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71-506: Cyane Fossae is a trough in the Diacria quadrangle of Mars. It is centered at 31.3° north latitude and 121.2° west longitude. It is 913 kilometres (567 mi) long and was named after a classical albedo feature name. The term " fossae " is used to indicate large troughs when using geographical terminology related to Mars. Troughs, sometimes also called grabens , form when the crust is stretched until it breaks, which forms two breaks with

142-438: A 1 molar ideal gas gives a correction for the thermodynamic environment (pressure and volume) in which pV = RT, hence a correction of 1RT. Additional corrections for the vibrations , rotations and translation then need to be applied. From the equipartition theorem gaseous rotation and translation contribute 1.5RT each to the final state, therefore a +3RT correction. Crystalline vibrations and rotations contribute 3RT each to

213-574: A gas. This is similar to what happens to dry ice on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Patterned ground forms in a mantle layer, called latitude dependent mantle , that fell from the sky when the climate was different. The western flank of the Alba Mons volcano makes up the eastern and southeastern edge of the quadrangle. In terms of area, Alba Mons (formerly, Alba Patera)

284-476: A landscape become filled with lava or sediment that hardens into material that is more resistant to erosion than the material that surrounds it. Differential erosion then removes the less resistant surrounding material, leaving behind the younger resistant material, which may then appear as a ridge where previously there was a valley. Terms such as "inverted valley" or "inverted channel" are used to describe such features. Inverted relief has been observed on

355-561: A layer of younger material. At the resolution of the Mars Orbital Camera (MOC) on the Mars Global Surveyor spacecraft (around several m per pixel), much of the northern plains has a distinctly stippled, pitted texture that causes the ground to resemble the surface of a basketball or orange rind. This texture is likely caused by a mantle of ice and dust covering the landscape. The small hollows and pits formed as

426-549: A middle section moving down, leaving steep cliffs along the sides. Sometimes, a line of pits form as materials collapse into a void that forms from the stretching. This article about the planet Mars or its moons is a stub . You can help Misplaced Pages by expanding it . Diacria quadrangle The southern and northern borders of the Diacria quadrangle are approximately 3,065 km (1,905 mi) and 1,500 km (930 mi) wide, respectively. The north to south distance

497-406: A process necessary for the completion of the magnum opus . Here, the word sublimation was used to describe an exchange of "bodies" and "spirits" similar to laboratory phase transition between solids and gases. Valentine, in his Le char triomphal de l'antimoine (Triumphal Chariot of Antimony, published 1646) made a comparison to spagyrics in which a vegetable sublimation can be used to separate

568-410: A solid, turning it into a gas through an endothermic reaction without passing through the liquid phase. In sublimation printing, unique sublimation dyes are transferred to sheets of “transfer” paper via liquid gel ink through a piezoelectric print head. The ink is deposited on these high-release inkjet papers, which are used for the next step of the sublimation printing process. After the digital design

639-430: Is deposition (also called desublimation ), in which a substance passes directly from a gas to a solid phase, without passing through the liquid state. Technically, all solids may sublime, though most sublime at extremely low rates under usual conditions that are hardly detectable. At normal pressures , most chemical compounds and elements possess three different states at different temperatures . In these cases,

710-585: Is not sublimation but a chemical reaction. Similarly the combustion of candles, containing paraffin wax , to carbon dioxide and water vapor is not sublimation but a chemical reaction with oxygen. Sublimation is historically used as a generic term to describe a two-step phase transition ― a solid-to-gas transition (sublimation in a more precise definition) followed by a gas-to-solid transition ( deposition ). (See below ) The examples shown are substances that noticeably sublime under certain conditions. Solid carbon dioxide ( dry ice ) sublimes rapidly along

781-440: Is a digital printing technology using full color artwork that works with polyester and polymer-coated substrates. Also referred to as digital sublimation, the process is commonly used for decorating apparel, signs and banners, as well as novelty items such as cell phone covers, plaques, coffee mugs, and other items with sublimation-friendly surfaces. The process uses the science of sublimation, in which heat and pressure are applied to

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852-415: Is a technique used by chemists to purify compounds . A solid is typically placed in a sublimation apparatus and heated under vacuum . Under this reduced pressure , the solid volatilizes and condenses as a purified compound on a cooled surface ( cold finger ), leaving a non-volatile residue of impurities behind. Once heating ceases and the vacuum is removed, the purified compound may be collected from

