document_title: Methane

question_text: methane is produced by the decomposition of what

question_tokens: methane is produced by the decomposition of what

text: Methane

text: History[edit]

text: This section needs expansion. You can help by adding to it. (November 2013)

text: In November 1776, methane was first scientifically identified by Italian physicist Alessandro Volta in the marshes of Lake Maggiore straddling Italy and Switzerland. Volta was inspired to search for the substance after reading a paper written by Benjamin Franklin about "flammable air".[7] Volta collected the gas rising from the marsh, and by 1778 had isolated the pure gas.[8] He also demonstrated that the gas could be ignited with an electric spark.[8]

text: The name "methane" was coined in 1866 by the German chemist August Wilhelm von Hofmann.[9] The name was derived from methanol.

text: Properties and bonding[edit]

text: Methane is a tetrahedral molecule with four equivalent C–H bonds. Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this energy level is a triply degenerate set of MOs that involve overlap of the 2p orbitals on carbon with various linear combinations of the 1s orbitals on hydrogen. The resulting "three-over-one" bonding scheme is consistent with photoelectron spectroscopic measurements.

text: At room temperature and standard pressure, methane is a colorless, odorless gas.[10] The familiar smell of natural gas as used in homes is achieved by the addition of an odorant, usually blends containing tert-butylthiol, as a safety measure. Methane has a boiling point of −161 °C (−257.8 °F) at a pressure of one atmosphere.[11] As a gas it is flammable over a range of concentrations (5.4–17%) in air at standard pressure.

text: Solid methane exists in several modifications. Presently nine are known.[12] Cooling methane at normal pressure results in the formation of methane I. This substance crystallizes in the cubic system (space group Fm3m). The positions of the hydrogen atoms are not fixed in methane I, i.e. methane molecules may rotate freely. Therefore, it is a plastic crystal.[13]

text: Chemical reactions[edit]

text: The primary chemical reactions of methane are combustion, steam reforming to syngas, and halogenation. In general, methane reactions are difficult to control. Partial oxidation to methanol, for example, is challenging because the reaction typically progresses all the way to carbon dioxide and water even with an insufficient supply of oxygen. The enzyme methane monooxygenase produces methanol from methane, but cannot be used for industrial-scale reactions.[14]

text: Acid-base reactions[edit]

text: Like other hydrocarbons, methane is a very weak acid. Its pKa in DMSO is estimated to be 56.[15] It cannot be deprotonated in solution, but the conjugate base with methyllithium is known.

text:
A variety of positive ions derived from methane have been observed, mostly as unstable species in low-pressure gas mixtures. These include methenium or methyl cation CH+
3, methane cation CH+
4, and methanium or protonated methane CH+
5. Some of these have been detected in outer space. Methanium can also be produced as diluted solutions from methane with superacids. Cations with higher charge, such as CH2+
6 and CH3+
7, have been studied theoretically and conjectured to be stable.[16]

text: Despite the strength of its C–H bonds, there is intense interest in catalysts that facilitate C–H bond activation in methane (and other lower numbered alkanes).[17]

text: Combustion[edit]

text: Methane's heat of combustion is 55.5 MJ/kg.[18] Combustion of methane is a multiple step reaction. The following equations are part of the process, with the net result being

text:
CH4+ M* → CH3 + H + M
CH4 + O2 → CH3 + HO2
CH4 + HO2 → CH3 + 2 OH
CH4 + OH → CH3 + H2O
O2 + H → O + OH
CH4 + O → CH3 + OH
CH3 + O2 → CH2O + OH
CH2O + O → CHO + OH
CH2O + OH → CHO + H2O
CH2O + H → CHO + H2
CHO + O → CO + OH
CHO + OH → CO + H2O
CHO + H → CO + H2
H2 + O → H + OH
H2 + OH → H + H2O
CO + OH → CO2 + H
H + OH + M → H2O + M*
H + H + M → H2 + M*
H + O2 + M → HO2 + M*

tag: ol

text:
The species M* signifies an energetic third body, from which energy is transferred during a molecular collision. Formaldehyde (HCHO, or H
2CO) is an early intermediate (reaction 7). Oxidation of formaldehyde gives the formyl radical (HCO; reactions 8–10), which then give carbon monoxide (CO) (reactions 11, 12 & 13). Any resulting H2 oxidizes to H2O or other intermediates (reaction 14, 15). Finally, the CO oxidizes, forming CO2 (reaction 16). In the final stages (reactions 17–19), energy is transferred back to other third bodies. The overall reaction rate is a function of the concentration of the various entities during the combustion process. The higher the temperature, the greater the concentration of radical species, and the more rapid the combustion process.[19]

text: Reactions with halogens[edit]

text: Given appropriate conditions, methane reacts with halogens as follows:

text: where X is a halogen: fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). This mechanism for this process is called free radical halogenation. It is initiated with UV light or some other radical initiator. A chlorine atom is generated from elemental chlorine, which abstracts a hydrogen atom from methane, resulting in the formation of hydrogen chloride. The resulting methyl radical, CH3•, can combine with another chlorine molecule to give methyl chloride (CH3Cl) and a chlorine atom. This chlorine atom can then react with another methane (or methyl chloride) molecule, repeating the chlorination cycle.[20] Similar reactions can produce dichloromethane (CH2Cl2), chloroform (CHCl3), and, ultimately, carbon tetrachloride (CCl4), depending upon reaction conditions and the chlorine to methane ratio.

text: Uses[edit]

text: Methane is used in industrial chemical processes and may be transported as a refrigerated liquid (liquefied natural gas, or LNG). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of the cold gas, the gas at ambient temperature is lighter than air. Gas pipelines distribute large amounts of natural gas, of which methane is the principal component.

text: Fuel[edit]

text: Methane is used as a fuel for ovens, homes, water heaters, kilns, automobiles,[21][22] turbines, and other things. It combusts with oxygen to create heat, as demonstrated by a British inventor in a 1974 film of the National Film Board of Canada.[23]

text: Natural gas[edit]

text: Methane is important for electricity generation by burning it as a fuel in a gas turbine or steam generator. Compared to other hydrocarbon fuels, methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion is lower than any other hydrocarbon but the ratio of the heat of combustion (891 kJ/mol) to the molecular mass (16.0 g/mol, of which 12.0 g/mol is carbon) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit (55.7 kJ/g) than other complex hydrocarbons. In many cities, methane is piped into homes for domestic heating and cooking. In this context it is usually known as natural gas, which is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot.

text: Methane in the form of compressed natural gas is used as a vehicle fuel and is claimed to be more environmentally friendly than other fossil fuels such as gasoline/petrol and diesel.[22] Research into adsorption methods of methane storage for use as an automotive fuel has been conducted.[24]

text: Liquefied natural gas[edit]

text: Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4) that has been converted to liquid form for ease of storage or transport.

text: Liquefied natural gas takes up about 1/600th the volume of natural gas in the gaseous state. It is odorless, colorless, non-toxic and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing, and asphyxia.

text: The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure (maximum transport pressure set at around 25 kPa or 3.6 psi) by cooling it to approximately −162 °C (−260 °F).[citation needed]

text: LNG achieves a higher reduction in volume than compressed natural gas (CNG) so that the energy density of LNG is 2.4 times greater than that of CNG or 60% that of diesel fuel.[25] This makes LNG cost efficient to transport over long distances where pipelines do not exist. Specially designed cryogenic sea vessels (LNG carriers) or cryogenic road tankers are used for its transport.

text: LNG, when it is not highly refined for special uses, is principally used for transporting natural gas to markets, where it is regasified and distributed as pipeline natural gas. It is also beginning to be used in LNG-fueled road vehicles. For example, trucks in commercial operation have been achieving payback periods of approximately four years on the higher initial investment required in LNG equipment on the trucks and LNG infrastructure to support fueling.[26] However, it remains more common to design vehicles to use compressed natural gas. As of 2002[update], the relatively higher cost of LNG production and the need to store LNG in more expensive cryogenic tanks had slowed widespread commercial use.[27]

text: Liquid methane rocket fuel[edit]

text: In a highly refined form, liquid methane is used as a rocket fuel.[28]

text: Though methane has been investigated for decades, no production methane engines have yet been used on orbital spaceflights.[29] Methane is reported to offer the advantage over Kerosene of depositing less carbon on the internal parts of rocket motors, reducing the difficulty of re-use of boosters.

