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Цитатаphys.org написал:OCTOBER 24, 2019Martian landslides not conclusive evidence of iceby University College LondonLandslide deposits, Coprates Labes, located in Valles Marineris. Credit: Giulia Magnarini / NASADetailed three-dimensional images of an extensive landslide on Mars, which spans an area more than 55 kilometres wide, have been analysed to understand how the unusually large and long ridges and furrows formed about 400 million years ago.The findings, published today in Nature Communications, show for the first time that the unique structures on Martian landslides fr om mountains several kilometres high could have formed at high speeds of up to 360 kilometres per hour due to underlying layers of unstable, fragmented rocks.This challenges the idea that underlying layers of slippery ice can only explain such long vast ridges, which are found on landslides throughout the Solar System. Скрытый текст: First author, Ph.D. student Giulia Magnarini (UCL Earth Sciences), said: "Landslides on Earth, particularly those on top of glaciers, have been studied by scientists as a proxy for those on Mars because they show similarly shaped ridges and furrows, inferring that Martian landslides also depended on an icy substrate."However, we've shown that ice is not a prerequisite for such geological structures on Mars, which can form on rough, rocky surfaces. This helps us better understand the shaping of Martian landscapes and has implications for how landslides form on other planetary bodies including Earth and the Moon."The team, from UCL, the Natural History Museum (London), Ben Gurion University of Negev (Israel) and University of Wisconsin Madison (USA), used images taken by NASA's Mars Reconnaissance Orbiter to analyse some of the best-defined landslides remotely.Cross-sections of the Martian surface in the Coprates Chasma in the Valles Marineris were analysed to investigate the relationship between the height of the ridges and width of the furrows compared to the thickness of the landslide deposit.The Martian landscape annotated with London and global landmarks for scale. Credit: Giulia Magnarini / NASAThe structures were found to display the same ratios as those commonly seen in fluid dynamics experiments using sand, suggesting an unstable and dry rocky base layer is as feasible as an icy one in creating the vast formations.Where landslide deposits are thickest, ridges form 60 metres high and furrows are as wide as eight Olympic-sized swimming pools end-to-end. The structures change as deposits thin out towards the edges of the landslide. Here, ridges are shallow at 10 metres high and sit closer together.Co-author, Dr. Tom Mitchell, Associate Professor of Earthquake Geology and Rock Physics (UCL Earth Sciences), said: "The Martian landslide we studied covers an area larger than Greater London and the structures within it are huge. Earth might harbour comparable structures but they are harder to see and our landforms erode much faster than those on Mars due to rain."While we aren't ruling out the presence of ice, we know is that ice wasn't needed to form the long run-outs we analysed on Mars. The vibrations of rock particles initiate a convection process that caused upper denser and heavier layers of rock to fall and lighter rocks to rise, similar to what happens in your home wh ere warmed less dense air rises above the radiator. This mechanism drove the flow of deposits up to 40 km away from the mountain source and at phenomenally high speeds."The research team includes Apollo 17 astronaut, Professor Harrison Schmitt (University of Wisconsin Madison), who walked on the Moon in December 1972 and completed geologic fieldwork while on the lunar surface.Professor Schmitt, said: "This work on Martian landslides relates to further understanding of lunar landslides such as the Light Mantle Avalanche I studied in the valley of Taurus-Littrow during Apollo 17 exploration and have continued to examine using images and data collected more recently from lunar orbit. Flow initiation and mechanisms on the Moon may be very different from Mars; however, comparisons often help geologists to understand comparable features."As on the Earth, the lunar meteor impact environment has modified the surface features of the Light Mantle Avalanche of the 75+ million years since it occurred. The impact redistribution of materials in the lunar environment has modified features that ultimately may be found to resemble those documented in the Martian landslide study."Of additional interest relative to the Light Mantle Avalanche deposit will be the forthcoming examination of a core from the upper 70 cm of the deposit obtained during Apollo 17 exploration. This previously protected core is in the process of being opened and examined by a large consortium of NASA and outside scientists. This important study of a Martian landslide, for the time being at least, has been confined to remotely sensed information."
