etc.