 Welcome back everybody to the second lecture of this course on rocket and space craft propulsion. So, yesterday we discussed what are rockets, what are the different applications of the rockets and where are they used. Before proceeding further, first let us look at a little bit of history of rockets. The invention of rocket was actually older than the aircrafts engines and it all started with the invention of gun powder or black powder by Chinese sometime in 9th century. Actually the Chinese alchemists were searching for the exhilarate of life and by mixing some concoction or other, they came up with black powder which is an explosive which can be burned in a control manner and that started the development of rockets. So, this was initially an accidental discovery, but then the Chinese realized in potential and started experimenting with it for different applications including many military applications like development of bombs, cannons, then fire arrows, the rocket propelled fire arrows etcetera. So, the first use of rockets actually where apart from some fire crackers and all was for military applications and the first recorded use of rocket in battle gets back to as far back as 1232 AD when the Chinese used the rockets against the Mongol huts at Kaifeng Fu. Now, one of the earliest text which mentioned the use of rockets was Huolong Jing, which was written by a Chinese artillery officer Jiawu in as far back as mid 14th century. So, as you can see that it is quite old as a practical application. Now, in this text he mentions the use of first known multistage rocket as well. So, multistage rocket is not something unique Chinese have already thought about it had used it and the fire dragon issuing from the water that is what they used to call the multistage rocket. It was mostly used by Chinese navy and they had a profound impact on the geopolitical history. Now, after the Chinese after the China was taken over by Mongols and during the Mongol wars or the Mongol invasion the Mongols took this rocket to Europe. So, rocket technology was first known to Europeans by the invasion of Genghis Khan and Ogary Khan because they conquered part of Russia, Eastern and Central Europe and they used rockets also to their advantage particularly for military application. But till that time the casing of the rockets were usually wooden or bamboo or paper something like that and for about 200 300 years it remained like that it was essentially just used as a military weapon but with not much of advancement in its technology. But by 1792 we see the rocket reappear in its more refined form in iron cases and this was successfully developed by Hyder Ali of Karnataka of Mysore and his son Tipu Sultan. So, Tipu Sultan and Hyder Ali started using this iron case rockets and initially they were very very effective because they used to scare the cavalry of Britishers or their adversaries because a fireball coming towards the horses, horses used to get scared. So, they were more efficient than the cannons and they used it during the Anglo-Mysore wars quite extensively. But there was a massive flaw in this rockets and that is accuracy or controls because of that it did not have such a profound impact on the war that can change the history. So, therefore, it had the potential but because of its inefficiency and inaccuracies it was not very I would say effectively could be used in a military application. But the Britishers saw the potential of it and they took then active interest in this technology to further develop it. And the Mysore rocket of that period were much more advanced than the what the Britishers have seen before. So, therefore, they took a keen interest on that and primarily the advancement was because of the use of iron tubes for holding the propellants. So, first of all by that you can pack in more propellant burn longer and burn without burning the entire body because if you are using bamboo then it is a chance that if you put more propellant it will start to burn the body instead of providing the propellant propulsive force. But using the iron tubes you are essentially able to provide thrust in the intended direction by not burning out the body. So, this use of iron tubes enabled them to get higher thrust and also the longer range. These rockets were capable of going up to 2 kilometer that was huge in that period we are talking about 18th century. But after Tipu Sultan was defeated and captured this Mysore rockets were influential in British rocket development. And this were inspiration for the development of congrieved rocket which we are going to talk about later which the congrieved rocket. So, after this say 1792 is what where we see the rockets emerging again in the iron tube and Napoleon wars were sometime at about 1815. So, about 2025 years there was a massive development and from that point onward particularly in the Napoleonic wars we see rockets having a substantial influence on the outcome of the war because now the accuracy have improved and they are now much more effective. So, as I have just said that the Britishers took keen interest in Tipu Sultan's iron case rockets and one person who was in the forefront of his development was William