Gran Telescopio Canarias
The Gran Telescopio Canarias is a 10.4 m reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain. Construction of the telescope cost € 130 million, its installation had been hampered by weather conditions and the logistical difficulties of transporting equipment to such a remote location. First light was achieved in 2007 and scientific observations began in 2009; the GTC Project is a partnership formed by several institutions from Spain and Mexico, the University of Florida, the National Autonomous University of Mexico, the Instituto de Astrofísica de Canarias. Planning for the construction of the telescope, which started in 1987, involved more than 1,000 people from 100 companies, it is the world's largest single-aperture optical telescope. The division of telescope time reflects the structure of its financing: 90% Spain, 5% Mexico and 5% the University of Florida; the GTC began its preliminary observations on 13 July 2007, using 12 segments of its primary mirror, made of Zerodur glass-ceramic by the German company Schott AG.
The number of segments was increased to a total of 36 hexagonal segments controlled by an active optics control system, working together as a reflective unit. Its Day One instrumentation was OSIRIS. Scientific observations began properly in May 2009; the Gran Telescopio Canarias formally opened its shutters on July 24, 2009, inaugurated by King Juan Carlos I of Spain. More than 500 astronomers, government officials and journalists from Europe and the Americas attended the ceremony. MEGARA is an optical integral-field and multi-object spectrograph covering the visible light and near infrared wavelength range between 0.365 and 1 µm with a spectral resolution in the range R=6000-20000. The MEGARA IFU offers a contiguous field of view of 12.5 arcsec x 11.3 arcsec, while the multiobject spectroscopy mode allows observing 92 objects in a field of view of 3.5 arcmin x 3.5 arcmin by means of an equal number of robotic positioners. Both the LCB and MOS modes make use of 100 µm-core optical fibers that are attached to a set of microlens arrays with each microlens covering an hexagonal region of 0.62 arcsec in diameter.
The University of Florida's CanariCam is a mid-infrared imager with spectroscopic and polarimetric capabilities, which will be mounted at the Nasmyth focus of the telescope. In the future, when the Cassegrain focus of the telescope is commissioned, it is expected that CanariCam will move to this focus, which will provide superior performance with the instrument. CanariCam is designed as a diffraction-limited imager, it is optimized as an imager, although it will offer a range of other observing modes, these will not compromise the imaging capability. The fact that CanariCam offers polarimetry and coronagraphy in addition to the more standard imaging and spectroscopic modes makes it a versatile and powerful instrument. CanariCam will work in the thermal infrared between 7.5 and 25 μm. At the short wavelength end, the cut-off is determined by the atmosphere—specifically atmospheric seeing. At the long wavelength end, the cut-off is determined by the detector. CanariCam is a compact design, it is expected that the total weight of the cryostat and its on-telescope electronics will be under 400 kg.
Most previous mid-infrared instruments have used liquid helium as a cryogen. CanariCam will use a two-stage closed cycle cryocooler system to cool the cold optics and cryostat interior down to 28 K, the detector itself to around 8 K, the temperature at which the detector works most efficiently. CanariCam is operational as of December 3rd, 2009; the IAC's OSIRIS, is an "imaging and low resolution spectrograph with longslit and multiobject spectroscopic modes. It covers the wavelength range from 0.365 to 1.05 µm with a field of views of 7 × 7 arcmin, 8 arcmin × 5.2 arcmin, for direct imaging and low resolution spectroscopy respectively." It "provides a new generation of instrumental observation techniques such as the tunable filters, the charge-shuffling capability in the CCD detectors, etc." Other observatory sites La Silla Observatory Mauna Kea Observatories Paranal Observatory Lists and comparisons Extremely large telescope List of largest optical reflecting telescopes List of largest optical telescopes Gran Telescopio Canarias GTC News Instituto de Astrofísica de Canarias University of Florida CanariCam Consejo Nacional de Ciencia y Tecnología de México Instituto de Astronomía de la Universidad Nacional Autónoma de México CBC article—Giant Canary Islands telescope captures first light Images Gran Telescopo Canarias inauguration press dossier Merrifield, Michael.
