29 Jul 2019

"Dragonfly 44" A weird galaxy made of 99% dark matter!

A milkyway sized weird galaxy made of 99% dark matter


What we know about dark matter is nothing. From decades we are trying to solve the mystery of dark matter but we still can’t detect them.

We are using very advanced instruments like Hubble telescope and even International space station (ISS) and many more powerful telescopes which is also present on the Earth, but we have not detected them yet.

Here should be a question, if we don’t have detected it yet then how do we know, even it exists?

Well, we know how much dark matter is because we know how much it affects the universe's expansion. Dark energy is roughly 68% and dark matter is 27% while normal matter is just 5% in this universe.
As we haven’t observed dark energy yet, so only we have explanations in the name of information.

This Universe consists 95% of dark matter and dark energy that means we only see the 5% of this universe but the rest 95% is present everywhere as a dominant factor.

Now, what if a milkyway sized galaxy found to be containing 99.99% of dark matter and just 0.01% of ordinary matter?

Astronomers have discovered a galaxy as big as the Milky Way that consists almost entirely of dark matter, a mysterious and invisible substance that scientists have been trying to figure out for decades.

Only one-hundredth of one percent (0.01%) of the galaxy is ordinary, visible matter like stars and planets. The other 99.99 percent of the stuff in this galaxy can't be seen, but their effects can se observed.

This dark galaxy was first detected in 2015 by using Dragonfly Telephoto Array in New Mexico and was named Dragonfly 44.

This Dragonfly Telephoto Array is combination of eight telephoto lenses and cameras, which is designed to look at the objects in the universe which are not bright enough to see from other telescopes.

Also read:-

•what exist before nothing?

•What is dark matter and dark energy?

The String Theory!

Pieter van Dokkum of Yale University and colleagues found the Dragonfly 44 galaxy in the Coma Cluster, 300 million light years from the Earth.

This distance is easily close enough far a telescope to see, as Hubble telescope can se billions of light year away, but still no one noticed these galaxies hidden in dark before.

Dragonfly 44 is one of the largest and the brightest galaxy they have found in Coma Cluster, which is a group of at least 1,000 galaxies. Dragonfly 44 is as big as milkyway galaxy but emits only 1% as much light.

Discovery of Dragonfly 44 galaxy

Pieter van Dokkum and his team realize something unusual about Dragonfly 44, that was a galaxy hold it together with so few stars. There wouldn’t be enough gravity and the stars should drift out. But here the suspect which was responsible for holding the stars and forming the galaxy was the dark matter.

But, how much dark matter? For finding this, they used one of the largest telescope on the Earth, located at the W. M. Keck Observatory in Mauna Kea, Hawaii named Keck II.

They used a tool on the Keck II telescope called the Deep Imaging Multi-Object Spectrograph (DEIMOS) to study the movement of stars in the galaxy.

In their observations, van Dokkum and his team found evidence of way more mass than they could actually see. Only 0.01 percent of the galaxy is made of ordinary, visible matter, that is made of atoms containing electrons, protons and neutrons.

But the other 99.99 percent of Dragonfly 44's mass is the dark matter. Of all the stuff in this Milky Way-size galaxy, we can see almost nothing.

Also read:-

•Einstein vs Newton on Gravity!

•WARP DRIVE, a technology to travel faster than the light!

What happens if you falls into a Black Hole?

"This has big implications for the study of dark matter," van Dokkum said.

"It helps to have objects that are almost entirely made of dark matter so we don't get confused by stars and all the other things that galaxies have.

The only such galaxies we had to study before were tiny. This finding opens up a whole new class of massive objects that we can study."

Although, 47 similarly faint galaxies were observed, far dimmer than the other galaxies within the Coma cluster. How these galaxies form is still a mystery.

Nature reports that a quasar at the heart of the galaxy may have destroyed the gas reserves that normally would’ve formed conventional stars, or that interactions with other galaxies in the Coma cluster might be responsible for the phenomenon.

The team is searching for more massive dark galaxies that are closer to Earth so they might uncover signals that reveal a dark matter particle.

22 Jul 2019

Chandrayaan 2: Full mission report

Chandrayaan 2: Full mission report

Chandrayaan 2

India has successfully launched it’s second lunar exploration missions named Chandrayaan 2, which is the successor of one of the most successful lunar mission Chandrayaan 1.

