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Life On Mars: ALH84001
Celestius writes "This press release from NASA Ames states that 'An international team of researchers has discovered compelling evidence that the magnetite crystals in the martian meteorite ALH84001 are of biological origin,' and moreover that these crystals are not only older than any previously known form of life, but were also definitely formed before the meteor fell to Earth. Skeptics remain, of course, as quoted in this article from today's Chronicle, but suffice to say, NASA seems pretty confident." There's also a report on the BBC as well.
Bullshit. Just because our galaxy has a certain configuration doesn't mean that's the only configuration that can support life. Do you honestly think that life can only occur in the uncharted backwaters of the unfasionable end of the western spiral arm of a particular type of galaxy?
>The star has to be exacly the right size nad exactly the right point in its life
Bullshit. Our sun is about 4.5 billion years old. Life has existed on Earth for better than 3 billion years of that. So the sun has been at "exactly the right point in its life" for 2/3 of its life. Uhmm, right. As for size, the only thing that matters is the luminous intensity at the planet's surface. A larger or brighter star simply requires a larger orbit, thicker atmosphere, or more temperature-tolerant life.
>The planet has to be composed of exactly the right material...
Bullshit. Earth is mostly iron and nickel. The crust is mostly silicon, aluminum, and oxygen. Only one of these elements is important for the basics of life. To produce Earth-like life, the planet needs certain amounts of carbon, hydrogen, nitrogen, oxygen, phosphorus, etc. at the surface. These do not have to be the primary constituents of the planet.
>...be the right size...
Bullshit. Earth-like life requires a certain minumum size, to hold an atmosphere. There is really no definite upper limit on size, though. Life, especially simple life like bacteria, would have absolutely no trouble evolving on a planet 10 times as massive as Earth.
>and be at exactly the right distance from the sun
Bullshit. Again, Earth-like life requires the surface temperature to be within a certain range, but it's hardly exact. The primary requirements are that water be a liquid and proteins hold together against thermal disruption. Known life on Earth exists in temperatures over a range of better than 350 Kelvins. Even if you needed a smaller temperature range, you have 3 variables to adjust. Sun brightness, orbit distance, and atmosphereic reflectiveness. It's not too hard to find a combination of those that will produce the right temperature.
>There has to be a moon at exactly the right distance and exactly the right size
Bullshit. Whose ass did you pull this statement out of? Do you honestly expect me to believe that chemical reactions on Earth's surface are dependant on the luminosity and gravitational pull of the Moon?! At least the other arguments sounded credible before you thought about them. This one's just ridiculous.
>...this is not a troll...
Sure had me fooled.
Bugrit! Millenium hand and shrimp!
Some of the magnetite and pyrrhotite in the Allen Hills meteorite was found in or very close to calcium carbonate globules with surface textures consistent with partial dissolution. While magnetite (Fe3O4) and pyrrhotite (FeS) can be inorganically precipitated under reducing conditions (high pH), these conditions stabilize carbonate.
It is possible that the iron sulfides were created at high pH and then the pH was lowered and the carbonates were partially dissolved; however, under such conditions the pyrrhotite and magnetite would also exhibit some kind of weathering, which is not evident in the samples.
Bacteria, however, are known to exhibit intracellular coprecipitation of iron sulfides and magnetite and extracellular coprecipitation of the same in anaerobic conditions.
See J.L. Kirschvink, A.T. Maine, H. Vali, Science 275, 1629 (1997) for more information.
I don't know if the crystal chains reported today were found in close proximity to carbonate globules, but they came from the same meteorite.
All of the various findings that indicate possible life in ALH84001, from polycyclic aromatic hydrocarbons, to magnetite crystals to the so-called microfossils have possible non-biogenic origins.
The real question is what is more likely -- that a bunch of (generally) incompatible inorganic processes all occurred at approximately the same time and place, or that ancient martian life [of which we have no hard evidence at all] is responsible.
At some point Occam's Razor points to life; I am not sure we are there yet, but every new study of ALH80041 seems to push the balance a little bit further in favor of ancient life on Mars.
That means that the chances of wierd sex with some alien chick with 3 breasts just got so much better.
:)
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