KUIPER BELT

                                                          KUIPER BELT






Starting in 1992, astronomers have become aware of a vast population of small bodies orbiting the sun beyond Neptune. There are at least 70,000 "trans-Neptunians" with diameters larger than 100 km in the radial zone extending outwards from the orbit of Neptune (at 30 AU) to 50 AU. Observations show that the trans-Neptunians are mostly confined within a thick band around the ecliptic, leading to the realization that they occupy a ring or belt surrounding the sun. This ring is generally referred to as the Kuiper Belt.

The Kuiper Belt holds significance for the study of the planetary system on at least two levels. First, it is likely that the Kuiper Belt objects are extremely primitive remnants from the early accretional phases of the solar system. The inner, dense parts of the pre-planetary disk condensed into the major planets, probably within a few millions to tens of millions of years. The outer parts were less dense, and accretion progressed slowly. Evidently, a great many small objects were formed. Second, it is widely believed that the Kuiper Belt is the source of the short-period comets. It acts as a reservoir for these bodies in the same way that the Oort Cloud acts as a reservoir for the long-period comets.

The study of the trans-Neptunians is a rapidly evolving field, with major observational and theoretical advances in the last few years. A partial list of relevant papers is included on this Web page. You can also find a Table of the known trans-Neptunians, the discovery images for 1992 QB1, and a blink sequence which shows how these objects are identified.



In 1950, Dutch astronomer Jan Oort proposed that certain comets come from a vast, extremely distant, spherical shell of icy bodies surrounding the solar system. This giant swarm of objects is now named the Oort Cloud, occupying space at a distance between 5,000 and 100,000 astronomical units. (One astronomical unit, or AU, is the mean distance of Earth from the sun: about 150 million km or 93 million miles.) The outer extent of the Oort Cloud is believed to be in the region of space where the sun's gravitational influence is weaker than the influence of nearby stars.

The Oort Cloud probably contains 0.1 to 2 trillion icy bodies in solar orbit. Occasionally, giant molecular clouds, stars passing nearby, or tidal interactions with the Milky Way's disc disturb the orbits of some of these bodies in the outer region of the Oort Cloud, causing the object to fall into the inner solar system as a so-called long-period comet. These comets have very large, eccentric orbits and take thousands of years to circle the sun. In recorded history, they are observed in the inner solar system only once.

In contrast, short-period comets take less than 200 years to orbit the sun and they travel approximately in the plane in which most of the planets orbit. They are presumed to come from a disc-shaped region beyond Neptune called the Kuiper Belt, named for astronomer Gerard Kuiper. (It is sometimes called the Edgeworth-Kuiper Belt, recognizing the independent and earlier discussion by Kenneth Edgeworth.) The objects in the Oort Cloud and in the Kuiper Belt are presumed to be remnants from the formation of the solar system about 4.6 billion years ago.
The Kuiper Belt extends from about 30 to 55 AU and is probably populated with hundreds of thousands of icy bodies larger than 100 km (62 miles) across and an estimated trillion or more comets.

Because KBOs are so distant, their sizes are difficult to measure. The calculated diameter of a KBO depends on assumptions about how reflective the object's surface is. With infrared observations by the Spitzer Space Telescope, most of the largest KBOs have known sizes.

In 1992, astronomers detected a faint speck of light from an object about 42 AU from the sun -- the first time a Kuiper Belt object (or KBO for short) had been sighted. More than 1,300 KBOs have been identified since 1992. (They are sometimes called Edgeworth-Kuiper Belt objects, and they are sometimes called transneptunian objects or TNOs for short.)

One of the most unusual KBOs is Haumea, which is a part of a collisional family orbiting the sun. The parent body, Haumea, apparently collided with another object that was roughly half its size. The impact blasted large icy chunks away and sent Haumea reeling, causing it to spin end-over-end every four hours. It spins so fast that it has pulled itself into the shape of a squashed American football. Haumea and two small moons -- Hi'iaka and Namaka -- make up the family.

In March 2004, a team of astronomers announced the discovery of a planet-like transneptunian object orbiting the sun at an extreme distance, in one of the coldest known regions of our solar system. The object (2003VB12), since named Sedna for an Inuit goddess who lives at the bottom of the frigid Arctic ocean, approaches the sun only briefly during its 10,500-year solar orbit. It never enters the Kuiper Belt, whose outer boundary region lies at about 55 AU -- instead, Sedna travels in a long, elliptical orbit between 76 and nearly 1,000 AU from the sun. Since Sedna's orbit takes it to such an extreme distance, its discoverers have suggested that it is the first observed body belonging to the inner Oort Cloud.

