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rfmcdonaldOver at Halfway Down the Danube, Douglas Muir's reaction to the recent announcement that the presence of methane in the Martian atmosphere might indicate that there is, indeed, life on Mars, is worth noting.
I've always believed--I wanted to believe, actually--that life is abundant among the worlds of the Solar System. I also believe that Earth's biosphere is uniquely productive. Mars is the closest thing to an Earth-like planet but it's a radiation-soaked world with a chill thin atmosphere not by chance, with its mass too little to retain its atmosphere, generate tectonic activity, and produce a protective magnetic field. Life might exist among the clouds of Venus, but given the sueprdense carbon dioxide atmosphere of that world it's safe to say that life on that world is also marginal. As for cold high-pressure water oceans of ice moons like those of Europa and Enceladus, there's only so much energy to go around.
Might worlds in other planetary systems tend likewise? The number of worlds detected by astronomers with wildly elliptical orbits does suggest that the circular orbit that has given Earth's climate some stability might be rare ...
What do you think about life on Mars, and elsewhere, and the possible cosmic scarcity of complex biospheres like Earth's? Does it make you place a higher value on the Earth's biosphere? Do you think that there's enough data to comment meaningfully? Does it matter to you at all?
If there's life on Mars, it's almost certainly tiny -- bacteria, basically -- and subterranean. More interestingly, it's life that's almost totally irrelevant to anything but itself. Life on Earth has totally transformed everything about Earth: the atmosphere, the oceans, plate tectonics, the composition of the crust. Life on Mars, on the other hand, seems to have done nothing to or for Mars; the planet would probably be much the same whether it existed or not. It's just... marginal.
[. . .]
Meanwhile, here's a speculation: what if the Mars model is the norm? If the universe is full of life, yep, sure enough -- and virtually all of it consists of small, marginal groups of microbes barely clinging to existence? And Earth, with its teeming biosphere, wildly disequilibriated atmosphere, and great lumbering multicellular organisms everywhere, is the far far end of the distribution curve?
I've always believed--I wanted to believe, actually--that life is abundant among the worlds of the Solar System. I also believe that Earth's biosphere is uniquely productive. Mars is the closest thing to an Earth-like planet but it's a radiation-soaked world with a chill thin atmosphere not by chance, with its mass too little to retain its atmosphere, generate tectonic activity, and produce a protective magnetic field. Life might exist among the clouds of Venus, but given the sueprdense carbon dioxide atmosphere of that world it's safe to say that life on that world is also marginal. As for cold high-pressure water oceans of ice moons like those of Europa and Enceladus, there's only so much energy to go around.
Might worlds in other planetary systems tend likewise? The number of worlds detected by astronomers with wildly elliptical orbits does suggest that the circular orbit that has given Earth's climate some stability might be rare ...
What do you think about life on Mars, and elsewhere, and the possible cosmic scarcity of complex biospheres like Earth's? Does it make you place a higher value on the Earth's biosphere? Do you think that there's enough data to comment meaningfully? Does it matter to you at all?
