 Hello everyone. Good afternoon. People with good internet connection. Yes, you can turn on your video. Hello Mohan. It has been a long time. Yeah, yeah. Okay. So, if you turn on the video, it feels more interactive. When you nod your head, yes, no. No, I will feel better. So, if you have good internet connection, any moderate dust code is sufficient. You can turn on your video. Good to see you all back. I am good. I am good. Yeah, regarding the material by end of the session, it will be attached to you. Oh, hello for you. Yeah, space and astrophysics lesson. It will be attached to the YouTube link as well as your telegram channels. You can download it. Good. Okay. Hope your prelims preparation is going on well. You have around a month and few days remaining. Yes, yes. Good. Oh, hello Lakshmi Raja, everyone. Mahesh were. Yes, yes. Good afternoon. So, even though we were on online mode, I am able to recollect all of your names. Mahesh are from batch or beacon batch. Lakshmi Raja, Haisal, you are here for the offline class for one or two classes, correct? Yeah, yeah. Good. Okay. So, today's session, I'll give you a out sketch. How we are going to progress with the today's session. We have thoroughly discussed about space science and astrophysics in our first five or six classes. So, this is going to be like a update. Any current of us that has happened in the last five or six months after our classes were over, those are the things we are going to update in today's class. And also it will be like a quick revision session. Since it's a live session, many people are watching. It may be their first time for that reason. We'll have quick revision of important topics and then update to the GS class topics. That's how it's going to be. Good. Okay. The first ever mission that we discussed in space science, do you remember? The Aditya Alvan mission. We were discussing about different layers of the sun, starting with different layers and regions of the sun. What were the different layers? It has around six layers and six regions. The core region, the center most part of the sun, it was called as core. And then we had a radiative zone and then the convective zone. These three layers, they're not visible to us because of the extreme brightness of the sun. And then coming to the other parts, something called as photosphere, the first visible layer. And then we have chromosphere and the outermost layer, that is corona, the solar corona, where temperature drastically increases all of a sudden. And we said the sun has lot of sunspots, regions of high magnetic activity. I showed you a few pictures where sun will have high magnetic activity because of pressure. The two characteristics of sunspots. First, the sunspots are relatively cooler spots. The temperature compared to rest of the areas of sun, the sunspots have cool or comparatively cooler. And then sunspots are regions of high magnetic activity. They have extremely high amount of magnetic activity and most important of all, the sunspots, they generally originate at higher latitude. And then it slowly shifts towards the equator. Altogether the solar cycle, it takes around 11 years. Right now we are in solar cycle 25. I told you the sun goes from solar minima. Minimum activity to solar maxima. And then again it drops to solar minima. So solar minima to maxima and maxima to minima. That marks one complete solar cycle. It takes 11 years on an average. And right now we are in solar cycle 25 that started in the year 2019, December, almost 2020. Which means we can expect the solar maximum somewhere in the year 2025 in the middle of the solar cycle. Good. Now coming to the helios physics missions. The missions that tries to study about the sun. I gave you a lengthy list out of which one of the upcoming mission in impact important mission, Aditya L1. India's first solar mission. Correct? I told you Aditya L1 will have a spacecraft that is placed at the point L1 Lagrangia point 1. What is mean by Lagrangia point 1? Going back to Newton's law of gravity. So the region where the gravity is balanced. The gravity of sun and the gravity of earth. It is balanced at certain points. There are totally 5 Lagrangia points out of which we are going to utilize Lagrangia point 1 L1. The main reason for placing this spacecraft here is we can have a complete view. There would not be an occultation, there would not be any eclipses. That is the reason we chose L1. L2 is present on back side of the earth not useful. L3 is present on other side of the sun again cannot be utilized. L4 and L5 it has meteoritic activity because of that that is ruled out. Now the location of L1. L1 is located 1.5 million kilometer away from the earth on an average from the surface of earth. L1 is located 1.5 million kilometers away from the earth. Okay. So was there any update about Aditya L1? Yes. One update. Post March. The mechanism by which the coronal mass ejection. Can you recollect the concept of coronal mass ejection CME? What is coronal mass ejection? Where stream of hot ionized particles and highly magnetized particles. The sun is not a calm star even though we call it as a low dwarf. The sun is smaller in size on a universal scale. It's a smaller star. It's called as a low dwarf but it's not calm. It keeps on emitting hot ionized and hot magnetized particles. So they are called as coronal mass ejections. A type of solar particle event. We discussed about the impacts that coronal mass ejection may cause. What are the impacts? First it affects space-based services. For example, communication satellites, navigation satellites and also power grids. All these will be affected when the coronal mass ejection reaches the earth. Since they are highly magnetized, since they are highly ionized, they can affect our electronic instruments as well as any space-based services. So we have been looking for a method to predict coronal mass ejection. Good. The default mechanism that we used it was called Cactus. Cactus, this was the default mechanism wherein we have developed a new mechanism. First, the first mechanism is cactus. Computer aided CME tracking software. This was the algorithm. This was the type of software that we have been using to predict the coronal mass ejection. And right now there is advanced version. Okay. Now India has developed a mechanism called Cisco. C-I-I-S-C-U. Cisco. CME identification inner solar corona. CME identification inner solar corona. Keep in mind these are not instruments. These are type of algorithms that we use on supercomputers so that we can predict the coronal mass ejection. This is indigenously developed in India. That's why it's important. And this has been developed by people in Aaribata Research Institute for Observational Sciences. You can write down the abbreviation alone. When you receive the document, you can go through the expansion. Aaribata Research Institute of Observational Sciences. Aries. Scientists in Aries, they have developed this particular mechanism, Cisco. Okay. Coming to the next one about Mercury. What are the few key facts that we have to remember about Mercury? Mercury is the smallest planet in the solar system, correct? Because we shrunk the solar system. Pluto is no more part of the solar system. So Mercury is the smallest plant in the solar system with low specific heat capacity. I told you Mercury has stocking temperature range. On the sun-facing side, it goes up to 230 degrees Celsius. Where on the other side, it goes up to 180 degrees Celsius. It heats up faster. It cools down slower. The main reason is there is no atmosphere on Mercury. Mercury has a thin exosphere, extremely thin layer of air. For that reason, Mercury will heat up faster and Mercury will cool down faster. Heats up faster, cools down faster. Now, important missions related to Mercury, we specifically told. So far, only USA has sent the missions to Mercury. Also keep in mind, we are not considering fly-by missions. In the beginning of the class, I told you what are the type of spacecraft. We were talking about fly-by spacecraft. What's a fly-by spacecraft? Imagine there is object here, let's say a planet or a moon. If a spacecraft is going to pass through this, making observation, we don't count it as a mission to the particular orbit or a particular object because this is just observing as it passes by. So, these are fly-by spacecrafts. The trajectory never captured in orbit of a planet or a moon. For that reason, this is just fly-by spacecraft. Fly-by spacecraft missions are not counted because voyage or many other missions, they have passed Mercury. We are not considering fly-by spacecrafts. We are considering only orbiters, landers and rovers, the three prominent type of spacecrafts. So, in that case, Merina and then Messenger 10. These were the two orbiters that were sent to Mercury and both of them were by NASA. The mission lifetime is over. Both of them are not active right now. What is baby Colombo? Wevin is asking, also, Karthik is on point, baby Colombo, the latest mission by JAXA and European Space Agency. Yes, yes, yes. We are talking about, I'm about to tell this. So far, only NASA has sent missions to Mercury and have succeeded. Wevin, there is an ongoing mission, a mission that is traveling to Mercury. That's called as baby Colombo, a mission by European Space Agency and Japanese Aerospace Exploration Agency. Not to be confused with NASA. No, NASA is not part of the third mission. This is the first non-American mission that's traveling to Mercury right now. Okay, next. Now, I told you there will be two spacecrafts. One spacecraft that will be making inner orbit and one spacecraft that will be making a highly eccentric orbit. The first one I told you the name is Beppi and the second one was called Mio. Can you recollect? Beppi Mio, Beppi by European Space Agency and Mio by Japanese Aerospace Exploration Agency. That's that's how we discussed when we were discussing in the class. Yeah, please hold on. Yeah, there's alternative name for Beppi. It's called Mercury Planetary Orbiter, Mercury Planetary Orbiter, MPO, the exact technical name for Beppi. So, if at all you get it in question, don't confuse this as some other mission. MPO Mercury Planetary Orbiter is nothing but the Beppi. The other one is Mio, Mercury Magnetospheric Orbiter, Mercury Magnetospheric Orbiter. It's called as Mio. Mio is by Japanese Aerospace Exploration Agency and Mercury Planetary Orbiter. Also called as Beppi. It's by European Space Agency. Done. Other than this, there is one more update. One more Space Agency. All these happened after your GS classes were over. Right now there is one more plan from Russia going to launch a mission called Mercury P. This is going to be a lander. This is planned by Roskamos, the Russian Space Agency. So, what is this Mercury P? P means Posatka. Russian Posatka means lander. It's going to land. If this is successful, this would be the first Mercury lander. The first ever spacecraft to land on surface of Mercury. This is a planned mission. Done. Okay. Next. We're going to talk about approximately how long it takes to reach Mercury. Someone has asked around at least seven years because this was launched in 2018. They're expecting it to reach by year 2026. Seven to eight years approximately. Okay. Next. About Venus. What are the special things that we have discussed about Venus? First thing, it's hottest plant in the solar system. Correct? Compared to all other planets, Venus is the hottest planet in the solar system because of something called as a runaway greenhouse gas effect. We discussed two major factors that leads to higher temperature of Venus. The first one, Albedo. On an average, the Albedo is around 0.7. Close to 70 percent of the light is reflected back from the surface of Venus. The incoming radiation, it will be shortwave radiation. That is insulation. Incoming radiation from Sun. It will be shortwave radiation wherein the outgoing radiation, it will be long wave. Terrestrial radiation. This will be long wave radiation. If you see, first thing, it will reflect at least 70 percent of the light. Fact number one. And factor number two, it has thick layer of carbon dioxide. So, it's filled with carbon dioxide in the atmosphere. For these two reasons, altogether contributes to runaway greenhouse gas effect where there is more insulation but lesser terrestrial radiation because of the temperature goes up to 270 degrees Celsius, we have discussed. Yeah. And now there is update. We discussed about important things like phosphine that is discovered on Venus. I told you. Phosphine, which is a biomarker. Phosphine. Phosphine has one phosphorus and three hydrogen atoms. For the people who are watching this on live stream on open source mode, you may not understand exactly what's mean by phosphine. I have given it in the material. At the end of the class, you will be able to download the material. So, these are the topics which we have extensively discussed for the GSB people. You can access it through the notes. Phosphine is discovered on atmosphere of the Venus. So, this phosphine is marked as is considered to be a biomarker. It is discovered on outermost atmosphere of the Venus. Yes. Now, update number one. Two missions. Since phosphine is considered to be a biomarker, since the biomarker is discovered on Venus, right now USA is planning for two more missions. Da Vinci and Veritas. Two missions. Da Vinci and Veritas. So, what is Da Vinci? What is Veritas? Keep in mind, this is going to take a long time. This will be launched around 2028 up to 2030. In these two years of window, it will be launched, the optimum launch window 2028 or 30. It is going to be another seven or eight years. So, Da Vinci is a deep atmosphere Venus investigation of noble gases, chemistry and imaging and the next spacecraft, Veritas means Venus emissivity, radio science, INSAR. Can you recollect INSAR, synthetic aperture radar, INSAR topography and spectroscope? You do not