923-454: Is about 2,050 km (1,270 mi) (slightly less than the length of Greenland). The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars' surface area. The Phoenix lander's landing site (68.22° N, 234.25° E) lies about 186 km (116 mi) north of the northeastern quarter of the Diacria quadrangle. The landscape viewed by the Phoenix lander

994-415: Is divided into two types: vaporization on the surface of the liquid is called evaporation , and vaporization at the boiling point with formation of bubbles in the interior of the liquid is called boiling . However there is no such distinction for the solid-to-gas transition, which is always called sublimation in both corresponding cases. For clarification, a distinction between the two corresponding cases

1065-488: Is located at the northwestern edge of the Tharsis volcanic plateau. Topographic, volcanic, and tectonic features associated with the large volcanoes Olympus Mons (south of map area) and Alba Mons (east of map area) characterize the southeastern and east central portions of the quadrangle. The northern and western areas of the quadrangle lie in the northern lowland plains of Mars and cover portions of Amazonis Planitia (in

1136-441: Is made of non-polar molecules that are held together only by van der Waals intermolecular forces. Naphthalene is a solid that sublimes gradually at standard temperature and pressure , at a high rate, with the critical sublimation point at around 80 °C (176 °F). At low temperature, its vapour pressure is high enough, 1   mmHg at 53   °C, to make the solid form of naphthalene evaporate into gas. On cool surfaces,

1207-454: Is much more achievable than evaporation from liquid state and it is difficult to obtain them as liquids. This is because the pressure of their triple point in its phase diagram (which corresponds to the lowest pressure at which the substance can exist as a liquid) is very high. Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the attractive forces of their neighbors and escape into

1278-462: Is needed. With reference to a phase diagram , the sublimation that occurs left of the solid-gas boundary, the triple point or the solid-liquid boundary (corresponding to evaporation in vaporization) may be called gradual sublimation ; and the substance sublimes gradually , regardless of rate. The sublimation that occurs at the solid-gas boundary (critical sublimation point) (corresponding to boiling in vaporization) may be called rapid sublimation , and

1349-405: Is partially covered by volcanic deposits from Alba Mons in the east, geologically young basaltic lava flows or sediments in the west and southeast, and the jumbled, furrowed terrain of Lycus Sulci in the south. Lycus Sulci (24.6° N, 219° E) is the name applied to the northwestern portion of a larger terrain feature that partially encircles Olympus Mons and extends up to 750 km from

1420-405: Is printed onto sublimation transfer sheets, it is placed on a heat press along with the substrate to be sublimated. In order to transfer the image from the paper to the substrate, it requires a heat press process that is a combination of time, temperature and pressure. The heat press applies this special combination, which can change depending on the substrate, to “transfer” the sublimation dyes at

1491-528: Is probably representative of a large portion of the terrain in the northern Diacria quadrangle. Diacria is the name of a telescopic albedo feature located at 48° N and 190° E on Mars. The feature was named by Greek astronomer E. M. Antoniadi in 1930 after Diacria , the highlands around Marathon in north-west Attica , Greece. The name was approved by the International Astronomical Union (IAU) in 1958. The Diacria quadrangle

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1562-479: Is still going. The pattern of the tracks have been shown to change every few months. The triangular depressions visible in Milankovič crater contain water ice in the straight wall that faces the pole, according to a new study. Eight sites were found with Milankovič crater being the only one in the northern hemisphere. This discovery is important because the ice lies under only a meter or two of cover. Research

1633-418: Is that from its filthy original. It may be cleansed, and its saltiness sulphurious May be diminished in it, which is infectious. The enthalpy of sublimation has commonly been predicted using the equipartition theorem . If the lattice energy is assumed to be approximately half the packing energy, then the following thermodynamic corrections can be applied to predict the enthalpy of sublimation. Assuming

1704-590: Is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is sublime , or less preferably, sublimate . Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for further details, see below ) is called critical sublimation point, or simply sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation

1775-417: Is the largest volcanic feature on Mars. The flank has a very low slope (l° or less) and is characterized by lava flows and an outwardly radiating array of ridges and channels. Some of the channels have a drainage pattern that resembles that formed by rain water on the slopes of terrestrial volcanoes. However, many other channels on the flanks of Alba Mons were clearly formed by flowing lava. The western flank of

