Europa energy fluxes

[Robert J. Bradbury]

On Mon, 3 Mar 2003, CHRIS CANTRELL wrote:

> No matter how simple the organisms are, it would be nice to get a DNA
> (or RNA) sequence just to compare to life here on Earth. That assumes,
> of course, that RNA will be the genetic mechanism for Europa too.

Making this argument (seriously) requires a lot of hand-waving.  That is
the point of much of my discussion about forms of "life".  We can't
assume RNA, DNA or even anything close to those molecules without
being very Earth-centric.

> I guess there is no way to get a sequence without bringing something back,
> is there? Can you take enough equipment to perform that test on the
> spot?

It depends strongly on the "density" of life.  There is (using microfluidics
and/or in the future nanotech) no problem producing "microlabs".  So one
only has to send back the "information" (e.g. "I found molecular substance
X and it doesn't look like anything one should consider 'natural'").
Mass Spectrometry machines are becoming very sophisticated and relatively
small now (for example).

The problem will be if the ocean is large and the quantity of life is small.
Then finding it may be a nightmare.


Then Thomas Green [mailto:[EMAIL PROTECTED] wrote:

> Using armchair handwaving, [snip]

Ok, that and a buck-something will get me on the bus in Seattle.  Semi :-;

> Limit energy input and biodiversity decreases.  The further
> u move a cave ecosystem from surface energy, the less diversity of its
> organisms and the more regression occurs in the organisms that manage to
> adapt.

Ok, this sounds reasonable to me but I would like to see some hard
evidence for it.  I suspect we could come up with energy restricted
environments (particularly given the complexity of Europa) where the
lack of resources actually works to increase diversity (different
organisms in different niches).

> How many complex organisms are found in the interior of antartica?  Extend
> this reasoning to what is currently known about Europa.

Doesn't translate -- on the Earth "life" is tuned for specific temperature
ranges.  And the reports I've seen indicate there is plenty of life
in Antarctica but it is currently mostly frozen.  Do we have some bias
that "life" isn't "life" because it is in stasis?

> Unless Europa has gobs of seafloor vents spewing some tasty minerals (which is not
> currently predicted), radiation sputtering is all she has for a primary means of
> generating "food".  To move this food from the surface to the ocean requires
> some efficient subduction, otherwise nutrients come in a rare meltthrough
> event instead of a steady trickle.

Do we know that Europa has no chance of energy left from its energy of formation
and/or internal (presumably radioactive) sources?

I also thought the primary energy source on Europa was gravitational "flexing",
am I wrong about this (perhaps confusing with Io)?

> So start with a sub-par, limited energy source.  Then consider the limited means
> to transport it to the ocean.

If I'm correct about the gravitational "flexing" then it is already "in" the ocean,
but this point does raise a host of questions about how to harvest and use the energy.

> Occam's razor relegates discussions of complex organisms being able to survive on
> Europa as speculation at this point; no expert in biochemistry required.

Depends to a large extent (I think) on how creative "life" can get.

> It's important to remember that despite the vast volume of Europa's ocean,
> it's gonna be *much* more dark and desolate than any environment here
> on our incredible earth.

This point I would generally agree with but I would like to see hard numbers
on the energy fluxes.

Robert




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