congrieved. He was an officer in British East India Army and after he saw the use of this rockets by Tipu Sultan's forces he started researching on the original design of this Mysore rockets. These rockets were called Mysore rockets as you can see there are some pictures here of the Mysore rockets. Now he essentially started a I would say scientific program in development of this rocket technology as a viable technology for military applications. So, he started a vigorous development program at the Arsenal's laboratory. He prepared new propellant mixtures which can provide the higher thrust and larger range. He developed a rocket motor with strong iron tube and with conical nose this is another development having a conical nose that reduces the drag. This early concave rocket weighed about 15 kg 14.5 kg 32 pounds which again was quite substantial if you are talking about in early 19th century and the Royal Arsenal's first demonstration of the solid fuel rocket was in 1805. So, essentially the beginning of solid fuel rockets are can be considered to be 1805 when it was first demonstrated. These rockets were effectively used in the Napoleonic war and the war of 1812. Now, based on his experiences with the development of this rocket technology congrieved actually published three books on rocketry. So, there has been substantial improvement, but once again starting from say 1800 which is early 19th century till the beginning of 20th century there were not much of substantial development in the rocket technology it remained where it was. So, the early rockets if you look at still they were very inaccurate. They had a strong tendency to veer sharply of their intended course because there were no control and stability they were in unstable. The early Mysore rockets and their success are the British congrieved rockets reduce this instability somewhat by attaching a long stick to the end of the rocket. As you can see here there are long sticks added for stability, but still they were not able to remove this drawback completely. And if you look at those rockets they look very similar to the firecrackers the bottle rockets that are kids used nowadays. Now, essentially by putting this stick what they are doing is they are making it so stable that it is difficult for the rocket to veer out of the course, but still the accuracy or I would say marksmanship of the rocket has not improved. The accuracy problem was greatly improved nowadays most of the rockets the thrust is slightly vectored and by doing so it produces an off axis force which then spins the rocket particularly is useful for missiles it spins the rockets and provides the stability. So, this slight thrust vectoring or off axis thrusts causes the rocket to spin along its axis when it travels. So, it travels like a bullet because it is spinning so it has more stability. So, the hail rocket actually removes the need for a rocket stick and because of that its overall surface area reduced. So, the overall frictional force is reduced so they were able to travel further the range was increased and were more accurate. So, as what we are seeing now that the coming of control technology into rocket slowly. Now, let us now come to the modern day rockets and space flight. The modern day rocket development started at the early 20th century and after that actually if you look at the history of modern day rocket whatever was proposed by the pioneers I will come to the pioneers in 1903 to 1905 or 1915 still we are following the same. We have not done any new invention all the basic principles were proposed at that time and formulated at that time rocket technology still works on those principles. So, that was the golden era of rocket science starting from the beginning of 20th century till about 10 15 years. So, beginning of 20th century there was a burst of scientific investigation particularly into interplanetary travel and this interest was largely due to the science fiction books written by Jules H. G. Wells where they talked about going to moon or people coming from Mars etcetera etcetera. So, traveling long distances or interplanetary travels become a passion became a passion for that generation and that started the actual scientific development. So, far when we talk about rocket science essential is where all practical applications that if you put this is going to happen like that, but there are no theoretical foundation for rocket science. Now, in the beginning of 20th century the rocket science started to emerge with a strong theoretical basis. So, the pioneer of mathematical rocket science can be said to be Konstantin Soikovsky. He was a math teacher in Russia and he essentially first wrote a book titled The Exploration of Cosmic Space by means of reaction devices and there he formulated the full principle of rocket propulsion. So, therefore, this can be considered to be the first serious scientific work on space travel. He proposed the Soikovsky rocket equation which essentially are the principles that govern rocket propulsion and is named in his honor, but actually it was not proposed by him or developed by him, but it was named in his order because this was I would say the development of