have to write the entire expansion. You can write on the spacecraft name alone. Da Vinci and Veritas. A few information about Da Vinci and Veritas. First, Da Vinci will have two components. First, it will have a flyby and then it will have a atmospheric spacecraft. Can you remember atmospheric spacecraft? You can compare it with the Cassini-Huygens mission, a spacecraft subsystem that will descend in the atmosphere. Yeah, it will descend through the atmosphere and it will study about the atmosphere. Da Vinci will have two components. A flyby and atmospheric descent probe. What is the purpose of sending atmospheric probe? First, important thing. It is going to capture high resolution picture of a landform. A high resolution picture of landform, this particular landform. This is called as tessere. Tessere. So, what is this tessere landform? This is comparable with continents on the earth. This landform, it appears similar to the continents that are present on earth, which means right now we are intrigued. We are interested in knowing if Venus is having tectonic activity. So, the past missions they have captured a blurred picture of tessere. This Da Vinci mission, it will be capturing high resolution image of this landform. Yeah, Arun has updated. So, there was a recent report in Hindu saying phosphine need not be considered as biomarker. It can be because of volcanic activity also. Yes, that is a possibility. That is what we are going to study. See, when we were teaching about this phosphine part in the Venus, I particularly told you, this is not the first time that phosphine is discovered on some other planet, earlier Saturn and Jupiter, two other planets where phosphine was discovered. But we ruled out the possibility of having life here because they do not have lithosphere. There is no solid land layer on the top. It is considered to be the Jovian planet or gaseous planet. And it is purely because of geological activity. They clearly said this is purely because of geological activity. Now, we cannot consider the similar thing with respect to Venus because Venus, as I told you, the outermost atmosphere, the outer layer of atmosphere, it has earth like temperature. So, there is still a doubt if it could be because of any acid-loving bacteria. Is there any type of geochemistry or is there any type of photochemistry going on here? This is just a doubt. And also keep in mind, the phosphine, it is not directly observed. The prediction of phosphine is based on previous scientific studies. Right now, two different opinions. First, it could be a biomarker. Second, it could be emitted because of geological activity like volcanoes. Yes, even on Venus, it could be because of geological activity like volcanoes. There is still a chance. We have to follow up the news, clear? Harum Sir, can we go to the next one? Yeah. So, about Darwinian ratas, I told you, Darwinians will have two spacecrafts. And it is going to capture photograph of tesserae. Now, coming to veritas, the key word is here. Synthetic aperture radar. This carries a radar. Veritas, it carries a radar. What is the purpose of carrying a radar? So, it is going to create a three-dimensional image of Venus topography. I am going to capture the three-dimensional image of Venus topography. The main reason we are sending radar instead of optical instrument, I told you, Venus is extremely bright. It is impossible to do a visual observation. For that reason, we are sending radar, which will be firing microwaves and radio waves so that we can reconstruct. You can compare this with the RISAT satellite of India. Can you recollect? It is a radar imaging satellite that generally sends microwaves. And when the microwave bounces back, it will reconstruct what is present on the ground, 3D simulation. Yeah. In a similar way, veritas, it will be constructing a 3D layer of the topography of Venus. This is the idea. Also, I forgot to tell one more thing related to Venus. Venus landing. So, when we were discussing in class, we were talking about a lander called veritas, correct? Veritas by USSR that landed on Venus, the only lander. It is actually the only lander series. I forgot to mention it actually. Veritas 1 to veritas 13. Back then, the space program by USSR was excellent. So, right now it is waning because of lack of funding, corruption and different activities. But generally, this is the first spacecraft that landed on other planet, the veritas 1 to 13. 13 spacecraft, they attempted to land on Venus. And veritas 13, it survived for 2 hours, the highest by any spacecraft on the surface of Venus. Why? First, temperature, extremely high amount of temperature and extremely high amount of pressure. Because of these two reasons, most of the veritas were failure. They lost contact almost instantly after landing up, wherein this was the longest survivor, veritas 13. So, keep in mind, USSR has attempted to land close to, oh sorry, not veritas, venera. I misspelled it. Yeah, yeah. Who corrected it? Cynthia. Yeah, yeah, thank you. It is not veritas, it is venera. I am still in the veritas hangover. Venera, venera 1 to venera 13. 13 landers that were landed on the surface of Venus by USSR. Keep in mind, so far, USA has not landed any spacecraft on the surface of Venus. Yes. Next, one more upcoming mission, other than veritas and da Vinci. There is a mission called N-Vision, the first Venusian mission by European Space Agency, the partnership between European Space Agency and NASA. Why NASA is here? NASA is going to provide radar. Very lesser information about the mission, but still, European Space Agency and NASA, wherein the radar will be provided by NASA. Are people able to see the video clearly? A few people have messaged that the video is not working properly. Paisal, Mohan sir, is it clear? Yeah, yeah. Okay. So, Anish, try to reconnect it now. It could be a network problem on your side. Please try to reconnect. Yeah. Coming to the next one, related to Mars. Yes, all the Martian missions, they have a massive update after our classes were over. Some of the important Martian missions to remember, we started with the Mars Exploration Rover, correct, M-E-R, Mars Exploration Rover that contained two rovers, Spirit and Opportunity. This is a completed mission. They are not active anymore. And then comes the Curiosity Rover. Curiosity Rover, it is functional right now. Curiosity Rover, it is operating on the Mars right now. It landed in a location called Gale Crater. Can you recollect? Gale Crater. Spirit landed in Meridian Iplanum, Opportunity landed in Yusef Crater, wherein this landed on Gale Crater. And then, Insight, Insight mission by NASA. This is also active. This is completed, wherein these two missions are right now active. And coming to the most recent missions, three important missions, also our Mars Orbiter mission, the Mangalyan mission by India. This is also active, no doubt. Mars Orbiter mission, it is active. Yeah, done. Now, coming to the most recent missions, the missions that were sent in 2020. First, let us start with the Perseverance Rover. Now, before that we will start with Tianwen. I said NASA was considered to be the king of Martian landing because they made nine successful landings, including the Perseverance Rover. NASA has made nine successful landings on the surface of Mars. They have placed their spacecraft on the surface of Mars, which is considered to be a major advancement, wherein China, China they sent three components together. Can you recollect the three components, lander, rover, and orbiter? When your GS classes were going on, this was on its way. This was scheduled to land somewhere in February, March. Yes. The orbiter, lander, and rover, the rover is called Zurong, named behind the Chinese folk god of fire, Zurong. Now, the recent update is Tianwen is a successful mission. The orbiter, it is orbiting properly. The lander, as per the expectation, it landed properly and also it deployed the rover that is called Zurong. Zurong, it made a few test runs for few hundred meters. It drove on the surface of Mars. Everything is functioning properly, which means after USA, China is the only country that has put spacecraft on the surface of Mars, which includes both the lander and rover. One major scientific achievement by China, the only country to place a three type of spacecraft on a single mission on Mars. This is China, clear? Okay. Now, coming to the perseverance rover mission, what is the update? Perseverance is also successful. Can you recall the type of landing that perseverance was supposed to handle? It was not supposed to crash land. Instead, NASA had a jet-controlled descent technique. It is called sky crane technique. I even showed you a video where it is a jet-controlled descent vehicle, where there will be a controlled descent, jet-controlled descent, a technique to land spacecraft on the surface without any impact. Yeah, next. This is also called a sky crane technique. Sky crane technique. This was successfully performed and right now, perseverance is operating on the surface of Mars. All the three missions are the perseverance rover, Tianwen and Allamal mission. All the three missions that were launched in 2020, they are successful. Done. You could see the size of our rovers. This is easily recollect. Sojourner, curiosity rover and here comes the perseverance rover. Keep in mind, this is the largest rover and the heaviest rover ever landed on Mars compared to Tianwen or any other rovers. Perseverance is the largest rover on the surface of Mars, which is operating right now. Yeah, bungee jump like technique. It handled the seven minutes of terror going from 19,800 kilometer per second to a standstill in seven minutes. This was perfectly handled by the sky crane technique and perseverance rover is successful. Now, coming to the other update, we were talking about a helicopter like device, a rotor, a rotor craft named as ingenuity. Yes, this ingenuity it successfully took off. It flew for a few meters on the surface of Mars. So, this is just a picture taken from perseverance rover. This has successfully took off, hovered for some time and then it landed and right now it has made around 11 successful flights. The first powered flight on other planet, keep this in mind, ingenuity. The first powered flight on other planet. This is basically like flying a drone on other planet. The first powered flight on other planet. What else is special about ingenuity? Now, let us take the atmosphere of earth and let us take the atmosphere of Mars. When you compare these two, Mars atmosphere is much thinner. It is just 1 percent as dense as earth's atmosphere. Keep this in mind. Density of Martian atmosphere, it is extremely thin. It is around 1 percent compared to earth's atmospheric density. What is implication? What it has to do with ingenuity? Keep in mind. If a vehicle has to ascend it, the rotors has to spin, correct? If you see our car engines, for example, if you are going to switch on your car, maximum the RPM, the revolution per minute will be somewhere between 800 to 1000. If you are going to accelerate, it will shoot up to 2000 RPM, a normal car engine. If you are going to do a normal shift, okay? So, similarly all the helicopters and everything it will have few thousand RPM, wherein if you have to ascend a helicopter like vehicle on the surface of Mars, then it is going to take more effort. So, this might look like a normal takeoff. Keep in mind it was rotating at a rate of 6000 RPM because of lesser density, okay? The RPM, it has to go up to 6000 RPM. Main reason I am saying is the overall outcome of this particular idea is density of Mars is much lesser. It is filled with carbon dioxide. The density of Martian atmosphere is much lesser compared to density of earth's atmosphere. Clear? Okay. Anbu, they are saying to zoom in correctly on the screen, they are not able to see it. They are going to zoom in on the screen. Many of them are looking at the mobile device, right? Give me a moment. We will just zoom into the screen so that it will be easy to view. Yeah. Is this sufficient? Okay. Abhishek is asking if the density is less, it is easy to take off, right? No. If the density is less, how do you push down more air? It is going to be difficult. When the rotor is spinning, it cannot push down more air. When the density is less, it is going to be difficult. Next. Important device, MOXI, a device that converted carbon dioxide into oxygen. This was sent in the Perseverance Rover and it has successfully demonstrated. This is a technology demonstration mission because the roadmap of Martian missions, it is mapped with, you know, manned missions. So, if we are going to send astronauts to the Mars, how we are going to send them oxygen? Method one, yes, we can pack a lot of oxygen and then we can send them through the spacecraft. Method number two, we may be able to convert carbon dioxide present on the Mars into oxygen. It is achieved using a device called MOXI. The device name is MOXI. It attempted to convert carbon dioxide to oxygen, which was successful. Mars oxygen in situ resource utilization experiment. The expansion is not needed. Mars oxygen extraction in situ experiment. Overall, it attempted to convert and it produced around 10 grams of oxygen. This is just a technology demonstration mission. They may be amplifying the size of machine and slowly they may be producing oxygen on the surface of Mars. That is the idea. Mars oxygen in situ resource utilization experiment. Clear? All right. Coming to the next one, HOPE's Mars, HOPE Mars mission also called as AL AMAL mission. This was also en route when the classes were going on. So, this has also achieved successful Martian orbit insertion. This is also a successful mission. Done. We will go to the next one. Yeah. Next. Update about lunar missions. So, we thoroughly discussed about Chandrayaan 1, Chandrayaan 2 and at any cost, you should not forget Changi mission. Changi is the