Science of Rocket | Science & Technology for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
Science of Rocket  
•Satellites are launched into orbit by multi-staged satellite launch vehicles that can be used only once 
(expendable) 
•
They carry oxidiser along with the fuel for combustion to produce thrust. Launch vehicles designed for 
one time use are expensive and their ef?ciency is low because they can carry only 2-4% of their lift-off 
mass to orbit 
?Nearly 70% of the propellant (fuel-oxidiser combination) carried by today’s launch vehicles consists 
of oxidiser. Thus, a launch vehicle must use a propulsion system which can utilise the atmospheric 
oxygen during their ?ight  
?Also if these vehicles are made re-usable, the cost of launching satellites will further come down 
•
Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which 
are being developed by various space agencies 
•
Vikas (VIKram Ambalal Sarabhai) Engine 
?It is a family of liquid fuelled rocket engines conceptualised and designed by Liquid Propulsion 
Systems Centre  
? Design was based on the Viking engine of France  
?It powers all the three satellite launch vehicles of ISRO  
? PSLV, GSLV & GSLV Mk-III 
?The main bene?ciary of the high-thrust Vikas engine is said to be the heavy-lifting GSLV-Mark III 
launcher, which ISRO expects will now put 4,000-kg satellites to space 
?The engine is the workhorse liquid rocket engine powering the second stage of PSLV, 2nd stage and 
the four strap-on stages of GSLV and twin engine core liquid stage of GSLV Mk-III 
?The engine is a liquid-fuel engine which uses N2O4 (Nitrogen T etroxide) propellant  
•
Ramjet 
?It is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming 
air for combustion without a rotating compressor 
?Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites 
as opposed to a normal jet engine, in which the compressor section (the fan blades) compress the air 
?A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed 
where it begins to produce thrust 
? The air ?ow through a ramjet engine is subsonic, or less than the speed of sound 
?
It works most ef?ciently at supersonic speeds around Mach 3 and can operate up to speeds of 
Mach 6 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 2


 
Science of Rocket  
•Satellites are launched into orbit by multi-staged satellite launch vehicles that can be used only once 
(expendable) 
•
They carry oxidiser along with the fuel for combustion to produce thrust. Launch vehicles designed for 
one time use are expensive and their ef?ciency is low because they can carry only 2-4% of their lift-off 
mass to orbit 
?Nearly 70% of the propellant (fuel-oxidiser combination) carried by today’s launch vehicles consists 
of oxidiser. Thus, a launch vehicle must use a propulsion system which can utilise the atmospheric 
oxygen during their ?ight  
?Also if these vehicles are made re-usable, the cost of launching satellites will further come down 
•
Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which 
are being developed by various space agencies 
•
Vikas (VIKram Ambalal Sarabhai) Engine 
?It is a family of liquid fuelled rocket engines conceptualised and designed by Liquid Propulsion 
Systems Centre  
? Design was based on the Viking engine of France  
?It powers all the three satellite launch vehicles of ISRO  
? PSLV, GSLV & GSLV Mk-III 
?The main bene?ciary of the high-thrust Vikas engine is said to be the heavy-lifting GSLV-Mark III 
launcher, which ISRO expects will now put 4,000-kg satellites to space 
?The engine is the workhorse liquid rocket engine powering the second stage of PSLV, 2nd stage and 
the four strap-on stages of GSLV and twin engine core liquid stage of GSLV Mk-III 
?The engine is a liquid-fuel engine which uses N2O4 (Nitrogen T etroxide) propellant  
•
Ramjet 
?It is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming 
air for combustion without a rotating compressor 
?Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites 
as opposed to a normal jet engine, in which the compressor section (the fan blades) compress the air 
?A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed 
where it begins to produce thrust 
? The air ?ow through a ramjet engine is subsonic, or less than the speed of sound 
?
It works most ef?ciently at supersonic speeds around Mach 3 and can operate up to speeds of 
Mach 6 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
However, the ramjet ef?ciency starts to drop when the vehicle reaches hypersonic speeds?  
•
Scramjet (Supersonic-Combustion Ramjet) 
?It is an improvement over the ramjet engine as it ef?ciently operates at hypersonic speeds and 
allows supersonic combustion 
?
