Prof.Satish Dhawan Commemoration Lecture

“If you do not have a mission, no problem will occur, but if you do have a mission or task definitely problems of varying magnitudes will crop up. But problems should not become the master of the individuals, individuals should become the master of the problem, defeat it and succeed.” -Prof. Satish Dhawan Prof. Satish Dhawan Commemoration Lecture Birth Centenary Celebrations (1920-2020) International Webinar Organised by

PREFACE At various times in his career Satish Dhawan had been a teacher, research scientist, engineer, technologist, manager, leader and adviser - sometimes many of these at the same time. And to everything he did, he brought dedication, breadth of vision, meticulousness and humanity, which combined with his remarkable scientific and technological abilities, transformed every single organisation he worked for and lead, and made it achieve what it had often not thought itself capable of. There were two outstanding features of Dhawan’s philosophy in research. first, it was carried out at low cost, with ingenious development or adaptation of whatever materials, skills and instrumentation were available at the time; second, the basic research areas investigated in his laboratories were all inspired in some way by the problems faced by the newly-born aircraft industry of the country. Dhawan constantly sought to promote the development of this industry at the higher levels of policy and management. Dhawan’s visionary leadership as Director of the Indian Institute of Science, and as Head of the Indian Space Programme has been most noteworthy in the histories of these two institutions. Srinivas Bhogle has provided a life-sketch of Dhawan. Satish Dhawan was an extraordinary teacher. His guidance and leadership have made many of his students prominent leaders in science, technology and academia. Roddam Narasimha, one of the most successful of his students, pays tributes to and recounts his association with Dhawan in the article, “Doing Little Science with Dhawan”. The importance of Dhawan can be gauged by the fact that stalwarts like Kasturirangan and President A P J Abdul Kalam have written about him in this issue.

Selected Articles on Prof. Satish Dhawan re-printed with permission from the Indian Academy of Sciences Publication ‘Resonance’ Vol. 8, No. 10, Oct - 2003 By Institution of Engineers (India) Karnataka State Centre Dr. Ambedkar Veedhi, Bangalore - 560 001 Satish Dhawan Commemoration Lectures are organised with support from ISRO

Peof. Satish Dhawan Commemoration Lecture CONTENTS 4 Satish Dhawan By Srinivas Bhogle 6 Dhawan and the Transformation of the Indian Institute of Science By R. Narasimha 8 Doing Little Science with Dhawan By Roddam Narasimha 16 About Prof. Satish Dhawan By K. Kasturirangan 23 Bird Flight and Satish Dhawan : Some Thoughts By K. R. Y. Simha 31 Satish Dhawan - Creative Teacher By A P J Abdul Kalam 38 How Birds Fly By S. P. Govinda Raju 40 Launching the First Indian Satellite Courtesy : ISRO 44 Remembering Satish Dhawan By Hans Liepmann 3

Peof. Satish Dhawan Commemoration Lecture Satish Dhawan In the mid-1950’s, Satish Dhawan was a handsome Dhawan proved to be an exceptionally successful and dashing young professor at the Department of and durable Director (he was director till 1981) and Aeronautical Engineering in the Indian Institute of largely responsible for making IISc the Science (IISc). He drove a trendy sports car, wore a “multifaceted institution of excellence in higher red shirt and a broad smile [1], and built India’s first science education and research that it is today” [4]. supersonic wind tunnels. Earlier, in 1947-51, he He also managed to find the time to continue his was a researcher at Guggenheim Lab (GALCIT) of work in aeronautics - although it would seem that the California Institute of Technology (Caltech) meaningful technology, rather than papers in who toggled between aeronautics and Shakespeare scientific journals, was now his real love. In fact, and even managed to defeat his PhD supervisor Dhawan;s R&D philosophy always stressed on low (Hans Liepmann) at ping-pong (by being “a crafty cost (“ingenuity, not big money”) and industrial or Asiatic” [2]). social relevance. Dhawan went to Caltech with degrees in science, Dhawan was spending a sabbatical year at Caltech engineering and English Literature. His doctoral in 1971-72 when he suddenly received a call from work at Caltech, to directly measure skin friction, the Prime Minister’s Office asking him to take over was widely hailed. His work with Anatol Roshko, as th Head of India’s space programme following on the design and construction of an ingenious Vikram Sarabhai’s unexpected and shocking death. flexible nozzle for research in supersonci flows, Dhawan clearly didn’t enjoy the interruption and was equally inspired (Lipmann describes it as “an put conditions that must have really angered New example of ingenuity substituting large amounts of Delhi’s bureaucrats: “I will continue to be Director, grant money”). Dhawan also won many friends at IISc and I will only run the Department of Space Caltech with his amiable disposition and charming from Bangalore”, he insisted. Indira Gandhi - she manners. S R Valluri, who was one of Dhawan’s was a shrewd lady! - agreed to all these conditions many friends during 1949-51, recalls how his immediately. “I couldn’t refuse the PM after that”, GALCIT colleagues refused to erase Dhawan’s Dhawan told Valluri as he returned to India to take blackboard scribbles even after Dhawan left up this new challenge. GALCIT [3]. Dhawan’s leadership of India’s space programme At IISc, Dhawan came like a whiff of fresh air. His would probably be rated as his finest contribution to youth, freshness and californian informality the nation. President A P J Abdul Kalam [5] is fond “captivated students and colleagues” [1]. Dhawan of recounting how Dhawan converted Sarabhai’s made more friends and influenced a wide cross- ‘vision’ into an outstanding national ‘mission’. The section of people. He also started becoming a President has another heart-warming story about natural mentor to his younger colleagues (notably how Dhawan acepted all the blame for the SLV-3's Roddam Narasimha) and showed unusual maturity first failure (“We have tumbled, but not fallen flat”, in judging both scientific and human problems Dhawan re-assured him after the first setback) but (something that Liepmann had already noted in gave him all the credit of SLV-3's subsequent Caltech). It therefore came as no surprise when he success. became Director, IISc in 1962 at the age of 42. 4

Peof. Satish Dhawan Commemoration Lecture But this really is what Satish Dhawan was all about. development programme, NAL was like a He was a magnanimous and towering leader, and “beautifully decked up bride with nowhere to go”). one of India’s greatest sons. While Dhawan did get Dhawan would have been delighted with NAL’s his share of acclaim and awards (he was awarded progress on the SARAS programme although he the Padma Vibhushan in 1981 and elected to the US would have felt uncomfortable when told that the National Academy of Engineering), I believe that first aircraft was to be named after him (VT-XSD). not enough Indians appreciate the true import of Dhawan’s contributions. Dhawan of course didn’t Dhawan loved birds. He once wrote: “Whenever care about all this. When he received another award my work related to the country’s space programme in his last years, he asked: “What have I done to became a little taxing, I went to see the birds of deserve this honour?”. SHAR – and came back feeling happy and invigorated”. In the late 1980’s, Dhawan delivered Dhawan was a humanist to the core. He held the a series of remarkable lectures on bird flight; in fact, firm view that science and technology must the only authoritative monograph that Dhawan ever ultimately serve the country and its people. found time to write was about bird flight. I had the Dhawan was also perhaps India’s first champion of pleasure of assisting him in the publication of this numerical weather prediction. Liepmann writes monograph and found him to be a very charming that Dhawan often talked about how “accurate and uncomplicated gentleman. When I asked him, weather prediction could improve India’s economy in all earnestness, what typeface and design scheme decisively”. Expensive or esoteric R&D I must use, he told me: “Just choose what you think programmes, on the other hand, didn’t amuse is right, but make sure that there’s a photograph of Dhawan too much; I remember an angry outburst – SalimAli somewhere. He was a great Indian”. he could get quite angry sometimes – at National Aerospace Laboratories (NAL) when he asked Satish Dhawan, another truly great Indian, passed what was the use of technology if it didn’t serve the away on 3 January 2002, at the age of 81. common man. Dhawan was also the “widely accepted moral and social conscience of the Suggested Reading scientific community” [1]. Indeed, for many, the ultimate question to ask before commencing any [1] Roddam Narasimha, Prof Satish Dhawan, http:// new project or endeavour was: “Would Dhawan www.iisc.ernet.in/nias/sdhawan.htm approve?” [3]. [2] Hans Liepmann, Remembering Satish Dhawan, h t t p : / / p r. c a l t e c h . e d u / p e r i o d i c a l s / E a n d S / a r t i c l e s / After retirement, Dhawan became a gracious and LXV4/obituaries.html affectionate elder with a special fondness for NAL. [3] S R Valluri, Would Satish approve? in Satish Dhawan: A He had worked with NAL teams during the Avro cherished association with NAL. March 2002. (HS-748) aircraft investigations in the 1970’s; and, [4] R Ramachandran, A visionary scientist , Frontline 19(2), in the 1980’s, he strongly urged NAL to champion Jan 19 – Feb 01, 20025. the country’s civil aviation programme. He could [5] A P J Abdul Kalam, Vision and leadership – be very forceful and demanding, and yet articulate http://presidentofindia.nic.in/S/html/speeches/others/nov18 his viewpoint with great charm and wit (he once _2002_4.htm remarked that, without a suitable aircraft Srinivas Bhogle National Aerospace Laboratories Bangalore 560 017, India. 5

Peof. Satish Dhawan Commemoration Lecture Dhawan and theTransformation of the Indian Institute of Science Dhawan took charge as Director of the Institute on In retrospect, Dhawan’s initial years seem to have the last day of 1962 and continued in the position till been taken up in consolidation and reorganization 31 July 1981. His tenure of more than seventeen of the units already on the campus; for example, in and a half years was the longest in the Institute’s 1963, the Power Engineering Department was split history for any director. Over this period Dhawan into the present Mechanical, Electrical and High was able to exert a long-lasting influence on the Voltage Engineering Departments. However Institute’s intellectual character, its programmes in towards the end of the 1960s, Dhawan began taking both research and education, and its administrative a series of new initiatives that transformed the structure. The period was also marked by an Institute in less than a decade. In 1968-69 a major extraordinary expansion in the diversity of the campaign to recruit new faculty, especially from research programmes at the Institute, as a large abroad, was set in motion. In 1969 the School of number of new faculty joined at various times and a Automation was set up with I G Sarma (who came variety of new centres were set up. Indeed, the from IIT Kanpur) as its first head; the School was Institute as we see it today is by and large the inspired by Russian ideas and was an unusual outcome of a series of changes that took place academic unit in the country at the time. In 1970 a through Dhawan’s tenure, at any given time computer centre was set up (with an IBM 360). The seeming to be incremental, but adding up over same year the teaching programme was nearly two decades to a remarkable transformation. reorganized (after overcoming much initial resistance) into a unit or credit system, giving much When Dhawan took over the Institue it was greater flexibility to the student. around that time a relatively small: around 1960 there were only 11 review committee headed by the well-known departments and 5 sections, the recurring budget chemist, T R Sheshadri, made a series of was Rs. 54 lakhs and the non-recurring budget just a recommendations about the administrative little more than Rs. 6 lakhs. The Senate of the structure of the Institute as well as its scientific Institute could sit around the oval table in the old programmes, endorsing some of the changes that Council Chamber on the ground floor of the Tower. Dhawan had already put in place. These included a (I attended one of its meetings as an invitee in the new system of promotion so that, instead of a single early 1960s.) By the time Dhawan left there were professor in each department who was also some 40 Departments and Units in the Institute, the automatically its head (or czar, as Dhawan recurring budget was approaching Rs. 10 crores and sometimes referred to them), there were now the non-recurring budget had gone up by two orders several professors; and departments were being of magnitude; at the farewell meeting in July 1981, grouped together into divisions to encourage the Senate filled a fair part of the Faculty Hall. (By interdisciplinary work and, more generally, to the way, the one departing plea he made to the break down the rather impenetrable walls that every assembled senators on that occasion was that they department at the Institute had erected around itself. should continue the tradition of deciding by consensus, and not be too impatient with minority In 1971, for the first time in the twenty years after he views; he hoped it would never necessary to count had joined the Institute, Dhawan took a sabbatical heads in the Senate.) break to spend a year at his alma mater, Caltech. But 6