In July 2005, a team of scientists announced the discovery of a KBO that was initially thought to be about 10 percent larger than Pluto. The object, temporarily designated 2003UB313 and later named Eris, orbits the sun about once every 560 years, its distance varying from about 38 to 98 AU. (For comparison, Pluto travels from 29 to 49 AU in its solar orbit.) Eris has a small moon named Dysnomia. More recent measurements show it to be slightly smaller than Pluto.

The discovery of Eris -- orbiting the sun and similar in size to Pluto (which was then designated the ninth planet) -- forced astronomers to consider whether Eris should be classified as the tenth planet. Instead, in 2006, the International Astronomical Union created a new class of objects called dwarf planets, and placed Pluto, Eris and the asteroid Ceres in this category.

While no spacecraft has yet traveled to the Kuiper Belt, NASA's New Horizons spacecraft is scheduled to arrive at Pluto in 2015. The New Horizons mission team hopes to study one or more KBOs after its Pluto mission is complete.

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How the Kuiper Belt and Oort Cloud Got Their Names

Both distant regions are named for the astronomers who predicted their existence -- Gerard Kuiper and Jan Oort. Objects discovered in the Kuiper Belt get their names from diverse mythologies. Eris is named for the Greek goddess of discord and strife. Haumea is named for a Hawaiian goddess of fertility and childbirth. Comets from both regions are generally named for the person who discovered them.

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Significant Dates

• 1943: Astronomer Kenneth Edgeworth suggests that a reservoir of comets and larger bodies resides beyond the planets.
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• 1950: Astronomer Jan Oort theorizes that a vast population of comets may exist in a huge cloud on the distant edges of our solar system.
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• 1951: Astronomer Gerard Kuiper predicts the existence of a belt of icy objects just beyond the orbit of Neptune.
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• 1992: After five years of searching, astronomers David Jewitt and Jane Luu discover the first KBO, 1992QB1.
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• 2002: Scientists using the 48-inch Oschin telescope at Palomar Observatory find Quaoar, the first large KBO hundreds of kilometers in diameter. This object was photographed in 1980, but was not noticed in those images.
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• 2004: Astronomers using the 48-inch Oschin telescope announce the discovery of Sedna (2003VB12).
• 2005:Astronomers announce the discovery of 2003UB313. This object, later named Eris, is slightly larger than Pluto.
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• 2008: The Kuiper Belt object provisionally known as 2005FY9 ("Easterbunny") is recognized in July as a dwarf planet and named Makemake (pronounced MAHkeh-MAHkeh) after the Polynesian (Rapa Nui) creation god. In September, 2003EL61 ("Santa") was designated a dwarf planet and given the name Haumea after the Hawaiian goddess of fertility and childbirth.

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BLACK HOLE

                                                                BLACK HOLES 





Black holes are some of the strangest and most fascinating objects found in outer space. They are objects of extreme density, with such strong gravitational attraction that even light cannot escape from their grasp if it comes near enough.

Stellar black holes — small but deadly

When a star burns through the last of its fuel, it may find itself collapsing. For smaller stars, up to about three times the sun's mass, the new core will be a neutron star or a white dwarf. But when a larger star collapses, it continues to fall in on itself to create a stellar black hole.

Black holes formed by the collapse of individual stars are (relatively) small, but incredibly dense. Such an object packs three times or more the mass of the sun into a city-sized range. This leads to a crazy amount of gravitational force pulling on objects around it. Black holes consume the dust and gas from the galaxy around them, growing in size.

Supermassive black holes — the birth of giants

Small black holes populate the universe, but their cousins, supermassive black holes, dominate. Supermassive black holes are millions or even billions of times as massive as the sun, but have a radius similar to that of Earth's closest star. Such black holes are thought to lie at the center of pretty much every galaxy, including the Milky Way.

Scientists aren't certain how such large black holes spawn. Once they've formed, they can easily gather mass from the dust and gas around them, material that is plentiful in the center of galaxies, allowing them to grow to enormous sizes. 