These are envisioned to operate at speeds up to at least Mach 15 
?The Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric 
air as the oxidiser 
?With the recent testing of Advanced T echnology Vehicle (ATV), a sounding rocket, India became the 
fourth country to demonstrate the ?ight testing of a scramjet engines  
?The scramjet engine is used only during the atmospheric phase of the rocket’s ?ight  
?Factors like air inlet design, air compressibility, complex ?ows, high temperatures, fuel injection, etc 
– make it really dif?cult to design a suitable scramjet powerplant. Scramjets are highly inef?cient at 
low speeds, with their ef?ciency increasing at supersonic speeds 
?India is the fourth country to demonstrate the ?ight testing of Scramjet Engine after the US, Russia 
and European Space Agency 
?According to ISRO, the development of a Scramjet system is extremely complex as it involves many 
technological challenges, especially relating to mixing of very high speed air (velocity around 1.5 
km/s) with fuel, achieving stable ignition and ?ame holding in addition to ensuring ef?cient 
combustion, within the practical length of the combustor 
?Importance 
?
PSLVs are expendable, meaning that can only be used once, and are designed to carry both fuel 
and oxidizer with for launch. Scramjets use ambient air to burn fuel, thus saving the need to 
carry an oxidizer – thus increasing the payload of a craft 
? Since there are no rotating parts in a scramjet, the chances of failure are also measurably 
reduced 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 3


 
Science of Rocket  
•Satellites are launched into orbit by multi-staged satellite launch vehicles that can be used only once 
(expendable) 
•
They carry oxidiser along with the fuel for combustion to produce thrust. Launch vehicles designed for 
one time use are expensive and their ef?ciency is low because they can carry only 2-4% of their lift-off 
mass to orbit 
?Nearly 70% of the propellant (fuel-oxidiser combination) carried by today’s launch vehicles consists 
of oxidiser. Thus, a launch vehicle must use a propulsion system which can utilise the atmospheric 
oxygen during their ?ight  
?Also if these vehicles are made re-usable, the cost of launching satellites will further come down 
•
Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which 
are being developed by various space agencies 
•
Vikas (VIKram Ambalal Sarabhai) Engine 
?It is a family of liquid fuelled rocket engines conceptualised and designed by Liquid Propulsion 
Systems Centre  
? Design was based on the Viking engine of France  
?It powers all the three satellite launch vehicles of ISRO  
? PSLV, GSLV & GSLV Mk-III 
?The main bene?ciary of the high-thrust Vikas engine is said to be the heavy-lifting GSLV-Mark III 
launcher, which ISRO expects will now put 4,000-kg satellites to space 
?The engine is the workhorse liquid rocket engine powering the second stage of PSLV, 2nd stage and 
the four strap-on stages of GSLV and twin engine core liquid stage of GSLV Mk-III 
?The engine is a liquid-fuel engine which uses N2O4 (Nitrogen T etroxide) propellant  
•
Ramjet 
?It is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming 
air for combustion without a rotating compressor 
?Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites 
as opposed to a normal jet engine, in which the compressor section (the fan blades) compress the air 
?A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed 
where it begins to produce thrust 
? The air ?ow through a ramjet engine is subsonic, or less than the speed of sound 
?
It works most ef?ciently at supersonic speeds around Mach 3 and can operate up to speeds of 
Mach 6 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
However, the ramjet ef?ciency starts to drop when the vehicle reaches hypersonic speeds?  
•
Scramjet (Supersonic-Combustion Ramjet) 
?It is an improvement over the ramjet engine as it ef?ciently operates at hypersonic speeds and 
allows supersonic combustion 
?
These are envisioned to operate at speeds up to at least Mach 15 
?The Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric 
air as the oxidiser 
?With the recent testing of Advanced T echnology Vehicle (ATV), a sounding rocket, India became the 
fourth country to demonstrate the ?ight testing of a scramjet engines  
?The scramjet engine is used only during the atmospheric phase of the rocket’s ?ight  
?Factors like air inlet design, air compressibility, complex ?ows, high temperatures, fuel injection, etc 
– make it really dif?cult to design a suitable scramjet powerplant. Scramjets are highly inef?cient at 
low speeds, with their ef?ciency increasing at supersonic speeds 
?India is the fourth country to demonstrate the ?ight testing of Scramjet Engine after the US, Russia 
and European Space Agency 
?According to ISRO, the development of a Scramjet system is extremely complex as it involves many 
technological challenges, especially relating to mixing of very high speed air (velocity around 1.5 
km/s) with fuel, achieving stable ignition and ?ame holding in addition to ensuring ef?cient 
combustion, within the practical length of the combustor 
?Importance 
?