Peof. Satish Dhawan Commemoration Lecture following the tragic death of Vikram Sarabhai he policies that were adopted at the Institute, the heads was asked by the Prime Minster, Mrs. Gandhi, to of departments now became chairmen holding their run the national space programme, and returned position for a few years and rotating it among other from Caltech in the middle of 1972 to assume the colleagues in the department. position of Chairman of the Indian Space Research Organization as well. He made it known, however, As both Institute and ISRO grew, there was great that IISc was not only his base but also his first pressure on Dhawan’s time; the appointment of S charge; so ISRO Headquarters were set up at Ramaseshan as Joint Director was of some help. At Bangalore, and Dhawan continued to take his salary his last meeting with the Council, Dhawan was for from IISc. once emotional; his voice faltered, and he was at a loss for words. (the awkward spell was broken In spite of holding these two jobs, Dhawan when he was called away to take a telephone call continued with his strong initiatives: the early 70s announcing the successful launch of the India’s first saw another major influx of talent to the Institute experimental geostationary satellite APPLE.) and the flowering of many scientific programmes. Thirty years at the Institute, more than half of that Dhawan invited G N Ramachandran to the Institute period as its Director, meant that his life and that of to set up the Molecular Biophysics Unit in 1971, the Institute were inextricably linked; the ‘idea’ of George Sudarshan to set up the Centre for the Institute, of what it ought to be, had consumed Theoretical Studies in 1972 and C N R Rao to set up him throughout that period. the solid State Structural Chemistry Unit in 1976 (followed by the Materials Research Laboratory in The Institute has continued to grow and flourish 1978). As a young faculty member at the Institute I under successive directors after Dhawan, and there could sense that in a matter of some six or seven have been many new programmes as well. But I years the intellectual character of the campus had think that in the eight years between 1968 and 1976 been transformed, and new disciplines, new ideas the character of the campus was changed, and new programmes had grown rapidly. There was irreversibly, as it now appears. In the 1959s the in fact a new buzz in the air on campus. It was Institute was by and large a laid-back campus, with characteristic of Dhawan that the new programmes the vigorous research group being the exception were spread across both science and engineering, rather than the rule. By the late 1970s research had and also included such areas as the application of taken firm root and was pursued with science and technology to rural areas (headed by unprecedented vigour across the campus, the A K N Reddy), a Centre for Electronics Design and number of reserach students as well as academic Technology (set up in collaboration with ETH staff having roughly tripled during Dhawan’s time. Switzerland) and the Centre for Scientific and The Institute as we see it today took birth in those Industrial Consultancy, a joint programme with years. TIFR on the applications of mathematics, and a research programme on atmospheric sciences. As R. Narasimha the number of professors in the Institute went up National Institute for Advanced Studies, dramatically, both because of those who joined IISC Campus, Bangalore - 560 012, India. from outside and because of the flexible promotion 7

Peof. Satish Dhawan Commemoration Lecture Doing Little Science with Dhawan Roddam Narasimha Roddam Narasimha is When I joined the Department of Aeronautical Engineering, Director of the National Indian Institute of Science, Bangalore, in 1953 for doing a Diploma (as it was then called), the ‘star’ in the Department was Institute ofAdvanced undoubtedly Prof Dhawan. His labs, his classes, his attitudes all Studies and Chairman of made an immediate and deep impression on the twelve new students who joined that year and enthusiastically yielded to the the Engineering spell of his personality. Here was a tall, young, handsome Mechanics Unit at the bachelor who drove up in a sporty little red MG, raced up the Jawaharlal Nehru Centre staircase that arches over the 7 ft X 5 ft tunnel, and came into the for Advanced Scientific classroom uttering a cheerful and smiling “Good Morning’’ – all Research, Bangalore. this at a time when the general atmosphere in the Department His research interests was rather stern and formal (although some of the other faculty were also pleasant enough, led by the German Head of the are fluid dynamics, Department, Prof O G Tietjens). problems in aerospace technology and in the Dhawan’s lectures were advanced, simple and elegant all at the same time, and quickly gave students a sense of confidence. atmosphere. Students liked his classes very much indeed, and for a variety of reasons; the first of these was, as I have already remarked, Prof Dhawan’s general cheerfulness in his approach to the subject as well as to the students. He took his teaching very seriously, and supplied his classes with plenty of notes, data sheets, diagrams and so on. He worked hard on all these – one would often see him in his office late at night – and he expected the students to work just as hard – which many of them cheerfully did. Another reason for the great popularity of his classes – last but not least, as they say! – was that if he was convinced you had understood what was going on, he was generous with his grades! Keywords It was in the High Speed Aerodynamics Laboratory that he had Satish Dhawan, skin friction, set up at the suggestion of Tietjens, however, that his personality supersonic wind tunnel. was most forcefully expressed. First of all, everything there looked different, and worked well. The laboratory somehow 8

Peof. Satish Dhawan Commemoration Lecture A fluid flowing past any surface, such as for example an aircraft wing, exerts a shear stress on the surface due to the action of viscosity; this stress, which varies from point to point, is in part responsible for the ‘drag’ of the surface, i.e. the resistance offered to its motion by the fluid. In the first half of the 20th century, the introduction of the idea of the boundary layer by Prandtl led to new and rational estimates of the skin friction, which was shown to depend on the Reynolds number (which is a non-dimensional number given by (flow velocity x characteristic length scale of the body)/the kinematic viscosity of the fluid). Although various experiments had confirmed the usefulness of the boundary layer idea, no direct measurement of the skin friction on a surface had been made, till Dhawan devised a floating element balance for making such a measurement. In this balance a small strip of the surface is isolated from the rest of it and is allowed to ‘float’, i.e. it is free to move against the stiffness of appropriate elastic flexures (springs). The deflection of the element is a measure of the skin friction it experiences. In the balance the measurement is made by a nulling technique by which the element is brought back to its original position by applying a force which then provides a measure of the skin friction. Dhawan measured the deflection through a linear variable differential transformer; the size of the element was 2 mm in the direction of the flow x 20 mm across, the movement of the element being of the order of a few thousands of an inch. The figures here show (a) design of the instrument and (b) the results of the measurement compared with the theories available at the time. Numerous such floating element balances were made after Dhawan’s work [3]. Figure 1a: Sketch of flat-plate installation in GALCIT 2½ by 2½ foot correlation tunnel. Figure 1b: Local skin friction in incompressible flow. 9

Peof. Satish Dhawan Commemoration Lecture Box 2. Shock/Boundary-layer Interaction In supersonic flow, the fluid can encounter sharp discontinuities in flow variables such as normal velocity, pressure, temperature, etc. at what is known as a shock wave. If a shock wave hits a surface, then ideal fluid theory lays down how the pa- rameters of the reflected shock are related to those of the incident shock. (Shocks are nonlinear waves, so the laws of reflection are not as simple as in classical optics.) How- ever it is well known that no matter how small the viscosity of the fluid (or more precisely how high the Reynolds number) the effects of vis- cosity will be felt in a thin boundary layer near the surface, and so shock reflection is not quite the process that this ideal fluid theory describes. The experiments of Liepmann, Roshko and Dhawan [4] showed that surface pressure does not exhibit a discontinuity at the shock impinge- ment point; there is a smearing out which is wider when the boundary Figure 2a. Reflection of shock wave from flat surface. d =30; M1 = 1.4; R = 0.9x104. layer is laminar than if it is turbulent (Figure 2a). In fact the flow can even go from laminar to turbulent in the neighbourhood of the shock impinge- ment point and so the reflection pro- cess can be quite complicated (Figure2b). Figure 2b. Model of shock-wave reflection from flat surface with laminar boundary layer. Incident wave dt=4.50; M1=1.44;R=0.9·106. 10

Peof. Satish Dhawan Commemoration Lecture managed to convey an impression of both science and engineering; The idea was to it had 100 hp compressors running supersonic wind tunnels, as get on with the well as lenses and galvanometers measuring what was going on in experiments those tunnels. Much of the equipment and instrumentation were whichever way made locally, for they could not be easily borrowed or bought: they might best be clearly the idea was to get on with the experiments whichever conducted. way they might best be conducted. I vividly recall how a small 1 in X 3 in supersonic wind tunnel was calibrated, with the help of all hands that could be mustered at any given time, to open valves, ring bells, take readings, click cameras, etc. – to a young student like me it was all very dramatic and modern. (Not that the number of people so mustered was very large: the Department was still small at that time.) There was also an earlier 1 cm X 1 cm supersonic wind tunnel, which ran on compressed air from two war-time surplus oxygen tanks from a Dakota – complete with a schlieren system which quickly demonstrated shock and expansion waves to students, and made them real at a time when, to most people, they were no more than fancy ideas in fancy foreign books. While I was working in the High Speed Lab, a low-turbulence boundary layer tunnel was getting ready, and as I joined as a research student in 1955 I moved to the new Boundary Layer Lab which housed this tunnel. Both laboratories had a variety of ingenious little devices, rigged up by Dhawan with great and obvious pleasure, to make things clearer for the student or easier for the experimenter. Among these “gizmos”, as he loved to call them, I remember a pretty little thing for electroplating 5 micron tungsten wires with copper, so that they could later be soldered for making hot wire probes – I started my life in the laboratory, like so many students of fluid dynamics everywhere in the world at the time, struggling to make these probes for turbulence measurements. I still recall Prof Dhawan teaching me how to make these probes, telling me about the strict ‘ritual’ one had to follow – “like doing pooja”, he would say. The fine wires we needed for these probes were not easily available, and Dhawan got them from friends in 11