Supermassive may be the result of hundreds or thousands of tiny black holes that merge together. Large gas clouds could also be responsible, collapsing together and rapidly accreting mass. A third option is the collapse of a stellar cluster, a group of stars all falling together.

Intermediate black holes – stuck in the middle

Scientists once thought black holes came in only small and large sizes, but recent research has revealed the possibility for the existence of midsize, or intermediate, black holes. Such bodies could form when stars in a cluster collide in a chain reaction. Several of these forming in the same region could eventually fall together in the center of a galaxy and create a supermassive black hole. 

Black hole theory — How they tick

Black holes are incredibly massive, but cover only a small region. Because of the relationship between mass and gravity, this means they have an extremely powerful gravitational force. Virtually nothing can escape from them — under classical physics, even light is trapped by a black hole.

Such a strong pull creates an observational problem when it comes to black holes — scientists can't "see" them the way they can see stars and other objects in space. Instead, scientists must rely on the radiation that is emitted as dust and gas are drawn into the dense creatures. Supermassive black holes, lying in the center of a galaxy, may find themselves shrouded by the dust and gas thick around them, which can block the tell-tale emissions.

Sometimes as matter is drawn toward a black hole, it ricochets off of the event horizon and is hurled outward, rather than being tugged into the maw. Bright jets of material traveling at near-relativistic speeds are created. Although the black hole itself remains unseen, these powerful jets can be viewed from great distances.

Black holes have three "layers" — the outer and inner event horizon and the singularity.

The event horizon of a black hole is the boundary around the mouth of the black hole where light loses its ability to escape. Once a particle crosses the event horizon, it cannot leave. Gravity is constant across the event horizon.

The inner region of a black hole, where its mass lies, is known as its singularity, the single point in space-time where the mass of the black hole is concentrated.

Under the classical mechanics of physics, nothing can escape from a black hole. However, things shift slightly when quantum mechanics are added to the equation. Under quantum mechanics, for every particle, there is an antiparticle, a particle with the same mass and opposite electric charge. When they meet, particle-antiparticle pairs can annihilate one another.

If a particle-antiparticle pair is created just beyond the reach of the event horizon of a black hole, it is possible to have one drawn into the black hole itself while the other is ejected. The result is that the event horizon of the black hole has been reduced and black holes can decay, a process that is rejected under classical mechanics.

Scientists are still working to understand the equations by which black holes function.

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INTERESTING FACTS ON MILKY WAY GALAXY

             INTERESTING FACTS ON MILKY WAY GALAXY

1. It’s warped.

The Milky Way is a disk about 120,000 light years across (see the Guide to Space article on the diameter of the Milky Way for more), with a central bulge that has a diameter of 12,000 light years. The disk is far from perfectly flat though, as can be seen in the picture below. What warped it? Two of the galaxy’s neighbors – the Large and Small Magellanic clouds – have been pulling on the dark matter in the Milky Way like in a game of galactic tug-of-war. The tugging sets up a sort of oscillating frequency that pulls on the hydrogen gas (of which the Milky Way has lots of). Here’s a more in-depth article on Universe Today about How the Milky Way got its Warp.

The Milky Way has a halo of dark matter that makes up over 90% of its mass. Yes, 90%. That means that all of what we can see (with the naked eye or telescopes) makes up less than 10% of the mass of the Milky Way. Now, it doesn’t have a halo like those old cartoon characters that die, sprout wings and play a harp in the clouds. The halo is actually invisible, though we know it exists by running simulations of what the Milky Way would look like and how fast stars inside the galaxy’s disk orbit the center. The heavier it is, the faster they should be orbiting. If you assume that the galaxy is made up only of matter that we can see, then you get a rotation rate for the stars that is well below what it should be, so the rest is made up of what is elusively called “dark matter,” or matter that only interacts gravitationally (so far as we know) with “normal matter”.

2. It has a halo, but you can’t directly see it.

The Milky Way has a halo of dark matter that makes up over 90% of its mass. Yes, 90%. That means that all of what we can see (with the naked eye or telescopes) makes up less than 10% of the mass of the Milky Way. Now, it doesn’t have a halo like those old cartoon characters that die, sprout wings and play a harp in the clouds. The halo is actually invisible, though we know it exists by running simulations of what the Milky Way would look like and how fast stars inside the galaxy’s disk orbit the center. The heavier it is, the faster they should be orbiting. If you assume that the galaxy is made up only of matter that we can see, then you get a rotation rate for the stars that is well below what it should be, so the rest is made up of what is elusively called “dark matter,” or matter that only interacts gravitationally (so far as we know) with “normal matter”.

