“This book gives a glimpse of the author’s own account of this spectacular journey from humble beginnings, the establishment of a unique world class facility that turned out world class earth observation systems to bring ISRO to this enviable position. I am confident the book will appeal to all those who are interested in the evolution of remote sensor technology in India as well as professionals who want to get an insight into the technical complexities in realising a space borne camera system.”
Dr K Kasturirangan, former Chairman ISRO/ Secretary DOS in the Preamble to the book.
“I compliment Dr. Joseph for having put together the historical perspective of developing space based camera system in ISRO and the technical innovations carried out during the realization of the camera system, all in one book. I hope the book will interest a broad range of readers both within and outside the country. Those who were part of the journey will feel a sense of satisfaction and proud of what they could achieve and the younger readers will be inspired and encouraged to be part of this excitement. The book should interest all those who want to know how India has achieved preeminence in space based remote sensing. I wish the book wide readership.”
A.S. Kiran Kumar Chairman ISRO/Secretary DOS, in the foreword to the book
Below front matter is provided. For details refer to the above book.
INDIA’S JOURNEY TOWARDS EXCELLENCE IN BUILDING
EARTH OBSERVATION CAMERAS
Old No. 38, New No. 6
McNichols Road, Chetpet
Chennai – 600 031
Re-Published by Notion Press 2016
Copyright © George Joseph 2016
All Rights Reserved.
This book has been published in good faith that the work of the author is original.All efforts have been taken to make the material error-free. However, the author and the publisher disclaim the responsibility. No part of this book may be used, reproduced in any manner whatsoever without written permission from the author, except in the case of brief quotations embodied in critical articles and reviews.
The Indian Space program was initiated with a vision to use space technology for national development in the thrust areas of communication, navigation, resource survey/management and meteorological applications. Towards meeting these objectives, two major operational systems have been established – the Indian National Satellite (INSAT) for telecommunication, television broadcasting, and meteorological services and the Indian Remote Sensing Satellite (IRS) for monitoring and management of natural resources and Disaster Management Support. India is also establishing a constellation of Indian regional navigation satellite system (IRNSS) to provide accurate position information service. These systems have taken the benefits of space technology to the society at the grassroots level. In addition to the application driven programs, front ranking scientific investigations are being carried out in the fields of astronomy, atmospheric sciences and planetary exploration. Over the years, the space program has become largely self-reliant with capability to design and build satellites for providing space services and to launch them using indigenously designed and developed launch vehicles.
In India, development of satellite platforms for acquisition of remotely sensed data began in late seventies with the Bhaskara mission which had a two-band TV payload for land applications and a Satellite Microwave Radiometer (SAMIR) for oceanographic/atmospheric applications. Since then, considerable progress has been achieved in building complex space platforms with advanced sensors to provide wide range of information available in the electromagnetic spectrum extending from visible to microwave region. India has now one of the largest constellations of civilian earth observation satellites providing information on various sectors such as agriculture, land and water resources, forestry, fisheries, environment, natural disasters, urban planning and infrastructure development, rural development and so on. In this journey ISRO has developed expertise in various technologies.
In the present book Dr. George Joseph discusses one aspect of the space based remote sensing technology namely the imaging system. The book traces the evolution of earth observation cameras in ISRO; how from a humble beginning of a two band framing camera ISRO went on to developing world class imaging system from space and the innovations carried out in the course of development of these sensors. The book also discusses the rational to choose various camera specifications based on the application needs. Dr. Joseph is eminently qualified to write on this subject since the development of electro-optical sensors in ISRO started under his overall guidance. Thanks to great foresight of Dr. George Joseph, ISRO became one of the early adopters of CCD based pushbroom technology, when established earth observation systems were still using opto-mechanical scanners. Use of pushbroom technology paved the way for achieving leadership in providing high resolution imaging in civilian domain in the areas of ocean colour imaging sensor, panchromatic camera for IRS 1C, and CCD payload from geosynchronous platform. I compliment Dr. Joseph for having put together the historical perspective of developing space based camera system in ISRO and the technical innovations carried out during the realization of the camera system, all in one book. I hope the book will interest a broad range of readers both within and outside the country. Those who were part of the journey will feel a sense of satisfaction and proud of what they could achieve and the younger readers will be inspired and encouraged to be part of this excitement. The book should interest all those who want to know how India has achieved preeminence in space based remote sensing. I wish the book wide readership.
