Of INSAT-2E and projects beyond

Print edition : March 27, 1999

Interview with ISRO Chairman K. Kasturirangan.

The year 1999 promises to be a busy year for the Indian Space Research Organisation (ISRO). In May, the indigeniously-built Polar Satellite Launch Vehicle, PSLV-C2 will be launched from Sriharikota, Andhra Pradesh. It will put into orbit the Indian Remote-sensing Satellite, IRS-P4. This will be followed by the launch of the third generation INSAT-3B by Arianespace from Kourou, French Guyana. ISRO will launch its own gigantic Geo-stationary Satellite Launch Vehicle (GSLV), with a Russian cryogenic stage, from Sriharikota by the end of the year or early next year. The GSLV will carry the indigenously built Geostat ionary Satellite, GSAT. But first, in early April, it will be the turn of INSAT-2E.

INSAT-2E is the most advanced multi-purpose satellite built at the ISRO Satellite Centre in Bangalore. It has state-of-the-art payload for telecommunications, television broadcasting and weather forecasting. According to Dr. K. Kasturirangan, ISRO Chairman, it is the heaviest satellite (weighing 2.5 tonnes) built by ISRO. On February 13, it was airlifted to Kourou.

In an hour-long interview given to T.S. Subramanian at ISRO headquarters in Bangalore on March 12, Dr. Kasturirangan (who is also Chairman, Space Commission, and Secretary, Department of Space), spoke of the promise and prospects of India's space programme in the context of the launch of INSAT-2E.

Excerpts from the interview:

How do you assess the progress of the INSAT programme which started with APPLE (Ariane Passenger Payload Experiment), the first experimental telecommunication satellite that India built?

We have come a long way. In the APPLE project we designed and developed a three-axis stabilised satellite for communications, and demonstrated the ability to operate it from a geosynchronous orbit. We mastered the technologies related to this, such as deployment of panels for power generation, design and development of transponders that form the heart of the system, and so on.

Other milestones in satellite communications were SITE (Satellite Instructional Television Experiment) and STEP (Satellite Telecommunica-tions Experiment Project). SITE for the first time showed the efficacy of satellite communications systems for developmental communications. STEP provided a unique opportunity for the use of a satellite system along with a terrestrial network to increase the outreach and capacity of the country's communications network. Both these provided valuable experience and expertise on the applications side. APPLE provided the necessary capability on the communications technology side. So it was a marriage of these capabilities that set off the INSAT programme.

Recognising the need for a system that could meet the requirements in the areas of education, development communication, rural development and information dissemination, we went ahead with the philosophy of procurement in the case of the first generation INSAT series. (India bought INSAT 1A, 1B, 1C and 1D from the United States in the 1980s and early 1990s.)

With the aid of the first generation INSAT series, telecommunications expanded considerably by providing inter-city networks and trunk routes. Today, more than 5,000 of them operate through the Insat system. We also integrated in a novel way the meteorological services into the INSAT series. So it is a novel three-in-one concept that provides satellite television broadcasting, communications and meteorolgical services from a single platform. INSAT-1B and 1D worked well. 1A and 1C did not succeed as well as we expected.

By the end of the first generation of INSAT systems, ISRO had developed its own capability to build the second generation. The second generation had improved capabilities in newer frequencies and an improved radiometer for weather observation. Four of them have been launched. We had one setback in the loss of INSAT-2D. INSAT-2A, 2B and 2C have been fulfilling the objectives set for them. We are now going to launch the final satellite in the second generation series, which is INSAT-2E.

What are the improvements made in INSAT-2E on the basis of the recommendations made by the committee which reviewed the failure of INSAT-2D?

The review committee went into all the details of the problems seen in the orbit of INSAT-2E. It did a lot of ground simulation and analysis of data.

We have provided sufficient isolation to the two power buses (that is, power lines) which are critical to the functioning of the spacecraft. We have put several protection features into the power lines. We have changed the wires that are used to carry high currents. These wires, with specific material characteristics, are less susceptible to radiation damage, brittleness and arcing.

It is said that INSAT-2E is one of the most advanced satellites in terms of technological and electronic software.

