The Universe & The Science : Decoding

The Universe & The Science

I look up at the night sky and wonder about the Universe that we are a part of, I have too many questions!

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Showing posts with label Decoding. Show all posts
Showing posts with label Decoding. Show all posts

Monday, December 21, 2020

CME: A Threat as Devastating as Asteroids

December 21, 2020 0

The Sun is a Giant Bright celestial object of intense nuclear energy. It unleashes billions of tonnes of electromagnetically charged plasma hurtling into space causing what we know as 'solar storms'.

Coronal Mass Ejections (CMEs)

It is a phenomenon in which a large amount of magnetized plasma is released into space from the surface of the Sun. The matter which shoots off into space largely consists of electrons and protons with an average mass of 1.6 x 1012 kg with up to a speed of 3200 km/s as observed by Solar and Heliospheric Observatory(SOHO). At these speeds, These ejections take several days to travel to earth. But the fastest ever recorded was in 1859 during what we refer to as the ‘Carrington Event’. 


What Causes CMEs?

Plasma on the surface of the Sun is an extremely good conductor of electricity and is highly affected by magnetism. The sunspots on the surface of the Sun are the regions where the magnetic fields get tangled. The Size of the sunspots can be anywhere between 15 km to 160000 km(multiple Earths can fit into it). Such enormous changes and disturbances in the magnetic field result in ‘Magnetic Reconnection’. Which converts magnetic energy into Kinetic energy, Thermal energy, and accelerates particles into space. 

How do we see it?

The Sun is the brightest object in our skies, and observing the surface of such a bright celestial body isn’t possible without special equipment. ‘Coronagraph’ instruments are used as an attachment to the telescopes which is designed to block out the glare of stars to resolve the nearby objects. The ‘corona’ which is an aura of plasma extending millions of kilometers into space surrounding our sun is observed with the same technology. 

Earths Magnetic field and CMEs

The Earth has its own magnetic field around the planet. When the Earth is hit by a CME, it is known as ‘Geomagnetic’ or ‘solar storm’. The force of the CME compresses the Earth’s magnetic fields for the duration of this storm. 


When the solar storm originating from CMEs hit Earth's magnetic field, the particles are directed towards the poles. These particles which are mainly electrons and protons, are considered to be the main cause of beautiful lights being generated in Earth’s atmosphere known as ‘Aurora’ or ‘Polar Lights’.

The Carrington Event

It is the most intense geomagnetic storm recorded in the history of mankind. Midday on 1st September 1859, Amateur astronomers Richard Carrington and Richard Hodgson recorded the intense solar flares. During this geomagnetic storm, the CMEs had traveled 150 million kilometers to Earth in just 17.6 hours. 


The auroras were seen all around the globe during this solar storm and could be seen from some regions along the equator. The electrically charged particles from the sun entered Earth's atmosphere and surged telegraph systems causing them to fail. Some events of electric shocks were also reported by the people operating the equipment and some operators could still send and receive signals even after disconnecting their power supplies. 

One more CME hit earth in March 1989, less devastating than the 1859 incident which jammed radio stations and rendered the satellites in orbit useless for hours. 


If today we are hit by CME as powerful as in 1859, It can cause devastation because a large part of our lives is surrounded by technologies driven by electricity. The most susceptible targets being Electricity grids and transformers if turned off can affect billions of people on Earth causing all sorts of issues including Manufacturing, Transportation, Food Production. 

Mankind as a whole is shockingly unprepared for a natural disaster caused by super solar storms of such magnitude.


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Saturday, December 12, 2020

Journey of Spacecraft from Launch to Space Station

December 12, 2020 0

There is a lot that goes on from the ‘rocket launch’ to ‘docking on the space station’ which is already figured out days before the launch. Understanding orbital mechanics is essential for rocket science. 

Step 1: Getting astronauts above the atmosphere 

The Rocket to which Astronauts are strapped, helps them leave the planet’s dense atmosphere and inserts them into an orbit that does not have much of a drag due to the atmosphere. This altitude ensures that the astronauts with the docking vehicle won’t fall back down on earth. The third stage of the rocket cuts off in this ‘Insertion Orbit’ and the astronauts are no longer in a rocket-powered flight. 