A.S. Kiran Kumar
Chairman ISRO/Secretary DOS
History changed on October 4, 1957, when the Soviet Union successfully launched the world’s first artificial satellite Sputnik that marked the start of the space age. Barely five years after this historic event, convinced by the potential of this advanced technology to address the real problems of man and society, India initiated the space program. During the past five decades India has made rapid strides and achieved a pre-eminence position among the space faring nations in developing technology and applying it for the national development in various sectors. One of the areas in which India has excelled is Remote Sensing both in technology and its application. India has a constellation of earth observing (EO) satellites serving both national and inter-national community. The heart of the remote sensing satellite is the imaging sensor. Development of electro-optical sensors in the Indian Space Research Organisation (ISRO) was initiated at the Space Applications Centre (SAC). I had the privilege of leading the team from the very beginning. This book traces the development of the EO cameras and provides insight into the technological innovations and the leadership foresight which placed India at par with the achievement elsewhere in this area.
To have continuity Chapter 1 starts with evolution of the Indian Space Program and traces the initiation and growth of remote sensing activity in India. Chapter 2 narrates initial steps taken in setting up a team for sensor development. In order to appreciate the technical details given in the following chapters Chapter 3 presents an overview of earth observation camera system and importance of some of the terminologies used. Chapter 4 brings forth the evolution of aerial sensor development. Chapter 5 describes the technical issues in designing an imaging system from a spinning satellite and realization of the TV cameras for the first remote sensing satellite of India- Bhaskara, which laid the foundation for space based sensor activities. Chapters 6-8 bring to light the technical issues in the development of observation system for the Indian RemoteSensing Satellites and innovations adopted at various stages of realization of the sensor systems. These chapters also bring out how the Indian remote sensing activity evolved as a self-reliant, application driven program with vital links to the user community. Chapter 9 talks about the evolution of planetary exploration and future possibilities. Chapter 10 illustrates how the data from the IRS satellite is used by the international community. Chapter 11 gives a broad summary and some general observations of the work culture of ISRO and challenges in the development of future earth observation systems. The Bhaskara TV camera failure analysis, which led to the subsequent successful operation, is brought out in Appendix-1. In order not to lose the continuity some of the technical details are given in Appendix-2, under supplementary notes (SN). Readers who want to get a quick glimpse of the subject may skip these notes; however, going through the notes may help the reader to appreciate the technical nuances in realizing the cameras. Appendix-3 gives a list of India’s space based electro-optical earth observation cameras with its main characteristics. In order to facilitate non specialists, Appendix-4 contains glossary of terms of relevance to this book. I have included a few anecdotes/incidents some of which I heard from Prof. Pisharoty during our long wait at the airports to catch flights.
I must make it abundantly clear that the statements as well as observations I have made here of persons/ incidences/organizations are solely my personal views and they do not reflect the official policies or positions of ISRO nor have the endorsement of ISRO as an organization As in any major projects, the success in realizing the earth observation systems discussed here was a team effort; various Centres of ISRO, mainly by the sensor development team at SAC contributed to this endeavor. There are so many of these wonderful colleagues who have contributed to the development of these world class sensors. It is practically impossible to mention each of them by name; however I have named some of the leaders who contributed to this effort during the formative stage of the program. If I have left out some names it is not intentional but inadvertent.
I am grateful to Prof. Yash Pal, the first director of SAC, for inviting me to join SAC and Prof. P. R. Pisharoty for persuading me to contribute to development of remote sensing leaving my basic research at the TataInstitute of Fundamental Research (TIFR), Mumbai. I am indebted to Prof. U. R. Rao, former Chairman ISRO, for his inspirational support during my stay in ISRO.
I am grateful to Mr. A. S. Kiran Kumar, Chairman ISRO, for writing the foreword. Mr. Kiran Kumar played a decisive role in all the technological innovations discussed in this book. I am indebted to Dr. Kasturirangan, former Chairman ISRO, for critically reviewing the manuscript, providing very useful suggestions and writing the preamble. I would also like to express my sincere thanks to Dr. Rangan for his enthusiastic support and encouragement during the course of my career in ISRO. I am thankful to Directors of the Space Applications Centre who extended to me the necessary facilities in the course of preparation for the book. I am thankful to Mr. Padmanabha K Joshi, Coordinator, Vikram Sarabhai Archives, Nehru Foundation for Development, who painstakingly collected and made available to me some of the original documents relating to the early phase of the space program. I am thankful to a number of my colleagues, in particular Dr. R. R. Navalgund, former Director, SAC, Mr. D. R. M. Samudraiaha, former Deputy Director SAC, and Dr. J. V. Thomas, Program Manager, ISRO HQ, and Mr. Adalka Dheeraj, SAC who have critically gone through the manuscript and made very useful suggestions. I sincerely acknowledge their contributions. I am thankful to Mr. Devan A Raval for providing secretarial assistance during the preparation of the manuscript.
