View source for Heat Shield Rock

{{short description|Basketball-sized iron-nickel meteorite found on Mars}}
{{Infobox meteorite
|Name                      = Heat Shield Rock
|Alternative names         = Meridiani Planum meteorite
|Image                     = PIA07269-Mars Rover Opportunity-Iron Meteorite.jpg
|Image_caption             = Heat Shield Rock
|Type                      = Iron
|Class                     =
|Clan                      =
|Group                     = Probably [[IAB meteorite|IAB]]
|Grouplet                  = <!-- For groups n<5 -->
|Subgroup                  =
|Structural_classification =
|Parent body               =
|Composition               = 93% Iron, 7% nickel, trace of germanium (~300 ppm) & gallium (<100 ppm)
|Shock                     =
|Weathering                =
|Country                   =
|Region                    = [[Meridiani Planum]]
|Lat_Long                  = {{coord|1.9|S|354.5|E|globe:mars|display=inline,title}}
|Observed_fall             = No
|Fall_date                 =
|Found_date                = January 2005
|TKW                       =
|Image2                    =
|Image2_caption            =
}}
{{Wikinews|Mars Rover’s Basketball-Shaped Discovery Stirs Controversy | Rover finds meteorite on Mars}}

'''Heat Shield Rock''' is a [[Basketball (ball)|basketball]]-sized [[iron-nickel meteorite]] found on the [[Meridiani Planum]] plain of [[Mars]] by the Mars rover [[Opportunity rover|''Opportunity'']] in January 2005.

Informally referred to as "Heat Shield Rock" by the Opportunity research team, the [[meteorite]] was formally named '''Meridiani Planum meteorite''' by the [[Meteoritical Society]] in October 2005 (meteorites are always named after the place where they were found).<ref>The Meteoritical Society, Guidelines For Meteorite Nomenclature, 2.2 Distinctive names [http://www.lpi.usra.edu/meteor/docs/nc-guidelines.htm#s22]</ref>

==Discovery==
''Opportunity'' encountered the meteorite entirely by chance, in the vicinity of its own discarded [[heat shield]] (hence the name).  ''Opportunity'' had been sent to examine the heat shield after exiting the crater [[Endurance (crater)|Endurance]]. This was the first meteorite found on another planet and the third found on another Solar System body{{snd}}two others, the millimeter-sized [[Bench Crater meteorite|Bench Crater]] and [[Hadley Rille meteorite|Hadley Rille]] meteorites, were found on the [[Moon]].

===Analysis===
The rock was initially identified as unusual in that it showed, from the analysis with the [[Mini-TES]] spectrometer, an infrared spectrum that appeared unusually similar to a reflection of the sky.  In-situ measurements of its composition were then made using the [[Alpha particle X-Ray spectrometer|APXS]], showing the composition to be 93% [[Iron]], 7% [[nickel]], with trace amounts of [[germanium]] (~300 ppm) and [[gallium]] (<100 ppm). [[Mössbauer spectroscopy|Mössbauer spectra]] show the iron to be primarily in metallic form, confirming its identity as an iron-nickel [[meteorite]], composed of [[kamacite]] with 5–7% nickel.    This is essentially identical to the composition of a typical [[Iron meteorite#Chemical classification|IAB iron meteorite]] found on Earth.  The surface of the rock shows the ''regmaglypts,'' or pits formed by the ablation of a meteorite during passage through the atmosphere, characteristic of meteorites. The largest dimension of the rock is nearing 31&nbsp;cm.<ref name="Meteorites"/>

No attempt was made to drill into the meteorite using the [[Rock Abrasion Tool]] (RAT), because testing on iron meteorites on [[Earth]] showed that the rover's drilling tools would be abraded and damaged.  The RAT was designed to drill into ordinary rock, not into iron-nickel alloy. [[Meridiani Planum]], the part of Mars where this meteorite was found, is suspected to have once been covered by a layer of material with a thickness of as much as {{convert|1|km}} which has been subsequently eroded. However no evidence suggests when it impacted. To survive impact largely undeformed it must have impacted at less than ~1.5&nbsp;km/s, which sets boundaries on its entry dynamics and Mars' atmosphere at the time it impacted. In any case, the meteorite did not show much sign of [[rust]].  In the absence of detailed knowledge of the Mars environment, it is not possible to conclude whether it fell recently or not.{{citation needed|date=July 2020}}

==Other nickel-iron meteorites found on Mars==
Following the identification of Heat Shield Rock as a meteorite, five similar iron meteorites were discovered by ''Opportunity'' (informally named "[[Block Island meteorite|Block Island]]", "Ireland"<ref name="Meteorites">{{Cite journal |last1=Fairén |first1=A. G. |last2=Dohm |first2=J. M. |last3=Baker |first3=V. R. |last4=Thompson |first4=S. D. |last5=Mahaney |first5=W. C. |last6=Herkenhoff |first6=K. E. |last7=Rodríguez |first7=J. A. P. |last8=Davila |first8=A. F. |last9=Schulze-Makuch |first9=D. | last10 = El Maarry | first10 = M. Ramy |last11=Uceda |first11=Esther R. |last12=Amils |first12=Ricardo |last13=Miyamoto |first13=Hirdy |last14=Kim |first14=Kyeong J. |last15=Anderson |first15=Robert C. |last16=McKay |first16=Christopher P. |doi=10.1111/j.1945-5100.2011.01297.x |bibcode=2011M&PS...46.1832F |title=Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars |journal=Meteoritics & Planetary Science |volume=46 |issue=12 |pages=1832–1841 |date=December 2011|s2cid=140151587 | display-authors = 8|doi-access=free }}</ref> "[[Mackinac Island meteorite|Mackinac Island]]", "[[Oileán Ruaidh (Mars rock)|Oileán Ruaidh]]" and "[[Shelter Island meteorite|Shelter island]]").  Two nickel-iron meteorites were identified by the [[Spirit (rover)|''Spirit'']] rover (informally named "Allan Hills" and "Zhong Shan"). One nickel-iron meteorite has been identified by the [[Curiosity (rover)|''Curiosity'']] rover, tagged "Lebanon."<ref>NASA, [http://mars.jpl.nasa.gov/multimedia/images/?ImageID=6433  Curiosity Finds Iron Meteorite on Mars], July 15, 2014 (accessed September 3, 2014)</ref>  In addition, several candidate stony meteorites have also been identified on Mars.

