INSAT-2E and projects beyond
Interview with ISRO Chairman K. Kasturirangan
appeared in Frontline, March 27 - April 9, 1999
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 Geostationary Satellite, GSAT.
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.
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.
 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.
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. |