mission by China. We discussed about three Chinese missions, Changi 3, Changi 4 and Changi 5. What is special about these missions? First, Changi 3 deployed the first Chinese rover called U2. Okay. Now, coming to Changi 4, what is special about Changi 4? It landed on far side of the moon for the first spacecraft that soft landed on far side of the moon and it sent pictures of the far side. Yes, it landed in Aitken basin where in coming to Changi 5, after 44 years, Changi 5 collected lunar samples. Can you recollect? The last time that Earth received lunar samples were in 1974 by lunar 24 mission. This was a Soviet mission and after 44 years in 2020, Changi 5, it collected, it drilled samples and it returned back to Earth. So, these three important missions. Now, coming to two upcoming missions. First, lunar polar exploration mission. Yeah, this is 1976, sorry, 44 years, 1976. Last time that lunar samples were returned to Earth, it was 1976 by lunar 24 mission and then after 44 years, Changi 5 mission has returned samples. Okay. Now, next one. Lunar polar exploration mission. Also called as LUPEX mission. This is important because this is a partnership between ISRO and Japanese Aerospace Exploration Agency. This will be launched after Sundryan 3. Recently, the partnership is a review and the plan is on. Japan is in partnership with ISRO. Okay. Most likely, it will have two components. It will have a lander and then it will have a rover. When the lander component, it is going to be designed by India and rover system, it is going to be designed by Japan and the launcher is also going to be provided by Japan by the company Nippon mostly. Launcher by Japan, lander by India and again rover by Japan. This is the plan. Next, International Lunar Research Station. A partnership between two communist countries. A partnership between Russia and China. Recently, they have signed agreements. They are planning to construct a permanent lunar station. So, it could be either lander, rover or orbit or anything. This is just a plan that is launched recently. We are yet to receive more updates. But keep in mind, International Lunar Research Station is going to be launched by Russia and China. It will have series of space stations on the surface and or around the orbit. This is the statement provided by them and or or which means there may be orbital or there may not be two systems on the surface and on the orbit. Clear? Next, with respect to Jupiter, we were discussing about a mission called Juno. There is a small correction to the GS class. I thought the Juno is completed. The Juno mission is still active. This was launched in the year 2011. Solar panels, it is exploring Jupiter. Juno mission is still active. A mission by NASA. Juno mission is still active. Done. Similarly, there is going to be one more mission to Jupiter which has been announced recently. It is called Europa Clipper, going to be launched by NASA. Europa Clipper. Europa is one of the moons of Jupiter. Can you recollect the largest moon in the solar system that belongs to Jupiter? Ganymede was the largest moon. Correct? Similarly, there is one more moon called Europa. This Europa Clipper, this is a mission that is going to be launched to Europa, the moon, not the planet. Keep in mind. A mission by NASA. Next, what are the main objectives of the mission? First, so Europa, it has ice shells and ocean. It has surface water, ice shells and ocean, frozen water. So, it is going to check the characteristics of the ice shell and also it is going to check the characteristics of the ocean. Next, most importantly, it is going to study about composition of the ocean and it is going to study about geology of the Europa. Three important aims of the mission, Europa Clipper by NASA. Cynthia Ashoka, yes, this is similar to the juice mission. Can you recollect the mission called juice? Jupiter, icy moons explore a mission by European space agency. Yes, this is similar to the juice mission, but it is not going to explore many moons, but instead it is going to target only one moon, the Europa. Next, update about asteroids. So, what are asteroids? First, the remnants of solar system formation. So, when the solar system formed, few things are turned into planets wherein all the rugged rocks, all the broken rocks, which are irregular in shape, which do not have a hydrostatic equilibrium. Can you recollect the term hydrostatic equilibrium? What is hydrostatic equilibrium? Most of the stars, most of the planets, they are spherical in shape. Why they are spherical in shape? Because there is radiation that is flowing in the outward direction. At the same time, there is gravity that is pushing in the inward direction. So, this balance between gravity and radiation, this causes hydrostatic equilibrium. The main reason why most of the stars, most of the planets are spherical in shape. So, similar to that, asteroids lack hydrostatic equilibrium. So, generally they are irregular in shape. We were discussing about different missions that were sent to the asteroids, but before that, we were talking about the classification of asteroids, correct? Based on the location, we have three types of asteroids. Can you recollect? Asteroids based on location. First, main-built asteroid. Where is the main-built asteroid present? Between Mars and Jupiter, correct? Asteroids located between Mars and Jupiter are called main-built asteroid. And then the asteroids that share orbit with the planet, that is called Trojan asteroids. They do not collide with the planet. Why they do not collide with the planet? They will be located at L4, Lagrangian 0.4 and Lagrangian 0.5. They are generally located at L4 and L5, which means a balanced position. They will be either advancing before the planet or they will be trailing behind the planet. And the third important one, near-earth asteroid. In that, there is a subclassification called potentially hazardous asteroid. So, this is based on location wherein there is one more classification based on composition. Someone from Trichy has a message. It is basically balanced between radiation and gravity. Radiation is the outward push wherein gravity is the inward push. There is one more classification based on composition. This is based on location, depending on where the asteroid is present. If it is present in the main asteroid belt, you call it as main-built asteroid. And then we have Trojans and then we have near-earth asteroid, wherein based on their composition, we have three types. I did not give this data when we were teaching the GS classes. You can take it now. First, C-type, then S-type, then M-type. Based on their composition, it is classified into C-type, S-type and M-type. So, C-type means con-rite, which generally consists of a lot of clay type of material. Then it has clay or silicate rocks. CCC, you can remember, C-type, con-rite, clay or silicate. Then comes the S-type, stony type, which has silicate and also it has nickel and iron. So, mostly filled with silicate, but sometimes it will have nickel and iron. And then the M-type, the metallic type, the major composition is nickel and iron. But these are the three different classifications based on composition. Okay. So, we were discussing about three different missions that were sent to asteroids. Hybrids are 1, hybrids are 2 and oversight is correct. And most of them are near-earth asteroid. So, inside the near-earth asteroid, there is one more sub-classification. You see here, in near-earth asteroid, you have four classifications. So, all these are classification of near-earth asteroid. Keep in mind, this is not related to anything else. This is only near-earth asteroid. Asteroids that are located near the earth. First, there is something called as aetiras. The entire explanation is given in the material you can refer later. Aetiras, they are located inside the earth's orbit, somewhere towards the sun. The green color highlighted portion shows where the generally the asteroids are present. Aetiras, they are present inside the orbit of earth. So, maybe anywhere between sun and earth, you call it as aetiras. And then, if it is present outside the orbit of earth, but within the orbit of Mercury, for example, between the third and fourth planter of the solar system, then you call it as Amars. A-M-O-R-S, Amars. Aetiras, Amars. So, these two type of asteroids, they will not cross the earth. Mostly, they will not cross the earth, wherein the other two types, Apollo and Aetens, based on semi-major and semi-minor axis, we have something called as Aetens. And then, we have something called as Apollo. These two are the most dangerous asteroids, because they are called as earth crosses. You could see here, either they are minor axis or they are major axis. It will cross the earth's path. So, we call it as earth crosses, Apollo and Aetens. These two are called as earth crossers, Amars, A-M-O-R-S, Amars. Position of Amars. Arun, you could see here. Amars, they are present outside the orbit of earth, but inside the orbit of Mars. So, they are between the third planter and fourth planter of the solar system, somewhere between earth and Mars. The green highlighted portion shows where it is present, wherein in all the pictures, the blue color is the orbit of earth. If it is inside the earth's orbit, you call it as aetiras. If it is outside the earth's orbit, you call it as Amars. If it is near to the earth's orbit, if it is going to cross the orbit of earth, you call it as Apollo and Aetens. Clear? Go to the next one. All right. Now, a recent update. 9442 of office. This was considered to be a potentially hazardous asteroid, wherein this has been ruled out for another 100 years. This asteroid is not going to approach closer to earth. It has been removed from the risk list. It has been struck from the risk list. 9442 of office asteroid. It is a nearer asteroid considered to be hazardous. So, what is mean by this risk list? Who maintains this risk list? That is the main reason for putting this here. It is not international astronomical union. Keep in mind. This is maintained by century, a table called century impact risk table. This is a table that mentions list of asteroids that may impact the earth in near time. So, this is maintained by NASA's center. It is called CNOS. You can read the expansion in the material. Century impact table is maintained by CNOS. Center for Near Earth Object Studies. This is maintained by NASA. Center for Near Earth Object Studies. Now, 9442 of office. It has been struck down from the risk list table. Why it has been struck down? Basically, a scientific advancement. They have followed something called as a bi-static observation. Bi-static. What is this bi-static observation? So, basically, they used two different telescopes to monitor the particular asteroid. This is bi-static. You keep the transmitter at one place and a receiver at some other place. So, in this case, the accuracy of reading is going to be high. This is called as bi-static. Bi means two. Bi-static. You are not going to place the transmitter and receiver at the same spot. Instead, you are going to put transmitter at one point and the receiver at one point. This particular mechanism is called as bi-static mechanism. The bi-static experiment was performed to rule out this particular of office asteroid from the century list table. Just keep in mind bi-static. The key word is bi-static, where transmitters and receivers are presented different points. Next, a new peculiar type of object, sensor object. In astrophysics class, we were discussing about asteroids. We have discussed about comets. We have discussed about meteoroids, meteors, meteoroids, everything. Wherein, sensor object is a totally different one because this object is present between Saturn and Jupiter. Most of them, most of them, they are present between Saturn and Jupiter. Wait. Saturn and Uranus. Saturn and Uranus. A small correction, it is between Saturn and Uranus. Most of them, they are present between Saturn and Uranus. So, what is special about this sensor object? First, they exhibit the property of asteroid, comet and planets altogether. They exhibit the property of planets. Sometimes, they exhibit the property of asteroids. Sometimes, they exhibit the property of comets. It is a mysterious class of object for the first time. There are many sensor objects. So, how do we say it as a property of planet, asteroids and comets? First, they orbit around the sun. More like a characteristic of a planet or asteroid. But at the same time, their composition is like comets. Their geology, their composition looks like comets. So, this is a little of everything. When you read about sensor object, you have to read about two things. The first sensor object that was discovered, Chiron. The main reason for putting this name here is Chiron was the first-ever sensor that was discovered way back, before few years. It was 1977. This should not be confused with Chiron. Can you recollect Chiron from GS class? The moon of Pluto. Hydra, Nix, Chiron. Chiron is different. This is moon of Pluto. This is Chiron. Chiron is a sensor object, the first-ever sensor object that was discovered. This is Chiron. And the largest sensor object till date, Chariklo. Chiron and Chariklo. Two names to remember. Sensor object. No, they are not nearer the objects because they are mostly they are located between Saturn and Uranus. They are much far away from the earth. So, they are not classified as nearer the objects. Majority of them, they are between Saturn and Uranus. You can see here. Done? Okay. Charon was moon is the moon of Pluto. Someone, Gautam was asking Pluto. Charon, Hydra, Nix. All these are moons of Pluto. Clear? Next. About ISRO. For a quicker revision, the list of launch vehicles by ISRO. First, legacy launch vehicles. The vehicles that has retired SLV-3, satellite launch vehicle-3. Then we have ASLV, augmented satellite launch vehicle. Both these are legacy vehicles. They