SPACE TECHNOLOGY

Content

2. Space Technology
2.1 Basics of Space Technology
2.1.1 What is space
2.1.2. Galaxy
2.1.3. Solar System
2.1.3.1 Sun
2.1.3.2. Structure of sun
2.1.3.3. Plasma
2.1.3.4. Future of sun
2.1.4 Evolution of Stars
2.1.5 Planets
2.1.5.1 Definition
2.1.5.2 Dwarf planet
2.1.5.3 Mars
2.1.6 Asteroids, comets and meteors
2.1.6.1 Definition
2.1.6.2 Leonid Meteor Shower
2.1.6.3 Kuiper belt
2.1.6.4 Oort Cloud
2.2. Basic Concept
2.2.1 UN convention on space
2.2.2. Space Exploration Programme
2.2.3. Space Institutions in India
2.2.4. Concept of Black holes
2.2.4.1 Singularity
2.2.4.2. Event horizon
2.2.4.3 Wormholes
2.2.4.5 Entanglement
2.2.5 Gravitational Waves
2.3 Satellites
2.3.1 Need for Satellite
2.3.2 Structure of satellites
2.3.3 Types of satellites
2.3.3.1 Communication satellite
2.3.3.2 Remote sensing satellites
2.3.3.3 Navigation satellites
2.3.3.4 Space exploration satellites
2.4 Orbit
2.4.1 definition
2.4.2 Types of space orbits
2.4.2.1 Low Earth orbits
2.4.2.2. Geostationary orbits
 2.4.2.3 Medium Earth orbit
2.4.2.4 Polar orbit
2.4.2.5 Sun-synchronous orbit
2.4.2.6 Transfer orbit
2.5 Space Missions
2.5.1 Missions to solar system
2.5.1.1. Sun Missions
2.5.1.2 Missions to Mercury
2.5.1.3 Missions to Venus
2.5.1.4 Missions to Mars
2.5.1.5 Missions to Jupiter
2.5.1.6 Missions to Saturn
2.5.1.7 Missions to Uranus, Neptune
2.5.1.8 Missions to Asteroids
2.5.2 Moon Missions
2.5.2 Missions to Universe
2.5.3 Human Missions
2.6 Launch Vehicles
2.6.1 Global
2.6.2. Indian
2.6.2.1 Evolution of launch vehicles
2.6.2.2 PSLV
2.6.2.3 GSLV
2.6.2.4 SSLV
2.6.3 Engines
2.7. Space station
2.7.1 ISS
2.7.2 China’s Space station
2.7.3 India’s plan
2.8. Positioning System
2.8.1 GPS
2.8.2 NAVIC
2.9 ISRO’s Contribution

2.1 Basics of Space Technology

2.1.1. What is Space?

Space is a 3-d vacant area, a void between the celestial bodies containing a very low density of
particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation,
magnetic fields, neutrino dust and cosmic rays.

Space below the Karman line is Aeronautical space and outer space above the Karman line is
Astronautical Space. Karman Line refers to a 100 Km line.

Do you know?
Theoretically, three satellites In a Geostationary orbit are sufficient to cover a pan area of the
earth.

2.1.2. Galaxy
Our solar system lies in the Milky Way galaxy. All of the stars in the milky way orbit a
supermassive black hole at the centre of the galaxy.
The nearest galaxy to the milky way is Andromeda. It appears to be on course to collide with the
milky way in about a billion years.
Kepler’s Law

Planets revolve around the sun in an elliptical

path i.e. sun is fixed at the focus of the eclipse.
Speed increases at the pedigree and decreases
at apogee.

2.1.3 Solar System

2.1.3.1 Sun
Sun is a 4.5 billion-year-old star. It may appear like an unchanging/ static source of light
and heat in the sky however, it is a dynamic star i.e. it constantly changes and sends energy
into space. Sun is composed of 75% hydrogen and 25% helium.
It gets energy from the nuclear fusion of hydrogen into helium. Fusion occurs when
protons of hydrogen atoms violently collide in the sun’s core and fuse to form a helium atom.
This process is known as a PP (proton-proton) chain reaction. It emits an enormous amount of
energy, in its core, the sun fuses about 620 million metric tons of hydrogen every second.

For an explanation scan, the QR code

2.1.3.2 Structure of the Sun

Sun is largely divided into divide it up into three main regions
● the Sun's interior,
● the solar atmosphere,
● the visible surface of the Sun which lies between the interior and the atmosphere.

Sun’s Interior is composed of 3 parts namely the core, the radiative zone, and the
convective zone.
The core is at the centre of the sun and is the hottest region, where nuclear fusion reactions
occur.
The radiative zone is named so, as the energy is carried by photons as thermal radiation
outward through this layer.
In the convective zone, the heat moves upward via roiling convection, much like the bubbling
motion in a pot of boiling oatmeal so is the name.

The solar atmosphere is separated by the sun interior’s by a layer called the
photosphere. This photosphere is what we see as the visible "surface" of the Sun. however, it is
not like the surface of a planet.

The lower region of the solar atmosphere is called the chromosphere (chroma means colour) as
it appears bright red when viewed during a solar eclipse. The upper part is called Corona.
These two layers are separated by a thin transition region, where temperatures rise sharply, the
outermost region of the sun’s atmosphere namely the corona is much hotter than the Sun's
surface. Corona gradually turns into the solar wind, a flow of plasma that moves outward
through our solar system into interstellar space. Earth and other planets actually orbit within the
atmosphere of a star.

For more details scan the QR code

Does Sun spin as a solid ball?

It does not spin as a single, solid ball because the sun’s surface is not solid like the earth and
plasma rotates at different speeds on different parts of the sun for example at the equator it
rotates at 25 earth days and at the poles at 36 earth days.
2.1.3.3. Plasma
It is a superheated matter and it’s so hot that electrons are ripped away from the atoms forming
an ionised gas. It is also called the fourth state of matter after solid, liquid and gas. In stars and
other fusion devices, plasma provides the environment in which elements can fuse and yield
energy. In plasma, state atoms can overcome their natural electromagnetic repulsion on
collision and thus release huge amounts of energy. Most of the gas of the sun is actually
plasma.

2.1.3.4. Future of the Sun

● Sun like other stars will run out of energy.
 ● When it will start to die, the sun will expand into a red giant star becoming so large that it
will engulf mercury and venus, before losing its outer layers as a planetary nebula
● It will take 5 billion years or so before it shrinks to becomes a White dwarf.

2.1.4. Evolution of the Sun and other stars

Evolution of stars takes place in two different ways depending upon the mass of stars. Low and
medium stars (<1.44 times the sun), will follow the path to become a white dwarf and if the mass
is >1.44 times the sun then they will follow the path of a neutron star and black hole.

Does Sun spin as a solid ball? Significance of 1.44 Solar Mass

This limit or threshold was given by Indian Subramanyam Chandrashekhar, who proposed it in
1930.
● Nebula
○ It is a cloud made up of gas (mostly hydrogen and helium) and dust in space.
○ They are the birthplaces of stars.
● Protostar
○ It appears like a star, however, the core of the protostar is not hot enough for
nuclear fusion to take place as nuclear fusion occurs only when the initial
temperatures are very high to an extent of a few million degrees Celsius.
○ Heating of the protostar at contraction makes it luminous.
○ They are surrounded by dust which blocks the light that they emit.
● T Tauri star
 ○ It is an intermediate stage between a Protostar and a low-mass main sequence
star like the Sun.
○ It is a young, lightweight star, less than 10 million years old, that is still
undergoing gravitational contraction.
● Main sequence stars
○ These are the stars that are fusing hydrogen atoms to form helium atoms in their
cores.
○ The sun is a main sequence star. About 90% of stars in the universe are
main-sequence stars.
● Red dwarf
○ They are the faintest main sequence stars with less than 1/1000th the brightness
of the Sun.
○ Low luminosity makes them invisible to the naked eye.
○ They are smaller in size than the sun and have a surface temperature of about
4000 ֯C.
○ The nearest star to the Sun named Proxima Centauri, is a red dwarf.
● Red giant
○ When the sun runs out of hydrogen fuel at its centre, a red giant is formed.
○ In this stage, it still fuses hydrogen into helium in a shell surrounding the core (a
hot, dense degenerate helium core).
○ They have diameters between 10 and 100 times that of the Sun.
○ Their surface temperature is lower than that of the Sun, despite of that it is
extremely bright.
○ Red giants can turn helium at their core into heavy elements like carbon.
○ However, in red giant stars, most stars are not massive enough to create the
pressures and heat necessary to burn heavy elements, so fusion and heat
production stops.
● Red Supergiant
○ With the condensation of a red giant star, it further heats up and thus burning the
last of its hydrogen and causing the star’s outer layers to expand outward.
○ A very large red giant star is often called Red Supergiant.
● Planetary Nebula
○ The outer layer of gas and dust is called the Planetary nebula.They are lost when
the star changes from a red giant to a white dwarf.
● White dwarf
○ A very small, hot star is called White Dwarf. It is the last stage in the life cycle of
a star like the Sun.
○ They are the remains of normal stars, whose nuclear energy supplies have been
used up.
○ White dwarf consists of degenerate matter with a very high density due to
gravitational effects.
● Nova
○ It occurs on the surface of a white dwarf in a binary system.
 ○ If near proximity to one another, hydrogen can be pulled from the companion
star’s surface onto the white dwarf.
○ When enough material builds up on the surface of the white dwarf, a nuclear
fusion on a white dwarf gets triggered, which causes a sudden brightening of the
star.
● Supernova
○ A supernova refers to the explosive death of a star and it often results in the star
obtaining the brightness of 100 million suns for a short time period.
○ The extremely luminous burst of radiation expels the star’s material at a great
velocity which in turn drives a shock wave into the surrounding interstellar
medium.
○ These waves trigger condensation, a nebula paving the way for the birth of a new
star.
○ Supernovae is a source of a great proportion of primary cosmic rays.
● Black dwarf
○ Black dwarf is the last stage of stellar evolution.
○ A black dwarf is a sufficiently cooled white dwarf that it no longer emits significant
heat or light.
○ No black dwarfs are expected to exist in the universe yet.
● Brown Dwarfs
○ Objects which are too large to be called planets and too small to be stars are
brown dwarfs.
○ They form in the same way that stars do i.e. from a collapsing cloud of gas and
dust.
○ In brown dwarfs as the cloud collapses, the core is not dense enough to trigger
nuclear fusion.
● Neutron stars
○ Neutron stars are composed mainly of neutrons and are produced after a
supernova, forcing the protons and electrons to combine to produce a neutron
star.
○ Neutron stars are extremely dense.
○ If the mass of a neutron star is any greater, its gravity will be so strong that it will
shrink further to become a black hole.
● Black holes
○ Black holes form from massive stars at the end of their lifetimes
○ The gravitational pull in a black hole is so great that nothing can escape from it,
not even light.
○ The density of matter in a black hole is infinite.
○ Black holes distort the space around them.
○ They also have the potential to suck neighbouring matter into them including
stars.

2.1.5 Planets
2.1.5.1 Definition: The most recent definition of a planet was adopted by International
Astronomical Union in 2006. It says a planet must do 3 things
1. It must orbit a star (Sun).
2. It must be big enough to have sufficient gravity to force it into a spherical shape.
3. It must be big enough that gravity cleared away any other objects of similar size near its
orbit around the sun.

2.1.5.2 Dwarf planets

As per IAU, a dwarf planet is a celestial body that orbits the sun and has enough mass to
assume a nearly round shape. Further, it has not cleared the neighbourhood around its orbit and
is not a moon. The five best-known dwarf planets are
● Ceres,
● Pluto,
● Makemake,
● Haumea,
● Eris.
Ceres lies in the main asteroid belt and the remaining 4 lies in the Kuiper Belt.

Interesting facts about various planets

● Mercury: It is the smallest and fastest planet. Though it is nearest to the sun it is not
the hottest planet because the atmosphere is very thin to hold the heat.
● Venus: It is often called Earth’s twin because it’s similar in size and density. Venus has
a thick, toxic atmosphere filled with carbon dioxide, thus it’s the hottest planet. The
thick, yellowish clouds of sulfuric acid trap heat, causing a runaway greenhouse effect.
● Earth: It is the fifth largest planet in the solar system, and it is the only planet in our
solar system with liquid water on the surface.
● Mars: It is a dusty, cold, desert-like planet. It is also called Red Planet.
● Jupiter: Jupiter is the largest planet in the solar system and it is more than twice as
massive as all the other planets combined.
● Saturn: It is the second-largest planet in our solar system and is the only planet to
have rings made of chunks of ice and rock.
● Uranus: rotates at a nearly 90-degree angle from the plane of its orbit and this unique
tilt makes Uranus appear to spin on its side
● Neptune: It is a dark, cold, and whipped by supersonic winds, ice giant planet.