PSLVs are expendable, meaning that can only be used once, and are designed to carry both fuel 
and oxidizer with for launch. Scramjets use ambient air to burn fuel, thus saving the need to 
carry an oxidizer – thus increasing the payload of a craft 
? Since there are no rotating parts in a scramjet, the chances of failure are also measurably 
reduced 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
ISRO claims that using Avatar for satellite launches will cut down launch costs by half 
? ISRO’s reusable launch vehicle platform, called Avatar, is a concept that is capable of 
carrying out satellite launches – takes off vertically and lands back on a runway 
?
In defence, the next generation of cruise missiles is likely to be powered by scramjets that reach 
hypersonic speeds 
?
Civil aviation could commercialise air-breathing rocket engine technology.   It has a greater 
incentive and a bigger market. Intercontinental ?ights which use scramjets to reach hypersonic 
speeds at the edge of space would cut travel time by a factor in the range of a ?fth to an eighth? ?  
•Dual Mode Ramjet (DMRJ) 
?Type of jet engine where a ramjet transforms into scramjet over Mach 4-8 range, which means it can 
ef?ciently operate both in subsonic and supersonic combustor modes 
•Cryogenic Engine 
?A cryogenic engine/ cryogenic stage is the last stage of space launch vehicles which makes use of 
Cryogenics. Cryogenics is the study of the production and behaviour of materials at extremely low 
temperatures (below -150 degree Centigrade) to lift and place the heavier objects in space 
?Cryogenic rocket stage is more ef?cient and provides more thrust for every kilogram of propellant it 
burns compared to solid and earth-storable liquid propellant rocket stages 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 4


 
Science of Rocket  
•Satellites are launched into orbit by multi-staged satellite launch vehicles that can be used only once 
(expendable) 
•
They carry oxidiser along with the fuel for combustion to produce thrust. Launch vehicles designed for 
one time use are expensive and their ef?ciency is low because they can carry only 2-4% of their lift-off 
mass to orbit 
?Nearly 70% of the propellant (fuel-oxidiser combination) carried by today’s launch vehicles consists 
of oxidiser. Thus, a launch vehicle must use a propulsion system which can utilise the atmospheric 
oxygen during their ?ight  
?Also if these vehicles are made re-usable, the cost of launching satellites will further come down 
•
Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which 
are being developed by various space agencies 
•
Vikas (VIKram Ambalal Sarabhai) Engine 
?It is a family of liquid fuelled rocket engines conceptualised and designed by Liquid Propulsion 
Systems Centre  
? Design was based on the Viking engine of France  
?It powers all the three satellite launch vehicles of ISRO  
? PSLV, GSLV & GSLV Mk-III 
?The main bene?ciary of the high-thrust Vikas engine is said to be the heavy-lifting GSLV-Mark III 
launcher, which ISRO expects will now put 4,000-kg satellites to space 
?The engine is the workhorse liquid rocket engine powering the second stage of PSLV, 2nd stage and 
the four strap-on stages of GSLV and twin engine core liquid stage of GSLV Mk-III 
?The engine is a liquid-fuel engine which uses N2O4 (Nitrogen T etroxide) propellant  
•
Ramjet 
?It is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming 
air for combustion without a rotating compressor 
?Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites 
as opposed to a normal jet engine, in which the compressor section (the fan blades) compress the air 
?A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed 
where it begins to produce thrust 
? The air ?ow through a ramjet engine is subsonic, or less than the speed of sound 
?
It works most ef?ciently at supersonic speeds around Mach 3 and can operate up to speeds of 
Mach 6 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
However, the ramjet ef?ciency starts to drop when the vehicle reaches hypersonic speeds?  
•
Scramjet (Supersonic-Combustion Ramjet) 
?It is an improvement over the ramjet engine as it ef?ciently operates at hypersonic speeds and 
allows supersonic combustion 
?