text: Since the 1990s, a number of Russian rockets using liquid methane have been proposed.[30][31] One 1990s Russian engine proposal was the RD-192, a methane/LOX variant of the RD-191.[31]

text: In 2005, US companies, ORBITEC (Orbital Technologies Corporation, now part of Sierra Nevada Corporation as of 2014) and XCOR Aerospace, developed a demonstration liquid oxygen/liquid methane rocket engine and a larger 7,500 pounds-force (33 kN)-thrust engine in 2007 for potential use as the CEV lunar return engine, before the CEV program was later cancelled.[32][33][34]

text: More recently the American private space company SpaceX announced in 2012 an initiative to develop liquid methane rocket engines,[35] including initially, the very large Raptor rocket engine.[36] Raptor is being designed to produce 4.4 meganewtons (1,000,000 lbf) of thrust with a vacuum specific impulse (Isp) of 363 seconds and a sea-level Isp of 321 seconds,[37] and began component-level testing in 2014.[38] In February 2014, the Raptor engine design was shown to be of the highly efficient and theoretically more reliable full-flow staged combustion cycle type, where both propellant streams—oxidizer and fuel—are completely in the gas phase before they enter the combustion chamber. Prior to 2014, only two full-flow rocket engines had ever progressed sufficiently to be tested on test stands, but neither engine completed development or flew on a flight vehicle.[37] In 2016, a development Raptor engine was tested.[39]

text: In October 2013, the China Aerospace Science and Technology Corporation, a state-owned contractor for the Chinese space program, announced that it had completed a first ignition test on a new LOX methane rocket engine. No engine size was provided.[40]

text: In September 2014, another American private space company—Blue Origin— publicly announced that they were into their third year of development work on a large methane rocket engine. The new engine, the Blue Engine 4, or BE-4, has been designed to produce 2,400 kilonewtons (550,000 lbf) of thrust. While initially planned to be used exclusively on a Blue Origin proprietary launch vehicle, it will now be used on a new United Launch Alliance (ULA) engine on a new launch vehicle that is a successor to the Atlas V. ULA indicated in 2014 that they will make the maiden flight of the new launch vehicle no earlier than 2019.[41]

text: One advantage of methane is that it is abundant in many parts of the solar system and it could potentially be harvested on the surface of another solar-system body (in particular, using methane production from local materials found on Mars[42] or Titan), providing fuel for a return journey.[28][43]

text: By 2013, NASA's Project Morpheus had developed a small restartable LOX methane rocket engine with 5,000 pounds-force (22 kN) thrust and a specific impulse of 321 seconds suitable for inspace applications including landers. Small LOX methane thrusters 5–15 pounds-force (22–67 N) were also developed suitable for use in a Reaction Control System (RCS).[44][45]

text: SpaceNews is reporting in early 2015 that the French space agency CNES is working with Germany and a few other governments and will propose a LOX/methane engine on a reusable launch vehicle by mid-2015,[needs update] with flight testing unlikely before approximately 2026.[46]

text: Chemical feedstock[edit]

text: Although there is great interest in converting methane into useful or more easily liquefied compounds, the only practical processes are relatively unselective. In the chemical industry, methane is converted to synthesis gas, a mixture of carbon monoxide and hydrogen, by steam reforming. This endergonic process (requiring energy) utilizes nickel catalysts and requires high temperatures, around 700–1100 °C:

text: Related chemistries are exploited in the Haber-Bosch Synthesis of ammonia from air, which is reduced with natural gas to a mixture of carbon dioxide, water, and ammonia.

text: Methane is also subjected to free-radical chlorination in the production of chloromethanes, although methanol is a more typical precursor.[47]

text: Other commercially viable processes that use methane as a chemical feedstock include, the catalytic oxidation of methane into methanol[48] based on the oxidative coupling of methane, and the direct reaction of methane with sulfur trioxide to produce methanesulfonic acid.[49][50]

text: Generation[edit]

text: Geological routes[edit]

text: There are two main routes for geological methane generation, organic (thermogenic), and inorganic (abiotic, meaning non-living). Thermally generated methane, is referred to as thermogenic, originating from deeper sedimentary strata. Thermogenic methane (CH4) formation occurs due to the break-up of organic matter, forced by elevated temperatures and pressures. This type of methane is considered to be the primary methane type in sedimentary basins, and from an economical perspective the most important source of natural gas. Thermogenic methane components are generally considered to be relic (from an earlier time). Generally, formation of thermogenic methane (at depth), can occur through organic matter break-up, or organic synthesis, both ways can involve microorganisms (methanogenesis) but may also occur inorganically. The involved anaerobic and aerobic processes can also consume methane, with and without microorganisms.The more important source of methane at depth (crystalline bedrock) is abiotic. Abiotic means that the methane formation took place involving inorganic compounds, without biological activity, magmatic or created at low temperatures and pressures through water-rock reactions.[51][52]

text: Biological routes[edit]

text: Naturally occurring methane is mainly produced by microbial methanogenesis.[citation needed] This multistep process is used by microorganisms as an energy source. The net reaction is

text: The final step in the process is catalyzed by the enzyme Coenzyme-B sulfoethylthiotransferase. Methanogenesis is a form of anaerobic respiration used by organisms that occupy landfill, ruminants (e.g., cattle), and the guts of termites.

text: It is uncertain whether plants are a source of methane emissions.[53][54][55]

text: Industrial routes[edit]

text: There are many technological methane production methods. Methane created from biomass in industrial plants via biological route is called biogas. A more synthetic method to produce methane is hydrogenating carbon dioxide through the Sabatier process. Methane is also a side product of the hydrogenation of carbon monoxide in the Fischer–Tropsch process, which is practiced on a large scale to produce longer-chain molecules than methane. Example of large-scale coal-to-methane gasification is the Great Plains Synfuels plant, started in 1984 in Beulah, North Dakota as a way to develop abundant local resources of low-grade lignite, a resource that is otherwise very hard to transport for its weight, ash content, low calorific value and propensity to spontaneous combustion during storage and transport.

text: Methane as natural gas has been so abundant that synthetic production of it has been limited to special cases and as of 2016 covers only minor fraction of the methane used.

text: Power to methane[edit]

text: This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2017) (Learn how and when to remove this template message)

text: Power to methane is a technology that uses electrical power to produce hydrogen from water by electrolysis and uses the Sabatier reaction to combine hydrogen with carbon dioxide to produce methane. As of 2016, this is mostly under development and not in large-scale use. Theoretically, the process could be used as a buffer for excess and off-peak power generated by highly fluctuating wind generators and solar arrays. The conversion efficiency of power to methane is 49–65%, and full power–methane–power cycle is 30–38%.

text: Laboratory synthesis[edit]

text: Methane can be produced by the destructive distillation of acetic acid in the presence of soda lime or similar. Acetic acid is decarboxylated in this process. Methane can be prepared from aluminium carbide by reaction with water or strong acids. It is also made by reducing a solution of methanol and concentrated hydrochloric acid with iron powder, giving water and ferrous chloride as byproducts.

text: On Mars[edit]

text: Methane has been proposed as a possible rocket propellant on future Mars missions due in part to the possibility of synthesizing it on the planet by in situ resource utilization.[56] An adaptation of the Sabatier methanation reaction may be used with a mixed catalyst bed and a reverse water-gas shift in a single reactor to produce methane from the raw materials available on Mars, utilizing water from the Martian subsoil and carbon dioxide in the Martian atmosphere.[42]

text: Methane could also be produced by a non-biological process called serpentinization[a] involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars.[57]

text: Occurrence[edit]

text: Methane was discovered and isolated by Alessandro Volta between 1776 and 1778 when studying marsh gas from Lake Maggiore. It is the major component of natural gas, about 87% by volume. The major source of methane is extraction from geological deposits known as natural gas fields, with coal seam gas extraction becoming a major source (see Coal bed methane extraction, a method for extracting methane from a coal deposit, while enhanced coal bed methane recovery is a method of recovering methane from non-mineable coal seams). It is associated with other hydrocarbon fuels, and sometimes accompanied by helium and nitrogen. Methane is produced at shallow levels (low pressure) by anaerobic decay of organic matter and reworked methane from deep under the Earth's surface. In general, the sediments that generate natural gas are buried deeper and at higher temperatures than those that contain oil.

