Revolutionary software in lunar research – PHOTLUN

Posted on August 20, 2009 by

Virtual lunar Atlas is a program that allows us to observe and study the moon and its surface. It was developed by Christian Legrand and Patrick Chevalley. This program is basically developed for  cheering  special interest for astronomers, amateurs, and all those interested in exploring the Earth’s natural satellite- The Moon. Due to its precision and detail of its data, Virtual Lunar Atlas has won the recognition of astronomers and prestigious scientific publications. Now it is downloaded more than 500 000 times all over the globe. It has been referred in Chandrayaan 1 lunar mission preparation (India). It is also been recommended by the European Space Agency (ESA) and the French Ministry of National Education.

Photlun is picture manager which has changed the perspective of scientists and researchers towards geographical features of moon. This software allows us to modify pictures, photos of moon’s surfaces in a never done approach using programs that are inbuilt in it. This allows scientists to accurately plan landings of lunar modules or study characteristic features on the surface of moon.

Photlun is basically a Virtual Lunar Atlas which help in finding and studying selected topographical areas on moon. This atlas also contains some 3D views of areas, can be used to check the longitude, latitude and elevation of craters on surfaces with the specific programs available. Even pictures of a surface that is not clearly visible on some areas can be improved by enhancing the brightness, contrast and sharpness or enlarge by its specific commands and features.

a)In this snapshot of working of PhotLun one can study the topology in detail as never done before.

b)One of the many high quality pictures provided by PhotLun. You can clearly verify its unique resolution power.

The latest super- high resolution LOPAM texture built on USGS data improves a lot formations regarding findings and vision

This software gives an added advantage by proving 450 High Resolution [HD] images of lunar surfaces taken through various satellites which orbit moon. Its powerful software configuration is compatible with many operating systems including MacOS and Windows Vista thus enhancing its adaptability and compatibility with latest hardware in the market.

The program’s basic interface is available in two languages i.e. English and French, however extra translations can be freely downloaded from the developers’ website.

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When will man land on mars?

Posted on August 18, 2009 by

The Red Planet has interested mankind when Mars was seen as a small dot in the sky in the earlier days. Humans chose to explore Mars as it was the planet which was closest to Earth. The primary reason why the planet was named as Mars was because it appeared as a small red dot in the sky and hence named after the Roman God of War. Mars has solid ground which most of the other planets don’t have. Mars has a magnetic field which is useful in deflecting gamma rays from the sun and prevents them from reaching the planet. Mars has frozen water in the form of glaciers. All these reasons made man to explore Mars as most of the characteristics resemble the earth.

As of now, three space agencies are competing hard to be the first to Mars. In early 1960’s to 1970’s NASA sent several spacecraft to get pictures of Mars. All of these spacecrafts were of unmanned type. So far 36 unmanned spacecrafts had been sent by various space agencies. They considered sending unmanned spacecrafts as their first step of success. But the sad thing is that most of the unmanned spacecrafts never returned back to earth although they sent back the pictures of Mars. The European Space Agency has planned a mission named “2011 – 2014 Mars Sample Return Mission”. It mainly focuses on taking a sample (1/2 kg) of Martian rocks and return back to earth so that geologists could analyze on the rocks. They consider it as their second step towards Mission to Mars. Also plans for collecting Martian air, dust and frozen liquid is under progress.

Russia is trying to compete with America in the space race by planning to launch a manned spacecraft to Mars though they have failed several times in the earlier missions. Various research studies revealed that 2018 will be the best year to explore Mars considering the solar activity and planetary orbits. Russia has decided to launch a spaceship which will carry people to Mars on May 8, 2018. But NASA and the European Space Agency treat it as a big risk to send people to Mars because they feel that they still have more time to explore before they send people in spaceship. The technology in 2018 will give you the answer for the question of whether Russia will be able to make it to Mars with a manned spaceship. To study the effects of gamma rays on human, NASA and the European Space Agency have begun conducting experiments on moon to study the effects.

Cost factor adds difficulty to the mission because building a manned spaceship weighing 600 tons makes it to be built in space as propelling such a large spaceship is not possible with our current rocket power. NASA estimates that their Mars mission program will cost 388 billion dollars. Although several arguments prevail on the necessity to explore Mars, scientists believe that it would save mankind in case a major catastrophic event destroys the earth.

