Awareness in fields of Space

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• The Big Bang Theory is the prevailing cosmological model for the birth of the universe.
• It states that at some moment all of space was contained in a single point of very high-density and high-temperature state from which the universe has been expanding in all directions ever since.
• Modern measurements place this moment at approximately 13.8 billion years ago.
• After the initial expansion (inflation), the universe cooled sufficiently to allow the formation of subatomic particles and later simple atoms.
• The majority of atoms produced by the Big Bang were hydrogen and helium along with trace amounts of lithium and beryllium.
• Giant clouds of these primordial elements (hydrogen and helium) later coalesced through gravity to form stars and galaxies.
• According to this theory, the universe, ever since its birth, is expanding in all directions.

• At some point in time, the universe would reach a maximum size and then begin to collapse.
• It would become denser and hotter again, ending with a state similar to that in which it started — a Big Crunch, the death of the universe.

• Redshift and Blueshift describe how light changes as objects in space (such as stars or galaxies) move closer or farther away from us. The concept is key to charting the universe’s expansion.
• Visible light is a spectrum of colours, which is clear to anyone who has looked at a rainbow.
• When an object moves away from us (Doppler-shifted to lower frequencies), the light is shifted to the red end of the spectrum, as its wavelengths get longer.
• If an object moves closer (Doppler-shifted to higher frequencies), the light moves to the blue end of the spectrum, as its wavelength gets shorter.
• American astronomer Edwin Hubble was the first to describe the redshift phenomenon (galactic redshift) and tie it to an expanding universe (galaxies are drifting apart).
• Hubble’s law: the farther away galaxies are, the faster they are moving away from Earth ― also known as accelerating the expansion of the universe.

• With a traditional optical telescope, the space between stars and galaxies is completely dark.
• However, a sensitive radio telescope shows a faint background glow. This glow is strongest in the microwave region of the radio spectrum, and hence it is called a cosmic microwave background.

• Dark energy is an unknown form of energy that is hypothesized to permeate (spread throughout) all of space, tending to accelerate the expansion of the universe.

• Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe. Dark energy plus dark matter constitutes 95% of the total content of the universe.
• It is believed that dark matter considered as the factor for the unexplained motion of stars in galaxies.
• The majority of dark matter is thought to be composed of some as-yet-undiscovered subatomic particles.
• Dark matter does not appear to interact with observable electromagnetic radiation, such as light, thus invisible to the entire electromagnetic spectrum, making it extremely difficult to detect.
• Dark matter interacts with the rest of the universe only through its gravity.

• It is hypothesized that every elementary particle in the Universe has a partner particle, known as an ‘antiparticle’.
• The particle and its antiparticle share many similar characteristics, but many other properties are the exact opposite.
• The electron, for example, has as its antiparticle the antielectron. They both have the same masses, but they have exactly opposite electrical charges.
• Most of the human understanding of the antimatter comes from high energy accelerator experiments.
• When a matter particle meets its antimatter particle, they destroy each other completely (i.e. annihilation), releasing the energy equivalent of their rest masses (following Einstein’s E = mc2).
• For instance, when an electron meets an antielectron, the two annihilate and produce a burst of light which produces a corresponding energy level equivalent to the masses of the two particles.

• Higgs Boson or God particle is theoretically responsible for mass, without which there would be no gravity and no universe. So, called as “God particle”.
• The Higgs particle was proposed in the 1960s by British physicist Peter Higgs as a way of explaining why other particles have mass.
• The Discovery of Higgs Boson validated the Standard Model of physics, also predicted that 60% of the time a Higgs boson will decay to a pair of bottom quarks.
• Standard Model: It is a theory of particle physics. It says materials are made up of 12 matter particles(known as Fermions). The other 11 particles predicted in models have been found. CERN used the Large Hadron Collider(LHC) to find God particles.