this rocket equation was an ongoing work. So, many many researchers were actually involved in that, but the final equations were then honored named after him in his honor because he had profound impact on the development of rocket science. Not only that we are looking at 1903 or 1905. So, more than 100 years back he advocated the use of liquid hydrogen and liquid oxygen that means cryogenic rocket which actually came into being sometime in 1960s. So, about 60 years before they actually were used he proposed the use of liquid hydrogen and liquid oxygen and this proposal was not out of thin air. He actually did calculations and showed how efficient this type of fuels will be in rocket propulsion. So, therefore, he first proposed the cryogenic propellant and he calculated their maximum exhaust velocity. So, essentially he calculated the specific impulse produced by cryogenic fuels. His however, his work was essentially unknown outside the Soviet Union and, but inside Soviet Union he was inspired he had inspired a generation of rocket scientists and if I look history of development of rocket science substantial development had happened in Soviet Union and the present day Russia and most of that work was inspired and following Sokolovsky's work and they inspired the research in rockets experimentation and for and also it inspired the formation of society of studies of interplanetary travel in 1924 as back as in 1924. So, but the point is that although he has formulated many things it was quite unknown outside Soviet Union because of that there were parallel developments outside because the physical principle remains same. So, many people at particularly are talking about the golden age of science where they were all stalwart present everywhere. So, many people started to think alike and that is what happened in rocket science also. He proposed something there were people outside Soviet Union working independently proposed the same. So, one such person was Robert Asnold Paltier in 1912 published a lecture on rocket theory and interplanetary travel which looks very similar to what Sokolovsky has proposed. He independently derived Sokolovsky's rocket equation again. So, as we can see here the development was happening in both the places independent of each other nobody knows about other persons contribution and at that time the communications were also not that fast. So, it is take long time for the information to percolate from one place to another. He did basic calculation about the energy required to make round trips to moon and planets and again till date these are the equations we are following for interplanetary travel. He also proposed the use of atomic power that is radium to power a jet drive, but that has still not come into rotation because of some geopolitical issues. But technically it is a very feasible thing because of the fact that nuclear reactors have very high energy density. So, they can produce huge amount of energy and if they can be controlled in a manner that you can exhaust that jet effectively we can produce huge amount of thrust. So, you can go to extreme velocities. Now, next we come to the person called Robert Hutching Goodard. He is named as the father of modern rocket science. He is an American professor, he was a physicist and also a prolific inventor. He is credited with creating and building the world's first liquid fuel rocket and he successfully launched this rocket as you can see there is a picture here at the bottom. He successfully launched this liquid fuel rocket in March 16, 1926. Between 1926 and 1941 his team has launched up to 34 rockets. This rocket achieved altitudes as high as 2.6 kilometer and speeds as high as 885 kilometer per hour. And again we are talking about early part of 20th century and at that time this were massive achievements by any standards and Goodard's work as both theorist as well as an engineer anticipated many of the developments and these developments actually led to the first successful space fight possible. So, many technology which he proposed and patented were actually found application in the real space flight. He had about 214 patents to his credit. So, as I said that he was a prolific inventor. The two most important patents that he had related to rocket science which kind of changed the way rocket science developed was multi-stage rocket design which he patented in 1914 and liquid fuel rocket design also in 1914. These two are regarded as the important milestone towards space flight. So, as again as I am saying that not only the if you look at liquid fuel rocket design it involved the many, many subsystems which he also needed to design the fuel feeding system, the pumping system, the combustor, the nozzle. One of the greatest I would say a proposal that he put forward which made possible again successful flight of rockets was using D. Laval nozzles with rockets the converging diverging D. Laval nozzles. He was the first one to propose it and use it and that allowed the hot gases to be expanded at very high supersonic speed producing large amount of thrust. So, in 1919 he wrote a monograph called a method of reaching extreme altitude and this is considered one of the classic