There had been also plans for cost cutting and make it slimmer through a mission named “The Mars Direct Plan”. They propose new ideas to make the spaceship smaller by cutting down the supplies and limiting the number of things to be taken. Medical experts believe that a manned mission to Mars should not be conducted unless we study about the effects of cosmic rays on human as cosmic rays are prevalent in the outer space.

Even though reaching Mars in the near future, with current technology, would be dangerous and expensive, it would a possibility. NASA and other space agencies are not sure of taking a risk and sending people to Mars. However, the answer to the question of when will man land on mars lies entirely on the technological growth and the cost of the mission. If a technology enables manned mission to mars at an affordable cost with safety, then that will be the day of man’s footprint on Mars.

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Gone are the dark clouds that made “Hubble” blind….

Posted on August 13, 2009 by

Astronauts from the Atlantis on Thursday gifted the Hubble Space Telescope with a deeper insight into the universe in the form of a new farsightedness-special camera eye during the arduous spacewalks to fix the renowned observatory. It gives Hubble the power of looking substantially further into the horizontals and verticals of the universe than earlier models.

“We gave Hubble a hug, and in traditional Hubble fashion it threw us a few curves” said Grunsfeld, who led the spacewalk and along with his partner Andrew Feustel fixed the telescope in a more than seven hour outside expedition.

Replacing Hubble’s old imager with a $132 million “Wide Field Camera 3” will offer it the power of probing deeper into the evolution of universe and revealing the unsolved mysteries of dark energy and matter. The universe being 13.7 billion years old, it is designed to look back 500 million years post birth of the universe. They also fixed a key computer controller unit that beams images to Earth, sending information about our planet.

Astronauts John Grunsfeld and Andrew Feustel installed wide field camera and data router on the Hubble Space Telescope. The 7 hour, 20 minute expedition took almost an hour longer than scheduled.

The other items of Space Agenda:

The spacecraft Atlantis was launched on Monday on an 11-day shuttle mission to renovate the telescope and extend its life till 2014. Wide field camera installment was among a total of five outside applications in the “Hubble” which was anchored with the claw of the shuttle on Wednesday.

For Friday the substitution of several batteries and gyroscopes is aforethought. The gyroscope measures the attitude when Hubble is changing its pointing from one target (a cosmic body) to another, helping to control the telescope’s pointing while scientists are observing those targets.

While the third space walk on Saturday is about the installment of “Cosmic origins Spectograph”. This will allow hubble to have unique looks at weakly radiating cosmic objects in the range of the ultraviolet (UV) to visible radiations.

The most necessitating task is the repair and equipping of “Space Telescope Imaging Spectrographs” which is scheduled during the seventh day which is no more functioning since 2004. Besides, the astronauts also have to attach about 100 small screws. In addition, they should back the isolating “steel covers” which will protect the very sensitive parts of Hubble against the huge temperature variations, which is normal in space.

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The degenerating dwarf

Posted on August 4, 2009 by

The term White Dwarf was first coined by Willem Luyten. A white dwarf also known as degenerate dwarf is a small star composed mostly of electron-degenerate matter. It has mass comparable to that of the Sun and, its volume is comparable to that of the Earth hence, it is very dense. Stars comparable to the size of the sun turn into white Dwarfs once their nuclear fuel is exhausted.

Star – Red Giant – White Dwarf

(White Dwarf Evolution)

The stars whose mass is not too high have White Dwarf as their final evolutionary state, such stars comprise almost 97% of the galaxy. Stars generate energy by hydrogen fusion process. Once such mass is exhausted, this star expands into a red giant, where helium is processed into carbon and oxygen. Technically this process is known as the triple-alpha process.

A red giant must have sufficient mass to generate the core temperatures required to fuse carbon; an absence of same will lead to build up of inert mass of carbon and oxygen at its center. Such stars then expel their outer material, creating what is known as planetary nebula. Only the hot core of the star remains. This core then becomes a young white dwarf, which cools down over the course of the next billion years or so usually, therefore, white dwarfs are composed of carbon and oxygen.

Some facts:

  • Average density of earth: 5.4 x 103 kg/m3
  • Density of earth-sized white dwarf :1 x 109 kg/m3

Thus a white dwarf is 200,000 times as dense as earth.