2.1.5.3 Mars
Mars is a dusty cold desert with a very thin atmosphere, mostly composed of CO2,
Argon, nitrogen and a small amount of oxygen and water vapour. It is a dynamic planet with
seasons polar ice caps canyons and extinct volcanoes.
It is also called red planet due to the presence of iron minerals on the martian surface
which is oxidised. It is among the most explored body in our solar system. Mars has two moons
namely Phobos and Deimos.
Various Mars exploration Missions
● India: Mangalyaan
● NASA:
○ 2 rovers: Perseverance( 2021) and Curiosity
○ 1 lander: Insight
○ 1 helicopter: Ingenuity.
● UAE: Hope orbiter (Feb 2021)

2.1.6. Asteroids, Comets and Meteors

2.1.6.1 Definition

● An asteroid is a rocky object that orbits the Sun. Asteroids are smaller than a planet,
but they are larger than meteoroids (pebble sized). Some Asteroids go in front of and
behind jupiter, these asteroids are called Trojan Asteroids.
● Comets are small icy dirt balls which orbit around the Sun. comets are made of ice and
dust whereas asteroids are made of rock.
● A meteor is a space rock or meteoroid which enters Earth's atmosphere. It burns up on
entering the atmosphere and creates a streak of light in the sky which is often called a
"shooting star". When Earth encounters many meteoroids at once it is called a meteor
shower. These bodies are like fossil records of planetary evolution.

2.1.6.2 Leonid Meteor Shower

It is formed by the debris from a small comet called 55P/Tempel-Tuttle in the
constellation Leo, which takes 33 years to orbit the sun. The last Leonid meteor storm took
place in 2002.
 ● The Leonids are also called fireballs (because of their bright colours) and earth grazer
meteors (they streak close to the horizon).
● They are the fastest meteors which typically travel at speeds of 71 km per second,
although the rates are often as low as 15 meteors per hour.

2.1.6.3. Kuiper Belt

It is a ring of icy bodies outside Neptune’s orbit. Arrokoth (recently Pluto is present in Kuiper
Belt. The Kuiper belt is a source of comets.

2.1.6.4. Oort Cloud

It refers to the boundary of the sun’s gravitational influence. It has never been directly observed.
It is made up of icy pieces of space debris. Another source of comets is the Oort cloud, where
most long-period comets in highly tilted orbits come from.

Previous Year Question

2022
Q1: If a major solar storm (solar flare) reaches the Earth, which of the following are the possible
effects on the Earth ?.
1. GPS and navigation systems could fail.
2. Tsunamis could occur in equatorial regions.
3. Power grids could be damaged.
4. Intense auroras could occur over much of the Earth.
5. Forest fires could take place over much of the planet.
6. Orbits of the satellites could be disturbed.
 7. Shortwave radio communication of the aircraft flying over polar regions could be
interrupted.
Select the correct answer using the code given below:
(a) 1, 2, 4 and 5 only
(b) 2, 3, 5, 6 and 7 only
(c) 1, 3, 4, 6 and 7 only
(d) 1, 2, 3,4, 5, 6 and 7
Answer (c)

2011
Q2: What is difference between asteroids and comets?
1. Asteroids are small rocky planetoids, while comets are formed of frozen gases held
together by rocky and metallic material.
2. Asteroids are found mostly between the orbits of Jupiter and Mars, while comets are
found mostly between Venus and mercury.
3. Comets show perceptible glowing tails, while asteroids do not.
Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 3 only
(d) 1, 2 and 3

Q3: An artificial satellite orbiting around the Earth does not fall down. This is so because the
attraction of Earth
(a) does not exist at a such distance
(b) is neutralized by the attraction of the moon
(c) provides the necessary speed for its steady motion
(d) provides the necessary acceleration for its motion

Answers:
1() 2() 3()

2.2. Basic Concepts

2.2.1 UN Convention on Space

To conduct space operations and to keep it free and open, the UN constituted a committee on
the peaceful use of space and a few conventions were laid out

1. Outer Space Treaty,1967

○ The exploration and use of outer space (astronautical space) shall be carried out
for the benefit and in the interests of all countries and shall be available for all
mankind.
 ○ Outer space shall be free for exploration by all States.
○ Outer space shall receive any claim of sovereignty, by any means.
○ States are prohibited to place nuclear weapons or other weapons of mass
destruction in space.
○ the Moon and other celestial bodies should be used for peaceful purposes.
2. Rescue Agreement, 1968: Members are supposed to participate in the rescue
operation of astronauts/vehicles.
3. Moon Treaty 1979: The Moon and its natural resources are the common heritage of
mankind and an international regime should be established to govern the exploitation of
such resources.

2.2.2. History of Space Exploration

● 1935: EXPLORAR I: it was the first satellite/ hot air balloon by the US.
● 1957: Russia launched the first artificial satellite named SPUTNIK
● 1969: APOLLO 11 was the first man mission to the moon by the US, Commander Neil
Armstrong landed on the moon on this flight.
● 1971: Salyut Programme was the first outer space station set up by Russia
● Skylab was the US’s Space Station.

India’s Space exploration programme

● 1954 marks the beginning of the Indian Space Program via the establishment of the
Department of Atomic Energy with Humi Jehangir Bhabha as secretary.
● Space research initiated with Dr Vikram Sarabhai establishing a Physical research lab in
Ahemdabad.
● 1962: INCOSPAR (Indian National Committee for Space Research) was established
by Bhabha with Sarabhai as Chairman INCOSPAR.

2.2.3 The Space Institutions in India

ISRO: Indian Space Research Organisation:

● ISRO was set up in 1969.
● It was bought under the Department of Space in 1972 which is under the chairman of the
Prime Minister’s Office i.e. Prime Minister.
● Aim: To harness space technology for National Development.
● Headquarters of ISRO is in Bengaluru.

ISRO Satellite Centre (ISAC)

● The U R Rao Satellite Centre (URSC), formerly called ISRO Satellite Centre (ISAC) is an
Indian Space Research Organisation centre for the design, development, and
construction of Indian satellites.
● Headquarters is in Bengaluru.

SAC: Space Application Centre

 ● It is responsible for developing space-borne and air-borne instruments/payloads and
their applications for national development and societal benefits.
● It is located in Ahmedabad.

ISTRAC: ISRO Telemetry, Tracking and Command Network

● It is responsible for providing tracking support for all the satellite and launch
vehicle missions of ISRO.
● It carries out mission operations of all operational remote sensing and scientific
satellites, providing Telemetry, Tracking and Command (TTC) services from
launch vehicle lift-off till injection of the satellite into orbit.
● Also to estimate its preliminary orbit in space and hardware and software
development activities that enhance the capabilities of ISTRAC for providing
flawless TTC services.
● The Main centre is located in Bangaluru.

Master Control Facility

● It is located in Hassan, Karnataka and Bhopal, Madhya Pradesh.
● It controls all geostationary satellites at
○ Initial orbit raising: ensure the satellite is revolving in its circular orbit.
○ Inorbit payload testing: all payload in place.
● On-orbit operation throughout their life.

Which is the right place for a space research station?

1. Launch vehicles should be as close to the equator as possible as the speed of
earth at the equator is 400 m/s more than that at the poles.
2. Direction should be west to east that is in that of earth.
3. If at all, it should fall in no habitat zone so the east coast is preferable.
4. In the case of geostationary satellites sent from the equator will save fuel
whereas in RSS it cannot be saved.

Vikram Sarabhai Space Centre (VSSC):

It is responsible for the design and development of launch vehicles and also for the research
and development of propellents as well.
Satish Dhawan Space Centre (SDSC)
● It is located at Sriharikota
● It act as a launch centre primarily for Lower Earth Orbit (LEO), GTO (geostationary
transfer orbit) and polar orbit
Liquid Propulsion System Centre
● It is responsible for the development of liquid and cryogenic propulsion stages of launch
vehicle and auxiliary propulsion system
● Centre: Valiamala (Kerala), Mahendra Giri, Bengaluru
National Remote Sensing Centre:
 ● Its headquarter is located in Hyderabad
● Its primary role is of data acquisition, processing and dissemination of information to
provide strong support for DM, resource management, traffic management etc.

2.2.4. Black Hole

A black hole is a place in space where the impact of gravity is extremely high and it
pulls so much that even light can not get out from that place. Gravity here is so strong because
the density here is high and the matter has been squeezed into a tiny space.

Visibility
● These black holes are invisible to us as no light can get out.
● Space telescopes with special tools can aid in finding black holes.
● These tools can see how stars that are very close to black holes stage act differently
than other stars.
● Their images can be obtained with the help of gasses swirling around blackhole.

Formation of black holes

● The smallest black holes formed when the universe began.
● Stellar black holes are made when the centre of a very big star falls in upon itself or
collapses. When this happens, it leads to the creation of a supernova.
● Supermassive black holes were made at the same time as their galaxy was formed.

2.2.4.1 Singularity
A singularity is a point in space (generally at the centre of a black hole, however it exists
outside the blackhole as well) where there is a mass with infinite density. This will lead to a
spacetime with an infinite curvature.
Singularities are predicted to exist in black holes by Einstein's theory of general relativity,
however, it doesn't really exist and something needs to replace the singularity.

To know more about space-time, scan the code

2.2.4.2 Event Horizon
It is linked to the object's escape velocity. The radius around a singularity where matter
and energy cannot escape the black hole’s gravity is Event Horizon. It is the threshold around
the black hole where the escape velocity surpasses the speed of light.

Escape velocity
is the speed that one would need to exceed to escape the black hole's gravitational pull.
The closer an object is to a black hole, the greater the speed they would need to escape the
massive gravity of a black hole.

As per Einstein's theory of special relativity, nothing can travel faster through space than
the speed of light. This suggests a black hole's event horizon is a point from which nothing can
return. The name Event horizon refers to the impossibility of witnessing any event taking place
inside that border i.e. the horizon beyond which one cannot see.

2.2.4.3 Wormholes

These are theoretical

passages, a kind of loophole
through space-time that could
be shortcuts between two
regions of the Universe that
might allow one to traverse
vast distances in a much
shorter time. Wormholes are
also predicted by Einstein’s
theory of relativity, however,
none have ever been found in nature. They act as a bridge between two points in space. These
shortcuts are also called Einstein- Rosen Bridges or wormholes.

2.2.4.4.Entanglement
It is a peculiar, quantum phenomenon involving particles, When particles are put into an
entangled state, the measurement of one particle seems to affect the other particle immediately.
This happens case even when the two particles are too far apart for causation to be possible.

2.2.5 Gravitational Waves

● These are 'ripples' in space-time which are caused by some of the most violent and
energetic processes in the Universe.
● In 1916, Albert Einstein predicted the existence of gravitational waves in his general
theory of relativity.
● It showed that massive accelerating objects such as neutron stars or black holes orbiting
each other will disrupt space-time in such a way that 'waves' of undulating space-time
would propagate in all directions away from the source.
● These ripples thus create would travel at the speed of light, carrying with them
information about their origins, as well as clues to the nature of gravity itself.
● The strongest gravitational waves are produced by events such as colliding black holes,
supernovae and colliding neutron stars.
● Other such waves are assumed to be caused by the rotation of neutron stars that are not
perfect spheres, and possibly even the remnants of gravitational radiation created by the
Big Bang.

To read more about gravitational waves scan the code

Previous Year Questions

2019
Q1: Recently, Scientists observed the merger of giant black holes billions of light-years away
from the Earth. What is the significance of this observation?
(a) 'Higgs boson particles' were detected
(b) Gravitational waves' were detected.
(c) The possibility of intergalactic space travel through a 'wormhole' was confirmed.
(d) It enabled the scientists to understand 'singularity'.

2017
Q2: What is the purpose of the ‘evolved Laser Interferometer Space Antenna’ (eLISA) project?
(a) To detect neutrinos
(b) To detect gravitational waves
(c) To detect the effectiveness of missile defence system
(d) To study the effect of solar flares on our communication systems

Answers
1(b) 2(b)

2.3 Satellites
 Satellite is an artificial object which has been intentionally placed into orbit. They are
called artificial satellites to distinguish them from natural satellites like the moon.

Communication through satellite:

The communication going from a satellite to the ground is called downlink
communication. The communication going from the ground to a satellite it is called
uplink.
When an uplink is being received by the spacecraft and a downlink is being
received by Earth at the same time, the communication is called two-way
communication.
If there is a contract between two satellite link ( pathway of one satellite) then that is
called a cross-link.

2.3.1 Need for Satellite

● Satellites facilitate for Wider coverage area at one point in time, thus aiding in easier
studies.
● Transmission cost through satellites is independent of distance from the centre of
coverage
● It performs a wide gamut of functions such as communication, navigation etc.

Challenges of satellites
● Manufacturing, launch, maintenance etc of satellites are cost intensive.
● Space race has further led to the creation of Space debris.
● Repairing the damage is not possible: ISRO for a fund of 10 crores for outer space
refuelling to prolong its life
● Bandwidth is getting used up.

2.3.2 Structure of satellites

Satellites are largely composed of four structural elements as follows
1. Bus Module
○ It is the main body or structural subsystem of a satellite
on which other elements/ parts of the satellite are
mounted.
○ Attitude control system is composed of a gyroscope and
accelerometer.
○ ACS is defined as controlling the orientation of the axis
of satellites that are orbiting in space
2. Power Source
○ It is either Solar Panels or batteries.
○ Solar panels contain photovoltaic cells, which convert solar energy into
mechanical and chemical energy
○ Need of solar panels, in satellite one part is illuminated by the sun another half
which is dark space use chemical energy
○ However, it has issues as the large surface area is vulnerable to space debris.
 3. Communication System
○ It consists of a receiver, transmitter and one/more radio antennae to perform
telemetry, tracking and command.
4. Mission Specific equipment or specific payloads such as transponders for
communication satellites, optical sensors, infrared sensors, and spectrographs for
remote sensing satellites.

