1.
Caltech Submillimeter Observatory
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The Caltech Submillimeter Observatory is a 10. 4-meter diameter submillimeter wavelength telescope situated alongside the 15-meter James Clerk Maxwell Telescope at Mauna Kea Observatories. It is engaged in astronomy, of the terahertz radiation band. The telescope closed on September 18,2015, the telescope is set to be decommissioned in the near future as part of the Mauna Kea Comprehensive Management Plan. The CSO and JCMT were combined to form the first submillimeter interferometer, the success of this experiment was important in pushing ahead the construction of the Submillimeter Array and the Atacama Large Millimeter Array interferometers. On April 30,2009, Caltech announced plans to decommission the CSO, the plans call for CSO to be dismantled, beginning in 2016, with its site returned to a natural state by 2018
2.
Mauna Kea Observatories
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The facilities are located in a 525-acre special land use zone known as the Astronomy Precinct, which is located within the 11, 228-acre Mauna Kea Science Reserve. The Astronomy Precinct was established in 1967 and is located on land protected by the Historical Preservation Act for its significance to Hawaiian culture. After studying photos for NASAs Apollo program that contained greater detail than any ground based telescope, while he first began looking in Chile, he also made the decision to perform tests in the Hawaiian Islands. Tests on Mauis Haleakalā were promising, but the mountain was too low in the inversion layer, on the Big Island of Hawaiʻi, Mauna Kea is considered the highest island mountain in the world. While the summit is covered with snow, the air is extremely dry. Kuiper began looking into the possibility of an observatory on Mauna Kea, after testing, he discovered the low humidity was perfect for infrared signals. He persuaded Hawaiʻi Governor John A. Burns to bulldoze a road to the summit where he built a small telescope on Puʻu Poliʻahu. The peak was the second highest on the mountain with the highest peak being holy ground, next, Kuiper tried enlisting NASA to fund a larger facility with a large telescope, housing and other needed structures. NASA, in turn decided to make the open to competition. Professor of physics, John Jefferies of the University of Hawaii placed a bid on behalf of the university, Jefferies had gained his reputation through observations at Sacramento Peak Observatory. The proposal was for a telescope to serve both the needs of NASA and the university. Kuiper would abandon his site over the competition and begin work in Arizona on a different NASA project, after considerable testing by Jefferies team, the best locations were determined to be near the summit at the top of the cinder cones. Testing also determined Mauna Kea to be superb for nighttime viewing due to many factors, including the air, constant trade winds. Jefferies would build a 2.24 meter telescope with the State of Hawaiʻi agreeing to build a reliable, building began in 1967 and first light was seen in 1970. Other groups began requesting subleases on the newly accessible mountaintop, by 1970, two 24 in telescopes had been constructed by the United States Air Force and Lowell Observatory. In 1973, Canada and France agreed to build the 3.6 m CFHT on Mauna Kea, however, local organizations started to raise concerns about the environmental impact of the observatory. This led the Department of Land and Natural Resources to prepare a management plan, drafted in 1977. In January 1982, the University of Hawaiʻi Board of Regents approved a plan to support the development of scientific facilities at the site
3.
American and British English spelling differences
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Many of the differences between American and British English date back to a time when spelling standards had not yet developed. For instance, some spellings seen as American today were once used in Britain. But English-language spelling reform has rarely been adopted otherwise, and thus modern English orthography varies somewhat between countries and is far from phonemic in any country, in the early 18th century, English spelling was inconsistent. These differences became noticeable after the publishing of influential dictionaries, todays British English spellings mostly follow Johnsons A Dictionary of the English Language, while many American English spellings follow Websters An American Dictionary of the English Language. Webster was a proponent of English spelling reform for reasons both philological and nationalistic, in A Companion to the American Revolution, John Algeo notes, it is often assumed that characteristically American spellings were invented by Noah Webster. He was very influential in popularizing certain spellings in America, rather he chose already existing options such as center, color and check for the simplicity, analogy or etymology. William Shakespeares first folios, for example, used spellings like center and color as much as centre, Webster did attempt to introduce some reformed spellings, as did the Simplified Spelling Board in the early 20th century, but most were not adopted. In Britain, the influence of those who preferred the Norman spellings of words proved to be decisive, later spelling adjustments in the United Kingdom had little effect on todays American spellings and vice versa. For the most part, the systems of most Commonwealth countries. Australian spelling has also strayed slightly from British spelling, with some American spellings incorporated as standard, New Zealand spelling is almost identical to British spelling, except in the word fiord. There is also an increasing use of macrons in words that originated in Māori, most words ending in an unstressed -our in British English end in -or in American English. Wherever the vowel is unreduced in pronunciation, e. g. contour, velour, paramour and troubadour the spelling is the same everywhere, most words of this kind came from Latin, where the ending was spelled -or. They were first adopted into English from early Old French, after the Norman conquest of England, the ending became -our to match the Old French spelling. The -our ending was not only used in new English borrowings, however, -or was still sometimes found, and the first three folios of Shakespeares plays used both spellings before they were standardised to -our in the Fourth Folio of 1685. After the Renaissance, new borrowings from Latin were taken up with their original -or ending, Websters 1828 dictionary had only -or and is given much of the credit for the adoption of this form in the United States. Johnson, unlike Webster, was not an advocate of spelling reform and he preferred French over Latin spellings because, as he put it, the French generally supplied us. In Jeffersons original draft it is spelled honour, Honor and honour were equally frequent in Britain until the 17th century, honor still is, in the UK, the usual spelling as a persons name and appears in Honor Oak, a district of London. In derivatives and inflected forms of the words, British usage depends on the nature of the suffix used
4.
Observational astronomy
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It is the practice of observing celestial objects by using telescopes and other astronomical apparatus. As a science, the study of astronomy is somewhat hindered in that direct experiments with the properties of the distant universe are not possible, however, this is partly compensated by the fact that astronomers have a vast number of visible examples of stellar phenomena that can be examined. This allows for data to be plotted on graphs. Nearby examples of phenomena, such as variable stars, can then be used to infer the behavior of more distant representatives. Those distant yardsticks can then be employed to measure other phenomena in that neighborhood, galileo Galilei turned a telescope to the heavens and recorded what he saw. Since that time, observational astronomy has made steady advances with each improvement in telescope technology, visible-light astronomy falls in the middle of this range. Infrared astronomy deals with the detection and analysis of infrared radiation, the most common tool is the reflecting telescope but with a detector sensitive to infrared wavelengths. Space telescopes are used at wavelengths where the atmosphere is opaque. Radio astronomy detects radiation of millimetre to decametre wavelength, the receivers are similar to those used in radio broadcast transmission but much more sensitive. High-energy astronomy includes X-ray astronomy, gamma-ray astronomy, and extreme UV astronomy, in addition to using electromagnetic radiation, modern astrophysicists can also make observations using neutrinos, cosmic rays or gravitational waves. Observing a source using multiple methods is known as multi-messenger astronomy, optical and radio astronomy can be performed with ground-based observatories, because the atmosphere is relatively transparent at the wavelengths being detected. Observatories are usually located at high altitudes so as to minimise the absorption and distortion caused by the Earths atmosphere, some wavelengths of infrared light are heavily absorbed by water vapor, so many infrared observatories are located in dry places at high altitude, or in space. Powerful gamma rays can, however be detected by the air showers they produce. For much of the history of astronomy, almost all observation was performed in the visual spectrum with optical telescopes. The seeing conditions depend on the turbulence and thermal variations in the air, locations that are frequently cloudy or suffer from atmospheric turbulence limit the resolution of observations. Likewise the presence of the full Moon can brighten up the sky with scattered light, for observation purposes, the optimal location for an optical telescope is undoubtedly in outer space. There the telescope can make observations without being affected by the atmosphere, however, at present it remains costly to lift telescopes into orbit. Thus the next best locations are certain mountain peaks that have a number of cloudless days
5.
Terahertz radiation
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Photon energy in THz regime is less than band-gap of nonmetallic materials and thus THz beam can traverse through such materials. The transmitted THz beam is used for material characterization, layer inspection, terahertz radiation falls in between infrared radiation and microwave radiation in the electromagnetic spectrum, and it shares some properties with each of these. Like infrared and microwave radiation, terahertz radiation travels in a line of sight and is non-ionizing, like microwave radiation, terahertz radiation can penetrate a wide variety of non-conducting materials. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, plastic, the penetration depth is typically less than that of microwave radiation. Terahertz radiation has limited penetration through fog and clouds and cannot penetrate liquid water or metal, THz is not ionizing yet can penetrate some distance through body tissue, so it is of interest as a replacement for medical X-rays. Due to its wavelength, images made using THz are low resolution. However, at distances of ~10 meters the band may still allow many useful applications in imaging and construction of high bandwidth wireless networking systems, terahertz radiation is emitted as part of the black-body radiation from anything with temperatures greater than about 10 kelvin. The opacity of the Earths atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, and electronic oscillators based on resonant tunneling diodes have been shown to operate up to 700 GHz. There have also been solid-state sources of millimeter and submillimeter waves for many years, AB Millimeter in Paris, for instance, produces a system that covers the entire range from 8 GHz to 1000 GHz with solid state sources and detectors. Nowadays, most time-domain work is done via ultrafast lasers, in mid-2007, scientists at the U. S. The group was led by Ulrich Welp of Argonnes Materials Science Division, the device uses high-temperature superconducting crystals, grown at the University of Tsukuba in Japan. This alternating current induces an electromagnetic field, even a small voltage can induce frequencies in the terahertz range, according to Welp. In 2008, engineers at Harvard University achieved room temperature emission of several hundred nanowatts of coherent terahertz radiation using a semiconductor source, THz radiation was generated by nonlinear mixing of two modes in a mid-infrared quantum cascade laser. Previous sources had required cryogenic cooling, which limited their use in everyday applications. In 2009, it was discovered that the act of unpeeling adhesive tape generates non-polarized terahertz radiation, with a peak at 2 THz. In 2011, Japanese electronic parts maker Rohm and a team at Osaka University produced a chip capable of transmitting 1.5 Gbit/s using terahertz radiation. Such an antenna would broadcast in the frequency range. Unlike X-rays, terahertz radiation is not ionizing radiation and its low photon energies in general do not damage tissues, some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content and reflect back
6.