In general electrons with the same spin are not allowed to occupy the same energy level by Pauli Exclusion Principle. Moreover in normal gas there are not enough electrons floating around to completely fill up all the energy levels. But in a white dwarf, all of the electrons are forced close together; soon all the energy levels in its atoms are filled up with electrons. If all the energy levels are filled, and it is impossible to put more than two electrons in each level, then our white dwarf has become degenerate. For gravity to compress the white dwarf anymore, it must force electrons where they cannot go. Once a star is degenerate, gravity cannot compress it any more because quantum mechanics tells us there is no more available space to be taken up. Thus further collapse is prevented due to quantum mechanical principles. The white dwarf can have only certain amount of mass. Subrahmanyan Chandrasekhar discovered this limit to be 1.4 times the mass of our Sun. (This is appropriately known as the “Chandrasekhar limit”.)

Due to extremely high surface gravity the atmosphere is close around it and is of a very thin layer. The heavier atoms in its atmosphere sink and the lighter ones remain at the surface. Some white dwarfs have almost pure hydrogen or helium atmospheres. The White Dwarfs remain a very challenging field for scientists.

White dwarf star Sirius

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The black void that fills the Universe (black holes)

Posted on August 2, 2009 by

Often considered as cosmic vacuum cleaners, black holes are much more mysterious as well as interesting, captivating minds of both scientists as well as common people. In fact, they are the evolutionary end point of massive stars.

An overflowing BLack hole from Galaxy Centaurus A

To gain more insight into what they actually are, we need to look into some more important points about them. When stars at least 10 to 15 times larger than our own Sun undergo supernova a fair amount of stellar remnant is left. Such stellar remnants have no outward forces to oppose gravitational forces and thus, this remnant will collapse in on themselves. This process of collapsing continues until stage of zero volume and infinite density is reached. Now, it is much easier to understand how black holes get their name. As gravitational forces are extremely high, it is impossible for photons generated by their respective black holes to escape such high gravitational force. Hence, no light rays come out of it and thus the name black hole.

Black holes don’t suck anything that comes along their path. Instead only when anything crosses inside the Schwarzschild radius they are sucked by the black hole. Once inside this radius the escape velocity is almost equal to velocity of light.

The Schwarzschild radius can be calculated using the equation for escape speed:

V (escape velocity) = (2GM/R) 1/2

For photons, or objects with no mass, we can substitute c (the speed of light) for V (escape velocity) and find the Schwarzschild radius, R, to be:

R = 2GM/c2

Now an important question arises: If black holes cannot be seen then how are they detected? Whenever black hole passes close to another normal star or interstellar matter, some of the matter is accelerated towards the black hole. This matter in turn gains kinetic energy and heat is generated. The heating ionizes the atoms and at temperature of about few Kelvin X- rays are emitted. This X-ray emitted falls sporadically causing random variation in their intensity. This variation is easily detected and observed.

Among many other candidates, Cygnus X-1 (Cyg X-1) is the longest known of the black hole candidates. It has a highly variable and irregular source, with X-ray emission that flickers in hundredths of a second.

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All about Neutron stars and Pulsars

Posted on July 30, 2009 by

Neutron star

Neutron stars are a type of remnant that can result from the gravitational collapse of a massive star during a Type II, Type 1b or Type 1c supernova event. They are almost entirely comprised of neutrons and hence the name. Neutrons are those sub-atomic particles that have no electrical charge and have a mass equal to that of the protons.

A neutron starhaving wayward wake

Development:

The core of a gigantic star is fully compressed during a supernova. It then collapses into a neutron star and it maintains most of its angular momentum. When a neutron star is formed, it has a very high rotation speed, and then it slows down steadily. This rotation period of neutron stars ranges from 1.4ms to 30 seconds. Since the neutron star is very compact, it makes way for a very high surface gravity to a value of up to 7*10¹²m/s².

Characteristics:

The gravitational field at the star’s surface is almost 2*10¹¹ times stronger than that of earth. The escape velocity is rather large with the value of 100,000 km/s, which is about one third the speed of light, therefore hosting an immense gravitational field. This strong gravitational field acts as a gravitational lens and makes the radiation emitted by the star to bend thereby making parts of the normally invisible rear surface to become visible.

A neutron star is so solid that one teaspoon of its material would have a mass of over 5*10¹² kg. The resulting force of gravity is so strong that, if an object were to fall from just one meter high it would only take one microsecond to hit the surface of the neutron star, and would do so at around 2000 kilometers per second. The temperature inside a newly formed neutron star is unimaginably high. It ranges from 10¹¹ to 10¹² Kelvin.