Peof. Satish Dhawan Commemoration Lecture Box 3. Transition Fluid flow can exhibit either of two states, laminar (generally smooth and regular) or turbulent (generally irregular, chaotic, apparently random). In flow past any body or surface the state of fluid motion is usually laminar near the nose or leading edge, and undergoes ‘transition’ to turbulence further downstream. For a long time there were two contending pictures of how transition actually takes place: one seeing it as abrupt, the other as gradual – what experimental evidence there was could be used to support either view. It turns out that this transition does not occur across a sharp front but rather over a region, which can some times be quite extensive; the flow within this region is turbulent only part-time. The two pictures were reconciled when it was discovered that transition is characterized by islands of turbulence, called spots, which have sharp boundaries; the flow is fully turbulent only when the spots grow so big that they entirely cover the surface. The fraction of time that flow is so turbulent at any point is called the intermittency. The diagram here shows that, irrespective of the agent causing transition, measurements made at IISc and the National Bureau of Standards all follow a universal curve (Figure 3) [5]. Figure 3. Universal distribution of g vs x with transition due to different agents. the United States: various bits of platinum and tungsten wire arrived by mail, stuck on the back of letters written to him (we used to hoard them like misers). He would often rig up small experiments very fast, with what- ever was available. For example, I remember a tiny vertical wind tunnel made out of a drawing sheet rolled into a tube, with a little fan driving air through it from the bottom. Placed across the tube at the top of the tunnel was a ‘test cylinder’, which was just a fat wire, and students were shown the famous Karman vortices in the wake of that cylinder by the use of hot wire probes. 12

Peof. Satish Dhawan Commemoration Lecture Dhawan thought at the time that we needed to do something on transition from laminar to turbulent flow, because the wind speed and model size for the Department’s 5 ft X 7 ft tunnel left flow on the wing of a typical aircraft model in an awkward transitional state. It was characteristic of him to identify the nature of the problem with the tunnel, and so start a basic research programme to figure out if anything intelligent could be done about it. That is how I started studying transition for my Associate’s thesis. When I needed a hot wire amplifier for my research it had to be built from scratch (this was long before commercial sets became available in the market, and in any case we had very little money, especially in foreign exchange), so Dhawan hired a graduate from the Electrical Communication Engineering Department (P B Krishnaswamy) to help me on the project. We struggled for a year to put together a high-gain vacuum tube amplifier, operating on a 90 V dry-cell battery pack (of the kind that was still being used in the 1950s to run radio sets in villages). The amplifier seemed to suffer from every known instability (and some unknown ones as well – or so it seemed) before we had it working satisfactorily. Then we had to take photographic traces from an oscilloscope to measure intermittency – no cameras were available in the Department, and the one person who had it on campus would not dream of loaning it to us. So one day Dhawan asked, ‘Can’t we stick a film on a piece of wood and draw it across the oscilloscope?’ So I made a ‘linear’ oscilloscope camera, with a length of unrolled 36 mm film stuck on a sheet of plywood. This sheet was then pulled through a black box with a slit facing the oscilloscope. As the velocity of the film was hardly uniform, equal intervals of length on the film did not correspond to equal intervals in time. So I used beam intensity modulation to provide time markers and counted time intervals manually after the film was developed in a make-shift room in the lab But it worked – worked so well, in fact, that we could make good sense of the data, and even write a paper for the Journal of Fluid Mechanics, but more importantly I learnt how, with some ingenuity, one can overcome what seem like insuperable difficulties. 13

Peof. Satish Dhawan Commemoration Lecture Another pair of related incidents I must recall, because they show the way Dhawan worked with his students. As the boundary layer tunnel was calibrated and the hot wires began to work, Dhawan one day dropped on my desk a NACA report [1] on turbulent spots, which immediately seemed to provide a framework for understanding the transition zone. There was something strange in this work, however, because while it confirmed the value of the concept of a turbulent ‘spot’ that had been originally proposed by Emmons [2], the quantitative prediction of his theory was not compared with the experimental results that had been obtained. I was surprised by this apparent omission, but quickly found out why: when I made the comparison the disagreement was huge. As my thesis work began making some progress, I finally thought I had found a clue to the interpretation of measured intermittency distributions. Dhawan was convinced about the soundness of this work, and encouraged me to publish a note in the Journal of Aeronautical Sciences. Although it took me some time to figure out the reason for the huge disagreement, and where the theory had to be modified, in time the new hypothesis began to sound so reasonable – indeed obvious – that I was a little surprised that nobody else had thought of it. It so happened that at that time Dhawan had a stream of friends visiting him from abroad, and he would often leave them with me in the Boundary Layer Lab to discuss our transition work. One such was an Indian scientist working in the US, who found it virtu- ally impossible to believe that we might have done something new, and hinted how very unlikely it was that (with my crude, home-made dry-cell hot wire amplifiers) I might be right. I failed to convince him (although he seemed to have no specific scientific objections), and towards the end of our conversation he was well on the way to shaking my confidence. When I duly reported on the encounter to Dhawan, he was appropriately dismissive, so my confidence was restored. Fortunately some months later the famous Kurt Friedrichs from the Courant Institute visited Dhawan, who again dropped him off in the BL Lab. (Friedrichs was co-author, with Courant, of a book on 14

Peof. Satish Dhawan Commemoration Lecture supersonic flow and shock waves – a book that was very well A very strong point in known but was so mathematical that to most engineers it was the Department’s Greek and Latin.) After my earlier experience I started a little programme at that cautiously, but Friedrichs bought the argument right away. time was the way Indeed he was fascinated by what we were doing, and was that it combined, quickly asking rather deep questions to which I had no answers under Dhawan’s at all, but the very fact that he thought we might have them leadership, a wiped out the effect of the other encounter. concern for science with a A very strong point in the Department’s programme at that time responsiveness to was the way that it combined, under Dhawan’s leadership, a the country’s needs. concern for science with a responsiveness to the country’s needs. I am sure that all of Dhawan’s students were impressed by how, on the one hand, he was intrigued by the fundamental scientific problems in one’s own subject, and, on the other, driven by his desire to use one’s knowledge towards applications on a largerscale. In a very real sense I think Dhawan established, at IISc and – by example – elsewhere in this country, a tradition of scientific research on engineering problems. Suggested Reading [1] G B Schubauer and P S KlebanoffN,at. Adv. Comm. Aero,.Wash., Tech., Note no. 3489, 1955 . [2] H W Emmons,J. Aero Sc.i, Vol.18, p.490, 1951. [3] S Dhawan, NACA Report 1121, 1953. [4] H W Liepmann, A Roshko and S Dhawan, NACA Report 1100, 1952. [5] S Dhawan and R NarasimhaJ,. Fluid Mech,.Vol.3, pp.418-437, 1958. Address for Correspondence Roddam Narasimha Director National Institute of Advanced Studies Bangalore 560 012, India. 15

Peof. Satish Dhawan Commemoration Lecture About Prof. Satish Dhawan K Kasturirangan K Kasturirangan is Rare is the combination of academic degrees that Satish Dhawan had – currently a nominated BA in Mathematics and Physics, MA in English Literature, BE in member of the Rajya Mechanical Engineering, MS in Aeronautical Engineering and PhD in Sabha after having served Aeronautics and Mathematics – but rarer is a human being of his kind – a in the ISRO establish- loveable teacher, an intense researcher, an innovative technologist, an able institution builder and an excellent academic administrator, all at ment for over three the same time but distinctly visible. decades. His main interests are high energy Dhawan took over the reins of the Indian space programme at a very astronomy, optical crucial stage of its infancy when Vikram Sarabhai passed away in astronomy, satellite December 1971. He could efficiently consolidate the efforts of Sarabhai technology, and remote and gave a concrete shape to his dreams by nurturing the space progamme through the most critical phase and making it to mature to a sensing. stage of yielding several benefits to the country. He had a great foresight for managing a multi-disciplinary and technologically complex space programme in governmental set-up. His strategy of organizing the programme was unique. He carefully worded, perhaps, bringing to bear his deep knowledge of English, the resolution setting up the Space Commission and Department of Space, which read: “In order to promote a rapid development of activities connected with the Space Science, Space Technology and Space Applications, the Government of India consider it necessary to set up an organization, free from all non- essential restrictions or needlessly inelastic rules, which will have responsibility in the entire field of Science and Technology of Outer Space and their Applications”. Being a researcher, a technologist and having led a reputed academic institution like Indian Institute of Science for several years, he knew the importance of insulating the professionals from the drudgery of bureaucracy. Keywords Dhawan had a very intense feeling of technology and, more Satish Dhawan, ISRO Arya- significantly, an exceptional depth of understanding of its relation with bhata, satellites. the society. His concern was to make space technologies like remote sensing and communication relevant to the society. He knew that if this had to become a reality, he had to institutionalise their implementation. 16

Peof. Satish Dhawan Commemoration Lecture He created the INSAT Coordination Committee, a unique inter- ministerial forum with participation of end users like the Department of Telecommunication, Information and Broadcasting, Department of Science and Technology for evolving and implementing the INSAT system. By the time INSAT system was commissioned in 1983, the users had been prepared to use the system that brought a revolution in communication, broadcasting and meteorological services in India. He created the National Natural Resources Management System (NNRMS) and a Planning Committee of NNRMS under the Chairmanship of Member, Science, Planning Commission, to evolve and implement Indian Remote Sensing (IRS) satellite system and its application to various fields. He did not over look space science, which was always dear to his heart. He made sure that the space capability and space science go together by setting up an Advisory Committee on Space Sciences (ADCOS) with multi-institutional participation. If the Indian space programme has great relevance to the country today and its sustainability no more in doubt, it is because of the close interfaces that he established with the users. It was a Herculean task, which only he could achieve, considering that he had to deal with a large and complex country, bring an awareness among an even more complex governmental system and a bureaucracy managed by those who are not necessarily technically oriented and, ultimately, integrate the space system into the conventional systems. It is easy to say that space can provide communication and timely information on resources, but it was Dhawan who addressed the questions like who will use it and how they will use it and how it will reach the society at the grassroots. Dhawan was a person who could think well ahead. It was his strategic decision that kept the Headquarters of Indian space programme in Bangalore, not because he wanted to run the space programme even as he continued his academic administrator’s role as Director of the Indian Institute of Science but because he knew that Bangalore had several advantages. The city could accelerate satellite building activities, which had just been taken up, using the institutions like IISc, National Aeronautical Laboratories (now called National Aerospace Laboratories) and industries like Hindustan Aeronautics and Bharath Electronics. Besides its salubrious climate that facilitated the fabrication 17