Step 2: Hohmann Transfer

It is the most efficient way to move a spacecraft from one circular orbit to another circular orbit with either smaller or larger radii. This orbital maneuver consists of 2 circular orbits(one of which is the destination orbit) and 1 elliptical orbit(Connecting the 2 circular orbits)

Phasing Orbit: The docking module uses its thrusters to increase its tangential velocity which in turn puts the module in an elliptical orbit. This burn of thrusters is performed on one side of the planet and the new elliptical orbit intersects the destination-circular orbit on another side of the planet. Once the module reaches this intersection, it turns on the thrusters again to make its elliptical orbit a circular one(This is Phasing Orbit about 370 km above Earth). This maneuver is known as ‘Hohmann Transfer’ where module waits for the correct location of the Space Station to initiate the next maneuver. 

Step 3: Bielliptical Transfer

This is the orbital maneuver that transfers the docking module from Phasing Orbit to final Spacestation orbit with three engine burns. The first 2 burns put the module in space station orbit and the last burn is a series of correction burns to ensure the right speed and right location with respect to the Space Station. 

Now the Module is ready to make a U-turn in space to face the space station for the docking phase. 


Step 4: Docking

This phase involves aligning the docking module axis to the space station axis while simultaneously closing the distance between the module and ISS. The second step of this phase is to align the module to the correct docking port of ISS. Once this step is concluded, the astronaut crew issues command for the final approach. 


  1. The Probe touches the Docking Hatch.

  2. Thrusters provide one last push to ensure the lock.

  3. Module assembles with ISS.

  4. Docking interface Pressure checks. 

  5. Pressure Equalisation. 

After all the above steps, The Hatch finally opens and the astronauts are welcomed aboard International Space stations with Hugs and High Fives.


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Sunday, December 6, 2020

How To Deflect An Asteroid

December 06, 2020 0

About 65 million years ago, the world of dinosaurs was destroyed by an asteroid about 10 km wide. Such size of an asteroid can have global effects because of the debris it ejects on the powerful impact. It can spread dust clouds over the entire planet and block out sunlight from reaching the surface causing a catastrophe. 

There are over 24,000 near-earth objects detected until now which pose a serious threat to us. One great example of this is the ‘Chelyabinsk meteor’(20m wide), which entered the Earth’s atmosphere over Russia on 15th February 2013. It exploded in the air about 30km high and was brighter than the Sun for a brief moment. The shockwave generated by this blast injured over 1400 people and damaged around 7200 buildings in 6 cities in the region. 


Bomb an Asteroid

Send an explosive rocket system onto a trajectory that meets the asteroid in its path and then detonate the explosives causing the asteroid to blow up. This will turn the asteroid into a rubble pile but if the explosion is not massive enough, the gravitational attraction between these new fragments can still pull everything together. And now we will have an asteroid rain instead of an asteroid hitting the surface in one place.  


Attach a rocket to an asteroid

This involves placing the rocket propulsion on the surface of the asteroid and changing its trajectory just enough such that it misses the earth and flies past it. This is considering that the asteroid is completely a solid body and not collective fragments in which case, the rocket systems can only push one fragment that it is attached to. Even if the asteroid is a complete body, It rotates around its center of mass and so the rocket attached to its surface will be rotating with it making it more complicated to propel it in the desired direction in the required time. 

Using Gravity Tractor

One clever way is to use the gravitational attraction between the spacecraft and asteroid to move it away from the path to the collision. Park the spacecraft near an asteroid instead of landing on its surface, the gravity pulls both these objects together but the spacecraft with thrusters onboard can counter this force and ultimately only the asteroid moves towards the spacecraft pulling it out of the collision trajectory. 


Put a Reflective layer on the asteroid

Cover the surface of the Asteroid with a highly reflective foil such that the side facing towards the sun will have a large number of photons of light impacting the asteroid and reflecting back into space. This will create an equal and opposite force on the asteroid forcing it to move away from the Sun and essentially changing its trajectory of collision with earth. 


Using Powerful Lasers 

Lasers can be used as a powerful weapon against incoming asteroids. The idea is to point the laser on the surface of the asteroid and obliterate it at a point opposite to which it needs to be propelled. This point ejects debris into space and as an equal and opposite reaction to this, the asteroid moves away from its trajectory. The only requirement is to have powerful enough laser systems which we currently do not have.

Asteroid Map

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Wednesday, November 18, 2020

Boundaries of solar system

November 18, 2020 0

A planetary system is a general term used for describing the system of planets and a host star around which these planets orbit. Our Sun is named ‘Sol’ from the Latin word: solis and anything related to it is ‘solar’, Hence the: Solar System. 


Our Planetary system consists of our host star, the Sun, and planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. It also has a number of dwarf planets like pluto, many moons, and millions of asteroids and meteoroids.


