Life on Mars: Difference between revisions
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[[Planetary protection]] of Mars aims to prevent biological contamination of the planet.<ref name="strategy">{{cite book | author1=Committee on an Astrobiology Strategy for the Exploration of Mars | author2=National Research Council | date=2007 | chapter=Planetary Protection for Mars Missions | chapterurl=http://www.nap.edu/openbook.php?record_id=11937&page=95 | pages=95–98 | title=An Astrobiology Strategy for the Exploration of Mars | publisher=The National Academies Press | isbn=978-0-309-10851-5 }}</ref> The main goal is to protect future science experiments, so that they don't find Earth microbes when searching for extant Mars organisms, by preventing human-caused microbial introductions, also called [[forward contamination]]. There is abundant evidence as to what can happen when organisms from regions on Earth that have been isolated from one another for significant periods of time are introduced into each other's environment. Species that are constrained in one environment can thrive – often out of control – in another environment much to the detriment of the original species that were present. In some ways this problem could be compounded if life forms from one planet were introduced into the totally alien ecology of another world.<ref name="Cowing_201304">{{cite web | url=http://astrobiology.com/2013/04/planetary-protection-a-work-in-progress.html | title=Planetary Protection: A Work in Progress | first=Keith | last=Cowing | date=April 11, 2013 | work=Astrobiology }}</ref>
The prime concern of hardware contaminating Mars derives from incomplete spacecraft sterilization of some hardy terrestrial bacteria ([[extremophiles]]) despite best efforts.<ref name="Beaty" /><ref name="Debus">{{cite journal | bibcode=2005AdSpR..35.1648D | title=Estimation and assessment of Mars contamination | last=Debus | first=A. | volume=35 | date=2005 | pages=1648–53 | journal=Advances in Space Research | doi=10.1016/j.asr.2005.04.084 | pmid=16175730 | issue=9}}</ref> Hardware includes landers, crashed probes, end-of-mission disposal of hardware, and hard landing of entry, descent, and landing systems. This has prompted research on survival rates of [[Radioresistance|radiation-resistant microorganisms]] including the species ''[[Deinococcus radiodurans]]'' and genera ''[[Brevundimonas]]'', ''[[Rhodococcus]]'', and ''[[Pseudomonas]]'' under simulated Martian conditions.<ref name="Planetary protection – radiodurans">{{cite journal |bibcode=2010AsBio..10..717D |title=Low-Temperature Ionizing Radiation Resistance of Deinococcus radiodurans and Antarctic Dry Valley Bacteria |last=Dartnell |first=Lewis R. |last2=Hunter |first2=Stephanie J. |last3=Lovell |first3=Keith V. |last4=Coates |first4=Andrew J. |last5=Ward |first5=John M. |volume=10 |date=2010 |pages=717–32 |journal=Astrobiology |doi=10.1089/ast.2009.0439 |pmid=20950171 |issue=7}}</ref> Results from one of these experimental irradiation experiments, combined with previous radiation modeling, indicate that ''[[Brevundimonas]]'' sp. MV.7 emplaced only 30 cm deep in Martian dust could survive the cosmic radiation for up to 100,000 years before suffering 10⁶ population reduction.<ref name="Planetary protection – radiodurans" /> Surprisingly, the diurnal Mars-like cycles in temperature and relative humidity affected the viability of ''Deinococcus radiodurans'' cells quite severely.<ref name="simulation">{{cite journal |bibcode=2007AdSpR..40.1672D |title=Simulation of the environmental climate conditions on martian surface and its effect on ''Deinococcus radiodurans'' | last=de la Vega | first=U. Pogoda | last2=Rettberg | first2=P. | last3=Reitz | first3=G. |volume=40 |date=2007 |pages=1672–7 |journal=Advances in Space Research |doi=10.1016/j.asr.2007.05.022 |issue=11}}</ref> In other simulations,
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== Life under simulated Martian conditions ==
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