'Launch established India's PSLVcapability'

Published : Oct 18, 1997 00:00 IST

Interview with Dr. K. Kasturirangan, ISRO Chairman.

Dr. K. Kasturirangan, Chairman, Indian Space Research Organisation, was the centre of attention of the country on September 29 when the Polar Satellite Launch Vehicle (PSLV C-1) lifted off from Sriharikota and deployed a 1,200-kg Indian Remote-sensing Satellite (IRS-1D) into orbit 19 minutes later. There was much rejoicing over the success of the mission; the general jubilation was later slightly tempered by the news that the satellite had been ejected into a lower orbit than planned. However, as Dr. Kasturirangan told T. S. Subramanian in Chennai on September 30, from the "first-cut analysis" of the results, the capability of the PSLV-C1 to take a 1,200-kg satellite has been established. The ISRO Chairman spoke about what led to the satellite being injected into a lower orbit. There was "some unexpected gas leak" in the fourth stage of the rocket, which could have reduced the overall thrust from that phase and the satellite was injected into orbit "at a little less than the required velocity".

About the string of successes that the ISRO has achieved, especially in the PSLV flights after he took over as Chairman, Dr. Kasturirangan was modest. He said, "Every time we score a success, our responsibility to ensure that we keep up that trend is greater than before."

Excerpts from the interview:

How do you assess the success of the latest PSLV flight?

We wanted to evaluate the vehicle system and its ability to take a 1,200-kg satellite into orbit. To the extent that we have been able to do a first-cut analysis of the results, it looks to us that the capability has been established. That is the most important feature of our assessment of the flight. It is a quantum jump from 950 kg to 1,200 kg. There is nearly a 250-kg improvement in the payload capability of the vehicle. (The last PSLV flight in March 1996 deployed a 922-kg remote-sensing satellite into orbit.)

You call this IRS-1D an operational satellite. But from a layperson's point of view, the last two remote-sensing satellites deployed from SHAR in 1994 and 1996 were also operational spacecraft in the sense that they beamed down remote-sensing imageries, which are being put to use. Why do you call this alone an operational satellite?

This is an operational satellite because this satellite is designed as part of the IRS series, starting from IRS-1A, with specific improvements for land applications. In that context, it is the fourth in the series after IRS-1A, 1B and 1C. All of them have established application capabilities in a variety of areas of earth resources which include forestry, hydrology, land use and land planning, urban development, rural development and so on. It is in this context that one has to make a distinction between an operational satellite and an experimental satellite. Experimental satellites carry payloads for establishing new directions in applications through a research and development programme. The P2 and P3 (satellites launched by the PSLVs in 1994 and 1996) belong to the experimental class, whereas IRS-1A, 1B, 1C and 1D belong to the operational class.

There are reports that the IRS-1D deployed on September 29 reached a lower orbit than the planned one. What kind of disturbances in the fourth stage of the rocket led to the deployment of the satellite into a lower orbit?

We have not identified the reason for this. But it appears that in the fourth stage, there was some unexpected gas leak which could have reduced the overall thrust from that phase, resulting in the satellite getting a velocity a little less than the velocity meant for the mission. In terms of numbers, it translates to an apogee of 817 km but with a perigee nearer 300 km. The inclination is what we had envisaged, that is, 98.7 degrees. We have to give an additional velocity of 120 metres a second. We are examining how the on-board fuel from the control systems of the satellite can be used to realise an orbit that would enable us to meet the objectives of the mission.

Did the helium gas in the bottles made of kelvar fibre leak in the fourth stage? In the earlier PSLV flights, these gas bottles were made of titanium.

It does not appear to be so. There was some leak in one of the control components, which we are not very clear about. We will do some simulations to identify the component that could have caused this anomalous behaviour.

Will the satellite's life span be reduced?

We have to look at the strategy for the realisation of the orbit and then see how an optimal approach to the utilisation of the fuel can be evolved. It is premature to attempt to state the full implications.

In the press conference at Sriharikota on September 26, you said the United States had agreed to cooperate with ISRO in certain areas. What are these areas?

A dialogue is on between ISRO and NASA (National Aeronautics and Space Administration of the U.S.) on future cooperation. We hope that a memorandum of understanding can be signed in the near future. It is premature for me to say anything with regard to the areas of the cooperation.

You also said in the press conference that the U.S. had not imposed any curbs on ISRO. But a couple of years, the U.S. did "blacklist" ISRO. If my memory is right, the U.S. did embargo the export of integrated circuits to ISRO.

Two years back, there was the problem of getting the technology transfer on the cryogenic engine. In that connection, there was an embargo.

What is the progress achieved so far in the development of the cryogenic engine?

Indigenous effort has led to the completion of the design of the engine. Right now, metal cutting is in progress. If that goes well, we will be able to proceed with the assembly of an engine by the end of this year. By the early part of the next year, we could even attempt a very, very preliminary test of this first engine. We say "very, very preliminary" because it is just to get a feel of this piece of test engine.

Will the next five remote-sensing satellites to be launched from SHAR be used mostly for marine studies? The IRS satellites are already being used to locate plankton and schools of fish in the sea.

Of the five satellites, one will be for ocean-related applications, primarily for spotting ocean biota. The next one will be a replacement for - a kind of successor to - IRS-1C and 1D operational satellites. The third one will carry improved resolution cameras for cartographic applications. The other ones will include more advanced ocean applications and climatological studies, using active microwave sensors such as scatterometers and altimeters.

What will be the payload of the 100-kg South Korean satellite that will ride piggyback on the IRS-P4 satellite to be launched from Sriharikota next year?

It will apparently have a remote-sensing payload with a charge coupled device camera. This is a three-band camera. It will take images in three colours. There could be a few auxiliary payloads. But the basic mission is the camera mission for remote-sensing.

Is there any plan to fly ISRO scientists on board the U.S. space shuttle?

As of now, we do not have any plans for flying our own astronauts aboard the shuttle. But we are looking into how we can use facilities like space stations in future for specific experiments that we conduct. Such studies would continue and if there is any specific need, we could always consider doing those experiments, notwithstanding whether we fly our astronauts or not.

How do you feel about the string of successes that you have achieved?

Space is a very tricky kind of affair. Even when you score successes, you will have to keep in mind that things can be different. Every mission has to be treated as a unique one. And every time we score a success, our responsibility to ensure that we keep up that trend is greater than before. All I can say at this stage is that the teams in ISRO have given their best and that they will not rest on their laurels.

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