The question is: how big is our planetary system? Where can we plot the boundaries and declare that outside is not in our solar system? How far the Voyager 1 and Voyager 2 have to travel to finally be outside the solar system?


Solar Winds

The Sun generates a wind of ionized particles and magnetic field that stream millions of miles into space. This is known as ‘Solar Wind’ which defines the boundaries of the solar system. This can be imagined as a bubble-like region of space created and inflated by our Sun’s plasma(Heliosphere). 


Termination shock

The particles from the sun are emitted at about 400 km/hour. But, as we move farther away from the Sun, the pressure of the solar wind drops as a square of that distance. And eventually, the solar wind can no longer maintain the supersonic flow against the interstellar medium. Here, the wind slows down to subsonic speeds causing compression, heating, and change in the magnetic field known as ‘Termination shock’. It is believed to be 75 to 90 Astronomical units from our Sun.  


Heliosheath

The wind flow is not yet stopped but slowed down due to interaction with the interstellar medium. Outside of the termination shock is the region called ‘heliosheath’ where the flow of ionized particles is turbulent. This region is believed to be at approximately 80 to 100 astronomical units from the Sun.


Heliopause

The outer edge of the heliosheath is known as ‘Heliopause’ where the solar wind does not possess enough strength to counteract the cosmic galactic wind. The protons from the Sun become rare, approaching the Heliopause. This is the theoretical boundary of the solar system where stellar winds from the surrounding stars dominate the region of space. 


Fun Facts

  • Voyager 1 has crossed the Heliopause on August 25, 2012, at a distance of 121 AU(18 billion km) from the Sun. 

  • Because we are revolving around the center of our galaxy, the Solar system grows a ‘Heliotail’ where solar wind ultimately escapes the Heliosphere. 

  • All the planets including Earth, are partly shielded from the galactic cosmic rays due to the presence of the Heliosphere.

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Tuesday, July 7, 2020

Life-cycle of a Star

July 07, 2020 1


Do you ever wonder where did our Sun come from? How long will it keep shining up there?. And what happens in the final moments of the stars that we see as we look up at the night sky.?

The life of a star begins inside a Nebula which is a huge mixture of gas and cosmic dust spread across the vast space. Inside this nebula, Hydrogen gas begins to accumulate due to the forces of gravity and starts spinning. Over time, it generates an immense amount of heat as the gas spins faster and faster. This heat then results in nuclear fusion to take place inside the core of this gas cloud. This is when it begins to glow. Like our star in the middle of our solar system does.   

But how long will it keep glowing? As long as there is enough hydrogen at the core of the star, which is constantly being converted into Helium by the process of nuclear fusion. (Our Sun has about 5 billion years of Hydrogen fuel left inside its core. So we are safe till then!) Once this hydrogen fuel runs out and the process of generating Helium stops, the core of the star becomes unstable. At this point, the star begins to expand outwards and starts glowing red as it cools down, famously known as Red Giant. (When our Sun turns into a Red Giant, it may swallow its nearest planets, Mercury, Venus, and Earth as well. We don’t want to be on this planet to see it happening.) The process of nuclear fusion at the Red Giant star’s core still persists, only this time the Helium is being converted into carbon.


The star will go through the next phase of its life depending on its mass. once the helium fuel runs out at the core of a Red Giant, a Low-mass star like our Sun collapses into a white dwarf, which is a very small and incredibly dense object. This collapse shoots out the glowing ionized gas of outer layers of Red Giant creating a Planetary Nebula (Slightly less awesome, than what happens with the massive stars.). 


When Massive star runs out of Helium fuel in its Red Giant phase, it undergoes a supernova explosion. The explosion occurs due to the nuclei of atoms being crushed up to a point where repulsive forces at the atomic levels overcome the forces of gravity and a shock wave is released from the core seen as a supernova explosion. (fun fact: the brightest of these explosions can outshine a galaxy in which it took place). The star will now turn into a neutron star if the mass of the remaining matter is about 1.4 to 3 times as massive as our Sun. If the core is even more massive than this, The forces of gravity overcome the repulsive forces at the atomic levels and the star turn into a Black Hole (A singular point of theoretically infinite density with an immense gravitational force).


What is Nuclear fusion?

The Process where smaller nuclei combine into larger nuclei having lesser mass than the sum of the parent smaller nuclei. This remaining mass is converted into energy governed by Einstein’s famous equation: E = mc2.


I wonder where will humanity be when our sun is about to explode. Will we be able to find a good spot in the universe to look at this event where our Sun creates a beautiful Planetary Nebula?


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