text: Methane is generally transported in bulk by pipeline in its natural gas form, or LNG carriers in its liquefied form; few countries transport it by truck.

text: Alternative sources[edit]

text: Apart from gas fields, an alternative method of obtaining methane is via biogas generated by the fermentation of organic matter including manure, wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock, under anaerobic conditions. Rice fields also generate large amounts of methane during plant growth. Methane hydrates/clathrates (ice-like combinations of methane and water on the sea floor, found in vast quantities) are a potential future source of methane. Cattle belch methane accounts for 16% of the world's annual methane emissions to the atmosphere.[58] One study reported that the livestock sector in general (primarily cattle, chickens, and pigs) produces 37% of all human-induced methane.[59] Early research has found a number of medical treatments and dietary adjustments that help slightly limit the production of methane in ruminants.[60][61] A 2009 study found that at a conservative estimate, at least 51% of global greenhouse gas emissions were attributable to the life cycle and supply chain of livestock products, meaning all meat, dairy, and by-products, and their transportation.[62] More recently, a 2013 study estimated that livestock accounted for 44 percent of human-induced methane and 14.5 percent of human-induced greenhouse gas emissions.[63] Many efforts are underway to reduce livestock methane production and trap the gas to use as energy.[64]

text: Paleoclimatology research published in Current Biology suggests that flatulence from dinosaurs may have warmed the Earth.[65]

text: Atmospheric methane[edit]

text: Methane is created near the Earth's surface, primarily by microorganisms by the process of methanogenesis. It is carried into the stratosphere by rising air in the tropics. Uncontrolled build-up of methane in the atmosphere is naturally checked – although human influence can upset this natural regulation – by methane's reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor. It has a net lifetime of about 10 years,[66] and is primarily removed by conversion to carbon dioxide and water.

text: In addition, there is a large (but unknown) amount of methane in methane clathrates in the ocean floors as well as the Earth's crust.

text: In 2010, methane levels in the Arctic were measured at 1850 nmol/mol, a level over twice as high as at any time in the 400,000 years prior to the industrial revolution. Historically, methane concentrations in the world's atmosphere have ranged between 300 and 400 nmol/mol during glacial periods commonly known as ice ages, and between 600 and 700 nmol/mol during the warm interglacial periods. Recent research suggests that the Earth's oceans are a potentially important new source of Arctic methane.[67]

text: Methane is an important greenhouse gas with a global warming potential of 34 compared to CO2 over a 100-year period, and 72 over a 20-year period.[68][69][70]

text: The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases (these gases don't include water vapor which is by far the largest component of the greenhouse effect).[6]

text: Clathrates[edit]

text: Methane is essentially insoluble in water, but it can be trapped in ice forming a similar solid. Significant deposits of methane clathrate have been found under sediments on the ocean floors of Earth at large depths.

text: Estimates consider up to 15,000 gigatonnes of carbon may be stored in the form of clathrates (hydrates) in the ocean floor, not accounting for abiotic methane, a relatively newly discovered source of methane, formed below the ocean floor, in the earth crust.[71] It has been suggested, that today's methane emission regime from the ocean floor, is potentially similar to that during the PETM.[72]

text: Arctic methane release from permafrost and methane clathrates is an expected consequence and further cause of global warming.[73][74][75]

text: Anaerobic oxidation of methane[edit]

text: There is a group of bacteria that drive methane oxidation with nitrite as the oxidant, the anaerobic oxidation of methane.[76]

text: Safety[edit]

text: Methane is nontoxic, yet it is extremely flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogen, and some halogen-containing compounds. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia may result if the oxygen concentration is reduced to below about 16% by displacement, as most people can tolerate a reduction from 21% to 16% without ill effects. The concentration of methane at which asphyxiation risk becomes significant is much higher than the 5–15% concentration in a flammable or explosive mixture. Methane off-gas can penetrate the interiors of buildings near landfills and expose occupants to significant levels of methane. Some buildings have specially engineered recovery systems below their basements to actively capture this gas and vent it away from the building.

text: Methane gas explosions are responsible for many deadly mining disasters.[77] A methane gas explosion was the cause of the Upper Big Branch coal mine disaster in West Virginia on April 5, 2010, killing 29.[78]

text: Extraterrestrial methane[edit]

text: Methane has been detected or is believed to exist on all planets of the solar system and most of the larger moons. With the possible exception of Mars, it is believed to have come from abiotic processes.

text:
Mercury – the tenuous atmosphere contains trace amounts of methane.[79]
Venus – the atmosphere contains a large amount of methane from 60 km (37 mi) to the surface according to data collected by the Pioneer Venus Large Probe Neutral Mass Spectrometer[80]
Moon – traces are outgassed from the surface[81]

text:
Mars – the Martian atmosphere contains 10 nmol/mol methane.[82] The source of methane on Mars has not been determined. Recent research suggests that methane may come from volcanoes, fault lines, or methanogens,[83] that it may be a byproduct of electrical discharges from dust devils and dust storms,[84] or that it may be the result of UV radiation.[85] In January 2009, NASA scientists announced that they had discovered that the planet often vents methane into the atmosphere in specific areas, leading some to speculate this may be a sign of biological activity below the surface.[86] Studies of a Weather Research and Forecasting model for Mars (MarsWRF) and related Mars general circulation model (MGCM) suggests that methane plume sources may be located within tens of kilometers, which is within the roving capabilities of future Mars rovers.[87] The Curiosity rover, which landed on Mars in August 2012, can distinguish between different isotopologues of methane;[88] but even if the mission determines that microscopic Martian life is the source of the methane, it probably resides far below the surface, beyond the rover's reach.[89] Curiosity's Sample Analysis at Mars (SAM) instrument is capable of tracking the presence of methane over time to determine whether it is constant, variable, seasonal, or random, providing further clues about its source.[90] The first measurements with the Tunable Laser Spectrometer (TLS) indicated that there is less than 5 ppb of methane at the landing site.[91][92][93][94]

Methane measurements in the atmosphere of Mars by the Curiosity rover.

The Mars Trace Gas Mission orbiter planned for launch in 2016 would further study Mars' methane[95][96] and its decomposition products such as formaldehyde and methanol. Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinization.[57] On July 19, 2013, NASA scientists reported finding "not much methane" (i.e., "an upper limit of 2.7 parts per billion of methane") around the Gale Crater where the Curiosity rover landed in August 2012.[97][98][99] On September 19, 2013, from further measurements by Curiosity, NASA scientists reported no detection of atmospheric methane with a value of 6999180000000000000♠0.18±0.67 ppbv corresponding to an upper limit of only 1.3 ppbv (95% confidence limit), and as a result, concluded that the probability of current methanogenic microbial activity on Mars is reduced.[100][101][102] On 16 December 2014, NASA reported the Curiosity rover detected a "tenfold spike", likely localized, in the amount of methane in the Martian atmosphere. Sample measurements taken "a dozen times over 20 months" showed increases in late 2013 and early 2014, averaging "7 parts of methane per billion in the atmosphere." Before and after that, readings averaged around one-tenth that level.[103][104]
Saturn – the atmosphere contains 4500 ± 2000 ppm methane[105]

Enceladus – the atmosphere contains 1.7% methane[106]
Iapetus[citation needed]
Titan – the atmosphere contains 1.6% methane and thousands of methane lakes have been detected on the surface.[107] In the upper atmosphere, methane is converted into more complex molecules including acetylene, a process that also produces molecular hydrogen. There is evidence that acetylene and hydrogen are recycled into methane near the surface. This suggests the presence either of an exotic catalyst, possibly an unknown form of methanogenic life.[108] Methane showers, probably prompted by changing seasons, have also been observed.[109] On October 24, 2014, methane was found in polar clouds on Titan.[110][111]

text:
Uranus – the atmosphere contains 2.3% methane[112]