3. It has over 200 billion stars

As galaxies go, the Milky Way is a middleweight. The largest galaxy known, IC 1101, has over 100 trillion stars, and other large galaxies can have more than a trillion stars. Smaller galaxies like the aforementioned Large Magellanic Cloud, have about 10 billion stars. The Milky Way has between 200-400 billion stars, but when you look up into the night sky the most you can see from any one point on the Earth is about 2,500. We aren’t stuck with this many stars forever, though, because the Milky Way is constantly losing stars – through supernovae – and producing stars, netting about seven stars per year.

4. It’s really dusty and gassy.

You may not think so by looking at it, but the Milky Way is full of dust and gas. And when I say full of dust, I mean that we can only see out about 6,000 light years into the disk of our own galaxy in the visible spectrum, and the galaxy is about 100,000 light years across! The dust and gas makes up a whopping 10-15% of the “normal matter” in the galaxy, with the remainder being stars. The thickness of the dust deflects visible light, as is explainedhere, but infrared light can pass through the dust, which makes infrared telescopes like the Spitzer Space Telescope extremely valuable tools in mapping and studying the galaxy. Spitzer can peer through the dust to give us extraordinarily clear views of what is going on at the heart of the galaxy and in star-forming regions.

5. It’s made up of other galaxies.

The Milky Way wasn’t always as it is today, a beautiful barred spiral. It became its current size and shape by eating up other galaxies. It’s still doing so today – the Canis Major Dwarf Galaxy is the closest galaxy to the Milky Way because its stars are currently being added to the Milky Way’s disk, and our galaxy has consumed others in its long history, such as the Sagittarius Dwarf Galaxy.

6. Every picture you’ve seen of the Milky Way from above is either another galaxy or an artist’s interpretation.

We can’t take a picture of the Milky Way from above (yet) because we are inside the galactic disk, about 26,000 light years from the galactic center. This means that any pretty pictures you see of a spiral galaxy with elegant arms that is supposedly the Milky Way is either a picture of another spiral galaxy, or the rendering of a talented artist. Imaging the Milky Way from above is a long, long way off; however, this doesn’t mean that we can’t takebreathtaking images of the Milky Way from our vantage point!

7. There is a black hole at the center.

Most galaxies have a supermassive black hole at the center. Ours is no exception. The center of our galaxy is called Sagittarius A* (pronounced “A-star”), and it houses a black hole with a mass of 40,000 Suns that is 14 million miles across (about the size of Mercury’s orbit). But this is just the black hole itself. All of the mass trying to get into the black hole – called the accretion disk – forms a disk that has a mass of 4 million Suns, and would fit inside the orbit of the Earth. Though like other black holes, Sgr A* tries to consume anything that happens to be nearby, star formation has been detected near this black hole behemoth.

8. It’s almost as old as the Universe itself.

The most current estimate for the age of the Universe is about 13.7 billion years. Our Milky Way has been around for about 13.6 billion of those years, give or take 800 million years. The oldest stars in our the Milky Way are found in globular clusters, and the age of the galaxy is determined by taking the age of these stars, and then extrapolating the age of what preceded them. Though some of the constituents of the Milky Way have been around for a long time, the disk and bulge themselves didn’t form until about 10-12 billion years ago, and the bulge may have formed earlier than the rest of the galaxy.

9. It’s part of the Virgo Supercluster, a grouping of galaxies within 150 million light years.

As big as it is, the Milky Way is part of an even bigger structure called a supercluster. Superclusters are groupings of galaxies on very large scales (100s of millions of light years). In between these superclusters are large voids of space where any space traveler would encounter very little in the way of galaxies or matter. Our close neighbors include the Large and Small Magellanic Clouds, and the Andromeda Galaxy (the closest spiral galaxy to the Milky Way), and along with about 30 other galaxies this group of galaxies makes up what is called the Local Group. But as you get further on out, on the scale of hundreds of millions of light years, the Milky Way can be seen to be just a small part of a large grouping of galaxies 150 million light years in diameter called the Virgo Supercluster.