are retired. We are in talking about this PSLV, then GSLV Mark II and GSLV Mark III. Did you read about the recent failure of cryogenic engine? Very so, the cryogenic engine failed and the GSAT was unable to be placed in the orbit. Yeah. Next. About sounding rockets. Sounding rockets should come here operational. And then we will talk about reusable launch vehicle technology demonstrator and then scramjet engine. Correct? Okay. In this, why I am writing it right now is the recent failure. The launch vehicle that failed was GSLV Mark II. Keep in mind, only GSLV Mark II and Mark III has cryogenic upper stage. Can you recollect what does mean by cryogenic upper stage? So, highly efficient engine where we use liquid oxygen and liquid hydrogen. Liquid hydrogen is used as fuel, liquid oxygen is used as oxidizer. Hydrogen will exist as liquid only at minus 253 degree Celsius where in oxygen will exist as liquid only at minus 183 degree Celsius. So, we use high energy pumps to pump out liquid oxygen and liquid hydrogen. We store it and then we use it in upper stages of GSLV Mark II and Mark III. GSLV Mark II faced a failure this time, not Mark III because Mark III it has very limited launches. The Chandra and II, it was launched using Mark III. This one failed and the previous failure that was faced by PSLV. 2017, the launch vehicle of India had a failure and after that the first failure is in 2021. So, the launch vehicle that failed in 2017 was PSLV, not to be confused with GSLV. 2017 failure, PSLV, 2021 failure it was GSLV where the cryogenic engine failed. Clear? Can we go to the next one? Is it going to affect our NISAR mission? Ankita is asking, yes, yes, yes. Most likely the NISAR mission, NASA, ISRO, Synthetic Aperture Radar, it will be launched from with a USA launch vehicle since we have faced failures. We are supposed to put 7 or 8 successful missions all together so that we can launch NISAR. Next, small satellite launch vehicle. We were discussing about SSLV, correct? Small satellite launch vehicle, what is the important, why we have small satellite launch vehicle? First of all, it is a sub 110 launch vehicle. We are basically trying to gain a major share in space commerce. You want to send more satellites. We are two important organizations. Can you recollect the two commercial arms of ISRO and Trix Corporation that was established in their 1900s and then we have New Space India Limited that was launched in their 2019. Both of them are incorporated and they are operating in the department of space under the administrative control of department of space and then we have a regulator that is called in space. In space is the regulatory body, NSIL is the commercial arm, Antrix is also the commercial arm wherein NSIL is recently established and it is catering the domestic markets. Now, through NSIL there will be many business that we will have more satellite launches. For that reason we are developing a small satellite launch vehicle. Keep in mind, they reveal the launch capacity of SSLV. It is going to be 500 kilogram. The maximum payload capacity is 500 kilogram. First, second thing it can be used to launch multiple satellites, not just single satellites, multiple satellites. For example, 100 satellites, so 100 satellites each of 5 kilogram. Yes, it is possible. It can launch multiple satellites and most importantly, it can launch to multiple lower orbits. So, in the lower orbit, it can place satellites in different orbits that is idea. It can be switched off reignited and many satellites can be put in different orbits. Hashita is asking what is Al Amal? The Emirate Mars mission is also called as Al Amal. The Hope mission. Hope mission has three names. It is called Hope mission, a little off topic. We had a question here. What is mean by Al Amal? Ma'am, Hope mission is also called as Al Amal mission. Sometimes it is also called as Emirates Mars mission, EMM. All the trees signifies the same thing, clear? So, back to SSLV. Find that kilogram, multiple satellites can be launched and it can be launched to multiple orbits. It can be launched on demand, most importantly. It is going to have low cost. Now, why we are talking about SSLV here? Next, don't forget that the land acquisition part, it is close to completion near the Shri Arikota. Sorry, near Kulasegra Patnam in Tutikorin. The second launch port that is going to be built in Tutikorin in a place called Kulasegra Patnam, so that we don't have to take the dog leg maneuver. Also, keep in mind this launch port, it can launch only SSLV. It cannot launch PSLV or GSLV, clear? Now, there is a similar launch vehicle that is designed in USA. It is called Stardust 1.0. This Stardust, it is the first commercial launch vehicle which is powered by biofuel. Much important. Similar to SSLV, this is a low powered vehicle, but still the first launch vehicle to be powered by a biofuel generates suited for student payloads and budget payloads. Student and budget payloads. Why we are specifically mentioning the student and budget payload here? See the maximum payload capacity, it is just 8 kilograms. 8 kilograms is the payload capacity. Who will build satellites for 8 kilogram? Generally, it will be a technology demonstration satellite which will be generally built by educational institutions or by students. The entire lift off mass is maximum 200 kilogram which means this is one of the lightest launch vehicle. The maximum lift off mass is just 200 kilogram out of which 8 kilogram can be the payload. This is in a way comparable to the SSLV because it is a small scale launch vehicle. Done. Stardust 1.0, the first ever flight by biofuel and the type of biofuel that is used it is not disclosed till. It may be ethanol or it can be any other type of biofuel. I have thoroughly checked the papers, but it is not available. Good. So, if at all there is any update you can update it later. Next. Krishna, can you remember the concept of ocean sat? Who was the partner when we designed the ocean sat? Can you recollect? Yeah, France. France was helping us when we were designing the ocean sat tree. So, similarly, ISRO and French space agency were planning to devise one more satellite which was finalized recently. This is called TRISNA, thermal infrared imaging satellite for high resolution natural resource assessment. Keep in mind this is not a communication satellite. This is a earth observation satellite which will be used for natural resource assessment. Done. So far we have designed two important things. First, mega tropics. A satellite that was designed by India and France to read about the heat exchange in tropics. And also there is one more satellite called satellite with orgos and altimetric measurements satellite. These two satellites were built by India in partnership with France and also two upcoming things. One is the TRISNA, the other one may be CARTOSAT 3. It is said to be confirmed. CARTOSAT 3 may be built by India and France. And this one is confirmed. The feasibility studies are over. India and France are going to construct a satellite called TRISNA. I am unable to confirm if CARTOSAT 3 is renamed as TRISNA. But right now, TRISNA is confirmed. TRISNA is going to be built by India in partnership with France. Clear? Next, Amazonia. About New Space India Limited. The first commercial program of New Space India Limited, it is Amazonia 1. Whose satellite is Amazonia? So, this satellite belongs to Brazil. This is going to be used for remote sensing the Amazon area, the rainforest area. So, that you can check for deforestation. It is used for monitoring deforestation. And along with this, PSLVC 51. The mission is PSLVC 51 by the way. PSLVC 51, it launched few more satellites. First, a satellite called SD-SAT, Satish Dhawan SAT. A private satellite, SD-SAT. This is built by a private organization, the Space Kids India. The same company that built Kalamsat, Kalamsat V2. Space Kids India. Next, three satellites. They were named as Unity SAT. Basically, three academic institutions in Tamil Nadu, they constructed three satellites. All together they named as Unity SAT. Amazonia, SD-SAT, Unity SAT and a satellite by DR-Divo. It is called Sindhu Netra. Sindhu Netra, the overall idea is to track the movement of Navy ships as well as merchant ships. This is for maritime surveillance. Sindhu Netra by DR-Divo. This is for maritime security and surveillance. Next, one more specialty of SD-SAT. There is still a potential to ask this. SD-SAT, it has engraving of our Prime Minister Mr. Narendra Modi to show solidarity to the Atmanirbar initiative. Keep in mind, this is not a government satellite. This is a private satellite built by Space Kids India to show solidarity support. The picture is engraved on top of the satellite. Clear? We will go to the next one. We will talk about Gaggan GPS-Aided Geo-Augmented Navigation System. Can you recollect what is the use of Gaggan? The principle idea is to increase accuracy of GPS because the GPS, it faces severe ionospheric disturbances. Can you recollect the key terms? Severe ionospheric disturbances where radio wave is absorbed in the ionospheric region and because of that, there will be a high inaccuracy. So, this is acceptable for normal usage, wherein for civilian aircraft navigation and everything, the error rate is not acceptable, especially as per the mandate by International Civil Aviation Organization, the Specialized Agency of United Nations, ICAO, the International Civil Aviation Organization. It charts out a few requirements for integrity of the signal. It needs to be error-free, availability of the signal and also most importantly, integrity, availability is required for the signal. So, to cater this, we have a system that can augment, that can basically increase the accuracy of GPS, that is called the Gaggan. GPS-Aided Geo-Augmented Service, I gave you the clear idea on most importantly, this is interoperable, which means it can interoperate with all other satellite-based augmentation systems, SBAS, satellite-based augmentation systems. What is satellite-based augmentation? Using satellite, you are going to augment, you are going to add capacity, you are going to add accuracy to the signal. So, this is interoperable with all other satellite-based augmentation systems. Most importantly, I told you one more fact, Gaggan, developed by India, which is operational right now, this is the only satellite-based augmentation system that serves the equator region, keep this in mind, the only satellite-based augmentation system that operates in equator region. Can you recollect WAAS, Wide Area Augmentation System by USA, Ignorance by European Union, Gaggan by India, then MTSAT by Japan, and then we have Baidu Satellite-Based Augmentation System by China, and this one is newly developed. This is it to be operational, STCM by Russia. I think you would not have written this STCM in your notes, you can add it. STCM belongs to Russia, system for differential corrections and monitoring. It is not at operational, it is being developed by Russia, similar to Gaggan system. Based on Gaggan system, we were discussing about device that could broadcast emergency information to the fisherman. Can someone name the device? A device that could disseminate emergency information about potential fishing zones and all of the details to the fisherman. A device that is developed by Indian National Centre for Ocean Information Services and the Airports Authority of India. I am giving you more clue. A device, just a soapbox type of device in Germany, good, good, good, Germany. Yes, Swathi ma'am is asking what is the full form for STCM? Ma'am, STCM, it is a system for differential corrections and monitoring. It is available in the material, you can refer later. Systems for differential corrections and monitoring, the augmentation system developed by Russia, good. Now, Germany device, that is a major update. A quick revision about how Germany device works. As you could see here, there are no display, there are no speakers on the Germany device. So, how it works? Imagine this is India and shipping vessel is present somewhere around say 100 nautical miles from India. So, in this case, when we have to inform any emergency message, first it will be sent to the Gaggan satellite, that is GSAT 8, 10 and 15. The message will be sent to a Gaggan satellite. The Gaggan satellite, it will be transmitting the data back to the Germany device. So, the Germany device is like a radio receiver. It can read all the broadcasts, correct? This Germany device, it will send the information to the smartphone. The smartphone should have INCOIS app. This is sent using Bluetooth. The message received from the Gaggan satellite, it is transmitted to the cell phones using the Bluetooth and it should have INCOIS app. The smartphone should have INCOIS app, which will decode the message and display in regional languages, around nine regional languages. This was the mechanism. And in main aspect, when we were discussing, we put a criticism because this was only one way communication, correct? This will act only as a broadcasting service where a government can send a message. But the same time, the fisherman cannot communicate back. That was one major criticism that was put forth on the device. But right now, they have upgraded it. Please correct your notes. Right now, it is not one directional. It is upgraded. On a pilot basis, two-way communication is added. Right now, fisherman can communicate back to the office in INCOIS. And also INCOIS is going to have exclusive satellite for this, Gemini. Right now, they are using the satellite from Gaggan. Soon, INCOIS may have an individual satellite exclusively dedicated for Gemini. It is two-way communication device. Keep this in mind. Yeah, relatively average for a general fisherman because this would cost around 9000 rupees, wherein 90% of the cost around 90% of the cost will be taken by the government wherein 10% will be paid by the fisherman. 