Ariel – methane is believed to be a constituent of Ariel's surface ice
Miranda[citation needed]
Oberon – about 20% of Oberon's surface ice is composed of methane-related carbon/nitrogen compounds
Titania – about 20% of Titania's surface ice is composed of methane-related organic compounds[citation needed]
Umbriel – methane is a constituent of Umbriel's surface ice

Neptune – the atmosphere contains 1.5 ± 0.5% methane[113]

Triton – Triton has a tenuous nitrogen atmosphere with small amounts of methane near the surface.[114][115]

Pluto – spectroscopic analysis of Pluto's surface reveals it to contain traces of methane[116][117]

Charon – methane is believed present on Charon, but it is not completely confirmed[118]

Eris – infrared light from the object revealed the presence of methane ice[119]
Halley's Comet
Comet Hyakutake – terrestrial observations found ethane and methane in the comet[120]
Extrasolar planets – methane was detected on extrasolar planet HD 189733b; this is the first detection of an organic compound on a planet outside the solar system. Its origin is unknown, since the planet's high temperature (700 °C) would normally favor the formation of carbon monoxide instead.[121] Research indicates that meteoroids slamming against exoplanet atmospheres could add hydrocarbon gases such as methane, making the exoplanets look as though they are inhabited by life, even if they are not.[122]
Interstellar clouds[123]
The atmospheres of M-type stars.[124]


document_title: PowerShell

question_text: which version of powershell comes with windows 10

question_tokens: which version of powershell comes with windows 10

root

text: PowerShell

text: Background[edit]

text: Every version of Microsoft Windows for personal computers has included a command line interpreter (CLI) for managing the operating system. Its predecessor, MS-DOS, relied exclusively on a CLI. These are COMMAND.COM in MS-DOS and Windows 9x, and cmd.exe in the Windows NT family of operating systems. Both support a few basic internal commands. For other purposes, a separate console application must be written. They also include a basic scripting language (batch files), which can be used to automate various tasks. However, they cannot be used to automate all facets of graphical user interface (GUI) functionality, in part because command-line equivalents of operations are limited, and the scripting language is elementary. In Windows Server 2003, the situation was improved, but scripting support was still unsatisfactory.[10]

tag: p

text: Microsoft attempted to address some of these shortcomings by introducing the Windows Script Host in 1998 with Windows 98, and its command-line based host: cscript.exe. It integrates with the Active Script engine and allows scripts to be written in compatible languages, such as JScript and VBScript, leveraging the APIs exposed by applications via COM. However, it has its own deficiencies: its documentation is not very accessible, and it quickly gained a reputation as a system vulnerability vector after several high-profile computer viruses exploited weaknesses in its security provisions. Different versions of Windows provided various special-purpose command line interpreters (such as netsh and WMIC) with their own command sets but they were not interoperable.

text: In an interview published 2017 September 13, Jeffrey Snover explained the motivation for the project:[11]

text: I'd been driving a bunch of managing changes, and then I originally took the UNIX tools and made them available on Windows, and then it just didn't work. Right? Because there's a core architectural difference between Windows and Linux. On Linux, everything's an ASCII text file, so anything that can manipulate that is a managing tool.  AWK, grep, sed? Happy days!

text: I brought those tools available on Windows, and then they didn't help manage Windows because in Windows, everything's an API that returns structured data. So, that didn't help. [...] I came up with this idea of PowerShell, and I said, "Hey, we can do this better."

text: By 2002 Microsoft had started to develop a new approach to command line management, including a CLI called Monad (also known as Microsoft Shell or MSH). The ideas behind it were published in August 2002 in a white paper titled Monad Manifesto.[12]  Monad was to be a new extensible CLI with a fresh design that would be capable of automating a full range of core administrative tasks. Microsoft first showed off Monad at the Professional Development Conference in Los Angeles in October 2003. A private beta program began a few months later which eventually led to a public beta program.

text: Microsoft published the first Monad public beta release on June 17, 2005, Beta 2 on September 11, 2005, and Beta 3 on January 10, 2006. Not much later, on April 25, 2006 Microsoft formally announced that Monad had been renamed Windows PowerShell, positioning it as a significant part of their management technology offerings.[13]  Release Candidate 1 of PowerShell was released at the same time. A significant aspect of both the name change and the RC was that this was now a component of Windows, and not an add-on product.

text: Release Candidate 2 of PowerShell version 1 was released on September 26, 2006 with final Release to the web (RTW) on November 14, 2006 and announced at TechEd Barcelona. PowerShell for earlier versions of Windows was released on January 30, 2007.[14]

text: PowerShell v2.0 development began before PowerShell v1.0 shipped. During the development, Microsoft shipped three community technology preview (CTP). Microsoft made these releases available to the public. The last CTP release of Windows PowerShell v2.0 was made available in December 2008.

text: PowerShell v2.0 was completed and released to manufacturing in August 2009, as an integral part of Windows 7 and Windows Server 2008 R2. Versions of PowerShell for Windows XP, Windows Server 2003, Windows Vista and Windows Server 2008 were released in October 2009 and are available for download for both 32-bit and 64-bit platforms.[15]

text: Windows 10 shipped a testing framework for PowerShell.[16]

text: On 18 August 2016, Microsoft announced[17] that they had made PowerShell open-source and cross-platform with support for Windows, macOS, CentOS and Ubuntu.[5] The source code was published on GitHub.[18] The move to open source created a second incarnation of PowerShell called "PowerShell Core", which runs on .NET Core. It is distinct from "Windows PowerShell", which runs on the full .NET Framework.[19] Starting with version 5.1, PowerShell Core is bundled with Windows Server 2016 Nano Server.[20][21]

text: Design[edit]

text: PowerShell's developers based the core grammar of the tool on that of POSIX 1003.2.[22]

text: Windows PowerShell can execute four kinds of named commands:[23]

text:
cmdlets (.NET Framework programs designed to interact with PowerShell)
PowerShell scripts (files suffixed by .ps1)
PowerShell functions
standalone executable programs

tag: ul

text: If a command is a standalone executable program, PowerShell launches it in a separate process; if it is a cmdlet, it executes in the PowerShell process. PowerShell provides an interactive command-line interface, wherein the commands can be entered and their output displayed. The user interface, based on the Win32 console, offers customizable tab completion. PowerShell enables the creation of aliases for cmdlets, which PowerShell textually translates into invocations of the original commands.  PowerShell supports both named and positional parameters for commands. In executing a cmdlet, the job of binding the argument value to the parameter is done by PowerShell itself, but for external executables, arguments are parsed by the external executable independently of PowerShell interpretation.[citation needed]

text: The PowerShell Extended Type System (ETS) is based on the .NET type system, but with extended semantics (for example, propertySets and third-party extensibility). For example, it enables the creation of different views of objects by exposing only a subset of the data fields, properties, and methods, as well as specifying custom formatting and sorting behavior. These views are mapped to the original object using XML-based configuration files.[24]

text: Cmdlets[edit]

text: Cmdlets are specialized commands in the PowerShell environment that implement specific functions. These are the native commands in the PowerShell stack. Cmdlets follow a Verb-Noun naming pattern, such as Get-ChildItem, helping to make them self-descriptive.[25] Cmdlets output their results as objects and can also receive objects as input, making them suitable for use as recipients in a pipeline. If a cmdlet outputs multiple objects, each object in the collection is passed down through the entire pipeline before the next object is processed.[25]

text: Cmdlets are specialized .NET classes, which the PowerShell runtime instantiates and invokes at run-time. Cmdlets derive either from Cmdlet or from PSCmdlet, the latter being used when the cmdlet needs to interact with the PowerShell runtime.[25] These base classes specify certain methods – BeginProcessing(), ProcessRecord() and EndProcessing() – which the cmdlet's implementation overrides to provide the functionality. Whenever a cmdlet runs, PowerShell invokes these methods in sequence, with ProcessRecord() being called if it receives pipeline input.[26] If a collection of objects is piped, the method is invoked for each object in the collection. The class implementing the Cmdlet must have one .NET attribute – CmdletAttribute – which specifies the verb and the noun that make up the name of the cmdlet. Common verbs are provided as an enum.[27][28]