10. It’s on the move

The Milky Way, along with everything else, is moving through space, and puts to shame anything from everyday life that one could compare its speed to. The Earth moves around the Sun, the Sun around the Milky Way, and the Milky Way is part of the Local Group, which is moving relative to the Cosmic Microwave Background radiation – the radiation left over from the Big Bang, which is a convenient reference point to use when determining the velocity of things in the Universe. The Local Group is calculated to move relative to the CMB at about 600 km/s (2,200,000 km/h), which is pretty darn fast!

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INTERESTING FACTS ABOUT PLANETS

                                INTERESTING FACTS ABOUT PLANETS

1. Mercury is hot but it might have ice
Mercury is the closest planet to the Sun and is one of the hottest planets in the Solar System, but it may contain ice. Mercury slowly rotates around the Sun, exposing all of its sides to the Sun’s relentless rays, so it seems hard to imagine where the ice could remain solid. Scientists speculate that the ice is located in craters near the poles of the planet. These craters are deep enough and close enough to the top of the planet to keep the ice out of direct sunlight.

2. There’s definitely water on Mars (ice, anyway)
Mars has always captivated the imagination of writers and scientists alike. Ever since canals and canyons were discovered on the planet’s surface, the search for water on Mars has been ongoing. You may be surprised to know that scientists have discovered water on Mars, although it does not come in liquid form. This discovery was first detected by the NASA’s spacecraft Odyssey. In 2008, the presence of water on Mars was confirmed by the NASA’s Phoenix. The Phoenix Lander collected samples of what was later determined to be water ice. The patch that the Phoenix Lander collected its samples from was termed the “Snow Queen” by scientists.

3. Venus is actually the hottest planet in the Solar System
Even though Mercury is the closest planet to the Sun, Venus is the hottest planet in our Solar System. Venus’s thick atmosphere traps the heat from the Sun, a kind of greenhouse effect, and retains it. Sulfuric acid and carbon dioxide in the atmosphere are compounds that help trap the heat. The temperature on Venus is about 465°C (870°F). Venus’s extreme temperatures and toxic atmosphere make it an unlikely place for the existence of life.

4. Jupiter’s big. No, really really big. And massive too.
Jupiter has the most mass of any planet in the Solar System. You may be wondering exactly how massive this planet is. Not only is Jupiter’s mass 318 times the mass of the Earth, but it is also two and a half times the mass of all the planets in the entire Solar System. Even though the planet is massive, it has a density lower than Earth’s. This causes Jupiter to have a gravity approximately two and a half times greater than Earth’s gravity.

5. And yet, Jupiter is the fastest rotating planet
Despite Jupiter’s large mass, it is the fastest planet to complete a full axial rotation. It takes just under ten hours for the planet to do a full rotation. As a result of its extreme speed, Jupiter has actually flattened at both ends and expanded in the middle like a ball that is being compressed between someone’s hands.

6. The Earth’s magnetic field protects it
Earth has a magnetic field with magnetic poles close to the North and South geographic poles. This magnetic field is so strong that its influence reaches thousands of kilometers from the surface of the Earth to the magnetosphere. The magnetosphere is one of the reasons why life can exist on Earth. It acts as a kind of shield, diverting harmful radiation from the Sun away from the Earth where it would severely damage, if not destroy, life. Scientists theorize that the currents of the Earth’s liquid outer core cause this magnetic field.

7. Our view of Saturn’s rings are constantly changing
Saturn is famous for its distinctive rings that were first seen by Galileo in the beginning of the 17th century. Saturn’s rings, which can be seen with the unaided eye from Earth, sometimes disappear from sight. Every 14 to 15 years in its orbit around the Sun, Saturn turns a specific way. At that angle, the planet’s rings become so thin viewed from Earth that they seem to simply disappear. Here are 10 facts about Saturn.

8. Uranus is flipped over on its side
Uranus is the only planet to rotate on its side; it rotational tilt is very strong – approximately 97.9°. Uranus’ unique tilt results in extreme seasonal changes. The planet goes through seasonal cycles of 21 years each. There are 21 years of a normal night and day cycle on Uranus, which is followed by 21 years of day in the Northern Hemisphere. After another normal 21-year period, there are 21 years of night in the Northern Hemisphere. Then the planet begins its cycle all over again.

