05/06/2017 12:59 PM IST | Updated 05/06/2017 12:59 PM IST

All You Want To Know About ISRO's GSLV Mark III Launch Today

The rocket can carry payloads of up to 4,000 kg.


Today at 5:28 PM, Indian Space Research Organisation's GSLV (Geosynchronous Launch Vehicle) Mark III rocket will be launched into orbit. This is a historic moment for Indian space research as GSLV Mark III is the heaviest rocket launched by ISRO yet. Here are the details of the launch vehicle —


Height: 43.43 metres

Vehicle Diameter: 4 metres

Number of stages: 3

Payload capacity (Lower orbit earth): 8,000 kg

Payload capacity (Geosynchronous Transfer Orbits): 4,000 kg

Satellite on board: GSAT-19

Weight of the satellite: 3,136 kg

Total lift-off mass of the rocket: 640 tons.

History and Development

ISRO launched the first GSLV satellite in 2001 with an initial payload capacity of 1,500 kg. Later, the payload was upgraded to 1,900 kg with another version. Nine years and five flights later, the second iteration of the series, GSLV Mark II, was introduced with a payload capacity of 2,200 kg. ISRO is still using GSLV Mark II.

A total of five Mark II flights have been undertaken, out of which four were successful. The last was the successful launch of the SAARC satellite on 5 May, 2017.

Work on Mark III began early in the millennium but there were many obstacles. One key challenge was developing a homegrown cryogenics engine.

India wanted to import the engine from Russia all the way back in 1991 but pressure from the US had seen the deal bite the dust. However, in 2014, India was able to launch a GSLV with an indigenous cryogenic engine.

Mark III's first experimental flight was successfully performed on 18 December 2014. A series of tests followed to ensure that the different stages of the rocket were working. As reported by TOI, the total project cost is estimated to be at ₹2,900 crore.

The Tech behind vehicle

A cryogenic rocket engine uses liquid fuel stored at very low temperature. ISRO has developed an engine called CE-20 that uses liquid hydrogen at -253-degree celsius and liquid oxygen at -195-degree celsius. Because of the low temperatures required, developing the engine is a challenging feat.

The height of the rocket's upper stage is 25 metres and it carries 28 tons of cryo fuel. The current engine has 20 tons of thrust as compared to 12 tons of thrust achieved previously.

The rocket has been designed with an ogive shaped curvature so that it is robust and its air pressure is controlled. It also has an acoustic suppression system to keep the noise levels low.

As reported by the Ken (paywall), while ISRO has started using the electric propulsion system to increase the rocket's payload capacity, it is still using it only partially.

"With electric propulsion, it is possible for us to look at the equivalent of a six-tonne class [satellite] in a four-tonne satellite," ISRO Chairman AS Kiran Kumar had told the Ken.

The impact

If the GSLV Mark III launch is successful, India will be able to launch heavy satellites on its own. Other improvements, currently in the pipeline, will enable Mark III to carry heavier payloads. Up until now, ISRO has relied on European Space Agency's (ESA) Ariane 5 rocket to launch satellites with larger mass.

At 2,230 kg, the SAARC satellite launched last month has been ISRO's heaviest payload so far. Today's launch is carrying many hopes and expectations.