Detecting Life-bearing Extra-solar Planets with Space Telescopes

Detecting Life-bearing Extra-solar Planets with Space Telescopes
http://fr.arxiv.org/abs/0710.1444

abstract wrote:

One of the promising methods to search for life on extra-solar planets (exoplanets) is to detect life's signatures in their atmospheres. Spectra of exoplanet atmospheres at the modest resolution needed to search for oxygen, carbon dioxide, water, and methane will demand large collecting areas and large diameters to capture and isolate the light from planets in the habitable zones around the stars. For telescopes using coronagraphs to isolate the light from the planet, each doubling of telescope diameter will increase the available sample of stars by an order of magnitude, indicating a high scientific return if the technical difficulties of constructing very large space telescopes can be overcome. For telescopes detecting atmospheric signatures of transiting planets, the sample size increases only linearly with diameter, and the available samples are probably too small to guarantee detection of life-bearing planets. Using samples of nearby stars suitable for exoplanet searches, this paper shows that the demands of searching for life with either technique will require large telescopes, with diameters of order 10m or larger in space.

Hmm.... seems logical. Although that could just show that a planet is habitable, rather than having actual life. Even using this method, it will take some time to find a planet that IS habitable.

Hmm, I've heard, though I'm not sure, that habitability and the capacity to have life depend on each other. For example, if all the life on Earth were to disappear, the free oxygen in the air would react with the various elements present on Earth, and after a while, there would be no more free oxygen. The life is needed to replenish this. Habitability might mean that life is a must.

As for detecting life itself, if you do find free oxygen and free methane in an atmosphere, that's a very good sign that there is life. Neither of those can survive long without being replenished.

The free oxygen in Earth's atmosphere is a byproduct of photosynthesis. Originally, the difference between Earth and Venus was that Earth, being a little further from the sun, got just cold enough to let water condense, despite having a super-thick, carbon dioxide atmosphere.

If life hadn't gotten started, or had but didn't evolve photosynthesis, Earth today would either still be a wet Venus, or a Venus-twin. (Depending on if it had heated up enough to evaporate the oceans — I don't know how warm Earth would be today if it still had a secondary atmosphere.)

Well, all interesting project, although no Earth-sized planet in actual habitable orbit has been detected so far.

Last time somebody said something like that, planets were found around Fomalhaut and HR 8799 four months later. If, four months from now, they announce such a planet, I'm giving you a hug, lol.

More seriously, when are we supposed to find out the complete results of the Mearth survey?

Sirius_Alpha wrote:

Last time somebody said something like that, planets were found around Fomalhaut and HR 8799 four months later. If, four months from now, they announce such a planet, I'm giving you a hug, lol.

More seriously, when are we supposed to find out the complete results of the Mearth survey?

Haha, touchè!

But I'm glad to be mistaken when a new discovery is announced