Chandrayaan 1 was the 1st to discover the presence of water molecules on the moons surface and was operated for almost 1 year successfully.
Apart from it, it had found preserved lava tube that may provide site for future human habitation. And there are many more success story of chandrayan 1.

Chandrayaan 2 mission is conducted by Indian space agency ISRO and has been launched on 22 July 2019, at 14:43 IST using GSLV MK III rocket from Satish Dhawan space centre located at Sriharikota at Andhra Pradesh. 

Earlier it as be launched on 15 July 2019, at 02:51 IST (15 July 2109 ,at 21:21 UTC), but due to some technical issues the launch was cancelled few minutes before the launch time but this time Chandrayaan 2 has been launched successfully.

Total journey time of Chandrayaan 2 will be of 48 days. Chandrayaan 2 will first orbit the Earth for 17 days, then the Chandrayaan will be separated. It will take 5 days to reach in Moon’s orbit after escaping from Earths orbit. After entering the Moon’s orbit it will orbit it for 28 days and finally will land on Moon’s surface.

With successful landing Chandrayaan 2 will become the 1st lunar mission to land near the south Pole of the moon and 4th country to achieve a soft landing on the moon after USA, USSR and China.

Chandrayaan 2 has a lunar orbiter, a lander and a rover. Chandrayaan 2 will attempt a soft landing of rover and lander at the latitude of 70°south in a high plane between two creators,  Manzinus C and Simpelus C.

Moon has the undisturbed record of the nascent solar system environment, so it will be helpful to know the solar system from different way. While there are some models explaining origin of moon and solar system exists but that all needs explanation.

Extensive mapping of moon surface will help us know about different composition on moon and will probably give important piece of information for trace the origin and evolution of the moon.

It has also objective of finding evidence of presence of water molecule on moon which was found by Chandrayaan 1 and the extent of its distribution on lunar surface and subsurface.

Lunar south pole is so important and intresting because, most of its past is completely and permanently covered under shadow and this makes the possibility of presence of water. And also the south pole has craters that are cold traps, containing fossilised record  of the early solar system.

Chandrayaan 2 has total 13 payloads, in which orbiter has 8 payloads, lander has 3 while rover has 2 payloads.

Chandrayaan 2- Orbiter

At the time of launch, the Chandrayaan-2 Orbiter will be capable of communicating with Indian Deep Space Network (IDSN) at Byalalu, Karnataka as well as the lander Vikram. The mission life of the Orbiter is one year and it will be placed in a 100X100 km lunar polar orbit. Orbiter weights 2,379 kg.

Orbiter’s payloads include:-

1. Terrain mapping camera will make digital elevation model of whole Moon;
2. Large area soft x-ray spectrometer will examine the composition of surface of the Moon;

3. Solar x-ray monitor will provide the input of solar x-ray spectrum;
4. Imaging IR spectrometer will find the evidence of presence of ice and minerals;

5. Orbiter will examine the polar region of moon for finding the evidence of ice under the surface;
6. Atmospheric composition explorer-2 will study the environment of Moon;

7. Orbiter high resolution camera will take pictures of the surface the Moon; and
8. Its dual frequency radio science experiment will study the Ionosphere of the Moon.

Chandrayaan 2 Lander – Vikram

The lander of Chandrayaan-2 is named Vikram after Dr Vikram A Sarabhai, the father of the Indian space programme. It is designed to function for one lunar day.

Vikram has the capability to communicate with IDSN at Byalalu near Bengaluru, as well as with the Orbiter and Rover. The Lander is designed to execute a soft landing on the lunar surface. Lander weights 1,471 kg.

Lander's payload includes :-

1. Lander’s instrument for Lunar seismic activity will examine the earthquake movement on the sight;

2. Surface thermo- physical experiment will study the thermal conductivity of the moon; and
3. Langmuir probe will study the surface of the Moon.

Chandrayaan 2 Rover – Pragyan

Chandrayaan-2 rover is a six-wheeled robotic vehicle Pragyan can travel up to 500 metres and leverages solar energy for its functioning. It can only communicate with the Lander. Pragyan weights just 27 kg.