text of 20th century rocket science. It has all the calculations and description of how to achieve extreme speeds and altitude. Not only this he successfully applied three axis control gyroscopes and steerable thrust to rockets to improve their stability and range all of which allow them to be controlled effectively in flight. So, his inventions were also used in flight control. So, actually he was a complete rocket scientist starting from the combustion system to fuel feed system to the stability and control system. He worked on everything and developed full rockets which is a very rare feat because these are different specialties, but he had expertise in all of them that is why he is considered to be the father of rocket science. Now, so this three I have talked about as father there were other people also. Next let me talk about some very important milestones or programs in rocket development. The first one I can think of is the V2 rocket. V2 rockets were developed by Germans during the Second World War. In 1943 the production of V2 rocket began in Germany. This rocket was designed in a German lab in Pina Mundi and Werner von Braun and Walter Donberger. They were the pioneers of this. Their team was involved in the design and development of this rocket. It started somewhere in about 1935 or so and they were able to successfully develop this rocket. It had an operational range of about 300 kilometer. So, they were fired from mainland Europe and they were able to reach England. So, these rockets were actually used in the Second World War. The energy of warhead with an amount of explosive charge. This rocket normed altitude of about 90 kilometer, but if vertically launched it could have achieved up to 206 kilometer. That is quite a bit of range or altitude. This vehicle was essentially I would say the first prototype of modern rockets. This was a solid propellant rocket. The first prototype of modern rockets and it was similar to most modern rockets with turbo pumps, inertial guidance and many other features. It was successfully used, but it was introduced so late in the war as you can see is 1943. The production began that it did not have much of impact on the outcome of the war just like the turbojet engine was introduced so late in the war that by that time the war was almost over. So, it did not have much of impact. But first successful military use of rockets in modern era has opened a flood gate. What happened after the war? All the scientists, German scientists who were working in the German rocket development missions were essentially taken either to USSR or to USF. Werner von Braun and his team were taken to USA. They were rehabilitated in Marshall Space Center in Huntsville, Alabama and they started working on the development of American rocket program. Later on I will come to one of the most successful rocket program Saturn V who was spearheaded by Werner von Braun who was the chief architect of V2 and that was the rocket which put man into moon. So, they started with V2 rocket that is why V2 is a very important milestone in the history of rocket science. Now, after the Second World War we come to the era of Cold War and although that was a very tense period for the world but because of the Cold War the competition between the two super powers particularly the military competition saw a rapid development particularly in the rocket science and space science. So, wherever we are today started from that era where there was massive funding available there were lot of resources put in the rocket science and the space science and because of that there were massive development in every sphere of rocket science. So, very early in the this thing your Cold War in 1950s and 60s by the end of 1950s we already had ICBMs intercontinental ballistic missiles developed. It and this missiles it was realized that they can carry nuclear weapons to very large distances up to about 10,000 kilometer. So, no part of the world was not in the reach of this missiles. So, entire world came under the nuclear crowd because all these missiles were capable of carrying nuclear warheads. So, America and Russia developed arsenals to destroy world many many many times and because of that since both of them had it it worked as a deterrent that is why we never had a third world war. So, but that was the ugly part of it but the other part of it is this ICBMs later on as we will see where the precursors of the space flights. Initially they came as ICBMs which are military used, but very soon they were converted for civilian use and then a different program started for space flight. So, the ICBM launch vehicle such as such as R7 Atlas and Titanium became the delivery platform of choice of this weapons the nuclear warheads, but they also were later converted for space mission and it is continuous till today. So, the development was partly fueled by core war and 1960s became the decade of rapid development of rocket technology where Soviet Union and USA were in the forefront. Soviet Union had the Vostok program, the Soyuz program, the proton rocket program all of them were actually offshoots from their ICBMs. So, we will see that the impact the ICBMs had in the rocket