Martian spiders: Difference between revisions

Browse history interactively ← Previous editContent deleted Content addedVisual WikitextInline

Revision as of 00:21, 3 April 2009 editJimmarsmars (talk \| contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers15,210 edits →Causes: added image← Previous edit		Latest revision as of 13:18, 25 September 2017 edit undoAvicBot (talk \| contribs)Bots1,227,735 editsm Bot: Fixing double redirect to Geysers on Mars
(21 intermediate revisions by 9 users not shown)
Line 1:		Line 1:
			#REDIRECT ] {{R from merge}}
	]

	'''Martian "spiders"''' are geological formations thus far unique to the ] of Mars. These structures have not been found in the ] or any other region of Mars to date. They appear as the ] ice cap at the Martian south pole ] into carbon dioxide gas during the Martian spring and the surface below is revealed.

	The formations, when viewed individually, form a round lobed structure reminiscent of a spider web. They generally radiate outward in lobes from a central point.<ref> (''Spiders on Earth and Mars''. AIG News #85, page 21.) </ref> The central point is sometimes, but not always, a crater.<ref> Photographic examples: , , </ref> The formation is similar in its branching appearance to ].

	==Causes==
	It is not yet fully understood how the formations occur, or why they appear to only form in the south polar region. Theories include:
	# Dry venting of carbon dioxide (CO<sub>2</sub>) gas and dust up joints.
	# Head-ward erosion: Fluid derived from sub-surface layers is expelled up fissures eroding joints to create tributaries capped with mud-like material and/or ice.
	# Modified ] model: Structures form as the outside of the flow chills.
	# ]-type sources, and
	# ] pressurizes overlying fluids, expelling mud-like material, hydrothermal fluids or basalt. Other explanations have been offered by ], astrophysicists, astrogeologists and astrobiologists including water erosion in Mars' history <ref> , , </ref>, carbon dioxide / sand geysers <ref> , </ref>

	It has also previously been suggested that these structures had a volcanic cause {{Fact\|date=February 2007}} or were simply warm patches of bare ground, however recent thermal imaging by NASA has revealed that these structures are generally as cold as the dry ice that covers the area during the Martian southern hemispheric winter.<ref> [http://www.jpl.nasa.gov/news/news.cfm?release=2006-100 NASA Findings Suggest Jets Bursting From Martian Ice Cap
	] </ref>

	NASA press release from August 16, 2006 states that an earlier theory proposed that the spots were patches of warm, bare ground exposed as the ice disappeared. However, the camera on ] orbiter, which sees in both ] and ] wavelengths, discovered that the spots are nearly as cold as the carbon dioxide ice, suggesting they were just a thin layer of dark material lying on top of the ice and kept chilled by it.{{Fact\|date=November 2008}} The morphology of these formations appears to be controlled by bedding and local jointing of the rocks; implying that expelled fluids are derived from within a few hundred meters of the surface. Some spider ravines modify, some destroy and others create crust in a dynamic near-surface process that extensively reworks the terrain creating and destroying surface layers. This process is rapid, happening in the space of a few days, weeks or months.<ref> [http://spsr.utsi.edu/articles/ness.pdf Peter K Ness and Greg M Orme. Spider-Ravine Models and Plant-like Features on Mars - Possible Geophysical and Biogeophysical Modes of Origin and Planet-like Features on Mars
	JBIS, Vol. 55, pp.85-108.] </ref>

	<gallery>
	Image:Star burst channels.jpg\|Star burst Channels (Spiders) caused by escaping gas, as seen by ]. Star burst channels, also called spiders, may be about 500 meters in diameter and 1 meter deep

	</gallery>

	==References==
	{{reflist}}

	==See also==
	* ]
	* ]
	* ]
	* ]
	* ]
	* ]
	* ]

	== External links ==
	* photo repository. , ,
	* Papers on Martian "Spiders" , , , , , , ,
	* Sir Arthur C. Clarke on Martian "Spiders" , , , ,
	*

	{{Mars}}

	]
	]

	]

Latest revision as of 13:18, 25 September 2017

Redirect to:

Geysers on Mars

From a merge: This is a redirect from a page that was merged into another page. This redirect was kept in order to preserve the edit history of this page after its content was merged into the content of the target page. Please do not remove the tag that generates this text (unless the need to recreate content on this page has been demonstrated) or delete this page.
- For redirects with substantive page histories that did not result from page merges use {{R with history}} instead.