View source for Home Plate (Mars)

{{Short description|Extraterrestrial Plateau}}
{{Infobox feature on celestial object
|name        = Home Plate
|image       = [[Image:PIA09089-RA3-hirise-closeup annotated.png|200px]]
|caption     = [[HiRISE]] image of the "Home Plate" [[rock outcrop]].
|type        = [[Rock outcrop]]
|coordinates = {{coord|14.6|S|175.5|E|globe:mars_type:landmark|display=inline,title}}
}}
'''Home Plate''' is a plateau roughly 90 m across within the [[Columbia Hills (Mars)|Columbia Hills]], [[Mars]]. It is informally named for its similarity in shape to a [[baseball]] [[home plate]]. Home Plate is a rocky outcrop that appears to show layered features.

The plateau has been extensively studied by [[Spirit rover|''Spirit'']], one of the [[Mars Exploration Rover]]s, since 2006. The rover became stuck in loose granular material alongside the northeast side of the plateau. The rover last communicated with Earth on March 22, 2010.<ref>{{cite web|url=http://www.nasa.gov/mission_pages/mer/multimedia/pia15037.html|title=Spirit Remains Silent at Troy|access-date=April 21, 2012|archive-date=November 24, 2012|archive-url=https://web.archive.org/web/20121124045328/http://www.nasa.gov/mission_pages/mer/multimedia/pia15037.html|url-status=dead}}</ref>

==Exploration==
''Spirit'' arrived at Home Plate on [[Timekeeping on Mars|sol]] 744 (February 7, 2006) and has completed a scientific investigation with her robotic arm before moving to Low Ridge Haven due to power concerns. She returned on sol 1126 to resume those studies.

''Spirit'' spent her third Martian winter on Home Plate's north edge.<ref>{{cite web|url=https://www.newscientist.com/article/dn12884-mars-rover-spirit-to-head-north-for-the-winter.html|title=Mars rover Spirit to head north for the winter|author=Maggie McKee|access-date=December 26, 2007}}</ref>
{{Wide image|Sol594A P2281 L257atc-A597R1 br2.jpg|600px|Home Plate (upper center), as seen from the summit of Husband Hill.}}

==Origins==
Scientists now believe that Home Plate is an explosive volcanic deposit. It is surrounded by deposits of [[basalt]], which are believed to have exploded on contact with water. The presence of brine is further supported by the high concentration of [[chloride ion]]s in the surrounding rocks. The presence of [[bomb sag]]s (laminae typically found in beds of volcanish ash) seems to confirm this hypothesis.<ref>{{cite journal|journal=[[Science (journal)|Science]]|title=Pyroclastic Activity at Home Plate in Gusev Crater, Mars|pages=738–742|volume=316|doi=10.1126/science.1139045|date=2007|pmid=17478719|issue=5825|bibcode = 2007Sci...316..738S |last2=Aharonson|first2=O.|last3=Clark|first3=B.C.|last4=Cohen|first4=B. A.|last5=Crumpler|first5=L.|last6=De Souza|first6=P. A.|last7=Farrand|first7=W. H.|last8=Gellert|first8=R.|last9=Grant|first9=J.|last10=Grotzinger|first10=J. P.|last11=Haldemann|first11=A. F. C.|last12=Johnson|first12=J. R.|last13=Klingelhofer|first13=G.|last14=Lewis|first14=K. W.|last15=Li|first15=R.|last16=McCoy|first16=T.|last17=McEwen|first17=A. S.|last18=McSween|first18=H. Y.|last19=Ming|first19=D. W.|last20=Moore|first20=J. M.|last21=Morris|first21=R. V.|last22=Parker|first22=T. J.|last23=Rice|first23=J. W.|last24=Ruff|first24=S.|last25=Schmidt|first25=M.|last26=Schroder|first26=C.|last27=Soderblom|first27=L. A.|last28=Yen|first28=A.|last1=Squyres|first1=S.|author-link1=Steve Squyres|url=https://authors.library.caltech.edu/36849/7/Squyres.SOM.pdf|hdl=2060/20070016011|s2cid=9687521 |hdl-access=free}}</ref>