Peof. Satish Dhawan Commemoration Lecture of satellite systems, the academic, industrial and research ambience of the city were decidedly advantageous. Personally, I came in contact with Dhawan when the project to develop the first Indian satellite, Aryabhata, was initiated. I was fortunate to work with him very closely and learn from him the nuances of space programme management, which has brought to bear in my leading the programme later for nearly a decade. When we started the Aryabhata project, with U R Rao as the Project Director, there was no time to put up buildings and other infrastructure and, in order to meet the international commitment of readying the satellite in time for launch on board the Soviet Union’s Inter Cosmos rocket, we selected a few industrial sheds in Peenya, on the outskirts of Bangalore to design, develop and test the satellite. It is interesting to recall the events that preceded the approval of the Aryabhata project itself. When the offer came from the erstwhile USSR for launching an Indian satellite, the then Prime Minister, Smt Indira Gandhi, wanted the decision on accepting the offer within 48 hours and also the details of the terms and budget outlay. We worked through the night to come out with a budget figure Rs. 50–60 lakh that looked ridiculously low. We decided to multiply all our estimates by 6 and the total outlay came to a respectable Rs. 3 Crore. M G K Menon, who was leading the Space Programme temporarily at that time, submitted the same to the Prime Minister. After Dhawan took over as Chairman, ISRO, he asked us about the logic behind the budget figures and he even asked how we decided to multiply the estimates by 6 and not any other number! He would not let anything unanswered and would convince himself before decisions were taken. Being the first major space project of India with an international commitment, Dhawan decided to be the Chairman of the Aryabhata Project Management Board, the only project board for which he was the Chairman. He always believed that he should not be directly in charge of major activities himself but make sure that works and responsibilities are delegated. As secretary to Aryabhata Project Board, I can vividly recall the meticulous way in which he looked at the issues – technical, programmatic, financial, schedule or infrastructure – and the follow-up actions. He was deeply concerned about the success of Aryabhata because, as he told several of his close colleagues, it was the first opportunity for India to prove that it could build a space system and if it 18

Peof. Satish Dhawan Commemoration Lecture failed, the credibility would be lost. I used to admire the way he conducted the meetings meticulously every three months, coming to the Peenya sheds with other members like Brahm Prakash. He would not only check the technical details but also, as a true English Professor, look at the language – every comma, hyphen and semicolon. Once I had written a paragraph on our assessment of a technical issue and concluded that there was no problem on that issue. He had remarked in his own beautiful handwriting against this paragraph “there is no problem? – I am worried”. As a technical administrator, he could not believe that there could be no issues in a project that was being executed for the first time in the country. After the successful experimental project, Aryabhata, it was Dhawan’s initiative to proceed directly to an application oriented experiment, the Bhaskara-1 project. Bhaskara-1 had to be of low cost of about Rs 4-5 Crore, technologically feasible, realisable in 3-4 years and have some meaningful utility. He had more confidence in us than we had in ourselves. He made us realise this project, in time and within the budget. When the satellite’s television camera initially had a problem due to suspected high voltage corona, he made us simulate the problem on ground to understand it and decide on the remedy. The work involved placing a similar system in the thermo-vac chamber, conducting off-line experiments and modeling. We concluded that there was some trapped gas in the satellite which could possibly escape if we wait for 5 to 6 months. Six months later, the camera was switched on and indeed, it worked and we were thrilled. Dhawan had bet his one-month salary with one of his junior colleagues who was very confident of the camera coming through and Dhawan lost the bet. He promptly handed over his one month’s salary to his jubilant colleague. But the amount was unfortunately just one Rupee! Since Dhawan was also the Director of IISc and drawing salary there, he was taking only a token salary of one Rupee from ISRO. Perhaps he was so confident that the camera would work and did not want to stake more than a rupee! Dhawan was “seriously humorous” with his colleagues and this way he used to establish a long lasting personal rapport with them. It was Dhawan, the original thinker, who decided the final configuration of Polar Satellite Launch Vehicle, PSLV, which is the work horse launch vehicle of ISRO today, with six successful flights so far. It was his 19

Peof. Satish Dhawan Commemoration Lecture judicious decision, based on a combination of factors including technical capabilities, infrastructure, schedule, financial and project management that resulted in the unique solid-liquid-solid-liquid configuration for PSLV. He configured it keeping in view the expertise and aspirations of highly committed and talented people. He was indeed an outstanding techno-economic administrator. When PSLV had its first successful flight in October 1994, he had a sense of satisfaction. But it was only its second success that assured him that PSLV had indeed come of age. He acknowledged this when he gave me a bear hug, which I cannot forget. Dhawan’s foresight came to my notice again when, as Project Director of Indian Remote Sensing satellite, IRS-1A, I was drafting the contract for its launch with the Russians. He made sure that all contingencies that could arise in the following six years, before the satellite’s launch, were well thought of in drafting the contract. He jokingly remarked after going through the document “I will hold you responsible if you make any changes on it later”. It was the first commercial agreement with Russia for launching a satellite and the first to be signed by Dhawan himself. I had more intense interactions with Dhawan after I took over as chairman of ISRO in October 1994, which exposed me to his concern for the society and his view that space be never used as a technical bonanza but only as a tool to develop the society at the grassroots. He was deeply concerned about the lower strata of the society, always trying to see how they could be fruitfully employed even if they are unskilled or illiterate without displac- ing them or altering their pristine cultural heritage. His view of the impact of technology was very different than many professional technologists, economists, or sociologists. He expressed his views when ISRO took up the task of identifying and delineating 13 types of wastelands in the country using data from Indian remote sensing satellites. These maps are prepared and updated to help reclaim the lands for agricultural and other uses. When I took copies of these maps to Dhawan, he viewed the whole exercise from an entirely different aspect. He said “this is all very good and these maps are very useful to develop this country. But do you know that wastelands in our country are not a waste? There are tribals and others who depend on the produce of these so-called wastelands. If you start water recharging and improve the water availability in these lands to improve the vegetative cover, the whole place may look very promising to prospective developers. Then these 20

Peof. Satish Dhawan Commemoration Lecture tribals will be disturbed and there will be no system to protect them”. He even cited the example of aqua-culture, initiated to bring prosperity, which resulted in several traditional fishermen and others along the coast being displaced. Even though they were given some 10,000 rupees each, they did not know how to manage that money and, within months, they frittered it away and were left in the lurch. In a lecture delivered at the Indian Institute of Technology, Chennai in February 1976, Dhawan explained how a technology related to rocket propellant, developed by the Vikram Sarabhai Space Centre, Thiruvananthapuram, could trigger developments that could benefit millions of unskilled, illiterate and predominantly tribal population. The technology related to developing polyols using naturally available oil seeds that could lead to production of other petroleum products. The project involved collection of seeds, both cultivated and uncultivated, from Castor, Mahua, Pisa, Neem, etc, de-hulling, transportation to oil extraction centres and transportation of oil. The capital investment estimated was Rs 190 crore and operating cost Rs 461 crore while the value of the product was estimated at Rs 487 crore per year. Further, it would have resulted in about 4 million tonne per year of non-polluting, non-toxic and biodegradable manure that would have significantly enhanced agriculture and food production. Dhawan was peeved when the project was shelved due to economic consideration. He felt that the feasibility study was purely an economic analysis and did not assess the sociological benefit that would have accrued to a million grassroots level population. While most believe that development and progress means economic prosperity, Dhawan viewed it as that related to the very grassroots level people of the country and their lives. For him, the impact of information created by even the most sophisticated technology was of no use if it did not address the grassroots realities of the country. His views were revealing and were of great value to keep one’s foot on the ground even while being enthusiastic about a new and promising technology. Dhawan was a keen observer of Nature. He had great admiration and fascination about the phenomena in Nature and always curious to learn from it like a true scientist. His observation of birds’flight resulting in his research into the various aspects of their flight, including painstakingly collected photographs of birds in flight, is indeed an outstanding contribution to the aeronautics field. This is very characteristic of an 21

Peof. Satish Dhawan Commemoration Lecture intense researcher as evident from the lives of scientists like Archimedes who discovered the laws of buoyancy while taking bath or the greatest Briton, Isaac Newton, discovering the laws of gravitation while observing a falling apple. Dhawan was also very innovative in designing his own research tools; he made the first precise direct measurement of skin friction on a flat plate by designing a special balance which was later widely adopted and used in many laboratories across the world. Further, he was responsible for setting up several aeronautical research facilities including wind tunnels for the first time in the country. A great analyst and a man who could look at a problem from different angles, Dhawan was entrusted with the responsibility of reviewing the flight worthiness of the Indian Airlines’ Avro aircraft after it met with a few mishaps in the sixties. He completed his assignment with high credibility and confidently proved their airworthiness and indeed Avro aircrafts were hovering over the Indian skies for a long time after their proven flightworthiness. ISRO has named its Launch Dhawan’s leadership came to the fore when ISRO had to face several Centre at Sriharikota as Satish setbacks like the failure of the first flight of SLV-3. Outwardly he told Dhawan Space Centre – SHAR “we have stumbled but we have not fallen flat” but he was deeply upset. He never showed his feeling that he was disappointed with the team or any individual. Further, he never spared any effort to identify the problem and ensured that it was corrected. It was his encouragement and his deep interest to learn from failures that made ISRO recover fast and fly SLV-3 successfully in the very next flight. And today, ISRO has the resilience to face any challenge even in the face of a few setbacks here and there, thanks to the early culture and outlook. AShubhashita Sloka says Address for Correspondence (When the sun is rising it looks reddish when setting also it is reddish. K Kasturirangan Great men look alike in times of happiness or distress. ) Member of Parliament and Dhawan was indeed a great man to remember and to emulate. Former Chairman, ISRO 22

Peof. Satish Dhawan Commemoration Lecture Bird Flight and Satish Dhawan: Some Thoughts K R Y Simha Great scientists like Newton, Darwin, Einstein, and Raman dreamed K R Y Simha is a freely to unveil the mysterious beauty of natural phenomena. Early Professor at the engineers built castles, dams, bridges, boats, looms, pyramids and mills Mechancial Engineering by trial and error. Science kept far ahead of engineering until the Department, Indian twentieth century. The first twenty years of the twentieth century Institute of Science, witnessed the beautiful minds of Einstein, Planck and engineers like Bangalore. His interests Prandtl, Ford and the Wright brothers. However, World Wars 1 and 2 are solid mechanics, shattered the utopian spirit of unity, cooperation and trust among fracture mechanics, scientists. Applications of science and mathematics to engineering and shock and impact medicine in the aftermath of the wars has created huge business opportunities for universities, laboratories and corporations. Modern mechanics. scientists seem to be getting increasingly obsessed with seasonal and sensational problems rather than solving philosophically deeper issues. Keywords One such issue is bird flight, a subject in which Satish Dhawan evinced a Birdflight, Satish Dhawan keen interest. It is indeed a glaring irony that despite powerful computer and information technologies aiding science, nothing spectacular seems to have emerged after the double helix. This does not mean that all problems have been solved; it only means that non-lucrative esoteric ideas are unviable. Science of degradation of life and environment could solve the mystery of extinction of several species of birds, insects and animals as also human immunity to disease. Similarly, cataclysmic signals from cosmic explosions billions of years ago reaching us now are screaming for explanation. Science too seems to have degenerated into just another profession. It is at this desperately critical juncture that reviving classics by Darwin, D’arcy Thomson and Feynman could perhaps steer young and pristine talent towards the pure and mysterious beauty of nature. 23