Bands Frequency range Bandwidth Application

(Giga HZ) (Giga HZ)
L 1- 2 1 Mobile satellite service (MSS)

S 2-4 2 MSS and deep space research

C 4-8 4 Fixed satellite service

X 8-12.5 4.5 FSS, military communication,
territorial earth exploration

KU 12.5-18 5.5 Broadcasting

K 18-26.5 8.5 FSS
Ka 26.5- 40 13.5 FSS

2.3.3 Types of satellites

2.3.3.1 Communication satellite
 Communication satellite allows radio, and telephone transmissions to be sent live
anywhere in the world. Before the inception of communication, satellite transmissions were
difficult for long distances as the signal which travels in a straight line could not bend around the
earth to reach the destination.

These satellites are Geostationary satellites. They communicate by using radio waves
to send signals to the antennas on the Earth. The antennas then capture those signals and process
the information coming from those signals.

Communication satellites of India

● INSAT series
● GSAT series
Satellites

Name of the satellite Feature

INSAT series of are hybrid satellites i.e. they can be used for communication and
satellites meteorological purposes

1st generation Insat 1A, 1B, 1C, 1D

2nd generation Insat 2A- 2E

3rd generation Insat 3A- 3E

INSAT 3D ● Exclusively Meteorological Satellite

● launched in 2013, by Ariane-5 from French Guiana
● Launched In geostationary orbit
● It replaced Kalpana -1 and INSAT 3A (engaged in
weather forecasting)
● Life ended in 2020

INSAT 3DR ● R stands for relaunch

● Sequel to 3D
● Also exclusively meteorological satellite

4th generation: ● 4A: for DTH services with payload in Ku and C band
● 4B: similar to 4B
● 4C: failed
● 4CR: launched in 2007

GSAT series of Are exclusively communication satellite

satellites

GSAT 12 ● It was launched by PSLV C17 in 2011

● Core team of ALL WOMEN member
GSAT 9 ● Launch in May 2017 by GSLV F09 in Geostationary orbit
● Transponder: 12 Ku band
● It provides communication application to South Asia
● First satellite to use electric propulsion

● Launched in June 2017 in GSLV MKIII D1 (heaviest

GSAT 19 indina launch vehicle)
● It was placed in geosationary orbit
● Ku and Ka band transponders
● It has indegenous lithium ion battery
● Payloads:
○ Geostatioanry radiation spectrometer (GRASP):
To monitor and study the nature of charged
particles and influence of space radiation on
satellites

It was launched in June 2017 by Ariane 5 (French Guiana) in

GSAT 17 geostationary orbit for the purpose of search and rescue services

It is a S band communication satellite and has S band unfurlable

GSAT 6A antenna of 6 metres which is being used for stratergic purpose
● For armed forces
● 10 year life span, however it was lost in space
● It used Vikas Engine which is a liquid propellent based
rocket engine, launched through GSLV Mk II (F08)
● It is the third satellite for strategic purposes after
○ First in 2013: GSAT-7 for Navy
○ Second in 2016: GSAT 6 for Indian army

● It is Heaviest indigenous satellite weighs 3500 kg and is a

GSAT 29 communication satellite for high quality internet services
● Life is 10 years
● It is placed In geosynchronous orbit via GSLV- MK 111
● It will provide digital communication in remote villages’
resource centers and thus plug-in digital divide.
● It is one of the planned India HTS quartet (high
throughput satellites)
● HTS Quartet
○ GSAT-19 sent up in June 2017
○ 2nd: GSAT 29
○ 3rd: GSAT11
 GSAT: 7A ● GSAT 7 for Indian Navy
● Life of 8 years to provide communication capability to the
Indian air force in Ku- band
● Space vehicle is placed in geostationary orbit
● It has an indigenous cryogenic upper stage of 3 stages

● It is India’s heaviest satellite, more than 4 tonnes,

GSAT 11 however, it was recalled from French guinea before
launch.
● Expected to boost broadband connectivity
● Advanced satellite communication with multi-spot beams
covering the Indian mainland and islands
● Promises to bridge the urban-rural digital divide

GSAT 30 ● India’s telecommunication satellite was successfully

launched into a Geosynchronous Transfer Orbit
(GTO)
● Will replace INSAT 4A to ensure continuity of several
services
● Will provide high-quality TV, telecommunication and
broadcasting service

GSAT 31 ● It weighs around 2500 kg and will replace INSAT 4Cr

● It will be launched from French Guiana, on board
Arianespace
● KU BAND transponder
● The satellite provides Indian mainland and island
coverage.
● Operational life: 15 years

2.3.3.2 Remote sensing satellites

Remote sensing is the method of detecting and observing the physical characteristics of
a region by measuring its reflected and emitted radiation in different wavelengths at a distance
from a satellite. The output of a remote-sensing satellite is usually in form of an image. It is done
either by recording or by real sensing devices.

Sensors used in remote sensing satellite:

● Active sensing:
○ In this sensors use their own source of energy
○ Active system of sensing has the ability to obtain measurements anytime,
regardless of the time of day or season
 ○ It requires the generation of a fairly large amount of energy to adequately
illuminate targets.
○ Examples: Laser fluorosensor and a synthetic aperture radar (SAR).
● Passive sensing:
○ It refers to receiving solar electromagnetic radiation reflected from the earth’s
surface.
○ Except for thermal sensors, passive sensors cannot be used at night.
Application
● It helps in the collection of valuable data in a short period of resources.
● It helps in better resource management and accelerating national development.
● It has the potential to improve agriculture, mineral prospecting, water resources, the
environment, forestry etc.

Payloads:
● Multispectral scanner: It collects data over a variety of wavelengths from 0.5
micrometres- 1.1 micrometres.
● Linear imaging self-scanning camera (LISS):
○ it is the commonest payload in India
○ Due to Higher oscillation in the mirror it covers the higher swath value
○ Provides images in visible and infrared regions.
● Panchromatic camera:
○ It provides imaging in visible frequency.
○ It covers a swath of around 70 km
● Wide field scanner (WiFS)
○ It covers a swath of 780 km
○ For example wifi
○ It can cover the entire subcontinent in 5 days

Remote Sensing Satellites

Name of the satellite Feature

IRS series of satellites It was started in 1988

Presently 13 operational satellites are present in
sun-synchronous orbit

Resourcesat I: Launched in 2003 in PSLV-C5 for the purpose of

natural resource management, agriculture, forestry,
geological exploration.

II: Launched in 2011 by PSLV: C16

IIA: launched in December 2016 by PSLV C36

 CARTOSAT: 1, 2, 2A, 2B: Variants: 1, 2, 2A, 2B
I: Launched in 2005 for the purpose of large scale
mapping, 3-d terrain modelling, land use GIS
application
II: launched in 2007

CARTOSAT 2 SERIES Satellite 2A was launched specifically for military purposes in

2008.

RISAT (1 and 2) These are RADAR imaging satellites with a synthetic

aperture RADAR meant for wider coverage as a
payload.

RISAT 1:
● It is a C band satellite launched in 2012 and the
first RSS to work in this region.
● Purpose: natural resource management and
Prediction and prevention of flood-related
damage.

RISAT 2:
● It is the first and only RSS to work in the X band
region.
● Mandate:
○ Monitor Indian border towards air
infiltration and anti-terror operation
○ search and rescue mission during
Disaster
○ Made in the contribution of ISRAEL and
in return TECSAR was launched

● It is an India- France collaboration.

Megha Tropiques ● Launched in 2011 via PSLV C 18
● It studies heat exchange that happens in the
tropical regions for water cycle

Satellite with ARgos and ALtika ● It was launched in 2013 via PSLV C20
(SARAL) ● It is a joint Indo-French collaboration aim to
study ocean circulation and sea surface
elevation.

Oceansat and ● Payload in oceansat 1, 2, and Scatsat 1) ocean

Scatsat colour monitor: it studies physical and biological
characteristics of ocean surface such as
 ○ surface temperature
○ Chlorophyll concentration in
phytoplankton
○ Aerosol concentration above surfaces
○ Suspended particulate in liquid and solid
● Findings include Coastal characteristic and
Fishing zone weather prediction.
● Additional payload is Scatterometer for an early
warning system for cyclone prediction.

2.3.3.3 Navigation Satellites

A system of satellites that provides autonomous geo-spatial positioning with global coverage.
Present-day Navigation systems include GPS and GLONASS (Russia). This will be dealt with
in detail in chapter 2.8.

Sounding Rockets
● There are certain important regions of space that are too low for satellites and so
sounding rockets provide the only platform that can carry out measurements in these
regions.
● Sounding rockets carry scientific instruments into this space along a parabolic
trajectory.
● Their overall time in space is brief typically 5-20 minutes and at lower vehicle speeds.

2.3.3.4 Space exploration satellites

These are not really satellites but are probing. Space probes send back detailed pictures and
atmospheric data of planets and other stellar phenomena. They are built to last because it takes
so long for the satellite to reach their destinations. For example Chandrayaan1, Mars Orbiter
Mission (Mangalyaan) etc. of India. This will be dealt with in detail in chapter 2.5.

Previous Year Questions

2019
Q1. For the measurement/estimation of which of the following are satellite images/remote
sensing data used?
 1. Chlorophyll content in the vegetation of a specific location
2. Greenhouse gas emissions from rice paddies of a specific location
3. Land surface temperatures of a specific location
Select the correct answer using the code given below.
(a) 1 Only
(b) 2 and 3 only
(c) 3 only
(d) 1, 2 and 3

2016
Q2: With reference to ‘Astrosat’, the astronomical observatory launched by India, which of the
following statement(s) is/are correct?
1. Other than USA and Russia, India is the only country to have launched a similar
observatory into space.
2. Astrosat is a 2000 kg satellite placed in an orbit at 1650 km above the surface of the
Earth.
Select the correct answer using the codes given below.
(a) 1 only
(b) 2 only
(c) Both1 and 2
(d) Neither 1 nor 2

2015
Q3: What is ‘Greased Lightning-10 (GL-10)’, recently in the news?
(a) Electric plane tested by NASA
(b) Solar-powered two-seater aircraft designed by Japan
(c) Space observatory launched by China
(d) Reusable rocket designed by ISRO

Q4: In which of the following activities are Indian Remote Sensing (IRS) satellites used?
1. Assessment of crop productivity
2. Locating groundwater resources
3. Mineral exploration
4. Telecommunications
5. Traffic studies
Select the correct answer using the codes given below.
(a) 1, 2 and 3 only
(b) 4 and 5 only
(c) 1 and 2 only
(d) 1, 2, 3, 4 and 5

Answers
1(d) 2(d) 3(a) 4(a)
2.4 Orbit

2.4.1 Definition
An orbit is the curved path that an object in space (such as a star, planet, moon,
asteroid etc.) takes around another object due to the gravitational pull of the centre object. It is a
regular, repeating path that one object in space takes around another one.
2.4.2 Types of space orbits

2.4.2.1 Low Earth orbits

A low Earth orbit (LEO) is an orbit that is relatively close to the Earth’s surface. It is
normally at an altitude between 160 km to 1000 km above Earth.

Application:
● They are used for satellite imaging.
● It is the orbit used for the International
Space Station (ISS), as it is easier for
astronauts to travel to and from it at a
shorter distance.

Features:
● The satellites in LEO do not always
have to follow a particular path around
Earth in the same way, their plane can
be tilted, thus there are more routes
available LEO is a very commonly
used orbit.
● Satellites in LEO travel at a speed of
around 7.8 km per second. At this
speed, a satellite takes approximately
90 minutes to circle Earth, thus, the ISS travels around Earth about 16 times a day.
● Satellites in LEO alone are not useful for telecommunication, because they move
so fast across the sky. Therefore, it requires a lot of effort to track from ground
stations.

2.4.2.2. Geostationary and Geosynchronous orbits (GEO)

Geostationary orbit is also known as Clarke’s orbit.
Features:
● It circles above the equator from west to east i.e. lies in the equatorial plane.
● It lies at an altitude of 36000 km.
● It travels at the same rate as the earth, so satellites in this orbit will always appear
stationary from the ground.
● Application: satellites in this orbit are used for various forms of telecommunication,
including television. Signals from these satellites can be sent all the way around the
world. Telecommunication requires them to "see" their satellite all time and hence it must
remain stationary in the same positions relative to the Earth's surface.
 ● It is useful for observations of weather conditions.
● Disadvantage of geostationary orbits is the great distance to the Earth, which
reduces the achievable spatial resolution.
Geosynchronous Orbit
● It also lies at an altitude of 36000 km from the surface of the earth.
● It is called geosynchronous orbit because its rotation is synchronised with the rotation of
the earth like the geostationary orbit.
● However the difference is unlike geostationary orbit it can lie at an inclination with the
equatorial plane.
● So there can be numerous geosynchronous orbits.
● Geostationary orbit is also a geosynchronous orbit.

2.4.2.3 Medium Earth orbit

Medium earth orbit is composed of a range of orbits anywhere between low earth orbit (LEO)
and GEO.