text: If a cmdlet receives either pipeline input or command-line parameter input, there must be a corresponding property in the class, with a mutator implementation. PowerShell invokes the mutator with the parameter value or pipeline input, which is saved by the mutator implementation in class variables. These values are then referred to by the methods which implement the functionality. Properties that map to command-line parameters are marked by ParameterAttribute[29] and are set before the call to BeginProcessing(). Those which map to pipeline input are also flanked by ParameterAttribute, but with the ValueFromPipeline attribute parameter set.[30]

text: The implementation of these cmdlet classes can refer to any .NET API and may be in any .NET language. In addition, PowerShell makes certain APIs available, such as WriteObject(), which is used to access PowerShell-specific functionality, such as writing resultant objects to the pipeline. Cmdlets can use .NET data access APIs directly or use the PowerShell infrastructure of PowerShell Providers, which make data stores addressable using unique paths. Data stores are exposed using drive letters, and hierarchies within them, addressed as directories. Windows PowerShell ships with providers for the file system, registry, the certificate store, as well as the namespaces for command aliases, variables, and functions.[31] Windows PowerShell also includes various cmdlets for managing various Windows systems, including the file system, or using Windows Management Instrumentation to control Windows components. Other applications can register cmdlets with PowerShell, thus allowing it to manage them, and, if they enclose any datastore (such as databases), they can add specific providers as well.[citation needed]

text: PowerShell V2 added a more portable version of Cmdlets called Modules.  The PowerShell V2 release notes state:

text: "Modules allow script developers and administrators to partition and organize their Windows PowerShell code in self-contained, reusable units. Code from a module executes in its own self-contained context and does not affect the state outside of the module. Modules also enable you to define a restricted runspace environment by using a script."[citation needed]

text: Pipeline[edit]

text: PowerShell implements the concept of a pipeline, which enables piping the output of one cmdlet to another cmdlet as input. For example, the output of the Get-Process cmdlet could be piped to the Where-Object to filter any process that has less than 1 MB of paged memory, and then to the Sort-Object cmdlet (e.g., to sort the objects by handle count), and then finally to the Select-Object cmdlet to select just the first 10 (i.e., the 10 processes based on handle count).[citation needed]

text: As with Unix pipelines, PowerShell pipelines can construct complex commands, using the | operator to connect stages. However, the PowerShell pipeline differs from Unix pipelines in that stages execute within the PowerShell runtime rather than as a set of processes coordinated by the operating system, and structured .NET objects, rather than byte streams, are passed from one stage to the next. Using objects and executing stages within the PowerShell runtime eliminates the need to serialize data structures, or to extract them by explicitly parsing text output.[32] An object can also encapsulate certain functions that work on the contained data, which become available to the recipient command for use.[33][34] For the last cmdlet in a pipeline, PowerShell automatically pipes its output object to the Out-Default cmdlet, which transforms the objects into a stream of format objects and then renders those to the screen.[35][36]

text: Because all PowerShell objects are .NET objects, they share a .ToString() method, which retrieves the text representation of the data in an object. In addition, PowerShell allows formatting definitions to be specified, so the text representation of objects can be customized by choosing which data elements to display, and in what manner. However, in order to maintain backwards compatibility, if an external executable is used in a pipeline, it receives a text stream representing the object, instead of directly integrating with the PowerShell type system.[37][38][39]

text: Scripting[edit]

text: Windows PowerShell includes a dynamically typed scripting language which can implement complex operations using cmdlets imperatively. The scripting language supports variables, functions, branching (if-then-else), loops (while, do, for, and foreach), structured error/exception handling and closures/lambda expressions,[40] as well as integration with .NET. Variables in PowerShell scripts are prefixed with $.  Variables can be assigned any value, including the output of cmdlets. Strings can be enclosed either in single quotes or in double quotes: when using double quotes, variables will be expanded even if they are inside the quotation marks. Enclosing the path to a file in braces preceded by a dollar sign (as in ${C:\foo.txt}) creates a reference to the contents of the file. If it is used as an L-value, anything assigned to it will be written to the file. When used as an R-value, the contents of the file will be read. If an object is assigned, it is serialized before being stored.[citation needed]

text: Object members can be accessed using . notation, as in C# syntax. PowerShell provides special variables, such as $args, which is an array of all the command line arguments passed to a function from the command line, and $_, which refers to the current object in the pipeline.[41] PowerShell also provides arrays and associative arrays. The PowerShell scripting language also evaluates arithmetic expressions entered on the command line immediately, and it parses common abbreviations, such as GB, MB, and KB.[42][43]

text: Using the function keyword, PowerShell provides for the creation of functions, the following general form:[44]

text: The defined function is invoked in either of the following forms:[44]

text: PowerShell supports named parameters, positional parameters, switch parameters and dynamic parameters.[44]

text:
PowerShell allows any .NET methods to be called by providing their namespaces enclosed in brackets ([]), and then using a pair of colons (::) to indicate the static method.[45] For example,
[System.Console]::WriteLine("PowerShell").
Objects are created using the New-Object cmdlet. Calling methods of .NET objects is accomplished by using the regular . notation.[45]

text: PowerShell accepts strings, both raw and escaped. A string enclosed between single quotation marks is a raw string while a string enclosed between double quotation marks is an escaped string. PowerShell treats straight and curly quotes as equivalent.[46]

text: For error handling, PowerShell provides a .NET-based exception-handling mechanism. In case of errors, objects containing information about the error (Exception object) are thrown, which are caught using the try ... catch construct (although a trap construct is supported as well). PowerShell can be configured to silently resume execution, without actually throwing the exception; this can be done either on a single command, a single session or perpetually.[47]

text: Scripts written using PowerShell can be made to persist across sessions in either a .ps1 file or a .psm1 file (the latter is used to implement a module). Later, either the entire script or individual functions in the script can be used. Scripts and functions operate analogously with cmdlets, in that they can be used as commands in pipelines, and parameters can be bound to them. Pipeline objects can be passed between functions, scripts, and cmdlets seamlessly. To prevent unintentional running of scripts, script execution is disabled by default and must be enabled explicitly.[48] Enabling of scripts can be performed either at system, user or session level. PowerShell scripts can be signed to verify their integrity, and are subject to Code Access Security.[49]

text: The PowerShell scripting language supports binary prefix notation similar to the scientific notation supported by many programming languages in the C-family.[50][better source needed]

text: Hosting[edit]

text: One can also use PowerShell embedded in a management application, which uses the PowerShell runtime to implement the management functionality. For this, PowerShell provides a managed hosting API. Via the APIs, the application can instantiate a runspace (one instantiation of the PowerShell runtime), which runs in the application's process and is exposed as a Runspace object.[6] The state of the runspace is encased in a SessionState object. When the runspace is created, the Windows PowerShell runtime initializes the instantiation, including initializing the providers and enumerating the cmdlets, and updates the SessionState object accordingly. The Runspace then must be opened for either synchronous processing or asynchronous processing. After that it can be used to execute commands.[citation needed]

text: To execute a command, a pipeline (represented by a Pipeline object) must be created and associated with the runspace. The pipeline object is then populated with the cmdlets that make up the pipeline. For sequential operations (as in a PowerShell script), a Pipeline object is created for each statement and nested inside another Pipeline object.[6] When a pipeline is created, Windows PowerShell invokes the pipeline processor, which resolves the cmdlets into their respective assemblies (the command processor) and adds a reference to them to the pipeline, and associates them with InputPipe, Outputpipe and ErrorOutputPipe objects, to represent the connection with the pipeline. The types are verified and parameters bound using reflection.[6] Once the pipeline is set up, the host calls the Invoke() method to run the commands, or its asynchronous equivalent – InvokeAsync(). If the pipeline has the Write-Host cmdlet at the end of the pipeline, it writes the result onto the console screen. If not, the results are handed over to the host, which might either apply further processing or display the output itself.[citation needed]

text: Microsoft Exchange Server 2007 uses the hosting APIs to provide its management GUI. Each operation exposed in the GUI is mapped to a sequence of PowerShell commands (or pipelines). The host creates the pipeline and executes them. In fact, the interactive PowerShell console itself is a PowerShell host, which interprets the scripts entered at command line and creates the necessary Pipeline objects and invokes them.[citation needed]

text: Desired State Configuration[edit]

text: DSC allows for declaratively specifying how a software environment should be configured.[51]

text: Upon running a configuration, DSC will ensure that the system gets the state described in the configuration. DSC configurations are idempotent.  The Local Configuration Manager (LCM) periodically polls the system using the control flow described by resources (imperative pieces of DSC) to make sure that the state of a configuration is maintained.