900 rupees by fisherman and 800 by the government. That was the idea. But right now, the finance setup is still there. But it is a two-way communication. Next, Artica M satellite. Next, we are going to discuss about Artica M. Just two lines is enough for this. So, this is a weather monitoring satellite. Disconnect it. Recording in progress. Recording stopped. Recording in progress. Is it okay now? Can you see the video? Can you hear the audio properly? Yeah, yeah. Okay. Kavya is asking, sir, will the notes you send cover the older topics too? Yes, yes, yes. So, Kavya, that's what took so long. Basically, I've covered everything starting from your GS class till July 31, 2020. The entire current of SPA is covered for both SpaceX and Astrophysics. You can download it. Good. First, Artica M satellite. It's a weather monitoring satellite launched by Russia. What is special about Artica M? See, can you recollect the types of orbits? First, we were talking about polar orbits. Then we were discussing about geostationary Earth orbits and geosynchronous orbit. For a quicker revision, see here. The Earth is here. If the satellite is going to orbit from north to south, you call it as polar orbit. If it's going to have 20 to 30 degree offset, you call it as sunsynchronous. You still call it as polar orbit, but if it's going to traverse exactly in the middle, you call it as sunsynchronous polar orbit. So, the first classification is polar orbit. Next, after this, next we have something called as geosynchronous orbit. It may have a mild tilt, but the only thing is the time period of satellite will be 23 hours and 56 minutes. This is geosynchronous. If the same geosynchronous satellite, if it's going to be placed right above the equator, you call it as geostationary Earth orbit satellite. Correct? Now, this is a polar satellite. In fact, it's going to monitor the Arctic region especially. Keep in mind, it's going to have a highly eccentric path, something like this. So, what is the reason for having a highly eccentric path? This Artica M, it can capture photograph of the Arctic region every 15 to 20 minutes. Right now, there is only one satellite that has been launched. Artica M, the second satellite will be launched in 2023. So, when the two satellites operate together, each of the satellites combined together, they would be able to capture photograph of Arctic in a time gap of 15 to 20 minutes regularly. So, this is to monitor the climate change, continuous observation of Arctic region. Clear? And one more important thing about Artica M. This can transmit distress signals, ships, flights or any person holding a radio device. If they are going to send a distress signal, it will be captured and it will be transmitted to the nearby ground station. There is a particular program. This is important, international cost pass SARSAT program. India is also part of this program, international cost pass SARSAT program where it's a international treaty, where 45 countries are part of it. It's a non-governmental treaty. Keep in mind, many governments are part of it. It's a non-profit intergovernmental, in fact, humanitarian cooperative program. We call it as SAR, satellite aided search and rescue operation. Satellite aided search and rescue SAR. Not to be confused with synthetic aperture data. So, there are many satellites that receive signals for the particular program. So, this Artica M, it can receive distress signals and it can send it to the ground station so that rescue operation can be carried out. This is important. This is not by UN, I repeat. This is not by UN. This is not by any other international organization. It's independent humanitarian program. Artica by which nation? This is by Russia. Abhinav M, this is by Russia. Artica's satellite was launched by Russia. It has dual purpose. First, it can monitor the climate change and also it can receive distress signals and it can help in search and rescue operations. Okay, next. Starlink. The Starlink internet system. Can you recollect the Starlink internet system? Where is it going to be located? Is it in low earth orbit, high earth orbit or medium earth orbit? Can someone say how about the Starlink internet system by SpaceX? A constellation of satellite that's going to provide internet service. Just taking the messages here. Yeah, low earth orbit. Good. A constellation of satellite that will be located at low earth orbit. Somewhere around 550 kilometer above the surface of earth. 550 kilometer above the surface of earth and they'll be providing the internet service. So, we thoroughly discussed about the important advantages and disadvantages. Correct? First advantage, it will have low latency. Second, it has phased array antenna. Phased array antenna, which means it's going to have high transfer speed. Most importantly, it can cover even remote locations. So, visible even to the remote locations, which means even the rural part will get good internet. These are the advantages of having Starlink or satellite-based internet system. And then let's talk about disadvantages. What were the disadvantages which we were discussing? Can you list few disadvantages of satellite-based internet service, especially a system like Starlink? Rafferty notes, okay, space debris, crowding of low earth orbit. Good. Yes, 13,000 satellites. Who's at 13,000? Let me see. Vicky says, sir, we have around 13,000 satellites. Yes, yes, there were around 13,000 satellites. But recently Starlink has submitted proposal to the US FCC, US Federal Communication Commission. They're looking to increase the constellation up to 30,000 satellites, Federal Communication Committee, FCC. Most likely Starlink will have around 30,000 satellites. Now let's talk about disadvantages. First major disadvantage, it's going to affect optical astronomy. Many telescope networks, they have complained. They just see the streak of Starlink satellites passing by. It's seriously obscuring the vision of the universe. Second, it also affects radio astronomy. Because whenever we set up a radio satellite, we just generally put us a radio silent zone where no communication devices or radio devices are allowed. It's totally banned. We have a radio silent zone. But the radio silent zone is breached by Starlink satellites. For example, let's say, let's talk about the square kilometer array. A square kilometer array where for one square kilometer, no radio devices are allowed. Imagine when Starlink is going to pass on the square kilometer array, it's going to beam the signals, radio signals. Ultimately, it's going to affect the observations. So all these are disadvantages. And the most important one, you people were telling about the crowding of low earth orbit. Good. So when the low earth orbit is crowded, most likely it will lead to Kessler syndrome. Kessler syndrome. What is this Kessler syndrome? Kessler was a scientist in NASA. So he gave a theory. Imagine if you are going to crowd the orbit with a lot of satellites, especially the low earth orbit, and then a collision happens. Good. When the first major collision happens, what will happen? Imagine two satellites colliding on each other. When the collision happens, the collision is not going to be a low velocity collision, it's going to be high velocity. Keep in mind, once we cross the earth's atmosphere, there is no friction, there is no atmosphere. The debris, they'll be traveling up to the speed of 10 kilometer per second, a little less than escape velocity of earth. Imagine, 10 kilometer per second, a small paint spec, a small metal piece that's traveling at rate of 10 kilometer per second. So what Kessler syndrome means when there is, when a critical mass is crossed, when you have a lot of objects in the lower orbit, when a first major collision happens, it'll cause a lot of debris, each of them like sharp nails. And this will create a cascading effect. This will create or trigger a chain reaction where all the things present in the particular orbit will be affected. This is called as Kessler syndrome, increased likelihood of collision in a particular orbit. Shortly you can write increased likelihood of collision in a particular orbit after critical mass. Once mass of the satellite exceeds a critical mass, it increases the likelihood of collision. Ultimately the entire orbit will become unusable. This is called as Kessler syndrome. I have given the proper technical definition in the document you can refer it. It's a theoretical scenario. He predicted certain critical mass, but right now many researchers say we have already exceeded critical mass. At any point it may trigger a chain reaction which can lead to more sharpness being produced and entire orbit may become unusable. These are the problems associated with Starlink. Now, let's talk about how we are going to manage space debris. Yes, we thoroughly discussed what means by space debris, the type of rockets which we use, the type of launch vehicle it is called expendable launch vehicles, correct. What is expendable launch vehicle? It can be used only once. The parts are abundant. Once it crosses the atmosphere, it is abundant. So, if this is the earth and if this is the atmosphere, once the launch vehicle is launched, the dead weight is reduced. The fuel tanks, the rocket engines, these are detached. If it is inside the atmosphere, it is going to fall inside and it is going to disintegrate because of the air friction, but if it is going to be outside the atmosphere, once you jettison different parts of the launch vehicle, it is going to orbit around the earth. So, these are called as space debris, basically defunct satellites, detached parts, all these constitutes are space debris. How we are going to monitor, how we are going to monitor, how we are going to tackle space debris? Right now, few important missions, especially in the past three or four months. First, mission ELSA-D by Japanese Aerospace Exploration Agency, important mission. End of life services by Astroscale Demonstration Mission. Mission ELSA-D. Ashwapri is coming to the point. Sir, we have Project Netra. Yes, yes. ISRO has Project Netra where we have around three telescopes and two radars that are actively monitoring space debris. Keep in mind, the Project Netra right now, it has only ground component. That is, we have only terrestrial satellites and terrestrial, sorry, we have only terrestrial telescopes and terrestrial radars wherein these are space-based systems. ELSA-D. First, we will discuss about ELSA-D. So, what is this ELSA-D by Japanese Aerospace Exploration Agency? This is a demonstration mission, repeat. This is a demonstration mission. You could see two components. The first one is called service, the second one is called client. This is around 170 kilogram. You do not have to memorize the figure, this is for understanding wherein this is just 17 kilogram. This particular satellite, it will release the client. Basically, it will create the artificial space debris. This will release the client and then it will capture the client again. So, again it will release the client, it will capture the client again. So, through successive repeated operations, it is just practicing. So, we are learning how to capture the space debris. So, this is a tech demonstration mission. Keep in mind by Japanese Aerospace Exploration Agency. So, this is for target search, target inspection and learning capture mechanism. This is just to test capture mechanism. Search and capture mechanism. Keep in mind this is not collecting any of the space debris. This is creating its own space debris and it is going to collect it clear. Now, coming to the next one. Clear one, clear space one, clear space. So, what is this clear space? First, for the first of a time you could see here a small space debris. In fact, this is not small, this is more than 100 kilogram. It is going to be captured by a spacecraft and it is going to be pushed inside the atmosphere. This is a mission by European Space Agency, clear space one. It is yet to be launched. This is just a simulated image. This is yet to be launched. This is going to use artificial intelligence. Clear space one. Okay. So, European Space Agency has a launcher called Vega Launcher. This was a launch vehicle. So, when this was launched way back before few years in 2013, it has left a huge space debris. It is called Vespa, upper part of a rocket. You could see here the upper part of a rocket. Yes, it is lost somewhere. Right now, the European Space Agency, it is going to send a spacecraft, an interesting mission. The spacecraft, it is going to search for the Vespa because no one knows where the Vespa is present. Good. Based on the pictures, based on the simulation, the spacecraft is going to use artificial intelligence. It is going to search for Vespa. The location of Vespa is unknown. It is going to scan the entire space debris. It is going to search for Vespa, approach towards Vespa. It is going to capture Vespa with robotic arms. What it is going to do after the Vespa is captured? Simple. It is going to push it inside the atmosphere. What will happen when you push something into the atmosphere? It faces friction. It starts disintegrating. So, this is a technology to find out a space debris and disintegrate a space debris. This is going to be launched in two or three years. They are developing it. Clear. Can we go to the next one? Is LSRD launched? Yes. LSRD is launched. Shantanu sir. LSRD is launched. This is operational right now wherein this is yet to be launched. Clear space is yet to be launched. Right now they are working on the algorithms on how to search the space debris and how to capture Vespa. This is yet to be launched and NIO is also launched. NIO is by Chinese National Space Agency. Interesting mechanism. CNSA, Chinese National Space Agency. What is special about NIO? So, it is for mining space debris. It will search space debris. How it is mining? So, it is going to use something like a net. A huge fishing