Electromagnetic spectrum
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The electromagnetic spectrum is the collective term for all known frequencies and their linked wavelengths of the known photons. The electromagnetic spectrum of an object has a different meaning, and is instead the characteristic distribution of radiation emitted or absorbed by that particular object. Visible light lies toward the end, with wavelengths from 400 to 700 nanometres. The limit for long wavelengths is the size of the universe itself, until the middle of the 20th century it was believed by most physicists that this spectrum was infinite and continuous. Nearly all types of radiation can be used for spectroscopy, to study. Other technological uses are described under electromagnetic radiation, for most of history, visible light was the only known part of the electromagnetic spectrum. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, the study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle. The first discovery of electromagnetic radiation other than visible light came in 1800 and he was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red and he theorized that this temperature change was due to calorific rays that were a type of light ray that could not be seen. The next year, Johann Ritter, working at the end of the spectrum. These behaved similarly to visible light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation, during the 1860s James Maxwell developed four partial differential equations for the electromagnetic field. Two of these equations predicted the possibility of, and behavior of, analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave, maxwells equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the electromagnetic spectrum. Maxwells predicted waves included waves at very low compared to infrared. Hertz found the waves and was able to infer that they traveled at the speed of light, Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media, in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin, in a later experiment, Hertz similarly produced and measured the properties of microwaves
7.
Far infrared
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Far infrared is a region in the infrared spectrum of electromagnetic radiation. Far infrared is defined as any radiation with a wavelength of 15 micrometers to 1 mm. Different sources use different boundaries for the far infrared spectrum, for example, visible light includes radiation with wavelengths between 400 nm and 700 nm, meaning that far infrared photons have less energy than visible light photons. Objects with temperatures between about 5 K and 340 K will emit radiation in the far infrared range and this property is sometimes used to observe interstellar gases where new stars are often formed. This is due to the dust at the center of M82 being heated by an unknown source, as of 2015, recently developed electric or hydronic panel-based longwave infrared heaters are becoming more adopted. Some human proximity sensors use passive infrared sensing in the far infrared wavelength to detect both static and/or moving human bodies. The infrared radiation band covers the range of 700 nm –1 mm, frequency range of 430 THz –300 GHz. Far-infrared fadiation is found on the spectrum at 15–1000 µm with a frequency range of 0. 3–20 THz. They report that this radiant heat can penetrate up to 1.5 inches beneath the skin, biomedical researchers have experimented with the use of FIR emitting ceramics which are embedded into various fibers and woven into the fabric of garments. These researchers noted in subjects a delay in the onset of fatigue induced by muscle contractions and they propose that this ceramic-emitted FIR has the potential to promote cell repair. The American athletic apparel company, Under Armour Under Armour, Inc, far infrared radiation, its biological effects and medical applications
8.
Microwave
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Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter, with frequencies between 300 MHz and 300 GHz. Different sources define different frequency ranges as microwaves, the broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz, in all cases, microwaves include the entire SHF band at minimum. Frequencies in the range are often referred to by their IEEE radar band designations, S, C, X, Ku, K, or Ka band. The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range and it indicates that microwaves are small, compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. At the high end of the band they are absorbed by gases in the atmosphere, microwaves are extremely widely used in modern technology. Although at the low end of the band they can pass through building walls enough for useful reception, therefore on the surface of the Earth microwave communication links are limited by the visual horizon to about 30 -40 miles. Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies, in a microwave beam directed at an angle into the sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere. A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter communication systems to communicate beyond the horizon and their short wavelength allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. Therefore beams of microwaves are used for point-to-point communication links, an advantage of narrow beams is that they allow frequency reuse by nearby transmitters. Parabolic antennas are the most widely used directive antennas at microwave frequencies, flat microstrip antennas are being increasingly used in consumer devices. Where omnidirectional antennas are required, for example in wireless devices and Wifi routers for wireless LANs, small monopoles, dipole, or patch antennas are used. Due to the high cost and maintenance requirements of waveguide runs, the term microwave also has a more technical meaning in electromagnetics and circuit theory. As a consequence, practical microwave circuits tend to away from the discrete resistors, capacitors. Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline, high-power microwave sources use specialized vacuum tubes to generate microwaves
9.
Molecular cloud
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A molecular cloud, sometimes called a stellar nursery, is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen. This is in contrast to areas of the interstellar medium that contain predominantly ionized gas. Molecular hydrogen is difficult to detect by infrared and radio observations, the ratio between CO luminosity and H2 mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies. Within molecular clouds are regions with higher density, where lots of dust and gas cores reside and these clumps are the beginning of star formation, if gravity can overcome the high density and force the dust and gas to collapse. The bulk of the gas is contained in a ring between 3.5 and 7.5 kiloparsecs from the center of the Milky Way. Large scale CO maps of the show that the position of this gas correlates with the spiral arms of the galaxy. A vast assemblage of molecular gas with a mass of approximately 103 to 107 times the mass of the Sun is called a giant molecular cloud, GMCs are around 15 to 600 light-years in diameter. Whereas the average density in the vicinity is one particle per cubic centimetre. Although the Sun is much more dense than a GMC, the volume of a GMC is so great that it much more mass than the Sun. The substructure of a GMC is a pattern of filaments, sheets, bubbles. Observationally, typical molecular cores are traced with CO and dense molecular cores are traced with ammonia, the concentration of dust within molecular cores is normally sufficient to block light from background stars so that they appear in silhouette as dark nebulae. These local GMCs are arrayed in a ring in the neighborhood of the Sun coinciding with the Gould Belt, the Sagittarius region is chemically rich and is often used as an exemplar by astronomers searching for new molecules in interstellar space. Isolated gravitationally-bound small molecular clouds with masses less than a few hundred times that of the Sun are called Bok globules, the densest parts of small molecular clouds are equivalent to the molecular cores found in GMCs and are often included in the same studies. In 1984 IRAS identified a new type of diffuse molecular cloud and these were diffuse filamentary clouds that are visible at high galactic latitudes. These clouds have a density of 30 particles per cubic centimeter. The formation of stars occurs exclusively within molecular clouds, there is observed evidence that the large, star-forming clouds are confined to a large degree by their own gravity rather than by external pressure. The evidence comes from the fact that the turbulent velocities inferred from CO linewidth scale in the manner as the orbital velocity. The physics of clouds are poorly understood and much debated
10.
Dark nebula
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A dark nebula or absorption nebula is a type of interstellar cloud that is so dense that it obscures the light from objects behind it, such as background stars and emission or reflection nebulae. The extinction of the light is caused by interstellar dust grains located in the coldest, densest parts of molecular clouds. Clusters and large complexes of dark nebulae are associated with Giant Molecular Clouds, isolated small dark nebulae are called Bok globules. Like other interstellar dust or material, things it obscures are only visible using radio waves in radio astronomy or infrared in infrared astronomy. Dark clouds appear so because of sub-micrometre-sized dust particles, coated with carbon monoxide and nitrogen. Also present are molecular hydrogen, atomic helium, C18O, CS, NH3, H2CO, c-C3H2 and these clouds are the spawning grounds of stars and planets, and understanding their development is essential to understanding star formation. The form of dark clouds is very irregular, they have no clearly defined outer boundaries and sometimes take on convoluted serpentine shapes. The largest dark nebulae are visible to the eye, appearing as dark patches against the brighter background of the Milky Way like the Coalsack Nebula. These naked-eye objects are known as dark cloud constellations and take on a variety of names. In the inner outer molecular regions of dark nebulae, important events take place, list of dark nebulae Bok globule
11.
Star formation
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Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as stellar nurseries or star-forming regions, fuse to form stars. It is closely related to formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a star, must also account for the statistics of binary stars. In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z =6.60, a spiral galaxy like the Milky Way contains stars, stellar remnants, and a diffuse interstellar medium of gas and dust. The interstellar medium consists of 10−4 to 106 particles per cm3 and is composed of roughly 70% hydrogen by mass. This medium has been enriched by trace amounts of heavier elements that were ejected from stars as they passed beyond the end of their main sequence lifetime. Higher density regions of the interstellar medium form clouds, or diffuse nebulae, in the dense nebulae where stars are produced, much of the hydrogen is in the molecular form, so these nebulae are called molecular clouds. These giant molecular clouds have densities of 100 particles per cm3, diameters of 100 light-years, masses of up to 6 million solar masses. About half the mass of the galactic ISM is found in molecular clouds and in the Milky Way there are an estimated 6,000 molecular clouds. The nearest nebula to the Sun where massive stars are being formed is the Orion nebula,1,300 ly away, however, lower mass star formation is occurring about 400–450 light years distant in the ρ Ophiuchi cloud complex. A more compact site of formation is the opaque clouds of dense gas and dust known as Bok globules. These can form in association with collapsing molecular clouds or possibly independently, the Bok globules are typically up to a light year across and contain a few solar masses. They can be observed as dark clouds silhouetted against bright emission nebulae or background stars, over half the known Bok globules have been found to contain newly forming stars. An interstellar cloud of gas will remain in equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the theorem, which states that, to maintain equilibrium. If a cloud is massive enough that the gas pressure is insufficient to support it, the mass above which a cloud will undergo such collapse is called the Jeans mass. The Jeans mass depends on the temperature and density of the cloud and this coincides with the typical mass of an open cluster of stars, which is the end product of a collapsing cloud. In triggered star formation, one of several events occur to compress a molecular cloud
12.