text: Versions[edit]

text: Initially using the code name "Monad", PowerShell was first shown publicly at the Professional Developers Conference in September 2003. All major releases are still supported, and each major release has featured backwards compatibility with preceding versions.

text: PowerShell 1.0[edit]

text: PowerShell 1.0 was released in November 2006 for Windows XP SP2, Windows Server 2003 SP1 and Windows Vista.[52] It is an optional component of Windows Server 2008.

text: PowerShell 2.0[edit]

text: PowerShell 2.0 is integrated with Windows 7 and Windows Server 2008 R2[53] and is released for Windows XP with Service Pack 3, Windows Server 2003 with Service Pack 2, and Windows Vista with Service Pack 1.[54][55]

text: PowerShell v2 includes changes to the scripting language and hosting API, in addition to including more than 240 new cmdlets.[56][57]

text: New features of PowerShell 2.0 include:[58][59][60]

text:
PowerShell remoting: Using WS-Management, PowerShell 2.0 allows scripts and cmdlets to be invoked on a remote machine or a large set of remote machines.
Background jobs: Also called a PSJob, it allows a command sequence (script) or pipeline to be invoked asynchronously.  Jobs can be run on the local machine or on multiple remote machines. An interactive cmdlet in a PSJob blocks the execution of the job until user input is provided.
Transactions: Enable cmdlet and developers can perform transactional operations. PowerShell 2.0 includes transaction cmdlets for starting, committing, and rolling back a PSTransaction as well as features to manage and direct the transaction to the participating cmdlet and provider operations. The PowerShell Registry provider supports transactions.
Advanced functions: These are cmdlets written using the PowerShell scripting language. Initially called "script cmdlets", this feature was later renamed "advanced functions".[61]
SteppablePipelines: This allows the user to control when the BeginProcessing(), ProcessRecord() and EndProcessing() functions of a cmdlet are called.
Modules: This allows script developers and administrators to organize and partition PowerShell scripts in self-contained, reusable units. Code from a module executes in its own self-contained context and does not affect the state outside the module. Modules can define a restricted runspace environment by using a script. They have a persistent state as well as public and private members.
Data language: A domain-specific subset of the PowerShell scripting language that allows data definitions to be decoupled from the scripts and allows localized string resources to be imported into the script at runtime (Script Internationalization).
Script debugging: It allows breakpoints to be set in a PowerShell script or function. Breakpoints can be set on lines, line & columns, commands and read or write access of variables.  It includes a set of cmdlets to control the breakpoints via script.
Eventing: This feature allows listening, forwarding, and acting on management and system events. Eventing allows PowerShell hosts to be notified about state changes to their managed entities. It also enables PowerShell scripts to subscribe to ObjectEvents, PSEvents, and WmiEvents and process them synchronously and asynchronously.
Windows PowerShell Integrated Scripting Environment (ISE): PowerShell 2.0 includes a GUI-based PowerShell host that provides integrated debugger, syntax highlighting, tab completion and up to 8 PowerShell Unicode-enabled consoles (Runspaces) in a tabbed UI, as well as the ability to run only the selected parts in a script.
Network file transfer: Native support for prioritized, throttled, and asynchronous transfer of files between machines using the Background Intelligent Transfer Service (BITS).[62]
New cmdlets: Including Out-GridView, which displays tabular data in the WPF GridView object, on systems that allow it, and if ISE is installed and enabled.
New operators: -Split, -Join, and Splatting (@) operators.
Exception handling with Try-Catch-Finally: Unlike other .NET languages, this allows multiple exception types for a single catch block.
Nestable Here-Strings: PowerShell Here-Strings have been improved and can now nest.[63]
Block comments: PowerShell 2.0 supports block comments using <# and #> as delimiters.[64]
New APIs: The new APIs range from handing more control over the PowerShell parser and runtime to the host, to creating and managing collection of Runspaces (RunspacePools) as well as the ability to create Restricted Runspaces which only allow a configured subset of PowerShell to be invoked. The new APIs also support participation in a Windows PowerShell managed transaction.

text: PowerShell 3.0[edit]

text: PowerShell 3.0 is integrated with Windows 8 and with Windows Server 2012. Microsoft has also made PowerShell 3.0 available for Windows 7 with Service Pack 1, for Windows Server 2008 with Service Pack 1, and for Windows Server 2008 R2 with Service Pack 1.[65][66]

text: PowerShell 3.0 is part of a larger package, Windows Management Framework 3.0 (WMF3), which also contains the WinRM service to support remoting.[66] Microsoft made several Community Technology Preview releases of WMF3. An early community technology preview 2 (CTP 2) version of Windows Management Framework 3.0 was released on 2 December 2011.[67] Windows Management Framework 3.0 was released for general availability in December 2012[68] and is included with Windows 8 and Windows Server 2012 by default.[69]

text: New features in PowerShell 3.0 include:[66][70]:33–34

text:
Scheduled jobs: Jobs can be scheduled to run on a preset time and date.
Session connectivity: Sessions can be disconnected and reconnected. Remote sessions have become more tolerant of temporary network failures.
Improved code writing: Code completion (IntelliSense) and snippets are added. PowerShell ISE allows users to use dialog boxes to fill in parameters for PowerShell cmdlets.
Delegation support: Administrative tasks can be delegated to users who do not have permissions for that type of task, without granting them perpetual additional permissions.
Help update: Help documentations can be updated via Update-Help command.
Automatic module detection: Modules are loaded implicitly whenever a command from that module is invoked. Code completion works for unloaded modules as well.
New commands: Dozens of new modules were added, including functionality to manage disks get-WmiObject win32_logicaldisk, volumes, firewalls, network connections and printer management, previously performed via WMI.[further explanation needed]

text: PowerShell 4.0[edit]

text: PowerShell 4.0 is integrated with Windows 8.1 and with Windows Server 2012 R2. Microsoft has also made PowerShell 4.0 available for Windows 7 SP1, Windows Server 2008 R2 SP1 and Windows Server 2012.[71]

text: New features in PowerShell 4.0 include:

text:
Desired State Configuration:[72][73][74] Declarative language extensions and tools that enable the deployment and management of configuration data for systems using the DMTF management standards and WS-Management Protocol
New default execution policy: On Windows Servers, the default execution Policy is now RemoteSigned.
Save-Help: Help can now be saved for modules that are installed on remote computers.
Enhanced debugging: The debugger now supports debugging workflows, remote script execution and preserving debugging sessions across PowerShell session reconnections.
-PipelineVariable switch: A new ubiquitous parameter to expose the current pipeline object as a variable for programming purposes
Network diagnostics to manage physical and Hyper-V's virtualized network switches
Where and ForEach method syntax provides an alternate method of filtering and iterating over objects.