Features:
● Like LEO, it also does not need to take specific paths around Earth.
● It is used by a variety of satellites with many different applications.
● It is commonly used by navigation satellites, like the European Galileo system.

The two most common types of Medium earth orbit are

● Semi-synchronous orbit:
● It is a near-circular orbit i.e. low eccentricity which lies at about 20,200 kilometres above
the surface of the earth.
○ A satellite in this orbit takes 12 hours to complete an orbit.
○ Thus, the satellite crosses over the same two spots on the equator every day in
24 hours.
○ This is a consistent and predictable orbit.
 ○ This orbit is used by the Global Positioning System (GPS) satellites.

● Molniya orbit.
○ It was discovered by the Russians. This
orbit works well for observing high
latitudes.
○ They act as a useful alternative to
geostationary orbit as satellites in a GEO
are parked over the equator, so they don’t
work well for far northern or southern
locations, which are always on the edge of
view of geostationary satellites.
○ It combines high inclination (63.4°) with
high eccentricity (0.722) to maximize
viewing time over high latitudes.
○ Each orbit lasts 12 hours, so the slow,
high-altitude portion of the orbit repeats
over the same location every day and
night.

2.4.2.4 Polar orbit

Polar orbits lie at low altitudes between 200 to 1000 km thus, are a type of low Earth
orbit. Satellites in polar orbits usually travel past Earth from north to south rather than from west
to east, passing roughly over Earth's poles.
Satellites in a polar orbit do not have to pass the North and South Pole precisely; even a
deviation within 20 to 30 degrees is still classed as a polar orbit.

2.4.2.5 Sun-synchronous orbit

Sun-synchronous orbit (SSO) is a kind of polar orbit. Satellites in this orbit travelling over
the polar regions are synchronous with the Sun. This means they will always be in the same
‘fixed’ position relative to the Sun. Thus satellite always visits the same spot at the same local
time, for example, passing the coordinates of Delhi every day at the same time.

This constant observation of a point on the Earth at the same time of the day by satellite serves
a number of applications; for example, comparison on how something changes over time like
vegetation changes over months, water changes over years etc. this orbit is also called as
Dawn to Dusk orbit.

A satellite in a Sun-synchronous orbit will be at an altitude of between 600 to 800 km. At

800 km, it will be travelling at a speed of approximately 7.5 km per second.

2.4.2.6 Transfer orbit

Transfer orbits are a special kind of orbit where a satellite is sent before placing it in the
destined orbit. Here, by using relatively little energy from built-in motors, the satellite or
spacecraft can move from one orbit to another. This allows a satellite to reach,a high-altitude
orbit like GEO without actually needing the launch vehicle to go all the way to this altitude, which
would require more effort.

2.4.2.7 Lagrange point

Lagrange Points are those positions in space where

the gravitational forces of a two-body system for
example Sun and the Earth produce enhanced regions
of attraction and repulsion. This pull of two large
masses precisely equals the centripetal force required
for a small object to move with them

L1
● gets an uninterrupted view of the sun without
any eclipse
● Currently Solar and Heliospheric Observatory
Satellite (SOHO) is placed in L1 orbit.
L2
● In L2, a spacecraft is close enough to readily communicate with Earth, can keep Sun,
Earth and Moon behind the spacecraft for solar power and allows one to get the real
picture of deep Space.
● The James Webb Space Telescope will be placed here.

L3
● It is present behind the sun.
● So far no application of this point has been found.

L4 and L5
● Are home to more stable orbits, unlike L1 and L2.

2.4.2.8. Graveyard orbit

A graveyard orbit is also called a junk orbit or disposal orbit. It is an orbit that lies away from
common operational orbits i.e. anything beyond function orbit.

Previous Year questions

Q1: Satellites used for telecommunication relay are kept in a geostationary orbit. A satellite is
said to be in such as orbit when:
1. The orbit is geosynchronous.
 2. The orbit is circular.
3. The orbit lies in the plane of the earth’s equator.
4. The orbit is at an altitude of 22,236 km.
Select the correct answer using the codes given below:
(a) 1, 2 and 3 only
(b) 1, 3 and 4 only
(c) 2 and 4 only
(d) 1, 2, 3 and 4

2.5 Space Missions

Space exploration refers to the use of astronomy and space technology to explore outer
space. While space exploration is carried out mainly by astronomers with telescopes, the
physical exploration of space is conducted both by uncrewed robotic space probes and human
spaceflight. In this chapter, we will discuss the same in detail.

2.5.1 Missions to solar system

Refer to chapter 2.1 for details on the solar system.
2.5.1.1. Sun Missions
Though the sun is not physically explorable with current technology, various probes have
been designed and launched to operate in heliocentric orbit or at one of the Earth–Sun
Lagrange points. Sun explorations mission started in the 1960s with Pioneer 5 by NASA.

Global Solar Missions

● SOHO: a joint project by NASA and ESA
● ACE
● Parker Solar Probe
● IRIS
● MMS
● Hinode
● Stereo
● Solar Orbiter
Solar Mission by India: Aditya-L1

SOHO Mission
● It refers to Solar and Heliospheric Observatory.
● It is a joint project by NASA (National Aeronautics and Space Administration, USA) and
ESA (European Space Agency).
● Mandate: SOHO mission was designed to study the Sun inside out, from its internal
structure to the extensive outer atmosphere to the solar wind that it blows across the
solar system.
● It was launched in December 1995, initially for 2 years but has now been extended till
2025.
● It carried an instrument called LASCO to predict the shape of the solar corona.

ACE Mission
● Advanced Composition Explorer (ACE) is a mission by NASA, which was launched in
august 1997 and is functional till 2024.
● Mandate: It aims to collect and analyze particles of solar, interplanetary, interstellar and
galactic origins. The data will help in understanding the Sun, its interaction with Earth,
and the evolution of the solar system.
● It provides space weather reports and warnings of geomagnetic storms that can disrupt
communications on Earth and harm astronauts in space.
Parker Solar Probe
It is a mission launched in 2018 by NASA and was named after scientist Eugene
Newman Parker who was the first to conceptualise the concept of solar winds in 1950.
Significance: The spacecraft will go through the Sun’s atmosphere as close as 3.8 million
miles to the sun’s surface, into the sun’s corona, more than seven times closer than any
spacecraft has come before after a journey of 7 years and through 7 flybys.

Mandate:
● Help in expanding the understanding of the corona and knowledge of the origin and
evolution of the solar wind by using in situ measurements and the help of images.
● It will improve the ability to forecast changes in Earth's space environment that affect
life and technology on Earth.

Structure:
● It has the equipment to study magnetic fields, plasma and energetic particles, and
image the solar wind.
● The structure is such that it has a cutting-edge heat shield made up of carbon, along
with water-cooled solar panels.
● High precision guidance and autonomy system.

Solar Winds
● The solar wind is created by the outward expansion of plasma (a collection of charged
particles) from the Sun's corona.
● Plasma is continually heated till a point where the Sun's gravity can't hold it anymore.
● Plasma then travels along the magnetic field lines of the sun which extend radially
outward.
● As the Sun rotates (once every 27 days), it winds up its magnetic field lines above its
polar regions into a large rotating spiral which in turn creates a constant stream of wind.
● Such emissions are thought to come from large bright patches called "coronal holes" in
the corona of the sun also known as coronal mass ejection (CME).
Why study solar wind?
● Disturbances in the solar wind can shake Earth's magnetic field and pump energy into
the radiation belts and bring changes to space weather.
● Space weather further can change the orbits of satellites, shorten their lifetimes, or
interfere with onboard electronics.
● The increased knowledge of space weather and its prediction will help in the protection
of satellites.

IRIS
Launched in 2013, Interface Region Imaging Spectrograph (IRIS) is a NASA Small Explorer
Mission to observe how solar material moves, gathers energy, and heats up in Sun's lower
atmosphere.

MMS
Magnetospheric Multiscale Missions or MMS was launched in 2015 to study and investigate
how the sun’s and Earth’s magnetic fields connect and disconnect, explosively transferring
energy from one to another.
The mission uses four identical spacecraft in a pyramid shape to measure magnetic field line
and charged particles in three dimensions.

Magnetic reconnection
It is a fundamental process which taps energy stored in magnetic fields and converts it into heat
and energy. This reconnection is believed to trigger Auroras.

Scan the code to learn about Auroras

Auroras are the colourful light in the sky caused by the sun which occurs when particles from
the sun interact with gases in our atmosphere often seen in areas of the North Pole (Aurora
Borealis) or South Pole ( Aurora Australis).

Formation of Auroras
 ● Storms on the sun that causes events such as Coronal mass ejection and solar wind
from coronal holes to release
charged particles.
● These particles when
interacting with Earth’s (Van
Allen Belts) or any planet’s
(having a magnetic field and
atmosphere) magnetic field
strike atoms and molecules in
Earth’s atmosphere, they
excite those atoms, causing
them to light up.

● If they interact with oxygen

molecules the light is
generally green and red whereas if the molecule is nitrogen then the light is purple.
● These auroras were also witnessed in Jupiter and Saturn.

Hinode
Hinode is a project led by the Japan Aerospace Exploration Agency, or JAXA and is a
collaboration between the space agencies of Japan, the United States, the United Kingdom
and Europe to study the magnetic fields of the Sun in order to improve understanding of what
powers the solar atmosphere and drives solar eruptions

MUSE (Multi-slit Solar Explorer)

It is a mission launched by NASA in 2022 along with Helioswarm mission to investigate the
causes of coronal heating and instability, such as flares and coronal mass ejections, and gain
insight into the basic plasma properties of the corona.

HelioSwarm missions
● It is a constellation or “swarm” of nine spacecraft by NASA which will capture the first
multiscale in-space measurements of fluctuations in the magnetic field and motions of
the solar wind known as solar wind turbulence.
● It consists of one hub spacecraft and eight co-orbiting small satellites that range in
distance from each other and the hub spacecraft.

Solar Orbiter
The Solar Orbiter (SolO) is a Sun-observing satellite developed by the European Space Agency
(ESA). SolO was designed to obtain detailed measurements of the inner heliosphere and the
nascent solar wind. It will also perform close observations of the polar regions of the Sun which
is difficult to do from Earth.

Aditya L1
Aditya L1 is a solar observatory mission which will be launched by the ISRO. It would be placed
into a point in space known as the L1 Lagrange point.
Earlier its anime was Aditya 1 and was renamed Aditya-L1. The Aditya 1 was designed to
observe only the solar corona.

Advantages of placing it in L1
● It will get an uninterrupted view of the sun without any eclipse.
● It will reduce the consumption of fuel.

Launch Vehicle: Aditya L1 will be launched using the Polar Satellite Launch Vehicle (PSLV)
XL with 7 payloads (instruments) on board.

Objective
● To study the Sun’s corona (Visible and Near-infrared rays),
● Also to study the sun's photosphere (soft and hard X-ray) and chromosphere (Ultra
Violet ).
● It will also study solar emissions, solar winds and flares, and Coronal Mass Ejections
(CMEs), and will carry out round-the-clock imaging of the Sun.

2.5.1.2 Missions to Mercury

Mercury is the closest planet to Sun. It is the smallest, densest, and least-explored of the
terrestrial planets. It does not have moons and has no rings as well. It has a thin exosphere
which is composed of oxygen, hydrogen, sodium, helium and potassium.

Various missions to Mercury:

MARINER
● It was the first flyby mission of NASA to
mercury.
Messenger
● It is a NASA Orbiter to Mercury which was
launched in 2004 to understand Mercury,
● Objective:
○ To study Mercury’s chemical
composition, geology, and magnetic
field.
○ To gauze the size and state of the core.
Interior of Mercury
○ To determine the volatile inventory at the poles.
○ To understand the nature of Mercury’s exosphere.
Observation of messenger provided compelling support for the long-held hypothesis that
Mercury harbours abundant water ice and other frozen volatile materials in its shadowed polar
craters.

BepiColombo
 ● It is a joint mission of The European Space Agency (ESA) and the Japan Aerospace
Exploration Agency (JAXA).
● It is named after Italian scientist Giuseppe “Bepi” Colombo (1920-1984) who played a
crucial role in making NASA Mariner 10 mission (1973) to Mercury successful
● It will reach Mercury by 2025.
● It is the first mission of the ESA and JAXA to Mercury.
● It is also the first mission by which two spacecraft were sent to make complementary
measurements of the planet and its environment at the same time.
● Spacecrafts:
○ ESA’s Mercury Planetary Orbiter (MPO)
○ JAXA’s Mercury Magnetospheric Orbiter (MMO, or ‘Mio’).
● The Mercury Transfer Module (MTM) built by ESA will carry the orbiters to Mercury using
a combination of solar electric propulsion and gravity-assisted flybys.
● These two orbiters will also collect data from Venus.
● Challenges to the mission
○ The presence of the sun’s gravity makes it difficult to place a spacecraft into a
stable orbit around the mercury.
○ The spacecraft will also withstand extreme temperatures and solar radiation.

2.5.1.3 Missions to Venus

About Venus
● Venus is the hottest planet in our solar system and is also called Earth’s twin, despite
differences because of similarities in size and density.
● Venus has a thick, toxic atmosphere which is filled with carbon dioxide. It is hidden under
thick, yellowish clouds of sulfuric acid that trap heat, causing a runaway greenhouse
effect.
● Surface temperatures on Venus are about 900 degrees Fahrenheit (475 degrees
Celsius).
● The surface of venus is rusty in colour.

