Protecting Mars special regions with potential for life to propagate: Difference between revisions
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}}, both requirements to be satisfied simultaneously. |
}}, both requirements to be satisfied simultaneously. |
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Other environmental factors such as the perchlorates and other chemistry {{refn|name=perchlorates}}, ionizing radiation{{refn|name=ionizing_radiation |
Other environmental factors such as the perchlorates and other chemistry {{refn|name=perchlorates}}, ionizing radiation{{refn|name=ionizing_radiation}} |
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{{quote|'''Finding 3-8''': From MSL RAD measurements, ionizing radiation from GCRs at Mars is so low as to be negligible. Intermittent SPEs can increase the atmospheric ionization down to ground level and increase the total dose, but these events are sporadic and last at most a few (2–5)days. These facts are not used to distinguish Special Regions on Mars.}} |
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{{quote|Over a 500-year time frame, the martian surface could be estimated to receive a cumulative ionizing radiation dose of less than 50 Gy, much lower than the LD90 (lethal dose where 90% of subjects would die) for even a radiation-sensitive bacterium such as E. coli (LD90 of ~200–400 Gy)}} |
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{{quote|'''Finding 3-7''': The martian UV radiation environment is rapidly lethal to unshielded microbes but can be attenuated by global dust storms and shielded completelyby<1 mm of regolith or by other organisms.}} }}, and low atmospheric pressure{{refn|name=pressure|(see 3.4.3. Pressure of<ref name=MarsSpecialRegions2014/>). |
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{{quote|'''Finding 3-6''': Most terrestrial bacteria tested fail to grow below 2500 Pa. However, a small subset of bacteria havenow been identified that can reproduce (on rich hydratedagar media) in a ‘‘martian’’ atmosphere (anoxic, CO2)ataverage martian pressure (700 Pa) and 0°C. This fact isnot used to distinguish Special Regions on Mars.}}}} are not used to restrict special regions, because some Earth microbes tolerate them. The presence of multiple environmental factors simultaneously is also not used to restrict special regions because of the existence of polyextremophiles that can withstand multiple simultaneous extreme conditions{{refn|name=multifactor|(see 3.7. Polyextremophiles: combined effects of environmental stressors of<ref name=MarsSpecialRegions2014/>). |
{{quote|'''Finding 3-6''': Most terrestrial bacteria tested fail to grow below 2500 Pa. However, a small subset of bacteria havenow been identified that can reproduce (on rich hydratedagar media) in a ‘‘martian’’ atmosphere (anoxic, CO2)ataverage martian pressure (700 Pa) and 0°C. This fact isnot used to distinguish Special Regions on Mars.}}}} are not used to restrict special regions, because some Earth microbes tolerate them. The presence of multiple environmental factors simultaneously is also not used to restrict special regions because of the existence of polyextremophiles that can withstand multiple simultaneous extreme conditions{{refn|name=multifactor|(see 3.7. Polyextremophiles: combined effects of environmental stressors of<ref name=MarsSpecialRegions2014/>). |
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{{quote|'''Finding 3-9''': The effects on microbial physiology of more than one simultaneous environmental challenge are poorly understood. Communities of organisms may be able totolerate simultaneous multiple challenges more easily than individual challenges presented separately. What little is known about multiple resistance does not affect our current limits of microbial cell division or metabolism in response to extreme single parameters.}}}}. |
{{quote|'''Finding 3-9''': The effects on microbial physiology of more than one simultaneous environmental challenge are poorly understood. Communities of organisms may be able totolerate simultaneous multiple challenges more easily than individual challenges presented separately. What little is known about multiple resistance does not affect our current limits of microbial cell division or metabolism in response to extreme single parameters.}}}}. |
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