Peof. Satish Dhawan Commemoration Lecture We should The 1988 CSIR Raman Memorial Lecture on bird flight was delivered by encourage a great orator: Satish Dhawan. For those who missed this lecture, he students to take prepared a 77 page article for Sadhana in 1991. Fortunately for some of interest in studying us, oratory history repeated during the Golden Jubilee Lecture Series of the grandeur of the Department of Mechanical Engineering, Indian Institute of Science, natural flora and Bangalore in 1995. Dhawan spoke for about an hour on bird flight ending fauna. Nature his talk with a high speed movie. Having both heard and read Dhawan’s protects us if we articulate eloquence, it is amazing how little we appreciate the supple protect nature. structure and subtle flying techniques of birds. Compared to birds, flying machines are monotonous, dull, loud, costly, unstable, and dangerous to our health and environment. It is precisely this terrifying reality that has nearly grounded Concorde – one of the most advanced supersonic jet aircraft in the history of aviation. It is also for this reason that we should encourage students to take interest in studying the grandeur of natural flora and fauna. Nature protects us if we protect nature. Like crystals, birds may be grouped and the approximate 9000 species of birds are grouped into 27 orders. Dhawan cites an ornithologist James Fisher who established that there are close to a 100 billion birds with South America nurturing over 3000 species, Indian subcontinent 1200 species while North America, Canada and Russia supporting only 700. There is a definite link between birds and environment. Birds avoid congested places devoid of clean air and water. Dhawan’s fascination and admiration for bird flight is infectious when he begins the Abstract and Introduction. “Avian flight has fascinated man from ancient times but it is only in recent years that the efforts of scientists from diverse fields have been able, to some extent, to understand and explain the dynamics of animal flight... . Observation show an incredible diversity of flight techniques and maneuvers... Since time immemorial man has been fascinated and intrigued by the beauty, grace and intricacies of bird flight. There is perfect harmony of form and function. It is equally exhilarating to attempt to understand how the physiology and performance of birds are related through scientific principles.” 24

Peof. Satish Dhawan Commemoration Lecture With his monograph on bird flight [1], Dhawan joins a special set of people who believe nature as the greatest of all teachers. Nature in all her wild fury of fire, wind, rain and thunder together with other beautiful forms of living nature like flowers and birds has inspired poetry, art, literature, science and technology. In Monsoon, Wilbur Smith [2] narrates the kinship of Tom and his younger brother Dorian with an albatross keeping company with their ship. The narrative is scientific in describing the magnificent flying skills of this gentle giant (see Box 1). Henk Tennekes, an aerospace engineering professor at Pennsylvania State University, USA, has a different story to tell in his popular book The Simple Science of Flight: From Insects to Jumbo Jets [3]. Introducing the book, the author laments that modern education has ignored connecting nature and technology, and exhorts teachers and students to hone their experimental skills (Box 2). Comparing birds with aircraft is a popular pastime for pilots and the public alike, but it is important to emphasize that bird flight is seldom Box 1. One day out of the great wilderness of the water there came an albatross. Circling the ship on wide pinions, dipping and rising on currents of air, gliding and planing, sometimes so close to the crests of waves that it seemed to become a part of the spume, it kept station with the ship for days on end (Figure A). Neither of the boys had seen a bird of that size before. At times it sailed close to where they crouched in their barrel shaped perch, seeming to use the updraught from the Seraphs mainsail to hold its position, never flapping its Wings, only gently fingering the air with the black feathers at the tips. Dorian particularly delighted in the creature whose wingspan was three or four times that of his arms. Mollymawk! He called it by the sailors pet-name meaning Stupid Gull, for its trusting, confiding nature when it settled to earth. Dorian had begged scraps of food from the ships cook and tossed them to the circling bird. Very soon the albatross had learned to trust and accept him, came winging to his whistle and cry. It sailed beside him almost close to touch, hanging almost motionless in the air, daintily snapping up the morsels he threw to it. On the third day, while Tom hung on to his belt to prevent him falling, Dorian reached out as far as he could with a piece of fat salt pork in his hand Mollymawk regarded him with a wise, ancient eye, banked on his spreading pinions, and took the offering from him with a delicate pinch of his formidable curved beak, which could easily have lopped off one of the boy’s fingers. Box 1. continued... 25

Peof. Satish Dhawan Commemoration Lecture Over the next few days Mollymawk grew tamer and more confiding towards Dorian. ‘Do you think he loves me, Tom? I shall want to keep him forever as my pet.’ But on the eighth morning when they climbed to the masthead the bird had disappeared. Though Dorian whistled for him all that day, he was gone, and at sunset the child wept bitterly... Figure A. Theory of dynamics soaring (Lighthill 1975). (a) Phases in the soaring flight of an albatross. (b) Dynamic soarind: (1) rise into wind, (2) turn at highest point, (3) glide down wind – build up of speed, (4) turn and repeat (1). (From S Dhawan, Bird Flight, IASc) steady. Most birds are either flying up or down or swinging left or right, enjoying all the degrees of freedom. The hummingbird can hover like a helicopter, and even fly backwards! Each wing flap and tail flick is executed artistically and effortlessly to aid birds meander through brush, woods or buildings. In this respect, fighter aircraft designers are studying birds closely to build lighter machines for speed and agility. 26

Peof. Satish Dhawan Commemoration Lecture Box 2. The book is an act of revenge on the part of an assistant professor of aerospace engineering who dared to use flight calculations of ducks, geese, sparrows, and butterflies to entertain his class on aircraft performance. Two particularly humorless students complained to the head of the department: “We are studying aeronautical engineering because we are interested in aviation. Nowhere in the curriculum does it say that we have to study biology as well. Would you please ask Professor Tennekes to stick to the official syllabus?”... “Henk, some of your students have complained”, said my department head. “In you class you seem to have talked about geese and swans. I cannot condone that. Our profession – mine, and I trust yours, too – is a branch of engineering.Animals that flap their wings are none of our business. Please restrict yourself to airplane theory.” I was flabbergasted. It took me almost a minute before I managed to respond. “But the same theory applies to the performance of birds. Isn’t that a nice bonus?” I have always been fascinated by the similarities between nature and technology. I learn by association, not by disassociation. Weren’t a swan and a 747 designed with the same tender loving care? Notwithstanding their differences, they follow the same aerodynamic principles, and it is nor that hard to explain how these principles work... Very recently, McNeill Alexander has written a book on principles of animal motion including bird flight [4]. Clearly, the list is growing changing the mindset of students, teachers and scientists. Students, teachers, scientists, general public and mass media are actively promoting field trips and lectures to learn more about our environment through birds [5]. Camping around SHAR and the Nelapattu Sanctuary, Professor Dhawan distilled the essence of bird flight for the expert and the neophyte alike. The sheer biometric diversity of birds and their complex modes of flight have challenged scientists, evolutionary biologists and mathematicians. Conventional aerodynamic scaling concepts fail to explain subtle features of bird flight, as debated by over fifty delegates in 1975 at Cambridge [6]. In particular, T J Pedley who edited the proceedings praised the pioneering work on hovering by Torkel Weis-Fogh and James Lighthill. Explaining this unique skill of tiny birds perhaps holds the key for linking birds and insects on the evolutionary totem pole. Kingfishers, sunbirds and hummingbirds are masters at hovering. The mesmerizing sight of these birds suspended in air has inspired over a dozen aerodynamic models. Insects and birds defy gravity by inducing a steady downward air stream like a ceiling fan by 27

Peof. Satish Dhawan Commemoration Lecture Kingfishers, simultaneous flapping and twisting of wings. Hummingbirds are also sunbirds and capable of flying backwards! Dhawan highlights the biomechanics of hummingbirds are such magical avian feats including a cinematographic analysis of masters at hovering. egret’s take-off. This feat is illustrated with a simple plot of the The mesmerizing temporal evolution of the flight path (Figure 1). It is amazing that this sight of these birds bird is airborne by flapping its wings twice within a matter of few suspended in air hundred milliseconds. This data can be processed further to obtain has inspired over a power and energy needs. dozen aerodynamic Hovering and take-off make enormous demands on muscle power models. impossible to imagine in other animals. The sheer elegance of this extraordinary aerodynamic event is captured on the cover page. To those who knew him, Professor Dhawan believed in the very best of science and society. This conviction inspired successive generations of students, professors and scientists to excel in their work. The only award or reward was the sheer intellectual excitement of creating new results for self-reliance and eradicating ignorance. With these ideals Dhawan propelled higher education and space research in India to attain the status that it enjoys today. Even after formal retirement, Dhawan took active interest in various activities of Indian Institute of Science. The following anecdote provides a glimpse of this unique personality. In 1962 just before he became Director of IISc, Dhawan enrolled a young student for a laboratory course on aerodynamics. This student completed his doctorate in aeronautics and became his colleague. Many decades later, long after Professor Dhawan had retired, this younger colleague invited his teacher to attend a flight demonstration of LCA scale models at Jakkur. The event was scheduled for 1000 hrs on the morning of September 3, 1998. Due to heavy traffic, the host turned up ten minutes late! Professor Dhawan chided his host for being late: “You should allow for traffic delay in your planning!” Once the trials commenced and enthralled everyone, Dhawan remarked: “Now, I believe the LCA will fly.” Delighted, the same day he wrote a letter of appreciation thanking his host for inviting him. The host – S P Govindaraju, who narrated this incident provided a 28

Peof. Satish Dhawan Commemoration Lecture scanned reproduction of this treasured letter showing a flying bird Figure 1. A study of the (Box 3), and also wrote a specialist review of Dhawan’s book on bird egret take-off. The hori- flight which appears in this issue. This human quality of spontaneous zontal distance from the and sincere praise Professor Dhawan lavished on his students and starting point (in cm) is plot- colleagues endeared him to the people. ted against the height above ground level. The It is remarkable that Raman and Dhawan studied nature to enrich their number within the circle respective professions to help launch Bangalore to a premier position indicates milliseconds af- in world science and technology. Bangalore is rapidly losing a lot of ter start. The number be- her charming gardens, lakes and birds except for some dashing green low the circle indicates the barbets and some sparkling sunbirds. But the charming spirit of level. Note that between Dhawan will continue inspiring students, teachers, naturalists and levels 4 and 6 the bird drops environmentalists besides aerospace scientists and engineers. about 10cm as its flight has Reviving nature classics in science journals could perhaps revive the not fully stabilised. At level philosophical spirit of science among young students and scientists. 12 the bird’s speed is ap- proximately 10m/s and its climbing rate is about 0.33 m/s. (From S Dhawan, Bird Flight, IASc) 29

Peof. Satish Dhawan Commemoration Lecture Box 3. Bird Flight, Academy Proceed- ings in Engineering Sciences, R e p r i n t e d f r o m S a d h a n a, Vol.16, Part 4, December 1991. Address for Correspondence Suggested Reading K R Y Simha [1] Satish Dhawan, Bird Flight, Sadhana, 16(64), pp. 275-352, Dec Mechanical Engineering 1991 Department [2] Wilbur Smith, Monsoon, Pan Books, 1999 [3] Henk Tennekes, The Simple Science of Flight: From Insects to Indian Institute of Science Jumbo Jets, The MIT Press, 1997. Bangalore 560 012, India. [4] R McNeill Alexander, Principles of Animal Motion, Princeton University Press, 2003. [5] Madhav Gadgil, Project Landscape-9, Crows, Resonance, Vol. 6, No. 2, February 2001. [6] Scale Effects in Animal Motion, Ed. T J Pedley, Academic Press, 1977. 30