Global missions
● Mariner 2: Venus was the first planet to be explored by a spacecraft in 1962 when
Mariner 2 by NASA successfully flew by and scanned the cloud-covered.
● Magellan mission by NASA which mapped the planet’s surface with radar.
● VENERA, a spacecraft by the soviet union made the most successful landings on the
surface of Venus to date. However, they didn’t survive long due to the extreme heat and
crushing pressure
● Other successful Flyby Venus missions by NASA were Galileo in 1989, Cassini in 1997,
and Messenger in 2004.
 ● More recent Venus missions are ESA’s Venus Express (which orbited from 2006 until
2016) and Japan’s Akatsuki Venus Climate Orbiter (orbiting since 2016).

Future Venus Missions

● VERITAS
○ It was announced by NASA’s or Venus Emissivity, Radio Science, InSAR,
Topography, and Spectroscopy.
○ It will be the first NASA spacecraft to explore Venus since the 1990s.
○ It is expected to launch in December 2027.
○ It will orbit Venus and gather data to find out how the paths of Venus and Earth
diverged, and how Venus lost its potential to be a habitable world.
● DAVINCI
○ It is also a mission by NASA
○ After exploring the top of Venus’s atmosphere, it will drop a probe to the surface.
○ The probe is expected to take measurements and snap up-close images of the
surface.
● EnVision
○ It is a mission by ESA.
○ EnVision will be making detailed observations of Venus.
○ NASA is providing the Synthetic Aperture Radar, called VenSAR, to make
high-resolution measurements of the planet’s surface features.

India’s Venus Expedition

ISRO is expecting to launch the Venus mission Shukrayaan by December 2024.

Shukrayaan-I
● It is planned to be launched on the GSLV Mk II rocket.
● Payloads:
○ Sweden will be providing a scientific instrument to explore the planet.
○ Institute of Space Physics (IRF)’s satellite instrument Venusian Neutrals Analyzer
(VNA) will study how the charged particles from the Sun interact with the
atmosphere and exosphere of the planet.
● Significance of Shukrayaan Venus mission
○ This will the first mission to make an observation of the sub-surface of Venus by
flying the sub-surface radar for the first time. It will go inside the sub-surface of
Venus up to a few hundred meters.
○ The mission will also examine the planet’s atmosphere in infrared, ultraviolet, and
submillimeter wavelengths using specific instruments
○ It will also give insight into the evolution of Earth-like planets and their
atmospheric conditions.
○ It aims at providing a futuristic vision of how climate change can have a massive
impact on a planet.
● Challenges to the Shukrayaan mission
 ○ The thick atmosphere and surface activity on Venus is a difficult to manoeuvre
which is far more complex than on Mars.
○ Going to the depth of the atmosphere to have a deeper understanding is a
challenge.
○ There is a need of high-resolution instruments to penetrate the clouds and
darkness in the Venusian atmosphere.

2.5.1.4 Missions to Mars

About Mars:
● Mars is the fourth planet from the Sun. It is the second-smallest planet in the Solar
System and is about half the size of Earth.
● Similarities of Mars with Earth
○ Both complete rotation around sun in about equal duration of time, it is 24.6
hours for mars and 23.9 hours for Earth.
○ Axis of rotation of Mars is tilted 25 degrees and for Earth axial tilt is 23.4 degrees.
○ Both the planets have s distinct seasons, However, they last longer than seasons
on Earth.
● Days of Mars are called sols which is a short for ‘solar day’.
● Other Features:
○ Mars appears to be Reddish due to oxidation or rusting of iron in the rocks, and
dust of Mars and is thus called Red Planet.
○ It has two moons which are anmed as Phobos and Deimos.

Objectives Behind Mars Exploration:

○ It is believed that Mars was once warm enough to allow water to flow through it,
which means life could have existed there too.
○ It has several Earth like features such as clouds, polar ice caps, volcanoes,
and seasonal weather patterns.
○ No human has set foot on Mars yet because the atmosphere on Mars is very
thin, consisting of mostly carbon dioxide with no breathable oxygen, which
makes it difficult for astronauts to survive there.

India’s Mars Mission: Mangalyaan

About Mars Orbiter Mission

● It was launched in 5th November, 2013 onboard PSLV-C25 with a budget of Rs 450
crore and was successfully inserted into the Martian orbit in September, 2014 in its first
attempt.
● It was India's first interplanetary mission.
● The mission made India the first Asian country, and the first nation in the world to do
so on its first attempt.
● India was the fourth in the world after Roscosmos, NASA (National Aeronautics and
Space Administration), and the European Space Agency, to get to the planet.
Payloads
● It carried 850 kg of fuel and have about 5 payloads
○ Mars Color Camera (MCC): To study the Martian surface and atmosphere since
entering orbit successfully.It was the elliptical orbit of mars which enabled MCC to
take snapshots of the 'Full disc' of Mars at its farthest point and finer details from
the closest point.
○ Other instruments include Thermal Infrared Imaging Spectrometer (TIS),
Methane Sensor for Mars (MSM), Mars Exospheric Neutral Composition
Analyser (MENCA) and Lyman Alpha Photometer (LAP).
● Objectives
○ To study the Martian atmosphere.
○ Exploration of Martian surface features, mineralogy, morphology and atmosphere
using indigenous scientific instruments
○ To develop technologies required in planning, designing, management and
operations of an interplanetary mission.

End of Mangalyaan
● Mars Orbiter craft has lost communication and is non-recoverable and the
Mangalyaan mission has attained end-of-life in 2022
● It was designed for a life-span of six months as a technology demonstrator, the Mars
Orbiter Mission (MOM) has lived for about eight years.
● It ended because of propellant (fuel) exhaustion there were back-to-back eclipses
including one that lasted seven-and-half hours because that satellite has consumed
all the propellant on board. and it lost communication from the ground station.

The future Indian Mars Mission is Mangalyaan 2 which will be launched soon and will only be
an orbiter mission.

ExoMars mission
● The European Space Agency’s ExoMars 2022 mission won’t launch in September, 2022
as planned after the agency suspended all cooperation with Russia’s space program
Roscosmos.
● Earlier, the Russian space agency Roscosmos held that it will not cooperate with
Germany on joint experiments in the Russian segment of the International Space Station
(ISS).

ExoMars 2022 Mission

It is a mission by European Space Agency and Russia in 2012, as NASA dropped out of the
project in 2012.
About:
● ExoMars is a two-stage mission:
○ First stage was launched atop a Proton-M rocket in 2016. The orbiter was
successful however, the test lander failed during its descent to Mars.
○ Second stage consisted of a rover and surface platform.
 ● Objective
○ To check if there has ever been life on Mars and also understand the history
of water on the planet.
○ The rover will drill to the sub-surface of Mars to collect samples from about 2
m of depth.
○ Main aim is to land ESA's rover at a site which has a high potential for finding
well-preserved organic material, particularly from the history of the planet

Tianwen-1
● It is china’s Mars Mission.
● It was launched on a Long March 5 rocket, from the Wenchang launch centre in July
2020.
● It was supported by a Russian spacecraft, that had failed after it did not leave the earth's
orbit and disintegrated over the Pacific Ocean in 2012.
● Recently, it landed on Mars carrying its first Mars rover, Zhurong.
● It became the third country to land on Mars after the US and Soviet Union.

About the Tianwen-1 Mission:

● The Spacecraft consisted of three parts the orbiter, the lander and the rover.
● The orbiter will be in orbit for scientific operations and to relay signals while the
lander-rover combination has made an autonomous descent and landing.
● The lander from Tianwen-1 has touched down on Utopia Planitia. Utopia Planitia is a
large plain in the northern hemisphere of Mars.
● Objective
○ It aims to conduct scientific investigations into the planet’s soil, geological
structure, environment, atmosphere and water.
○ It will be the first to place a ground-penetrating radar on the surface of mars
which will be able to study local geology, as well as rock, ice, and dirt distribution.

Hope Probe
It is the first-ever interplanetary probe by the United Arab Emirates (UAE) and has successfully
entered orbit around Mars.

Features
● It was announced in 2015 with the aim of creating mankind’s first integrated model of the
Mars atmosphere.
● It was developed by UAE scientists in the USA and was launched in July 2020 from the
Tanegashima Space Centre in Japan.
● Hope is expected to complete one orbit around the planet every 55 hours.
● Life of mission is about 2 yeras.
● Payloads:
 ○ Emirates eXploration Imager (EXI) which is a high-resolution camera.
○ Emirates Mars Ultraviolet Spectrometer (EMUS), a far-UV imaging spectrograph.
○ Emirates Mars InfraRed Spectrometer (EMIRS) which will examine temperature
profiles, ice, water vapor and dust in the Martian atmosphere.

Expected Benefits
● It will collect data on Martian climate dynamics which will help scientists in
understanding why Mars' atmosphere is decaying into space.
● Various instruments will collect different data points on the atmosphere to also gauge
seasonal and daily changes.
● It will give information with respect to how energy and particles, like oxygen and
hydrogen, move through the atmosphere of Mars.

Significance
● The UAE becomes the fifth country to reach the Red Planet, joining NASA, the Soviet
Union, the European Space Agency and India.
● It will help UAE in building a knowledge-based economy, leading to more investment
in Science, Technology, Engineering and Mathematics (STEM) for young Emiratis.

Perseverance
It is a rover from the USA. It will be the first step in a decade-long USA-European project to
bring Mars rocks back to Earth to be examined for evidence the planet once harbored
microscopic life.

About Perseverance:
● Perseverance is a six-wheeled rover launched by NASA in 2020, on the surface of Mars
(Jazero Crater).
● Power source: It utilises a Multi-Mission Radioisotope Thermometer Generator which
converts heat into electricity from the natural radioactive decay of Plutonium.

The mandate of Perseverance: To search for signs of ancient microbial life. The rover can also
drill and collect core samples of Martian rock and soil, then store them in sealed tubes for
pickup by a future mission.

Payloads: It carries seven instruments, two microphones and 23 cameras in total in order to
conduct unprecedented science experiments:
● MOXIE: Perseverance carried a unique instrument named MOXIE (Mars Oxygen In
SItu resource utilisation Experiment). MOXIE for the first time manufactured
molecular oxygen on Mars using carbon dioxide from the carbon-dioxide-rich
atmosphere. The environment of mars is composed of 96% carbon dioxide.
 ● Ingenuity
● Perseverance also carried Ingenuity the first-ever helicopter to fly on Mars.
● It uses Jet propulsion which works on the principle of the Third law of Newton.
● Other instruments include:
● Radar Imager for Mars’ Subsurface Experiment (RIMFAX) to provide
high-resolution mapping and look for subsurface water.
● Mastcam- which can help determine mineralogy.
● SuperCam which can provide imaging, chemical composition analysis, and
mineralogy at a distance.
● Planetary Instrument for X-ray Lithochemistry (PIXL)
● Scanning Habitable Environments with Raman & Luminescence for Organics and
Chemicals (SHERLOC) which will be the first UV Raman spectrometer to fly to
the surface of Mars and will provide complementary measurements with other
instruments in the payload.
● Mars Environmental Dynamics Analyzer (MEDA) which will provide
measurements of temperature, wind speed and direction, pressure, relative
humidity, and dust size and shape.

Curiosity
● It is the largest and most capable rover ever
sent to mars.
● It was Launched in 2011 and landed in 2012.
● Soft Landing: Spacecraft descend on a
parachute and then during the final seconds of
landing the landing system fired rockets to
allow it to the rover.
● Power system: It has a plutonium-based power
system and generates electricity from the
radioactive decay of plutonium as discussed
earlier.

Insights is to study the deep interior by NASA.

2.5.1.5 Missions to Jupiter

● Jupiter is the biggest planet in the solar system and is also known as gas giant. The
amount of water in
Jupiter is critical to
understand how the
solar system was
formed.
● Unlike Earth, solar
winds could not blow
away jupiter’s
 hydrogen and helium.
● Jupiter’s atmosphere ought to have evolved from a mechanism other than degassing.
● Due to extreme atmospheric pressure, Jupiter’s hydrogen turned liquid and formed large
oceans.
● Most Mass in the form of heavy metals from the sun has been taken by jupiter.
● They have the strongest aurora emissions in the entire solar system.
● Great Red Spot of jupiter is a giant storm bigger than Earth that has raged for hundreds
of years.
● Moons of Jupiter are lo, Europa, Ganymede, and Callisto.

JUNO
Juno is a space probe by NASA (National Aeronautics and Space Administration) which is
orbiting Jupiter. It was launched on 5th August 2011. It entered Jupiter’s orbit on 5th July 2016,
five years after its launch. Juno was the second NASA mission to Jupiter, the first one was the
Galileo orbiter which ran from 1995 to 2003.

Objectives
● It aims to measure the planet Jupiter’s composition, magnetic and gravity fields, and
polar magnetosphere.
● Investigation of the planet’s formation and origin.
● To find out the amount of water present in its atmosphere.
● To learn if Jupiter has a rocky core or not.
● To figure out Jupiter’s mass distribution and deep winds.

