Alien Life will Most Likely be - Alien

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"Alien Life on Titan Would Stink"
Space.com (April 10, 2010)

"If life does exist on Saturn's intriguing moon Titan, it probably stinks.

"The icy moon has long been seen as a potential spot for extraterrestrial life, but so far, there's no evidence of any living things there.

"And if there were life on Titan, it would likely involve chemicals that are noxious and disgusting to humans, scientists say...."

"...'This idea that you can walk up to the alien ambassador and shake their hand is very unlikely,' said biochemist William Bains of MIT and the Cambridge, England-based Rufus Scientific. He explained that these other worldly life forms would probably be so foreign to us that it might be difficult to recognize them as life, and coming into contact with them could prove hazardous.

"For example, Titan life's metabolism might involve chemical compounds such as phosphine and hydrogen sulfide, which are both foul-smelling gases that are toxic to humans...."

"...Instead of relying on water as a primary ingredient for life, as Earthlings do, Titan's life might have blood based on liquid methane, Bains said. Such a creature couldn't survive on Earth, where methane is a gas at our warmer temperatures.

" 'Their blood would instantly boil then release this great cloud of chemicals, quite a number of which are quite poisonous,' Bains said.

"And instead of using the element carbon to build many of the molecules that make up life, these creatures' chemistry might be based on silicon. While this element is relatively flexible and able to bond with a wide variety of other elements, many of these bonds would be unstable. For example, some compounds that could be present in Titan life would spontaneously burst into flames if exposed to Earth's air...."

I'm not sure that I quite buy the "so foreign to us that it might be difficult to recognize them as life" part of the article. What's described - phosphine, hydrogen sulfide and other substances in liquid methane - would likely enough involve microscopic bags of liquid grouped in larger sacks - like the plants and animals we're familiar with. And fungi and bacteria, for that matter. And yes, I know that plant cells tend to have rather hard walls.

Aliens with different life chemistries most likely wouldn't look like the creatures we're familiar with: but then, neither do the critters found in the Burgess Shale. But we don't have trouble identifying the Burgess Shale menagerie as animals - or maybe plants - but whatever, something living.

Okay: maybe we'll find 'living crystals' or something like Hoyle's Black Cloud: but that's not what the article was discussing.

'Life as We Know It,' Class M Planets and All That

I think there will always be room for stories involving beautiful space princesses and exotic-looking aliens who think 9.8 m/s2 acceleration is 'normal' gravity. And are perfectly comfortable in a 78% nitrogen, 21% oxygen, 0.93% argon, 0.038% carbon dioxide mix at 21 degrees Celsius.

I also think there is room for stories where the alien ambassador needs a portable habitat to survive on Earth. And, likely enough, thinks Earth's air is thin and incredibly toxic: but likes the low gravity. ("Earth May Not Be a "Class M" Planet," Apathetic Lemming of the North (December 5, 2009))

Looks like 'serious' scientists are starting to get their heads around the idea that "life" may not always be quite exactly what we've been studying here for the last few thousand years. That's not entirely fair: a competent biochemist worked out a plausible range of possible 'life chemistries' for a wide range of temperatures quite a few years ago:

"...Actually, the idea that life didn't necessarily need water isn't particularly new. A former professor (of chemistry, apparently) at Boston University put together a pretty good argument for a half-dozen life chemistries that might plausibly work in temperatures ranging from near red-hot to near absolute zero:

1. "Fluorosilicone in fluorosilicone
2. "Fluorocarbon in sulfur
3. "Nucleic acid/protein (O) in water
4. "Nucleic acid/protein (N) in ammonia
5. "Lipid in methane
6. "Lipid in hydrogen
   " 'View from a Height' Isaac Asimov (1963), Lancer Books (p. 63)

"Isaac Asimov might be shaky on the sciences of ecology and physics - at least in his fiction - but that was in his professional field: chemistry. I'm inclined to take his view seriously, that life-as-we-know-it isn't necessarily the only sort. We're #3 on that list, by the way...."
(Apathetic Lemming of the North (March 24, 2010)

Then there are the scenarios where the 'aliens' are the descendants of people who left Earth back when humanity first reached the stars: and who have been away from home for a long time.

But this post is getting rather long. Goodnight.

Related posts:

• "Titan, Life Without Water, and 'Messing With Old Definitions'"
  Apathetic Lemming of the North (March 24, 2010)
• "Well, That's Interesting: Burges Shale Creatures"
  (February 13, 2010)
• "Beautiful Space Princesses, Almost Certainly Not: Flying Whales, Maybe"
  (December 8, 2009)
• "Earth May Not Be a 'Class M' Planet"
  Apathetic Lemming of the North (December 5, 2009)
• "Life on Ceres? Could Be"
  Apathetic Lemming of the North (March 5, 2009)
  Particularly
  Exploding Martians and the Viking Life Experiment