These are envisioned to operate at speeds up to at least Mach 15 
?The Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric 
air as the oxidiser 
?With the recent testing of Advanced T echnology Vehicle (ATV), a sounding rocket, India became the 
fourth country to demonstrate the ?ight testing of a scramjet engines  
?The scramjet engine is used only during the atmospheric phase of the rocket’s ?ight  
?Factors like air inlet design, air compressibility, complex ?ows, high temperatures, fuel injection, etc 
– make it really dif?cult to design a suitable scramjet powerplant. Scramjets are highly inef?cient at 
low speeds, with their ef?ciency increasing at supersonic speeds 
?India is the fourth country to demonstrate the ?ight testing of Scramjet Engine after the US, Russia 
and European Space Agency 
?According to ISRO, the development of a Scramjet system is extremely complex as it involves many 
technological challenges, especially relating to mixing of very high speed air (velocity around 1.5 
km/s) with fuel, achieving stable ignition and ?ame holding in addition to ensuring ef?cient 
combustion, within the practical length of the combustor 
?Importance 
?
PSLVs are expendable, meaning that can only be used once, and are designed to carry both fuel 
and oxidizer with for launch. Scramjets use ambient air to burn fuel, thus saving the need to 
carry an oxidizer – thus increasing the payload of a craft 
? Since there are no rotating parts in a scramjet, the chances of failure are also measurably 
reduced 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
ISRO claims that using Avatar for satellite launches will cut down launch costs by half 
? ISRO’s reusable launch vehicle platform, called Avatar, is a concept that is capable of 
carrying out satellite launches – takes off vertically and lands back on a runway 
?
In defence, the next generation of cruise missiles is likely to be powered by scramjets that reach 
hypersonic speeds 
?
Civil aviation could commercialise air-breathing rocket engine technology.   It has a greater 
incentive and a bigger market. Intercontinental ?ights which use scramjets to reach hypersonic 
speeds at the edge of space would cut travel time by a factor in the range of a ?fth to an eighth? ?  
•Dual Mode Ramjet (DMRJ) 
?Type of jet engine where a ramjet transforms into scramjet over Mach 4-8 range, which means it can 
ef?ciently operate both in subsonic and supersonic combustor modes 
•Cryogenic Engine 
?A cryogenic engine/ cryogenic stage is the last stage of space launch vehicles which makes use of 
Cryogenics. Cryogenics is the study of the production and behaviour of materials at extremely low 
temperatures (below -150 degree Centigrade) to lift and place the heavier objects in space 
?Cryogenic rocket stage is more ef?cient and provides more thrust for every kilogram of propellant it 
burns compared to solid and earth-storable liquid propellant rocket stages 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
Speci?c impulse (a measure of the ef?ciency) achievable with cryogenic propellants (liquid 
Hydrogen and liquid Oxygen) is much higher compared to earth storable liquid and solid 
propellants, giving it a substantial payload advantage 
?
Amongst all rocket fuels, hydrogen is known to provide the maximum thrust. But hydrogen, in 
its natural gaseous form, is dif?cult to handle, and, therefore, not used in normal engines in 
rockets like PSLV. However, hydrogen can be used in liquid form 
?Oxygen liqui?es at -183 deg C and Hydrogen at -253 deg C. The propellants, at these low 
temperatures are to be pumped using turbo pumps running at around 40,000 rpm 
?It makes use of Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) as propellants which liquefy at -183 
deg C and -253 deg C respectively. LOX and LH2 are stored in their respective tanks. From there 
they are pumped in to turbo pump by individual booster pumps to ensure a high ?ow rate of 
propellants inside the combustion/thrust chamber. The major components of a cryogenic rocket 
engine are combustion/thrust chamber, igniter, fuel injector, fuel cryo pumps, oxidizer cryo pumps, 
gas turbine, cryo valves, regulators, the fuel tanks and a rocket engine nozzle 
?Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) from the respective tanks are fed by individual 
booster pumps to the main turbopump to ensure a high ?ow rate of propellants into the combustion 
chamber. Thrust control and mixture ratio control are achieved by two independent regulators. Two 
gimballed steering engines provide for control of the stage during its thrusting phase 
?Apart from the complexities in the fabrication of stage tanks, structures, engine and its sub-systems 
and control components, it employs special materials like Aluminum, Titanium, Nickel and their 
alloys, bi-metallic materials and polyimides 
?United States, the erstwhile USSR, France and Japan — had this technology. 
?Importance 
?
It is crucial to providing the extra thrust required by the rocket to carry heavier satellites 
deeper into space 
?