"Gran Telescopio Canarias". Deep Sky Videos. Brady Haran
Reflecting telescope
A reflecting telescope is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century, by Isaac Newton, as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for large diameter objectives. All of the major telescopes used in astronomy research are reflectors. Reflecting telescopes come in many design variations and may employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a "catoptric" telescope; the idea that curved mirrors behave like lenses dates back at least to Alhazen's 11th century treatise on optics, works, disseminated in Latin translations in early modern Europe. Soon after the invention of the refracting telescope, Giovanni Francesco Sagredo, others, spurred on by their knowledge of the principles of curved mirrors, discussed the idea of building a telescope using a mirror as the image forming objective.
There were reports that the Bolognese Cesare Caravaggi had constructed one around 1626 and the Italian professor Niccolò Zucchi, in a work, wrote that he had experimented with a concave bronze mirror in 1616, but said it did not produce a satisfactory image. The potential advantages of using parabolic mirrors reduction of spherical aberration with no chromatic aberration, led to many proposed designs for reflecting telescopes; the most notable being James Gregory, who published an innovative design for a ‘reflecting’ telescope in 1663. It would be ten years, before the experimental scientist Robert Hooke was able to build this type of telescope, which became known as the Gregorian telescope. Isaac Newton has been credited with building the first reflecting telescope in 1668, it used a spherically ground metal primary mirror and a small diagonal mirror in an optical configuration that has come to be known as the Newtonian telescope. Despite the theoretical advantages of the reflector design, the difficulty of construction and the poor performance of the speculum metal mirrors being used at the time meant it took over 100 years for them to become popular.
Many of the advances in reflecting telescopes included the perfection of parabolic mirror fabrication in the 18th century, silver coated glass mirrors in the 19th century, long-lasting aluminum coatings in the 20th century, segmented mirrors to allow larger diameters, active optics to compensate for gravitational deformation. A mid-20th century innovation was catadioptric telescopes such as the Schmidt camera, which use both a spherical mirror and a lens as primary optical elements used for wide-field imaging without spherical aberration; the late 20th century has seen the development of adaptive optics and lucky imaging to overcome the problems of seeing, reflecting telescopes are ubiquitous on space telescopes and many types of spacecraft imaging devices. A curved primary mirror is the reflector telescope's basic optical element that creates an image at the focal plane; the distance from the mirror to the focal plane is called the focal length. Film or a digital sensor may be located here to record the image, or a secondary mirror may be added to modify the optical characteristics and/or redirect the light to film, digital sensors, or an eyepiece for visual observation.
The primary mirror in most modern telescopes is composed of a solid glass cylinder whose front surface has been ground to a spherical or parabolic shape. A thin layer of aluminum is vacuum deposited onto the mirror, forming a reflective first surface mirror; some telescopes use primary mirrors. Molten glass is rotated to make its surface paraboloidal, is kept rotating while it cools and solidifies; the resulting mirror shape approximates a desired paraboloid shape that requires minimal grinding and polishing to reach the exact figure needed. Reflecting telescopes, just like any other optical system, do not produce "perfect" images; the need to image objects at distances up to infinity, view them at different wavelengths of light, along with the requirement to have some way to view the image the primary mirror produces, means there is always some compromise in a reflecting telescope's optical design. Because the primary mirror focuses light to a common point in front of its own reflecting surface all reflecting telescope designs have a secondary mirror, film holder, or detector near that focal point obstructing the light from reaching the primary mirror.
Not only does this cause some reduction in the amount of light the system collects, it causes a loss in contrast in the image due to diffraction effects of the obstruction as well as diffraction spikes caused by most secondary support structures. The use of mirrors avoids chromatic aberration but they produce other types of aberrations. A simple spherical mirror cannot bring light from a distant object to a common focus since the reflection of light rays striking the mirror near its edge do not converge with those that reflect from nearer the center of the mirror, a defect called spherical aberration. To avoid this problem most reflecting telescopes use parabolic shaped mirrors, a shape that can focus all the light to a common focus. Parabolic mirrors work well with objects near the center of the image they produce, but towards the edge of that same field of view they suffer from off axis aberrations: Coma - an aberr
Diffraction
Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. It is defined as the bending of waves around the corners of an obstacle or aperture into the region of geometrical shadow of the obstacle. In classical physics, the diffraction phenomenon is described as the interference of waves according to the Huygens–Fresnel principle that treats each point in the wave-front as a collection of individual spherical wavelets; these characteristic behaviors are exhibited when a wave encounters an obstacle or a slit, comparable in size to its wavelength. Similar effects occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance. Diffraction has an impact on the acoustic space. Diffraction occurs with all waves, including sound waves, water waves, electromagnetic waves such as visible light, X-rays and radio waves. Since physical objects have wave-like properties, diffraction occurs with matter and can be studied according to the principles of quantum mechanics.
Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1660. While diffraction occurs whenever propagating waves encounter such changes, its effects are most pronounced for waves whose wavelength is comparable to the dimensions of the diffracting object or slit. If the obstructing object provides multiple spaced openings, a complex pattern of varying intensity can result; this is due to the addition, or interference, of different parts of a wave that travel to the observer by different paths, where different path lengths result in different phases. The formalism of diffraction can describe the way in which waves of finite extent propagate in free space. For example, the expanding profile of a laser beam, the beam shape of a radar antenna and the field of view of an ultrasonic transducer can all be analyzed using diffraction equations; the effects of diffraction are seen in everyday life. The most striking examples of diffraction are those.
This principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired. Diffraction in the atmosphere by small particles can cause a bright ring to be visible around a bright light source like the sun or the moon. A shadow of a solid object, using light from a compact source, shows small fringes near its edges; the speckle pattern, observed when laser light falls on an optically rough surface is a diffraction phenomenon. When deli meat appears to be iridescent, diffraction off the meat fibers. All these effects are a consequence of the fact. Diffraction can occur with any kind of wave. Ocean waves diffract around other obstacles. Sound waves can diffract around objects, why one can still hear someone calling when hiding behind a tree. Diffraction can be a concern in some technical applications; the effects of diffraction of light were first observed and characterized by Francesco Maria Grimaldi, who coined the term diffraction, from the Latin diffringere,'to break into pieces', referring to light breaking up into different directions.
The results of Grimaldi's observations were published posthumously in 1665. Isaac Newton attributed them to inflexion of light rays. James Gregory observed the diffraction patterns caused by a bird feather, the first diffraction grating to be discovered. Thomas Young performed a celebrated experiment in 1803 demonstrating interference from two spaced slits. Explaining his results by interference of the waves emanating from the two different slits, he deduced that light must propagate as waves. Augustin-Jean Fresnel did more definitive studies and calculations of diffraction, made public in 1815 and 1818, thereby gave great support to the wave theory of light, advanced by Christiaan Huygens and reinvigorated by Young, against Newton's particle theory. In traditional classical physics diffraction arises because of the way; the propagation of a wave can be visualized by considering every particle of the transmitted medium on a wavefront as a point source for a secondary spherical wave. The wave displacement at any subsequent point is the sum of these secondary waves.
When waves are added together, their sum is determined by the relative phases as well as the amplitudes of the individual waves so that the summed amplitude of the waves can have any value between zero and the sum of the individual amplitudes. Hence, diffraction patterns have a series of maxima and minima. In the modern quantum mechanical understanding of light propagation through a slit every photon has what is known as a wavefunction which describes its path from the emitter through the slit to the screen; the wavefunction is determined by the physical surroundings such as slit geometry, screen distance and initial conditions when the photon is created. In important experiments the existence of the photon's wavef
South African Astronomical Observatory
South African Astronomical Observatory is the national centre for optical and infrared astronomy in South Africa. It was established in 1972; the observatory is run by the National Research Foundation of South Africa. The facility's function is to conduct research in astronomy and astrophysics; the primary telescopes are located in Sutherland, 370 kilometres from Observatory, Cape Town, where the headquarters is located. The SAAO has links worldwide for technological collaboration. Instrumental contributions from the South African Astronomical Observatory include the development of a spherical aberration corrector and the Southern African Large Telescope; the Noon Gun on Cape Town's Signal Hill is fired remotely by a time signal from the Observatory. The history of the SAAO began when the Royal Observatory at the Cape of Good Hope was founded in 1820, the first scientific institution in Africa. Construction of the main buildings was completed in 1829 at a cost of £30,000; the post of Her Majesty's astronomer at the Cape of Good Hope was awarded the Royal Medal on two occasions.