Europa Clipper
It will be launched by NASA in 2024. The module will orbit Jupiter and conduct multiple close
flybys to Europa (the moon of Jupiter) to gather data on the moon’s atmosphere, surface and
interior.

About Europa
● The surface of Europa is mostly solid water ice and contains water beneath it.
● The double ridges are the most common formations on Europa’s surface, like those
seen on Earth’s Greenland ice sheet.

Voyager 1: Voyager 1 is a mission by NASA which was meant to study interstellar space. It
explored the Jupiter and Saturn systems and led to the discovery of new moons, active
volcanoes and much data about the outer solar system.

2.5.1.6 Missions to Saturn

About Saturn
● Saturn is the sixth planet from the Sun and the second-largest planet in our solar system.
 ● It is the only planet to have rings which are made of chunks of ice and rock.
● The recent discovery of 20 new moons of Saturn has made Saturn the planet with the
highest number of moons i.e. 82 moons against 79 moons of Jupiter.

SpaceCraft

Cassini
● Cassini is a joint mission by NASA, the European Space Agency (ESA), and the Italian
Space Agency (ASI).
● It was mandated to study the planet Saturn and its system, including its rings and natural
satellites.
● It comprised both NASA's Cassini space probe and ESA's Huygens lander, which landed
on Saturn's largest moon, Titan in 1997.
● Cassini was the fourth space probe to visit Saturn. It was the first to enter its orbit.
● Finding:
○ The spacecraft has found the presence of methane in the atmosphere of Titan.
○ Enceladus has a liquid ocean with erupting plumes of gas and water which might
harbour the ingredients of life.

2.5.1.7 Missions to Uranus, Neptune

Voyager 2
● It is one of the only probes ever to study Neptune and Uranus during planetary
flybys.
● It is also the second man-made object to leave our planet.
● It visited 4 planets namely Jupiter, Saturn, Uranus and Neptune and became the
first to do so.
● It led to the discovery of 16 moons, as well as phenomena like Neptune’s
mysteriously transient Great Dark Spot, the cracks in Europa’s ice shell, and ring
features at every planet.

2.5.1.8 Missions to Asteroids

About Asteroids
They are rocky objects that orbit the Sun, much smaller than planets and are also called minor
planets.
Categories of Asteroids
● Main Belt of Asteroids
○ They are the first to be found between Mars and Jupiter. There are approximately
1.1-1.9 million asteroids.
● Trojan
○ These are the asteroids that share an orbit with a larger planet.
 ○ NASA figured out the presence of Jupiter, Neptune and Mars trojans. In 2011, it
also reported an Earth trojan.
○ The Jupiter asteroids can be found in “swarms” that lead and follow the planet
Jupiter along its orbit around the Sun.
○ They are believed to be the remnants of the early solar system.
● Near-Earth Asteroids
○ Near-Earth Asteroids (NEA) have orbits that pass close to the Earth and the
ones that cross the Earth’s orbit are called Earth-crossers.
○ More than 10,000 such asteroids are known, of which over 1,400 are
classified as Potentially Hazardous Asteroids (PHAs).

Various Missions

LUCY
● It is a solar-powered mission which is estimated to be over 12 years during which
the spacecraft will visit eight asteroids to deepen the understanding of the “young
solar system”.
● The mission is named after ‘Lucy’, a 3.2 million-year-old ancestor who belonged to
a species of hominins.
● The first encounter of the spacecraft will be with an asteroid Donald Johnson that
lies in the main belt that can be found between Mars and Jupiter. This asteroid is
named so, after the paleoanthropologist who discovered the fossilised remains of
‘Lucy’.
● It will reach the first swarm of trojan asteroids that precede Jupiter by August
2027.
Significance
● These asteroids are believed to be formed from the same material as the planets
nearly 4 billion years ago when the solar system was formed.
● Mandate of the mission:
○ To understand the composition of the diverse asteroids that are a part of
the Trojan asteroid swarms.
○ To determine the mass and densities of the materials and to look for and
study the satellites and rings that may orbit the Trojan asteroids.
● Their study will help in understanding its origins and evolution.

DART Mission

About
● It stands for Double Asteroid Redirection Test.
● It is a mission by NASA.
● It will study the Dimorphos asteroid.
● It is a low-cost spacecraft that has two solar arrays and uses hydrazine propellant
for manoeuvring the spacecraft.
● It carries a high-resolution imager called Didymos Reconnaissance and Asteroid
Camera for Optical Navigation (DRACO) whose Images will be sent to Earth in
real-time and will help study the impact site and surface of Dimorphous.
● It will also carry a small satellite or CubeSat named LICIACube (Light Italian
CubeSat for Imaging of Asteroids).
Objective
● To test the new technology to be prepared in case an asteroid heads towards Earth in
the future.
● The target of the spacecraft is a small moonlet called Dimorphos which orbits a larger
asteroid named Didymos.
● It is also referred to as a suicide mission and the spacecraft will be completely
destroyed.

2.5.2 Moon Missions

India’s Moon Mission

Chandrayaan
● Launched by ISRO, it is only an orbiter.
● It was launched on oct. 22, 2008 onboard PSLV C-11.
● It was launched with a slingshot strategy.
● It had an expected life of 2 years but in 2009 it was trapped in a Solar flare.
● It had 11 payloads.
Scientific Objective of Chandrayaan
● To find out the correct theory of moon origin
 ● To detect the presence of water there
● To find out the presence of mineral and of He (1,3) atoms which might be due to the
presence of solar rays and further can be used for fusion reaction thus a potent solution
for energy crises
● To do 3-D mapping of the moon.
Findings of Moon Mission
● It detected water and hydroxyl ion on the lunar surface predominantly in the polar region.
● It detected characteristic x- rays signal from a lunar surface indicating the presence of
Magnesium, Aluminium, Silica and calcium minerals
● It has done the 3-d mapping of many surface pictures like lunar craters ( depressions)
● It has generated excellent quality high-resolution data further analysis is under
processing.

CHANDRAYAAN II
Chandrayaan II was an integrated 3-in-1 spacecraft of around 4000 kg consisting of an
● The lander: It was detached from the orbiter and soft land on the lunar soil.
● Pragyan (wisdom), and the rover is all equipped with scientific instruments to study the
moon. It was a 6-wheeled solar power device that would roll out, pick up samples of soil
and rock and doc chemical analysis.
● Orbiter of the Moon, Vikram (after Vikram Sarabhai). Pragyan will Transfer data to the
orbiter.
About Chandrayaan 2
● The Chandrayaan-2 was India’s first attempt to land on the lunar surface.
● ISRO had planned the landing on the South Pole of the lunar surface.
● It was conducted for topographical research and mineralogical studies to have a better
understanding of the Moon’s origin and evolution.

Aim
● The main aim of
Chandrayaan 2
was to trace the
location and
abundance of
lunar water on the
moon’s surface.
● The mission was
designed to
expand the lunar
scientific
knowledge
through the
 detailed study of topography, seismography, mineral identification and
distribution, surface chemical composition, thermo-physical characteristics of top
soil and composition of the tenuous lunar atmosphere, leading to a new
understanding of the origin and evolution of the Moon.

Key Payloads
● Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS) to measure the Moon's
X-ray Fluorescence (XRF) spectra to examine the presence of major elements such as
Magnesium, Aluminium, Silicon, Calcium, Titanium, Iron, and Sodium.
● Imaging IR Spectrometer (IIRS) to measure the solar radiation reflected off the Moon's
surface in 256 contiguous spectral bands from a 100 km lunar orbit.
● Chandrayaan 2 Atmospheric Compositional Explorer (CHACE 2) to continue the
CHACE experiment carried out by Chandrayaan 1 with the primary objective to carry out
an in-situ study of the composition and distribution of the lunar neutral exosphere and its
variability.
● Chandra's Surface Thermophysical Experiment (ChaSTE) to measure the vertical
temperature gradient and thermal conductivity of the lunar surface.
● Alpha Particle X-ray Spectrometer and Laser-Induced Breakdown Spectroscope
(APXS) had an objective to determine the elemental composition of the Moon's surface
near the landing site through the X-ray fluorescence spectroscopy technique, where
X-ray or alpha particles are used to excite the surface.

Present status
● It was launched from the Satish Dhawan Space on July 22, 2019, by GSLV Mk III-M1
● The launch was not completely successful, however, the lander Vikram hard-landed in
September last year.
● The orbiter is still in the lunar orbit and has a mission life of seven years.

Chandrayaan 3
● It will be a follow-up of Chandrayaan-2 of July 2019.
● It is proposed in partnership with Japan for 2024.
● This mission will have an orbiter and a landing module. However, the orbiter won’t be
loaded with scientific instruments like the Chandrayaan-2.
● It will be carrying the lander to the moon, overseeing the landing from its orbit and
communicating between the lander and the earth station.

Soft Landing
● It refers to perfect touch down and does not intentionally or otherwise crash.
● Landing on any celestial body is about reducing the speed of the spacecraft.
● Israel’s attempt to soft land on the moon failed at the last minute as the engine failed
and crashed onto the surface.
● Till now only USA, Russia and China have landed safely on the moon.
 ● India’s Vikram Lander had lost contact 2 minutes before it was to soft land on the
moon’s surface and crash landed.

Artemis mission
Artemis programme is a programme by NASA to send people back to the Moon as a first step
toward a future trip to Mars.
● without making a surface landing, like Apollo 8.
● Artemis 3: the Artemis 3 mission will be the first to send astronauts to the Moon. The
southern pole of the Moon, where water in the form of ice has been discovered, will be
the site of NASA's first crewed spaceship landing
● Gateway: A space station named Gateway will be built as part of the Artemis
programme and will orbit the Moon.

2.5.2 Missions to Universe

New Horizon
New Horizons is a mission by NASA, US which is aimed at studying the dwarf planet Pluto, its
moons, and other objects in the Kuiper Belt. it is a region of the solar system that extends from
about 30 AU, near the orbit of Neptune, to about 50 AU from the Sun.

Hubble
About:
● It is a telescope by NASA and is named after the astronomer Edwin Hubble.
● The observatory is the first major optical telescope to be placed in space.
● It has made discoveries in the field of astronomy since its launch (into Low Earth orbit in
1990).
● It is a part of NASA's Great Observatories Program which is a family of four
space-based observatories which include the other missions in the program include the
○ visible-light Spitzer Space Telescope,
○ Compton Gamma-Ray Observatory (CGRO), and
○ the Chandra X-Ray Observatory (CXO)

James Webb
● The James Webb Space Telescope (also called JWST or Webb), an international
collaboration between NASA, the European Space Agency (ESA), and the Canadian
Space Agency (CSA), will be a large infrared telescope with a 6.5-meter primary mirror.
● The telescope was launched on an Ariane 5 rocket from French Guiana in 2021.
● Mandate:
○ It will study every phase in the history of our Universe from the first luminous
glows after the Big Bang.
○ From the formation of solar systems capable of supporting life on planets like
Earth to the evolution of our own Solar System.
2.5.3 Human Missions

Gaganyaan Mission
About Gaganyaan Mission
● Gaganyaan is a mission by the Indian Space Research Organisation (ISRO).
● Under the Gaganyaan three flights will be sent into orbit, two of which will be unmanned
flights and one will be human spaceflight.
● The Gaganyaan system module is called the Orbital Module. It will have three Indian
astronauts, including a woman.
● It will circle Earth at a low earth orbit (LEO) from the earth for 5-7 days.
● It will be launched after the second unmanned mission planned in 2022-23.

Payloads
● Crew module will
carry spacecraft
carrying human
beings.
● Service module is
powered by two liquid
propellant engines.
● It will be equipped
with emergency
escape and
emergency mission
abort.

Launch
It will be launched onboard
GSLV Mk III, also called the
LVM-3 (Launch Vehicle
Mark-3,) which is the
three-stage heavy lift launch
vehicle, that will be used to
launch Gaganyaan as it has
the necessary payload
capability.

Training in Russia:
● Russia will be helping with the training along with the selection of candidates, their
medical examination, and space training.
● The Participants will study in detail the systems of the Soyuz manned spaceship.
● The Soyuz is a Russian spacecraft which carries people and supplies to and from the
space station.
Significance
● It will help in the enhancement of science and technology levels in the country and help
inspire youth.
● Gaganyaan will involve numerous agencies, laboratories, disciplines, industries and
departments.
● It will also help in the improvement of industrial growth.
● A new organisation was recently set up namely IN-SPACe, as part of reforms to
increase private participation in the space sector.
○ To help in the development of technology for social benefits.
○ To help in improving international collaboration.
● Artemis 1: Under this, the Space Launch System rocket will be tested.
Sensors-equipped mannequins will replace the crew members and measure the degrees
of vibration, acceleration, and radiation.
● Artemis 2: Artemis 2 mission is a crewed scheduled for 2024, will orbit the Moon

Previous year Questions

2020
Q1: The experiment will employ a trio of spacecraft flying in formation in the shape of an
equilateral triangle that has sides one million kilometres long, with lasers shining between the
craft”. The experiment in question refers to
(a) Voyager
(b) New Horizons
(c) LISA Pathfinder
(d) Evolved LISA

2018
Q2: What is "Terminal High Altitude Area Defense (THAAD)", sometimes seen in the news?
(a) An Israeli radar system
(b) India's indigenous anti-missile programme
(c) An American anti-missile system
(d) A defence collaboration between Japan and South Korea.