GSLV-MkIII is meant to carry payloads up to four to ?ve tons and that was not possible with 
conventional propellants used by ISRO’s main launch vehicle, called PSLV, which can take 
satellites only up to 2 tons to orbits and that too until orbits of 600-km altitude from the earth’s 
surface 
? It will not just help ISRO probe deeper into space but will also bring it extra revenue, enabling it 
to make commercial launches of heavier satellites 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 5


 
Science of Rocket  
•Satellites are launched into orbit by multi-staged satellite launch vehicles that can be used only once 
(expendable) 
•
They carry oxidiser along with the fuel for combustion to produce thrust. Launch vehicles designed for 
one time use are expensive and their ef?ciency is low because they can carry only 2-4% of their lift-off 
mass to orbit 
?Nearly 70% of the propellant (fuel-oxidiser combination) carried by today’s launch vehicles consists 
of oxidiser. Thus, a launch vehicle must use a propulsion system which can utilise the atmospheric 
oxygen during their ?ight  
?Also if these vehicles are made re-usable, the cost of launching satellites will further come down 
•
Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which 
are being developed by various space agencies 
•
Vikas (VIKram Ambalal Sarabhai) Engine 
?It is a family of liquid fuelled rocket engines conceptualised and designed by Liquid Propulsion 
Systems Centre  
? Design was based on the Viking engine of France  
?It powers all the three satellite launch vehicles of ISRO  
? PSLV, GSLV & GSLV Mk-III 
?The main bene?ciary of the high-thrust Vikas engine is said to be the heavy-lifting GSLV-Mark III 
launcher, which ISRO expects will now put 4,000-kg satellites to space 
?The engine is the workhorse liquid rocket engine powering the second stage of PSLV, 2nd stage and 
the four strap-on stages of GSLV and twin engine core liquid stage of GSLV Mk-III 
?The engine is a liquid-fuel engine which uses N2O4 (Nitrogen T etroxide) propellant  
•
Ramjet 
?It is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming 
air for combustion without a rotating compressor 
?Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites 
as opposed to a normal jet engine, in which the compressor section (the fan blades) compress the air 
?A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed 
where it begins to produce thrust 
? The air ?ow through a ramjet engine is subsonic, or less than the speed of sound 
?
It works most ef?ciently at supersonic speeds around Mach 3 and can operate up to speeds of 
Mach 6 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
However, the ramjet ef?ciency starts to drop when the vehicle reaches hypersonic speeds?  
•
Scramjet (Supersonic-Combustion Ramjet) 
?It is an improvement over the ramjet engine as it ef?ciently operates at hypersonic speeds and 
allows supersonic combustion 
?
These are envisioned to operate at speeds up to at least Mach 15 
?The Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric 
air as the oxidiser 
?With the recent testing of Advanced T echnology Vehicle (ATV), a sounding rocket, India became the 
fourth country to demonstrate the ?ight testing of a scramjet engines  
?The scramjet engine is used only during the atmospheric phase of the rocket’s ?ight  
?Factors like air inlet design, air compressibility, complex ?ows, high temperatures, fuel injection, etc 
– make it really dif?cult to design a suitable scramjet powerplant. Scramjets are highly inef?cient at 
low speeds, with their ef?ciency increasing at supersonic speeds 
?India is the fourth country to demonstrate the ?ight testing of Scramjet Engine after the US, Russia 
and European Space Agency 
?According to ISRO, the development of a Scramjet system is extremely complex as it involves many 
technological challenges, especially relating to mixing of very high speed air (velocity around 1.5 
km/s) with fuel, achieving stable ignition and ?ame holding in addition to ensuring ef?cient 
combustion, within the practical length of the combustor 
?Importance 
?
PSLVs are expendable, meaning that can only be used once, and are designed to carry both fuel 
and oxidizer with for launch. Scramjets use ambient air to burn fuel, thus saving the need to 
carry an oxidizer – thus increasing the payload of a craft 
? Since there are no rotating parts in a scramjet, the chances of failure are also measurably 
reduced 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
ISRO claims that using Avatar for satellite launches will cut down launch costs by half 
? ISRO’s reusable launch vehicle platform, called Avatar, is a concept that is capable of 
carrying out satellite launches – takes off vertically and lands back on a runway 
?
In defence, the next generation of cruise missiles is likely to be powered by scramjets that reach 
hypersonic speeds 
?
Civil aviation could commercialise air-breathing rocket engine technology.   It has a greater 
incentive and a bigger market. Intercontinental ?ights which use scramjets to reach hypersonic 
speeds at the edge of space would cut travel time by a factor in the range of a ?fth to an eighth? ?  