The Republic Observatory, was merged with the much older Royal Observatory, Cape of Good Hope in January 1972 to form the South African Astronomical Observatory. In 1974 the Radcliffe Observatory telescope was purchased by the CSIR and moved to Sutherland, where it recommenced work in 1976. SAAO was established in January 1972, as a result of a joint agreement by the Council for Scientific and Industrial Research of South Africa and Science and Engineering Research Council of United Kingdom; the headquarters are located on the grounds of the old Royal Observatory where the main building, national library for astronomy and computer facilities are housed. Historic telescopes are found at the headquarters in a number of domes and a small museum that displays scientific instruments; the South African Astronomical Observatory is administered at present as a National Facility under management of the National Research Foundation the Foundation for Research Development. In 1974, when the Radcliffe Observatory in Pretoria closed, the Council for Scientific and Industrial Research purchased the 1.9 m Radcliffe telescope and transported it to Sutherland.
The observatory operates from the campus of the Royal Observatory, Cape of Good Hope, established in 1820 in the suburb of Observatory, Cape Town. The major observing facilities are however located near the town of Sutherland some 370 kilometres from Cape Town; this 0.5 metres reflector was built for the Republic Observatory in 1967, but was moved to the Sutherland site in 1972. A 0.75 metres Grubb Parsons reflector. This 40 inches telescope was located at SAAO Head office in Observatory, Cape Town, but has since moved to the Sutherland site; this telescope participates in the PLANET network. The 1.9m Radcliffe Telescope was commissioned for the Radcliffe Observatory in Pretoria where it was in use between 1948 and 1974. Following the closure of the Radcliffe Observatory it was moved to Sutherland where it became operational again in January 1976. Between 1951 and 2004 it was the largest telescope in South Africa; the telescope was manufactured by Sir Howard Parsons and Co.. This 29.5 inches telescope was called the Automatic Photometric Telescope, but has been renamed the Alan Cousins Telescope in honour of Alan William James Cousins.
One of six telescopes in the Birmingham Solar Oscillations Network The IRSF is a 140 centimetres reflector fitted with a 3 colour Infrared Imager. Built as part of the Magellanic Clouds – A Thorough Study grant from the Japanese Ministry of Education, Sports and Technology in 2000. Other studies the telescope participated in include: The Indian Department of Space used this telescope for the Near Infrared Survey of the Nuclear Regions of the Milky Way to improve on data from the DENIS and 2MASS Astronomical surveys. Three 1 metre telescopes to form part of the LCOGT network were installed in early 2013; the MASTER-SAAO Telescope is part of the Russian Mobile Astronomical System of Telescope-Robots. It saw first light on 21 December 2014, it consists of two paired 0.4-m telescopes. In April 2015 it discovered the first comet from South Africa in 35 years, C/2015 G2. One of the two 1.20 metres telescopes of the MOnitoring NEtwork of Telescopes Project is located at Sutherland. Its twin can be found at the McDonald Observatory in Texas.
The MONET telescopes are Robotic telescope controllable via the Internet and was constructed by the University of Göttingen. Remote Telescope Markup Language is used to control the telescopes remotely. Two telescopes forming part of Project Solaris is located at the Sutherland site. Solaris-1 and Solaris-2 are both 0.5m f/15 Ritchey–Chrétien telescope. The aims of Project Solaris is to detect circumbinary planets around eclipsing binary stars and to characterise these binaries to improve stellar models. Observatory Code: B31 Observations: SALT was inaugurated in November 2005, it is the largest single optical telescope in the Southern Hemisphere, with a hexagonal mirror array 11 meters across. SALT shares similarities with the Hobby-Eberly Telescope in Texas; the Southern African Large Telescope gathers twenty-five times as much light as any other existing African Telescope. With this larger mirror array
Gold
Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric
Cryogenics
In physics, cryogenics is the production and behaviour of materials at low temperatures. A person who studies elements that have been subjected to cold temperatures is called a cryogenicist, it is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below −150 °C. The U. S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C; this is a logical dividing line, since the normal boiling points of the so-called permanent gases lie below −180 °C while the Freon refrigerants and other common refrigerants have boiling points above −180 °C. Discovery of superconducting materials with critical temperatures above the boiling point of liquid nitrogen has provided new interest in reliable, low cost methods of producing high temperature cryogenic refrigeration; the term "high temperature cryogenic" describes temperatures ranging from above the boiling point of liquid nitrogen, −195.79 °C, up to −50 °C, the defined upper limit of study referred to as cryogenics.