Gravitational collapse
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Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of mass. Gravitational collapse is a mechanism for structure formation in the universe. A star is born through the gravitational collapse of a cloud of interstellar matter. The star then exists in a state of dynamic equilibrium, once all its energy sources are exhausted, a star will again collapse until it reaches a new equilibrium state. An interstellar cloud of gas will remain in equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the theorem, which states that, to maintain equilibrium. If a pocket of gas is enough that the gas pressure is insufficient to support it. The mass above which a cloud will undergo such collapse is called the Jeans mass and this mass depends on the temperature and density of the cloud, but is typically thousands to tens of thousands of solar masses. At what is called the death of the star, it will undergo a contraction that can be halted if it reaches a new state of equilibrium. If it has a star, a white dwarf-sized object can accrete matter from the companion star until it reaches the Chandrasekhar limit at which point gravitational collapse takes over again. While it might seem that the white dwarf might collapse to the stage, they instead undergo runaway carbon fusion. Neutron stars are formed by collapse of the cores of larger stars. They are so compact that a Newtonian description is inadequate for an accurate treatment, hence, the collapse continues with nothing to stop it. Once a body collapses to within its Schwarzschild radius it forms what is called a black hole and it follows from a theorem of Roger Penrose that the subsequent formation of some kind of singularity is inevitable. On the other hand, the nature of the kind of singularity to be expected inside a hole remains rather controversial. According to some theories, at a stage, the collapsing object will reach the maximum possible energy density for a certain volume of space or the Planck density. This is when the laws of gravity cease to be valid. There are competing theories as to what occurs at this point, the radii of larger mass neutron stars are estimated to be about 12-km, or approximately 2.0 times their equivalent Schwarzschild radius
13.
Interstellar medium
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In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and it fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of radiation, is the interstellar radiation field. The interstellar medium is composed of phases, distinguished by whether matter is ionic, atomic, or molecular. The interstellar medium is composed primarily of hydrogen followed by helium with trace amounts of carbon, oxygen, the thermal pressures of these phases are in rough equilibrium with one another. Magnetic fields and turbulent motions also provide pressure in the ISM, in all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, in hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a density of roughly 1019 molecules per cm3 for air at sea level. By mass, 99% of the ISM is gas in any form, and 1% is dust. Of the gas in the ISM, by number 91% of atoms are hydrogen and 9% are helium, with 0. 1% being atoms of elements heavier than hydrogen or helium, by mass this amounts to 70% hydrogen, 28% helium, and 1. 5% heavier elements. The hydrogen and helium are primarily a result of primordial nucleosynthesis, the ISM plays a crucial role in astrophysics precisely because of its intermediate role between stellar and galactic scales. Stars form within the densest regions of the ISM, molecular clouds, and replenish the ISM with matter and energy through planetary nebulae, stellar winds, and supernovae. This interplay between stars and the ISM helps determine the rate at which a galaxy depletes its gaseous content, voyager 1 reached the ISM on August 25,2012, making it the first artificial object from Earth to do so. Interstellar plasma and dust will be studied until the end in 2025. Table 1 shows a breakdown of the properties of the components of the ISM of the Milky Way, field, Goldsmith & Habing put forward the static two phase equilibrium model to explain the observed properties of the ISM. Their modeled ISM consisted of a dense phase, consisting of clouds of neutral and molecular hydrogen. McKee & Ostriker added a third phase that represented the very hot gas which had been shock heated by supernovae. These phases are the temperatures where heating and cooling can reach a stable equilibrium and their paper formed the basis for further study over the past three decades
14.
Galaxy formation and evolution
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Galaxy formation is hypothesized to occur, from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. Because of the inability to conduct experiments in space, the only way to “test” theories. Explanations for how galaxies formed and evolved must be able to predict the properties and types of galaxies. Edwin Hubble created the first galaxy classification scheme known as the Hubble tuning-fork diagram and it partitioned galaxies into ellipticals, normal spirals, barred spirals, and irregulars. These groups divide into blue star-forming galaxies that are more like spiral types, spiral galaxies are quite thin, dense, and rotate relatively fast, while the stars in elliptical galaxies have randomly-oriented orbits. The majority of mass in galaxies is made up of matter, a substance which is not directly observable. The majority of giant galaxies contain a black hole in their centers. The black hole mass is tied to the host galaxy bulge or spheroid mass, metallicity has a positive correlation with the absolute magnitude of a galaxy. This is not the case instead the tuning fork diagram shows an evolution from simple to complex with no temporal connotations intended, astronomers now believe that disk galaxies likely formed first, then evolved into elliptical galaxies through galaxy mergers. The earliest stage in the evolution of galaxies is the formation, when a galaxy forms, it has a disk shape and is called a spiral galaxy due to spiral-like arm structures located on the disk. There are different theories on how these disk-like distributions of stars develop from a cloud of matter, however, at present, olin Eggen, Donald Lynden-Bell, and Allan Sandage in 1962, proposed a theory that disk galaxies form through a monolithic collapse of a large gas cloud. The distribution of matter in the universe was in clumps that consisted mostly of dark matter. These clumps interacted gravitationally, putting tidal torques on each other that acted to give them some angular momentum, as the baryonic matter cooled, it dissipated some energy and contracted toward the center. With angular momentum conserved, the matter near the center speeds up its rotation, then, like a spinning ball of pizza dough, the matter forms into a tight disk. Once the disk cools, the gas is not gravitationally stable and it breaks, and these smaller clouds of gas form stars. Since the dark matter does not dissipate as it only interacts gravitationally, observations show that there are stars located outside the disk, which does not quite fit the pizza dough model. It was first proposed by Leonard Searle and Robert Zinn that galaxies form by the coalescence of smaller progenitors, known as a top-down formation scenario, this theory is quite simple yet no longer widely accepted. More recent theories include the clustering of dark matter halos in the bottom-up process and this still results in disk-like distributions of baryonic matter with dark matter forming the halo for all the same reasons as in the top-down theory
15.
Atacama Large Millimeter Array
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The Atacama Large Millimeter Array is an astronomical interferometer of radio telescopes in the Atacama desert of northern Chile. ALMA is a partnership among Europe, the United States, Canada, Japan, South Korea, Taiwan. Costing about US$1.4 billion, it is the most expensive ground-based telescope in operation, ALMA began scientific observations in the second half of 2011 and the first images were released to the press on 3 October 2011. The array has been operational since March 2013. The initial ALMA array is composed of 66 high-precision antennas, the high sensitivity is mainly achieved through the large numbers of antenna dishes that will make up the array. The telescopes were provided by the European, North American and East Asian partners of ALMA, the American and European partners each provided twenty-five 12-meter diameter antennas, that compose the main array. The participating East Asian countries are contributing 16 antennas in the form of the Atacama Compact Array, by using smaller antennas than the main ALMA array, larger fields of view can be imaged at a given frequency using ACA. Placing the antennas closer together enables the imaging of sources of larger angular extent, the ACA works together with the main array in order to enhance the latters wide-field imaging capability. ALMA has its roots in three astronomical projects — the Millimeter Array of the United States, the Large Southern Array of Europe. The merged array combined the sensitivity of the LSA with the frequency coverage, ESO and NRAO worked together in technical, science, and management groups to define and organize a joint project between the two observatories with participation by Canada and Spain. A groundbreaking ceremony was held on November 6,2003 and the ALMA logo was unveiled and this was mainly for political reasons. Although very different approaches have been chosen by the providers, each of the antenna designs appears to be able to meet ALMAs stringent requirements, ALMA is the largest and most expensive ground-based astronomical project, costing between US$1.4 and 1.5 billion. S. Japanese, and Canadian companies and universities, three prototype antennas have undergone evaluation at the Very Large Array since 2002. The first antenna was delivered in 2008, the last in 2011, the solution chosen is to use two custom 28-wheel self-loading heavy haulers. The vehicles were made by Scheuerle Fahrzeugfabrik in Germany and are 10 m wide,20 m long and 6 m high and they are powered by twin turbocharged 500 kW Diesel engines. The transporters, which feature a drivers seat designed to accommodate an oxygen tank to aid breathing the thin high-altitude air, the first vehicle was completed and tested in July 2007. Both transporters were delivered to the ALMA Operations Support Facility in Chile on 15 February 2008, on 7 July 2008, an ALMA transporter moved an antenna for the first time, from inside the antenna assembly building to a pad outside the building for testing. During Autumn 2009, the first three antennas were transported one-by-one to the Array Operations Site, linking three antennas allows corrections of errors that can arise when only two antennas are used, thus paving the way for precise, high-resolution imaging
16.
Water vapor
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Water vapor, water vapour or aqueous vapor, is the gaseous phase of water. It is one state of water within the hydrosphere, water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Unlike other forms of water, water vapor is invisible, under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is lighter than air and triggers convection currents that can lead to clouds, use of water vapor, as steam, has been important to humans for cooking and as a major component in energy production and transport systems since the industrial revolution. Likewise the detection of water vapor would indicate a similar distribution in other planetary systems. Water vapor is significant in that it can be evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects. Whenever a water molecule leaves a surface and diffuses into a surrounding gas, each individual water molecule which transitions between a more associated and a less associated state does so through the absorption or release of kinetic energy. The aggregate measurement of kinetic energy transfer is defined as thermal energy. Liquid water that becomes water vapor takes a parcel of heat with it, the amount of water vapor in the air determines how fast each molecule will return to the surface. When a net evaporation occurs, the body of water will undergo a net cooling directly related to the loss of water, in the US, the National Weather Service measures the actual rate of evaporation from a standardized pan open water surface outdoors, at various locations nationwide. Others do likewise around the world, the US data is collected and compiled into an annual evaporation map. The measurements range from under 30 to over 120 inches per year, formulas can be used for calculating the rate of evaporation from a water surface such as a swimming pool. In some countries, the evaporation rate far exceeds the precipitation rate, evaporative cooling is restricted by atmospheric conditions. Humidity is the amount of vapor in the air. The vapor content of air is measured with devices known as hygrometers, the measurements are usually expressed as specific humidity or percent relative humidity. This condition is referred to as complete saturation. Humidity ranges from 0 gram per cubic metre in dry air to 30 grams per cubic metre when the vapor is saturated at 30 °C, another form of evaporation is sublimation, by which water molecules become gaseous directly, leaving the surface of ice without first becoming liquid water. Sublimation accounts for the slow disappearance of ice and snow at temperatures too low to cause melting
17.
