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- Olympia Undae és un gran territori de dunes sorrenques localitzat a la superfície marciana. Aquest camp de dunes s'hi troba situat proper a la regió polar septentrional del planeta, coneguda com Planum Boreum, i cobreix les longituds compreses entre 100°E i 240°E. El 2006, la sonda Mars Express va detectar en aquests terrenys rics dipòsits d'algeps, el que suggereix que aquesta regió pot haver tingut humitat en algun moment de la seva història. (ca)
- Olympia Undae es un gran territorio de dunas arenosas localizado en la superficie marciana. Dicho campo de dunas se encuentra ubicado próximo a la región polar septentrional del planeta, conocida como Planum Boreum, y cubre las longitudes comprendidas entre 100°E y 240°E. En 2006, la sonda Mars Express detectó en estos terrenos ricos depósitos de aljez, lo cual sugiere que la región debió estar mojada en algún punto de su historia. (es)
- Olympia Undae ist ein riesiges Dünenfeld in der Nordpolregion des Planeten Mars. Dieser extraterrestrische Erg liegt zwischen 78° und 83° nördlicher Breite und umgürtet von 120° bis 240° Länge die Nordpolebene Planum Boreum. Er ist das größte zusammenhängende Dünenfeld auf dem Mars und wird bis zu 1100 Kilometer breit – vergleichbar in seiner Oberflächenausdehnung von 470000 Quadratkilometern mit der Rub al-Chali auf der arabischen Halbinsel, dem bedeutendsten aktiven Erg der Erde. (de)
- Olympia Undae is a vast dune field in the north polar region of the planet Mars. It consists of a broad "sand sea" or erg that partly rings the north polar plateau (Planum Boreum) from about 120° to 240°E longitude and 78° to 83°N latitude. Stretching about 1,100 km (680 mi) across and covering an area of 470,000 km2, Olympia Undae is the largest continuous dune field on Mars. It is similar in size to the Rub' Al Khali in the Arabian Peninsula, the largest active erg on Earth. Olympia Undae lies within the informally named Borealis basin (also called the north polar basin), the largest of three topographic basins that occur in the northern lowlands of Mars. The average elevation in Olympia Undae is about 4,250 m below datum (martian "sea" level). The 19-km-diameter crater Jojutla lies near the geographic center of Olympia Undae at 81.63°N latitude and 169.65°E longitude. This crater was named by Andres Eloy Martinez Rojas, Mexican astronomer and science writer. Unda (pl. undae) is a Latin term meaning water, particularly water in motion as waves. The International Astronomical Union (IAU) adopted the term to describe "undulatory," dune-like features on other planets. Olympia Undae contains a variety of dune forms and wind-related (aeolian) depositional features, including sand sheets, transverse dunes, simple barchan dunes, mega-barchans, and complex barchanoid ridges. All of these dune types occur on Earth too. Barchans are isolated, crescent-shaped dunes with horns that point downwind. They occur is areas where sand supply is moderate to low. Small simple barchan dunes and large mega-barchans are common at the margins of Olympia Undae and in areas where the sand cover is thin. Barchanoid