1846-754: The Thermal Emission Spectrometer (TES) on the Mars Global Surveyor spacecraft has allowed planetary scientists to estimate the amount of dust cover for broad swaths of the planet. In general, the Diacria quadrangle is extremely dusty, particularly in Arcadia Planitia and the region around the flank of Alba Mons and the Olympus Mons aureole in the southeastern portion of the quadrangle. A few large patches of relatively low dust cover occur in Amazonis Planitia and in

1917-402: The organic electronics industry , where very high purities (often > 99.99%) are needed to satisfy the standards for consumer electronics and other applications. In ancient alchemy , a protoscience that contributed to the development of modern chemistry and medicine, alchemists developed a structure of basic laboratory techniques, theory, terminology, and experimental methods. Sublimation

1988-420: The 1970s show that large portions of Arcadia Planitia have an overall mottled (blotchy light and dark) appearance. At higher resolution, landforms commonly consist of lobate flow fronts; small channel segments; wrinkle ridges ; pedestal craters ; and low, isolated volcano-like hills with summit craters. MOLA images reveal numerous large, shallowly buried craters, suggesting that an old cratered surface lies under

2059-420: The atmosphere. The water returns to the ground at lower latitudes as deposits of frost or snow mixed with dust. The atmosphere of Mars contains a great deal of fine dust particles. Water vapor condenses on the particles, then they fall down to the ground due to the additional weight of the water coating. When ice at the top of the mantling layer goes back into the atmosphere, it leaves behind dust, which insulates

2130-505: The basis of their form, aspects, positions, and location amongst and apparent interaction with features thought to be rich in water ice, many researchers believed that the processes carving the gullies involve liquid water. However, this remains a topic of active research. The pictures below show examples of gullies in Diacria quadrangle. There is enormous evidence that water once flowed in river valleys on Mars. Images of curved channels have been seen in images from Mars spacecraft dating to

2201-417: The cooling surface. For even higher purification efficiencies, a temperature gradient is applied, which also allows for the separation of different fractions. Typical setups use an evacuated glass tube that is heated gradually in a controlled manner. The material flow is from the hot end, where the initial material is placed, to the cold end that is connected to a pump stand. By controlling temperatures along

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2272-635: The dust storm. Other global dust storms have also been observed, since that time. Research, published in January 2012 in Icarus, found that dark streaks were initiated by airblasts from meteorites traveling at supersonic speeds. The team of scientists was led by Kaylan Burleigh, an undergraduate at the University of Arizona. After counting some 65,000 dark streaks around the impact site of a group of five new craters, patterns emerged. The number of streaks

2343-629: The early 1970s with the Mariner 9 orbiter. Indeed, a study published in June 2017, calculated that the volume of water needed to carve all the channels on Mars was even larger than the proposed ocean that the planet may have had. Water was probably recycled many times from the ocean to rainfall around Mars. Inverted relief , inverted topography , or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most often occurs when low areas of

2414-399: The edges of the Olympus Mons shield. Westward from Lycus Sulci, across the flat plains of Amazonis Planitia, lies an elongated region of knobby terrain called Erebus Montes (Erebus Mountains). The region contains hundreds of clustered to isolated hillocks that stand 500 to 1,000 m above the surrounding plains. The presence of numerous partly filled "ghost" craters in the area indicates that

2485-464: The giant shield volcano's base. This feature, called the Olympus Mons aureole, consists of several large lobes and has a distinctive corrugated or grooved surface texture. East of Olympus Mons, the aureole is partially covered by lava flows, but where it is exposed it goes by different names ( Gigas Sulci , for example). The origin of the aureole remains debated, but it was likely formed by huge landslides or gravity-driven thrust sheets that sloughed off

2556-539: The growth of organisms . The streaks appear in areas covered with dust. Much of the Martian surface is covered with dust because at more or less regular intervals dust settles out of the atmosphere covering everything. We know a lot about this dust because the solar panels of Mars rovers get covered with dust. The power of the Rovers has been saved many times by the wind, in the form of dust devils that have cleared