Absorption (electromagnetic radiation)
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In physics, absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the energy is transformed into internal energy of the absorber. The reduction in intensity of a wave propagating through a medium by absorption of a part of its photons is often called attenuation. The mass attenuation coefficient, also called mass extinction coefficient, which is the absorption coefficient divided by density, the absorption cross section and scattering cross-section are closely related to the absorption and attenuation coefficients, respectively. Extinction in astronomy is equivalent to the attenuation coefficient, absorbance and optical depth are two related measures All these quantities measure, at least to some extent, how well a medium absorbs radiation. However, practitioners of different fields and techniques tend to use different quantities drawn from the list above. The absorbance of an object quantifies how much of the incident light is absorbed by it and this may be related to other properties of the object through the Beer–Lambert law. A few examples of absorption are ultraviolet–visible spectroscopy, infrared spectroscopy, understanding and measuring the absorption of electromagnetic radiation has a variety of applications. Here are a few examples, In meteorology and climatology, global and local temperatures depend in part on the absorption of radiation by gases and land. In medicine, X-rays are absorbed to different extents by different tissues, for example, see computation of radiowave attenuation in the atmosphere used in satellite link design. In chemistry and materials science, because different materials and molecules will absorb radiation to different extents at different frequencies, in optics, sunglasses, colored filters, dyes, and other such materials are designed specifically with respect to which visible wavelengths they absorb, and in what proportions. In physics, the D-region of Earths ionosphere is known to significantly absorb radio signals that fall within the electromagnetic spectrum. Optical Propagation in Linear Media, Atmospheric Gases and Particles, Solid-State Components, physics Archive - Ask a scientist
18.
Hawaii
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Hawaii is the 50th and most recent state to have joined the United States of America, having received statehood on August 21,1959. Hawaii is the only U. S. state located in Oceania and it is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean. Hawaii is the only U. S. state not located in the Americas, the state encompasses nearly the entire volcanic Hawaiian archipelago, which comprises hundreds of islands spread over 1,500 miles. At the southeastern end of the archipelago, the eight main islands are—in order from northwest to southeast, Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and the Island of Hawaiʻi. The last is the largest island in the group, it is called the Big Island or Hawaiʻi Island to avoid confusion with the state or archipelago. The archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania, Hawaii has over a million permanent residents, along with many visitors and U. S. military personnel. Its capital is Honolulu on the island of Oʻahu, Hawaii is the 8th-smallest and the 11th-least populous, but the 13th-most densely populated of the fifty U. S. states. It is the state with an Asian plurality. The states coastline is about 750 miles long, the fourth longest in the U. S. after the coastlines of Alaska, Florida, the state of Hawaii derives its name from the name of its largest island, Hawaiʻi. A common Hawaiian explanation of the name of Hawaiʻi is that was named for Hawaiʻiloa and he is said to have discovered the islands when they were first settled. The Hawaiian language word Hawaiʻi is very similar to Proto-Polynesian *Sawaiki, cognates of Hawaiʻi are found in other Polynesian languages, including Māori, Rarotongan and Samoan. According to linguists Pukui and Elbert, lsewhere in Polynesia, Hawaiʻi or a cognate is the name of the underworld or of the home, but in Hawaii. A somewhat divisive political issue arose in 1978 when the Constitution of the State of Hawaii added Hawaiian as an official state language. The title of the constitution is The Constitution of the State of Hawaii. Article XV, Section 1 of the Constitution uses The State of Hawaii, diacritics were not used because the document, drafted in 1949, predates the use of the okina and the kahakō in modern Hawaiian orthography. The exact spelling of the name in the Hawaiian language is Hawaiʻi. In the Hawaii Admission Act that granted Hawaiian statehood, the government recognized Hawaii as the official state name. Official government publications, department and office titles, and the Seal of Hawaii use the spelling with no symbols for glottal stops or vowel length
19.
Llano de Chajnantor Observatory
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Llano de Chajnantor Observatory is the name for a group of astronomical observatories located at an altitude of over 4,800 m in the Atacama Desert of northern Chile. The site is in the Antofagasta Region approximately 50 kilometres east of the town of San Pedro de Atacama, the exceptionally arid climate of the area is inhospitable to humans, but creates an excellent location for millimeter, submillimeter, and mid-infrared astronomy. This is because water vapour absorbs and attenuates submillimetre radiation, Llano de Chajnantor is home to the largest and most expensive astronomical telescope project in the world, the Atacama Large Millimeter Array. Llano de Chajnantor and the area has been designated as the Chajnantor Science Reserve by the government of Chile. The Llano de Chajnantor is located on the side of the Puna de Atacama. The main ridge of the Andes is over 200 kilometres to the east, the Salar de Atacama basin borders the Puna de Atacama to the west, which in turn is bordered by the Cordillera Domeyko. The western side of the Puna de Atacama is dotted with the volcanoes of the Central Volcanic Zone of the Andean Volcanic Belt. The Llano de Chajnantor site itself is bounded by volcanic peaks of the Purico Complex, Cerro Chajnantor is to the north, Cerro El Chascón to the east, and smaller peaks to the south and west. The Pampa la Bola lies to the northeast, north of Cerro El Chascón, Llano de Chajnantor has an average elevation of 5,000 m, while Pampa la Bola averages 4,800 m. The thin atmosphere makes work difficult for humans, so much of the activity for ALMA will be conducted at a camp in the Salar de Atacama basin at approximately 2,900 m in elevation. Rainfall at the ALMA site averages 100 mm annually, while the site is generally viewed as being in the Atacama Desert, in terms of ecoregions it is in the Central Andean dry puna. Llano de Chajnantor is at the latitude as deserts in southern Africa. The Atacama Large Millimeter Array is a large radio telescope interferometer at Llano de Chajnantor. It has been in operation since October 2013. The Atacama Pathfinder Experiment is a 12 m submillimetre radio telescope installed in 2003 and its design is based on the North American ALMA prototype antenna modified for single dish use. It is operated by a led by the Max Planck Institute for Radio Astronomy. The Atacama Submillimeter Telescope Experiment is a 10 m submillimetre radio telescope built by Mitsubishi Electric and it was an early prototype for the antennas of ALMA, and is operated by a consortium led by the National Astronomical Observatory of Japan. It was first built in Japan in 2000, and then was reassembled in Chile in 2002 and it began regular observations in 2004
20.
Chile
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Chile, officially the Republic of Chile, is a South American country occupying a long, narrow strip of land between the Andes to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, Chilean territory includes the Pacific islands of Juan Fernández, Salas y Gómez, Desventuradas, and Easter Island in Oceania. Chile also claims about 1,250,000 square kilometres of Antarctica, the arid Atacama Desert in northern Chile contains great mineral wealth, principally copper. Southern Chile is rich in forests and grazing lands, and features a string of volcanoes and lakes, the southern coast is a labyrinth of fjords, inlets, canals, twisting peninsulas, and islands. Spain conquered and colonized Chile in the century, replacing Inca rule in northern and central Chile. After declaring its independence from Spain in 1818, Chile emerged in the 1830s as a relatively stable authoritarian republic, in the 1960s and 1970s the country experienced severe left-right political polarization and turmoil. The regime, headed by Augusto Pinochet, ended in 1990 after it lost a referendum in 1988 and was succeeded by a coalition which ruled through four presidencies until 2010. Chile is today one of South Americas most stable and prosperous nations and it leads Latin American nations in rankings of human development, competitiveness, income per capita, globalization, state of peace, economic freedom, and low perception of corruption. It also ranks high regionally in sustainability of the state, Chile is a founding member of the United Nations, the Union of South American Nations and the Community of Latin American and Caribbean States. There are various theories about the origin of the word Chile, another theory points to the similarity of the valley of the Aconcagua with that of the Casma Valley in Peru, where there was a town and valley named Chili. Another origin attributed to chilli is the onomatopoeic cheele-cheele—the Mapuche imitation of the warble of a locally known as trile. The Spanish conquistadors heard about this name from the Incas, ultimately, Almagro is credited with the universalization of the name Chile, after naming the Mapocho valley as such. The older spelling Chili was in use in English until at least 1900 before switching over to Chile, stone tool evidence indicates humans sporadically frequented the Monte Verde valley area as long as 18,500 years ago. About 10,000 years ago, migrating Native Americans settled in fertile valleys, settlement sites from very early human habitation include Monte Verde, Cueva del Milodon and the Pali Aike Craters lava tube. They fought against the Sapa Inca Tupac Yupanqui and his army, the result of the bloody three-day confrontation known as the Battle of the Maule was that the Inca conquest of the territories of Chile ended at the Maule river. The next Europeans to reach Chile were Diego de Almagro and his band of Spanish conquistadors, the Spanish encountered various cultures that supported themselves principally through slash-and-burn agriculture and hunting. The conquest of Chile began in earnest in 1540 and was carried out by Pedro de Valdivia, one of Francisco Pizarros lieutenants, who founded the city of Santiago on 12 February 1541. Although the Spanish did not find the gold and silver they sought, they recognized the agricultural potential of Chiles central valley
21.