• The LHC is the world’s largest and most powerful particle accelerator.
• It consists of a 27-kilometre ring of superconducting magnets with many accelerating structures to boost the energy of the particles along the way.
• LHC started operation in 2008, it is a Global collaboration project led by CERN (the European Organization for Nuclear Research). Its first research took place in March 2010&discovered the elusive (difficult to find, catch, or achieve) Higgs Boson in July 2012.
• The LHC is situated underneath the earth’s surface at a depth of 175 metres on the border between France and Switzerland near Geneva.
• Purpose: LHC was built to study some of the fundamental particles (like proton, Higgs Boson etc.,) and how they interact and behaved as well as to find answers to other unsolved questions of physics like dark matter.

• About:
  • Neutrinos are the second most widely occurring particle in the universe, only second to photons, the particle which makes up light.
  • These were first proposed by Swiss scientist Wolfgang Pauli in 1930.
• Characteristics:
  • They are elementary weakly interacting subatomic
  • They have little mass or are nearly massless.
  • They are no-charge particles that only interact with weak nuclear force.
  • Least harmful of all elementary particles, as they seldom react with solid bodies.
  • Gave astronomical information like beta decay of star or supernova.
  • In 2015, the Nobel Prize in physics was awarded to Takaaki Kajita and Arthur B. Mcdonald for discovering neutrino oscillations demonstrating that neutrinos have mass.
  • There are three types of neutrino namely, electron neutrino (Ve), Muon neutrino (Vμ)&Tau neutrino (Vτ).

• INO is a multi-institutional effort aimed at building a world-class underground laboratory with a rock cover of approximately 1200 m for Non-accelerator based high energy and nuclear physics research in India. It is situated at Theni (Tamil Nadu ).
• It is a mega-science project jointly funded by the Department of Atomic Energy (DAE) and the Department of Science and Technology (DST).
• The initial goal of INO is to study Neutrinos.

• Neutrinos hold the key to important and fundamental questions on the origin of the Universe and the energy production in stars.
• For Neutrino tomography of the earth, that is a detailed investigation of the structure of the Earth from core onwards. This is possible with neutrinos since they are the only particles that can probe the deep interiors of the Earth.

The INO project includes:

• Construction of an underground laboratory and associated surface facilities at Pottipuram in Bodi hills of Theni District of Tamil Nadu.
• Construction of an Iron Calorimeter (ICAL) detector for studying neutrinos.
• Setting up of National Centre for High Energy Physics at Madurai, for the operation and maintenance of the underground laboratory.
• Note: Japan is planning to build a Hyper-Kamiokande neutrino detector which will be the world’s largest neutrino observatory.

• Formation:
  • Stars are formed in clouds of gas and dust, known as nebulae. Nuclear reactions(fusion- hydrogen to helium) at the centre (or core) of stars provides enough energy to make them shine brightly for many years.
• Lifetime:
  • The exact lifetime of a star depends very much on its size. Very large, massive stars burn their fuel much faster than smaller stars and may only last a few hundred thousand years. Smaller stars, however, will last for several billion years, because they burn their fuel much more slowly.
• Phases:
  • When hydrogen fuel that powers the nuclear reactions within stars will begin to run out, they enter into the final phases of their lifetime. Over time, they will expand, cool and change color to become red giants. The path they follow beyond that depends on the mass of the star.
• Small stars:
  • Like the Sun, will undergo a relatively peaceful and beautiful death that sees them pass through a planetary nebula phase to become a white dwarf, which eventually cools down over time and stops glowing to become a so-called “black dwarf” which emits no energy.
• Massive stars:
  • It will experience a most energetic and violent end, which will see their remains scattered about the cosmos in an enormous explosion, called a supernova. Once the dust clears, the only thing remaining will be a very dense star known as a neutron star, these can often be rapidly spinning and are known as pulsars. If the star which explodes is especially large, it can even form a black hole.
• Chandrasekhar Limit:
  • It is of 1.4 solar masses, is the theoretical maximum mass a white dwarf star can have and still remain a white dwarf. Above this mass, electron degeneracy pressure is not enough to prevent gravity from collapsing the star further into a neutron star or black hole.
  • The limit is named after Nobel laureate Subrahmanyan Chandrasekhar, who first proposed the idea in 1931.