==Terminology==
The term "[[Martian meteorite]]" usually refers to something entirely different: meteorites on Earth which are believed to have originated from Mars,<ref>{{cite web |url=https://www2.jpl.nasa.gov/snc/ |title=Mars Meteorites |publisher=[[Jet Propulsion Laboratory]] |access-date=2019-11-18 }}</ref> a famous example being [[ALH84001]].<ref>{{cite web|url=http://www.lpi.usra.edu/meteor/metbull.php?sea=alh+84001&sfor=names&ants=&falls=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&phot=&snew=0&pnt=no&code=604|title=Meteoritical Bulletin Database: Allan Hills 84001}}</ref>

==Gallery==
<gallery class="center">
File:Heat Shield Rock 1.jpg
File:Heat Shield Rock.jpg
File:Heat Shield Rock, Mars.jpg
File:Opportunity - meteorito.png
File:Heat Shield Rock2.jpg
</gallery>
{{Wide image |Opportunity Heat Shield.jpg|800px|Area around the heat shield, including the resulting shield point of impact.}}

==See also==
{{div col}}
* {{annotated link|Atmospheric entry}}
* {{annotated link|Block Island meteorite}}
* {{annotated link|Bounce Rock}}
* {{annotated link|Glossary of meteoritics}}
* {{annotated link|List of Martian meteorites}}
* {{annotated link|List of rocks on Mars}}
* {{annotated link|Mackinac Island meteorite}}
* {{annotated link|Oileán Ruaidh (Mars rock)|Oileán Ruaidh meteorite}}
* {{annotated link|Shelter Island meteorite}}
{{div col end}}

==References==
{{reflist}}

==Further reading==
{{refbegin}}
* D. S. Rodionov, ''et al.'', "An Iron-Nickel Meteorite on Meridiani Planum: Observations by MER Opportunity’s Mössbauer Spectrometer," European Geosciences Union; ''Geophysical Research Abstracts, Vol. 7,'' 10242; 1607-7962/gra/EGU05-A-10242 (2005).
* Christian Schröder, ''et al.'', "Meteorites on Mars observed with the Mars Exploration Rovers," ''Journal of Geophysical Research: Planets, v. 113(E6),'' E06S22, {{doi|10.1029/2007JE002990}} (2008).
* A. S. Yen, ''et al.'', "Nickel on Mars: Constraints on Meteoritic Material at the Surface," ''Journal of Geophysical Research: Planets, v. 111,'' E12S11, {{doi|10.1029/2006JE002797}} (2006).
* G. A. Landis, "Meteoric Steel as a Construction Resource on Mars,", ''Acta Astronautica, Vol. 64,'' No. 2–3 (Jan–Feb. 2009).  Presented at the Ninth Space Resources Roundtable, Colorado School of Mines, October 2007 [https://web.archive.org/web/20160623192428/http://www.isruinfo.com/docs/srr9/landis_oct_25.zip presentation], 5.9 mb (powerpoint)
{{refend}}

==External links==
{{Commons category|Heat Shield Rock}}
* [https://web.archive.org/web/20120807005703/http://mars.nasa.gov/ Nasa's Mars Exploration Program]
* [http://www.nasa.gov/vision/universe/solarsystem/mer-011905.html NASA announcement] {{Webarchive|url=https://web.archive.org/web/20200929201459/http://www.nasa.gov/vision/universe/solarsystem/mer-011905.html |date=2020-09-29 }}
* [http://marsrovers.jpl.nasa.gov/mission/status_opportunityAll_2005.html#sol341 NAA ''Opportunity'' Archive: sol-by-sol account of the program and the discovery of Heat Shield Rock] {{Webarchive|url=https://web.archive.org/web/20121016200121/http://marsrovers.jpl.nasa.gov/mission/status_opportunityAll_2005.html#sol341 |date=2012-10-16 }}
* [http://www.jpl.nasa.gov/missions/mer/images.cfm?id=1466 JPL meteorite image] {{Webarchive|url=https://web.archive.org/web/20210211052613/https://www.jpl.nasa.gov/missions/mer/images.cfm?id=1466 |date=2021-02-11 }}
* [http://photojournal.jpl.nasa.gov/catalog/PIA07269 JPL Photojournal entry on meteorite]
* [https://archive.today/20130105044550/http://skyandtelescope.com/news/article_1446_1.asp ''Sky & Telescope'' article]
* [http://www.space.com/missionlaunches/mars_meteor_050120.html Space.com article]
* [http://www.lpi.usra.edu/meteor/metbull.php?code=32789 Article in ''Meteoritical Bulletin'']
* [https://mars.nasa.gov/mer/index.cfm Official Mars Rovers site]
* [http://www.psrd.hawaii.edu/May08/MetsOnMars.html Meteorites Found on Mars] Planetary Science Research Discoveries article.

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[[Category:Rocks on Mars]]
[[Category:Iron meteorites]]
[[Category:Meteorites found on Mars]]
[[Category:Mars Exploration Rover mission]]
[[Category:2005 in science]]