1 Summary Science and Technology Class 03 ## Discussion on the Previous Class (5:06 PM) ## Satellite Navigation (5:18 PM) - These satellites allow a small electronic receiver to know its precise location (i.e. latitude, longitude, and altitude) with high accuracy. - The point needs to be in the line of sight of at least four satellites to know its precise locations. - GPS - USA - GLONASS - Russia - Galileo - Europe - Beidou - China - NAVIC - India - ==NAVIC== - ==== - It stands for Navigation of Indian Constellation. - It is a navigational satellite system, developed by ISRO. - It comprises seven IRNSS (Indian Regional Navigational Satellite System) satellites. - Three satellites in geostationary and four in geosynchronous. - Similar to other navigational satellite systems, it provides two types of services, standard services for civilian use and restricted services for military use. - | | | | --- | --- | | **NAVIC** | **GPS** | | It is regional. NAVIC services are available in India and 1500 km beyond India's border. | It is a global satellite system. | | There are 7 satellites | There are 32-33 satellites. | | Satellites are placed in geostationary and geosynchronous orbits. | Satellites are placed in medium earth orbit. | | Very low cost compared to GPS. | Higher cost. | - ==These satellites have applications in many areas, such as:== - (a) Areal, terrestrial and marine navigation. - (b) vehicle tracking - (c) Integration with mobile phones. - (d) Precise timing - (e) Disaster Management - **GAGAN** - It stands for GPS-aided Geo Augmented Navigation. - It is used for civilian aeroplanes mainly - This was developed by the Airport Authority of India and ISRO, jointly. - It can be used to tell the precise location of aeroplanes at any time. ## Launch vehicles of ISRO (6:35 PM) - The purpose of the launch vehicle is to send a manned or unmanned mission, to space. - It can have the following major components: - (a) Payload box - (b) Engine - There can be two types, Airbreathing, and non-air breathing - Non-air breathing engines carry fuel and oxygen together, For example, PSLV, GSLV, etc. - Air-breathing engines fulfil their oxygen requirement from the atmosphere. For example, Jet, Ramjet, and Scramjet. - ISRO has developed the VIKAS engine, which operates using liquid fuel. - ==Rocket fuel (Propellant)== - It can be of two types, Solid fuel, and liquid fuels. - ==Solid Fuels== - Solid fuels are simpler, safer, and cheaper. - However, once they start burning the resulting thrust cannot be controlled. - For example, HTPB (Hydroxy Terminated Poly Butadiene) - ==Liquid Fuels== - The flow of liquid fuel to the engine can be regulated. Hence, the resulting thrust can also be regulated. - However, liquid fuels require special transportation and storage infrastructure, because of safety issues. It makes them expensive. - For example, UDMH (Unsymmetrical Dimethylhydrazine)+N2O4, MMH (Mono methylhydrazine)+MON(Mix of nitrogen oxides) - **==Launch vehicles of ISRO==** - ==(a) Past== - (i) Satellite Launch vehicle - (ii) Augmented satellite Launch vehicle - (b) ==Present== - (i) Polar satellite Launch vehicle - (ii) Geosynchronous satellite Launch vehicle Mk 3 - (iii) Launch Vehicle Mark 3 - (iv) Small Satellite Launch Vehicle - (c) ==Future== - (i) Next-Generation Launch Vehicle - (ii) SCRAMJET ## PSLV (7:19 PM) - It is one of the world's oldest and most reliable launch vehicles. - It has four stages which operate between solid and liquid fuels (solid, liquid, solid, liquid) - Capacity is about 1750 kg in 600 km polar orbit, and 1425 kg in geosynchronous transfer orbit. - It is capable of placing multiple satellites into different orbits. - Some of the key launches such as IRNSS, Chandrayaan 1, etc took place with the help of PSLV. ## GSLV Mk II - It was designed to launch the communication satellite in geosynchronous transfer orbits. - It has three stages, solid, liquid, and cryogenic - The capacity is 2500 kg in GTO and 5000 kg in the LEO. ## LVM 3(GSLV MK III) - As of now, It is the most powerful rocket of ISRO with a capacity of 8000kg in the LEO and 4000 kg in GTO - It has three stages, solid, liquid, cryogenic - Recently, it made the record of launching 36 satellites of about 6000 kg, in LEO. - These satellites belonged to one web. - In the past, it has also been launched for the Chandrayaan 2. ## Cryogenic stage (7:35 PM) - "Cryo" signifies very low temperatures. - In the cryogenic stage, fuel or oxidizer or both can be stored at very low temperatures in the liquid stage. - For example, liquid hydrogen and liquid oxygen. - Such engines pose engineering challenges, because of associated thermal and structural problems. - However, they provide more thrust than typical solid or liquid fuel. ## Small satellite Launch vehicle (7:40 PM) - It is a small rocket with less capacity (500 kg in LEO), and it can be deployed in less time and cost less. - It has three stages. All the stages use solid fuel. - The first SSLV launch failed. It was not able to achieve the desired orbit. - Recently the second launch occurred which was successful. ## Next Generation Launch vehicle (7:52 PM) - ISRO is planning to design a rocket, to launch a payload of 10000 kg in a geosynchronous transfer orbit and 20000 kg in LEO. - This rocket will have a variant that will be reusable. - Reusable rockets reduce the overall cost, as many components of the rocket are made of rare components which are in limited supply. - The reusable variant will have less capacity, compared to the variant which can be used only once. ## The Topic for the next class: Achievements of the ISRO, Future missions of ISRO