
Europa's Ocean May Have an Earthlike Chemical Balance - wrongc0ntinent
http://www.nasa.gov/feature/jpl/europas-ocean-may-have-an-earthlike-chemical-balance
======
deepnet
That our current ocean chemistry is shaped by life and Europa's chemistry is
similar could be a datum for a Europaean biology.

Urey & Miller terrestrial biogenesis happened during the Hadean / Archean
transition and their pre-biotic soup had a different chemistry than today.

James Lovelock developed the homeostatic biosphere theory that life shapes its
enviroment at JPL, when hunting for Martian Methane.

From Lovelock and Margulis's Giai paper: "3.2 x 10^9 years, that life has been
present on Earth, the physical and chemical conditions of most of the
planetary surface have never varied from those most favourable for life" [1]

[1]
[http://www.jameslovelock.org/page34.html](http://www.jameslovelock.org/page34.html)

------
datashovel
How confident are scientists that life on Earth began in the conditions of
present-day Earth?

I don't think they were trying to assert this necessarily (that the current
conditions of Europa were necessary and sufficient for life to exist there),
but I just wonder this every time I read about space exploration and the fact
that scientists are seeking planets that have an earth-like atmosphere.

Personally I'd want to know (a) what conditions caused life to begin on earth,
then and only then (b) which planets have, presently or in the past, similar
conditions.

All the talk about looking for earth-like planets to find extraterrestrial
life could be a big waste of time if we eventually learn that present-day
conditions on Earth are not conducive to creating the fundamental building
blocks for life, no matter how good it has been at sustaining it.

UPDATE: Sorry, just noticed I mention atmosphere in my comment. That's a
mistake. I was thinking 'earth-like conditions' (which is more or less what's
mentioned in the article), but I typed atmosphere.

~~~
mnl
They've thought about it. Such questions are kind of funny, because they take
for granted that the scientists' standards are akin to the pop science stuff
that everybody else writes. They aren't, and that is what makes good straw man
arguments.

I submitted yesterday -with little success- a nice talk of Jonathan Lunine
(Cornell) at the Harvard-Smithsonian Center for Astrophysics, here it is
again:
[https://www.youtube.com/watch?v=m_mb59aQblY](https://www.youtube.com/watch?v=m_mb59aQblY)
. This, albeit introductory, is what scientist do.

If you find a planet with an atmosphere rich in free oxygen, you can bet it's
life that has put it there, because we have a pretty good idea about the
abundance of the elements and other scenarios are unlikely. At the beginning
of the Archean, there was no O2 in our atmosphere. All there is now comes from
water, CO2 and photosynthesis. As scientists are usually serious about their
jobs, abiogenesis models take into account the more likely primeval atmosphere
and conditions:
[https://en.wikipedia.org/wiki/Abiogenesis](https://en.wikipedia.org/wiki/Abiogenesis)

What is exciting about the search of life in Europa, Enceladus, maybe Ganymede
and who knows Triton (apparently there's no will to go there ever again), is
that we have very good reasons to assume that at some depth under the ice
crust there are hydrothermal vents like those on Earth. And maybe
chemosynthesis is enough to get things started.

Personally I find that there are more reasons to be excited about Enceladus
than about... let's say Mars.

------
ck2
Wow europa has an atmosphere?

It has less gravity than earth's moon.

(I love how google can now tell me gravity of planets and moons)

~~~
Udo
Not an atmosphere like we know it, more like a wispy and weakly-bound envelope
of outgassed material (probably mostly water vapor). If Earth's moon had
volatile components on its surface it would have this kind of envelope, too.
The term atmosphere may be misleading in this context, because this is not a
stable pressurized reservoir of gas, it needs to be replenished constantly.

~~~
philipov
If Europa is constantly leaking gas, how long before it runs out of fuel, so
to speak?

~~~
Udo
I don't know what the rate of mass loss is (I doubt anyone knows), but most
objects in the solar systems are not static: they gas out but they also
accumulate dust particles. Most of the gas giant moons have been emitting gas
and particles into space since they formed, with most of that matter
eventually falling onto the gas giant itself.

My guess is the loss of volatiles is so slow that it would take many billions
of years until the composition of the moon changes in an appreciable way.

~~~
lolive
Holy cow! So the dust in my living room may come from space. Wow, you have
changed my sweeping experience forever!!!

------
headcanon
This is fascinating. I hope as we discover more about Europa, and with SpaceX
as a potential launch partner, perhaps the proposed lander will get an
accelerated schedule.