9. And Uranus is the coldest place in the Solar System
Uranus, the second furthest planet from the Sun, is the coldest planet in our Solar System. That distinction used to belong to Pluto , which was the ninth planet until it was reduced to the status of dwarf planet. Uranus’ temperature can drop to -224°C, which is less than -371°F. Those kind of drastically cold temperatures seem unimaginable. Even though it is closer to the Sun than Neptune, it is colder than the final planet. Uranus’ extreme temperature is a result of its core. Unlike the other planets, Uranus actually releases less heat than it absorbs from the Sun because its core is much cooler than the cores of the other planets.

10. Neptune has the fastest winds of any of the eight planets. 
The winds on Neptune reach at least 2,100 km per hour and are capable of ripping buildings to shreds. Considering the strongest hurricanes, such as Hurricane Andrew, only have winds exceeding 251 km per hour, Neptune’s winds are incredibly powerful. Scientists are not certain how the planet’s winds can be that fast, but some believe it is due to a combination of frigid temperatures and Neptune’s atmosphere.

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WANT TO BECOME AN ASTRONAUT

                                    WANT TO BECOME AN ASTRONAUT






Astronaut Responsibilities 

Astronauts are involved in all aspects of assembly and on-orbit operations of the ISS  This includes extravehicular activities (EVA), robotics operations using the remote manipulator system, experiment operations, and onboard maintenance tasks.  Astronauts are required to have a detailed knowledge of the ISS systems, as well as detailed knowledge of the operational characteristics, mission requirements and objectives, and supporting systems and equipment for each experiment on their assigned missions. 
Long-duration missions aboard the ISS generally last from 3 to 6 months.

  Training for long duration missions is very arduous and takes approximately 2 to 3 years.  This training requires extensive travel, including long periods away in other countries training with our International partners.  Travel to and from the ISS will be aboard the Russian Soyuz vehicle.  Consequently, astronauts must meet the Soyuz size requirements, as indicated below.

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Basic Qualification Requirements 

Applicant must meet the following minimum requirements before submitting an application.
Astronaut Candidate (Non-Piloting background)

1. Bachelor’s degree from an accredited institution in engineering, biological science, physical science, or mathematics.  Quality of academic preparation is important. 
2. Degree must be followed by at least 3 years of related, progressively responsible, professional experience or at least 1,000 pilot-in-command time in jet aircraft.  An advanced degree is desirable and may be substituted for experience as follows: master’s degree = 1 year of experience, doctoral degree = 3 years of experience.  Teaching experience, including experience at the K - 12 levels, is considered to be qualifying experience for the Astronaut Candidate position; therefore, educators are encouraged to apply.
3. Ability to pass the NASA long-duration space flight physical, which includes the following specific requirements:
   
   Distant and near visual acuity: Must be correctable to 20/20, each eye
   
   The refractive surgical procedures of the eye, PRK and LASIK, are allowed, providing at least 1 year has passed since the date of the procedure with no permanent adverse after effects.  For those applicants under final consideration, an operative report on the surgical procedure will be requested. 

Blood pressure not to exceed 140/90 measured in a sitting position

Standing height between 62 and 75 inches

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Notes on Academic Requirements 

Applicants for the Astronaut Candidate Program must meet the basic education requirements for NASA engineering and scientific positions - specifically: successful completion of standard professional curriculum in an accredited college or university leading to at least a bachelor's degree with major study in an appropriate field of engineering, biological science, physical science, or mathematics. The following degree fields, while related to engineering and the sciences, are not considered qualifying:

*- Degrees in Technology (Engineering Technology, Aviation Technology, Medical Technology, etc.)
*- Degrees in Psychology (except for Clinical Psychology, Physiological Psychology, or Experimental Psychology which are qualifying).
*- Degrees in Nursing.
*- Degrees in Exercise Physiology or similar fields
*- Degrees in Social Sciences (Geography, Anthropology, Archaeology, etc.).
*- Degrees in Aviation, Aviation Management, or similar fields.

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Citizenship Requirements 

Applicants for the Astronaut Candidate Program must be citizens of the United States, applicants with valid U.S. dual-citizenship are also eligible.

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Application Procedures  

• Civilian
  Applications can only be submitted through the Office of Personnel Management’s USAJOBS site   www.usajobs.gov
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• Active Duty Military 
• Active duty military personnel must submit applications through the Office of Personnel Management’s USA JOBS Web site http://www.usajobs.gov and to their respective military service. Contact your military service for additional application procedures.
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Selection

 Following the preliminary screening of applications, additional information may be requested from some applicants, and individuals listed in the application as supervisors and references may be contacted.  Applicants who are being considered as finalists for interview may be required to obtain a flight physical. 