net. This will scoop a large amount of space debris and it will return back to earth. This is the idea. NIO is going to use a fish net. Something similar. It is going to scoop space debris. You can write down. In simple terms, it is going to scoop using net. All the collected debris, it will be burned using electric propulsion system or electronic propulsion system. Capture and burn. That is the idea. Sweep this space debris and burn it. This is just opposite to astroscale. This is also a proposed mission. Astroscale is a Canadian based one. Astroscale, it will use magnets and then it will capture space debris. This is a proposed mission. This is different. Where astroscale tries to use magnet, this is going to use a net and just capture all the space debris. It is going to burn it. Now, the biggest question is, is it going to be brought back to earth? No idea. If at all you find anything in newspaper, please update. But since this is launched by the Chinese National Space Agency, I thoroughly checked the CNSA webpage or the Wikipedia page everywhere. It is not present anywhere. The detail is not given. They have just given one single press release. So, all that we know right now is it can scoop space debris and this is the only picture available. So, after all the debris is scooped inside a net, it will be burnt using the propulsion system. Whether it is going to bring it back to earth for reusing or anything, it is unknown. So, if at all there is update, please follow up. Clear? Next. Skylark system. Skylark, basically traffic cops in the low earth orbit. This is going to be launched by a Canada based company. This is not launched by any of the you know space agencies. This is by a private company. Okay, let me ask you a few, answer a few questions here. Why Vespa in particular? Nisha has a question. So, because ma'am, the mission is by European Space Agency. They created the debris. So, they want to clear up their debris. They want to experiment with the debris that was created by them. That is the reason they chose the Vespa. Vespa was part of Vega Launcher. Vega Launcher belongs to European Space Agency. Clear? They are going to clear this. Next. Question from Abinaya. NEO, is it launched or it to be launched? NEO is launched. NEO is active right now. This was launched before two months. Clear? And next, Ramakrishnan. Karthik Ramakrishnan has a question. Sir, NEO might have environment, particularly ozone layer repercussions. Most likely, yes, if it is going to burn it, if at all if it is going to bring it back, okay, it is fine. But if it is going to burn it somewhere around 400 or 500 kilometers above the surface of earth, then it may have repercussions. Because mostly it is filled with hazardous substances. All the rocket parts, other than aluminum and titanium, there are many other hazardous substances. If it is going to be burnt, yes, it may affect ozone. Clear? Okay. So, Skylar system, it will have series of satellites that will monitor space debris and give information to the ground station. That is all. It is a space situational awareness, SSA, comparable to Project Nedra. The first ever dedicated satellite system for space debris monitoring. Repeat the first ever dedicated satellite system for space debris monitoring. It will have around 12 plus satellites. They have discovered a new term for it, space traffic management. Done? Okay, next. Let us discuss about space stations. Because when we had the GS class, there was only one active space station, the International Space Station wherein right now there are two active space stations, the Tiangong by China and the International Space Station. Good? First, let us discuss about the former space stations, Salu. Do you recollect the name Salu? Salu series, Salu 1, 2, Salu 7. The list of space stations that were operated by USSR. Keep in mind, Salu series. And in fact, we discussed about Salu 7, the space station to which Mr. Rakesh Sharma travelled. The only Indian who has travelled to space. Then, Mir. This was a space station by USSR. Again, Mir and Salu 1, 2, Salu 7. Salu 1, 2, 3, 4, 5, 6, 7. Next, there was a space station called Skylab by USA. Skylab by USA. Then we have a space station called Tiangong by China. Tiangong 1, Tiangong 2. Two space stations by China. All these are de-orbited. Keep in mind, none of them are active right now. All of them are de-orbited. Now, the list of operational space stations right now, the International Space Station and Tiangong. First, let us discuss about International Space Station. I think we have discussed this particular thing thoroughly, but let me repeat it. First, it is not owned by USA. It is governed by International Agreements. It is owned by USA. The participant countries are USA. Then we have Russia, the European Space Agency, Canada and Japanese Aerospace Exploration Agency. The largest artificial satellites that is active right now. The largest artificial satellite that is active right now. Keep in mind, the Tiangong Space Station, even when it is completely done, it is not going to be as big as International Space Station because right now it is around the 400,000 tons, the International Space Station. I am giving you a rough value. It is more than this, around 400,000 tons because this was not built in a single stretch. Keep in mind, only when they built a space station, first they will send a module and then the modules, rest of the modules, they will travel afterwards and they will be docked together. So, what you see right now as International Space Station? It was not transported as such. Only the modules were transported with slowly they were docked together and then they built a big one like a legal block. Now, with respect to International Space Station, first, it travels at the rate of 27,600 kilometer per hour. So, the main reason for putting this data here is this is located in low earth orbit. So, to defy the gravity without being pulled inside the earth, it has to travel much faster and it covers at least 15.5 orbit setting crosses or it orbits the earth at least 15.5 times a day. Okay, all these data are apart. First, let us start with the recent updates about International Space Station. First, you have to learn about something called as Progress MS-16. So, what is this Progress MS-16? Keep in mind, the International Space Station, it is constantly occupied since 2000. For more than two decades, there is someone always present in International Space Station, even right now, there are around three astronauts who are present in International Space Station. Good. So, this Progress MS-61, this is an unmanned launch vehicle by Russia and this transported food, fuel and water to International Space Station. Keep in mind, it is not always manned mission, sometime they just send the car go alone. This was a recent update, a spacecraft by Russia that sent food, fuel and water to International Space Station. Next, Russia, it has replaced a part of the entire International Space Station. There is a small part called PIRS, P-I-R-S. PIRS was one of the module, an older module. So, this has been replaced with a module called NAUKA, N-A-U-K. So, this is important because this is the largest space module sent by Russia till date. This will serve as a laboratory with some additional bits, gives more space to Russia. Russia recently opted out, Shantanu was asking, didn't Russia recently opt out? So, Shantanu, Russia has particularly said like China and India, it is going to build its own space station, but it will be part of the International Space Station at least till 2024. For another three years, Russia will still be part of International Space Station, clear? Yeah. So, this research facility, this is the largest research facility that is built by Russia on the International Space Station and also keep in mind, the PIRS it is going to disintegrate. The previous one, the Progress MS-16, it is going to dock with PIRS and it will enter into the atmosphere. Effectively, the Progress and PIRS, both of them they will disintegrate into the atmosphere. If at all there is any remaining debris, it will fall into the ocean, clear? We go to the next one? Next. Commercial Crew Program, CCP. There is a stiff competition between two people who is going to send astronauts to the International Space Station. NASA, they don't have their own launch vehicle. The main reason is, once the space station is completed, they have retired the space shuttle there 2011. So, since 2011, they were using the Russian launch vehicles. Astronauts, they have to travel to Russia and from there, they will be launched to International Space Station. That is how it generally works. And right now, USA wants to have their own launch vehicle for that purpose. Similar to India, even USA space program is highly privatized. Right now, there is stiff competition between two people. One is Boeing, the other one is SpaceX. Out of which right now, the most successful one is SpaceX. Keep in mind, both of them, they are developing crew modules so that they can send astronauts to space. Right now, the SpaceX one, there are two successful missions. Crew one and crew two. Crew one is completed, crew two is still active. If you see the line crew, it's related to SpaceX sending people to the International Space Station. So, this was launched in the year 2020 and it was completed in the year 2021. Crew one, it's over. Around three or four people travel and the mission is over. Crew two, they are active right now. And if you have ever heard that Sunita Williams is selected as part of, she's going to travel to International Space Station. Keep in mind, she's part of the Boeing mission, not the SpaceX mission. Sunita Williams is part of Boeing Starliner mission, not the Crew Dragon mission. Crew Dragon, that's a keyword related to SpaceX mission, Crew Dragon. That's a reentry capsule designed by the SpaceX. This has been successfully tested. This lands in Atlantic Ocean. The first successful landing is completed in the year 2021. In the second mission, it's launched in April 2021. Right now, it's present in International Space Station. Where in Boeing, even before two days, there was update. CST 100 Starliner. This was supposed to be tested but because of some technical issues, it's delayed. So, it may take more time for Boeing to come into the play. Good. We go to the next one. The Tiangong Space Station. Why this is special? First, China sent a core module. This is like stem of the space station, the center part of the space station. The core module was sent and after that, three astronauts are sent to Tiangong Space Station. China's first independent spacewalk. They were sent through a vessel called Shenchao 2, Shenchao 12, also called as Divine Vessel. You won't get a question like this, but if at all, you see these terms in the choices, Divine Vessel or Shenchao 12, it's related to the Tiangong Space Station. This is the launch vehicle that sent three astronauts to the Tiangong Space Station. The first spacewalk is completed. Keep in mind other than International Space Station. In recent times, China has made successful spacewalk. Shweta is asking, what is PIRS? Ma'am, NAUKA is the new module. So, NAUKA is basically a space. Imagine you build a room where you can carry out research activities, where you have extra beds, latrines and everything. The entire room is called as module. So, similarly, NAUKA is a module. The previous module was PIRS. PIRS was just a space. So, if you see the International Space Station, each space agency, they have their own modules where their astronauts can stay. There will be laboratories to perform microgravity experiments and also there will be bathrooms and everything. So, similarly, PIRS was a older module which is detached and NAUKA is docked. This is active, clear? Can you repeat a point on crew 1 and 2, someone from RER? So, crew 1, after a few tests, it successfully launched astronauts in the year 2020. They stayed in International Space Station for few months and they returned to the year 2021. So, the first commercial crew program was Crew Dragon 1 by SpaceX. Right now, the second commercial program Crew Dragon 2 is active, which means the astronauts are successfully launched. They are docked. They remain docked to the International Space Station right now. They are performing experiments and after a few months, they will be returning back. Crew 1 and Crew 2, is it clear? Skylar point you missed out. Crew Dragon is keyword for SpaceX, yes, yes. The Crew Dragon is the reentry module that is designed by SpaceX, generally launched using Falcon rocket wherein CST Starliner, Starliner, it is designed by Boeing and it will be launched using Atlas rocket. So, you do not need this much technical detail, but generally remember Crew Dragon, SpaceX, International Space Station, Starliner, Boeing, International Space Station, that is all. These are the keywords required. Clear? We will go to the next one. For the Skylar system, 1 plus naught, SAR or madam. The Skylar system, it is a system developed by private company. They are going to send the 12 satellites that will form spirals. So, these spirals, they will monitor the space and if there is a space debris approaching, they will give information to you that a space debris is approaching your satellite, for which they will be getting money. So, this is like a new business model. Since space debris is a growing problem at Canada based company, it is building its own constellation of satellites so that they can give information about space debris. This is the idea. Basically, it is traffic cop in the space. Clear? Boeing is by whom? Boeing is by the company, Boeing. Lockheed Martin, Boeing, all these are private companies in USA. Clear? Next. About Transporter 1 or Ride Share program by SpaceX. Transporter 1. So, what is special about Transporter 1? This particular launch vehicle, it broke the record of India. So, it launched 134 satellites in a