South Pole
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The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earths axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth, situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year. The Geographic South Pole should not be confused with the South Magnetic Pole, the South Pole is at the center of the Southern Hemisphere. For most purposes, the Geographic South Pole is defined as the point of the two points where the Earths axis of rotation intersects its surface. However, the Earths axis of rotation is actually subject to very small wobbles, the geographic coordinates of the South Pole are usually given simply as 90°S, since its longitude is geometrically undefined and irrelevant. When a longitude is desired, it may be given as 0°, at the South Pole, all directions face north. For this reason, directions at the Pole are given relative to grid north, along tight latitude circles, clockwise is east, and counterclockwise is west, opposite to the North Pole. The Geographic South Pole is located on the continent of Antarctica. It sits atop a featureless, barren, windswept and icy plateau at an altitude of 2,835 metres above sea level, and is located about 1,300 km from the nearest open sea at Bay of Whales. The ice is estimated to be about 2,700 metres thick at the Pole, the polar ice sheet is moving at a rate of roughly 10 metres per year in a direction between 37° and 40° west of grid north, down towards the Weddell Sea. Therefore, the position of the station and other artificial features relative to the geographic pole gradually shift over time. The Geographic South Pole is marked by a stake in the ice alongside a small sign, these are repositioned each year in a ceremony on New Years Day to compensate for the movement of the ice. The sign records the respective dates that Roald Amundsen and Robert F. Scott reached the Pole, followed by a quotation from each man. A new marker stake is designed and fabricated each year by staff at the site, the Ceremonial South Pole is an area set aside for photo opportunities at the South Pole Station. It is located around 180 metres from the Geographic South Pole, Amundsens Tent, The tent was erected by the Norwegian expedition led by Roald Amundsen on its arrival on 14 December 1911. It is currently buried beneath the snow and ice in the vicinity of the Pole and it has been designated a Historic Site or Monument, following a proposal by Norway to the Antarctic Treaty Consultative Meeting. In 1820, several expeditions claimed to have been the first to have sighted Antarctica, with the very first being the Russian expedition led by Faddey Bellingshausen and Mikhail Lazarev. The first landing was probably just over a year later when American Captain John Davis, the basic geography of the Antarctic coastline was not understood until the mid-to-late 19th century
22.
Indian Astronomical Observatory
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The Indian Astronomical Observatory, located near Leh in Ladakh, India, has one of the worlds highest sites for optical, infrared and gamma-ray telescopes. It is operated by the Indian Institute of Astrophysics, Bangalore and it is currently the second highest optical telescope in the world, situated at an elevation of 4,500 meters. The Indian Astronomical Observatory stands on Mt. Saraswati, Digpa-ratsa Ri, Hanle in south-eastern Ladakh in the eastern Jammu, accessing the observatory, located near the Chinese border, requires a ten-hour drive from Leh, the district capital of Ladakh. In the late 1980s a committee chaired by Prof. B. V. Sreekantan recommended that a large optical telescope be taken up as a priority project. The search for the site of the observatory was taken up in 1992 under the leadership of Prof. Arvind Bhatnagar, the scientists from the Indian Institute of Astrophysics found the site at Hanle. The first light was seen by the Observatory 2-metre telescope on the hour between 26 September and 27 September 2000. The Observatory was dedicated to the nation on 29 August 2001, the Hanle site is deemed to be excellent for visible, infrared and submillimeter observations throughout the year. Specifically the observation conditions yield about 255 spectroscopic nights per year, approximately 190 photometric nights per year, in addition, there are low ambient temperatures, low humidity, low concentration of atmospheric aerosols, low atmospheric water vapour, dark nights and low pollution. The Observatory has two active telescopes and these are the 2.01 meter optical-infrared Himalayan Chandra Telescope and a High Altitude Gamma Ray Telescope. The HCT is remotely operated from Bangalore from the Centre for Research and Education in Science, the Himalayan Chandra Telescope is a 2.01 meters diameter optical-infrared telescope named after India-born Nobel laureate Subrahmanyam Chandrasekhar. It contains a modified Ritchey-Chretien system with a mirror made of ULE ceramic which is designed to withstand low temperatures it experiences. The telescope was manufactured by Electo-Optical System Technologies Inc. at Tucson, Arizona, the telescope is mounted with 3 science instruments called Himalaya Faint Object Spectrograph, the near-IR imager and the optical CCD imager. The telescope is operated via an INSAT-3B satellite link which allows operation even in sub-zero temperatures in winter. The High Altitude Gamma Ray Telescope is an atmospheric Cerenkov experiment with 7 telescopes setup in 2008, each telescope has 7 mirrors with a total area of 4.4 square meters. The telescopes are deployed on the periphery of a circle of radius 50 meters with one telescope at the center, the Center for Research and Education in Science and Technology is situated 35 km to the northeast of Bangalore near Hoskote town. The Center houses the control room for the operations of the 2m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle. The operations are controlled using a satellite link. One of the observatories is to be established in Hanle, the facilities 180 degrees apart in longitude are together to be called the Antipodal Transient Observatory
23.
Summit Camp
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Summit Camp, also Summit Station, is a year-round research station on the apex of the Greenland Ice Sheet. Its coordinates are variable, since the ice is moving, the coordinates provided here are as of July 2009. The station is located 3,216 metres above sea level, the population of the station is typically five in wintertime, and has peaked at 55 in the summer. The station is operated by the American-based CH2M HILL Polar Services, a permit from the Danish Polar Center under the auspices of the Home Rule Government of Greenland is required to visit the station. The camp is located approximately 360 km from the east coast and 500 km from the west coast of Greenland at, the closest town is Ittoqqortoormiit,460 km east-southeast of the station. The station however is not part of Sermersooq municipality, but falls within the bounds of the Northeast Greenland National Park, Summit Camp consists of the Big House, Greenhouse with attached Berthing Module, a combined garage and generator building, the summertime Tent City, and storage buildings. Summit Camp was originally established in April 1989 in support of the Greenland Ice Sheet Project Two deep ice coring effort and they located the exact location chosen for the GISP2 drilling site, established a camp, and laid out the runway. Subsequent flights brought in additional materials and personnel needed to build the station, Two major structures were planned and built, The Big House, an insulated panel building, elevated to minimize snow drifts, and a geodesic drill dome to house the deep drill. Extensive under-snow trenches were constructed to house the core handling, processing. Many smaller Weatherport hut buildings and tents were erected as storage. These were erected and taken down each season, on July 1,1993, the bedrock was reached. Originally a summer only, the station had been manned year round since the early 2000s. The climate is classified as polar, and the weather is highly variable, typical daily maximum temperatures at Summit Camp are around −35 °C in winter and −10 °C in summer. Winter minimum temperatures are typically about −45 °C and only rarely exceed −20 °C, annual precipitation is about 3,000 mm, much of which falls as sleet or snow, which is possible in any month. Inland, the line in summer is at an altitude of about 300 m. The highest temperature at Summit Camp was 3.6 °C, recorded on July 16,2012, in July 2012, satellite imagery showed there was an unprecedented melt of the Greenland ice sheet. In just four days from 8 July, the area of thawed surface ice grew from 40% to almost 97% of the ice sheet surface. Winter access is infrequent, using smaller, ski-equipped aircraft such as a Twin Otter flown by Air Greenland
24.
Atacama Pathfinder Experiment
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The main dish has a diameter of 12 m and consists of 264 aluminium panels with an average surface accuracy of 17 micrometres. The telescope was inaugurated on September 25,2005. The APEX telescope is a modified ALMA prototype antenna and is at the site of the ALMA observatory. APEX is designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range — between infrared light and radio waves — and to find targets that ALMA will be able to study in greater detail. Submillimetre astronomy provides a window into the cold, dusty and distant Universe, the telescope was designed and constructed by the German firm VERTEX Antennentechnik GmbH, under contract by MPIfR. The operation of APEX on Chajnantor is entrusted to ESO, submillimetre astronomy is a relatively unexplored frontier in astronomy and reveals a Universe that cannot be seen in the more familiar visible or infrared light. It is ideal for studying the cold Universe, light at these wavelengths shines from vast cold clouds in interstellar space, at temperatures only a few tens of degrees above absolute zero. Astronomers use this light to study the chemical and physical conditions in these molecular clouds — the dense regions of gas and cosmic dust where new stars are being born. Seen in visible light, these regions of the Universe are often dark and obscured due to the dust and this wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe, whose light has been redshifted into these longer wavelengths. APEX science goals include studying the formation of stars, planets, and galaxies, including very distant galaxies in the early Universe, and the physical conditions of molecular clouds. Its first results proved the telescope lives up to the ambitions of the scientists by providing access to the cold Universe with unprecedented sensitivity and image quality. No fewer than 26 articles based on science with APEX were published in July 2006 in a special issue of the research journal Astronomy. APEX is also involved in the Global mm-VLBI Network and in the Event Horizon Telescope and these data follow the standard ESO archive rules, i. e. they become publicly available one year after they have been delivered to the principal investigator of the project. LABOCA uses an array of extremely sensitive micro-calorimeters — known as bolometers — to detect submillimetre light, with almost 300 elements, at the time of commissioning in 2007 LABOCA has been the largest bolometer camera in the world. To be able to detect the temperature changes caused by the faint submillimetre radiation. LABOCAs high sensitivity, together with its field of view. APEX first light was achieved in May 2004 using the SEST Imaging Bolometer Array that had moved to APEX after the decommissioning of the SEST. For more information about APEX instruments, consult the instrumentation page, to operate at the shorter sub-millimetre wavelengths, APEX presents a surface of exceedingly high quality
25.
Radio telescope
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A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy. Radio telescopes are typically large parabolic antennas similar to those employed in tracking and communicating with satellites and they may be used singly, or linked together electronically in an array. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night, Radio waves from space were first detected by engineer Karl Guthe Jansky in 1932 at Bell Telephone Laboratories in Holmdel, New Jersey using an antenna built to study noise in radio receivers. The first purpose-built radio telescope was a 9-meter parabolic dish constructed by radio amateur Grote Reber in his yard in Wheaton. The sky survey he did with it is considered the beginning of the field of radio astronomy. The first radio antenna used to identify an astronomical radio source was one built by Karl Guthe Jansky, Jansky was assigned the job of identifying sources of static that might interfere with radio telephone service. Janskys antenna was an array of dipoles and reflectors designed to receive short wave radio signals at a frequency of 20.5 MHz and it was mounted on a turntable that allowed it to rotate in any direction, earning it the name Janskys merry-go-round. It had a diameter of approximately 100 ft and stood 20 ft tall, by rotating the antenna, the direction of the received interfering radio source could be pinpointed. A small shed to the side of the antenna housed an analog recording system. Jansky finally determined that the faint hiss repeated on a cycle of 23 hours and 56 minutes and this period is the length of an astronomical sidereal day, the time it takes any fixed object located on the celestial sphere to come back to the same location in the sky. An amateur radio operator, Grote Reber, was one of the pioneers of what became known as radio astronomy and he built the first parabolic dish radio telescope, a 9 metres in diameter) in his back yard in Wheaton, Illinois in 1937. The range of frequencies in the spectrum that makes up the radio spectrum is very large. This means that the types of antennas that are used as radio telescopes vary widely in design, size, at wavelengths of 30 meters to 3 meters, they are generally either directional antenna arrays similar to TV antennas or large stationary reflectors with moveable focal points. Since the wavelengths being observed with these types of antennas are so long, at shorter wavelengths parabolic dish antennas predominate. The angular resolution of an antenna is determined by the ratio of the diameter of the dish to the wavelength of the radio waves being observed. This dictates the size a radio telescope needs for a useful resolution. Radio telescopes that operate at wavelengths of 3 meters to 30 cm are usually well over 100 meters in diameter, telescopes working at wavelengths shorter than 30 cm range in size from 3 to 90 meters in diameter. The Wilkinson Microwave Anisotropy Probe mapped the Cosmic microwave background radiation in 5 different frequency bands, centered on 23 GHz,33 GHz,41 GHz,61 GHz, the worlds largest filled-aperture radio telescope is the Five hundred meter Aperture Spherical Telescope completed in 2016 by China
26.
