The Geo-Synchronous Satellite Launch Vehicle Mark III ahead of its launch

India's space agency is all set for one of its most ambitious tests as it readies for the unique maiden flight today of its heaviest rocket to date - the 630-tonne, three-stage rocket Geo-Synchronous Satellite Launch Vehicle Mark III.The rocket is scheduled to lift off at 9:30 am from the Satish Dhawan Space Centre in Sriharikota in Andhra Pradesh.This experimental flight marks a quantum shift in the rocket technology that India has mastered. The new three-stage rocket is capable of doubling the capacity of payloads India can carry into space. The rocket can deposit up to four tonne class of communication satellites into space. ISRO hopes this will become its mainstay rocket in the future. The rocket will later be suitably equipped for ferrying Indian astronauts into space.On this flight, the rocket will be tested on how it performs during its travel in the atmosphere. The rocket will have the first two stages as active rocket engines, while the third stage that consists of the cryogenic engine is a passive stage. The heavy-duty cryogenic enginenecessary for this rocket is still under development by ISRO. A full-fledged launch of the rocket can be expected in a few years.The GSLV Mk III is an altogether new design of rocket by Indian engineers. Incidentally, its first stage consists of twin solid-state rocket engines that carry as much as 200 tonnes of propellant each. "These are the world's third largest rocket boosters," said ISRO Chairman K Radhakrishnan.Once ISRO masters this rocket, there may not be any need for India to send its heavy-duty communications satellites to space using expensive foreign launchers. It can also hope to make a dent in the multimillion-dollar global commercial launch market.This flight is a two-in-one mission being undertaken by ISRO. The main passenger in the rocket is an Indian-made crew module. This marks the beginning of what could be India's initiation into the ambitious human space flight programme. While this crew module will be unmanned, the small room-sized cupcake-shaped satellite is indeed capable of carrying two or three astronauts into space. (India Gets Set for Flying Astronauts) In this flight, the crew module will be hoisted up to an altitude of about a 127 kilometres above Earth. The crew module is also powered by its own engine and will be navigated and made to re-enter the atmosphere at a massive velocity. It will then be slowed down using massive parachutes. Incidentally, the parachutes being used are the largest ever to be deployed by India.The crew module will then make a splash down near the Andaman Islands in the Bay of Bengal. In its flight, several parameters will be tested on the crew module; crucially, ISRO is very keen to understand how the crew module and it's outer lining made of special heat resistant tiles withstands the over-4,000 degree centigrade temperatures it experiences as it comes hurtling back to Earth.ISRO has proposed that it can fly Indian astronauts into space using an indigenous rocket from Indian soil within seven to eight years of getting a government nod for its astronaut programme. ISRO has sought funding of about Rs 12,500 crores for its human space flight endeavour. When it happens, India will become the fourth country in the world to have indigenous capability of sending humans into space; presently, Russia, USA and China are the only nations to have the necessary technology for this complex mission.

Earlier this year, the US' National Aeronautics and Space Administration or NASA tested its most modern crew module called Orion. Now, within a few weeks, ISRO is following up with its own version of a made-in-India crew module. The guiding principle it seems is, if NASA can, so can ISRO.This big launch is a watershed moment for ISRO and a real trial by fire as it charts new frontiers in space exploration.