2627-638: The hills represent the high-standing remnants of ancient highland crust that was inundated by lava flows and (possibly) alluvial sediments from Tharsis in the southeast and the Elysium volcanic province to the west. North and east of the Erebus Montes are low-lying plains that characterize a large part of the Diacria Quadrangle and of the Martian northern hemisphere in general. Medium resolution Mariner 9 and Viking spacecraft images from

2698-442: The ice changes directly from a solid to gaseous form. In the impact, the excess ice is broken up, resulting in an increase in surface area. Ice will sublimate much more if there is more surface area. After the ice disappears into the atmosphere, dry soil material will collapse and cause the crater diameter to become larger. Places on Mars that display expanded craters may indicate where future colonists can find water ice. Much of

2769-426: The ice evaporated (sublimed). The geologic history and origin of the northern plains are complex and still poorly understood. Many of the landforms resemble periglacial features seen on Earth, such as moraines , ice-wedged polygons , and pingos . Arcadia Planitia and Vastitas Borealis likely consist of a hodgepodge of old lava flows, ice-related features, and reworked sediments of diverse origin. Some theorize that

2840-520: The initial state, hence −6RT. Summing the RT corrections; −6RT + 3RT + RT = −2RT. This leads to the following approximate sublimation enthalpy. A similar approximation can be found for the entropy term if rigid bodies are assumed. Δ H sublimation = − U lattice energy − 2 R T {\displaystyle \Delta H_{\text{sublimation}}=-U_{\text{lattice energy}}-2RT} Dye-sub printing

2911-453: The length of the tube, the operator can control the zones of re-condensation, with very volatile compounds being pumped out of the system completely (or caught by a separate cold trap ), moderately volatile compounds re-condensing along the tube according to their different volatilities, and non-volatile compounds remaining in the hot end. Vacuum sublimation of this type is also the method of choice for purification of organic compounds for use in

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2982-404: The molecular level into the substrate. The most common dyes used for sublimation activate at 350 degrees Fahrenheit. However, a range of 380 to 420 degrees Fahrenheit is normally recommended for optimal color. The result of the sublimation process is a nearly permanent, high resolution, full color print. Because the dyes are infused into the substrate at the molecular level, rather than applied at

3053-686: The naphthalene vapours will solidify to form needle-like crystals. Iodine sublimes gradually and produces visible fumes on gentle heating at standard atmospheric temperature . It is possible to obtain liquid iodine at atmospheric pressure by controlling the temperature at just between the melting point and the boiling point of iodine. In forensic science , iodine vapor can reveal latent fingerprints on paper. At atmospheric pressure , arsenic sublimes gradually upon heating, and sublimes rapidly at 887 K (614 °C). Cadmium and zinc sublime much more than other common materials, so they are not suitable materials for use in vacuum . Sublimation

3124-420: The northern plains were once covered by oceans or large lakes. Large impacts often create swarms of small secondary craters from the debris that is blasted out as a consequence of the impact. Studies of a type of secondary craters, called expanded craters , have given us insights into places where abundant ice may be present in the ground. Expanded craters have lost their rims, this may be because any rim that

3195-552: The northwest corner of the quadrangle. Many areas on Mars, including the Diacria quadrangle, experience the passage of giant dust devils . When a dust devil goes by it blows away the coating of dust and exposes the underlying dark surface. Dust devils have been seen from the ground and high overhead from orbit. They have even blown the dust off of the solar panels of the two Rovers on Mars, thereby greatly extending their lives. The twin Rovers were designed to last for three months; instead they both lasted more than six years, and one

3266-485: The northwest, with the highest elevation about 3.5 km (2.2 mi) above datum (Mars "sea level") on the western flank of the Alba Mons volcano in the southeastern portion of the quadrangle. The lowest points in the quadrangle are about 4.5 km below datum (-4,500 m) in Vastitas Borealis in the northwest corner. The regional relief is thus about 8 km, but at a local scale, slopes are very shallow;

3337-416: The panels and boosted the power. So we know that dust falls from the atmosphere frequently. It is most generally accepted that the streaks represent avalanches of dust. Streaks appear in areas covered with dust. When a thin layer of dust is removed, the underlying surface appears dark. Much of the Martian surface is covered with dust. Dust storms are frequent, especially when the spring season begins in