At 2.5 tonnes, INSAT-2E is the heaviest satellite we have built. It is the longest - at 18 metres - on end-to-end measurements. We have introduced transponders which are much more powerful. The transponders on 2C and 2D had an outreach from South-East Asia to West Asia. In INSAT-2E, we have transponders which are global in terms of the beam; also zonal beams and national beams. So there are three classes of beams. The global beams cover the whole of Australia on the eastern side to Western Europe on the western side, through South-East Asia, South Asia and West Asia. The zonal beam transponders cover broadcasting capability which covers South-East Asia, the southern regions of China, India and West Asia. Then we have national beam transponders. Totally we will have 17 transponders operating in the normal C-band, the lower extended C-band in 2E.

The other important feature is the meteorological component in which, for the first time, we have introduced a water vapour channel. This will improve the information content for weather modelling and prediction.

For the first time, we are going to fly in INSAT-2E a camera system based on the charge coupled device. This will provide in three bands resolution of the order of 1 km in the visible channel. The previous visible channels in the Very High Resolution Radiometer provided a resolution of 2 km. That is broadly on the payload side.

On the spacecraft side, in view of the larger power requirements - about 2.5 kilowatts - we have introduced gallium arsenide solar cells instead of silicon solar cells. We have put heat pipes so that thermal management is made feasible. For the first time, we have used panels with embedded heat pipes. We have a vastly improved control system design, a new type of processor, a new approach to software realisation, and so on.

Besides, we have introduced a reconfiguration of the power generation and distribution scheme through the isolation of the power buses as called for by the review committee.

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How many transponders of the INSAT-2E are you leasing to INTELSAT? Do you have excess capacity to do this?

Out of 17 transponders, we plan to lease 11 of the 36 megahertz bandwidth each to INTELSAT, which booked them on a bulk lease basis in January 1995. It is not that we have excess capacity. INTELSAT is an inter-governmental consortium and Videsh Sanchar Nigam Limited is represented on its Board of Governors. They operate 22 satellites in order to provide telecommunications and television broadcasting services.

They have a kind of benchmarking for their needs, which is very demanding. So once you provide these kinds of transponders to INTELSAT, you have obviously benchmarked yourself for a certain level of performance. I treat this as an important step from that point of view. In the long run, we should look at the commercial aspects of such satellites and our ability to meet the possible increase in private demands.

There are plans to launch the third generation 3A, 3B, 3C, 3D and 3E. Do you think we will need the transponders in all these satellites?

These requirements are generated on the projections made by the Information and Broadcasting Ministry and the Department of Telecommunications. So far INSAT is used only by government agencies. With privatisation and globalisation, there can be opportunities for private parties to seek INSAT transponders.

Then you have the important factor of ageing of the second generation of the INSAT series. INSAT-1D and 2A are getting phased out. 2B will get phased out by 2000 or 2001. So there is a gradual reduction in capacity.

Putting all these together, we find that by 2002 or so, India will need 130 transponders in these frequencies. The strategy is to distribute them on the various satellites of the third generation.

Why has the INSAT series been plagued by failures? Short-circuits in power buses, leading to the loss of earth lock, seems to be the bane of the series. INSAT-1A's solar sail did not open up and it was affected by power shortage. It lost the earth lock because of unanticipated moon interference. INSAT-1C suffered from a short circuit in one of the power buses and it was abandoned. INSAT-2D suffered from a short circuit in one of its power buses and ultimately it lost the earth lock. Did these happen because they are multi-purpose satellites?

I will not agree with that. We have proved through the long-lasting life of INSAT-1B and 1D, and 2A, 2B and 2C that their lifetime of seven to eight years has been realised in the multi-purpose configuration.

What we are trying to do in a multi-purpose satellite is to put the Very High Resolution Radiometer (VHRR) - the solar panel on the one side, and the sail and the boom on the other - so that the satellite has an asymmetric configuration. If it is purely a communication or broadcasting mission, we can then have two-sided panels as in 2A and 2C. So the deployment of the sail and the boom, and their operation have been satisfactorily established in four satellites.

