News

ISRO’s ‘dirty fuel’ dilemma

M Ramesh Chennai | Updated on July 21, 2019 Published on July 21, 2019

A security guard stands behind the logo of Indian Space Research Organisation (ISRO) at its headquarters in Bengaluru.   -  Reuters

For ISRO, the key challenge is to break free from the philosophy that is often expressed in this American aphorism: ‘If it ain’t broke, don’t fix it’.

Perhaps nobody knows better than ISRO that legacy issues are hard to shake off. Take, for instance, the fuel that will power the core (or the middle unit of the lower part) of the GSLV Mk-III, the rocket that will be used in the Chandrayaan-2 mission on Monday.

There are two chemicals at play — UDMH (Unsymmetrical Di-Methyl Hydrazine), which is the fuel, and Nitrogen tetroxide, the oxidiser. This is called a “dirty combination”. UDMH is highly toxic and corrosive if it comes into contact with the oxidiser, an explosion will result.

Elsewhere in the world, space programmes have moved to a cleaner and greener fuel — liquid methane or kerosene.

Experts point out that it is not that ISRO does not know how to shift to these better fuels — only it can’t. Shifting to liquid methane would mean bringing in another cryogenic engine, because any liquefied gas would need to be kept in extremely low temperatures to stay liquefied.

ISRO can use kerosene as the fuel — it can be kept at room temperature — and liquid oxygen as the oxidiser. Indeed, that is the semi-cryogenic engine the space agency has been working on for years.

For now, ISRO is stuck with the dirty fuel because it carries the burden of its legacy. The PSLV, a trusted workhorse, and the GSLV are working fine with the dirty fuel, so why change it?

Legacy is also pretty much the reason why ISRO is still not ready with a semi-cryogenic engine, which could have used cleaner fuels. Having got seven cryogenic engines from Russian, ISRO had no option but to go into developing similar fully cryogenic engines to get the GSLVs going.

Otherwise, it would have developed the simpler semi-cryogenic engine first, and gone fully cryogenic later. In a semi-cryo, the fuel is at normal temperatures, only the oxidiser (liquid oxygen) has to be kept extremely cold. In a full cryo, both the fuel and the oxidiser need to be ultra cold. The GSLV Mk III’s cryogenic engine will have liquid hydrogen (fuel) at -250 degrees C and liquid oxygen at -150 degrees C.

Like a student attempting a more difficult question first in an examination, ISRO has chosen to develop the cryogenic engine first. This should make it easier for it to develop the semi-cryo,. A new engine essentially means a different rocket. Straight-jacketed with a tight schedule of launches, ISRO, with its limited bandwidth, has little headroom to try out a new rocket. Hence, the semi-cryo has remained a low priority even though a rocket with a semi-cryo in the lower stage and a full cryo in the upper would be far more powerful.

If bringing in a different ‘model’ or rocket is difficult, what to say of developing an entirely new family of rockets?

World-over, research is on into air-breathing rockets, which have only the fuel and take oxygen from the atmosphere. ISRO, too, has the ‘scramjet’ technology on its development sheet; when it flight-tested a scramjet engine in August 2016, it was only the fourth country to do so. But incorporating it into a rocket would be to build an entirely new launch vehicle.

That is difficult when the existing rockets, regardless of their dirty fuel and lower power, are working well — that is exactly the problem.

Published on July 21, 2019

A letter from the Editor


Dear Readers,

The coronavirus crisis has changed the world completely in the last few months. All of us have been locked into our homes, economic activity has come to a near standstill. Everyone has been impacted.

Including your favourite business and financial newspaper. Our printing and distribution chains have been severely disrupted across the country, leaving readers without access to newspapers. Newspaper delivery agents have also been unable to service their customers because of multiple restrictions.

In these difficult times, we, at BusinessLine have been working continuously every day so that you are informed about all the developments – whether on the pandemic, on policy responses, or the impact on the world of business and finance. Our team has been working round the clock to keep track of developments so that you – the reader – gets accurate information and actionable insights so that you can protect your jobs, businesses, finances and investments.

We are trying our best to ensure the newspaper reaches your hands every day. We have also ensured that even if your paper is not delivered, you can access BusinessLine in the e-paper format – just as it appears in print. Our website and apps too, are updated every minute, so that you can access the information you want anywhere, anytime.

But all this comes at a heavy cost. As you are aware, the lockdowns have wiped out almost all our entire revenue stream. Sustaining our quality journalism has become extremely challenging. That we have managed so far is thanks to your support. I thank all our subscribers – print and digital – for your support.

I appeal to all or readers to help us navigate these challenging times and help sustain one of the truly independent and credible voices in the world of Indian journalism. Doing so is easy. You can help us enormously simply by subscribing to our digital or e-paper editions. We offer several affordable subscription plans for our website, which includes Portfolio, our investment advisory section that offers rich investment advice from our highly qualified, in-house Research Bureau, the only such team in the Indian newspaper industry.

A little help from you can make a huge difference to the cause of quality journalism!

Support Quality Journalism
This article is closed for comments.
Please Email the Editor
You have read 1 out of 3 free articles for this week. For full access, please subscribe and get unlimited access to all sections.