•Dual Mode Ramjet (DMRJ) 
?Type of jet engine where a ramjet transforms into scramjet over Mach 4-8 range, which means it can 
ef?ciently operate both in subsonic and supersonic combustor modes 
•Cryogenic Engine 
?A cryogenic engine/ cryogenic stage is the last stage of space launch vehicles which makes use of 
Cryogenics. Cryogenics is the study of the production and behaviour of materials at extremely low 
temperatures (below -150 degree Centigrade) to lift and place the heavier objects in space 
?Cryogenic rocket stage is more ef?cient and provides more thrust for every kilogram of propellant it 
burns compared to solid and earth-storable liquid propellant rocket stages 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?
Speci?c impulse (a measure of the ef?ciency) achievable with cryogenic propellants (liquid 
Hydrogen and liquid Oxygen) is much higher compared to earth storable liquid and solid 
propellants, giving it a substantial payload advantage 
?
Amongst all rocket fuels, hydrogen is known to provide the maximum thrust. But hydrogen, in 
its natural gaseous form, is dif?cult to handle, and, therefore, not used in normal engines in 
rockets like PSLV. However, hydrogen can be used in liquid form 
?Oxygen liqui?es at -183 deg C and Hydrogen at -253 deg C. The propellants, at these low 
temperatures are to be pumped using turbo pumps running at around 40,000 rpm 
?It makes use of Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) as propellants which liquefy at -183 
deg C and -253 deg C respectively. LOX and LH2 are stored in their respective tanks. From there 
they are pumped in to turbo pump by individual booster pumps to ensure a high ?ow rate of 
propellants inside the combustion/thrust chamber. The major components of a cryogenic rocket 
engine are combustion/thrust chamber, igniter, fuel injector, fuel cryo pumps, oxidizer cryo pumps, 
gas turbine, cryo valves, regulators, the fuel tanks and a rocket engine nozzle 
?Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) from the respective tanks are fed by individual 
booster pumps to the main turbopump to ensure a high ?ow rate of propellants into the combustion 
chamber. Thrust control and mixture ratio control are achieved by two independent regulators. Two 
gimballed steering engines provide for control of the stage during its thrusting phase 
?Apart from the complexities in the fabrication of stage tanks, structures, engine and its sub-systems 
and control components, it employs special materials like Aluminum, Titanium, Nickel and their 
alloys, bi-metallic materials and polyimides 
?United States, the erstwhile USSR, France and Japan — had this technology. 
?Importance 
?
It is crucial to providing the extra thrust required by the rocket to carry heavier satellites 
deeper into space 
?
GSLV-MkIII is meant to carry payloads up to four to ?ve tons and that was not possible with 
conventional propellants used by ISRO’s main launch vehicle, called PSLV, which can take 
satellites only up to 2 tons to orbits and that too until orbits of 600-km altitude from the earth’s 
surface 
? It will not just help ISRO probe deeper into space but will also bring it extra revenue, enabling it 
to make commercial launches of heavier satellites 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
Space Exploration 
•
ASTROSAT  
?It is the ?rst dedicated Indian astronomy mission, launched in 2015, aimed at studying celestial 
sources in X-ray, optical and UV spectral bands simultaneously. The payloads cover the energy 
bands of Ultraviolet (Near and For), limited optical and X-ray regime 
?One of the unique features of AstroSat mission is that it enables the simultaneous multi-wavelength 
observations of various astronomical objects with a single satellite 
?It is a joint project of ISRO and Canadian Space Agency  
?It will observe 
?
Nearby Galaxies: The formation sites of the youngest and most massive stars in the universe 
? Neutron Stars: Behaviour of matter at extreme densities and magnetic ?elds 
? X-ray binaries  
?Why do we need specialised telescopes 
? Our atmosphere absorbs high energy light. So in order to study these rays we need such 
telescopes 
? Except for the visible, near infrared and radio telescopes, all other telescopes need to be 
outside the Earth’s atmosphere 
•Chandrayaan 1 
?The ?rst Indian planetary science and exploration mission, it is a scienti?c investigation of the Moon 
by spacecraft 
?Launched in 2008, it was operational for 312 days  
?Goals 
?
It is aimed at high-resolution Remote Sensing of the Lunar surface in visible, near Infrared, low 
energy X-rays and high-energy X-ray regions  
?
Prepare a 3-D atlas of both near and far side of the moon 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!