Protecting Mars special regions with potential for life to propagate: Difference between revisions
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(A special region is considered to be "... a region within which terrestrial organisms are likely to propagate, or a region which is interpreted to have a high potential for the existence of extant Martian life forms. Given current understanding, this applies to regions where liquid water is present or may occur." (Reference: COSPAR 2002 & 2005, NASA, 2005))"''}}</ref>. . Based on current understanding, this includes any region with a high enough temperature for Earth organisms to propagate (above -18°C), and with water in a form accessible to them (water activity higher than 0.6) {{refn|name=special_region_def|(see section 7.1.1. Recommended organism-based parameters defin-ing the limits of life, and the requirements for Mars Special Regions, page 940 of<ref name=MarsSpecialRegions2014/>) |
(A special region is considered to be "... a region within which terrestrial organisms are likely to propagate, or a region which is interpreted to have a high potential for the existence of extant Martian life forms. Given current understanding, this applies to regions where liquid water is present or may occur." (Reference: COSPAR 2002 & 2005, NASA, 2005))"''}}</ref>. . Based on current understanding, this includes any region with a high enough temperature for Earth organisms to propagate (above -18°C), and with water in a form accessible to them (water activity higher than 0.6) {{refn|name=special_region_def|(see section 7.1.1. Recommended organism-based parameters defin-ing the limits of life, and the requirements for Mars Special Regions, page 940 of<ref name=MarsSpecialRegions2014/>) |
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{{quote|Conditions on the surface of Mars |
{{quote|Conditions on the surface of Mars are often described as being cold and dry (along with dusty and cratered). As it happens, those conditions are critical to the ability of terrestrial organisms to replicate in any environment. If it is too cold (or too hot) or too dry, terrestrial microbes will not replicate. Thus we define the basic parameters of a Special Region (without margin) as a location where<br> |
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(1) the temperature (T) is 255 K (-18°C) or above (Finding 3-1) and<br> |
(1) the temperature (T) is 255 K (-18°C) or above (Finding 3-1) and<br> |
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(2) water activity (aw) is above 0.60 (Finding 3-4). |
(2) water activity (aw) is above 0.60 (Finding 3-4). |
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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|(see |
Other environmental factors such as the perchlorates and other chemistry {{refn|name=perchlorates}}, ionizing radiation{{refn|name=ionizing_radiation|(see 3.6. Ionizing radiation at the surface page 891 of<ref name=MarsSpecialRegions2014/>). |
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{{quote|'''Finding 2-1''': Modern martian environments may contain molecular fuels and oxidants that are known to support metabolism and cell division of chemolithoautotrophic microbes on Earth}}}}, ionizing radiation{{refn|name=ionizing_radiation|(see 3.6. Ionizing radiation at the surface page 891 of<ref name=MarsSpecialRegions2014/>). |
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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.}} |
{{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)}} |
{{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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