Submillimeter Array
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The Submillimeter Array consists of eight 6-meter diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. All three of these observatories are located at Mauna Kea Observatory on Mauna Kea, Hawaii, the baseline lengths presently in use range from 16 to 508 meters, and up to 783 meters for eSMA operations. Although the array is capable of operating both day and night, most of the observations take place at nighttime when the phase stability is best. The SMA is jointly operated by the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy, the SMA is a multi-purpose instrument which can be used to observe diverse celestial phenomena. The SMA excels at observations of dust and gas with only a few tens of kelvins above absolute zero. Commonly observed classes of objects include star-forming molecular clouds in our own and other galaxies, highly redshifted galaxies, evolved stars, occasionally, bodies in the Solar System, such as planets, asteroids, comets and moons, are observed. The SMA has been used to discover that Pluto is 10 K cooler than expected and it was the first radio telescope to resolve Pluto and Charon as separate objects. The SMA is a part of the Event Horizon Telescope, which observes nearby supermassive black holes with a resolution comparable to the size of the objects event horizon. 4″N 155°28′40. 7″W
27.
James Clerk Maxwell Telescope
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The James Clerk Maxwell Telescope is a submillimetre-wavelength telescope at Mauna Kea Observatory in Hawaii. The telescope is near the summit of Mauna Kea at 13,425 feet and its primary mirror is 15 metres across, it is the largest single-dish telescope that operates in submillimetre wavelengths of the electromagnetic spectrum. Scientists use it to study the Solar System, interstellar dust and gas, the JCMT started operations in 1987, and was funded until February 2015 by a partnership between the United Kingdom and Canada, and the Netherlands. It was operated by the Joint Astronomy Centre and was named in honour of mathematical physicist James Clerk Maxwell, in March 2015 the operation of the JCMT was taken over by the East Asian Observatory. The JCMT has the second-largest telescope mirror on Mauna Kea, the telescope was combined with the Caltech Submillimeter Observatory next to it, to form the first submillimetre interferometer. This success was important in pushing ahead the construction of the later Submillimeter Array, in the late 1960s, the Astronomy Committee of the UKs Science Research Council considered the importance of astronomical observations at submillimetre and millimetre wavelengths. The project, then called the National New Technology Telescope, was to be an 80/20 per cent collaboration with the Netherlands Organisation for the Advancement of Science. Site tests were made at Mauna Kea in Hawaii, the Pinaleno Mountains in Arizona, and a site in Chile, the NNTT was to be larger and with more instruments than competing telescopes such as the CSO and SMT. The final specifications called for the worlds largest telescope optimised for submillimetre wavelengths and it was to be a parabolic 15-metre antenna composed of 276 individually adjustable panels with a surface accuracy of better than 50 µm. It would be an altitude-azimuth mounted Cassegrain telescope with a mirror to direct the incoming radiation onto a number of different receivers. The antenna and mountings were to be protected from the elements by a carousel with a transparent membrane stretched across the carousel aperture. Building work started in 1983 and went well apart from a delay caused by the hijacking of the ship carrying the telescope across the Pacific by modern-day pirates. The telescope saw first light in 1987, the name for the final facility was changed to the James Clerk Maxwell Telescope. The telescope itself was operated by the Joint Astronomy Centre, from Hilo, from 1987 until March 2013 this the telescope was funded by a partnership of the United Kingdom, Canada, and the Netherlands ). In 2013 the Netherlands withdrew, and until 2015 the shares became UK75 percent, the JCMT has two kinds of instruments—broadband continuum receivers and heterodyne detection spectral line receivers. Continuum emission is a tracer of star formation in galaxies and gives astronomers clues to the presence, distance. Within our own galaxy dust emission is associated with stellar nurseries, spectral-line observations can be used to identify particular molecules in molecular clouds, study their distribution and chemistry and determine gas velocity gradients across astronomical objects. The older continuum single pixel UKT14 bolometer receiver was replaced around 1995 by the Submillimetre Common-User Bolometer Array and this instrument operated simultaneously at wavelengths of 450 and 850 micron, and was sensitive to the thermal emission from interstellar dust
28.
High-altitude balloon
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High-altitude balloons are unmanned balloons, usually filled with helium or hydrogen and rarely methane, that are released into the stratosphere, generally attaining between 60,000 to 120,000 ft. In 2002, a balloon named BU60-1 attained 53.0 km, the most common type of high-altitude balloons are weather balloons. Other purposes include use as a platform for experiments in the upper atmosphere, modern balloons generally contain electronic equipment such as radio transmitters, cameras, or satellite navigation systems, such as GPS receivers. Due to the low cost of GPS and communications equipment, high-altitude ballooning is a popular hobby, charles provided large quantities of hydrogen, which had only been produced in small quantities previously, by mixing 540 kg of iron and 270 kg of sulfuric acid. The balloon, called Charlière, took 5 days to fill and was launched from Champ de Mars in Paris where 300,000 people gathered to watch the spectacle, the balloon was launched and rose through the clouds. The expansion of the gas caused the balloon to tear and it descended 45 minutes later 20 km away from Paris, manned high-altitude balloons were used from the 1930s to 1960s for research and in seeking flight altitude records. Unmanned high-altitude balloons are used as Research balloons, common uses include weather balloons, as well as atmospheric and climate research. They are also used to collect data and imagery from near space. High-altitude ballooning is used for applications such as submillimetre astronomy. High-altitude balloons have been considered for use in space tourism, private companies such as zero2infinity and World View Enterprises are developing both manned and unmanned high-altitude balloons for scientific research, commercial purposes, and space tourism. High-altitude platform stations have been proposed for such as communications relays. Testing radio range is often a component to these hobbies. Amateur radio is used with packet radio to communicate with 1200 baud using a system called Automatic Packet Reporting System back to the ground station. Smaller packages called micro or sometimes pico trackers are also built and these smaller trackers have used Morse code, Field Hell and RTTY to transmit their locations and other data. The first recorded amateur radio balloon launches are recorded to have taken place in Finland by the Ilmari program on May 28,1967. Amateur radio high-altitude ballooning is the application of analog and digital radio to weather balloons and was the name suggested by Ralph Wallio for this hobby. Often referred to as The Poormans Space Program, ARHAB allows amateurs to design functioning models of spacecraft, bill Brown is considered to have begun the modern ARHAB movement with his first launch of a balloon carrying an amateur radio transmitter on 15 August 1987. An ARHAB flight consists of a balloon, a parachute
29.
BLAST (telescope)
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The Balloon-borne Large Aperture Submillimeter Telescope is a submillimeter telescope that hangs from a high-altitude balloon. It has a 2-meter primary mirror that directs light into bolometer arrays operating at 250,350 and these arrays were developed for the SPIRE instrument on the Herschel Space Observatory. The third flight of BLAST in Antarctica was a scientific success and it has been rebuilt for a flight from Antarctica in the 2010-11 austral summer. This most recent flight of BLAST has a polarimeter to observe the light from star forming cores. The light is polarized due to magnetic fields and it is thought that the magnetic fields inhibit the collapse of the cores. The Herschel Space Observatory does not have a polarimeter, measure cold pre-stellar sources associated with the earliest stages of star and planet formation. Make high-resolution maps of diffuse galactic emission over a range of galactic latitudes. Filmmaker Paul Devlin made a film titled BLAST. about the project. Paul is the brother of cosmologist Mark Devlin, Principal Investigator of the BLAST project, bLASTs first flight was an engineering flight. BLASTs second flight was its first scientific flight, BLAST launched at 1,10 UTC June 12,2005 from Esrange, near Kiruna, Sweden and landed at 6,15 UTC June 16,2005 on Victoria Island, Northwest Territories, Canada. BLASTs third flight was its second scientific flight, BLAST launched at 1,54,10 UTC December 21,2006 from McMurdo Station, Antarctica and landed at 1,05 UTC January 2,2007756 km southwest of McMurdo. The hard drives containing the data it had collected were eventually located and recovered from the drag path, bLASTs fourth flight launched at 4,06 UTC December 27,2010 from Willy Field, McMurdo Station, Antarctica and landed on the Ross Ice Shelf
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Stratospheric Observatory for Infrared Astronomy
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The Stratospheric Observatory for Infrared Astronomy is an 80/20 joint project of NASA and the German Aerospace Center to construct and maintain an airborne observatory. NASA awarded the contract for the development of the aircraft, operation of the observatory, the DSI manages the German parts of the project which are primarily science and telescope related. SOFIAs telescope saw first light on May 26,2010, SOFIA is the successor to the Kuiper Airborne Observatory. This telescope is designed for infrared astronomy observations in the stratosphere at altitudes of about 12 kilometres, SOFIAs flight capability allows it to rise above almost all of the water vapor in the Earths atmosphere, which blocks some infrared wavelengths from reaching the ground. At the aircrafts cruising altitude, 85% of the infrared range will be available. The aircraft can travel to almost any point on the Earths surface. Once ready for use, observing flights were expected to be three or four nights a week. SOFIA uses a 2.5 m reflector telescope, which has an oversized,2.7 m diameter primary mirror, the optical system uses a Cassegrain reflector design with a parabolic primary mirror and a remotely configurable hyperbolic secondary. In order to fit the telescope into the fuselage, the primary is shaped to an f-number as low as 1.3, a flat, tertiary, dichroic mirror is used to deflect the infrared part of the beam to the Nasmyth focus where it can be analyzed. An optical mirror located behind the mirror is used for a camera guidance system. 3–1.1 μm. The main instruments are the FLITECAM, an infrared camera covering 1–5 μm, FORCAST, covering the mid-infrared range of 5–40 μm, and HAWC. The other four instruments include an optical photometer and infrared spectrometers with various spectral ranges, sOFIA’s telescope is by far the largest ever to be placed in an aircraft. For each mission one interchangeable science instrument will be attached to the telescope, two groups of general purpose instruments are available. In addition an investigator can also design and build a special purpose instrument, the open cavity housing the telescope will be exposed to high-speed turbulent winds. In addition, the vibrations and motions of the aircraft introduce observing difficulties, the telescope was designed to be very lightweight, with a honeycomb shape milled into the back of the mirror and polymer composite material used for the telescope assembly. The mount includes a system of bearings in pressurized oil to isolate the instrument from vibration, tracking is achieved through a system of gyroscopes, high speed cameras, and magnetic torque motors to compensate for motion, including vibrations from airflow and the aircraft engines. The telescope cabin must be cooled prior to aircraft takeoff to ensure the telescope matches the temperature to prevent thermally induced shape changes. Prior to landing the compartment is flooded with gas to prevent condensation of moisture on the chilled optics
31.