I am grateful to my wife Mercy for her encouragement and moral support without which the book would not have been completed.
(*Former Chairman ISRO/Secretary DOS.)
Soon after independence, the Indian political leadership recognized that the country needs, a variety of inputs encompassing social, economic, educational, industrial, agricultural, infrastructural among others, to take India on the path of speedy progress and development. In this context, the crucial role of science and technology was realized to be an important element as a part of early planning. Of the many initiatives to bring the benefits of science and technology to the country, the space program, which is the foresight of a great visionary and physicist Vikram Sarabhai, stands as a shining example of taking technology to solve the real problems facing the nation. From a humble beginning of launching a sounding rocket in 1963 from Thumba (a village in south India) for atmospheric studies, the Indian Space Research Organization (ISRO) has today established operational space systems and services, attained selfreliance in development of indigenous technology and accomplished exemplary feats in space exploration, yet ensured that benefit of space reaches the common man. The major uses of satellites can be broadly classified into three categories: (1) to look at the heavenly bodies – stars and galaxies – to understand their characteristics, which will probably give us a better understanding of the evolution of the universe and our own solar system-the space science; (2) act as a relay ‘tower’ in the sky to receive and retransmit the electromagnetic radiation-space communication, navigation etc; (3) acting as an ‘eye in the sky’ to look at the Earth to get a synoptic view of the Earth’s features, to derive information about the Earth and its environment, weather system and various resources – both natural and manmade – for its optimum management – known as Remote Sensing.
The Indian Space programme evolved through three major phases. The first phase related to initiation of activities with the objective of proof-of-concept evaluation, followed by the experimental phase ofrealizing end-to-end capability demonstration and leading finally to the operational phase for providing regular services. Since the present book deals with remote sensing I shall elucidate these points with respect to space based earth observation system. In the initiation phase, one of the primary tasks was evaluation of the efficacy of space systems as either alternative to conventional terrestrial systems or to look at them as complementary or supplementary to the conventional approaches, particularly in the area of resource management. Landsat, launched by USA in 1972 provided a unique opportunity to scientists for testing out the utility of a satellite based earth observation system for obtaining timely, accurate and precise information of earth resources. India after establishing its own Landsat receiving station started receiving regularly remote sensing imagery over the country. The initial years were more of a research exercise at using spacebased imagery to establish its feasibility for natural resources inventory. The exercise of establishing ground systems, integrating space based data with conventional aerial and ground based data and working closely with user community, provided several crucial insights for planning the future operational remote sensing systems. During this period several ground and aerial instruments were developed which facilitated to understand the nuances of sensor development and data product generation. The experimental phase was identified with a strategy to realize systems where the potential of its use at the national level had already been clearly demonstrated in the proof of concept phase. The next step was to create an end-to-end capability in the design, development and in-orbit management of space systems together with the associated ground systems needed for the users. These were systems with limited capability, realized within stringent cost and time controls. In the case of remote sensing, the experimental satellites Bhaskara-1 and Bhaskara-2 were the pioneering steps in this direction. The Bhaskara mission, even with 1 km resolution, enabled developing the capability to image from space, transmitting and processing the image information on the ground, disseminating the data products to the users and getting their response. This phase additionally facilitated competence building at the core level, helped in the detailed evaluation of issues for scaling the effort to the national level and set the rules relating to the overall practices in system engineering. The overall demonstration of the systemic approach in this phase paved the way forthe country to create national systems at a much larger scale with bigger and more sustained investments.