single launch by SpaceX. Till January 2021, India held record for launching highest number of satellites in a single launch that was PSLV C37. PSLV C37, it launched around 104 satellites. This is the highest by an Indian launch vehicle. In a single launch, we launched 103 satellites in multiple orbits. This was the record which was broken in the year 2021 by a program called Transporter 1, also called as Ride Share Program. You are asking about Virgin Galactic Space Technology and Blue Origin. So, all these are for space tourism. We are not talking about it right now. Maybe in next class, I will give you a small introduction. Next. Let us talk about something called as South Atlantic Anomaly. Important. Very important. South Atlantic Anomaly. What is this South Atlantic Anomaly? The earth acts like a giant magnet. To take earth, it will have a magnetic north and magnetic south. We have magnetic lines of force acting in this direction. What is the use of these magnetic lines of force? We are protected from the solar wind. Basically, the entire solar wind it is shielded. Earth is protecting us from the solar wind. And if at all it enters through the north poles and south poles, if it interacts with the magnetic fields, we have auroras, the northern lights and southern lights, aurora borealisis and the aurora australis. Yes. Right now, there is a dent in this magnetic shielding to the south of Atlantic Ocean. That is what we call as South Atlantic Anomaly. You could see here, there is a dip in magnetic field. So, what it means? What is the problem that may be caused because of this? Imagine it looks something like this. If you draw the magnetic protection, it goes like this and then there is a dip and again it starts. So, because of that, the coronal mass ejections, the solar particles, it can enter into this particular region. Which means, first thing, the earth not only protects us, it also protects the satellites present in lower orbit. So, which means, satellites travelling in this particular region, they may face the risk of damage. And in recent times, this South Atlantic Anomaly, it is splitting into two lobes. First point, South Atlantic Anomaly, it is a dip in Earth's magnetic field. First point, more details are given in the material, you can read later. There is a dip in Earth's magnetic field. First point, second, who are going to be affected? More than humans, it is less likely to cause any impact on humans, but mostly satellites will be affected. The electronics on the satellites will be affected, keep in mind. And in recent times, it has started to split, it has formed two lobes. Now, the reason, there are multiple theories, right now there is one theory. First, you can write down. So, the tilt of the Earth's magnetic axis, first, the Earth's magnetic axis is tilted, correct? The normal axis is different from magnetic axis. The tilt of Earth's magnetic axis, first one. And second one, flow of molten material from interior of Earth. Molten material from interior, and also, tilted Earth's magnetic axis. These two are said to be the reason for dip in South Atlantic region. Yes, Earth's magnetic field is weak, clear? Okay, next. Camargon meteorite. So, Camargon is a place in Assam where a meteorite fell before few years. What is special about this Camargon meteorite? You could see a small piece of meteorite. First, the difference between meteoroid, meteorite and everything. A quick revision, meteorite, basically rocks that are floating around the solar system, which may enter into atmosphere of a planet or a moon or any object. Meteoroid, it is divided into two types. We have meteor, and then we have meteorite. So, what is the difference between meteor and meteorite? So, the meteorite enters into atmosphere of a planet, and before it reaches the surface, it will completely disintegrate. It will turn into ashes. There is no impact. When meteorite, it burns because of atmospheric friction, but still it manages to reach the surface of a planet. That is called as meteorite. We had a meteorite in Assam that fell on a region called Camargon. So, this happened way back in 2015, but there is a recent study about it. So, what is the recent study? The study about this particular meteorite, it can help, it may help us to understand about interior of the earth. Repeat, the study about this meteorite, it may help us to study about interior of earth. How? How a meteorite can help us to study about interior of the earth? So, because the parent material that makes the meteorite, that matters. It is made up of a material called olivine. The meteorite, it is made of olivine. It is earth forming material. So, this same olivine, it is found in upper mantle of the earth. This is created generally because of high pressure and temperature, upper mantle. I repeat, it is an upper mantle not a lower mantle. Olivine is created in upper mantle of the earth. And slowly over time, it will break down. In upper mantle, we have olivine. This olivine will generally break into two materials. These two materials are important. First, brygmanite and the second one. It is difficult to spell it, but still. Magnesium, you cite. This olivine, it will break into brygmanite. I will write an individual letter so that it will be easy for you. B, R, I, D, G, M, A, N, I, T, brygmanite and magnesium, you cite. You cite. Shakti, can you explain second one? Which one you are asking? Can you repeat once again? Okay. So, this is the process that happens in the upper mantle layer. In upper mantle layer, olivine will break into brygmanite and magnesium, you cite. But if you read about olivine that controls the interior of the earth, we may be able to understand about interior of the earth. So, this is the same olivine it is present in Camargon meteorite which is a recent discovery. That is all. This is the news. Camargon meteorite, it has olivine. Keep this in mind. Clear? Can we go to the next one? Next one is extremely important. Tassifae. Polar areas still are imaging in polarization high accuracy experiment. Tassifae. Why is this important? So, this is a sky surveying project. Sky surveying project. We are going to count the stars. India is part of it. Sky surveying project. Can you recollect the term polarization? When we were discussing about lumen 16a, I said something called as polarization. For example, if you take a transverse wave, it has two components. Generally, it will oscillate in multiple directions. So, similarly, the earth, the light also, it is omnidirectional. It will have different phases. We are going to put it through a polarization filter. What will happen? Only one phase will be filtered, correct? Only one phase will be filtered. That is called as polarization. Something like this. Can you recollect the picture which I showed in the GS class? The directional orientation of light. You call it as polarization. So, similarly, we are going to build a polarimeter. So, what is special about the polarimeter that India is building? First, you could see four arms, correct? You could see four arms. It is going to simultaneously observe in both directions, in north side and south side. It is going to observe the sky in northern direction and southern direction. And this particular polarimeter as assembly is built by India. Keep in mind, this instrument is not going to be located in India. Only the particular assembly is built in India. It is going to observe all the fine stars. Going to observe southern and northern skies simultaneously. This particular passive way instrument, okay? There are three components. I will repeat. First, the passive way instrument. It is going to observe the stars. And the distance of the star, it is going to be calculated by GAIA. Please note this down. This is important, GAIA. This is observatory by European Space Agency. Astrometry spacecraft by European Space Agency, GAIA. Passive way slide, okay, hold on. Polar, it is still imaging in polarization and higher physics experiment. This is just the expansion for passive way. You can easily find it. I have even given the official website material. You can read more if you want. First, India is designing the polarimeter. The polarimeter, it is going to observe northern sky and southern sky simultaneously. And when it observes a star, the location of the star is given by GAIA. Okay, perfect. Now, where this is going to be located? This polarimeter is going to be located in a particular telescope. It is called VALOP, W-A-L-O-P. VALOP, there will be two telescopes. On both the telescopes, they will be launching the particular polarimeter. That is the idea. Yeah, you first write it. I will give you a clear cut idea once again. I am done. Okay. Once again, I will give you a clear explanation. See here. First, passive way is basically a polarimeter. A polarimeter that will have four arms. It will be tracking both the northern sky and southern sky. This is the idea. Okay. So, this passive way will be mounted on VALOP, which is a telescope. It is located in two different regions. Okay. The passive way, it is going to be mounted on VALOP. So, this VALOP it will observe the star. This will observe star. Okay. This observation will be aided from the sky by GIA. This is the European Space Agency. This will provide the location. This will measure the location of star, wherein this will measure the polarimeter of the star, which is a polarized light from the star. And both of this, it will be used to create an image. We call it as a magnetic field tomography mapping. It would need two technical, but still magnetic field tomography mapping. A map will be created. That is all. This itself is two technicals. Since India is involved in the particular initiative, I have to explain this much, but this is sufficient. Passive way, this component is built by India. Keep that in mind. Clear? Next. A mechanism that was mentioned in the news, induced torpor or how we are going to reach Mars. The first problem for all our interplanetary missions, the earth is perfectly shielded from radiation by atmosphere. But if you are going to Mars, the Mars has a much thicker, sorry, the Mars has a much thinner atmosphere. How we are going to protect ourselves from ionizing radiation? That is one biggest issue. Ionizing radiation, including the cosmic ray background. The cosmic ray background and all the ionizing radiation that passes from the universe, how we are going to be protected. And first of all, while traveling, the astronauts will face muscular loss. They will face distress and everything for that. We have a new mechanism which is under study. That is called induced torpor. It is a form of hibernation followed by the fish. This fish is called zebrafish. This is native of South Asia. So, this zebrafish, what is hibernation? Whenever there is a harsh climatic conditions, the animals will go on a reduced metabolic state. You call it as hibernation. We have hibernation, astabiation, winter sleep and summer sleep. So, this zebrafish, it follows a hibernation called the mechanism is called induced torpor. The mechanism is called torpor. We are going to induce torpor. So, how this was tested? This is based on a topic from down to earth. First, they took first set of fish. A Martian environment or environment similar to space travel, it was simulated for the fish wherein all of them faced distress. They were highly disturbed. Now, set number 2, fish set number 2, they were induced into torpor. They were induced into the hibernation mechanism. So, when they were in hibernation state, they were given radiation dosages. Simulation of space travel was created wherein none of them were disturbed, which means if it is in hibernated state, it is not getting disturbed by radiation, it is not getting disturbed by space travel. So, what if we are able to replicate and simulate the same thing on the human? This is a thing under study, that is all. It is possible that we may still go under hibernation. So, that all the way through the travel to the Mars, we can still sleep without requiring much of food or without requiring much of energy and we we will not feel disturbed. This is the idea. It is still under research. Just remember induced torpor, this line alone. Clear? Next. Can you recollect the life cycle of star that we have discussed? Yes, two types of stars, massive stars and the low mass stars. For a quick revision, let us take low mass star. Low mass star, it will start using hydrogen to helium and everything. It will form protostar, it will form main sequence star. The main sequence star, it forms red giant and from red giant it undergoes something called as planet tree nebula and then it forms a white dwarf. What forms after white dwarf? It is a black dwarf. So, this is for low mass star, a star with a lower mass. Where in for a star with higher mass, it is totally different. It has a after the red giant phase, it has something called as a supernova detonation. When supernova detonation happens, it can either form a neutron star or it can form a black hole. When it forms a neutron star and when it forms a black hole for a quick revision. First, if the remnant mass, if it is up to from 1.6 times the solar mass up to 3 times the solar mass, then it will become a neutron star. Along with this picture, I have clearly explained what does mean by life cycle of star in the material. You can download it, you can read it once again. And then if the remnant mass, it is going to be greater than 3 times the solar mass, then it will form black hole, correct? Now, three things. End of stars. We are going to talk about white dwarf. We are going to talk about neutron stars. And we are going to talk about black holes. Three different things, good. So, almost time we will just take one or two topics and then we will wind up. Good. First, supernova SN 2015 DJ. This is particularly important because this type of supernova is predicted or it is calculated by scientists from Aries, Aribata Research