ЦитатаN.A. написал: Martian landslides not conclusive evidence of iceЧего только не придумают чтобы отрицать реальность.
Цитатаuniversetoday написал:MAY 27, 2019 BY MATT WILLIAMSNew layers of water ice have been found beneath Mars' North PoleOne of the most profound similarities between Earth and Mars, one which makes it a popular target for research and exploration, is the presence of water ice on its surface (mainly in the form of its polar ice caps). But perhaps even more interesting is the presence of glaciers beneath the surface, which is something scientists have speculated about long before their presence was confirmed.These caches of subsurface water could tell us a great deal about Martian history, and could even be an invaluable resource if humans ever choose to make Mars their home someday. According to a recent study by a pair of scientists fr om the Universities of Texas at Austin and Arizona, there are also layers of ice beneath the northern polar ice cap that could be the largest reservoir of water on the planet.The findings were the subject of a study that was recently published in Geophysical Research Letters. The study was led by Stefano Nerozzi, a graduate student from the University of Texas at Austin's Institute of Geophysics (UTIG) and was assisted by Professor Jack Holt of the University of Arizona's Lunar and Planetary Laboratory (LPL).A view of Mars showing the planet's northern polar ice cap. Credit: ISRO/ISSDC /Emily LakdawallaFor the sake of their study, Nerozzi and Prof. Holt relied on data gathered by the Shallow Radar (SHARAD) instrument aboard the Mars Reconnaissance Orbiter's (MRO) - which is capable of penetrating up to 2.4 km (1.5 mi) beneath the surface using radar waves. What they reported was the discovery of several layers of sand and ice roughly 1.6 km (1 mi) beneath Mars' north pole. Скрытый текст: These layers were found to be 90% water in some places, and are believed to be the remnants of ancient polar ice sheets. If melted, the researchers indicate that they would create a global ocean with a depth of at least 1.5 meters (5 feet). As Nerozzi explained in a UT News press release, this find was quite surprising. "We didn't expect to find this much water ice here," he said. "That likely makes it the third largest water reservoir on Mars after the polar ice caps."The findings were corroborated by a separate study (on which Nerozzi was a co-author) that was led by researchers at Johns Hopkins University and also appeared in the Geophysical Research Letters. For this study, the team relied on gravity data to place constraints on the density of the area beneath the polar ice cap. From the low-density readings they obtained, they estimated that the layers ice and sand is more than 50% water overall.This discovery is a boon for scientists since these layers are essentially a record of past climate change, and analysis of them could reveal some very interesting things about the planet's history. In short, the geometry and composition of these layers could help scientists to determine if the Martian climate was ever favorable to life.A composite image showing alternating layers of ice and sand in an area wh ere they are exposed on the surface of Mars, taken with the MRO's HiRISE camera. Credit: NASA/JPL/University of ArizonaAs for how all that water got there, the authors theorize that they formed during past periods of warming and cooling on Mars. Scientists have known for some time glacial events take place on Mars that are driven by variations in the planet's orbit and tilt (much like Earth). Over periods of about 50,000 years, Mars tilts more towards the Sun before gradually returning to an upright position.When Mars sits more upright, the equatorial region warms while the northern polar region cools, causing the ice caps to advance. When the planet tilts towards the Sun, the polar region warms, causing the ice caps to melt. It is during these times that the remnants of the ice caps will become covered in sand, which has historically protected them from exposure to the Sun and dissipating into the atmosphere.Prof. Holt, who was a research professor with the UTIG for 19 years before joining the University of Arizona in 2018, has been a co-investigator with the SHARAD science team since the MRO arrived at Mars in 2006. Using data from this instrument, MRO was also able to confirm the presence of subsurface glaciers around Mars' mid-latitudes. As he stated, this recent find effectively doubles