Editing Europa (moon) (section)

==== Chaos and lenticulae ====
{{See also|List of geological features on Europa}} {{multiple image
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 |footer = Left: surface features indicative of [[tidal flexing]]: lineae, lenticulae and the [[Conamara Chaos]] region (close-up, right) where craggy, 250&nbsp;m high peaks and smooth plates are jumbled together
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Other features present on Europa are circular and elliptical {{Lang|la|lenticulae}} ([[Latin]] for "freckles"). Many are domes, some are pits and some are smooth, dark spots. Others have a jumbled or rough texture. The dome tops look like pieces of the older plains around them, suggesting that the domes formed when the plains were pushed up from below.<ref name="diapir">{{cite journal |last1=Sotin |first1=Christophe |last2=Head |first2=James W. |last3=Tobie |first3=Gabriel |title=Europa: Tidal heating of upwelling thermal plumes and the origin of lenticulae and chaos melting |journal=Geophysical Research Letters |date=April 2002 |volume=29 |issue=8 |pages=74-1–74-4 |doi=10.1029/2001GL013844 |bibcode=2002GeoRL..29.1233S |s2cid=14413348 |url=http://planetary.brown.edu/pdfs/2685.pdf |access-date=12 April 2020 |archive-date=31 July 2020 |archive-url=https://web.archive.org/web/20200731021343/http://planetary.brown.edu/pdfs/2685.pdf |url-status=live }}</ref>

One hypothesis states that these lenticulae were formed by [[diapir]]s of warm ice rising up through the colder ice of the outer crust, much like [[magma chamber]]s in Earth's crust.<ref name="diapir" /> The smooth, dark spots could be formed by [[meltwater]] released when the warm ice breaks through the surface. The rough, jumbled lenticulae (called regions of "chaos"; for example, [[Conamara Chaos]]) would then be formed from many small fragments of crust, embedded in hummocky, dark material, appearing like [[iceberg]]s in a frozen sea.<ref name="Goodman">{{cite journal |last1=Goodman |first1=Jason C. |title=Hydrothermal plume dynamics on Europa: Implications for chaos formation |journal=Journal of Geophysical Research |date=2004 |volume=109 |issue=E3 |pages=E03008 |doi=10.1029/2003JE002073 |bibcode=2004JGRE..109.3008G |hdl=1912/3570 |hdl-access=free }}
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An alternative hypothesis suggests that lenticulae are actually small areas of chaos and that the claimed pits, spots and domes are artefacts resulting from the over-interpretation of early, low-resolution Galileo images. The implication is that the ice is too thin to support the convective diapir model of feature formation.<ref name="thinice">{{cite journal |title=Tidal Heat in Europa: Ice Thickness and the Plausibility of Melt-Through |last1=O'Brien |first1=David P. |last2=Geissler |first2=Paul |last3=Greenberg |first3=Richard |journal=Bulletin of the American Astronomical Society |date=October 2000 |volume=30 |page=1066 |bibcode=2000DPS....32.3802O}}</ref><ref>{{cite book |title=Unmasking Europa |author=Greenberg, Richard |date=2008 |url=https://www.springer.com/astronomy/book/978-0-387-47936-1 |isbn=978-0-387-09676-6 |publisher=Springer + Praxis Publishing |series=Copernicus |pages=205–215, 236 |access-date=28 August 2017 |archive-date=22 January 2010 |archive-url=https://web.archive.org/web/20100122060908/http://www.springer.com/astronomy/book/978-0-387-47936-1 |url-status=live }}</ref>

In November 2011, a team of researchers, including researchers at [[University of Texas at Austin]], presented evidence suggesting that many "[[chaos terrain]]" features on Europa sit atop vast lakes of liquid water.<ref>{{Cite journal |last1=Schmidt |first1=B. E. |last2=Blankenship |first2=D. D. |last3=Patterson |first3=G. W. |last4=Schenk |first4=P. M. |date=November 2011 |title=Active formation of 'chaos terrain' over shallow subsurface water on Europa |url=https://www.nature.com/articles/nature10608 |journal=Nature |language=en |volume=479 |issue=7374 |pages=502–505 |doi=10.1038/nature10608 |pmid=22089135 |bibcode=2011Natur.479..502S |issn=1476-4687}}</ref><ref name="europagreatlakeairhart">{{cite web| title=Scientists Find Evidence for "Great Lake" on Europa and Potential New Habitat for Life| author=Airhart, Marc| date=2011| publisher=Jackson School of Geosciences| url=http://www.jsg.utexas.edu/news/2011/11/scientists-find-evidence-for-great-lake-on-europa/| access-date=16 November 2011| archive-date=18 December 2013| archive-url=https://web.archive.org/web/20131218161411/http://www.jsg.utexas.edu/news/2011/11/scientists-find-evidence-for-great-lake-on-europa/| url-status=live}}</ref> These lakes would be entirely encased in Europa's icy outer shell and distinct from a liquid ocean thought to exist farther down beneath the ice shell. Full confirmation of the lakes' existence will require a space mission designed to probe the ice shell either physically or indirectly, e.g. using radar.<ref name="europagreatlakeairhart"/> Chaos features may also be a result of increased melting of the ice shell and deposition of marine ice at low latitudes as a result of heterogeneous heating.<ref>{{Cite journal |last1=Soderlund |first1=K. M. |last2=Schmidt |first2=B. E. |last3=Wicht |first3=J. |last4=Blankenship |first4=D. D. |date=January 2014 |title=Ocean-driven heating of Europa's icy shell at low latitudes |url=https://www.nature.com/articles/ngeo2021 |journal=Nature Geoscience |language=en |volume=7 |issue=1 |pages=16–19 |doi=10.1038/ngeo2021 |bibcode=2014NatGe...7...16S |issn=1752-0894}}</ref>

Work published by researchers from [[Williams College]] suggests that chaos terrain may represent sites where impacting comets penetrated through the ice crust and into an underlying ocean.<ref name=":0">{{Cite journal|last1=Cox|first1=Rónadh|last2=Bauer|first2=Aaron W.|date=October 2015|title=Impact breaching of Europa's ice: Constraints from numerical modeling: IMPACT BREACHING OF EUROPA'S ICE|journal=Journal of Geophysical Research: Planets|language=en|volume=120|issue=10|pages=1708–1719|doi=10.1002/2015JE004877|s2cid=17563282|doi-access=free}}</ref><ref name=":1">{{Cite journal|last1=Cox|first1=Rónadh|last2=Ong|first2=Lissa C. F.|last3=Arakawa|first3=Masahiko|last4=Scheider|first4=Kate C.|date=December 2008|title=Impact penetration of Europa's ice crust as a mechanism for formation of chaos terrain|url=http://doi.wiley.com/10.1111/j.1945-5100.2008.tb00659.x|journal=Meteoritics & Planetary Science|language=en|volume=43|issue=12|pages=2027–2048|doi=10.1111/j.1945-5100.2008.tb00659.x|bibcode=2008M&PS...43.2027C|s2cid=129700548|access-date=12 January 2021|archive-date=1 October 2021|archive-url=https://web.archive.org/web/20211001064153/https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1945-5100.2008.tb00659.x|url-status=live}}</ref>