ridges are broad linear to sinuous sand accumulations. They form through the lateral coalition of individual barchans and indicate increasing sand supply. Where sand is abundant, transverse dunes occur; they are commonly defined as long barchaoid ridges with fairly straight segments that are perpendicular to the wind direction. The majority of dunes in Olympia Undae are transverse dunes. Their spacing ranges from 200 to 800 m apart crest to crest, and comparison to terrestrial dunes with similar spacing indicates that they are 10 to 25 m high. On Earth, dunes are produced by saltating grains of sand. The requirement that dunes are produced by saltation allows scientists to determine the likely grain size for the particles making up the dunes in Olympia Undae and other martian dune fields. On Mars, the particle size most easily moved by wind is about 100 μm in diameter (fine sand). The sand in Olympia Undae is extremely dark in color and probably consists of basaltic rock fragments. The surface of Olympia Undae has a strong TES Type 2 spectral signature, indicating that the surface materials consist of basaltic andesite or weathered basalt and/or basaltic glass. In 2005, the OMEGA instrument on the Mars Express orbiter detected high concentrations of gypsum in the eastern portion of Olympia Undae (centered at 244.5°E, 80.2°N). CRISM data from the Mars Reconnaissance Orbiter (MRO) suggests that the gypsum is more concentrated along the crests of dunes than in the interdune hollows. The source of the gypsum is uncertain. Gypsum is an evaporitic mineral that precipitates from saline water; thus, its presence may indicate conditions different from today’s martian environment. The mineral may have formed through the melting of acidic snow, or the melting and discharge of sulfur-rich water from the base of the polar ice cap. However, the presence of gypsum does not necessarily require large surface water bodies (e.g., playa lakes). The mineral could have formed in volcanically heated groundwater in the shallow subsurface and later been exposed and concentrated by wind erosion and winnowing ("eolian mining"). The term Olympia Undae can be the source of some confusion among Mars researchers. The term is used to describe 1) the geographical area described above and the type area for 2) a stratigraphic or geologic map unit (e.g. formation) called the Olympia Undae unit. As a stratigraphic unit, Olympia Undae describes materials that make up the geographic Olympia Undae as well as other sand sheets and dune fields encircling Planum Boreum (e.g., Abalos Undae). The Olympia Undae unit is Amazonian in age. To address some of this confusion, the stratigraphic term Olympia Undae unit has recently been renamed to simply "undae unit," since it encompasses other named dune fields (undae) around Planum Boreum. Another possible source of confusion is the distinction between Olympia Undae and Olympia Planum (formerly, Olympia Planitia). As a geographic area, Olympia Undae refers to the erg that covers a large fraction of Olympia Planum between longitude 120° and 240°E. Olympia Undae and Olympia Planum are not interchangeable terms. Olympia Planum is a broad, plain (and topographic bench) adjacent to Planum Boreum. It is half-domed shaped in profile (cross-section) and slopes southward into the Vastitas Borealis. The Olympia Undae erg covers both the bulk of southern Olympia Planum and part of the northern Vastitas Borealis.