science or the space flight science per se. United States had many experimental program like X-16, X-20, dinosaur aircraft etcetera etcetera plus they started working on the Saturn project also. So, that I will just come to later. There was also significant research in other countries such as Russia, Japan, Australia and India about that time India also entered the club. ISRO was started sometime in 1960s and this started we started our own indigenous rocket program starting from very small sounding rockets and we have come a long way in Chandrayaan. So, that 1960s was the era when the rapid development in rocket science started and that essentially then grew to be in space exploration. And we had successfully by the end of the 1960s successfully man landed in moon and also now we have already achieved the unmanned mass exploration there is a plan to put man in Mars also in near future by 2020. But or the genesis of all of this lies in the Cold War development of ICBMs. So, now let us look at again some other milestone program Sputnik program by Russians. Sputnik was the first artificial satellite to be put into Earth's orbit. This is the Sputnik satellite. It was launched into an elliptical low earth orbit by Soviet Union on October 4th 1957. Some say that the launch of Sputnik because the Americans were taken by surprise when Sputnik was launched and they were very very panicky. So, during that time they also started massive investment in their space program and then that lead to because at that time Americans vote to put man in moon in 10 years and they successfully achieved it. Now, coming to the launch vehicle because that is the focus of this course. This is the launch vehicle which is a two stage R7 Samyorka. This as I just said was initially designed as an ICBM by B1 that was organization that designed it. So, again you see that ICBM converted to a launch vehicle. So, first satellite launch was done by an ICBM. So, and repeatedly Russians have done that many many of their launches very important launches were on converted ICBMs because they did not have a separated civilian and military rocket program unlike the Americans. American had separated program. NASA was completely on space and department of defense was completely on defense production, but Russians did not have the separate program. So, they used the military vehicles for launch. Now, another milestone Yuri Gagarin Yuri Alexevich Gagarin was the first was a Soviet pilot and cosmonaut and he was the first human to journey into outer space. So, here is a picture of Yuri Gagarin. This is the module in which he went to outer space when his Vostok spacecraft completed an orbit of the earth on 12th April 1961. So, the first manned flight to space was in 1961 and once again the spacecraft Vostok. Let me just go back to the list of ICBMs. Vostok was also an ICBM as you can see here. So, Vostok was also an ICBM converted for space flight. So, once again we see that the military use being converted to civilian use and with profound effect on the development of science and technology. So, one of the space milestone was Gagarin going to outer space. Then we come to another very important program. This program was by NASA Saturn V. Now, Saturn V was an American human rated expendable rocket. It was used by NASA for all their Apollo missions as well as in the Skylab Skylab program started something about in 1967 until 73. It was a multi-stage liquid fuel rocket. NASA launched as many as 13 Saturns and with no loss of crew or payload with Saturns. They were very successful rocket. It still remains the tallest, heaviest and most powerful rocket ever brought to operational status and still holds the record for the heaviest launch vehicle payload. It was a huge rocket. Still the models are there in the Kennedy Space Center as well as the NASA Marshal Space Sensor in Huntsville. This rocket was again the chief architect of that is Werner von Braun. The scientist would develop the V2 rocket. So, this so far is the biggest rocket ever built. The largest production model of Saturn family of rockets, the Saturn V was designed under the direction of Werner von Braun and Arthur Rudolf at the Marshall Space Flight Center in Huntsville, Alabama and it has a very successful student as a launch vehicle. Repeatedly it was used without any glitch. Now, one of the most important missions taken by Saturn rocket program was the Apollo mission. Apollo program was the space flight effort carried out by NASA that landed the first humans on earth's moon. It was conceived during Eisenhower's as the president, but after the Sputnik launch by Russians, it got the steam particularly under President JF Kennedy because JF Kennedy proposed the national goal of landing a man on the moon and returning him safely to the earth. This was proposed in 1960s and in 1961 in his address to the Congress and he promised that it will be done within 10 years and it was achieved by 1969. So, within 10 years NASA was successful in fulfilling that promise and putting a man on moon. So, the Kennedy the Kennedy's goal was accomplished with the Apollo 11 mission. So, Apollo started from Apollo 1. There was various missions going to