Rover's payload includes :-

1. Rover’s Alpha particle x-ray spectrometer will do detail analysis of Moon’s surface; and

2. Leaser induced breakdown spectroscope will test the surface composition of moon near the landing sight.

Chandrayaan-2 has several science payloads to expand the lunar scientific knowledge through 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.

The mission is scheduled to aboard Isro's Geosynchronous Satellite Launch Vehicle Mark-III. It will cost about Rs 987 crore roughly ($144 million). While China's  chang'e 4 costs Rs 5,759 crores ($836 million).

Isro's lander will attempt a "soft", controlled landing on the lunar surface after 48 days from the time of launch.

After Chandrayaan 2 ISRO is going to plann it's own Space Station. And it will be more advanced than International space station.

15 Jul 2019

What happens if you falls into a Black Hole?

What happens if you falls into a Black Hole?

What happens if you falls into a Black Hole?

Around a century ago, Einstein propose his theory of relativity which predicts that, a body of sufficient compact mass can deform that particular region of space-time to form a big deep dig like structure named as black hole.

This body is really interesting for us since after its discovery because the black holes give rise to many hypothetical concepts which can't be possible it’s without existence.

A body with such a huge gravitational pull, that even light can't escape once trapped in its gravitational pull. It was first considered by john Michelle and Pierre- Simon laplace in 18th century.

In 1916, Karl Schwarzschild proved the existence of a region of space-time from where light can't escape (black holes) by solving mathematical calculations of the theory of relativity.

Formation of Black holes

A black hole is formed when a star of about 10 solar mass used up all his fuel or no further hydrogen is remain in that star then, that's the time of death of a star. At this time the size of star increases rapidly and because of this increasing size the balance between the internal pressure and gravitational force produces by star itself decreases. 

When the internal pressure of a star is not sufficient to withstand its own gravitational force than the phenomenon takes place is known as gravitational collapse. In this gravitational collapse, whole mass of star starts composing into a extremely small point and because of such a huge mass per unit area, that point makes a big dig like curved structure in that particular region of space-time and that point is named as point of singularity.

The area where the curve in space-time starts forming a boundary line for other objects is known as event horizon. Once if light entered in event horizon then it also can’t escape from its gravitational pull.

What will happen if a person jump into a black hole?

Just after jumping inside a black hole, we will observe that our field of view is converting into darkness and after a instant, our whole view will converted into darkness and this part of black hole known as photon sphere.
In the region of photon sphere, black hole doesn't let light to escape from it and do not pull them also but in this region light rays orbits the black hole and form a circular ring so when we enters in this region and try to look side ways then the person may see himself because the reflected light from our eye can return back to our eye.

Because of such a huge mass back hole wrap  space along with time so if someone will try to see the man inside the black hole then he will see that the person is going inside the black hole very and very slowly and when the person reaches the event horizon then he will disappear for the outer person.

Things are different for us, the light coming from the universe will transform into a small circle and for how much time this phenomenon will continue is depend on size of black hole.

After entering into the event horizon off course we will be dead because of infinite gravitational pull. After crossing the region of event horizon, there will be a great difference in force of gravity on our head as compare to leg part and because of this variable gravity, our body will open like thread on atomic level and compressed into the singularity.

Is this universe not real | Are we living in computer simulation?

Are we living in computer simulation?

Are we living in computer simulation?

We are putting so much efforts in research, only to get answer of one question, One big question, who created us. This is the ultimate question for humans since they started thinking about their origin.

Theory of big bang tells about origin of this universe but didn't say anything about what's the actual reason of big bang and we all know that this theory is not perfect and there are many people raising questions against big bang, so the most satisfying theory is also theory under question.

To get the answer of this ultimate question, some philosophers and researchers proposed a hypothesis known as simulation hypothesis. According to this hypothesis our universe is not real  but a program which is running with some codes, like games.

Yes this is sounds like a weird hypothetical concept but this hypothesis has its points and chance of possibilities. For understanding this hypothetical theory its necessary to have some basic knowledge about, how the computer game works.

A Computer game is a software working on some specific codes, this means all the laws of physics can be programed, by using some codes only.
For making a game like real life, developer follow some real life basic principles, which makes game more interesting.

Now if we assume our universe as a programed game then it will be observed that there are some non violating laws in the universe like in the games, like every object get attracted by every other object with gravity.