* Olympia Undae dunes, as seen by HiRISE. Two sets of transverse dunes are visible, indicating varying wind direction. Olympia Undae is also known as the North Polar Erg.
* Closeup, color-enhanced image of Olympia Undae dunes with melting/subliming ice-cap fragments. Note Barchan dunes and patterned ground. Width of image is about 1 km/3000 ft.
* CRISM spectral signal for gypsum (polyhydrated sulfates) in Olympia Undae dunes.
* North Polar Gypsum Dunes in Olympia Undae. (en)
- Le Olympia Undae sono una formazione geologica della superficie di Marte, in prossimità del polo nord del pianeta. (it)
- Olympia Undae é uma zona arenosa repleta de dunas localizada próximo à região polar de Planum Boreum cobrindo as coordenadas 120° a 240° longitude leste e de 78° a 83° latitude norte. Em 2006 ricos depósitos de gesso foram detectados nessa região pela Mars Express ainda em órbita, sugerindo que essa região possa ter tido umidade em algum ponto de sua história. (pt)
- 奥林匹亚沙丘群（Olympia Undae）是火星北极地区由广袤的“沙海”或沙漠组成的浩瀚沙丘场，它部分环绕着北极高原，覆盖范围约从东经120度至东经240度，北纬78度到北纬83度，东西横跨约1100公里（英里），所占面积达到47万公里2。奥林匹亚沙丘群是火星上最大的连片沙丘，大小与地球上最大的流动沙漠—阿拉伯半岛的鲁卜哈利沙漠相当。 奥林匹亚沙丘群位于非正式命名的北极盆地（Borealis basin）内，该盆地是火星北部低地三座地形盆地中最大的一座。奥林匹亚沙丘群的平均海拔约低于基准面（火星“海”平面）4250米，其位于北纬81.63度、东经169.65度处的地理中心附近坐落了直径19公里的霍胡特拉陨击坑（Jojutla crater），该撞击坑由墨西哥天文学家和科学作家安德烈斯·埃洛伊·马丁内斯·罗哈斯所命名。 “翁达”（Unda），复数为“翁代”（undae）是一条拉丁术语，意思是水，尤其是呈波浪流动之水。国际天文学联合会采用该术语来描述其他行星上“起伏”的沙丘状特征。奥林匹亚沙丘群包含有多种沙丘形态和与风有关的（风积）地貌，包括沙席、横向沙丘、简单新月形沙丘、巨型新月形沙丘和复合型新月形沙垄等，所有这些沙丘形态也都出现在地球上。 新月形沙丘是孤立的月牙形沙丘，两侧分布有顺风向前伸的沙角。它们发生在砂源量中等至较低的地区；在奥林匹亚沙丘群边缘和沙覆盖较薄的地区，小型简单新月沙丘和巨型新月沙丘很常见；新月形沙垄是宽厚的线性到蜿蜒的砂堆体，它们通过表明沙源量增加的单条沙埂的横向联合形成。在沙子丰裕的地方，会出现横向沙丘，它们通常被定义为线性沙垄，具有垂直于风向的相当笔直部分。奥林匹亚沙丘群的大部分沙丘是横向沙丘，它们间顶到顶的距离从200米到800米不等，通过与地球上有类似间距的沙丘比较，揭示它们的高度大致为10米到25米。 在地球上，沙丘是由沙粒跃移所产生，形成沙丘所需的跳跃使科学家能够测定构成奥林匹亚沙丘群及其他火星沙丘场沙丘的颗粒大小。在火星上，最易被风吹移的颗粒直径约100微米（细沙）。奥林匹亚沙丘群沙子的颜色非常深，可能由玄武岩碎屑构成。奥林匹亚沙丘群表面具有很强的热辐射二型光谱特征，表明表面材质是由玄武安山岩或风化的玄武岩和/或玄武玻璃组成。 2005年，欧空局火星快车号轨道器上的光学与红外矿物光谱仪（OMEGA）在奥林匹亚沙丘群东部（中心位置为东经244.5度、北纬80.2度）检测到高丰度的石膏；来自火星勘测轨道飞行器的侦察成像光谱仪数据则表明，石膏更多地集中在沙丘顶部，而非沙丘间的低洼处，石膏的来源尚不确定。石膏是一种从卤水中析出蒸发岩矿物，因此，它的存在可能表明当时的火星环境条件与今天的不同。这种矿物可能是通过酸性雪的融化，或极地冰盖底部融化和流出的富硫液态水而形成。但是，石膏的存在不一定需要大型地表水体（例如旱湖）。这种矿物可能形成于浅层地表下火山加热的地下水，后经风蚀和风扬而暴露和浓缩。 奥林匹亚沙丘群一词可能引起火星研究人员的一些困惑。该术语用于描述：1）上述地理区域和类型区域；2）一种称为奥林匹亚沙丘群单元的地层学或地质图单元（例如：组），作为一种地层单元，奥林匹亚沙丘群描述了构成奥林匹亚沙丘群区域以及围绕北极高原的其他砂席和沙丘场（如阿瓦洛斯沙丘群）的材质，其地质龄隶属于亚马逊纪。为解决这一困惑，地层学术语的奥林匹亚沙丘群单元最近已更名为简单的“沙丘地单元”，因为它包含了北极高原周围其他已命名的沙丘区（undae）。另一个容易引起混淆的概念是如何区别奥林匹亚沙丘群与奥林匹亚高原（原名奥林匹亚平原）。作为一个地理区域，奥林匹亚沙丘群是指在东经120度到240度之间覆盖了大部分奥林匹亚高原的沙漠；而奥林匹亚高原是一片毗邻北极高原的辽阔平原（山麓阶地），它的剖面（横截面）呈半圆顶状，向南倾斜接入北方大平原。奥林匹亚沙丘群和奥林匹亚高原二者是不可互换的术语，奥林匹亚沙丘群覆盖了奥林匹亚高原南部大部以及北方大平原的北部部分地区。
* 高分辨率成像科学设备显示的奥林匹亚沙丘群，可看到两种代表不同风向的横向沙丘，奥林匹亚山也被称为北极沙漠。
* 带有融化/升华碎冰盖的奥林匹亚沙丘群增强色特写图像，注意新月形沙丘和图案地面，图像宽度约为1公里/3000英尺。
* 紧凑型火星侦察光谱仪显示的奥林匹亚沙丘群中石膏（多水合硫酸盐）的光谱信号。
* 奥林匹亚沙丘群中的北极石膏沙丘。 (zh)