• A black hole is an object in space that is formed after the death of a star(core runs out of fuel) and is so dense and has strong gravity that no matter or light can escape its gravitational pull. Because no light can escape, it is black and invisible.
• Types of Black holes:
  • Steller-mass black holes:
    • Small black holes have masses about five to 20 times the mass of the sun.
  • Super-massive black holes:
    • Which are millions to billions of times more massive than the sun.
    • Super-massive black holes are found at the centre of most galaxies. The super-massive black hole in our own galaxy, Milky Way is called Sagittarius A*.

• The boundary at the edge of a black hole is called the event horizon. This is a “point of no return”, beyond which it is impossible to escape the gravitational effects of the black hole.
• Anything that crosses the event horizon, falls to the very centre of the black hole and squished into a single point with infinite density, called the

• EHT is a group of 8 radio telescopes used to detect radio waves from space.
• In 2019, Scientists from the EHT project released the first-ever optical image( or shadow image) of a Blackhole located in the center of galaxy Messier 87 in the constellation Virgo.
• Sagittarius A* is the 2nd black hole to get photographed.
• Nobel Prize in Physics, 2020 – “for the discovery that black hole is a robust prediction of the general theory of relativity” to Roger Penrose and “ for the discovery of supermassive compact object at the centre of our galaxy” to Reinhard Genzel and Andrea Ghez.

• Gravitational waves are the distortions or ‘ripples in the fabric of space-time.
• Gravitational waves are produced when objects accelerate and travel with the speed of light.
• The strongest gravitational waves are produced by catastrophic events such as on merger of black holes, the collapse of stellar cores(supernovae), coalescing neutron stars or white dwarfs.
• Gravitational waves were first proposed by Albert Einstein, 100 years ago as part of the Theory of Relativity.
• In 2016, scientists at Laser Interferometer Gravitational-wave Observatory (LIGO) first detected the gravitational waves.
• Nobel prize in Physics, 2017 – “for decisive contributions to LIGO detector and the observation of gravitational waves” to Rainer Weiss, Barry Barish and Kip Thorne.
• The gravitational waves can work as sirens to measure the expansion rate of the universe and to understand the origin and the future of the universe.

Hubble’s Law: the farther away galaxies are, the faster they are moving away from Earth ― accelerating expansion of the universe).

Hubble constant: A unit of measurement that describes the rate at which the universe is expanding.

• World largest gravitational wave observatory for detecting cosmic gravitational waves and for carrying out experiments.
• Comprises of two enormous laser interferometers located thousands of kilometres apart, each having two L-shaped arms of 4km in length.
• Two LIGO detectors are already operational in the U.S, at Livingston and Hanford.
• The Japanese detector, KAGRA recently joined the international network.

• LIGO-India project is the Indian Initiative in Gravitational-wave observations, expected to be completed by 2025.
• aims to move one Advanced LIGO detector from Hanford to Maharashtra(Hingoli district), India.
• Project is piloted by dept. of Atomic Energy(DAE) and dept. of Science and Tech(DST).
• This project will help Indian scientists to be a major player in the emerging research frontier of GW astronomy.

KUIPER BELT: The Kuiper Belt is a ring of icy rocks & dust bodies just outside of Neptune’s orbit, known as Kuiper belt objects or Pluto is the largest known Kuiper Belt Object instead of the 9th planet of our Solar system. There are bits of rock and ice, comets, and dwarf planets.

PLOONET: A celestial object, which are orphaned moons that have escaped the bonds of their planetary parents. The researchers explain that the angular momentum between the planet and its moon results in the moon escaping the gravitational pull of its parent planet. A new study finds that Earth’s own Moon is slowly spiralling away from the planet; it may also end up as a ploonet in some 5 billion years.

EXOPLANET: Planets orbiting the other stars(outside our solar system) are called “exoplanets.” Exoplanets are hard to see, they are hidden by the bright glare of the stars they orbit. Scientists use Gravitational lensing and the “wobbling methods” to detect exoplanets. Proxima Centauri b is the closest exoplanet to earth and inhabits the “habitable zone” of its star. Gravitational lensing: Light around a massive object, such as a black hole, is bent, causing it to act as a lens for the things that lie behind it.