The philosophers who believe in this theory has give some points to prove it:

Perfection of universe-

why the earth is so favourable for life?

Means earth rotates the Sun by maintaining the distance where the temperature of earth remains suitable for life and this distance is known as habitable zone. 

Another noticeable fact is, if Dark energy would present in stronger way than that write now, then there will be no life on any planet of universe.

Why everything on earth is so logistic about earth? 

It could be possible, that everything about us and about this universe should be coded by some programming just like computer games.

Dual nature of electron-

Young's double slit experiment tells when light passes through a perforated slit then it clearly shows particle nature, as accumulation of photon takes place.
When water is passed through that slit then, it shows wave nature by forming some ripples and wave front just like nature of wave.

In the next experiment when electron is passed though that slit then it shows predicted behaviour which is just like in case of water.

And when this experiment was performed again, then this time scientists were observing it very sensitively and the result of experiment was totally shocking.

Whenever scientists was observing the nature of electron over this experiment then electrons were showing particle nature as it was striking the second slit just like a particle.
It seems like, electrons were knowing that someone is observing him. We can say that reality is creating by our observation just like it happens in games.

In games, we don't have any idea about what's going to happen in next phase or next level but those phases are already programed by someone.

Theory of relativity-

Around a century ago, Einstein proved that the speed of light is a kind of speed limit of universe. That means, any object having mass can't travel with the speed of light.

Theory of relativity also proves that as fast an object travels the time gets slower for it. This phenomenon is known as time dilation.

According to simulation theory, our universe updates itself for observing all conscious bodies. This speed is many time faster than today's computers but these speeds are similar to the frames per second in games.

If The FPS of a game is increased in setting then the game starts lacking or getting slow down. So we can say that if any body is travelling with the speed of light then for that body, updating of the universe stops at that instant.

Quantum entanglement-

we all know that every particle has its own spin just like stars and planets and that spin is known as particle spin. But this is already proved that, this concept of unidirectional spin of particle comes around when we observe any particle and without our observance every particle is present in every possible spin and this state of particle is known as superposition state. 

If we make two particles from one then the spin of particles will be opposite to each other due to law of conservation of momentum. When an observer, starts his observation on any one particle then at the same instant the spin of second particle becomes opposite to each other.

If we separate those two particles with distance of some light years still then, this phenomenon will work as it is and that means the information of a particle is transported with more than the speed of light and this is against the theory of relativity. 

We don't have any answer of this question that how this phenomenon takes place?

According to simulation theory, when two particles entangled with each other then, two systems which are operating those particles combine and works as unity and this means those two particles or pixels can be operate from a single system so information can be transferred with the speed faster than the light.

Presence of computer codes in universe-

Maths is the only weapon to counter the mysteries of universe. Maths can be easily transformed into computer codes and that means, it is possible that we can transform each and everything of universe into computer codes.

Right now we can't do that because we don't have such type of computers but in future, it is not going to remain as a impossible task.

String theory is the only theory which explains about the universe before big bang and after studying this theory scientists find that there are some computer codes which is present in the universe.

Now we can simply assume that if we become capable to make a programed world in future then it is also possible that some civilization has already done it and our universe is just a simulated computer world.

8 Jul 2019

Black hole can be formed without Stars, rescent study suggests!

Black hole can be formed without collapsing the Star, rescent study suggests!

The word Black hole starts up a new circulation of curiosity in our mind. The simple reason behind this curiosity in topics related to black is, this object can make some of the dream and  hypothetical phenomenon possible.

In 1915, Albert Einstein had given his theory of general relativity in which he described, how gravity influence light waves.

Few months later, Karl Schwarzschild found a solution to the Einstein field equation. This equation describes the gravitational fields of a point and circular mass body showing that the body like black hole can be possibly present in the universe.

The idea of a object from which light can't escape was firstly given by John Michelle in 18th century.

Because of great mind like these, today we know most of the facts of black hole. Let's know more about them:
A black hole is a region of space-time exhibiting such a huge gravitational pull that once anything entered in the area of its gravitational pull then, their is zero percent chance that it will be back.

Even light (fastest in the universe) can't escape from the gravitational pull of a black hole. This is also a reason that we don't have enough information about black holes because we can't explore them enough. Still we are continuously trying to know more and more things related to a black hole.