Peof. Satish Dhawan Commemoration Lecture Satish Dhawan – A Creative Teacher A P J Abdul Kalam A P J Abdul Kalam, President of India, worked with the Indian Space Research Organization 1964-1982, and with the Defence Research and Development Organization 1958-1963 and again 1982-2001. In 1997 the Government of India conferred on him its highest civilian award, the Bharat Ratna. On many occasions during his long and illustrious career he worked closely with Professor Satish Dhawan. He recounts these events in the following pages, written from a personal point of view. M K Chandrashekaran When I think of the teaching qualities of Prof. Satish Dhawan, my thoughts go back to my days in the ADE during 1959-1961. At that time we were designing the Hovercraft “Nandi”. One of the typical design problems of Hovercraft was the design of a contra rotating propeller. I knew how to design a propeller, but I had no clue about the design of a contra rotating one taking into account the duct effect. I asked Dr. Mediratta, the then Director of ADE, whether I could seek the help of Prof. Dhawan for this design, since my friends had told me about his great teaching abilities. Dr. Mediratta agreed and I went to Prof. Dhawan. At that time Prof. Dhawan used to work in a small room in the IISc campus. When I asked him for help in the design, he said he would teach me how to design a contra rotating propeller, but I would have to come to him for ten Saturdays from 2 to 3 in the afternoons for learning the design. It was a great teacher's offer. I was jubilant and started attending the classes. He taught me how to design it. After the first lecture, before beginning the second one, he asked me critical questions pertaining to the first lecture. He tested the degree of my assimilation and application Keywords Satish Dhawan, SLV-3, ISRO, potential. With this background, I attended all the ten lectures and I developed the confidence that I could design the contra rotating INSAT, IRS. propeller. 31

Peof. Satish Dhawan Commemoration Lecture * 1A kind of wood. After completing the course he asked me to design the propeller. He reviewed the design and asked me to go ahead with fabrication, I needed Andaman Padauk1 for the fabrication but it was not readily available. He helped me to get the Padauk from HAL. After getting it I proceeded with fabrication involving multilayer sandwich construction and assembly. Once it was assembled, he asked me to take it to the test bed and start testing. I started facing some teething problems, particularly in the clearance between the duct and the propeller tip at the maximum velocity point. I solved the problem with the help of Prof. Dhawan and reached a stage of smooth test phase. The propeller went through 50 hours of continuous testing without any problem. Once we reached this stage of trouble free operation, Prof. Dhawan was very happy. Abbreviations used The unique feature of his teaching was that he created a spirit of research ADE – Aeronautical Development and inquiry in me, taught me how to design without giving me the design. Establishment He enriched my design capability by following through the IISc – Indian Institute of Science, implementation and test phase, just by asking more and more questions Bangalore and making me find the answers for them. This enhanced my self HAL – Hindustan Aeronautics confidence in taking up future design problems. Also during the teaching Limited, Bangalore phase, he permitted me to use the IISc library and gave me five books. SLV – Satellite Launch Vehicle For the first time I saw such a big library. My love for libraries and books ISRO – Indian Space Research was triggered by this single learning experience from Prof. Satish Organization Dhawan. INSAT – Indian National Satellite IRS-2 – Indian Remote Sensing ABeautiful Day Satellite. DRDO – Defence Research and 18th July 1980 is a memorable day for the entire space community of Development Organization, India. This was the day the space scientists put a 40 Kg Rohini satellite in Hyderabad a low earth orbit through SLV-3 which took off at 0805 hrs; within DRDL – Defence Research and minutes the satellite was in orbit. This was a great accomplishment for Development Laboratory our scientists, especially after an unsuccessful earlier mission on 10th August 1979. There was jubilation all around. People were thrilled. They were shouting, hugging and lifting each other and were emotionally charged. This was the time Prof. Dhawan took me aside and said that we should go to a silent place. Both of us went to the launch pad and sat on the launcher. We watched the waves of the Bay of Bengal in silence. 32

Peof. Satish Dhawan Commemoration Lecture After a few minutes Prof. Dhawan said to me: “Kalam, you know you have been working hard for the last eight years. You encountered a number of problems and failures. You faced them all with utmost courage, patience and perseverance. For all the efforts that you put in, today we have got the results. I want to thank you for your excellent work. I will remember it and cherish it”. I had never come across such a beautiful day till then. In the din of loud external jubilation of the entire space community, Prof. Dhawan and I were enjoying the intrinsic beauty of the mega event. Vision for the Space Programme After completion of the SLV-3 programme in July 1980 Prof. Dhawan asked me to take up the Space Launch Vehicle Directorate at ISRO Headquarters. The major task given to me and my team was to bring up the space programme for remote sensing and communication satellites linking the corresponding launch vehicle systems including the launch complex. We worked for nearly ten months linked with Vikram Sarabhai Space Centre, ISRO Satellite Centre, Sriharikota and Space Applications Centre. We designed and developed a six degree of freedom simulation model integrating the progress of technology in different disciplines. During this phase Prof. Dhawan used to drop into my office frequently to suggest ideas for the evolution of the space programme. We would explain to him the possible scenarios on the black board. We practically clinched the profile of the spectrum of communication and remote sensing satellites required for the nation during the next two decades. One evening he sat down and drew the entire road map for the space programme and depicted them in his own hand in two simple graphs which then became the driving force for the entire Space Department for the next two decades. The two graphs are given in p.60. As visualized by Dhawan, as a communication satellite a multimission INSAT was built, launched and operationalised. The INSAT series later reached a 2000 Kg satellite with a large number of transponders. In the remote sensing area IRS-2 has established our satellite's unique performance and can compete with world class satellites. Just when we completed the work relating to the drawing up of the 33

Peof. Satish Dhawan Commemoration Lecture ‘vision’for the space programme my posting to DRDO, Hyderabad came up. Prof. Dhawan was reluctant to relieve me for this task. However, after the Defence Minister made a special request he agreed to spare me to take over as Director, DRDL, Hyderabad on 1st June 1982. I had worked in ISRO for almost two decades, and Prof Dhawan gave me a unique send off. On 31st May, 1982, he organized an ISRO Council meeting which was attended by all the Directors of ISRO Laboratories and headquarters. He asked me and my team to present the Space Vision profile to the ISRO Directors. At the end of the presentation he broke the news about my posting to Hyderabad as Director, DRDL and converted the Council meeting into a send off meeting followed by a good dinner. Prof. Dhawan's elegant way of making me a part of the future space programme coupled with a warm send off enriched my life and made me ever grateful to the institution for which I had worked for so long. Prof. Satish Dhawan: a Lover of Nature Prof. Dhawan selected me as Project Director of SLV-3 – the first satellite launch vehicle to inject the Rohini satellite into a near earth orbit. During the ten years of my close association with him at ISRO, I had observed a unique quality in him. Apart from his excellence in science, technology and management aspects, Prof. Dhawan was a lover of Nature, particularly of birds. The roaring sea waves at Thumba (Site of the Vikram Sarabhai Space Centre) and at Sriharikota (Satellite Launch site of ISRO) and the dynamics of bird flight made Prof. Dhawan compare Nature's marvels with human life. When the sea becomes rough in cyclonic conditions, it generates a lot of turbulence and pain all around as we had witnessed in Sriharikota. Human beings should take a lesson from this and learn how to be calm in such a situation and be dynamic to encounter and solve problems. I still remember two events which brought Nature very close to him. The first event was the selection of the SLV-3 launch complex in Sriharikota, with launch pad, block house and rocket integration facilities. When the site and building plans were presented to Prof. Dhawan at Sriharikota near the site, he found that it needed removal of 34

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Peof. Satish Dhawan Commemoration Lecture ten thousand trees, and it was a great shock to him. He was so much concerned about the trees that he discussed with the team for two hours to find out the methodology by which the mission requirements could be met without uprooting all the trees. After prolonged discussions, a new site configuration emerged needing a removal of only a thousand trees. He agreed to this solution stating that they should make arrangements to plant ten thousand saplings in that area. And also for the first time an official order was issued to all the Directors of ISRO Establishments stating that “no tree should be removed without specific clearance from the Chairman of the ISRO, in any Establishment”. Today we find Nature smiling at us, full of trees and flowers, when we walk through any ISRO Establishment. The second event occurred during the Satellite Launch Vehicle programme. Prof. Dhawan used to visit all the establishments once in a month. He would review the projects continuously for four hours, visit the work centers and project sites and give suggestions for the timely completion of the projects. Generally he would not be available for two periods in a day, namely 4.30 to 8.00 in the morning, and 4.00 to 7.00 in the evening. During these periods he used to go into the forest with the photographer, Mr. K R Seetharam, with a small bag on his shoulder and a water bag. After visiting the forest area, he would walk all through it looking at various types of birds and their dynamics of flight. One day during his forest visit he observed a fleet of Siberian birds and then for the whole day he talked about the dynamics of that bird! His research established the framework for flying, wing profiles of the bird, structure and action of muscles, wing shapes and the flapping configuration for different types of birds with reference to the weight. His research was a masterpiece and he presented the results at scientific forums. For the first time the world came to know about the beautiful research work relating to flapping kinematics, hovering flights, gliding and soaring, power requirements of the flight including the establishment of drag coefficients for zero lift birds. The most important conclusion concerning bird flight for a flapping wing dynamics was: If an animal like a bird has to fly, aerodynamic efficiency and power have to be combined with structural strength and muscular 36

Peof. Satish Dhawan Commemoration Lecture energy, and the weight must be kept at a minimum. Birds are the most biologically successful group of animals that have ever existed. The song birds are particularly successful survivors because of their great maneuverability in flight. Prof. Satish Dhawan was well known as a researcher in boundary layer Address for Correspondence phenomena in subsonic and supersonic regions. And he was also well A P J Abdul Kalam known for experimental aerodynamics. This expertise combined with his President of India love for nature, particularly birds, resulted in a book called “Bird flight”. Rashtrapati Bhavan Prof. Dhawan's work has created a human dream of having a flying New Delhi system with flapping wings. Definitely in a decade, flapping wing aircraft will fly with high maneuverability. 37