A week-long process of personal interviews, medical screening, and orientation will be required for both civilian and military applicants under final consideration.  Further interviews and a complete medical evaluation will be conducted prior to selection.  Once final selections have been made, all applicants will be notified of the outcome of the process.  Complete background investigations will be performed on those selected.

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EFFECTS OF COSMIC RAYS

                                                      EFFECTS OF COSMIC RAYS

EFFECT ON EARTH ENVIRONMENT :

        

EFFECT ON HUMAN :

  



Effects

Changes in atmospheric chemistry

Cosmic rays ionize the nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. One of the reactions results in ozone depletion. Cosmic rays are also responsible for the continuous production of a number of unstable isotopes in the Earth’s atmosphere, such as carbon-14, via the reaction:

n + ¹⁴N → p + ¹⁴C

Cosmic rays kept the level of carbon-14 ^[17] in the atmosphere roughly constant (70 tons) for at least the past 100,000 years, until the beginning of above-ground nuclear weapons testing in the early 1950s. This is an important fact used in radiocarbon dating used in archaeology.

Reaction products of primary cosmic rays, radioisotope half-lifetime, and production reaction.

• Tritium (12.3 years): 14N(n, 3H)12C (Spallation)
• Beryllium-7 (53.3 days)
• Beryllium-10 (1.39 million years): 14N(n,p α)10Be (Spallation)
• Carbon-14 (5730 years): 14N(n, p)14C (Neutron activation)
• Sodium-22 (2.6 years)
• Sodium-24 (15 hours)
• Magnesium-28 (20.9 hours)
• Silicon-31 (2.6 hours)
• Silicon-32 (101 years)
• Phosphorus-32 (14.3 days)
• Sulfur-35 (87.5 days)
• Sulfur-38 (2.8 hours)
• Chlorine-34 m (32 minutes)
• Chlorine-36 (300,000 years)
• Chlorine-38 (37.2 minutes)
• Chlorine-39 (56 minutes)
• Argon-39 (269 years)
• Krypton-85 (10.7 years)

Role in ambient radiation

Cosmic rays constitute a fraction of the annual radiation exposure of human beings on the Earth, averaging 0.39 mSv out of a total of 3 mSv per year (13% of total background) for the Earth's population. However, the background due to cosmic rays can vary from 0.3 mSv/year at sea level to 1.0 mSv per year in high-altitude cities, which would raise cosmic radiation exposure to a quarter of the total background. Airline crews flying long distance high-altitude routes can be exposed to 2.2 mSv of extra radiation each year due to cosmic rays, which nearly doubles their total ionizing radiation exposure. The following table compares cosmic radiation doses to other sources of background radiation:

Average annual radiation exposure (millisievert)

Radiation		UNSCEAR		Princeton	Wa State	MEXT
Type	Source	World average	Typical range	USA	USA	Japan	remark
Natural	Air	1.26	0.2-10.0a	2.29	2.00	0.40	mainly from Radon, (a)depend on indoor accumulation of radon gas
	Internal	0.29	0.2-1.0b	0.16	0.40	0.40	mainly from food (K-40, C-14, etc.) (b)Depend on diets
	Terrestrial	0.48	0.3-1.0c	0.19	0.29	0.40	(c)depend on soil and building material
	Cosmic	0.39	0.3-1.0d	0.31	0.26	0.30	(d)from sea level to high elevation
	sub total	2.40	1.0-13.0	2.95	2.95	1.50
Man made	Medical	0.60	0.03-2.0	3.00	0.53	2.30
	Fallout	0.007	0 - 1+	-	-	0.01	peak at 1963 and spike at 1986. still high near test and accident sites. US; Fallout is included in others
	others	0.0052	0-20	0.25	0.13	0.001	average occupational exposure 0.7mSv, mining workers are high, population near Nuclear plant 0.02mSv
	sub total	0.6	0 to tens	3.25	0.66	2.311
Total		3.00	0 to tens	6.20	3.61	3.81

Effect on electronics

Cosmic rays have sufficient energy to alter the states of elements in electronic integrated circuits, causing transient errors to occur, such as corrupted data in electronic memory devices, or incorrect performance of CPUs, often referred to as "soft errors" (not to be confused with software errors caused by programming mistakes/bugs).