Submillimeter Wave Astronomy Satellite
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The Submillimeter Wave Astronomy Satellite is a NASA submillimeter astronomy satellite, and is the third spacecraft in the Small Explorer program. It was launched on December 6,1998, from Vandenberg Air Force Base aboard a Pegasus XL rocket, the telescope was designed by the Smithsonian Astrophysical Observatory and integrated by Ball Aerospace, while the spacecraft was built by NASAs Goddard Space Flight Center. The missions principal investigator is Gary J. Melnick, SWAS was designed to study the composition and structure of interstellar clouds and investigate the processes of stellar and planetary formation. Its sole instrument is an operating in the submillimeter wavelengths of far infrared. The telescope is composed of three components, a 55 ×71 cm elliptical off-axis Cassegrain reflector, two Schottky diode receivers, and an acousto-optical spectrometer. The Submillimeter Wave Astronomy Satellite mission was approved on April 1,1989, the project began with the Mission Definition Phase, officially starting on September 29,1989, and running through January 31,1992. The missions Development Phase ran from February 1992, through May 1996, the Submillimeter Wave Telescope underwent a preliminary design review on May 13,1992, and a critical design review on February 23,1993. Ball Aerospace was responsible for the construction of and integration of components into the telescope, Ball delivered the finished telescope to Goddard Space Flight Center on December 20,1994. Goddard, which was responsible for construction of the bus, conducted integration of spacecraft. Spacecraft qualification and testing took place between April 1,1995, and December 15,1995, after this, SWAS was placed into storage until September 1,1998, when launch preparation was begun. The spacecraft was delivered to Orbital Sciences Corporation at Vandenberg Air Force Base on November 2,1998, launch occurred on December 6,1998, at 00,57 UTC, from Orbital Sciences Stargazer L-1011 TriStar mothership. Its initial orbit was a near-circular 638 ×651 km with an inclination of 69.9 degrees, SWAS was originally scheduled to launch in June 1995, but was delayed due to back-to-back launch failures of the Pegasus XL rocket in June 1994 and June 1995. A launch opportunity in January 1997 was again canceled due to a Pegasus XL launch failure in November 1996, the commissioning phase of the mission lasted until December 19,1998, when the telescope began producing useful science data. The SWAS mission had a duration of two years and a cost estimate of US$60 million, but mission extensions allowed for five. During this time, data was taken on more than 200 astronomical objects, the decision was made to end science and spacecraft operations on July 21,2004, at which time the spacecraft was placed into hibernation. To support the Deep Impact mission at comet 9P/Tempel, SWAS was brought out of hibernation on June 1,2005, vehicle check-out was completed on June 5 with no discernible degradation of equipment found. SWAS observations of the focused on isotopic water output both before and after the Deep Impact impactor struck the comets nucleus on July 4. While water output was found to vary by more than a factor of three during the observation campaign, SWAS data showed that there was no excessive release of water due to the impact event
32.
Herschel Space Observatory
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The Herschel Space Observatory was a space observatory built and operated by the European Space Agency. It was active from 2009 to 2013, and was the largest infrared telescope ever launched, carrying a single 3. 5-metre mirror and instruments sensitive to the far infrared and submillimetre wavebands. Herschel was the fourth and final mission in the Horizon 2000 programme, following SOHO/Cluster II, XMM-Newton. The observatory was carried into orbit in May 2009, reaching the second Lagrangian point of the Earth–Sun system,1,500,000 kilometres from Earth, about two months later. Herschel is named after Sir William Herschel, the discoverer of the spectrum and planet Uranus. The observatory was capable of seeing the coldest and dustiest objects in space, for example, cool cocoons where stars form, the observatory sifted through star-forming clouds—the slow cookers of star ingredients—to trace the path by which potentially life-forming molecules, such as water, form. The telescopes lifespan was governed by the amount of coolant available for its instruments, when that coolant ran out, at the time of its launch, operations were estimated to last 3.5 years. It continued to operate until 29 April 201315,20 UTC, in 1982 the Far Infrared and Sub-millimetre Telescope was proposed to ESA. The ESA long-term policy-plan Horizon 2000, produced in 1984, called for a High Throughput Heterodyne Spectroscopy mission as one of its cornerstone missions, in 1986, FIRST was adopted as this cornerstone mission. It was selected for implementation in 1993, following a study in 1992–1993. The mission concept was redesigned from Earth-orbit to the Lagrangian point L2, in 2000, FIRST was renamed Herschel. After being put out to tender in 2000, industrial activities began in 2001, as of 2010, the Herschel mission is estimated to cost 1,100 million €. This figure includes spacecraft and payload, launch and mission expenses, during the mission, Herschel made over 35,000 scientific observations and amass more than 25,000 hours worth of science data from about 600 different observing programs. The mission involved the first space observatory to cover the far infrared. At 3.5 metres wide, Herschel carried the largest optical telescope ever deployed in space and it was made not from glass but from sintered silicon carbide. The light reflected by the mirror was focused onto three instruments, whose detectors were kept at temperatures below 2 K, the instruments were cooled with over 2,300 litres of liquid helium, boiling away in a near vacuum at a temperature of approximately 1.4 K. The supply of helium on board the spacecraft was a limit to the operational lifetime of the space observatory. Herschel carried three detectors, PACS An imaging camera and low-resolution spectrometer covering wavelengths from 55 to 210 micrometres, the spectrometer had a spectral resolution between R=1000 and R=5000 and was able to detect signals as weak as −63 dB
33.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
34.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
35.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
36.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
37.
Deep Impact (spacecraft)
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Deep Impact was a NASA space probe launched from Cape Canaveral Air Force Station at 18,47 UTC on January 12,2005. It was designed to study the composition of the comet Tempel 1. At 05,52 UTC on July 4,2005, the impactor successfully collided with the comets nucleus, the impact excavated debris from the interior of the nucleus, forming an impact crater. Photographs taken by the spacecraft showed the comet to be more dusty, the impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater. Previous space missions to comets, such as Giotto and Stardust, were fly-by missions and these missions were able to photograph and examine only the surfaces of cometary nuclei, and even then from considerable distances. The Deep Impact mission was the first to eject material from a surface, and the mission garnered large publicity from the media, international scientists. Upon the completion of its mission, proposals were made to further utilize the spacecraft. Consequently, Deep Impact flew by Earth on December 31,2007 on its way to a mission, designated EPOXI, with a dual purpose to study extrasolar planets. By observing the composition of the comet, astronomers hoped to determine how comets form based on the differences between the interior and exterior makeup of the comet, observations of the impact and its aftermath would allow astronomers to attempt to determine the answers to these questions. The missions Principal Investigator was Michael AHearn, an astronomer at the University of Maryland, the Flyby spacecraft is about 3.2 meters long,1.7 meters wide and 2.3 meters high. It includes two panels, a debris shield, and several science instruments for imaging, infrared spectroscopy. The spacecraft also carried two cameras, the High Resolution Imager, and the Medium Resolution Imager.05 to 4.8 micrometres and it has been optimized for observing the comets nucleus. The MRI is the device, and was used primarily for navigation during the final 10-day approach. It also has a wheel, with a slightly different set of filters. The Impactor section of the spacecraft contains an instrument that is identical to the MRI, called the Impactor Targeting Sensor. Its dual purpose was to sense the Impactors trajectory, which could then be adjusted up to four times between release and impact, and to image the comet from close range, the final image taken by the impactor was snapped only 3.7 seconds before impact. The impactors payload, dubbed the Cratering Mass, was 100% copper, including this cratering mass, copper formed 49% of total mass of the impactor, this was to minimize interference with scientific measurements. Since copper was not expected to be found on a comet, instead of using explosives, it was also cheaper to use copper as the payload
38.