Peof. Satish Dhawan Commemoration Lecture learnt by studying bird flight. Dhawan’s book is a systematic and comprehensive treatise on bird What it Takes to Fly flight and will serve as a valuable source book on the subject for years to come. The book brings S P Govinda Raju together hard to get information on topics like bird anatomy, kinematics of bird flight, muscle How Birds fly metabolism, aerodynamics and flight mechanics of Satish Dhawan soaring and powered flight. National Book Trust Price Rs. 40/-, 2002. Birds are well adapted for life in the air as they have evolved over time special features transforming Bird flight is a subject of much interest to them into efficient flight vehicles. These include a aeronautical engineers. Pioneers of flight like Otto strong and lightweight skeleton, aerodynamically Lilienthal, George Caley and the Wright brothers efficient wings with feathers for lift and thrust, observed the flight of birds carefully and drew powerful muscles to power the wing and a fast inferences of value to their work of constructing response control system to stabilize and navigate manned flight vehicles. There is considerable the unstable configuration. The book considers interest even today in the subject as the possibilities these in section 2. It is interesting to note that the of micro air vehicles is being investigated with larger bones of birds are hollow with supporting vigour and there are still useful lessons that can be struts inside (to stabilize their thin walls), thus learnt by studying bird flight. Dhawan’s book is a improving their strength-weight ratio. The wings of systematic and comprehensive treatise on bird birds have profiles which resemble, in a general flight and will serve as a valuable source book on way, those used on aircraft. They were studied for the subject for years to come. The book brings guidance in constructing airplane wings in the early together hard to get information on topics like bird days of aeronautics. Bird’s wings are rather thin and anatomy, kinematics of bird flight, muscle misled aviation pioneers (who did not understand metabolism, aerodynamics and flight mechanics of scale effect) into believing that aircraft should have soaring and powered flight. thin wings for efficient flight. Modern aircraft have much thicker wings often reaching 18% of their Bird flight is a subject of much interest to chord and are more efficient aerodynamically. One aeronautical engineers. Pioneers of flight like Otto may further note that birds as flying machines are Lilienthal, George Caley and the Wright rothers inherently unstable and are actively controlled in observed the flight of birds carefully and drew flight. This enhances aerodynamic efficiency and inferences of value to their work of constructing maneuverability during flight. This feature has manned flight vehicles. There is considerable been incorporated in some of the latest combat interest even today in the subject as the possibilities aircraft. of micro air vehicles is being investigated with vigour and there are still useful lessons that can be Section 3 is devoted to a study of the kinematics of wing motion in powered flight including take off 38

Peof. Satish Dhawan Commemoration Lecture and landing as well as soaring. This is supported by Section 6 is devoted to the consideration of bird’s some original material in the form of high speed muscles as power plants. Birds not only need steady photographs of different birds in Appendix C. power for sustaining level flight, but also peak While the main features of wing motion in cruise power for short periods for takeoff or for escaping and soaring are fairly well understood, there is from predators. Like other animals, birds generate much that is not clear in terms of details of motion power through two metabolic pathways (one and their influence on aerodynamic forces in the aerobic and the other non-aerobic) and the muscle take-off and landing phases of flight. In these is thus a hybrid power plant. On the whole, bird’s phases of flight relatively large aerodynamic forces muscles are as thermodynamically efficient as are demanded which the flight speed of the bird is aircraft engines and this is reflected in some birds small. Consequently large flapping motions of the achieving a range of about 2000 kms, which is wings are required. Further study of bird flight comparable with that of typical transport aircraft as appears to be necessary in this context and this indicated in section 7. Section 8 discusses scale presents a challenging opportunity to researchers in effects which are important in understanding the this area. limits for the sizes of birds and their performance. Section 4 is an introduction to the aerodynamics of In conclusion, it is clear that the book is so bird flight. Dhawan explains in simple terms the extensive in coverage and so deep in insight that a production of lift and thrust by the flapping wings small review like this cannot do justice to the work. of a bird in steady flight. He explains how the fast Afull study of the book is strongly recommended. moving outboard sections of the wing contribute to thrust if their orientation (incidence) is properly S P Govindaraju, Department of Aerospace phased with the flapping motion. This section is an Engineering, Indian Institute of Science, introduction to aerodynamics and will be Bangalore 560 012, India particularly useful to those who are new to the subject. It leads on to the construction of a full flight mechanical model of a bird in steady flight including hover. Section 5 deals with this and also explains soaring flight in thermals and shear winds. It is interesting to note here that Dhawan discusses the concept of stability of the flight path of a bird flying below its ‘best glide’ speed. At these speeds, a small decrease in flight speed results in an increase of drag which further tends to reduce the flight speed leading to a runaway situation resulting in stall. This phenomenon has its counterpart in the flight of fixed wing airplanes and is important during their landing. 39

Peof. Satish Dhawan Commemoration Lecture Launching the First Indian Satellite Radio Talk recorded on January 16, 1975 1. On the outskirts of Bangalore near a small village called Peenya there is an industrial estate for electronics and related activities. A visitor entering the first set of buildings on the estate will find the place humming with rather unusual activity. In one of the rooms with super-clean atmosphere engineers and scientists of the Indian Space Research Organisation – called ‘ISRO’ for short – are busy working on what appears to be a large blue and violet diamond like object. This strange structure is a spacecraft with 26 faces, nearly 1½ metres in diameter and a little less in height, about 350 kg the Satellite, designed and built in India by ISRO is shortly to be placed in orbit around the Earth by a Soviet Rocket launcher. 2. In the talk I want to tell you something about the background how the Satellite project came about – how the Satellite was designed and what we hope to learn from it when it goes into outer space. The Indian Space Programme began about 14 years ago when Dr. Homi Bhabha and Dr. Vikram Sarabhai recognised that our country with its excellent intellectual and natural resources could not afford to ignore the utilisation of the potential benefits from the spectacular and remarkable developments in Space Science & Technology. Thus the Thumba Equatorial Rocket Launching Station was established in 1963 to explore the upper atmosphere and ionosphere with sounding rockets. Such scientific studies have an important bearing on the understanding of meteorological and ionosphere phenomenon – both of which have relevance to our country’s weather forecasting and radio-communications. 3. Since then our space activities have grown steadily and today we are well on the way to build our own rockets and satellites. The technology involved is very complex and demands a high degree of sophistication in a number of fields such as electronics, materials and chemicals, rocket propulsion, satellite technology, control and guidance system, etc. The chief objective of our programme is to make use of Space Science & Technology for national development. So we have selected to concentrate on those applications where satellites have a unique and specially large scale contribution to make. Specifically, these applications are in the areas of mass communications for the entire country, especially the rural areas, Reproduced from Prof. S. Dhawan’s Articles, Papers and Lectures (November 1966 to December 1994), (ISRO’s Special Publication, July 1997) (Courtesy : ISRO, Bangalore 40

Peof. Satish Dhawan Commemoration Lecture and in the survey and management of natural resources. Listeners are no doubt aware that the extension of telegraph, telephone, radio – not to speak of television facilities – to all parts of our country, especially the Duraland backward regions, are still a long way off. Similarly, to survey the forest, agricultural, soil and mineral wealth of even one state using conventional methods takes many years. One of the most remarkable things about Satellites is that they make it possible for communications to be established – virtually instantly – over vast areas of the globe. Also, cameras on space platforms looking down towards the earth can see virtually entire continents, detect land and water features, snow cover, cloud and storm movement and relay instantly the information to stations on the ground for practical use. 4. It is obvious that if we want to use satellites for such useful purpose we must be able to build them and place them in space. Here we come across some inherent difficulties – of technology, of resources and the like. To place a satellite into orbit one requires multistage rockets. These are not only extremely complex technologically but also expensive and, unfortunately, their military possibilities make everyone highly secretive. Thus we have to learn to do things the hard way, i.e., by ourselves. Of course, in the long run, this is not bad since it generates self-confidence and self-reliance – which in the final analysis are essential for any national task. On an analysis of the situation a few years ago we found that our scientist and engineers could design and build satellites earlier than the large rocket boosters necessary to launch them. This is especially so because the information on scientific satellites is more open and several of our scientists have been engaged in the study of advanced scientific subjects such as cosmic rays, Xray, and radio astronomy and also because the relatively rapid strides that have been made in recent years in India in electronics. In comparison, information on rocket technology is much more restricted. Thus it came about that when in 1972 the USSR Academy of Sciences offered us assistances to launch an Indian made satellite with a Soviet rocket – the Indian Scientific Satellite Project came into being. 5. So much for the background – now a few words about how the satellite was built. The task was assigned to Prof . U.R. Rao – of the Physical Research Laboratory in Ahmedabad. Prof. Rao also heads the Satellite Systems Divisions of the Vikram Sarabhai Space Centre in Trivandrum. Getting together a band of enthusiastic and bright young engineers, the Project enlisted the active cooperation of the Electronic and Aircraft establishments and Industries in Bangalore and was well on its way within six months of start. 6. A satellite has to operate under rather extreme envirormental conditions. In outer space there is practically hard vacuum with high temperatures when the sun’s rays fall on the spacecraft and extreme cold when it is in the shadow of the earth. In order to ensure proper functioning of different instruments and sub- systems it is necessary to restrict the temperature changes inside the satellite to more moderate values. On the Indian Scientific Satellite this is achieved by passive thermal control system using special paints with the requisite emissivity and absorption characteristics. During the launch phase, the satellite and all its instruments and sub-systems are subjected to severe vibration and acceleration loads. In order to achieve high reliability every component of the satellite has to undergo a series of special tests. Some of the test facilities did not exist in India and the project team had to devise and build those along with the satellite itself. 41

Peof. Satish Dhawan Commemoration Lecture 7. The primary objectives of the Satellite Project were: (1) To conduct worthwhile scientific experiments in space and (2) To build indigenous capability in satellite technology. The flight mode of the satellite – i.e., the one which will go into space, was preceded by the construction of several prototypes each with a definite objective to prove a particular aspect of the final design. Thus the mechanical prototype provided the shape, size and configuration of the structure – the multifaceted diamond shape. The mechanical prototype has also been tested for compatibility with the Soviet Rocket which will launch the satellite. The electrical prototype qualified all the electronic and electrical systems. These include the power supply which is a combination of Silicon Solar Cells and Nickel Cadmium batteries. The blue-violet silicon cells – there are some 18,500 of them – mounted on the outside surfaces directly convert the Sun’s energy into electricity. During orbit when the satellite is eclipsed from the Sun by the Earth the Nickel Cadmium batteries switch on and continue the supply of power – they get charged in turn when the satellite is in sunlight again. The electrical prototype has been flown at Sriharikota suspended from a helicopter to check out the compatibility of the telemetry and telecommand systems between the satellite and the ground station. 8. The satellite when launched is expected to be in a near circular orbit of 600 km height at an inclination of 51 to the equator. Each orbit around the earth will be completed in 93 minutes. The satellite will pass over India for about three orbits every day each orbit taking only a few minutes. In order to enhance the amount of data a tape recorder on the satellite will store the information over a longer period and then on command from the ground station at Sriharikota on the east coast of India near Madras, the information will be relayed rapidly – at 10 times the recording speed – to the ground. 9. In order that the satellite keeps its orientation in space a spin-up system keeps it rotating like a top. Moving through space the rotation of the satellite would gradually decrease because of magnetic fields and drag. Six spherical titanium bottles in the lower shell of the satellite filled with nitrogen at high pressure and connected to reaction jets – somewhat like a rotating lawn sprinkler – spin up the spacecraft periodically on command from the ground. The orientation of the axis of the spinning satellite in orbit is determined by special sensors – two of these called magnetometers determine the direction of the earth’s magnetic field – somewhat like a compass – and the third a Solar Sensor, measures the angle of the spin axis with respect to the Sun-Satellite line. The directions determined are accurate to about one degree. 10. There are three scientific experiments on the satellite. All three have been designed and built by Indian Scientists. The first experiment is on X-ray astronomy and is being conducted by Prof. U R Rao who also directs the Satellite project. This experiment will detect a measure X-radiation from stars in our galaxy known as the Milky Way. It will also seek information on X-ray sources outside the galaxy. With a bit of 42