Normally, a black hole forms when a star of at least 10 solar mass has already spent all its hydrogen and helium as a fuel and then it collapse. This collapse is known as gravitational collapse and it occurs when an object's internal pressure in insufficient to resist it from its own gravity.
This is a usual method of formation of a black hole.

Recently, a paper published in astrophysical journal letters by researchers Santana basu and Arpan das of university of western Ontario, in their paper they explained about how black hole can be formed without imploding of a star.

In this study, researchers explains that how supermassive black holes grow very faster and suddenly at a certain period of time their growing stops.

In this paper, they also explain that how black holes formed at the initial phase of our universe. Santana basu and Arpan das are clearly explained that how black holes form with direct collapse rather than Steller remnants.

Basu explained, supermassive black hole have a very short period of time where it increases its mass and size very-very quickly and after some time their production came to half because of radiation present in the universe created by other bodies.

In their research paper, they also mentioned a fact that researchers have discovered numerous black holes in the last decades whose mass in billions time the mass of the sun.

These facts related to black holes makes it more interesting and informative and this is the reason why researchers are giving their so much time and focus to these intelligence bodies.

Einstein vs Newton on Gravity!

Einstein vs Newton on Gravity!


Newton discovered the force of gravity about 300 years ago, in which he states that every particle attracts other particles in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of distance between them.

His equation was able to calculate the force of gravity accurately without any errors. In fact we are using only the law of gravity during a rocket launch.
Later the equations of universal gravitation takes a different form, which is:

Where F is the gravitational force acting between two bodies, m1 and m2 are the masses of the bodies and r is the distance between the two bodies.

First test of newton's law of gravity was perform by British scientists Henry Cavendish, approximately 77 years after newton's death.

Law of gravitation also provides one of the most useful formula which is inverse square law. This law is same in coulomb's law of electrostatics. In actual this law was prepared by Newton and Robert Hook together.

Everything was going absolutely right until a clerk of Swiss patent office named Albert Einstein propose his special theory of relativity. This theory changes everything in the world of physics.

Einstein confronted the two famous theories of that time which were, newton's theory of absolute space and time and Maxwell theory of constant speed of light.

According to Newton, gravity is an instantaneous force which means we will feel all its effect at the instant at which it starts effecting us. Einstein confronted both these theories by proposing his special theory of relativity. 

Einstein propose special theory of relativity, in four  papers in which he explains, how laws of physics didn't change for objects moving in initial frame of reference and also proved the independent speed of light.

Einstein then challenged the newton's concept of gravity as a instantaneous force. Einstein explain this by taking the example of the sun.

Today we know that earth revolve around sun due to its gravitational force and this concept was given by Newton. So lets assume, what happen when suddenly sun disappears?

According to Newton, we will able to know this event at the same instant when sun disappears and our earth starts moving in a straight line motion. Einstein raise his question that if light take about 8 minutes to reach earth then how it is possible that we will feel the absence of sun's gravity in the same instant and if it really happens which means gravity has a greater speed than light, which is impossible.

Einstein then proposes his model of space time fabric. In this model he suggests that if we consider everything (space, matter, energy, time) as a fabrics present in empty space then we will able to find the reason of gravity.

He said that, every heavy mass object make a curve in space time fabric and due to this curve other lesser mass objects starts rotation around the object and same with earth and the sun.

So, when we consider gravity after this space time fabric model then we can clearly visualise that, after disappearing the sun, it will take some time to re-establish the fabric of space time and this time will of course more than 8 minutes.

By this way Einstein proved newton wrong and for doing this he also provide the reason of gravity, which is more important.

1 Jul 2019

Scientists examine the science of teleportation successfully!

Scientists examine the science of teleportation successfully!

Scientists done the science of teleportation successfully!

Today, most of the people have some idea about quantum physics and its weird world. Quantum physics talks about a different world of quantum particles where our physics’ laws stop functioning. Even Einstein wasn't able to understand this weird physics.

Neil Bohr in a interview said "if anyone is saying that he understood quantum physics then either he is lying or he is a fool". In this way we can understand that we can't understand everything about quantum physics but still we can take some ideas and help from it in future.

Quantum teleportation is one of the phenomenon which can help humans a lot in future in different ways.