European Space Agency
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The European Space Agency is an intergovernmental organisation of 22 member states, dedicated to the exploration of space. Established in 1975 and headquartered in Paris, France, ESA has a staff of about 2,000. The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching, after World War II, many European scientists left Western Europe in order to work with the United States. The meeting was attended by representatives from eight countries, including Harrie Massey. The Western European nations decided to have two different agencies, one concerned with developing a system, ELDO, and the precursor of the European Space Agency. The latter was established on 20 March 1964 by an agreement signed on 14 June 1962, from 1968 to 1972, ESRO launched seven research satellites. ESA in its current form was founded with the ESA Convention in 1975, ESA has 10 founding member states, Belgium, Denmark, France, Germany, Italy, the Netherlands, Spain, Sweden, Switzerland and the United Kingdom. These signed the ESA Convention in 1975 and deposited the instruments of ratification by 1980, during this interval the agency functioned in a de facto fashion. ESA launched its first major scientific mission in 1975, Cos-B, ESA joined NASA in the IUE, the worlds first high-orbit telescope, which was launched in 1978 and operated very successfully for 18 years. A number of successful Earth-orbit projects followed, and in 1986 ESA began Giotto, its first deep-space mission, to study the comets Halley and Grigg–Skjellerup. Hipparcos, a mission, was launched in 1989 and in the 1990s SOHO, Ulysses. Recent scientific missions in co-operation with NASA include the Cassini–Huygens space probe, as the successor of ELDO, ESA has also constructed rockets for scientific and commercial payloads. Ariane 1, launched in 1979, brought mostly commercial payloads into orbit from 1984 onward, the successor launch vehicle of Ariane 5, the Ariane 6 is already in the definition stage and is envisioned to enter service in the 2020s. The beginning of the new millennium saw ESA become, along with agencies like NASA, JAXA, ISRO, CSA and Roscosmos, one of the major participants in scientific space research. Although ESA had relied on co-operation with NASA in previous decades, especially the 1990s, changed circumstances led to decisions to rely more on itself, a 2011 press issue thus stated, Russia is ESAs first partner in its efforts to ensure long-term access to space. ESA maintains its scientific and research projects mainly for astronomy-space missions such as Corot, launched on 27 December 2006 and this is the reason space exploration is an integral part of overall space activities. It has always been so, and it will be more important in the future. ESA describes its work in two overlapping ways, For the general public the various fields of work are described as Activities, Member states participate to varying degrees in the mandatory and optional space programmes
39.
Lissajous orbit
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Lyapunov orbits around a Lagrangian point are curved paths that lie entirely in the plane of the two primary bodies. In contrast, Lissajous orbits include components in this plane and perpendicular to it, halo orbits also include components perpendicular to the plane, but they are periodic, while Lissajous orbits are not. In practice, any orbits around Lagrangian points L1, L2, or L3 are dynamically unstable, as a result, spacecraft in these Lagrangian point orbits must use their propulsion systems to perform orbital station-keeping. These orbits can however be destabilized by other nearby massive objects, several missions have used Lissajous orbits, ACE at Sun–Earth L1, SOHO at Sun-Earth L1, DSCOVR at Sun–Earth L1, WMAP at Sun–Earth L2, and also the Genesis mission collecting solar particles at L1. On 14 May 2009, the European Space Agency launched into space the Herschel and Planck observatories, eSAs current Gaia mission also uses a Lissajous orbit at Sun–Earth L2. In 2011, NASA transferred two of its THEMIS spacecraft from Earth orbit to Lunar orbit by way of Earth-Moon L1 and L2 Lissajous orbits. In the 2005 science fiction novel Sunstorm by Arthur C. Clarke and Stephen Baxter, the shield is described to have been in a Lissajous orbit at L1. In the story a group of wealthy and powerful people shelter opposite the shield at L2 so as to be protected from the storm by the shield, the Earth. Koon, W. S. M. W. Lo, J. E. Marsden, dynamical Systems, the Three-Body Problem, and Space Mission Design
40.
Lagrangian point
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The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centrifugal force required to orbit with them. There are five points, labeled L1 to L5, all in the orbital plane of the two large bodies. The first three are on the line connecting the two bodies, the last two, L4 and L5, each form an equilateral triangle with the two large bodies. The two latter points are stable, which implies that objects can orbit around them in a coordinate system tied to the two large bodies. Several planets have satellites near their L4 and L5 points with respect to the Sun, the three collinear Lagrange points were discovered by Leonhard Euler a few years before Lagrange discovered the remaining two. In 1772, Joseph-Louis Lagrange published an Essay on the three-body problem, in the first chapter he considered the general three-body problem. From that, in the chapter, he demonstrated two special constant-pattern solutions, the collinear and the equilateral, for any three masses, with circular orbits. The five Lagrangian points are labeled and defined as follows, The L1 point lies on the line defined by the two large masses M1 and M2, and between them. It is the most intuitively understood of the Lagrangian points, the one where the attraction of M2 partially cancels M1s gravitational attraction. Explanation An object that orbits the Sun more closely than Earth would normally have an orbital period than Earth. If the object is directly between Earth and the Sun, then Earths gravity counteracts some of the Suns pull on the object, the closer to Earth the object is, the greater this effect is. At the L1 point, the period of the object becomes exactly equal to Earths orbital period. L1 is about 1.5 million kilometers from Earth, the L2 point lies on the line through the two large masses, beyond the smaller of the two. Here, the forces of the two large masses balance the centrifugal effect on a body at L2. Explanation On the opposite side of Earth from the Sun, the period of an object would normally be greater than that of Earth. The extra pull of Earths gravity decreases the orbital period of the object, like L1, L2 is about 1.5 million kilometers from Earth. The L3 point lies on the line defined by the two masses, beyond the larger of the two. Explanation L3 in the Sun–Earth system exists on the side of the Sun
41.
Submillimetre Common-User Bolometer Array
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Two instruments known as the Submillimetre Common-User Bolometer Array, or SCUBA, have been used for detecting submillimetre radiation on the James Clerk Maxwell Telescope in Hawaii. The older continuum single pixel UKT14 bolometer receiver was replaced in the 1990s by the Submillimeter Common-User Bolometer Array, the SCUBA project was green-lighted in 1987 by the JCMT board and was in development for nearly a decade before it saw first light on the telescope. While it was not the first bolometer array it was unique in combining an unparallel sensitivity with a wavelength range. SCUBA operated simultaneously at wavelengths of 450 and 850 micron, and was sensitive to the emission from interstellar dust. SCUBA is ranked second only to the Hubble Space Telescope in terms of publication of high-impact astronomical research, SCUBA was retired from service in 2005, and it is now in the National Museum of Scotland in Edinburgh. SCUBA-2, another instrument, was commissioned in 2011. This ground-breaking camera consists of arrays of superconducting transition edge sensors with a mapping speed hundreds of times larger than SCUBA. It has 5120 array elements at both 450 and 850 micron wavelength and it has been conducting the JCMT legacy surveys since November,2011, including the SCUBA-2 All Sky Survey, and was made available for general astronomical observations in February,2012. Two ancillary instruments, FTS-2 and POL-2, add spectroscopic and polarimetric capabilities to SCUBA-2, the SCUBA-2 All-Sky Survey, is an astronomical survey using the SCUBA-2 camera to map the sky at submillimeter wavelengths. It is most sensitive to cold gas and dust. A team of around 50 astronomers from the United Kingdom, Canada, the United States, Netherlands, and Japan aim to map a huge swathe of the sky to find rare galaxies and stars being formed. The survey will achieve a resolution of 14 arcseconds,1800 times more detailed than the best previous full-sky map in the sub-mm from COBE. Despite its name, the project will not be able to map the southern-most areas of the sky that are not visible from the James Clerk Maxwell Telescope in Hawaii, sASSy is one of the major legacy surveys on the James Clerk Maxwell Telescope. It is the second-largest such legacy survey in terms of time on this telescope, the project seeks to answer the following questions, Is there an undiscovered population of extreme luminosity galaxies. What are the counts of bright sub-mm galaxies. What is the fraction of lens sub-mm sources, is there an undiscovered population of cold local galaxies. How many infrared dark clouds are there in our Galaxy and how are they distributed, what is the relation of infrared dark clouds to star formation and Galactic structure. Is there an unknown population of star formation
42.
Infrared window
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A large gap in the absorption spectrum of water vapor, the main greenhouse gas, is most important in the dynamics of the window. Other gases, especially carbon dioxide and ozone, partly block transmission, window radiation is radiation that actually passes through the atmospheric window. Non-window radiation is radiation that actually does not pass through the atmospheric window, window wavelength radiation is radiation that, judging only from its wavelength, potentially might or might not, but is likely to pass through the atmospheric window. Non-window wavelength radiation is radiation that, judging only from its wavelength, is unlikely to pass through the atmospheric window. In those days, computers were not available, and Simpson notes that he used approximations, he writes, There is no hope of getting an exact solution, nowadays, accurate line-by-line computations are possible, and careful studies of the infrared atmospheric window have been published. The infrared atmospheric window is a path from the surface of the earth to space. It separates two components, window and non-window radiation, that are not of the kind that have kinetics suitable for description by the Beer-Lambert law. The window radiation and the radiation from the land-sea surface are not defined in the terms that are necessary for the application of the Beer-Lambert Law. It would therefore be a logical and conceptual error to try to apply the Beer-Lambert Law either to window or non-window radiation considered separately. The reason for this is that the window and non-window radiation have already been conditioned by the Beer-Lambert Law, logically, the Beer-Lambert Law applies to radiation of which the origin is known but the destination is unknown. Such is not the case for window and non-window radiation, thus it makes sense to state the precise spectral distribution and spatial, especially altitudinal, distribution of locations of absorption of non-window radiation in the atmosphere. Radiation that can be described by the Beer-Lambert Law can partly escape absorption by the medium of interest, non-window radiation is by definition absorbed by the atmosphere, and its energy is thereby transduced into kinetic energy of atmospheric molecules. That kinetic energy is then transferred according to the dynamics of atmospheric energy transfer. The infrared absorptions of the natural greenhouse gases are mostly in two ranges. At wavelengths longer than 14 µm, gases such as CO2 and CH4 absorb due to the presence of relatively long C-H and carbonyl bonds, the bonds of H2O and NH3 absorb at wavelengths shorter than 8 µm. Clouds are excellent emitters of infrared radiation, moreover, the water vapour continuum absorptivity, molecule for molecule, decreases with pressure decrease. Thus water vapour above the clouds, besides being less concentrated, is also less absorptive than water vapour at lower altitudes. Without the infrared atmospheric window, the Earth would become too warm to support life
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