GOLDILOCKS ZONE: The ‘Goldilocks Zone,’ or habitable zone – ‘the region around the star where a planet could sustain liquid water on its surface. Our Earth is in the Sun’s Goldilocks zone. If Earth were where the dwarf planet Pluto is, all its water would freeze; on the other hand, if Earth were where Mercury is, all its water would boil off. Some Earth-size planets like TOI 700 d and Kepler-186f have been discovered in their Goldilocks zone.

Asteroids: Big chunks of rocks floats through space and orbit the sun, mostly found in the main asteroid belt i.e. between Mars and Jupiter. The biggest one is Ceres(940km wide), as twice as big as Grand Canyon.

Meteoroid, Meteor and Meteorite:

Meteoroid: Smaller rock pieces that break off from asteroid, it floats through interplanetary space. Can be as small as a grain of sand or as large as a metre across.

Meteor: When a meteoroid enters the earth atmosphere, it begins to burn up and fall to the ground. This burning trail is known as a meteor or ‘falling stars. Meteors and comets both create bright trails through the night, but comets are made up of ice and dust, not rock – like a giant dirty snowball.

Meteorite: If a meteoroid rock doesn’t completely burn up as it falls to Earth– the rock left behind is called a meteorite.

• Kepler’s First Law:
  • The orbit of a planet is an ellipse with the Sun at one of the two foci.
• Kepler’s Second Law:
  • A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
  • In simple words, the speed of the planet increases as it nears the sun and decreases as it recedes from the sun.
• Kepler’s Third Law:
  • The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

• On basis of height:
  • LEO Satellite (Lower Earth Orbit)
  • MEO Satellite (Middle Earth Orbit)
  • Highly Elliptical Orbit (HEO)
• On basis of application:
  • Geo- Synchronous Earth Orbit
  • Geo- Stationary Earth Orbit

Low Earth Orbit (LEO)

• LEO is commonly used for communication and remote sensing satellite systems, as well as the International Space Station (400km) and Hubble Space Telescope (560km).
• The satellites in LEO complete multiple revolutions in 24 hours (Lower the orbit, higher should be the speed).

Medium Earth Orbit

• MEO is commonly used for navigation systems, including the U.S. Global Positioning System (GPS).

Highly Elliptical Orbit (HEO)

• An HEO is oblong, with one end nearer the Earth and the other more distant. Satellites in HEO are suited for communications, satellite radio, remote sensing and other applications.

• Advantages:
  • Low Earth Orbit is used for things that we want to visit often, like the International Space Station, the Hubble Space Telescope and some satellites (usually spy satellites and other observation satellites).
  • This is convenient for installing new instruments, experiments, and return to earth in a relatively short time.
• Disadvantages of LEO:
  • Atmospheric drag will lead to more fuel consumption and constant speed adjustments.
  • A satellite travelling in LEO do not spend very long over any one part of the Earth at a given time.
  • Hence, satellites in LEO are not suitable for communication and weather observation and forecasting.
• Solution:
  • One solution is to put a satellite in a highly elliptical orbit (eccentric orbit ― non-geosynchronous).
  • The other is to place the satellite in a geosynchronous orbit.

Geosynchronous Orbits (GSO)

• Another solution to the dwell time problem is to have a satellite whose orbital period is equal to the period of rotation of the earth (24 hrs) (satellite’s revolution is in sync with the earth’s rotation).
• In this case, the satellite cannot be too close to the Earth because it would not be going fast enough to counteract the pull of gravity.
• Using Kepler’s third law it is determined that the satellite has to be placed approximately 36,000 km away from the surface of the Earth (~42,000 km from the centre of the Earth) in order to remain in a GSO orbit.
• By positioning a satellite so that it has infinite dwell time over one spot on the Earth, we can constantly monitor the weather in one location, provide reliable telecommunications service, etc.
• The downside of a GSO is that it is more expensive to put and maintain something that high up.