outer space not to moon, but in Apollo 11 the astronauts Neil Armstrong and Buzz Aldrin landed their lunar module. Here is a picture of the lunar module on the moon on 20th of July 1969 and they walked on the surface. While, Michel Collins remained in the lunar orbit in the command spacecraft is the lunar orbit. This is the assembly of lunar orbit. This is the Saturn V rocket launching the lunar module and this is the full assembly full picture of the system of various subsystems of the entire mission. So, they landed on the surface of moon and then successfully came back. The three then safely landed back on earth on July 24th. So, that as Neil Armstrong has famously quoted a small step for man and giant step for mankind putting somebody in the surface of moon. After that there were few five subsequent Apollo missions which also landed astronauts on moon. The last one in December 1972 and in this space flight 12 man walked on moon. After 1972 the Apollo mission was scrapped and after that so till date nobody has ever landed on moon. Now the interesting part of history is that during the Apollo development of Apollo mission Russians were also in the race. They were also trying to put man on moon, but since Americans have done before that before them they stop that program. So, they never tried to put man on moon. So, for after 1972 nobody has landed on moon. I think India has planned sometime in 2015 or something to have a manned mission to moon that is in Chandrayaan too right, but that is a collaborative mission between India and Russians. Now another very important rocket program was Soyuz program. This was the main warhouse of Russian space program the Soyuz rocket. Soyuz is a family of expandable launch system. This was developed by Okb-1. It was manufactured by TSSKB Progress in Smarer Russia. This launch vehicle is the most frequently used launch vehicle in the world. Still date it has the maximum number of missions. The Soyuz vehicle are used as the launcher for the manned Soyuz spacecraft as part of the Soyuz program of course as well as for launch of unmanned progress supply spacecraft to the international space station and for commercial launches that is commercial launches of satellites from different countries. Soyuz rockets uses RP-1 and liquid oxygen as the propellant. So far this is considered to be the most widely used rocket in the world. So it is still operational still it sends supply to the international space station using Soyuz rockets. Now another very important space program is the American space shuttle program. The space shuttle was a partially reusable launch system and also an orbital spacecraft operated by NASA for human spaceflight missions. So this essentially the it was a vehicle mounted on a rocket and then it worked as a rocket vehicle. It was used extensively of course now it has stopped in 2011 the program was stopped. This system had a combined rocket launch orbital spacecraft is a rocket launch as you can see the picture of the rocket. This is the space shuttle sitting on this and reentry space plane with modular add-ons. So it is a very I would say versatile program with it was so much there was so much flexibility in this program that many many things can be done in space shuttle and the basic structure was same and it was to a large extent reusable particularly this module was reusable the reentry space plane. Now it was used for total of 135 missions spanning almost 30 years started in 1981 till 2011 30 years it was operate this program was operational participated in 135 missions. The major missions taken by space shuttle includes the launching of numerous satellites interplanetary probes Sassini, Galileo these are all launched by space shuttle program which are now gone beyond the solar system. The Hubble space telescope was launched by space shuttle then they were very extensively used in space science experiments because they should have even scientist on board who is to conduct experiments in space. And also they were extensively involved in the construction of the international space station which I will come to next and also servicing of international space station. The space shuttle at launch consisted of the orbital vehicle the external tank two solid rocket boosters as you can see here it was launched vertically like a conventional rocket with thrust from the two side the side boosters and three main engines and then in the edge of the outer space the actual space shuttle vehicle will take over. However, this program has faced two of the most talked about space tragedies first one you can see here the picture of challenger challenger disaster challenger was a space shuttle operation and no this was challenger first one was challenger second one was challenger yeah this is a challenger disaster yeah this is columbia so this is challenger disaster where the entire system particularly it started from the solid rocket boosters the SRBs it had nothing to do with the space shuttle this thing per se the solid rocket boosters exploded in 73 seconds into the flight it just took off and it exploded in flight. So, you can see a picture of the entire the explosion happening and all the astronauts