GSLV-Mark III maiden launch: One large step for ISRO, a giant leap for India as a global space power

Called “fat boy” or “monster rocket”, the 640-tonne Geosynchronous Satellite Launch Vehicle (GSLV) Mark III blasted off from Sriharikota in Andhra Pradesh at 5.28 pm on Monday, marking India's most significant milestone in space technology.



With this successful mission, Indian Space Research Organisation (ISRO) increased its capacity to launch satellites from 2.3 to 4 tonnes: By 70 percent.

This rocket can lift into a space a 4000-kilogram satellite in a geosynchronous transfer orbit of 36,000 kilometres above earth or one weighing 10,000 kilograms in a low-earth orbit 600 kilometres high.

The rocket uses indigenous CE-20 cryogenic engines, unlike the ones made earlier which were partly based on Russian technology. And it’s not just the rocket that went up on Monday that’s special, but even the satellite that went with it — GSAT-19— is a first for India; the first satellite that can provide internet connectivity from space.

The GSLV-Mark III flight means many things for India:

1. India becomes self-reliant— almost — in launching four-tonne communication satellites. It had earlier been depending on foreign rockets.

Though GSLV-Mark III is capable of launching 4,000-kilogram satellites, it was used on Monday to put in space GSAT-19, which weighs only 3,136 kilograms, because ISRO didn’t want to take chances with the rocket’s maiden flight. India has been so far using indigenous rockets — different variants of Polar Satellite Launch Vehicle (PSLV) and the Mark I and II versions of GSLV — to launch lighter satellites primarily meant for earth observation.

2. India joins a small club of heavy-lift satellite launchers. So far, only the space agencies of the US, Russia, France, China, Japan and Europe are capable of satellites weighing 4,000 kilograms and more.

3. This significantly expands India’s opportunities in the multi-billion dollar satellite launch market because India’s launch costs are significantly lower than its competitors. So far, India has been launching foreign satellites weighing much less than 4,000 kilograms.

4. By using fully-indigenous CE-20 cryogenic engines in the GSLV-Mark III, India has proved that it has achieved a significant degree of mastery over the very complex science of cryogenics. This will, no doubt, help India scale further heights in space technology, like, eventually sending a man to the moon.

5. The new capability will make it possible for India to help countries in the region launch their satellites as part of space diplomacy, which China is good at.

A difficult science

Cryogenics is a branch of physics which studies what happens at very low temperatures. A cryogenic rocket engine uses liquid hydrogen (LH2) as fuel and liquid oxygen (LOX) as oxidiser at very low temperatures. The technology isn't new: The US first test-fired a rocket using LH2 and LOX in 1961, and it helped the Americans send a man to the moon eight years later.

But the process is so complex that only a handful of countries are producing cryogenic engines. What further complicates matters is that hydrogen liquefies only at minus 253 degrees centigrade and oxygen at minus 184 degrees. If turning the two gases into liquids is tough, making the right kind of tanks that store them and the engines that receive them with the right alloys that can withstand such low temperatures is even tougher.

India made CE-7.5 cryogenic engines which it used successfully for the first time in the GSLV-Mark II rocket in 2014. The CE-7.5 engines, partly based on archaic Russian technology, had a thrust of 75 kN (kilo Newtons). The CE-20 cryogenic engines, used in Monday’s GSLV-Mark III, are not only indigenous but also have a maximum thrust of 200 kN. GSLV-Mark I was powered by Russian-made cryogenic engines.

Long and tough journey

The journey from CE-7.5 to CE-20 has been long and tough for the Indian scientists, and made nearly impossible by US sanctions against India in 1992 and the secrecy that surrounds this technology in countries that possess it on account of its relevance to missile making.

In that context, it is truly remarkable that Indian scientists developed these engines in a relatively shorter period and at a lower cost than developed countries.

India began its work on cryogenic engines in 1982, setting up a small team for the job. But to expedite its space projects, India signed a deal with the Soviet Union in 1991 for supply of two engines and transfer of technology. We even sent a team of scientists to Moscow for training. India picked Russia over the US and France, who quoted higher prices.

But the US scuttled this deal, saying India could use the technology for military purposes and that it violated the 1987 Missile Technological Regime (MTR) norms. In 1993, Russia reneged on the deal. But under a reworked agreement, Russia later supplied seven engines without transferring technology.

Undaunted, ISRO initiated a project in 1994 to make its own engines. They finally developed CE-7.5 in 2009. But the GSLV Mark-II D3 that used these engines to launch 2,220-kilogram GSAT-4 failed in April 2010. The GLSV Mark-II D5 that launched the 2,000-kilogram GSAT-14, powered by the CE-7.5 engines was successful in January 2014. From then on, the engines had a good run. Using them, Mark-II vehicles successfully launched GSAT-6 (2,117 kilograms), INSAT-3DR (2,211 kilograms) and the South Asia satellite (2,230 kilograms) in 2015, 2016 and 2017 respectively.

Work on the CE-20 engines began in 2002. However, they were ready for their first major test only in 2014 and were finally flying-fit on Monday for the maiden developmental flight.

What if satellites weigh more than 4 tonnes?

India’s GSAT-11 satellite weighs 5,700 kilograms and will soon be launched by a foreign launcher, since it’s beyond the capability of GSLV-Mark III.

The standard size of communications satellites is going up to six tonnes, but a good part of the additional weight is primarily meant to increase their lifespan. As things stand today, ISRO is unlikely to come up with yet another rocket to launch satellites heavier than 4,000 kilograms any time soon. Instead, it may give GSLV more thrust, by either adding more power to the cryogenic upper stage, or by turning the lower stages into partly cryogenic or by doing both as and when necessary.

For now, ISRO must be content with the fact that about half the satellites launched in the world in the last decade weigh less than four tonnes. And luckily for ISRO, an average communication satellite’s weight the world over may also come down for two reasons.

One, electronic components are getting smaller and smaller. Two, a switch from chemical fuel to electronic propulsion on board satellites for their in-orbit functions is already making them lighter. Depending on a satellite’s weight and the expected lifespan, its on-board chemical fuel may weigh hundreds of kilograms, but replacing it with electricity, even partially, will lessen the weight.

The GSLV-Mark III will serve India well. The four-tonne satellite is good enough to take care of India and other countries' communication needs for a long time.


Updated Date: Jun 05, 2017 21:39 PM

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