3408-494: The portion of Amazonis Planitia in the south central part of the quadrangle contains some of the flattest terrain on the entire planet. Unlike some other places visited on Mars with landers ( Viking and Pathfinder ), nearly all the rocks near Phoenix are small. For about as far as the camera can see, the land is flat, but shaped into polygons between 2–3 meters in diameter and is bounded by troughs that are 20 to 50 cm (8 to 20 in) deep. These shapes are due to ice in

3479-662: The remaining ice. A study reported in the journal Science in September 2009, shows that some newly formed craters have excavated clean, water ice from just below the surface in five locations on Mars. After a short time, the ice disappears, subliming into the atmosphere. The ice is only a few meters deep. The ice was confirmed with the Compact Imaging Spectrometer ( CRISM ) on board the Mars Reconnaissance Orbiter (MRO). The ice

3550-442: The soil expanding and contracting due to major temperature changes. The microscope showed that the soil on top of the polygons is composed of flat particles (probably a type of clay) and rounded particles. Also, unlike other places visited on Mars, the site has no ripples or dunes. Ice is present a few inches below the surface in the middle of the polygons, and along its edges, the ice is at least 8 inches (20 cm) deep. Pictures of

3621-477: The solid-gas boundary (sublimation point) below the triple point (e.g., at the temperature of −78.5 °C, at atmospheric pressure ), whereas its melting into liquid CO 2 can occur along the solid-liquid boundary ( melting point ) at pressures and temperatures above the triple point (i.e., 5.1 atm, −56.6 °C). Snow and ice sublime gradually at temperatures below the solid-liquid boundary (melting point) (generally 0 °C), and at partial pressures below

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3692-558: The south), Arcadia Planitia (west central) and Vastitas Borealis (in the north). The large crater Milankovič (118.4 km in diameter) is located in the north central portion of the quadrangle at 54.7° N, 213.3° E. Elevation data from the Mars Orbital Laser Altimeter (MOLA) instrument on the Mars Global Surveyor spacecraft shows that the regional terrain slopes gently downward to

3763-416: The southeast corner of the quadrangle (37° N, 225° E) lies a southward sloping, semicircular block of ancient, heavily cratered, highland crust that is dissected by numerous, arcuate troughs ( Acheron Fossae ). The troughs are grabens, structures formed when the crust moves downward between two faults. Grabens form in areas where the crust has undergone extensional stress. The Acheron Fossae region

3834-486: The southern hemisphere. At that time, Mars is 40% closer to the Sun. The orbit of Mars is much more elliptical then the Earth's. That is the difference between the farthest point from the Sun and the closest point to the Sun is very great for Mars, but only slight for the Earth. Also, every few years, the entire planet is engulfed in a global dust storm. When NASA's Mariner 9 craft arrived there, nothing could be seen through

3905-455: The spirits in wine and beer. Ripley used language more indicative of the mystical implications of sublimation, indicating that the process has a double aspect in the spiritualization of the body and the corporalizing of the spirit. He writes: And Sublimations we make for three causes, The first cause is to make the body spiritual. The second is that the spirit may be corporeal, And become fixed with it and consubstantial. The third cause

3976-436: The substance sublimes rapidly . The words "gradual" and "rapid" have acquired special meanings in this context and no longer describe the rate of sublimation. The term sublimation refers specifically to a physical change of state and is not used to describe the transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid ammonium chloride into hydrogen chloride and ammonia

4047-518: The surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smooths the land. Because there are few craters on this mantle, the mantle is relatively young. Changes in Mars's orbit and tilt cause significant changes in the distribution of water ice from polar regions down to latitudes equivalent to Texas. During certain climate periods water vapor leaves polar ice and enters

4118-421: The surface under the lander appear to show that the landing rockets may have exposed a layer of ice. When the ice is exposed to the Martian atmosphere it slowly sublimates . Some dust devils were observed. Polygonal patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. Sublimation is the direct change of solid ice to

4189-426: The surfaces of other planets as well as on Earth. For example, well-documented inverted topographies have been discovered on Mars . Brain terrain is common in many places on Mars. It is formed when ice sublimates along cracks. The ridges of brain terrain may contain a core of ice. Shadow measurements from HiRISE indicate the ridges are 4–5 meters high. Sublimation (chemistry) Sublimation