2016
Q3: Consider the following statements
The Mangalyaan launched by ISRO
1. is also called the Mars Orbiter Mission
2. made India the second country to have a spacecraft orbit Mars after USA
3. made India the only country to be successful in making its spacecraft orbit the Mars in its
very first attempt
Which of the statement(s) given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

2014
Q4: Which of the following pair(s) is/are correctly matched?
Spacecraft Purpose
1. Cassini-Huygens: Orbiting Venus and transmitting data to the Earth
2. Messenger: Mapping and investigating the Mercury
3. Voyager 1 & 2: Exploring the outer solar system
Select the correct answer using the codes given below.
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answers
1(d) 2(c) 3(c) 4(b)
2.6 Launch Vehicles
A launch vehicle is a rocket which is designed to carry a payload like a spacecraft or satellites
from the Earth's surface to outer space. These launch vehicles operate from launch pads,
supported by a launch control centre and systems such as vehicle assembly and fueling. India
has two operational Launch Vehicles namely PSLV and GSLV.

2.6.2.1 Evolution of launch vehicles

SLV: Satellite launch vehicle

● It was designed in 1979 and was born out of a need for indigenous satellite launch.
● SLV can carry 40 kg weight to Lower Earth Orbit (LEO).
● It is a four-staged rocket which carries all solid fuel.
● It has no trajectory control
● It is also known as an inertial navigation system or an open loop guidance system as it
depends on inertia post-launch.
● Rohini series of satellites were launched using SLV.
ASLV: Augmented SLV
● It is designed in 1987.
● It has a payload capacity of 150 kg and can carry it to LEO.
● It is a five-stage rocket which carries all solid propulsion.
● It was used for Stretched Rohini series of satellites (SROSS).

PSLV: Polar Satellite Launch vehicle

● It was born out of a need to have versatile capacity.
● It has a payload capacity of 1700 Kg to LEO and 1300 Kg to SSO.
● It carries solid and liquid fuel for propulsion.

GSLV: Geosynchronous Satellite Launch Vehicle

● It has three versions MK-1, MK-II, and Mk-III.
● It carries solid, liquid and cryogenic fuel for propulsion.

2.6.2.2 PSLV
● PSLV is a third-generation launch vehicle of India.
● It is the first Indian launch vehicle to be equipped with a liquid fuel stage.
● It is a four-stage launch vehicle.
○ First stage: a large solid rocket motor with up to 6 strapons.
○ Second stage: an earth-storable liquid stage (Vikas engine)
○ Third stage: A high-performance solid rocket motor made of kevlar
○ Fourth stage: is a liquid stage
● Its first successful flight was in October 1994. It carried 39 consecutively successful
missions by June 2017
 ● Chandrayaan-1 in 2008 and Mars Orbiter Spacecraft in 2013 was launched onboard
PSLV.
● Polar satellite launch vehicle can send a satellite to polar (remote sensing satellites)
orbits and also to GTO
● It was also used to place RSS into Low earth sun-synchronous orbits.

Variants of PSLV

Name of Variants Features of PSLV

PSLV-CA ● CA stands for core alone Version.

● It has no strap-ons.
● It has a carrying capacity of less than 1000 kg to LEO.

PSLV- DL ● It has two strap-on motors

● It has a payload capacity of 1257kg.

PSLV-QL ● It has four strap-on motors.

PSLV-XL ● It has Six strap-on motors.

● It can carry a payload of up to 1750 kg and 1350 kg to LEO and
GTO respectively.

PSLV-3S ● It is an underdeveloped version of PSLV.

● It will not have any strapons and also will not have second
stage.
● It will be meant for Small satellites and will carry a payload of
upto 500kg to LEO.

2.6.2.3 GSLV: Geosynchronous Satellite Launch Vehicle

● It is an expandable version
● It has three stages:
○ First stage is a solid stage with four liquid strapons motors.
○ Second stage is a Liquid stage (UDMH: Unsymmetrical dimethylhydrazine)
and uses Vikas Engine.
○ Third stage is Cryogenic. CE-7.5 is India’s first cryogenic engine, developed
by the Liquid Propulsion Systems Centre.
● Versions of GSLV
○ GSLV MK-I
■ Third stage of this rocket is made of a Russian cryogenic engine.
■ Rest stages are standard.
■ It has a carrying capacity of 1500 kg to GTO.
■ It has had 6 launches so far and 4 failed.
○ GSLV MK-II:
■ Third stage of this rocket is CE-7.5.
 ■ It has a carrying capacity of 2500 kg to GTO.
■ Ist launch of GSLV MK-II was GSLV D5
■ Its Functional stage is GSLV -F09
○ GSLV MKIII:
■ All 3 stages improved with the first stage carrying two strapons and the
third stage being CE 20.
■ It has a payload carrying capacity of 4 tonnes to GTO and 10 tonnes to
LEO
■ It is also known as BAHUBALI.
■ Its first launch was GSLV D1 for satellite GSAT 19.
■ It is next aimed at taking 6 tonnes of payloads by using the
semi-cryogenic engine in the Second stage.
■ It was used in Chandrayaan and will be used in Mangalyaan 2.

Future Goals of Launch Vehicles

● To develop a reusable launch vehicle.
● To develop Air breathing propulsion system.
● To take Man to space.

2.6.2.4 SSLV
● Small Satellite Launch Vehicle (SSLV) is a three-stage Launch Vehicle.
● It is configured with three Solid Propulsion Stages and a liquid propulsion-based Velocity
Trimming Module (VTM) as a terminal stage.
● It can launch 500kg satellites in a
500km planar orbit from Satish
Dhawan Space Centre (SDSC).
● It provides benefits like Low cost,
Low turn-around time and minimal
launch infrastructure requirements,
etc.
● Significance:
○ The Era of small satellites;
■ With the emergence
of various players like
Businesses,
government agencies,
universities, and
laboratories began to
send satellites and
these satellites mostly
 fall in the category of small satellites
○ Increase Demand:
■ In last decade the demand for the launch of small satellites has increased
at a rapid pace due to the ever-growing need for space-based data,
communication, surveillance, and commerce.
○ Business opportunity:
■ As the rockets could be launched frequently with less cost, this provides a
business opportunity for space agencies like ISRO to tap the potential of
the sector as most of the demand comes from companies that are
launching satellites for commercial purposes.

Advanced technology Vehicle-Tech demonstrator ( ATV-TD)

Need of ATV-TD:
● More than 50% weight of the propellent is oxidiser so
the need is to develop air-breathing propulsion so that
the weight that needs to be carried is reduced
● In August 2016, the first experimental mission of
scramjet engine towards its realisation fo air breathing
was successfully conducted.

ATV-TD
● It is a two-stage sounding rocket.
● It fired the scramjet engine successfully for 5
seconds.

LAUNCHING EXPERIMENTS
● REX: Re-entry experiment: to recover the object
sent for reusable launch vehicle and man to
space mission
● LEX: landing experiment
● HEX: hypersonic flight experiment
○ Brahmos: supersonic (2-5M)
○ Target: Brahmos II to be hypersonic (
5-10 M)
● SPEX: scramjet propulsion experiment

Reusable Launch Vehicle: Technology Demonstrator

(RLV-TD)
 ● It is one of the most technologically challenging endeavours of ISRO towards developing
essential technologies for a fully reusable launch.
● The Configuration of RLV-TD is similar to that of an aircraft and combines the complexity
of both launch vehicles and aircraft.
● The minged RLV-TD is configured to act as a flying testing bed to evaluate various
technologies such as hypersonic flight, autonomous landing and powered cruise flight.
● It will be mounted on PSLV.
● After the payload is delivered, it will enter the earth’s atmosphere.

Need
● It will save cost as the cost for the launch was 5000$/ Kg and if reusable then it will be
500 $/ Kg.
● It will also solve the problem of space debris.

2.6.3 Engines
The engines primarily work on the principle of Newton’s 3rd law of motion i.e. For every action
there is an equal and opposite reaction.
I. Conventional Jet Engine
● In conventional jet engines rotating blades draw in the air and compress it.

● mixture of fuel and air burns and expands in the combustion chamber.
● Hot compressed air and gases are forced out of the exhaust nozzle which in turn
produce thrust.

II. Ramjet engine

● A ramjet engine is a form of an air-breathing jet engine.
 ● It uses the vehicle’s forward motion to compress incoming air for combustion without a
rotating compressor.

● Ramjet engines work most efficiently at supersonic speeds but they are not efficient at
hypersonic speeds.

III. Scramjet Engine

● A scramjet engine is an improvement over the ramjet engine.
● It efficiently operates at hypersonic speeds and allows supersonic combustion.

IV. Cryogenic Engines

● Only Six countries in the world have cryogenic capabilities namely the USA, Russia,
China, France, Japan
and India.
● In these engines
Liquified gases are
stored at very low
temperatures (most
commonly liquid
hydrogen at -253
degrees Celcius) and
are used as fuel and
liquid oxygen (at -183
degrees celsius) as
oxidizers.
● It needs special
insulated containers and
it has vents which allow
gas to escape from the
evaporating liquids.
 ● Working: the fuel expands as it burns and the hot gases are directed out of the nozzle to
provide thrust.

V. Semi-Cryogenic Engines
● It uses refined kerosene instead of liquid hydrogen as in a cryogenic engine.
● Refined kerosene is lighter and can be stored at a normal temperature.
● Oxidiser used is Liquid Oxygen (-153 degrees Celsius).
● It is eco-friendly and cheaper.
● It increases the carrying capacity of the launch vehicles.
● GSLV MK III achieved so far a carrying capacity of 4 tonnes and aims to achieve 6
tonnes.

Propellents:
Parameter for a good Propellents
● Specific impulse: Higher the specific impulse of the propellents lesser the weight of the
propellants.
● Isp= thurst generated/ weight of fuel consumed per seconds
● Increasing order of Isp is SOLID<<<< LIQUID<<<<CRYOGENIC
Solid Fuel:
● It is generally used in first stage
● Fuel is HTPB i.e. Hydroxyl-terminated polybutadiene.
● Oxidizers used with solid fuel are ammonium percolate.
The benefit of Solid Fuel
● It has high thurst values which is required to launch.
● It is relatively cheap
● It has a huge shelf life which is easy to transport
● As it is used in the first stage, the mass is generally at the bottom thus better trajectory
control because of the low centre of gravity.
The negative impact of solid fuel:
● Low Isp thus it increases mass in turn.
● Poor control of combustion and may lead to poor trajectory
Liquid Fuel
● Fuel used is unsymmetrical dimethyl hydrazine (UDMH)/ MMH (monomethyl hydrazine)
● Oxidizers used are dinitrogen tetraoxide(N2O4).
● Vikas engine is an indigenous liquid engine.
The benefit of Liquid Fuel
● Increased Isp thus less mass.
● Good control of combustion.
The negative impact of Liquid fuel:
 ● Slosh: fuel shake will create turbulence and thus will disturb trajectory
● It can lead to Leakage and related explosion
● It is highly corrosive and hence has less shelf life.

Cryogenic fuel
● It uses liquid hydrogen ( -252 deg. cel) which is a big issue to manage.
● Oxidizer used is liquid oxygen ( -153deg. C).
● Leakage is an even bigger problem if occur
● Two variants of the cryogenic indigenous engine include CE 75 which is less powerful
and CE 20 which is more powerful.
Ion Propulsion
● It has a maximum Isp value.
● It works on the principle of Force is equal to mass and acceleration, so there is no
combustion.
● Working: Xe ion when hit by an electron succumbs to the negative grid and hence
releases charge thus causing upward thrust.

● Ion propulsion is not in the launched vehicle as the thurst generated is low, hence it is
used as an auxiliary system for satellites (as satellites do not face atmospheric
resistance, a slight push is sufficient)
● GSAT 7 or the south Asian satellite or SAARC satellite was the first to use ion
propulsion partially.
 HYDRAZINE
● It is a preferred propellant in the space industry as it has a high performance.
● However it comes with various hazards such as environmental and health
hazards.
● It is highly corrosive and its manufacturing, storage, and handling are difficult.

To replace Hydrazine, ISRO is working on HAN (hydroxyl ammonium nitrate/

hydroxylamine nitrate) based propellant.

HAN-based propellants:
● It consists of HAN, ammonium nitrate, methanol and water.
● Methanol was added to reduce combustion instability.
● It can control the burn rate and lower the freezing point of propellant
● It allows safe storage.
● It has the potential to increase density and effective specific impulse by more than
10% as compared to hydrazine.

Previous Year Questions

2018
With reference to India's satellite launch vehicles, consider the following statements:
1. PSLVs launch satellites useful for Earth resources monitoring whereas GSLVs are
designed mainly to launch communication satellites.
2. Satellites launched by PSLV appear to remain permanently fixed in the same position in
the sky, as viewed from a particular location on Earth.
3. GSLV Mk III is a four-stage launch vehicle with the first and third stages using solid
rocket motors, and the second and fourth stages using liquid rocket engines.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3
(c) 1 and 2
(d) 3 only

Answer: A
2.7. Space station

Space station is an artificial structure placed in orbit which has the pressurized
enclosure, power, supplies, and environmental systems necessary to support human habitation
for extended periods. A space station can serve as a base for a variety of activities such as
observations of the Sun and other astronomical objects, study of Earth’s resources and
environment, military reconnaissance, and long-term investigations of the behaviour of materials
and biological systems.