Geostationary Orbit or Geosynchronous Equatorial Orbit (GEO)

• A geostationary orbit or geosynchronous equatorial orbit is a circular geosynchronous orbit above Earth’s equator and following the direction of Earth’s rotation.
• Because the satellite stays right over the same spot all the time, this kind of orbit is called “geostationary.”

• Polar Orbits (PO)
  • Satellites in these orbits fly over the Earth from pole to pole in an orbit perpendicular to the equatorial plane.
  • This orbit is used in surface mapping and observation satellites since it allows the orbiting satellite to take advantage of the earth’s rotation below to observe the entire surface of the Earth as it passes below.
  • Pictures of the Earth’s surface in applications such as Google Earth come from satellites in polar orbits.
• Sun-synchronous orbits (SSO)
  • Polar orbit and sun-synchronous orbits are low earth orbits.
  • Sun-synchronous orbit is a near-polar orbit in which the satellite passes over any given point of the planet’s surface at the same local mean solar time.
  • When a satellite has a sun-synchronous orbit, it means that the satellite has a constant sun illumination.
  • Because of the consistent lighting, the satellites in sun-synchronous orbit are used for remote sensing applications (image the Earth’s surface in visible or infrared wavelengths) like imaging, spying, etc.

LAUNCH VEHICLE TECHNOLOGY:

• Launchers or Launch Vehicles are used to carry spacecraft to space.
• Historic launchers: SLV, Augmented Satellite Launch Vehicle (ASLV)
• India has two operational launchers: Polar Satellite Launch Vehicle (PSLV) and Geosynchronous Satellite Launch Vehicle (GSLV).
• GSLV with indigenous Cryogenic Upper Stage has enabled the launching up to 2 tons class of communication satellites.
• The next variant of GSLV is GSLV Mk III, with indigenous high thrust cryogenic engine and stage, having the capability of launching 4 tons class of communication satellites.
• Vikram Sarabhai Space Centre, located in Thiruvananthapuram, is responsible for the design and development of launch vehicles.
• Liquid Propulsion Systems Centre and ISRO Propulsion Complex, located at Valiamala and Mahendragiri respectively, develop the liquid and cryogenic stages for these launch vehicles.
• Satish Dhawan Space Centre, SHAR, is the spaceport of India and is responsible for the integration of launchers. It houses two operational launch pads from where all GSLV and PSLV flights take place.

SATELLITE LAUNCH VEHICLE-3 (SLV-3):

• SLV-3was India’s first experimental satellite launch vehicle.
• Which was an all solid, four-stage vehicle
• Capable of placing 40 kg payloads in Low Earth Orbit (LEO).
• First successful launch: Rohini Satellite on 18/July/1980 from Sriharikota.
• This made India the sixth member of an exclusive club of space-faring nation’s.

AUGMENTED SATELLITE LAUNCH VEHICLE (ASLV):

• Designed to augment the payload capacity to 150 kg, thrice that of SLV-3, for Low Earth Orbits (LEO) in 1987.
• ASLV proved to be a low-cost intermediate vehicle to demonstrate and validate critical technologies.

Polar Satellite Launch Vehicle (PSLV):

• An expendable launch system used only once to carry a payload into space. E.g. PSLV, GSLV, etc.
• A reusable launch system is intended to allow for the recovery of the system for later reuse. E.g. NASA’s space shuttles, SpaceX Falcon 9 rocket (reusable first stage and expendable second stage), etc.
• PSLV was developed in the 1990s by ISRO to place satellites (mostly remote sensing satellites) in polar and near-polar (e.g. sun-synchronous orbit) Lower Earth Orbits.
• However, over the last decade, several PSLV missions were successful in sending satellites towards geosynchronous transfer orbit.
• E.g. Chandrayaan-1 – 2008 and Mars Orbiter Mission or Mangalyaan – 2014 were launched using PSLV.
• PSLV can fly in different configurations depending on the mass of its payload and the target orbit.
• These configurations vary the number and type of solid rocket boosters attached to the rocket’s first stage, while the four core stages remain the same across all configurations.
• PSLV’s first stage and third stage are solid-fuelled stages.
• PSLV’s second stage and fourth stage are liquid-fuelled stages.
• The second stage engine, Vikas, is a derivative of France’s Viking engine.
• The PSLV-C (PSLV Core Alone) version of the rocket does not use additional boosters, while the PSLV-DL, PSLV-QL and PSLV-XL use two, four and six boosters respectively.

