Re: Oxygen on exoplanets

Wasn't it =?iso-8859-15?Q?Se=E1n_Hennessy?= who wrote:
>I've been reading lately about the proposed OWL telescope, which would 
>have sufficient resolution to make direct observations of exoplanets. This 
>would enable scientists to analyse their atmospheres spectroscopically and 
>determine their composition.
>
>Now I understand that the presence of a gas like oxygen would be a strong 
>indicator of the presence of life, since oxygen is very reactive and won't 
>last in the atmosphere unless there is some process constantly 
>replenishing it. Life is obviously such a process, but does anyone know if 
>there are others, already known or speculative? Would the presence of 
>oxygen be enough to allow us to safely infer the presence of life?

I don't know of any such processes, but I've heard that detection of
oxygen and methane in the same atmosphere would be generally accepted as
spectroscopic proof of the presence of life. In the absence of reducing
gasses, like methane, in the atmosphere, it might be possible for oxygen
to last quite a long time. 

In practice, the first such experiments might attempt to detect ozone
rather than oxygen because the spectroscopy is a little easier.

-- 
Mike Williams
Gentleman of Leisure