text: PowerShell 5.0[edit]

text: Windows Management Framework (WMF) 5.0 RTM which includes PowerShell 5.0 was re-released to web on February 24, 2016, following an initial release with a severe bug.[75] Key features include OneGet PowerShell cmdlets to support Chocolatey's repository-based package management[76] and extending support for switch management to layer 2 network switches.[77]

text: New features in PowerShell 5.0 include:

text:
PowerShell class definitions (properties, methods)
PowerShell .NET Enumerations
Debugging for PowerShell Runspaces in remote processes
Debugging for PowerShell Background Jobs
Desired State Configuration (DSC) Local Configuration Manager (LCM) version 2.0
DSC partial configurations
DSC Local Configuration Manager meta-configurations
Authoring of DSC resources using PowerShell classes

text: PowerShell 5.1[edit]

text: It was released along with the Windows 10 Anniversary Update[78] on August 2, 2016, and in Windows Server 2016.[79] PackageManagement now supports proxies, PSReadLine now has ViMode support, and two new cmdlets were added: Get-TimeZone and Set-TimeZone. The LocalAccounts module allows for adding/removing local user accounts.[80] A preview for PowerShell 5.1 was released for Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2012 R2 on July 16, 2016,[81] and was released on January 19, 2017.[82]

text: PowerShell 5.1 is the first version to come in two editions of "Desktop" and "Core". The "Desktop" edition is the continuation of the traditional Windows PowerShell that runs on full .NET Framework stack. The "Core" edition runs on .NET Core and is bundled with Windows Server 2016 Nano Server. In exchange for smaller footprint, the latter lacks some features such as the cmdlets to manage clipboard or join a computer to a domain, WMI version 1 cmdlets, Event Log cmdlets and profiles.[21]

text: PowerShell Core 6.0[edit]

text: PowerShell Core 6.0 was first announced on 18 August 2016, when Microsoft unveiled PowerShell Core and its decision to make the product cross-platform, independent of Windows, free and open source.[5] It achieved general availability on 10 January 2018 for Windows, macOS and Linux. [83] It has its own support lifecycle and adheres to the Microsoft lifecycle policy that is introduced with Windows 10: Only the latest version of PowerShell Core is supported. Microsoft expects to release one minor version for PowerShell Core 6.0 every six months.[84]

text: The most significant change in this version of PowerShell is the expansion to the other platforms. For Windows administrators, this version of PowerShell is devoid of any major new features. In an interview with the community on 11 January 2018, the PowerShell team was asked to list the top 10 most exciting things that would happen for a Windows IT professional who would migrate from Windows PowerShell 5.1 to PowerShell Core 6.0; in response, Angel Calvo of Microsoft could only name two: cross-platform and open-source.[85]

text: Comparison of cmdlets with similar commands[edit]

text: The following table contains a selection of the cmdlets that ship with PowerShell, noting similar commands in other well-known command-line interpreters. Many of these similar commands come out-of-the-box defined as aliases within PowerShell, making it easy for people familiar with other common shells to start working.

text:
Comparison of PowerShell cmdlets with internal and external commands of other command-line interpreters

PowerShell (Cmdlet)

PowerShell (Alias)

Windows Command Prompt

Unix shell

Description

Get-ChildItem

gci, dir, ls

dir

ls

Lists all files and folders in the current or given folder

Test-Connection[a]

N/A

ping

ping

Sends ICMP echo requests to the specified machine from the current machine, or instructs another machine to do so

Get-Content

gc, type, cat

type

cat

Gets the content of a file

Get-Command

gcm

help

type, which, compgen

Lists available commands

Get-Help

help, man

help

apropos, man

Prints a command's documentation on the console

Clear-Host

cls, clear

cls

clear

Clears the screen[b]

Copy-Item

cpi, copy, cp

copy, xcopy, robocopy

cp

Copies files and folders to another location

Move-Item

mi, move, mv

move

mv

Moves files and folders to a new location

Remove-Item

ri, del, erase, rmdir, rd, rm

del, erase, rmdir, rd

rm, rmdir

Deletes files or folders

Rename-Item

rni, ren, mv

ren, rename

mv

Renames a single file, folder, hard link or symbolic link

Get-Location

gl, cd, pwd

cd

pwd

Displays the working path (current folder)

Pop-Location

popd

popd

popd

Changes the working path to the location most recently pushed onto the stack

Push-Location

pushd

pushd

pushd

Stores the working path onto the stack

Set-Location

sl, cd, chdir

cd, chdir

cd

Changes the working path

Tee-Object

tee

N/A

tee

Pipes input to a file or variable, passing the input along the pipeline

Write-Output

echo, write

echo

echo

Prints strings or other objects to the standard output

Get-Process

gps, ps

tlist,[c] tasklist[d]

ps

Lists all running processes

Stop-Process

spps, kill

kill,[c] taskkill[d]

kill[e]

Stops a running process

Select-String

sls

findstr

find, grep

Prints lines matching a pattern

Set-Variable

sv, set

set

env, export, set, setenv

Creates or alters the contents of an environment variable

Invoke-WebRequest

iwr, curl, wget[f]

N/A

wget, curl

Gets contents from a web page on the Internet

tag: table

text: Notes

text:
Jump up ^ While the external ping command remains available to PowerShell, Test-Connection's output is a structured object that can be programmatically inspected.[86]

Jump up ^ Clear-Host is implemented as a predefined PowerShell function.

^ Jump up to: a b Available in Windows NT4, Windows 98 Resource Kit, Windows 2000 Support Tools

^ Jump up to: a b Available in Windows XP Professional Edition and later

Jump up ^ Also used in UNIX to send a process any signal, the "Terminate" signal is merely the default

Jump up ^ curl and wget are absent from PowerShell Core, so as to not interfere with invoking similarly named components of non-Windows OSes.

text: File extensions[edit]

text:
PS1 – Windows PowerShell shell script[87]
PSD1 – Windows PowerShell data file (for Version 2)[88]
PSM1 – Windows PowerShell module file (for Version 2)[89]
PS1XML – Windows PowerShell format and type definitions[39][90]
CLIXML – Windows PowerShell serialized data[91]
PSC1 – Windows PowerShell console file[92]
PSSC – Windows PowerShell Session Configuration file[93]

text: Application support[edit]

text: Snap-ins and hosts[edit]

text:
Application

Version

Cmdlets

Provider

Management GUI

Exchange Server

2007

402

Yes

Yes

Windows Server

2008

Yes

Yes

No

Microsoft SQL Server

2008

Yes

Yes

No

Microsoft SharePoint

2010

Yes

Yes

No

System Center Configuration Manager

2012 R2

400+

Yes

No

System Center Operations Manager

2007

74

Yes

No

System Center Virtual Machine Manager

2007

Yes

Yes

Yes

System Center Data Protection Manager

2007

Yes

No

No

Windows Compute Cluster Server

2007

Yes

Yes

No

Microsoft Transporter Suite for Lotus Domino[94]

08.02.0012

47

No

No

Microsoft PowerTools for Open XML[95]

1.0

33

No

No

IBM WebSphere MQ[96]

6.0.2.2

44

No

No

Quest Management Shell for Active Directory[97]

1.7

95

No

No

Special Operations Software Specops Command[98]

1.0

Yes

No

Yes

VMware vSphere PowerCLI[99]

6.5 R1

500+

Yes

Yes

Internet Information Services[100]

7.0

54

Yes

No

Windows 7 Troubleshooting Center[101]

6.1

Yes

No

Yes

Microsoft Deployment Toolkit[102]

2010

Yes

Yes

Yes

NetApp PowerShell Toolkit[103][104]

4.2

2000+

Yes

Yes

JAMS Scheduler – Job Access & Management System[105]

5.0

52

Yes

Yes

UIAutomation[106]

0.8

432

No

No

Dell Equallogic[107]

3.5

55

No

No

LOGINventory[108]

5.8

Yes

Yes

Yes

SePSX[109]

0.4.1

39

No

No

text: Alternative implementation[edit]

text: A project named Pash (the name is a pun on the well-known "bash" Unix shell[110]) has been an open source and cross-platform re-implementation of PowerShell via the Mono framework. Pash was created by Igor Moochnick, written in C# and was released under the GNU General Public License. Pash development stalled in 2008, but was restarted in 2012.[110][111]


document_title: Meek Cutoff

question_text: what was wrong with the water in meeks cutoff

text: Meek Cutoff

text: History[edit]

text: In 1845 there were rumors circulating among the emigrants on the Oregon Trail that the Walla Walla and Cayuse Indians might possibly attack the settlers in the Blue Mountains of Oregon or along the Columbia River. Reports of threats came in conjunction with the murder of two Frenchmen in the area.[1] Stephen Meek, the older brother of Joe Meek, was an experienced fur trapper and explorer who made his living as a wagon train guide. Meek was unemployed at the time but was considered to be someone who was familiar with eastern Oregon. When he offered the emigrants an alternate route to avoid the Blue Mountains many decided to follow him.[2] Some 200 wagons and 1,000 people turned off the primary Oregon Trail at Vale and followed Meek into the Oregon desert where no wagons had traveled before.