Cryogenicists use the Kelvin or Rankine temperature scale, both of which measure from absolute zero, rather than more usual scales such as Celsius or Fahrenheit, with their zeroes at arbitrary temperatures. Cryogenics The branches of engineering that involve the study of low temperatures, how to produce them, how materials behave at those temperatures. Cryobiology The branch of biology involving the study of the effects of low temperatures on organisms. Cryoconservation of animal genetic resources The conservation of genetic material with the intention of conserving a breed. Cryosurgery The branch of surgery applying cryogenic temperatures to destroy malignant tissue, e.g. cancer cells. Cryoelectronics The study of electronic phenomena at cryogenic temperatures. Examples include variable-range hopping. Cryotronics The practical application of cryoelectronics. Cryonics Cryopreserving humans and animals with the intention of future revival. "Cryogenics" is sometimes erroneously used to mean "Cryonics" in the press.
The word cryogenics stems from Greek κρύο – "cold" + γονική – "having to do with production". Cryogenic fluids with their boiling point in kelvins. Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most used element in cryogenics and is purchasable around the world. Liquid helium is commonly used and allows for the lowest attainable temperatures to be reached; these liquids may be stored in Dewar flasks, which are double-walled containers with a high vacuum between the walls to reduce heat transfer into the liquid. Typical laboratory Dewar flasks are spherical, made of glass and protected in a metal outer container. Dewar flasks for cold liquids such as liquid helium have another double-walled container filled with liquid nitrogen. Dewar flasks are named after James Dewar, the man who first liquefied hydrogen. Thermos bottles are smaller vacuum flasks fitted in a protective casing. Cryogenic barcode labels are used to mark Dewar flasks containing these liquids, will not frost over down to −195 degrees Celsius.
Cryogenic transfer pumps are the pumps used on LNG piers to transfer liquefied natural gas from LNG carriers to LNG storage tanks, as are cryogenic valves. The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. With a background in the heat treating industry, Busch founded a company in Detroit called CryoTech in 1966 which merged with 300 Below in 1999 to become the world's largest and oldest commercial cryogenic processing company. Busch experimented with the possibility of increasing the life of metal tools to anywhere between 200% and 400% of the original life expectancy using cryogenic tempering instead of heat treating; this evolved in the late 1990s into the treatment of other parts. Cryogens, such as liquid nitrogen, are further used for specialty chilling and freezing applications.
Some chemical reactions, like those used to produce the active ingredients for the popular statin drugs, must occur at low temperatures of −100 °C. Special cryogenic chemical reactors are used to remove reaction heat and provide a low temperature environment; the freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and brittle at low temperatures, which makes cryogenic milling an option for some materials that cannot be milled at higher temperatures. Cryogenic processing is not a substitute for heat treatment, but rather an extension of the heating–quenching–tempering cycle; when an item is quenched, the final temperature is ambient. The only reason for this is. There is nothing metallurgically significant about ambient temperature; the cryogenic process continues this action from ambient temperature down to −320 °F. In most instances the cryogenic cycle is followed by a heat tempering procedure.