There are always failure modes because there are certain levels of reliability of components. There are some hiccups in space in terms of electro-magnetic interference or electro-magnetic compatibility. Everytime we encounter such problems, we learn from it and make sure that the problem does not recur. But every complex system has its own level of reliability or unreliability, and it is not related to the multi-purpose character of the system itself.

Why do we prefer Ariane flights for the INSAT series?

We have over the years developed a working relationship with Arianespace. Then the question is subject to cost competitiveness. You have a couple of companies in the world - Lockheed-Martin and Boeing. Lockheed-Martin is also tied up with Khrunichev, so Russia comes into the picture. That leaves us with China - the Great Wall Industries. But they have a higher latitude launch. If you go for Ariane, you get the advantage of near equatorial inclination with very little correction needed. Correspondingly, you have improved fuel availability - even for on-orbit. Besides, the vehicle gives us a lot of confidence.

INSAT-2E will be launched by Ariane 4. It will be a dedicated launch because there will be no co-passenger. We are also working with Arianespace for possible cooperation to market PSLV.

Will it launch IRS type satellites?

No. Right now, there is an agreement which provides for the launch of 100 kg, 150 kg class of satellites which can piggyback on the PSLV with the main mission. Later, the possibilities are not ruled out that we should get a market for the IRS class of satellites for polar orbits or some other type of mission.

PSLV-C2, which is to be launched in May from Sriharikota, will deploy our own Oceansat besides a German satellite and a Korean spacecraft. What are their applications?

The P-4 is the first ocean satellite we are building. Its ocean colour monitor will provide information on ocean biota and phytoplankton distribution. One of the important things related to global weather change studies is the level to which oceans are able to assimilate carbon dioxide. This will be an important instrument, and at 350-metre resolution, it is the best resolution you will get anywhere.

Another instrument is the multi-frequency scanning radiometer which will be used to measure ocean surface temperature, winds and the structure of waves.

The Korean KITSAT (KIT for Korean Institute of Technology) is 107 kg in weight. It is a technological satellite primarily to develop capabilities and prove many systems for micro-miniaturisation and so on. It also carries a small camera for remote-sensing.

The German satellite TUBSAT (TUB for Technological University of Berlin) is for studies related to three-axis attitude control and to qualify different systems for pointing a high-resolution earth observation (payload). It weighs 45 kg.

INSAT 2-E, the most advanced multi-purpose satellite built at the ISRO Satellite Centre in Bangalore, which will be launched in early April.-T.L. PRABHAKAR

IRS took imagery of the damaged office of the Iraqi intelligence during Operation Desert Storm. Does it mean that our imageries will now be in greater demand?

The IRS capability at five metres is the best that is available in the civilian domain. So when these pictures are available, people will have an appreciation of this kind of imaging system. There can certainly be an interest for IRS pictures for developmental applications. For rural connectivity and urban development, these imageries are of use.

Have the U.S. sanctions, in the aftermath of the nuclear tests, hit ISRO?

Sanctions have become a real-life problem for ISRO. We have learnt to live with it, in a sense. If one has to understand it, one has to look at the totality of work that goes on (in ISRO) in terms of indigenising many areas of space requirements such as components and materials. They (the sanctions) make designs more flexible. It is not the problem of producing these materials and components. It is a question of economics. When the requirements are small and one cannot produce them on a scale that is economically viable, one has to depend on outside help.

What is the progress in building cryogenic stages for the Geo-Stationary Satellite Launch Vehicle?

We are in the process of assembling the engines. The first step is the engines. This itself is a very complicated exercise and we also have to develop critical components related to this for the thrust chamber, turbo-pumps and so on. We are working on all these in a parallel manner. The first step in evaluating the design should start this year. But it is going to be a long journey because these are inherently complex systems. I will keep my fingers crossed at this juncture.

Besides South Korea and Germany, has anyone approached Antrix Corporation (the commercial arm of ISRO) for satellite launches?

We have an agreement with a Belgian agency to launch a satellite called Proba. They want it to go up around 2000-2001.

ISRO is going to build a new launch pad at Sriharikota. We will shortly finalise it and announce it. It will cost Rs.300 crores. It will cater to the PSLVs and the GSLVs.

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