text: Blazing a new trail[edit]

text: Meek led the wagon train southwest through the Malheur Mountains. They followed the Malheur River for the first two days but were then forced into the hill country. As they progressed the road became stonier. It was so hard on the oxen that several died each day.[3]

text: Some of the emigrants were not doing well, especially those who were already sick when the train took the cutoff. Just west of Castle Rock and along the North Fork of the Malheur River, a young mother of two small children was losing the battle to stay alive. “Rowland Chambers’ wife Sarah, the Captain’s daughter, had contracted camp fever earlier in the journey and was now critical. Everything possible was done to ease her distress as she lay in the wagon hovering between life and death but alas, to no avail. Sarah breathed her last breath at this camp and was laid to rest beneath the sagebrush.”[4] The next day the grieving husband was left behind with a horse as the train continued to journey on. He went down to the river and found a native stone that he smoothed, then he carved this inscription: “Mrs. S Chambers, Sep 3rd 1845.” It remains one of the few Oregon Trail gravestones in existence.

text: The very next day the train experienced its most difficult ascent. In order to reach a ridge west of the North Fork of the Malheur River, the emigrants were forced to climb a steep, narrow ravine choked with boulders. One emigrant wrote about moving “ten thousand stones” in order to make a roadbed. Some of the wagons were damaged during the 1,000 foot climb, but they were soon repaired and the wagons continued over the hill and down to Cottonwood Creek.[5]

text: The train continued over mountains until it finally came down East Cow Creek into the Harney Basin, in a region known today as the Oregon High Desert. The expression on Meek's face "changed to one of complete bewilderment, as if he were seeing the country for the first time."[6] When trapping in this area 10 years prior, the alkaline lakes flooded a large portion of the valley. But now it was a drought year, the lakes were small and everything looked different. They continued south along the Silvies River and out into the lake-bed where they turned west. As they made their way to Silver Creek there were some in the forward company who insisted they continue west to find a pass over the Cascades. Meek wanted to follow Silver Creek to the north, but they refused to follow him.

text: On September 11, 1845 James Field wrote in his diary:

text: It was his intention to follow down Crooked river to the Deschutes and down it to the old road, but when he came to the marshy lake spoken of last Sunday, the company refused to follow him if he made the circuit necessary to get around it upon Crooked river again so he struck off in a westerly direction in order to get upon the main Deschutes River. He well knew that there was a scarcity of grass and water across here and so informed them, but it was nearer and they would have him go it, and now blame him for coming the route they obliged him to.[7]

text: The train continued to Wagontire Mountain, a name it later received when early settlers found a wagon tire there. Here the emigrants camped in and around what they called the “Lost Hollow.” There was water and grass but not an ample supply for the emigrants and all their livestock. As emigrants further back in the train continued to arrive, circumstances in the camp became desperate. Water quickly became scarce and many ran out of their staple supplies. In a weakened condition, more travelers became sick. Camp fever and other ailments began to overcome large numbers, especially the children and elders.[8]

text: On September 13, Field again wrote:

text: Started this morning in expectation of a long drive across the plain before us, but when about four miles from camp met Meek’s wife in company with a friend, returning with the news that they had found no water as yet and requesting all who were at the spring to remain there until he found a camp and returned or sent word back for them to come on. Nothing remained for us to do but drive back to the camp we had just left, where we found Teatherow’s company also, so if misery loves company here is enough of it, for this small camping spot is nearly eaten out by our own large stock of cattle, and to add to all this there are some in the company nearly out of provisions.[9]

text: For weeks the emigrants had been finding out how unfamiliar Meek was with the area, especially as the wagons followed a serpentine route into Harney Valley. However, there was always enough grass and water to get by. But now as the train became stalled at the Lost Hollow tensions reached a boiling point. Scouts were sent out in all directions looking for water and they searched for long distances but all came back empty handed.

text: In 1849, Betsy Bayley recalled this event in a letter written to her sister in Ohio:

text: We camped at a spring which we gave the name of “The Lost Hollow” because there was very little water there. We had men out in every direction in search of water. They traveled 40 or 50 miles in search of water but found none. You cannot imagine how we all felt. Go back, we could not and we knew not what was before us. Our provisions were failing us. There was sorrow and dismay depicted on every countenance. We were like mariners lost at sea and in this mountainous wilderness we had to remain for five days. At last we concluded to take a Northwesterly direction . . . . After we got in the right direction, people began to get sick.[10]

text: The search for water ended when Meek climbed Midnight Point and from there he could see Buck Creek 25 miles due north.[11] The emigrants immediately left for Buck Creek but from this point on they were no longer following Meek.[12]

text: During this period of the journey - while emigrants were driving their livestock throughout the night to water – the John Herren family reportedly found some gold nuggets, which led to the legend of the Lost Blue Bucket Mine. The name came from the story later circulated by some of the emigrants. The Herrens reported that if they had remained at their campsite they could have filled a blue bucket with gold nuggets. This place has never been found, but if it exists it is thought by some to be between Wagontire Mountain and the south fork of the Crooked River.[13]

text: The train splits[edit]

text: When the train reached the springs at the south fork one group turned west while the other continued north. The larger group followed Samuel Parker up to Steen’s Ridge where wagon ruts can still be seen today. Their goal was to follow the Crooked River. The smaller group with Solomon Tetherow continued west along the north side of Hampton Butte and then followed Bear Creek. Meek traveled with this smaller company. With the help of a Native American who guided the group to water for a blanket, they reached the Deschutes River where Cline Falls is today, and then followed the Deschutes north. This group suffered more for lack of supplies, so they sent a relief party ahead to The Dalles. The relief party thought it would be a two-day journey, but it took them ten days. When they arrived at The Dalles they were in a starving condition and so weak that some of the men needed help dismounting their horses.[14]

text: The train reunites[edit]

text: On September 26, 1845, both groups arrived on the same day at Sagebrush Springs near present-day Gateway, Oregon. They had all traveled a long distance without water, and the whole train stopped to rest on the 27th. On that day Samuel Parker entered in his diary:

text: "May codent get to water and water was taken to them, 32 in number. Heare we beried 6 persons."

text: Parker later added these remarks:

text: "Tuck what is called Meeks cutoff - a bad cutoff for all that tuck it."[15]

text: Meek continued on ahead of the company, and when he reached Sherars Falls on the Deschutes River he was warned that a father who lost two sons along the trail intended to kill him, so with the help of Native Americans a rope was sent across the swift river, and both Meek and his wife were guided through the water with ropes tied around them. They hurried to the Mission at The Dalles where they convinced Black Harris, a mountain man, to return to the falls with a crew and equipment to help the emigrants cross. In this way Meek made his escape, and the crew sent to help the pioneers arrived in time to help the over 1,000 people cross with their wagons. The wagons were taken completely apart to facilitate the dangerous crossing. Some of the emigrants crossed from the low banks, using their wagon box as a boat and guided by ropes over the swift current. Others used a rope and pulley system above the high walls of the narrows about two miles downstream. It took nearly two weeks to cross everyone in the wagon train. The starving and exhausted emigrants finally reached The Dalles beginning around the 2nd week of October, having suffered 23 known deaths and probably many more.

text: It is estimated that another 25 of the exhausted emigrants died after reaching The Dalles.[16] The deaths and other circumstances created resentment towards Meek and led to the often used phrase “Meek deserted them in the desert.”[17], despite his having stayed with his emigrants throughout most of the journey.[18]

text: The Meek Cutoff is one of sixteen historic trails recognized by the State of Oregon.[19] The blazing of the Meek Cutoff led to later wagon roads and the settlement of the eastern and central regions of Oregon.[20]