K Radhakrishnan | Flight stage tests for GSLV this time next year

K Radhakrishnan | Flight stage tests for GSLV this time next year
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First Published: Fri, Jul 08 2011. 09 38 PM IST

Flight philosophy: Radhakrishnan says Isro’s main endeavour is to get as many parameters checked in static ground tests. Photo Aniruddha Chowdhury/Mint
Flight philosophy: Radhakrishnan says Isro’s main endeavour is to get as many parameters checked in static ground tests. Photo Aniruddha Chowdhury/Mint
Updated: Fri, Jul 08 2011. 09 38 PM IST
Bangalore: Indian Space Research Organisation (Isro) chairman K. Radhakrishnan spoke in an interview about the country’s space programme, cryogenic engines, the Chandrayaan-2 mission and changes since the Devas-Antrix controversy.
Next week you’re launching a satellite on the Polar Satellite Launch Vehicle (PSLV). When can we next expect a launch aboard a Geosynchronous Satellite Launch Vehicle (GSLV) with our own cryogenic engine, given that previous attempts have resulted in failure?
Flight philosophy: Radhakrishnan says Isro’s main endeavour is to get as many parameters checked in static ground tests. Photo Aniruddha Chowdhury/Mint
Next year this time, we will be conducting flight stage tests (a preliminary to the launch). Flight stage readiness is one thing, but before it is inducted into a launch, we have to ensure that all the ground tests are okay. Also, when we launched the satellite in December, we used a very costly satellite (GSAT-5P)— almost Rs 150 crore—with lots of features. This time we’ll go for a cheaper satellite (GSAT-14), something that doesn’t require much effort. At best, we’ll be able to put in some transponders in the C-band. If the vehicle underperforms, it won’t be much of a loss. If this one goes well, we will launch the GSAT-6, the “famous” one (that was embroiled in the Isro-Devas row). This, too, will go only on an indigenously developed cryogenic engine. After that it will be Chandrayaan-2 (scheduled for around 2013). There are also changes in the whole GSLV vehicle per se. From 1.5-tonne payloads, we’ve now reached about 2.2-tonne payloads. The biggest change effected is the size of the heat shield [a protective sheath that also determines the size of communication satellites to be put into orbit] and the materials we use for it. We’ve gone from 3.5m heat shields to 4m, and use composites [such as plastic fibre] instead of metal. For GSLV Mark-3, we may have to use 5m shields.
Why is developing a GSLV so difficult?
We’ve bought seven cryogenic engines from Russia, of which we’ve used six. The results coming out of GSLV have been mixed. Sometimes unforeseen obstacles don’t emerge until it’s actually launched. For instance, when we tried to launch last April using (an) indigenous cryogenic engine, all the preliminary stages were fine and our cryogenic engine ignited—and ignition in vacuum is a difficult thing. But after a few seconds, it stopped. For it to keep going, another device called a two-steering engine (or turbo pumps, which keep the launcher steady) ought to ignite, too. This will ignite only if hydrogen and oxygen are present in exact amounts. When we looked into it, there are several possible explanations as to why the turbo pumps stopped: There are three bearings for these turbo pumps; the bearings must rotate without being (distorted) out of shape by the liquid hydrogen fuel it is submerged into. It could also be that the turbo pumps were blown out of shape. There are several things that can go wrong, and each time we have to test from scratch and develop new solutions. While all these have been looked into, we have to undertake a full ground test, before we can be sure that this will work in flight. Hopefully, this flight stage should be ready for testing in March 2012.
So what about the seventh cryogenic engine from Russia? There were reports that both Isro and Russia disagreed on technical reasons for the failure of the most recent GSLV mission in December.
The last two engines (the sixth and seventh) have greater thrust than previous engines. They was supplied in 2004 and 2005, and stored in specified conditions. So the reason for the failure (in December) was the inadvertent snapping of the connectors, well before time [connectors are critical for controlling the vehicle]. This happened because the shroud gave away (the shroud is a casing that separates the liquid and solid stages of the launch cover). It’s a cover that sits on (the) bottom of the cryogenic stage. Now, why did the shroud go? Was it the 4m heat shield? We then realized that it was the inherent vulnerability of the shroud. The shroud was at the bottom of the cryogenic stage. There were 10 connectors in two stages, and both gave way. Initially, the Russians said it was our 4m shield that was responsible. We put both our analyses, and finally the Russians also came around. We then decided that the seventh engine has to be inspected, too. We did it and found that they weren’t made in the dimensions specified to in the document. There are lots of shortcomings, and the Russians admitted it. Now, the point is that this has to be corrected before it can be used for launch and would require a detailed inspection by them.
Does it mean all major missions till Chandrayaan-2 will only use indigenous engines? Since the Russian engine has to be examined, will Chandrayaan-2 be delayed?
Yes, it has to be tested on indigenous cryogenic engines, and we’ll only use our engines for future launches, but that is not why there will be a delay. Historically, the Chandrayaan missions are a joint Indo-Soviet mission. The agreement was that the lander [that will descend on the moon] and the (lunar) rover (a robot vehicle) would be provided by the Russians. We wanted to put a smaller rover; it’s something new that we are developing. However, in Russia there was a rethink. They decided they’ll only develop the lander and some instruments related to it. That means India would have to make a bigger rover, a decision taken almost a year ago. There are also preliminary design reviews to be undertaken this year to select which instruments are to be carried onboard the mission. So it’s not only GSLV (engines); there are other reasons for the delay.
Relative to the number of failed satellite launches, does Isro have greater success compared with international agencies?
There are two things: on-ground tests and eventual flight tests. Each country has its own philosophy. Russia is very conservative; America less so. I can’t really say where India is on that scale, but we have our own approach, too, that we have debated since our space programme began. Our main endeavour is to get as many parameters tested in static (ground) tests, because each of these tests involves a lot of time, money and effort. Russia also does a lot of ground tests. That said, however, between 1957 (when the so-called space age began) and 2010, there have totally been 320 failures across nations, and there’s no constant success-failure ratio (across nations).
What changes have taken place at Isro since the Devas spectrum controversy broke out? Will there be changes in the way transponders and related spectrum are leased out to private bodies?
Several institutional mechanisms have been put in place. We’re getting a new chairman for Antrix and there’s going to be a new board that will interface between Isro and Antrix. We’re also putting up the satellite policy online for perusal of all. There’s in general going to be greater transparency, though I must add that we weren’t really non-transparent in the first place.
But the biggest fallout of the controversy was the way in which spectrum was allotted to companies. And what happens to the technology itself (that involved multimedia broadcasting via satellites and phones) that was to be tested aboard GSAT-6?
Sure, there’s been a change in the manner in which spectrum is looked at. It’s a demand-supply problem. Initially, there were very few requests for leasing transponders by private operators, and now there’s much greater demand. Therefore, there will be a change in the way these transponders will be managed. The technology will not suffer. We’ve already said that at least for now, it will be directed towards societal and strategic uses, rather than entertainment.
jacob.k@livemint.com
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First Published: Fri, Jul 08 2011. 09 38 PM IST