Life on Mars: Difference between revisions

{{Life in the Universe}}

 

 

Scientific searches for evidence of life began in the 19th century, and they continue today via telescopic investigations and landed missions. While early work focused on phenomenology and bordered on fantasy, modern [[Models of scientific inquiry|scientific inquiry]] has emphasized the search for [[Water on Mars|water]], chemical [[biosignature]]s in the soil and rocks at the planet's surface, and [[biomarker]] gases in the atmosphere.<ref>{{cite conference|url=https://ntrs.nasa.gov/search.jsp?R=20120003707 |title=The Search for Life on Mars |last=Mumma |first=Michael J. |date=January 8, 2012 |conference=Origin of Life Gordon Research Conference |location=Galveston, TX |deadurl=no |archiveurl=https://web.archive.org/web/20160604111239/https://ntrs.nasa.gov/search.jsp?R=20120003707 |archivedate=June 4, 2016 }}</ref><ref name="NYT-20160912">{{cite news|last=Chang |first=Kenneth |title=Visions of Life on Mars in Earth’s Depths |url=https://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |date=September 12, 2016 |work=[[New York Times]] |accessdate=September 12, 2016 |deadurl=no |archiveurl=https://web.archive.org/web/20160912225220/http://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |archivedate=September 12, 2016 }}</ref> On November 22, 2016, NASA reported finding a large amount of [[Water on Mars|underground ice]] in the [[Utopia Planitia]] region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in [[Lake Superior]].<ref name="NASA-20161122">{{cite web|author=Staff |title=Scalloped Terrain Led to Finding of Buried Ice on Mars |url=http://photojournal.jpl.nasa.gov/catalog/PIA21136 |date=November 22, 2016 |work=[[NASA]] |accessdate=November 23, 2016 |deadurl=no |archiveurl=https://web.archive.org/web/20161124094205/http://photojournal.jpl.nasa.gov/catalog/PIA21136 |archivedate=November 24, 2016 }}</ref><ref name="Register-2016">{{cite web|url=https://www.theregister.co.uk/2016/11/22/nasa_finds_ice_under_martian_surface/ |title=Lake of frozen water the size of New Mexico found on Mars – NASA |publisher=The Register |date=November 22, 2016 |accessdate=November 23, 2016 |deadurl=no |archiveurl=https://web.archive.org/web/20161123120850/http://www.theregister.co.uk/2016/11/22/nasa_finds_ice_under_martian_surface/ |archivedate=November 23, 2016 }}</ref><ref name="NASA-20161122jpl">{{cite web|url=http://www.jpl.nasa.gov/news/news.php?release=2016-299 |title=Mars Ice Deposit Holds as Much Water as Lake Superior |publisher=NASA |date=November 22, 2016 |accessdate=November 23, 2016 |deadurl=no |archiveurl=https://web.archive.org/web/20161123145052/http://www.jpl.nasa.gov/news/news.php?release=2016-299 |archivedate=November 23, 2016 }}</ref>

 

Mars is of particular interest for the study of the origins of life because of its similarity to the early Earth. This is especially so since Mars has a cold climate and lacks [[plate tectonics]] or [[continental drift]], so it has remained almost unchanged since the end of the [[Hesperian]] period. At least two thirds of Mars's surface is more than 3.5 billion years old, and Mars may thus hold the best record of the prebiotic conditions leading to [[abiogenesis]], even if life does not or has never existed there.<ref>{{cite journal |doi=10.1029/RG027i002p00189 |title=The early environment and its evolution on Mars: Implication for life |date=1989 |last=McKay |first=Christopher P. |last2=Stoker |first2=Carol R. |journal=Reviews of Geophysics |volume=27 |issue=2 |pages=189–214|bibcode = 1989RvGeo..27..189M }}</ref><ref name="Fromproto">{{cite journal |bibcode=2007prpl.conf..929G |arxiv=astro-ph/0602008 |title=From Protoplanets to Protolife: The Emergence and Maintenance of Life |last=Gaidos |first=Eric |last2=Selsis |first2=Franck |date=2007 |pages=929–44 |journal=Protostars and Planets V}}</ref> In May 2017, evidence of the [[Earliest known life forms|earliest known life]] [[Evolutionary history of life#Colonization of land|on land]] on Earth may have been found in 3.48-billion-year-old [[geyserite]] and other related mineral deposits (often found around [[hot spring]]s and [[geyser]]s) uncovered in the [[Pilbara Craton]] of [[Western Australia]].<ref name="PO-20170509">{{cite news|author=Staff |title=Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks |url=https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |date=May 9, 2017 |work=[[Phys.org]] |accessdate=May 13, 2017 |deadurl=no |archiveurl=https://web.archive.org/web/20170510013721/https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |archivedate=May 10, 2017 }}</ref><ref name="NC-20170509">{{cite journal|last1=Djokic |first1=Tara |last2=Van Kranendonk |first2=Martin J. |last3=Campbell |first3=Kathleen A. |last4=Walter |first4=Malcolm R. |last5=Ward |first5=Colin R. |title=Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits |url=https://www.nature.com/articles/ncomms15263 |date=May 9, 2017 |journal=[[Nature Communications]] |doi=10.1038/ncomms15263 |accessdate=May 13, 2017 |volume=8 |page=15263 |deadurl=no |archiveurl=https://web.archive.org/web/20170518082609/https://www.nature.com/articles/ncomms15263 |archivedate=May 18, 2017 |bibcode = 2017NatCo...815263D }}</ref> These findings may be helpful in deciding where best to search for [[Abiogenesis|early signs of life]] on the planet Mars.<ref name="PO-20170509" /><ref name="NC-20170509" />

 

The search for Life on Mars past and present is the first of [[NASA]]’S four science goals<ref>Hamilton, V.E., Rafkin, S., Withers, P., Ruff, S., Yingst, R.A., Whitley, R., Center, J.S., Beaty, D.W., Diniega, S., Hays, L. and Zurek, R., [https://mepag.jpl.nasa.gov/reports/MEPAG%20Goals_Document_2015_v18_FINAL.pdf Mars Science Goals, Objectives, Investigations, and Priorities: 2015 Version]</ref>:

This includes the search for evidence of [[Planetary habitability|habitability]], [[taphonomy]] (related to [[fossils]]), and [[organic carbon]] on the planet [[Mars]].<ref name="SCI-20140124a" />

 

 

 

== Early speculation ==