4260-526: The transition from the solid to the gas state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. Thus, any solid can sublime if its vapour pressure is higher than the surrounding partial pressure of the same substance, and in some cases, sublimes at an appreciable rate (e.g. water ice just below 0 °C). For some substances, such as carbon and arsenic , sublimation from solid state

4331-563: The triple point pressure of 612 Pa (0.00604 atm), at a low rate. In freeze-drying , the material to be dehydrated is frozen and its water is allowed to sublime under reduced pressure or vacuum. The loss of snow from a snowfield during a cold spell is often caused by sunshine acting directly on the upper layers of the snow. Sublimation of ice is a factor to the erosive wear of glacier ice , also called ablation in glaciology . Naphthalene , an organic compound commonly found in pesticides such as mothballs , sublimes easily because it

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4402-403: The vapor phase. Since the process requires additional energy, sublimation is an endothermic change. The enthalpy of sublimation (also called heat of sublimation) can be calculated by adding the enthalpy of fusion and the enthalpy of vaporization . While the definition of sublimation is simple, there is often confusion as to what counts as a sublimation. Vaporization (from liquid to gas)

4473-463: The volcano also contains some NW-SE trending grabens ( Cyane Fossae ). An image from High Resolution Imaging Science Experiment ( HiRISE ) on the Mars Reconnaissance Orbiter (MRO) beautifully shows a line of rimless pit craters in Cyane Fossae. The pits may have formed by the collapse of surface materials into open fractures created as magma intruded the subsurface rock to form dikes . Near

4544-419: The walls of craters. Usually, each gully has a dendritic alcove at its head, a fan-shaped apron at its base, and a single thread of incised channel linking the two, giving the whole gully an hourglass shape. They are believed to be relatively young because they have few, if any craters. A subclass of gullies is also found cut into the faces of sand dunes which themselves considered to be quite young. On

4615-481: Was conducted with instruments on board the Mars Reconnaissance Orbiter (MRO). The following images are ones referred to in this study of subsurface ice sheets. Martian gullies are small, incised networks of narrow channels and their associated downslope sediment deposits, found on the planet of Mars . They are named for their resemblance to terrestrial gullies . First discovered on images from Mars Global Surveyor , they occur on steep slopes, especially on

4686-499: Was found in a total of five locations. One of the locations (Site 5) is in the Diacria quadrangle at about 46° N, 182° E (Arcadia Planitia). This discovery is significant because it shows the presence of subsurface ice at latitudes further south than expected and proves that future colonists on Mars will be able to obtain water from a wide variety of locations. The ice can be dug up, melted, and then taken apart to provide fresh oxygen and hydrogen for rocket fuel. Hydrogen

4757-430: Was greatest closer to the impact site. So, the impact somehow probably caused the streaks. Also, the distribution of the streaks formed a pattern with two wings extending from the impact site. The curved wings resembled scimitars, curved knives. This pattern suggests that an interaction of airblasts from the group of meteorites shook dust loose enough to start dust avalanches that formed the many dark streaks. At first it

4828-506: Was once present has collapsed into the crater during expansion or, lost its ice, if composed of ice. Excess ice (ice in addition to what is in the pores of the ground) is widespread throughout the Martian mid-latitudes, especially in Arcadia Planitia . In this region, are many expanded secondary craters that probably form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. With sublimation

4899-474: Was the powerful fuel used by the Space Shuttle main engines. Many places on Mars show dark streaks on steep slopes , such as crater walls. It seems that the youngest streaks are dark and they become lighter with age. Often they begin as a small narrow spot then widen and extend downhill for hundreds of meters. Several ideas have been advanced to explain the streaks. Some involve water , or even

4970-500: Was thought that the shaking of the ground from the impact caused the dust avalanches, but if that was the case the dark streaks would have been arranged symmetrically around the impacts, rather than being concentrated into curved shapes. Dark streaks can be seen in some of the images below. Large portions of the martian surface are blanketed with bright reddish-ochre dust. The dust particles are typically less than 40 micrometres in size and are composed of iron oxide minerals. Data from

5041-459: Was used to refer to the process in which a substance is heated to a vapor, then immediately collects as sediment on the upper portion and neck of the heating medium (typically a retort or alembic ), but can also be used to describe other similar non-laboratory transitions. It was mentioned by alchemical authors such as Basil Valentine and George Ripley , and in the Rosarium philosophorum , as

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