Quantum teleportation is a process by which information is transmitted from one region of space to any other region with the help of communication and previously shared quantum entanglement between the sending and receiving region of space.

By listening the word teleportation, it seems as any object is teleported from one place to another. But that's not the case with quantum teleportation.

In actual teleportation, an object is dematerialised from one place and materialised at any other place. But in quantum teleportation, rather than teleporting any object, an quantum information is teleported.

After reading this, most of the people will think, in this case why we call it quantum teleportation rather than calling quantum communication.

Well this is because, if we transfer all the information of a particle A in any other particle B than it will seem as whole the particle is teleported because B starts behaving like A and because of this phenomenon we call it quantum teleportation.

Lets take example for understanding this in an easy way. Two friends A and B are separated by any distance. A have a photon named as C and he wants to teleport it at B, so they need a pair of entangled particle D and E.

Because entangled particles are interacting with each other if we get the spin of D is up after measurement then of course the spin of E will be down.

According to superposition principle, D and E is present in both the state up and down until we measure it. For making teleportation successful A will measure C and D in combined state rather than measuring them individually and this type of measurement is known as bell measurement.
After measuring, C starts interacting with D and because D is already interacted with E all the information of C will Move to E through D.

Now all the information of C is transferred to E but B didn't know that so here A have to use some classical communication channel to share some information.

After getting the information B can manipulate the particle E and make it as C. Here, no cloning and no deleting theory applies according to which, we can't copy or delete the information of a quantum particle.

Because of this theory, when the information of quantum particle C is teleported to E then at that instance the quantum particle C will changed into any other particle with any other information.

Now the arisen question is how this phenomenon can help us?

Actually this can make our communication system hacking proof. Lets understand this with same example, when A does the bell measurement of quantum particle C and D then he gets the relation between C and D.

Let the relation comes out is, C is opposite to E and after getting this information he share it with B. Here, if anyone is tapping there phone call then he can't get the sufficient information because A share B that C and D are opposite to each other and after getting this information, B will measure his particle.

After measuring if he gets the spin of particle up then he will understand that the spin  of its entangled particle is down and by this way he will predict that the spin of C is up. After getting this information if B manipulate E than he can make it as C and the state of C has changed already so we can say that the particle C is teleported to B.

International Space Station: First step towards space colonization|

All about International Space Station!

International space station

By early 1980s, Europe was on high due to the success of spacelab laboratory and Ariane launch rocket and now they were debating on idea of permanent manned space station which was came during the spacelab laboratory mission.
During the same time space planners of USA have the same thought, but that time they were concentrated more on developing space shuttles instead of space station.

But, the Soviet Union was  working on this idea, and on 19 April 1971, Salyut 1 was launched in orbit and was a critical step towards making permanent place for human in space. Year 1977, see the launch of second generation space station in the shape of Salyut 2.

And, Frenchman Jean-Loup Chrétien became first western astronaut to spend time in space after the launch of Salyut 3 in 1982, as he spent two months in space.

On 20 February 1986, Soviet Union established third generation space station “MIR” (multi-modular space laboratory)  300 Kms above in the Earth’s orbit. Mir was designed to last for 12 years, it gave western scientists opportunity for long -term researchers, later in March 2001 it was crash landed in Pacific ocean successfully.

During 1980s, NASA was searching for ways to keep astronauts in space for a long period of time. Along with it, they were also looking for  scientific experimental setups and commercial applications.

In 1983, USA along with Europe, Japan and Canada came together around a table for discussing about the possibility of join space station. And on 25 January 1994, NASA was tasked for developing permanently manned space station to be used for scientific and industrial research and for the manufacture of metals and medicines.

Later, counties like France, Germany and Italy joined this space programme  with their advanced technologies. France helped mainly with launch vehicle and Germany and Italy with their complex technical supports. As its launch was scheduled for 1992, but due to delay it was launched on 20 November 1998.

Main reason of this delay was the annual budget negotiation in in US Congress and other problem was the different vision of nature of Space Station.

Like, whether it should be a research laboratory or an future orbital interchange for the future manned exploration missions. After that all the loss of Space Shuttle Challenger in 1986 set the programme several years back.