 This has been a problem in extremely high-altitude electronics, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well. Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month.

To alleviate this problem, the Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event.

Cosmic rays are suspected as a possible cause of an in-flight incident in 2008 where an Airbus A330 airliner of Qantas twice plunged hundreds of feet after an unexplained malfunction in its flight control system. Many passengers and crew members were injured, some seriously. After this incident, the accident investigators determined that the airliner's flight control system had received a data spike that could not be explained, and that all systems were in perfect working order. This has prompted a software upgrade to all A330 and A340 airliners, worldwide, so that any data spikes in this system are filtered out electronically.

Significance to space travel

Galactic cosmic rays are one of the most important barriers standing in the way of plans for interplanetary travel by crewed spacecraft. Cosmic rays also pose a threat to electronics placed aboard outgoing probes. In 2010, a malfunction aboard the Voyager 2 space probe was credited to a single flipped bit, probably caused by a cosmic ray.

Role in lightning

Cosmic rays have been implicated in the triggering of electrical breakdown in lightning. It has been proposed that essentially all lightning is triggered through a relativistic process, "runaway breakdown", seeded by cosmic ray secondaries. Subsequent development of the lightning discharge then occurs through "conventional breakdown" mechanisms.

Role in climate change

A role of cosmic rays directly or via solar-induced modulations in climate change was suggested by Edward P. Ney in 1959 and by Robert Dickinson in 1975. In recent years, the idea has been revived most notably by Henrik Svensmark; the most recent IPCC study disputed the mechanism,^[39] while the most comprehensive review of the topic to date states: "evidence for the cosmic ray forcing is increasing as is the understanding of its physical principles."

Suggested mechanisms

Henrik Svensmark et al. have argued that solar variations modulate the cosmic ray signal seen at the Earth and that this would affect cloud formation and hence climate. Cosmic rays have been experimentally determined capable of producing ultra-small aerosol particles, orders of magnitude smaller than cloud condensation nuclei (CCN).

According to a report about an ongoing CERN CLOUD research project to detect any Cosmic ray forcing is challenging since on wide spread time scales changes in the Sun’s magnetic activity, Earth’s magnetic field, and the galactic environment must be taken into account. Empirically, increased galactic cosmic ray (GCR) flux seem to be associated with a cooler climate, a southerly shift of the ITCZ (Inter Tropical Convergence Zone) and a weakening of monsoon rainfalls and vice versa.

Claims have been made of identification of GCR climate signals in atmospheric parameters such as high latitude precipitation (Todd & Kniveton), and Svensmark's annual cloud cover variations, which were said to be correlated to GCR variation. Various proposals have been made for the mechanism by which cosmic rays might affect clouds, including ion mediated nucleation, and indirect effects on current flow density in the global electric circuit (see Tinsley 2000, and F. Yu 1999). 

Other studies refer to the formation of relatively highly charged aerosols and cloud droplets at cloud boundaries, with an indirect effect on ice particle formation and altering aerosol interaction with cloud droplets. Kirkby (2009) reviews developments and describes further cloud nucleation mechanisms that appear energetically favorable and depend on GCRs.,

Geochemical and astrophysical evidence

Nir Shaviv has argued that climate signals on geological time scales are attributable to changing positions of the galactic spiral arms of the Milky Way Galaxy, and that cosmic ray flux variability is the dominant "climate driver" over these time periods. Nir Shaviv and Jan Veizer in 2003 argue, that in contrast to a carbon based scenario, the model and proxy based estimates of atmospheric CO₂ levels especially for the early Phanerozoic (see diagrams) do not show correlation with the paleoclimate picture that emerged from geological criteria, while cosmic ray flux would do.

The 2007 IPCC reports, however, strongly attribute a major role of anthropogenic carbon dioxide in the ongoing global warming, but as "different climate changes in the past had different causes" a driving role of carbon dioxide in the geological past is neither focus of the IPCC nor purported. A comprehensive study of different research institutes was published 2007 by Scherer et al. in Space Science Reviews 2007. The study combines geochemical evidence both on temperature, cosmic rays influence and as well astrophysical deliberations suggesting a major role in climate variability over different geological time scales. Proxy data of CRF influence comprise among others isotopic evidence in sediments on the Earth and as well changes in (iron) meteorites.


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