Italian magazine claims Phoenix contaminated Mars with terrestrial bacteria |
Italian magazine claims Phoenix contaminated Mars with terrestrial bacteria |
Sep 1 2008, 05:04 PM
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Member Group: Members Posts: 109 Joined: 20-January 07 From: Milano, ITALY Member No.: 1633 |
I have just read a short story by Alex Saragosa published on issue 1067 (29 Aug 2008, pag. 61) of the italian magazine "il venerdì", a Friday supplement of the major national newspaper la repubblica. The story, titled "I batteri terrestri hanno invaso il pianeta rosso" (terrestrial bacteria have invaded the red planet), claims a group of JPL bilogists analyzed samples from the room where Phoenix was assembled and found 26,000 bacterial cells per square meter from 100 different species, including highly radiation resistant Bacillus pumilis. According to the story, these bacteria may have survived the trip to Mars.
I have never heard anything similar from reliable sources (i.e. anything but la Repubblica) . Any info? Paolo Amoroso -------------------- Avventure Planetarie - Blog sulla comunicazione e divulgazione scientifica
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Sep 3 2008, 07:08 PM
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#2
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Member Group: Members Posts: 401 Joined: 5-January 07 From: Manchester England Member No.: 1563 |
Well this conversations been done to the death on every space forum I've ever looked at, so I won't post again on this thread. The main counter-arguments I'd give you for a near surface habitable zone are:
1:Low temperature bacteria I've covered in the links in my last post, they are actually quite common in some places and survive of tiny amounts of water too contaminated with salts to freeze. 2: The atmospheric pressure at the phoenix site is usually above the triple point pressure for water, and any water present at -20 ( which would need to be saturated with a natural antifreeze such as sodium chloride salt) would have a vapour pressure so low it might persist even below that. The pressure needed to give pure water a liquid phase is only 6.7 millibars, and that can be provided by any atmospheric gas, so the absurdly low partial pressure of water in the martian atmosphere doesn't affect the argument. Although in dry air water will evaporate faster it can still form a liquid phase, and at martian polar temperatures I guess evaporation rates would be low even in bone dry air. 3:Most bacterium would be well protected from UV radiation by only a millimetre of Martian regolith. That leaves whatever chemical nasties might be lurking in the soil, and high energy radiation like cosmic rays. For an example of a species that can survive several extreme conditions at once, including dessication, radiation, and oxidising chemicals I give you the absurdly tough Deinococcus radiodurans, probably the best know polyextremophile but not the only one! I will point out myself, before I'm embarrassed by someone doing it for me, that even if a microbe might survive on mars if introduced to the right spot, conditions may well still be to harsh for it to grow. Hence the critter wouldn't be able to 'go' anywhere, however as some microbes can metabolise and synthesis proteins at -15 deg c, a warm midsummer day at phoenix's location, I wouldn't rule out very slow reproduction entirely. Or as I said above, it's right on the edge of possibility, but we've been surprised by micro organisms before... Edit: I'm sure I've read that there might be a habitable zone in Venus upper cloud layer, but I can't find the article, I'll post a link for you If I can find it. -------------------- |
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Sep 4 2008, 12:35 AM
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#3
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Junior Member Group: Members Posts: 96 Joined: 11-February 04 Member No.: 24 |
I'm sure I've read that there might be a habitable zone in Venus upper cloud layer, but I can't find the article, I'll post a link for you If I can find it. There are altitudes on Venus that border on comfortable, e.g. at 56 km, the pressure is 0.46 bar and the temperature is 18 deg.C. Unfortunately that altitude is in the middle of the sulfuric acid clouds. One could counter argue that there are microbes that LIKE sulfuric acid, e.g. archaea acidophiles. However Venus also has strong atmospheric convection and the whole atmosphere eventually gets convected down to the lower depths where nothing living could survive. This sort of argument also holds for Saturn and Jupiter (atmospheric jellyfish are not really feasible). |
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Sep 4 2008, 01:56 AM
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#4
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Member Group: Members Posts: 350 Joined: 20-June 04 From: Portland, Oregon, U.S.A. Member No.: 86 |
Nothing's feasible until it happens.
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