
Where In Our Solar System Are We Most Likely To Find Life? - thealexknapp
http://www.forbes.com/sites/ethansiegel/2015/09/25/where-in-our-solar-system-are-we-most-likely-to-find-life/
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heeton
Earth

Sorry. Couldn't resist :)

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NietTim
Nah. It's an incredibly stupid title.

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SideburnsOfDoom
Spoiler: Mars is at number 3.

And we know that Mars is slim pickings as far as life goes.

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WalterBright
What we should be doing is terraforming Mars with life from Earth, not
sterilizing everything we send there.

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ckozlowski
Compared to Earth, we know very little about Mars. Purposefully contaminating
our craft (or worse, starting any sort of terraforming operations now) before
we fully understand the planet would make efforts destined for failure at
best, and produce unforeseen consequences for the planet at worst.

We've attempted similar things here on Earth in the past without fully
understanding the consequences, with the ecological disasters to show for it.

Better for us to more fully understand that planet first.

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WalterBright
I doubt a better understanding can happen without sending humans, and there's
no way to put humans about Mars without also releasing Earth life. Do you
oppose a manned mission to Mars?

Besides, there's still zero evidence of life on Mars. There's no ecology to
disrupt.

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simonh
That's been trivially falsified by the tremendous leaps in our understanding
of the planet from each successive probe we've sent. For example, we only
recently got indications of the likely presence of significant quantities of
perchlorates in Martian soils, which has dramatic consequences for any
possible effort at terraforming.

As for 'no ecology', we're a very long way from being in any position to say
that.

Edit: I can't reply to WalterBright's comment, so I'll reply here. I didn't
talk about having to prove anything. It's a matter of balance of evidence.
What percentage of the possible biomes on Mars have we tested and how
thoroughly did we test them? I'd argue less than 10% of the most life-hostile
biomes and those only cursorily. That's way too low a fraction to have any
confidence that Mars is dead. Sure, we can't test every grain of sand on the
whole planet, we have to draw the line somewhere, but for now we've barely
scratched a small part of the surface.

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netcan
These are the definitions of the Drake Equation:

    
    
       R* = the average rate of star formation in our galaxy
       fp = the fraction of those stars that have planets
       ne = the average number of planets that can potentially support life per star that has planets
       fl = the fraction of planets that could support life that actually develop life at some point
       fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
       fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
       L = the length of time for which such civilizations release detectable signals into space[8][9]
    

I think the most interesting thing is as a sort of a map of human knowledge.
Fill in the blanks with your best answer at this point.

We know some stuff about some of these, but very little about others. I think
we can make sensible guesses at the first three, and the last two and Drake's
Equation allows us a large margin of error. The likelihood of life developing
and the likelihood of intelligence developing however… we don't have much. A
weird thing about both these things is that we are the only example we know
of. Even earth, which has demonstrated an ability to develop both, seems to
have done both only once. All life on earth shares an ancestry. Intelligence
is debatable, but by a definition that carries the potential to build
technology proving its intelligence to extra terrestrials we are the only
example.

We can be reasonably certain that if we start from Eukaryotic life, eyes will
evolve. Technology building and intergenerational knowledge accumulation is
less certain. Even if you start with humans, it's not obvious that technology
will evolve. Homo existed for quite a while, even with individuals very
similar to us before getting on this technology curve. Thousands of
generations (or tends of thousands, depending on your definitions) of being
smart, social bipedal apes anatomically similar to us with no apparent
evidence that the invention of pornography-capable smartphones are
forthcoming.

We have similarly little evidence about life's chances of emerging. Some sort
of replication process that has evolutionary potential would be a decent
definition in this context. How likely is that? Do we actually need the
"ingredients" common to Europa and Earth? Is Earth's "ingredient list" even
ideal? Is organic chemistry the only way to do things? I think our ongoing
invention of complex machines is, perhaps, a counterexample.

Back to the Drake equation, I think any time we can fill in one of the
variables, tighten up our margins of error or otherwise add knowledge to this
knowledge map, we are making interesting progress.

TLDR: At this point in time the existence of both life and intelligence must
be assumed to involve ancient, god-like extraterrestrials.

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xlm1717
>TLDR: At this point in time the existence of both life and intelligence must
be assumed to involve ancient, god-like extraterrestrials.

Surprisingly, that assumption (and that it must be assumed) is a touchy
subject at this point in time.