In 1993 NASA has invited Russia to join this space mission. After the  approval of other partner countries in 1994 Russia finally joined the program. The benefit of joining Russia was very beneficial, as Russia had very much experience of the space missions and had many well classified and experienced engineer.

Now they have an extra partner which helped them in budget distribution and also they get help by Russia by training their astronaut in Russian Space Station Mir.

Finally on 20 November 1998, International Space Station was launched and get stabilized in the earth’s Orbit at the hight of 400 kilometre.

International Space Station was ninth Space Station to be inhabited, followed by Soviet Union's Salyut, Almaz, Mir as well as Skylab by US.

Space Station has been visited by astronauts, cosmonauts and space visitors of 18 countries. We will talk about it later in detail.

International Space Station completes its revolution in 92 minutes with the speed of 7.66 km/s (17,100 mph) as 15.5 revolution per day.

The original purpose of International Space station was to be  laboratory, observatory, and factory while providing maintenance, transportation and to be used as low Earth orbital base for future missions to be on Mars, Moon and asteroids.

Later in 2010, due to the change in United State space policy, International Space Station had given additional role for the commercial, diplomatic and educational purposes.

International Space Station provides platform for scientific research with powder, data, cooling and crew available for conducting experiments, it also provides platform for small on uncrewed spacecrafts for experiment.

ISS is used for conducting experiments in a wide variety  of fields including astrobiology, astronomy, physical sciences, materials science, space weather, meteorology, and human research including space medicine and the life sciences.

One of the most notable experiment of ISS  is Alpha magnetic spectrometer (AMS) which is for detecting dark matter and to find out other fundamental questions about universe. In April  2013 scientists have reported that AMS may have detected the hint dark matter. And according to NASA it is as important as Hubble Space Telescope.

Medical researches conducted in International Space Station had improved the knowledge about long term exposure of human body in space including bone loss, muscle atrophy and fluid shift. Data of 2006 suggest that astronauts should have suffer bone fracture and movement problems after long time  space exposure and it takes 6 months to reach to Mars.

For the educational purpose ISS provides opportunity  for student of Earth by running student developed experiments and keep providing educational materials and information in the form of audio, video or links and also helps in more different ways.

If we talk about the systems used in the International Space stations, so it provides earth like atmosphere and air pressure and also has the same air composition that of the Earth. Fully oxygen system is not given due to the high fire risk, which was the cause of Apollo 1 crew death.

ISS uses radio signal for communication between system and mission control centre. Radio signals has been also used for  rendezvous and docking process for audio and video communication with crew members, controllers and family members.

International Space Station is the most expensive single item ever constructed as it costs $150 billion as per 2010. Each person day cost it is about 7.5 million which is still half of the per day person cost of the Skylab which costs $19.6 million.

Crew members of ISS still are not so safe because they have to face radiation and the Space Station is just personal protective from radiation. And in the case of solar wind and solar flares they got warning just for a minute but Space Station has a special chamber which is first design for such type of hazards.

In 2019, when two astronauts who have spent more than a year in space got tested the doctor were shocked because they found some long lasting changes including DNA alternation and cognition when one of the astronaut was compared with his twin.

They have to also face psychological stress, muscle atrophy, weakness of bone, loss of body muscles, microbiological environmental hazards, and for overcoming their effect they have to also concentrate more on their health and have to keep exercising.

The most interesting fact about International Space Station is that it is visible easily from our naked eyes as a white moving dot in the sky which occurs due to the reflection of the sunlight and that makes it the brightest artificial object artificial object.

It is visible easily during the sunset and sunrise as it takes 10 minutes to cross a horizon. In 2012, NASA started service “spot the station” through which NASA sends a alert message when the station is going to pass through their City.

Although the space station is visible from 95% of inhabited lands but not visible from extreme South and extreme North portion of the globe.

In March 2019 for the first time 236 people from 18 countries have visited the Space Station and NASA is planning to open the Space Station for visitors.

The United States sent 149 people, Russia sent 47, nine were Japanese, eight were Canadian, five were Italian, four were French, three were German, and there were one each from Belgium, Brazil, Denmark, Kazakhstan, Malaysia, the Netherlands, South Africa, South Korea, Spain, Sweden, and the United Kingdom.

The mission of International space station is extend upto 2030, while India is planning for its own Space station that will initiate after launching Chandrayan 2 on moon by India.