on board were killed and another equally I would say a black spot in the space exploration is the columbia disaster is shown here where the columbia space shuttle is broken into pieces this was during the re-entry it fulfilled its mission when it was coming back there was some problem with the head shields and the entire vehicle was broken into pieces and the all the astronauts on board were killed including Kalpana Chawla. So, but even after the columbia disaster the space shuttle program continued for few years, but now in 2011 they have stopped the space shuttle program, but again this was a major program and a major milestone in space program. Now the next international space station this is a collaborative effort between various countries like the American, Russians, Japanese, Europeans and Canadians this is a habitable artificial satellite in low earth orbit it follows the Salute, Alma, Skylab and Meade stations and this is the ninth space station to be inhibited by human beings it has a modular structure whose first component when they have been launched by American space shuttles as well as Russian proton and surge rockets once again proton was an ICBM. So, as you can see that Russians very successfully use their ICBM for various space applications. So, it is a joint project between five participating space agencies international space station was intended to be a laboratory, observatory and factory in space. It is also planned to provide transportation, maintenance and act as the staging base for possible future missions far into far off places like moon and mars and also asteroids. So, this will be the launching pad for further space missions. Now, coming to the Indian's perspectives ISRO is was established in 1969 proposed by the visionary like Vikram Saravai and Satish Dhawan led. So, starting from the early days of the first successful endeavour taken up by ISRO was Aryavatta first Indian satellite which was launched by Russians because at that time we did not have launch vehicles. Then the launch vehicle program successful launch vehicle program started with first was sounding lock rockets which is to go to pretty low altitude then SLV satellite launch vehicle program which is to send Rohini class satellites to lower torbids. Then came the PSLV program porous satellite launch vehicle very successful program till date had many successful missions and this is the power horse for Chenrayaan this is a picture of the Chenrayaan India lunar mission and it has successfully send the rover to moon and now they are planning this Chenrayaan 2 which is supposed to be a manned mission. So, PSLV is now the war horse for ISRO most of their successful missions are with PSLV and the next is GSLV Geosynchronous Launch Vehicle which is supposed to be capable of putting headlight into 36000 kilometer orbit Geosynchronous orbit which uses a cryogenic stage. PSLV is primary initial stage solid and then liquid GSLV has a cryogenic stage as well. So, this is the Indian space program as under ISRO ISRO and like in America the civilian and military applications of space is under two different entities in India. So, ISRO is for the civilian side primary goal is to develop launch vehicles and putting satellites where the military side we have DRDO different research and development organization which has an integrated guided missile development program IGMP DP started long time back sometime in late 70s early 80s under the leadership of Dr. A. P. J. Abdul Kalam and they have successfully developed many many missile systems. There are some pictures first one is Agni Agni is so far an IR next day we will to go beyond 5000 kilometer will be ICBM. So, Agni is the the longest range missile developed by India successfully test fired many times. Another very successful missile is Prithvi which is shown here Prithvi is a small range ballistic missile and Prithvi has been put for multiple uses including as a missile interceptor this is a Prithvi missile interceptor. So, it is part of Indian development of Indian missile shield Prithvi missile is being used as the interceptor. Apart from that there are other missiles which are developed by DRDO one such missile is Akash which is shown here is a surface to air missile typically an anti aircraft missile then NAG is shown here this is the anti tank missile where you have a high energy explosive at the tip of it and this one is Prithvi again a surface to air missile. So, I have shown some of them there is also PINACA there is also some submarine launch missiles etcetera which I have not shown here, but India is now in the top league of space exploration as well as in the missile programs because we have achieved almost 90 percent of what others have already done. So, we are very close there. So, one of the Indian success story is it is rocket program either we talk about missiles or in space the success story is in the rocket program unlike most other programs which have failed or still continuing this is a successful endeavor taken up by India. So, we stop here we talked about the history of rockets today then next then we come to now the actual theoretical formulation talk about rocket propulsion next. Thank you.