2.7.1 International Space Station

The International Space Station (ISS) is a space station in low earth orbit. It is a manmade
space station or an artificial satellite that is habitable for humans in space. There are astronauts
living onboard the space station
conducting experiments on earth
science, biology, biotechnology,
astronomy, microgravity,
meteorology, physics, etc.

About ISS
● The ISS was launched in
1998.
● The first crew reached the
ISS in 2000. Since then it
has always been manned
by astronauts.
● It was developed and built
by five space agencies
namely, NASA (USA),
Roscosmos (Russia),
European Space Agency
 (ESA-Europe), JAXA (Japan) and the Canadian Space Agency (CSA-Canada).
● It is at an altitude between about 200 km and 400 km and weighs more than 400,000 kg.
● Astronauts conduct spacewalks (that is, stepping out of the ISS onto space) and there
have been over 200 spacewalks until now.

ISS Program Evolution

● The first Station which was conceived in 1984 by NASA was the Space Station Freedom
However, it was never constructed as per the original design..
● Russian space station Mir-2 started in 1976 and some of the modules built for it have
been incorporated into the ISS.
● The ISS was the ninth crewed space station, the other earlier ones being Salyut, Almaz,
and Mir stations of Russia and Skylab of the US.

Latest News w.r.t ISS

● Russia announced its exit in 2025.
● Russia was a vital component of the ISS with countries depending on its modular
space station construction technology to build the station in the early years.
● Russia’s Soyuz passenger vehicle that transported people to the ISS ever since
2011 when the US retired its space shuttle program.
● Russia is also planning to build its own space station, expected to be launched
into orbit by 2030.

2.7.2 China’s Space station

● Chinese space station is the Tiangong space station.
● It is a being built in low Earth orbit between 340 and 450 kilometers above the earth.
● It is also a part of China Manned Space Program. It is the country's first long-term space
station.
● It will be operational for at least ten years.
● China launched an unmanned module named "Tianhe", or "Harmony of the Heavens"
for its permanent space station in 2021 that it plans to complete by the end of 2022.
● Tianhe core module is the first module to launch the Tiangong space station module.
● Modules Shenzhou-1 to 4 were unmanned spaceflight missions and Shenzhou-5 to 14
spaceflights are manned spaceflight missions.

2.7.3 India's Space Station Programme

India is planning to launch its own space station by 2030 and will join the league of US,
Russia, and China to an elite space club.
About the proposed space station:
● It will be much smaller (mass of 20 tonnes) than the International Space Station.
● It will be used for carrying out microgravity experiments (not for space tourism).
● Preliminary plan for the space station is to accommodate astronauts for up to 20 days
in space. This project will be an extension of the Gaganyaan mission.
 ● It will orbit Earth at an altitude of around 400 km.
● ISRO is also working on a space docking experiment called Spandex.
● Space docking is a technology which allows for transferring humans from one
spacecraft to another.

2.8. Positioning System

2.8.1 GPS
Global Positioning System or GPS is a satellite-based navigation system developed by
the U.S. Department of Defense (DOD) in the early 1970s. Initially, GPS was developed
for military purpose and later was made available to civilians.

About GPS:
● The first satellite under GPS was launched in 1978.
● Complete constellation of 24 satellites was achieved in 1994.
● Satellites under GPS are arranged so that four satellites are placed in each of six
orbital planes so that, four to ten GPS satellites are visible anywhere in the world.

GPS NavIC
It is a global positioning system It is a regional positioning System
It has a constellation of 24 operational It has 7 in orbit satellites
sattelite
It functions in L1 and L2 band It functions in L5 band and S band
Atomic clock used ismde up of cesium Atomic clock is a swiss clock made up of Rubdium.
Resolution of GPS satellites is 5 m Resolution of NavIC is 17-20 metres

2.8.2 NavIC
About NavIC
● NavIC stands for Navigation in Indian Constellation.
● NavIC is Indian Regional Navigation satellite or IRNSS.
● Initially Seven satellites were launched and two were in standby.
● It covers 32 degrees East and 130 degrees East.
● All the satellites were laced in geosynchronous orbit out of which three were in
geostationary orbt namely 1C, 1D, 1G.
● In IRNSS 1A atomic lcock has become disfunctional and to replace this,IRNSS 1H was
launched in PSLV c-39 launch vehicle
○ This was the first satellite built by private firm.
 ○ But mission failed as the launch vehicle’s payload fairing failed to open.
● The first satellite (IRNSS-1A) was launched on 1st July 2013 and the eighth satellite
IRNSS-1I was launched in April 2018

Uses
● Disaster management
● Terrestrial, aerial and marine navigation;
● Vehicle tracking and fleet management (especially for mining and transportation sector)
● Integration with mobile phones
● Mapping and geodetic data capture.
● Precise timing (as for ATMs and power grids)

Services that will be provided by NavIC

● SPS: standard positioning service which will be there for civilian use.
● RS: Restricted Service which will be for military use.
Significance
● India became one of the only 5 countries having their own navigation system this will
decrease India's dependence on other countries for navigation purposes.
● It will help in scientific & technological advancement for India and thus is important for
the country’s sovereignty and strategic requirements.
● In April 2019, the government made NavIC-based vehicle trackers mandatory for all
commercial vehicles in the country.
● one of the stated future uses of the project includes sharing of the project with the
SAARC nations.

Previous Year Questions

2018
With reference to the Indian Regional Navigation Satellite System (IRNSS), consider the
following statements:
1. IRNSS has three satellites in geostationary and four satellites in geosynchronous orbits.
2. IRNSS covers entire India and about 5500 sq. km beyond its borders.
3. India will have its own satellite navigation system with full global coverage by the middle
of 2019.
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) None

Answer: A
2.9 Issues in Space technology

Privatisation in the Space sector in India

The participation of Private players in Space in India is on small scale for a long time.
They are involved in the manufacturing and fabrication of rockets and satellites happens in the
private sector. Also, participation in research institutions is increasing.

Space Industry
● However, the Indian industry had only a 3% share in a rapidly growing global space
economy which is worth at least $360 billion.
● Only 2% of this market is for rocket and satellite launch services as it requires a fairly
large infrastructure and heavy investment.
● Remaining 95% market is related to satellite-based services, and ground-based
systems.
Reason for Less participation of India
● Indian industry is unable to compete as its role till now has been mainly that of suppliers
of components and sub-systems.
● Indian industries lack the resources or the technology to undertake independent
space projects of the kind that US companies such as SpaceX have been doing or
provide space-based services.
● ISRO is unable to cater to the demand for space-based applications and services which
is growing even within India.
● The need for satellite data, imageries, and space technology now extend across sectors,
from weather to agriculture to transport to urban development and more.
● There is a need for greater dispersion of space technologies and better utilization of
space resources. There is also an increased requirement for space-based services.

Various steps are taken to facilitate private participation

Due to this ever-increasing need and demand, ISRO is facilitating the participation of Private
players in space development with the projects like IN-SPACe.
● IN-SPACE
○ It was launched to provide a level playing field for private companies to use
Indian space infrastructure.
○ It will act as a single-point interface between Indian Space Research
Organisation (ISRO), and everyone who wants to participate in space-related
activities or use India’s space resources.
● NewSpace India Limited (NSIL)
 ○ It was announced in Budget 2019, its mandate is to use research and
development carried out by ISRO over the years for commercial purposes
through Indian industry partners.
● Indian Space Association (ISpA):
○ It aspires to be the collective voice of the Indian Space industry.
○ It will be represented by leading domestic and global corporations who have
advanced capabilities in space and satellite technologies
● Private companies are allowed to build their launchpad within the Sriharikota launch
station, and ISRO will provide the necessary land for the purpose.
● Also, the Minister of State for the Department of Space (DOS) informed the Lok
Sabha that the government was looking for opening the space sector to Foreign
Direct Investment which in turn will benefit ISRO by
○ allowing ISRO to focus more on Research and development.
○ It will aid in developing the Indian space industry into a global technology
powerhouse.

Need of Reforms in the Space sector

● To increase the scale of the sector as ISRO is centrally funded and its annual budget
is between Rs 14-15,000 crore, which is less in order for India to witness exceptional
growth in the sector and is a majorly used for building rockets rather than in
innovation.
● ISRO is also planning to share knowledge and technology, such as manufacturing
rockets and satellites with all the private players.
● Various developed countries like the United States, Europe, and Russia all have
space industries with big players like Boeing, SpaceX, Air Bus, Virgin Galactic, etc.
● Private players can bring in the innovation which is needed for developing
space-based applications and services.
● Further, the demand for these services is soaring worldwide and in India, with satellite
data, imageries and space technology being used across most sectors.
● The Private players can participate in setting up ground stations for space crafts
which constitute 48% of the space sector budget. They can also help in the
application of space technology which results in 45% of the space economy.

Space Weaponisation

Definition: Space weaponization is the process of placement of weapons in outer space .

Space Weaponisation involves the creation of weapons that will transit outer space or simply
travel from earth to attack or destroy targets in space.

The weaponization of space V/S militarization of space

● Militarization of space includes the usage of space-based assets for command,
control, communication, surveillance, and reconnaissance activities.
 ● Militarization of space assists armies on the conventional battlefield whereas in
weaponization of space, outer space itself becomes the battlefield and Space
emerges as the ‘fourth frontier of war’.
● Examples of space weaponization are placement of orbital or suborbital satellites
with the intention of attacking enemy satellites, the use of ground-based direct
ascent missiles to shoot space jets, jamming signals sent from enemy satellites,
etc.

Why space weaponization?

● The desire to establish military supremacy on all fronts of warfare.
● Lack of faith in the present missile defense system to stall an Intercontinental Ballistic
Missile.
● Space Weaponisation is to preserve space assets from incoming anti-satellite weapons
(ASAT).
● Space supremacy also complements other areas of warfare like sea, air, and land.

Impacts of Space Weaponization

● Space weaponization leads to mutual suspicion and generates fear of war generates
competition and aggressive deployment between nations.
● It is a Threat to other commercial and scientific missions A country that deploys a
military satellite would be reluctant to disclose sensitive information like orbital and radio
frequency. This affects the entire coordination system
● Space weaponization can further increase the concern of an increase in space debris.
● There are limited number of orbital slots gets monopolized by developed countries
limiting the scope for scientific and commercial explorations.

Global Frameworks to Prevent Space Weaponization

● Outer Space Treaty which was conceptualized by the United Nations in 1967
emphasised that the use of outer space should be peaceful and beneficial to all
mankind. It also ensures that one nation cannot claim national sovereignty in outer
space.
● Prevention of an outer space arms race-It stresses the use of space for peaceful
purposes. Further, it calls for the importance of avoiding an arms race.

Space Debris
Space debris consist of spent rocket stages, dead satellites, fragments of space objects and
junk resulting from Anti-satellite System (ASAT).
About Space Debris:
● It poses a global threat to the continued use of space-based technologies which support
critical functions like communication, transport, weather and climate monitoring, remote
sensing.
● This free floating debris has a potential hazard for operational satellites. It can collide
with them can leave the satellites dysfunctional.

Kessler Syndrome
It is named after National Aeronautics and Space Administration (NASA) scientist Donald
Kessler in 1978. This syndrome says if there is too much space junk in orbit, it could
result in a chain reaction where more and more objects will collide and create new space
junk in the process, to the point where Earth's orbit becomes unusable. (Domino Effect)

Amount of space debris

● It is said to be between 500,000 and one million pieces as current sensor technology
cannot detect smaller objects.
● Space Debris travel at speeds of up to 17,500 mph (28,162 kmph) fast enough for a
relatively small piece of orbital debris to damage a satellite or a spacecraft.

Various Projects to counter Space debris:

● Project Netra
○ NETRA stands for Network for Space Objects Tracking and Analysis (NETRA)
project.
○ ISRO had set up a dedicated Space Situational Awareness (SSA) Control
Centre named “Netra” in Bengaluru.
○ It is mandated to safeguard space assets from space debris.
○ The key objective of Netra is to monitor, track and protect the national space
assets and function as a hub of all SSA activities.
○ The US, Russia and Europe are the only countries which have similar facilities in
place to track space objects and share collision warnings.
○ It was needed as for protecting its space assets, the ISRO was forced to perform
19 Collision Avoidance Manoeuvres (CAM) in 2021.
○ Under NETRA, the ISRO plans to put up many observational facilities such as
connected radars, telescopes, data processing units and a control centre.
● India’s Anti-Satellite (ASAT) missile
○ ASAT or Mission Shakti is a joint programme of the Defence Research and
Development Organisation (DRDO) and the Indian Space Research Organisation
(ISRO).
○ Under shakti mission, an anti-satellite (A-SAT) weapon was launched and
targeted an Indian satellite which had been decommissioned.
○ It was carried out from DRDO’s testing range in Odisha’s Balasore.
○ Significance
■ India is only the 4th country after US, Russia and China to acquire such a
specialised and modern capability, and Entire effort is indigenous