Institute of Observational Sciences. In Indian context, this is important. Yes, Isha even remembers the Chandrasekhar limit. Good. 1.6 times the solar mass, it is called as a Chandrasekhar limit. Yeah. 1st. So, the Indian astronomers, they have observed a type of supernova. It is called as supernova SN 2015 DJ. It has been classified as type 1B supernova. Type 1B. Can you recollect the type 1A supernova which we are talking about? This is type 1B supernova. So, what is this type 1B supernova? So, this particular supernova explosion, it is created by a type of star called as Ulf Reitstar. Ulf Reit. I am introducing you to a new type of star, more than the class. Ulf Reitstar. So, they have mass up to from 13 or up to 20 times the solar mass. Their mass is high and most importantly, their temperature is also high, extremely high. So, these Ulf Reit stars, there is something called a stellar wind. When the star is undergoing nuclear fusion, a star wind can cause the outermost part of the star to strip away. I repeat, the outermost part of the star, it may strip away, which means hydrogen it may be stripped off. So, these stars are called as Ulf Reit stars, a rare type of supernova which was observed by Indian astrophysicists. That is all. Good. Stellar wind or a star wind. When stellar wind happens, the topmost layer of the star, it will be stripped off. Generally, the hydrogen will be washed away and after that, if the supernova detonation is going to happen, you call it as type 1B supernova and this happens in Ulf Reit stars, extremely rare type of supernova which has been detected by Indian astrophysicist. That is all. It is also released in PIB. So, for that reason, I put it here. Do not dwell into much of technical detail, just have an idea about it. That is all. Ulf Reit stars. Clear? Next. Unicorn black hole. The smallest ever black hole in Milky Way discovered till date. So, it is just three times the mass of Sun, three times the solar mass. The smallest black hole ever discovered in the Milky Way. This is present in Milky Way and it is not a single system. Again, it is a binary system. It is a black hole binary. It has a black hole and then it has star. Both of them, they are orbiting on a common axis. Altogether, the system is called as V723. The system is called V723. It is present inside the Milky Way. Keep in mind, this is the smallest known black hole in the Milky Way. Not anywhere else, just in Milky Way because we are not talking about the primordial black holes here. We are talking about black holes present inside the Milky Way. Done? Okay. Next, BL Lakrte. Again, Indian context. BL Lakrte. BL Lakrte. What is this? BL Lakrte. Can you recollect three concepts that we were discussing? Active galactic nuclei. AGN, active galactic nuclei. In active galactic nuclei, I gave you three classification. We have radio galaxy. Then we have something called as a quasar and then blazar. Correct? Quasar, blazar. Now, the news is about quasar. A tilted galaxy that has a highly accreting disk. What is active galactic nuclei? A galaxy is called highly active. If the center part of the galaxy, it is going to spew a lot of materials. It is going to have high amount of radiation. You call it as active galaxy. Correct? Now, recently they have discovered active galactic nuclei that is called BL Lakrte. Again, this is reported by Indian astronomers. That is why it is important. BL Lakrte, it is a highly accreting quasar. I repeat, it is a quasar. Next, this BL Lakrte is located around 10 million light years away. I repeat, 10 million light years away from us. Keep in mind, so far only 50 quasars can be observed properly. Out of these 50 quasars that can be observed with a small telescope, BL Lakrte is the most prominent one, an important discovery made by Indian Institute of Astrophysics. Again, this is also by Arivatar Research Institute of Astronomical Sciences, Observatory Sciences. This is also from Aries. Clear? Again, you do not have to dwell much deeper into it. Even mainstream newspapers, they did not cover it properly. This is only found in the Department of Science and Technology page. In the material, I have given you the link. If it is all required, you can go through it once. Clear? And then P172 plus 18. We have two more topics left over. We will just finish it. P172 plus 18. So, this is the most distant quasar ever discovered. Most distant. So, how do you say, how do we say that this is the most distant quasar? Have you heard about something called as Redshift and Blueshift? Two terms, two important terms, Redshift and Blueshift. Out of the entire WebJR color, can someone tell me which one has the highest wavelength? Which one has the highest wavelength? Come on quick. Doppler effect. Yes, good. Red has the highest wavelength. Exactly. So, imagine you are observing from Earth here. Good. If something is approaching closer to you, you will have blue wavelength. The particular object will exhibit the blue wavelength. We call it as Blueshift. If the particular object is moving away from the Earth, in that case, the space will be stretching and the light will also stretch. It will have red color radiation. We call it as Redshift. Something like this. Closer to Earth, we have Blueshift. When it is moving away from Earth, we have Redshift. So, based on the Redshift, based on the Doppler effect, we have deduced this is the farthest quasar that we have discovered so far. The most distant quasar that we have discovered so far and interestingly, can you recollect the big billion period, 13.7 billion years. The big bang happened before the present date happened 13.7 billion years before the present day. Wherein the signal from this particular quasar, it was created 30 billion years away before 13 billion years. It took 13 billion years for the quasar to reach us, which means this is almost somewhere towards the end of the universe. It took 13 billion years for the signal to reach here. It is called as Radio Loud Quasar. Good. So, this is by international group of astronomers, not just single person. Okay, the last topic. Let us talk about IEEE milestone. One specialty in India, it has been accredit as IEEE milestone, the Jainte Meter Radio Telescope. In fact, it has been upgraded right now. It is called as UGMRT. It is located in Pune. Upgraded Jainte Meter Radio Telescope. Upgraded Jainte Meter Wave Radio Telescope. So, this is operated by the Tata Institute of Fundamental Research. And recently, it has been upgraded IEEE milestone. Have you heard of IEEE milestone? IEEE. The people who are from engineering background, you would have heard about it, because whenever you prepare the projects, you will search for IEEE papers. Most of the academic institutes, they will have the subscriptions to the IEEE, correct? Yes, the Institute of Electrical and Electronics Engineers. Institute of Electrical and Electronics Engineers. So, recently, this particular organization, it has accredited IEEE milestone to UGMRT. So, what is special about this? So, this is only the third incident or facility to get IEEE accreditation in India. Repeat in India, not worldwide in India. So, what are the other two accreditations or other two milestones? The first one, it was to appreciate or it was to honor the works of Mr. Jagdish Chandra Bose from India. For his work in radio physics, first IEEE milestone, it was given to Mr. Jagdish Chandra Bose for his work in radio waves. In fact, his works were in 1895. Keep in mind, the accreditation was given much later in the year 2012. A recent accreditation, a recent IEEE milestone, JC Bose. Next, who discovered the scattering of light phenomena from India? Mr. Sir C. V. Raman, correct. The second IEEE milestone given to India was for Raman scattering for the discovery made by Sir C. V. Raman. This is considered to be a pride when some facility or when a person gets IEEE milestone. This considered to be a pride and the third ever IEEE milestone, it is given to graded giant meter wave radio telescope. So, keep in mind, Japan has the highest number of milestones right now. They have around 37 milestones, 37 presently active IEEE milestones. This in Japan, not even USA. This may sound like a normal news, but keep in mind the S. Rose Charmin, including our prime minister, Mr. Narendra Modi, everyone appreciated GMRT for its effort because this has been up, this is a radio telescope, it has been observing especially the low frequency. Keep in mind low frequency radio waves. This radio telescope which is operating in Pune, it has been observing low frequency radio waves for a longer time. It has made significant contribution to the scientific community both in India as well as globally. For that reason, it has been given the IEEE milestone, clear? Okay. We are almost towards the end of the session. Yeah. Next class, you will have one more session. So, a mini session, maybe around one and half hours maybe. I will be discussing the current affairs related to nuclear technology and biotechnology. Biotechnology is much important for this year, especially because of the COVID pandemic. So, make sure you attend the next session. Good. Yeah. Very people comfortable with the session. Is everything fine? Mohan? Good. People here? Yeah. All fine? Good. Yeah. The PDF, see two modes by which you can get your PDF. First thing, it will be sent through the Telegram channel today or otherwise. The YouTube, it will have the link either in the description or in the comment, we will be posting the document. So, you can download it. Good. At most effort is taken so that every data is correct. Good. Try to upgrade the notes and I have not encrypted or did anything so that you can just update, you know, just highlight and do everything. You can print the document if required or you can keep on highlighting. Good. It is a companion. It is a collection. It runs around 150 plus pages. You do not have to read everything and certain places I would have put food notes, something like it is only for mains perspective. Do not memorize. I would have given notes. So, make sure you read the document well. Clear? GMRT Expansion, CWPMM. UGMRT, it is Upgraded Jaint Meter Wave Radio Telescope. Waiting for your class and notes for a long time. We understand that people are waiting for the notes for a longer time. Sorry about it. We wanted to upgrade along with the current affairs. Right now it is ready. Yeah. All right. So, can we wind up the session? Is there anything posted in Q&A? Please reply for mail, sir. Yeah, sure. So, Japan having how much milestones as right now they have around 37 milestones, the highest by any single country. Is this a UGMRT is the thing that we discussed about size of telescopes? No, no, no. In class we were discussing about Indian Astronomical Observatory that has this growth telescope, Haager High Energy Gamma Ray Telescope and then May's Major Atmospheric Cherenkov experiment. And then we have one more telescope that is called Himalayan Sandra Telescope. That is totally different. That is located in you know the Himalayan region, Hanley in Ladakh wherein this is located in Pune. This is operating in rural parts of Pune. This is different one. Clear? Okay. Okay. Are there any other doubts to be cleared? Let me go through this video of introduction of biology. Ponte sir, are you from batch 9 or 10? Because I think for one batch it is missing. Mr. Ponte are you from batch 8, 9 or which one? Batch 10. Okay. So, I will tell them to fix it because we had few issues related to the browser, correct? So, for batch 10 I told you to watch the introductory video to biotechnology. I will ask them to send it today. Sure. P172 plus 18 is a redshift or blueshift. Sivapriya ma'am, this has traveled around 13 billion years, which means it is much far away, definitely redshift. P172 plus 18, the radio loud galaxy, it is exhibiting redshift. Yes. Yes, Ankitam ma'am, this is the same thing that Pandey's are told. I will fix the issue. I will ask them to send the, you know, introductory video to biology in a span of two or three days maximum. I thought they have posted it. So, now only you got to know that it is not posted. Sorry for the inconvenience. We will fix it. Good. Shakti sir, for the South Atlantic anomaly, it is because of two things. First thing, the general tilt of earth is different from the magnetic tilt. For example, we have a equator and then then we have a magnetic equator. So, the magnetic field of the earth is tilted. That is reason number one. And reason number two is it may be because of material flowing from the core layer to the mantle layer. So, these are the two possible explanations. These are theories. These are not yet confirmed. All that we know is there is a depends out Atlantic region. Clear. We have to get more, we have to get notes about nanotechs. So, for nanotech generally you have to follow any updates about nano electronics, nano biology because nanotechnology we cannot compress into a single topic spread throughout. Even in electronics we have nanotech, even in biology we have nanotech. So, basically nanos 10 power minus 9. Any technology that uses a minute elements you call it as a nanotech. So, it is present everywhere. If you just see the current efficient update, it will be fine. Done. Narendra sir, can you drop a mail about the black hole thing because will there be notes on biotech also? Yes, yes, I will be sending notes for biotech also. For now, I have sent updated notes for space science and astrophysics. wherein you will be getting updated notes for nuclear science and biotech in the next session. Most it will be by Wednesday or Thursday in the coming week and then you will be getting the rest of the notes, clear? Sure. Right sir. So, I think I have answered most of the questions right till I see you people in the next session. Stay home, stay safe, take care of yourself, prepare well, good. I will see you in the next session. Thank you very much. Bye bye.