Exobiology in the Solar System & The Search for Life on Mars - ESA
Exobiology in the Solar System & The Search for Life on Mars - ESA
Exobiology in the Solar System & The Search for Life on Mars - ESA
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Measurements with <str<strong>on</strong>g>the</str<strong>on</strong>g> Mössbauer <str<strong>on</strong>g>in</str<strong>on</strong>g>strument will be d<strong>on</strong>e by plac<str<strong>on</strong>g>in</str<strong>on</strong>g>g it aga<str<strong>on</strong>g>in</str<strong>on</strong>g>st<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> sample. Physical c<strong>on</strong>tact is required <str<strong>on</strong>g>in</str<strong>on</strong>g> order to m<str<strong>on</strong>g>in</str<strong>on</strong>g>imise possible microph<strong>on</strong>ic<br />
noise <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> velocity-modulated energy of <str<strong>on</strong>g>the</str<strong>on</strong>g> emitted gamma-rays. <str<strong>on</strong>g>The</str<strong>on</strong>g> field of view<br />
is circular (diameter about 1.5-2 cm). <str<strong>on</strong>g>The</str<strong>on</strong>g> average <str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>for</str<strong>on</strong>g>mati<strong>on</strong> depth <str<strong>on</strong>g>for</str<strong>on</strong>g> Mössbauer<br />
data is of <str<strong>on</strong>g>the</str<strong>on</strong>g> order of 100-200 mm, assum<str<strong>on</strong>g>in</str<strong>on</strong>g>g basaltic rock compositi<strong>on</strong>. <str<strong>on</strong>g>The</str<strong>on</strong>g> thickness<br />
of dust layers as found <strong>on</strong> rocks dur<str<strong>on</strong>g>in</str<strong>on</strong>g>g <str<strong>on</strong>g>the</str<strong>on</strong>g> Vik<str<strong>on</strong>g>in</str<strong>on</strong>g>g and Pathf<str<strong>on</strong>g>in</str<strong>on</strong>g>der missi<strong>on</strong>s may<br />
exceed this. To get at least some <str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>for</str<strong>on</strong>g>mati<strong>on</strong> from a possible wea<str<strong>on</strong>g>the</str<strong>on</strong>g>r<str<strong>on</strong>g>in</str<strong>on</strong>g>g r<str<strong>on</strong>g>in</str<strong>on</strong>g>d and <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
host rock, <str<strong>on</strong>g>the</str<strong>on</strong>g> dust needs to be removed by appropriate devices. Measurements be<str<strong>on</strong>g>for</str<strong>on</strong>g>e<br />
and after dust removal should be per<str<strong>on</strong>g>for</str<strong>on</strong>g>med.<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> Mössbauer parameters are temperature-dependent. Especially <str<strong>on</strong>g>for</str<strong>on</strong>g> small<br />
particles exhibit<str<strong>on</strong>g>in</str<strong>on</strong>g>g superparamagnetic behaviour (e.g. nanophase Fe-oxides, which<br />
may be of biogenic orig<str<strong>on</strong>g>in</str<strong>on</strong>g>), <str<strong>on</strong>g>the</str<strong>on</strong>g> Mössbauer spectrum may change drastically with<br />
temperature. <str<strong>on</strong>g>The</str<strong>on</strong>g> observati<strong>on</strong> of such changes will help <str<strong>on</strong>g>in</str<strong>on</strong>g> determ<str<strong>on</strong>g>in</str<strong>on</strong>g><str<strong>on</strong>g>in</str<strong>on</strong>g>g <str<strong>on</strong>g>the</str<strong>on</strong>g> nature of<br />
<str<strong>on</strong>g>the</str<strong>on</strong>g> ir<strong>on</strong>-bear<str<strong>on</strong>g>in</str<strong>on</strong>g>g phases. <str<strong>on</strong>g>The</str<strong>on</strong>g>re<str<strong>on</strong>g>for</str<strong>on</strong>g>e, Mössbauer measurements at different temper-<br />
team II: <str<strong>on</strong>g>the</str<strong>on</strong>g> search <str<strong>on</strong>g>for</str<strong>on</strong>g> chemical <str<strong>on</strong>g>in</str<strong>on</strong>g>dicators of life/II.5<br />
Fig. II.5.7.4/1. Backscatter Mössbauer spectra<br />
of martian analogues obta<str<strong>on</strong>g>in</str<strong>on</strong>g>ed with MIMOS II.<br />
From top to bottom: HWMK600, palag<strong>on</strong>itic<br />
tephra sample from Mauna Kea; HWMK24,<br />
jarositic tephra sample from Mauna Kea;<br />
BCS-301, chemical standard derived from an<br />
ir<strong>on</strong> ore deposit; AKB-1, amygdaloidal basalt<br />
from <str<strong>on</strong>g>the</str<strong>on</strong>g> Keweenawan pen<str<strong>on</strong>g>in</str<strong>on</strong>g>sula;<br />
MAN-74-342A, impact melt rock from <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
Manicouagan crater <str<strong>on</strong>g>in</str<strong>on</strong>g> Canada. (Morris et al.,<br />
1998) (Courtesy G. Kl<str<strong>on</strong>g>in</str<strong>on</strong>g>gelhöfer)<br />
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