The Workhorse of India’s space program:

• PSLV earned its title ‘the Workhorse of ISRO’ through consistently delivering various satellites to Low Earth Orbits, particularly the IRS (Indian Remote Sensing) series of satellites.
• PSLV Payload Capacity to SSO: 1,750 kg
• PSLV Payload Capacity to Sub-GTO: 1,425 kg
• In forty-seven launches to date, PSLV has achieved success forty-four times.
• Despite the failure of its maiden flight, PSLV went on to record thirty-six consecutive successful launches from 1999 to 2017.
• PSLVs were used to place the IRNSS satellite constellation (3 in GEO and 4 in GSO) in orbit.

Geosynchronous Satellite Launch Vehicle (GSLV):

• GSLV is also an expendable launch system.
• The GSLV project was initiated to launch geosynchronous satellites (most of them are heavy for PSLV).
• GSLV uses a solid rocket booster and the liquid-fueled Vikas engine, similar to those in PSLV.
• GSLV has a solid-fuelled first stage, liquid-fueled second stage and a cryogenic third stage.
• A Cryogenic rocket stage is more efficient and provides more thrust.
• However, the cryogenic stage is technically a very complex system due to its use of propellants (liquid oxygen ― minus 183 °C and liquid hydrogen ― minus 253 °C) at extremely low temperatures.
• India had to develop cryogenic technology indigenously as the US objected to Russia’s involvement citing Missile Technology Control Regime (MTCR) May 1992.
• A new agreement was signed with Russia for cryogenic stages with no technology transfer.
• GSLV rockets using the Russian Cryogenic Stage (CS) are designated as the GSLV Mk I.
• GSLV rockets using the indigenous Cryogenic Upper Stage (CUS) are designated the GSLV Mk II.
• GSLV Payload Capacity to LEO: 5,000 kg
• GSLV Payload Capacity to GTO: 2,500 kg
• GSLV’s primary payloads are heavy communication satellites of INSAT class (about 2,500 kg) that operate from Geostationary orbits (36000 km) and hence are placed in Geosynchronous Transfer Orbits by GSLV.
• The satellite in GTO is further raised to its final destination by firing its in-built onboard engines.

GSLV Mk II:

• This is the largest launch vehicle developed by India, which is currently in operation.
• This fourth-generation launch vehicle is a three-stage vehicle with four liquid strap-ons.
• The indigenously developed Cryogenic Upper Stage (CUS) forms the third stage of GSLV Mk II.
• Liftoff mass: 4.14 tones.

Geosynchronous Satellite Launch Vehicle Mark III (GSLV-III)

• GSLV-III is designed to launch satellites into geostationary orbit and is intended as a launch vehicle for crewed missions under the Indian Human Spaceflight Programme.
• The GSLV-III has a higher payload capacity than GSLV.
• GSLV-III Payload Capacity to LEO: 8,000 kg
• GSLV-III Payload Capacity to GTO: 4000 kg

*** This is a very open-ended and evolving topic, we have provided an exhaustive blueprint with static coverage from which every question can be handled in this post:

IMPORTANT SPACE MISSIONS(CLICK HERE)

but keep checking the https://samajho.com/tag/science-technology/ and Magazines for future updates.***

*** This is a very open-ended and evolving topic, we have provided an exhaustive blueprint with static coverage from which every question can be handled in this post:

MAJOR TELESCOPES AND THEIR OBSERVATIONS(CLICK HERE)

but keep checking the https://samajho.com/tag/science-technology/ and Magazines for future updates.***