Extraterrestrial microbes

[Maddad]

eburacum45<br />Thank you for finding exactly what we were looking for. Apparently diatomic oxygen as a biomarker could mislead us. The very next paragraph though after the one you quoted suggests that ozone would serve our purpose if used in conjunction with water and carbon dioxide. The follow is that text:<br /><br />"<font color="yellow">Can O3 provide a better one? If O2 is produced thanks to H2O photolysis at high altitude, hydrogenous compounds like H, OH and HO2 are produced which attack very efficiently O3 and prevent its accumulation. The only way to have a significant amount of O3 in the atmosphere spectrum is that O2 is produced at low altitude, e.g. by biological photosynthesis, and that no H2O gets at high altitude where UV are present. Consequently, as on terrestrial planets (Selsis et al., 2002), the simultaneous presence of O3 , H2O and CO2 in the atmosphere appears to be a reliable biosignature. This points out the superiority of O3 as a biosignature with respect to O2.</font><br /><br />I suggest that we continue using diatomic oxygen as a biomarker, but not as final proof of life. Instead we should use it as an exoplanet to focus additional attention for possible life.

 

[mental_avenger]

At the very least, the presence of O₂ would indicate a water world with liquid water. That would also indicate a relatively moderate temperature. We could probably live on such a world better than on a dry airless planet. <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>