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- Olympia Undae és un gran territori de dunes sorrenques localitzat a la superfície marciana. Aquest camp de dunes s'hi troba situat proper a la regió polar septentrional del planeta, coneguda com Planum Boreum, i cobreix les longituds compreses entre 100°E i 240°E. El 2006, la sonda Mars Express va detectar en aquests terrenys rics dipòsits d'algeps, el que suggereix que aquesta regió pot haver tingut humitat en algun moment de la seva història. (ca)
- Olympia Undae es un gran territorio de dunas arenosas localizado en la superficie marciana. Dicho campo de dunas se encuentra ubicado próximo a la región polar septentrional del planeta, conocida como Planum Boreum, y cubre las longitudes comprendidas entre 100°E y 240°E. En 2006, la sonda Mars Express detectó en estos terrenos ricos depósitos de aljez, lo cual sugiere que la región debió estar mojada en algún punto de su historia. (es)
- Olympia Undae ist ein riesiges Dünenfeld in der Nordpolregion des Planeten Mars. Dieser extraterrestrische Erg liegt zwischen 78° und 83° nördlicher Breite und umgürtet von 120° bis 240° Länge die Nordpolebene Planum Boreum. Er ist das größte zusammenhängende Dünenfeld auf dem Mars und wird bis zu 1100 Kilometer breit – vergleichbar in seiner Oberflächenausdehnung von 470000 Quadratkilometern mit der Rub al-Chali auf der arabischen Halbinsel, dem bedeutendsten aktiven Erg der Erde. (de)
- Le Olympia Undae sono una formazione geologica della superficie di Marte, in prossimità del polo nord del pianeta. (it)
- Olympia Undae é uma zona arenosa repleta de dunas localizada próximo à região polar de Planum Boreum cobrindo as coordenadas 120° a 240° longitude leste e de 78° a 83° latitude norte. Em 2006 ricos depósitos de gesso foram detectados nessa região pela Mars Express ainda em órbita, sugerindo que essa região possa ter tido umidade em algum ponto de sua história. (pt)
- Olympia Undae is a vast dune field in the north polar region of the planet Mars. It consists of a broad "sand sea" or erg that partly rings the north polar plateau (Planum Boreum) from about 120° to 240°E longitude and 78° to 83°N latitude. Stretching about 1,100 km (680 mi) across and covering an area of 470,000 km2, Olympia Undae is the largest continuous dune field on Mars. It is similar in size to the Rub' Al Khali in the Arabian Peninsula, the largest active erg on Earth.
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* CRISM spectral signal for gypsum (polyhydrated sulfates) in Olympia Undae dunes.
* (en)
- 奥林匹亚沙丘群（Olympia Undae）是火星北极地区由广袤的“沙海”或沙漠组成的浩瀚沙丘场，它部分环绕着北极高原，覆盖范围约从东经120度至东经240度，北纬78度到北纬83度，东西横跨约1100公里（英里），所占面积达到47万公里2。奥林匹亚沙丘群是火星上最大的连片沙丘，大小与地球上最大的流动沙漠—阿拉伯半岛的鲁卜哈利沙漠相当。 奥林匹亚沙丘群位于非正式命名的北极盆地（Borealis basin）内，该盆地是火星北部低地三座地形盆地中最大的一座。奥林匹亚沙丘群的平均海拔约低于基准面（火星“海”平面）4250米，其位于北纬81.63度、东经169.65度处的地理中心附近坐落了直径19公里的霍胡特拉陨击坑（Jojutla crater），该撞击坑由墨西哥天文学家和科学作家安德烈斯·埃洛伊·马丁内斯·罗哈斯所命名。 “翁达”（Unda），复数为“翁代”（undae）是一条拉丁术语，意思是水，尤其是呈波浪流动之水。国际天文学联合会采用该术语来描述其他行星上“起伏”的沙丘状特征。奥林匹亚沙丘群包含有多种沙丘形态和与风有关的（风积）地貌，包括沙席、横向沙丘、简单新月形沙丘、巨型新月形沙丘和复合型新月形沙垄等，所有这些沙丘形态也都出现在地球上。
* 高分辨率成像科学设备显示的奥林匹亚沙丘群，可看到两种代表不同风向的横向沙丘，奥林匹亚山也被称为北极沙漠。
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