A patch of 90% pure [[opal]]ine [[silicon dioxide]] was unearthed by ''Spirit'' in the vicinity of Home Plate. The patch is believed to be formed in acidic [[Hot spring|hydrothermal conditions]], which supports the theory that Home Plate is of an explosive volcanic origin. Water is also present as mineral [[hydrate]]s.<ref>{{cite web|url=http://www.nasa.gov/mission_pages/mer/mer-20070521.html|title=Mars Rover Spirit Unearths Surprise Evidence of Wetter Past|access-date=May 30, 2007|archive-date=March 8, 2013|archive-url=https://web.archive.org/web/20130308054606/http://www.nasa.gov/mission_pages/mer/mer-20070521.html|url-status=dead}}</ref><ref>{{cite journal|journal=Science|volume=320|pages=1063–1067|title=Detection of Silica-Rich Deposits on Mars|doi=10.1126/science.1155429|date=2008|pmid=18497295|issue=5879|display-authors=8|last1=Squyres|first1=SW|last2=Arvidson|first2=RE|last3=Ruff|first3=S|last4=Gellert|first4=R|last5=Morris|first5=RV|last6=Ming|first6=DW|last7=Crumpler|first7=L|last8=Farmer|first8=JD|last9=Marais|first9=DJ|last10=Yen|first10=A.|last11=McLennan|first11=S. M.|last12=Calvin|first12=W.|last13=Bell|first13=J. F.|last14=Clark|first14=B. C.|last15=Wang|first15=A.|last16=McCoy|first16=T. J.|last17=Schmidt|first17=M. E.|last18=De Souza|first18=P. A.|bibcode = 2008Sci...320.1063S|s2cid=5228900 }}</ref>

Since 2008, scientists believe that this formation is an example of an eroded, ancient, and extinct [[fumarole]].<ref>{{Cite journal |last=Morris |first=R. V. |last2=Ming |first2=D. W. |last3=Gellert |first3=R. |last4=Yen |first4=A. S. |last5=Clark |first5=B. C. |last6=Graff |first6=T. G. |last7=Arvidson |first7=R. E. |last8=Squyres |first8=S. W. |author9=Athena |author10=CRISM Science Teams |date=2008 |title=The Hydrothermal System at Home Plate in Gusev Crater, Mars: Formation of High Silica Material by Acid-Sulfate Alteration of Basalt |url= |journal=Lunar and Planetary Science |volume=39 |pages=2208 |bibcode=2008LPI....39.2208M |bibcode-access=free}}</ref>

==Gallery==
<gallery class="center">
File:Home plate.JPG|''Spirit'' imager moves towards Home Plate.
File:Bomb sag on Mars.jpg|Bomb sag
File:Home plate anim.gif|Curious rock, "animated" via [[wiggle stereoscopy]].  
</gallery>

==See also==
{{wikinews|Spirit Rover on Mars finds water made 'silica-rich soil'}}
* [[List of rocks on Mars]]

==References==
{{reflist|30em}}

==External links==
*[https://mars.nasa.gov/ Nasa's Mars Exploration Program]
*[https://web.archive.org/web/20051103223725/http://marsrovers.nasa.gov/mission/traverse_maps.html Current position of the Mars rovers] - Home Plate is visible, with ''Spirit''{{'}}s journey around it.
*[http://www.planetary.org/blog/article/00000452/ The Planetary Society Weblog: Home, Sweet Home for ''Spirit''] {{Webarchive|url=https://web.archive.org/web/20060215185421/http://www.planetary.org/blog/article/00000452/ |date=2006-02-15 }}
*[https://mars.nasa.gov/mer/index.cfm Official Mars Rovers site]

{{Features visited by Spirit rover}}
{{Mars}}
{{Portal bar|Solar System}}

[[Category:Rocks on Mars]]
[[Category:Fumaroles]]
[[Category:Mars Exploration Rover mission]]