Peof. Satish Dhawan Commemoration Lecture luck Prof. Rao hopes to find some new X-ray sources. The second scientific experiment on solar physics has been developed by Prof. Daniels and his group of the Tata Institute of Fundamental Research. This experiment is concerned with the processes that go on inside the Sun. In particular, the experiment aims to detect the emission of high energy neutrons and gamma-rays at times of violent solar activity called solar flares. The third scientific experiment, relating to Aeronomy, is being conducted by Prof. Satya Prakash and his group of the Physical Research Laboratory using electron traps and ultraviolet detectors the experiments seek data on the heat balance in the ionosphere and particle flux and other information in the equatorial latitudes. 11. Once the satellite is in orbit the only link with it for receiving information is through the Ground Telemetry & Telecommand Stations. The main station at Sriharikota has a steerable antenna – called a Yagi Array – and equipment for receiving the telemetry signals from the satellites, processing them and displaying them quickly from the state of health of the satellite can be judged. A tracking network gives the satellite position and its movement in orbit. From the station, radio commands can be transmitted to the satellite to carry out various operations. In all, 35 types of commands can be executed. Asecond ground station has been set up near Moscow in cooperation with the SovietAcademy of Sciences. To further increase the data coverage a third telemetry station in Toulouse in France will receive data and send it to the Project team. During the launch, and afterwards, information from the ground stations will be continuously flowing via communication links to Peenya where the Mission Control Centre of the project has been established. The critical phase of launch operations occurs in the period about a week before and about a week after the time of launching. During this period the engineers and scientists at the launching pad, the ground stations and the mission control centre have to be continuously in touch to exchange information and confirm that everything on the satellite as well as on the rocket and the ground stations is in working order. The check lists run into literally hundreds of items. The Peenya Mission Control Center and the Launch Station in the USSR will be linked through direct links which will make two way telephone & teleprinter communication possible. 12. The flight model of the satellite and the ground stations are now complete and are undergoing the final round of checks and tests. In less than two months the satellite will be airlifted to a cosmodrome in the Soviet Union and another series of intensive tests conducted. The Indian Project Director and his Soviet counterpart will then set the precise date and time of launch and the first Indian Satellite will be in orbit around the earth – a culmination of intense effort by a dedicated team and an important step in India’s effort at harnessing space for national development. Jai Hind 43

Peof. Satish Dhawan Commemoration Lecture Satish Dhawan 1920 - 2002 Satish Dhawan, who was director of the Indian Institute of Science and human problems, a characteristic that today is called (IISc), chairman of the Indian Space Commission and the Indian “leadership quality.” I usually hate using terms like this to Space Research Organization (ISRO), and president of the Indian pigeonhole a person, but here it fits. Satish could be tough without Academy of Sciences, received his engineering degree from Caltech having to get mad first- a trait that I envy. He was a natural mentor for in 1949, his PhD in aeronautics in 1951, and a Distinguished Alumni younger people. Finally, he had a very good sense of humor, a quality Award in 1969. He returned to Caltech as a visiting professor in 1971- that I think is necessary, but not sufficient, to keep one from becoming 72, when he reportedly asked to delay Indira Ghandi’s summons to pompous in old age. I still remember our Ping-Pong games in the lab. return home to head the ISRO until his course was finished. Hans When Satish won, he would crack: “See, I am a crafty Asiatic!” Liepmann, Theodore von Kármán Professor of Aeronautics, Emeritus, was his thesis adviser. Anatol Roshko (now Theodore von Kármán Professor of Aeronautics, Emeritus), Satish, and I worked together on a problem in Remembering Satish Dhawan shockwave–boundarylayer interaction. This was Satish’s first participation in active research. It was a marvelous time! Almost by H a n s L i e p m a n n everything we touched was new and exciting. Our equipment was modest, even for the standards of the time, but with some ingenuity it In January 2002, Satish Dhawan, my friend for more than half a could be made competitive; this was an additional stimulus. The three century, whose personality and friendship had an important and of us worked easily and well together and laid the foundation for our lasting effect on me and my understanding of India, died at his home in lasting friendship over the next half century. After this work was done, Bangalore, India. Roddam Narasimha (Caltech PhD ’61, Satish started his thesis work on the direct measurement of skin Distinguished Alumni Award ’86), also a professor at the Indian friction. This was actually a classical problem in low-speed flow of Institute of Science, has written a complete and beautiful history of both fundamental and direct technical importance. The aim of Dhawan’s life, the man and his contributions to society—a story so Satish’s effort was the development of a new technique capable of well presented and complete that there is little I could have added to it, making similar measurements in supersonic flow possible. It was the even at a time when I was a great deal younger and a better writer beginning of a lasting research effort and a great success. In addition, than now, in my 89th year. All I can add are a few reminiscences of our Satish cooperated with Anatol on the design and construction of an first meeting and our work together—a time for which there exist now ingenious flexible nozzle for our research in supersonic flows-another few living witnesses—and glimpses of our contacts over all these example of ingenuity substituting for large amounts of grant money. years. Finally bureaucracy intervened, and Satish had to return to India in I have often mused about the bifurcation points in one’s life, the times such a hurry that he could not even finish the introduction to this when a small and sometimes even unwelcome choice of alternatives thesis, which, like any good researcher, he had left to be done last. So I results in major changes in one’s future. One of these bifurcations (in, finished it for him, which led to a funny incident: One faculty member I believe, 1946) resulted in my meeting Satish Dhawan. I wrote about reading the rough draft of the thesis called me up complaining that in the occasion a number of years ago in a memoir. the introduction Satish had not acknowledged me as his thesis supervisor. So I had to add a remark to this effect. After the report Ernie Sechler, one of the original members of the GALCIT (Graduate came out, it happened that the great Sir Geoffrey Taylor visited Aeronautical Laboratory of the California Institute of Technology) GALCIT, and I showed him Satish’s work. He happened to have a faculty, was an excellent engineer, but his most outstanding quality in leaking fountain pen with him and managed to make a spot on the title my opinion was an uncanny feeling for the potential of students. Ernie page. I asked him to sign the spot with his name and send the signed handled the graduate admissions. Looking back now, I realize that on report to Satish. I wonder what became of it. every occasion where we disagreed on potential student behavior and performance, he was right and I was wrong. In 1964, I took my family with me for a term at the Indian Institute of Science. It was certainly no accident that Bangalore was the only Sometime in the mid-’40s, I worked with two Indian graduate students place for me to spend a term away from my many years at Caltech. It (both, I believe, from upper-crust, wealthy backgrounds) with whom I was not nearly as easy to get there as now. Bangalore had not yet could not work well. They both seemed to have a reluctance to developed into the Silicon Valley of India. We got stranded for a few perform the sometimes unpleasant and boring chores necessary in days in Delhi, and the long-distance telephone worked only experimental research. I was, of course, not stupid enough to consider sporadically. At this time Satish had been director of IISc for only a this a general characteristic of Indians, but I felt that perhaps the few years, but the place was already humming, full of young, eager select group that came to Caltech from India had prejudices against students and obviously endowed with a new confidence in the future. manual labor and essential, but not highly intellectual and We lived on the campus. Some evenings Satish would come to our glamorous, routines. In any case, I told Ernie that I’d like a rest from “hutment,” and the two of us would walk around the campus and talk Indian students. about anything that we considered a university should do and be. At other times we gathered together in the director’s place for tea in the Within days he called me with the news that he had a new student from evening, where we learned much about Indian life and aspirations. India who wanted to work with me. At first I wouldn’t even agree to Nalini, Satish’s wife, we met there for the first time, and she and their come down to the second floor to talk to the student, but Ernie insisted, children became part of our extended family. I know now enough of and knowing him and his instincts about students, I finally did walk university life and problems to realize how immensely difficult it was downstairs, where I met Satish Dhawan. Later he was to become the for Satish at his young age to reform time-honored curricula and director of the Indian Institute of Science in Bangalore, the Indian professor-student interaction, and to instill the self-confidence institution probably closest in scope and aim to Caltech. Ever since necessary to reach for new research vistas. That he succeeded beyond then, we in GALCIT have had close contacts with the Indian Institute all expectations was evident to me on my later, shorter trips to of Science, and thus a calibration station for admissions, leading to Bangalore. some excellent Indian graduate students at GALCIT. Many years ago Satish told me that accurate weather prediction could Satish did join my research group, and it soon became evident that we improve India’s economy decisively. With the flock of satellites he had acquired an outstanding new member. From his previous helped organize, Satish did indeed do something about the weather. scholastic records, we expected excellence in scholarship and class Now future geophysical satellites will be launched from the Satish work, but there was so much more. Satish was immediately accepted Dhawan Space Center, named in his honor last September. and respected by this highly competent and proud group of young scientists. He showed an unusual maturity in judging both scientific 44

For Private Circulation Only! Free Distribution among WCRC Members/Well Wishers/Students! Not for Sale! https://factordaily.com/satish-dhawan-birthday-space-center/ Prof. Satish Dhawan Birth Centenary Celebrations (1920-2020) Courtesy: 1. Selected Articles on Prof. Satish Dhawan re-printed with permission from the Indian Academy of Sciences Publication ‘Resonance’ Vol. 8, No. 10, Oct – 2003 2. Padma Shri Prof. R.M.Vasagam who have initiated Prof. Satish Dhawan Commemoration Lectures with support from ISRO and he was Instrumental for organising Prof. Satish Dhawan Commemoration Lectures at IEI, Karnataka State Centre, India 3. Padma Bhushan. Dr. K. Radhakrishnan, Chairman of Space Commission, Secretary of the Department of Space and Chairman of ISRO (November 2009 and December 2014) 4. The Institution of Engineers (India)-IEI, Karnataka State Centre, Dr. B. R. Ambedkar Veedhi, Bangalore - 560 001, Karnataka, India 5. https://www.youtube.com/watch?v=5kX8IEgnbbY 6. https://www.youtube.com/watch?v=6TNrzDPsYDw 7. https://www.youtube.com/watch?v=8krHsJcYfxs 8. https://www.youtube.com/watch?v=AdCnjz0o8bc 9. https://www.youtube.com/watch?v=MJI7VSyvMHQ 10. https://www.youtube.com/watch?v=66IJVhzbzBg 11. https://www.youtube.com/watch?v=8krHsJcYfxs 12. https://www.youtube.com/watch?v=7MocowV8RXc 13. https://www.youtube.com/watch?v=zuZNLr6M19o 14. https://www.youtube.com/watch?v=U1k5YR8-MM4 15. https://www.youtube.com/watch?v=PGqnhphBNNc&t=1s