the amount of water ice known to exist on Mars:"Surprisingly, the total volume of water locked up in these buried polar deposits is roughly the same as all the water ice known to exist in glaciers and buried ice layers at lower latitudes on Mars, and they are approximately the same age"The South Pole on Mars. Image: NASA.Previously, scientists thought that the ancient ice caps were lost, but this study reveals that the northern ice sheet has survived under the planet's surface, arranged as alternate bands of ice and sand. This study not only contradicts that assumption but also provides new and important insights into the exchange of water ice between Mars' poles and mid-latitudes.Another exciting possibility is the way that the study of these glaciers could help determine whether Mars was ever habitable. As Nerozzi explained:"Understanding how much water was available globally versus in the poles is important if you're going to have liquid water on Mars. You can have all the right conditions for life, but if most of the water is locked up at the poles, then it becomes difficult to have sufficient amounts of liquid water near the equator."Thanks to a growing number of robotic missions that have been sent to Mars, what we know about the planet has grown by leaps and bounds. And with every new discovery, the need for further exploration becomes apparent. Someday soon, we may augment those efforts by sending human astronauts there, which may even pave the way for human settlement.And when those people arrive, the presence of subsurface glaciers will play a major role in their efforts.Further Reading: UT News, Geophysical Research Letters
Цитата: VAA от 23.07.2020 00:40:03Жаль, приземляться планируется на Utopia Planitia на севере...
Цитата: Старый от 14.07.2020 15:04:47Вулканы тоже ледяные (грязевые).
ЦитатаТайна лавоподобных потоков на Марсе разгадана ученымиhttps://www.astronews.ru/cgi-bin/mng.cgi... Ученые утверждают, что тайна некоторых лавообразных течений на Марсе была вызвана не лавой, а грязью. На поверхности Марса существуют десятки тысяч таких форм рельефа, часто расположенных там, где есть массивные каналы, прорытые в поверхности планеты древними жидкостями, текущими вниз по течению. Эти каналы чрезвычайно длинны, простираясь на многие сотни километров в длину и обычно более чем на десятки километров в ширину. Считается, что они являются результатом массовых наводнений, охватывающих огромные объемы воды, сравнимые с самыми крупными наводнениями, когда-либо имевшими место на Земле. Когда вода просачивается в недра, она может снова появиться в виде грязи. В настоящее время европейская группа исследователей смоделировала движение грязи на поверхности Марса, результаты которого опубликованы в журнале Nature Geoscience. Исследование проводилось под руководством Института геофизики чешской Академии наук совместно с Ланкастерским Университетом, Открытым университетом Резерфорда Эпплтона в Великобритании, CNRS во Франции, DLR и Мюнстерский университет в Германии и CEED в Норвегии. Используя марсианскую камеру в Открытом университете, ученые воссоздали температуру поверхности и атмосферное давление на Марсе в рамках моделирования условий как на Земле, так и на Марсе.
Цитата: Старый от 14.07.2020 15:04:47Вобщем в очередной раз вкраце суть: поверхностный слой Марса толщиной в километры представляет собой грунт с очень большим содержанием льда, по сути "грязный лёд". Сверху он покрыт слоем минерального реголита толщиной в метры. Из этого материала состоят южные кратерированные плато Марса. Все детали рельефа Марса объясняются сублимацией этого льда "с торца", в виде продвигающегося уступа. С северных равнин лёд уже сублимировал. Глобальный уступ это место где процесс сублимации льда продвигается с севера на юг пожирая кратерированные плато и превращая их в северные равнины. Вулканы тоже ледяные (грязевые).
Цитата: NASADec. 10, 2019NASA's Treasure Map for Water Ice on MarsA new paper published in Geophysical Research Letters will help by providing a map of water ice believed to be as little as an inch (2.5 centimeters) below the surface....This rainbow-colored map shows underground water ice on Mars. Cool colors are closer to the surface than warm colors; black zones indicate areas where a spacecraft would sink into fine dust; the outlined box represents the ideal region to send astronauts for them to dig up water ice.Credits: NASA/JPL-Caltech/ASU...Martian water ice is locked away underground throughout the planet's mid-latitudes. ...