As mentioned above, the neutron stars rotate at a very high speed when they are newly formed. This high rotation speed is due to the conservation of angular momentum. Over time, the neutron star slows down it speed. The reason for this is because their rotating magnetic fields radiate energy and so older neutrons may take up to several seconds for each revolution.

Examples:

PSR J0108-1431, LGM-1, PSR B1257+12

Pulsar

Pulsars are also a type of neutron star. They are highly magnetized, rotating neutron stars that emit a beam of electromagnetic radiation. The time period of their pulses may range from 1.4 milliseconds to 8.5 seconds. The electromagnetic radiation can only be observed when the beam of emission is pointing towards the earth. This effect is known as the lighthouse effect. However, the premise of how the pulsars emit their radiation still remains as a mystery.

Pulsar

The first pulsar was observed in July 1967 and at first, the scientists who discovered it were quite taken by surprise since it seemed out of space to them. The word “pulsar” was then coined from two words – “pulsating star” in 1968.

Theory:

As we know, a beam of radiation is emitted from a neutron star each time it rotates. The origin of the beam is attributed to the axis of the magnetic field which might be deviated from the rotational poles by a wide angle. The source of the energy of this beam is the rotational energy of the neutron star.

Classifications:

Rotation-powered pulsars

Accretion-powered pulsars

Magnetars

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The Origin and Extent Of The Universe

Posted on July 28, 2009 by

There are several theories involving the conception of the universe. Out of the various theories the one which got strongly established is that of the Big Bang theory. According to this theory, universe began due to a tremendous explosion from a single point that resulted in the release of tremendous amount of matter and energy and the creation of space and time itself. The age and size of the Universe can be estimated from this theory. Firstly, let us take the age of the Universe into account. How old is the Universe? It can be estimated in two ways:

  • Interpolation of Big bang theory
  • Estimating the age of old stars which are the cluster stars.

The globular cluster stars are some of the densest clusters of stars in the Universe, and it serves as a cosmic clock because of two reasons:

  • Each star belonging to a globular cluster would have formed around the same time.
  • The oldest form of these cluster of stars were formed around the time after the Big Bang theory took place.

In order to determine the age of the globular stars, astronomers measure the distance of the stars from the sun using the yardstick “light year”, which is nothing but the distance traveled by light in one year. According to this method, the origin of the Universe was estimated to be between 11 and 18 billion years ago. The disadvantages of this method are listed below:

  • The exact distance from our planet to a globular cluster cannot be determined.
  • We tend to miss out on the intricate details of stellar evolution.

The second method uses the Hubble constant current, which is the measure of expansion rate of the Universe for its estimation of age of the Universe. This will in turn, help the astronomers to extrapolate back to the big bang. The Cosmologists estimated the age of the Universe to be around 12 to 14 billion years, by using this method.

Next, let us come to the size of the Universe. The extent of the Universe can be estimated using the Doppler effect of light. That is, the change in the intensity of light depending upon whether the rays of light are approaching or receding. When we measure the light from all the distant stars, we find using the Doppler shift in light, that these stars are receding from us. This made the astronomers lead to the conclusion that the Universe is expanding, as a whole.

Now, imagine a balloon which keeps expanding as you blow air into it. As it reaches the optimum elasticity, it is bound to burst. Now apply this logic to the Universe. If you do apply this logic, you can see that the universe will keep expanding, until it can expand no more. When the capacity has maximised, it is expected to implode and start from scratch again. This cycle is also expected to repeat again and again. In conclusion, the Universe may be considered as a phoenix, which can be born from its own ashes.

Black and white Universe

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Remnants of a Stellar

Posted on July 24, 2009 by

Most of us know or have at least heard of White dwarfs, but the concept of Black Dwarfs is relatively newer and less heard off. A black dwarf is a hypothetical stellar remnant, created when a white dwarf becomes sufficiently cool so that it can no longer emit significant heat or light.

As we know, the stars whose mass is not too high become White Dwarfs in their final evolutionary state. Stars generate energy by the hydrogen fusion process. Once it’s mass is exhausted, this star expands into a red giant where helium is processed into carbon and oxygen. Technically, this process is known as triple-alpha process. Red giants must have sufficient mass to generate the core temperatures required to fuse carbon; an absence of the same will lead to the build up of inert mass of carbon and oxygen at its center. Such stars then expel their outer material, creating what is known as planetary nebula. Only the hot core of the star remains. This core then becomes a young white dwarf. When this white dwarf is made up of a dense ball of electron-degenerate matter, it cools slowly by thermal radiation, eventually becoming a black dwarf.

