The latest fetish of planetary scientists; "There's an ocean underevery moon!"

On 19/07/2015 23:39, RichA wrote:
On Sunday, 19 July 2015 12:13:49 UTC-4, Chris L Peterson wrote:
On Sun, 19 Jul 2015 17:32:02 +0200, Paul Schlyter
wrote:

My point was that we have much stronger evidence for liquid water
beneath the surface of Europa than we do for such a possibility
anywhere else.

OK, so nobody will drill for water there unless an impact ruptures
the crust and water is exposed... :-)

That would be cool.

I do think that a Europa landing mission is something that is likely
to happen in the next few decades, including a drilling operation. I'd
certainly support that. (And unlike Rich, I understand science

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.

--
Regards,
Martin Brown

On 19/07/2015 17:56, Chris L Peterson wrote:
On Sun, 19 Jul 2015 09:24:53 -0700 (PDT), "Chris.B"
wrote:

Can we safely assume that the pressure at the water "surface" is always at atmospheric pressure?

Assuming a perfectly sealed ocean, beneath a thick, global ice shield:

No. The pressure at the top of the sea would be determined by the
weight of the ice above it- far higher than the effective vacuum at
the moon's surface.

It is also boosted by the growth of ice on the inside of the assumed
sealed ice surface layer. Since solid ice expands when it freezes (a
rare property) the pressure inside the ice encrusted oceans will be very
high limited ultimately by the mechanical tensile strength of the
overlying ice layer which will fracture and seep along fault lines.

How would the pressure of the enclosed water vary with orbital stresses on, or expansion/shrinkage of the icy crust?

Not much, I would think.

I doubt orbital stresses will affect the pressure very much but it may
well affect the internal heating a bit. It will flex the crust in a way
that influences thickness and weaknesses.

http://news.bbc.co.uk/1/hi/sci/tech/449135.stm

Would impact [or drilling] rupture of the ice shield automatically produce geysers?

No. Does a hose extending to the bottom of a pool produce a geyser at
the top?

Yes. The water under the ice will be under a significant pressure.

I though water geysers had been seen on Europa fairly recently last year.

http://www.space.com/23923-europa-wa...n-everest.html

Could a sealed system, without any surface gas exchange, actually support life?

Why not? From a material standpoint, the Earth is essentially a closed
system. Life just needs an energy source.

I have just been down the Boubly potash mine a system sealed for
millions of years until humans started mining it. There are
extremophiles in the deepest parts coming up from even deeper.

They make a living typically by using sulphur redox reactions as an
energy source. There is an exobiology lab colocated with the dark matter
facility looking at the archeobacteria that live in the deep mine and
devising experiments to look for similar things on Mars.

Where would the triggers lie for life to ever evolve in the absence of any external stimulus?

What is an "external stimulus"? In fact, the conditions in a
subsurface liquid ocean might be quite similar to the conditions under
which life developed on Earth.

The same arms race that exists between the initial simple ones that
harness whatever chemical energy sources are available and the next
generation up which eats the primary producers.

Herbivores and carnivores but on a very much smaller scale.

--
Regards,
Martin Brown

On Monday, July 20, 2015 at 3:45:58 AM UTC-4, Martin Brown wrote:
On 19/07/2015 23:39, RichA wrote:

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.


I am certain that you have no idea what "certain" means.

On Mon, 20 Jul 2015 09:05:15 +0100, Martin Brown
wrote:

Would impact [or drilling] rupture of the ice shield automatically produce geysers?

No. Does a hose extending to the bottom of a pool produce a geyser at
the top?

Yes. The water under the ice will be under a significant pressure.

Yes, but that doesn't mean it will be under high pressure at the top
of the hose. The pressure is created by the weight of the ice above,
which is similar to the weight of the same amount of water. So by the
time the water column reaches the surface, the force is balanced.
Indeed, since the ice is less dense than the underlying water, I think
it's likely that the water column will stop rising before it actually
reaches the surface at all.

I though water geysers had been seen on Europa fairly recently last year.

Yes, but we don't need to assume that these come from the subsurface
sea (which is quite far down). More likely, I think, they come from
warm pockets much nearer the surface (as on Earth, where most
volcanoes and all geysers result from hot crustal material, not direct
intrusions or extrusions of the mantle).

wrote:
On Monday, July 20, 2015 at 3:45:58 AM UTC-4, Martin Brown wrote:
On 19/07/2015 23:39, RichA wrote:

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.


I am certain that you have no idea what "certain" means.

I could describe you as pedantic but I'm not certain that's quite the right
word.

On Tuesday, July 21, 2015 at 7:51:05 AM UTC-4, Mike Collins wrote:
wsnell01 wrote:
On Monday, July 20, 2015 at 3:45:58 AM UTC-4, Martin Brown wrote:
On 19/07/2015 23:39, RichA wrote:

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.


I am certain that you have no idea what "certain" means.

I could describe you as pedantic but I'm not certain that's quite the right
word.

You could just f off and mind your own business.

On Sunday, July 19, 2015 at 6:39:42 PM UTC-4, RichA wrote:
On Sunday, 19 July 2015 12:13:49 UTC-4, Chris L Peterson wrote:
On Sun, 19 Jul 2015 17:32:02 +0200, Paul Schlyter
wrote:

My point was that we have much stronger evidence for liquid water
beneath the surface of Europa than we do for such a possibility
anywhere else.

OK, so nobody will drill for water there unless an impact ruptures
the crust and water is exposed... :-)

That would be cool.

I do think that a Europa landing mission is something that is likely
to happen in the next few decades, including a drilling operation. I'd
certainly support that. (And unlike Rich, I understand science

But not English. You say "absolutely certain" when certain IS an absolute.

You have to understand something about peterson. He expects precise language from those he dislikes, while expecting them to automatically know what he means no matter how sloppy his choice of words.

wrote:
On Tuesday, July 21, 2015 at 7:51:05 AM UTC-4, Mike Collins wrote:
wsnell01 wrote:
On Monday, July 20, 2015 at 3:45:58 AM UTC-4, Martin Brown wrote:
On 19/07/2015 23:39, RichA wrote:

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.


I am certain that you have no idea what "certain" means.

I could describe you as pedantic but I'm not certain that's quite the right
word.

You could just f off and mind your own business.

Afraid to use the full word again!
Coward!

On Tuesday, July 21, 2015 at 9:38:02 AM UTC-4, Mike Collins wrote:

Afraid to use the full word again!
Coward!

As I explained to peterson, there might be kids reading this. Spell out what you think the 'f' stands for, coward.

On 7/21/2015 7:02 AM, wrote:
On Tuesday, July 21, 2015 at 7:51:05 AM UTC-4, Mike Collins wrote:
wsnell01 wrote:
On Monday, July 20, 2015 at 3:45:58 AM UTC-4, Martin Brown wrote:
On 19/07/2015 23:39, RichA wrote:

But not English. You say "absolutely certain" when certain IS an absolute.

I am fairly certain that you are wrong.


I am certain that you have no idea what "certain" means.

I could describe you as pedantic but I'm not certain that's quite the right
word.

You could just f off and mind your own business.


Use of the F sharp is "certainly" to be expected when someone from the
welfare class is interrupting a conversation. It's one of the few
things they can do to make themselves feel important.

How sad it must be for Smell to wake up every morning and realize he
will have to spend another day being him.

LdB