Building technological competence is a key factor to provide sustained operational services to the country. Starting from basic developments, ISRO has achieved a level of technology, which is world class. The Indian Remote Sensing program is an excellent example of realizing this level of world leadership. With the inputs from the initiation and experimental phases as elaborated earlier, we were in a position to take the next step, to achieve a quantum jump in terms of establishing a space based Earth Observation system-the Indian Remote Sensing Satellite (IRS) – for natural resources management and environmental protection. The heart of such a system is the imaging camera. The migration from a two band 1km resolution camera to 36 meter four band camera was a big leap in technology. Innovative approach is crucial to achieve such a development which is the theme of this book. In contrast to expensive, heavy spacecraft with complex moving mechanisms adopted by the world for earth observations, the first generation IRS was designed with many innovations. A pioneering, step of using solid-state detector (CCD) arrays ensured simplified designs, besides triggering development of novel optical systems and an original approach to low weight spacecraft. This gave better-cost efficiency, improved turnaround time for manufacture, a high degree of reliability, yet a performance comparable to best systems in the world. This choice of solidstate detectors also offered better growth potential. The use of CCD devices for imaging which did not have any flight pedigree at that time might have seen as a risky step but it clearly demonstrated the technological foresight. In fact later CCD based imaging system became a world trend in imaging from space. With the launch of IRS1C in 1995, ISRO could provide the highest spatial resolution imaging system to the global remote sensing user community. The launch of follow-on satellites – Resourcesat – provide a unique combination of multi resolution and multi swath capability making them the most versatile earth observation platform for earth resources monitoring. The Oceansat series provide data specific to extracting parameters of the ocean. The launch of the RISAT carrying C band SAR with multimode operation capability has added to the fleet of Indian Earth observation system. In addition to these low earth orbiting satellites India also have imaging system from Geostationary orbit. In view of the excellent quality of data these imaging systems provide, they have become part of global source for remote sensing data.
The development of the electro-optical sensors in ISRO was initiated and nurtured under the overall guidance of Dr. George Joseph. The name of Dr. George Joseph is synonymous with the development of electrooptical systems for space missions in this country. I came in contact with Dr. George Joseph during my student days when we both used to meet at the Hyderabad balloon facility for flying our respective instruments, mine for looking at diffuse cosmic X-rays from space and Dr. George Joseph for studying high energy cosmic rays. Our association became closer when I was made the scientific coordinator for the three scientific experiments flown on India’s first satellite – Aryabhata. Dr. George Joseph and his colleagues from Tata Institute of Fundamental Research designed and developed a payload for detecting neutrons and gamma rays from the sun- a unique instrument with complex detection systems using inorganic and organic scintillators. George brought to bear with his extraordinary insight into developing complex instruments for radiation detection and analysis. Soon after Aryabhata, Dr. George Joseph was selected by the then Director of Space Application Centre Prof. Yash Pal to initiate work on electro-optical systems for remote sensing with its immediate application for ground based and air borne studies with a futuristic vision of space borne observations. The pioneering effort of Dr. George Joseph together with his colleagues, in the area of electro-optical systems lead to the definition of the first camera system for space in Bhaskara – India’s first earth observational satellite. The choice of a suitable camera for this spinning satellite was no easy task. I had the privilege of seeing Dr. George Joseph going through various options meticulously and ultimately making the necessary choice that led to the slow scan vidicon system onboard Bhaskara I and its successor Bhaskara II. When there was an initial hiccup of corona discharge in this pay load, on Bhaskara I, which was using high voltage systems the analysis, interpretation and possible recovery from the anomaly was all spear headed by George Joseph along with his very illustrious colleague Mr. Kiran Kumar, who is now the Chairman of ISRO. I watched with great admiration their efforts to understand the problem from the perspective of physics, material behavior and its incompatibilities in an environment of vacuum and temperature variations, strategy for simulation and modeling all of which led to the ultimate recovery of one of the cameras after 6 months, an extraordinary feat! Dr. George Joseph’s next task was to develop a sophisticated camera system for the IRS. Here again the task was to catch up with the performance of the best of the contemporary systems which was the preserve of only two western countries. He came out with interesting innovation in the choice of the detector i.e. CCD, optics, signal and image processing, feature analysis and identification besides interesting calibration techniques. In the very first of the IRS series, Dr. George Joseph and his team achieved a performance level of the payload to the contemporary standard achieved by the two countries at that time. Since then, he went on to design and develop camera systems with more advanced characteristics for IRS 1C and 1 D, ocean color monitors for OCEANSAT, camera for a high resolution satellite called TES(Technology Experimental Satellite), satellite for cartographic applications introducing stereoscopic capabilities etc..
It is one of the most remarkable feats in the annals of remote sensing that in just two decades Dr. George Joseph put India on the world map where it came to occupy a pre-eminent position. The conceptualization, installation and operationalization of a variety of complex infrastructure for the cameras needed for their design and evaluation, development and testing including calibration and the unique test setup for the optics with demands on extraordinary precision and accuracy ultimately left a legacy which India can rightfully boast off today.
The book also brings out the management aspects and the role played by leadership which make ISRO stand out as a successful high-tech organisation. This book gives a glimpse of the author’s own account of this spectacular journey from humble beginnings, the establishment of a unique world class facility that turned out world class earth observation systems to bring ISRO to this enviable position. I am confident the book will appeal to all those who are interested in the evolution of remote sensor technology in India as well as professionals who want to get an insight into, the technical complexities in realizing a space borne camera system.