南極高原 (火星)
 | 此條目目前正依照其他维基百科上的内容进行翻译。 (2010年12月7日) |
| 南極高原 Planum Australe | |
|---|---|
 火星全球探勘者號拍攝的南極高原 | |
| 经纬 | 83°54′S 160°00′E / 83.9°S 160.0°E |
南極高原(拉丁語：Planum Australe，南方的平原；Planum 是指高海拔的平原或高原)是火星南極的一個高原。延伸範圍的北方界線大約 75°S，中心位置在 83°54′S 160°00′E / 83.9°S 160.0°E。NASA原定以火星極地著陸者號研究當地地質，但在降落過程中在火星大氣層內失去聯絡，任務失敗。
冰帽
南極高原部份區域被由水冰和乾冰組成的永久冰帽覆蓋，厚度約 3 公里。火星南半球冬季時季節性冰帽會覆蓋在永久冰帽上，最北界線可到達 60°S，厚度約 1 公尺[1]。 It is possible that the area of this ice cap may be shrinking due to localized climate change or more widespread global warming.[2]
In 1966, Leighton and Murray proposed that the Martian polar caps provided a store of CO2 much larger than the atmospheric reservoir. However it is now thought that both poles are made mostly of water ice. Both poles have a thin seasonal covering of CO2, while in addition the southern pole has a permanent residual CO2 cap, about 8 to 10 metres thick, that lies on top of the water ice. Perhaps the key argument that the bulk of the ice is water is that CO2 ice isn't mechanically strong enough to make a 3 km thick ice cap stable over long periods of time.[3].
歐洲太空總署的火星快車號探測資料顯示南極高原冰帽可分為三個主要的部份。反照率最高的部份冰帽組成成分約 85% 是乾冰，15% 是水冰。 The second part, where the ice cap forms steep slopes at the boundary with the surrounding plain, is almost exclusively water ice. Finally, the ice cap is surrounded by permafrost fields that extend for tens of kilometres north away from the scarps.[4]
The centre of the permanent ice cap is not located at 90°S but rather approximately 150 kilometres north of the geographical south pole. The presence of two massive impact basins in the western hemisphere - Hellas Planitia and Argyre Planitia - creates an immobile area of low pressure over the permanent ice cap. The resulting weather patterns produce fluffy white snow which has a high albedo. This is in contrast to the black ice that forms in the eastern part of the polar region, which receives little snow.[5]
地表特徵
南極高原可分為兩個區域 - Australe Lingula 和 Promethei Lingula，這兩個區域由以下數個峽谷分隔：Promethei Chasma、Ultimum Chasma、南極峽谷和南極槽溝。理論上認為這些峽谷是因為下降風（katabatic wind）造成[6]。南極高原內最大的撞擊坑是麥克默多撞擊坑。
火星的噴泉
The seasonal frosting and defrosting of the southern ice cap results in the formation of spider-like radial channels carved on 1 meter thick ice by sunlight. Then, sublimed CO2 -and probably water- increase pressure in their interior producing geyser-like eruptions of cold fluids often mixed with dark basaltic sand or mud.[7][8][9][10] This process is rapid, observed happening in the space of a few days, weeks or months, a growth rate rather unusual in geology - especially for Mars. No lander is presently planned to visit the dark dune spots and spider areas.
參見
參考資料
- ^ Phillips, Tony. Mars is Melting. Science @ NASA. [2006-10-20].
- ^ Sigurdsson, Steinn. Global warming on Mars?. RealClimate.org. [2006-10-20].
- ^ Byrne, Shane; Ingersoll, AP. A Sublimation Model for Martian South Polar Ice Features. Science. 14 February 2003, 299 (5609): 1051–1053. PMID 12586939. doi:10.1126/science.1080148.
- ^ Water at Martian south pole. European Space Agency. [2006-10-22].
- ^ Mars' South Pole mystery. Spaceflight Now. [2006-10-26].
- ^ Kolb, Eric J.; Kenneth L. Tanaka. Accumulation and erosion of south polar layered deposits in the Promethei Lingula region, Planum Australe, Mars. The Mars Journal (Mars Informatics Inc.). 2006, 2: 1–9. doi:10.1555/mars.2006.0001.
- ^ NASA Findings Suggest Jets Bursting From Martian Ice Cap. Jet Propulsion Laboratory (NASA). August 16, 2006 [2009-08-11].
- ^ Kieffer, H. H. Mars Polar Science 2000 (PDF). 2000.
|contribution=被忽略 (帮助); - ^ Fourth Mars Polar Science Conference (PDF). 2006.
|contribution=被忽略 (帮助); Editors list列表中的|first1=缺少|last1=(帮助); - ^ Kieffer, Hugh H.; Philip R. Christensen and Timothy N. Titus. CO2 jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap. Nature. 30 May 2006, 442 (7104): 793–796 [2009-09-02]. PMID 16915284. doi:10.1038/nature04945.