As all alloys do not have the same chemical constituents, the tempering procedure varies according to the material's chemical composition, t
Ariane 5
Ariane 5 is a European heavy-lift launch vehicle, part of the Ariane rocket family, an expendable launch system designed by the Centre national d'études spatiales. It is used to deliver payloads into low Earth orbit; the Ariane project was instrumental in helping to overcome the European space crisis because Germans and French worked more together to develop the Ariane. Ariane 5 rockets are manufactured under the authority of the European Space Agency and the French spatial agency Centre National d'Etudes Spatiales. Airbus Defence and Space is the prime contractor for the vehicles, leading a consortium of other European contractors. Ariane 5 is marketed by Arianespace as part of the Ariane programme; the rockets are launched by Arianespace from the Guiana Space Centre in French Guiana. Ariane 5 succeeded Ariane 4, but was not derived from it directly as Ariane 5 was developed from scratch. Ariane 5 has been refined since the first launch in successive versions, "G", "G+", "GS", "ECA", most "ES".
ESA designed Ariane 5 to launch the Hermes spaceplane, thus intended it to be human rated from the beginning. Two satellites can be mounted using a SYLDA carrier. Three main satellites are possible depending on size using SPELTRA. Up to eight secondary payloads small experiment packages or minisatellites, can be carried with an ASAP platform; as of January 2018 Arianespace has signed contracts for Ariane 5 ECA launches up till 2022, after planned introduction of Ariane 6 in 2020. Ariane 5's cryogenic H173 main stage is called the EPC, it consists of a large tank 30.5 metres high with two compartments, one for liquid oxygen and one for liquid hydrogen, a Vulcain 2 engine at the base with a vacuum thrust of 1,390 kilonewtons. The H173 EPC weighs about 189 tonnes, including 175 tonnes of propellant. After the main cryogenic stage runs out of fuel, it re-enters the atmosphere for an ocean splashdown. Attached to the sides are two P241 solid rocket boosters, each weighing about 277 tonnes full and delivering a thrust of about 7,080 kilonewtons.
They are fueled by a mix of ammonium perchlorate and aluminum fuel and HTPB. They each burn for 130 seconds before being dropped into the ocean; the SRBs are allowed to sink to the bottom of the ocean, like the Space Shuttle Solid Rocket Boosters, they can be recovered with parachutes, this has been done for post-flight analysis. The most recent attempt was for the first Ariane 5 ECA mission. One of the two boosters was recovered and returned to the Guiana Space Center for analysis. Prior to that mission, the last such recovery and testing was done in 2003; the French M51 SLBM shares a substantial amount of technology with these boosters. In February 2000 the suspected nose cone of an Ariane 5 booster washed ashore on the South Texas coast, was recovered by beachcombers before the government could get to it; the second stage is below the payload. The Ariane 5 G used the EPS, fueled by monomethylhydrazine and nitrogen tetroxide, it has 10 tonnes of storable propellants. The EPS was improved for use on the Ariane 5 G+, GS, ES.
Ariane 5 ECA uses the ESC, fueled by liquid hydrogen and liquid oxygen. The EPS upper stage is capable of multiple ignitions, first demonstrated during flight V26, launched on 5 October 2007; this was purely to test the engine, occurred after the payloads had been deployed. The first operational use of restart capability as part of a mission came on 9 March 2008, when two burns were made to deploy the first Automated Transfer Vehicle into a circular parking orbit, followed by a third burn after ATV deployment to de-orbit the stage; this procedure was repeated for all subsequent ATV flights. The payload and all upper stages are covered at launch by a fairing, jettisoned once sufficient altitude has been reached; the fairing is used for aerodynamic stability and protection from heating during supersonic flight and acoustic loads. Launch system status: Retired · Cancelled · Operational · Under development As of November 2014, the Ariane 5 commercial launch price for launching a "midsize satellite in the lower position" is US$60 million, competing for commercial launches in an competitive market.
The heavier satellite launched in the upper position on a typical dual-satellite Ariane 5 launch is priced higher, on the order of €90 million. Total launch price of an Ariane 5—which can transport up to two satellites to space, one in the "upper" and one in the "lower" positions—is around 150 million Euro as of January 2015; the Ariane 5 ME was in development until 2015 and seen as a stopgap between Ariane 5 ECA/Ariane 5 ES and the new Ariane 6. With first flight planned for 2018, it would have become ESA's principal launcher until the arrival of the new Ariane 6 version; the Ariane 5 ME was to use a new upper stage, with increased propellant volume, powered by the new Vinci engine. Unlike the HM-7B engine, it was to be able restart several times, allowing for complex orbital maneuv