The time required for a white dwarf to actually cool down enough to the state of Black Dwarf is calculated to be longer than the current age of the universe which is that of 13.7 billion years. Hence, no black dwarfs are expected to exist in the universe. Also, Black dwarfs would emit almost no radiation and thus, it becomes extremely difficult to detect them practically. In spite of this, theoretically it is expected to be detected by gravitational influence.

(Black Dwarf Evolution)

Star -> Red Giant -> White Dwarf->Black Dwarf

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Supernova – A radiant process

Posted on July 20, 2009 by

In simple terms, a supernova is a stellar explosion. They are extremely radiant and can cause a burst of radiation which can briefly outshine an entire galaxy, before fading away from view over several weeks or months. During this period, the energy radiated by supernovae can be as much as the energy emitted by the sun. This explosion leads to driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up a cloud of gas and dust called a supernova remnant.

Different kinds of supernovae can be triggered in one of the two following ways: either turning off or suddenly turning on the production of energy through nuclear fusion. If an aging giant star fails to generate energy from the nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or a black hole, releasing gravitational potential energy that heats and expels the star’s outer layers. White dwarfs are subject to a different, much smaller type of thermonuclear explosion fuelled by hydrogen on their surfaces called a nova.

Those solitary stars with a mass below approximately nine solar masses, such as the sun itself, advance into white dwarfs without becoming supernovae ever. Supernovae can occur about once every 50 years in a galaxy the size of the Milky Way on an average. They enrich the interstellar medium with higher mass elements. The expanding shock waves can also trigger the formation of new stars.

Invention:

Since supernovae are somewhat rare events within a galaxy, regular monitorings of many galaxies are required to obtain a good sample of supernovae for analysis. But, supernovae in other galaxies cannot be predicted with any significant accuracy. So, when they are discovered, they are already in progress normally. Studying the peak luminosity and observing them is a pre requisite for studying and analyzing supernovae. Many astronomers have made significant contribution by discovering supernovae. They did this typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier pictures.

But, with the advent of computers, astronomers have started using computer-controlled telescopes and CCD’s for hunting supernovae. These modern technologies with the computers have proved to be a helping hand to the astronomers analyzing supernovae.

Types:

Brightest supernova taken by chandra telescope

Type 1a – lacks hydrogen

Type 1b – Non-ionized helium

Type 1c – Weak or no helium

Type IIP – Reaches a plateau in its light curve

Type IIL – displays a “linear” decrease in its light curve

A near-Earth supernova explosion resulting from the death of a star that occurs close enough to the earth to have clear effects on its biosphere.

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The reason for “Glittering Diamonds” in the sky

Posted on July 18, 2009 by

Twinkling star formation

“Twinkle Twinkle little star,

How I wonder what you are.”

I am sure you have wondered about the “little star”, but have you wondered why it twinkles like a “diamond” in the sky?? The main reason for this is earth’s atmospheric turbulence.

As you all know, earth is made up of 6 main layers of atmosphere- troposphere, stratosphere, mesosphere, thermosphere, ionosphere and exosphere. These layers vary in their density and temperature. The constantly changing atmosphere will cause turbulence in the atmosphere. As each turbulent layer is of different composition, they can be considered to be a different medium. So, when light from a distant star reaches the earth’s atmosphere it gets refracted by each medium. Thus, the glittering diamonds you perceive is nothing, but the conglomerated refractions that the rays are forced to undergo, when it passes through each layer of the earth’s atmosphere. The amount of refraction or scattering will depend on the temperature of the scattering medium. If the air is warm or hot, the molecules will be further apart and hence will cause lesser scattering than when the air is cool.

The fact that the earth’s atmosphere is the cause for the “twinkling” is proved by Hubble space telescope, which has been installed in the outer space, free from the hurdles of the earth’s atmosphere. This telescope is known to produce crystal clear images of the entire Universe.

Stars like sun, which are near the horizon don’t twinkle. This is because the amount of radiations from the sun is very high, that the scattering of a few rays doesn’t matter much.

Hipparchus classified stars according to the amount of magnitude, ranging from one to six, first being the brightest. Scientists came up with methods such as photometry to quantify this brightness factor.

Planets, on the other hand, do not twinkle and are seen as discs through the telescope. As they are nearer to the earth, the atmospheric fluctuations and turbulence does not have any effect on the rays coming from these planets, and hence, the absence of twinkling.

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