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

Even Pluto now. Even here on Earth, most drilled oil and water wells are failures. Imagine if they spend $5 billion to send a drill to say Europa, and they find nothing?

On Sat, 18 Jul 2015 20:59:52 -0700 (PDT), RichA
wrote:

Even Pluto now. Even here on Earth, most drilled oil and water wells are failures. Imagine if they spend $5 billion to send a drill to say Europa, and they find nothing?

That there's water below the surface of Europa is almost certain. I
don't think anybody will invest too much in drilling anywhere else
without better evidence, though.

On Sat, 18 Jul 2015 23:28:46 -0600, Chris L Peterson
wrote:
That there's water below the surface of Europa is almost certain. I
don't think anybody will invest too much in drilling anywhere else
without better evidence, though.

Isn't "almost certain" the best evidence you can get without actually
drilling there?

On Sun, 19 Jul 2015 13:54:00 +0200, Paul Schlyter
wrote:

On Sat, 18 Jul 2015 23:28:46 -0600, Chris L Peterson
wrote:
That there's water below the surface of Europa is almost certain. I
don't think anybody will invest too much in drilling anywhere else
without better evidence, though.

Isn't "almost certain" the best evidence you can get without actually
drilling there?

No. You could be absolutely certain (for example, if an impact
ruptured the crust, exposing the underlying water to direct
observation).

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.

On Sun, 19 Jul 2015 08:56:08 -0600, Chris L Peterson
wrote:
On Sun, 19 Jul 2015 13:54:00 +0200, Paul Schlyter
wrote:

On Sat, 18 Jul 2015 23:28:46 -0600, Chris L Peterson
wrote:
That there's water below the surface of Europa is almost
certain. I
don't think anybody will invest too much in drilling anywhere
else
without better evidence, though.

Isn't "almost certain" the best evidence you can get without
actually
drilling there?

No. You could be absolutely certain (for example, if an impact
ruptured the crust, exposing the underlying water to direct
observation).

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... :-)

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, so if
they "found nothing", that would be exciting, too.)

On Sunday, 19 July 2015 17:32:07 UTC+2, Paul Schlyter wrote:

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

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:

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

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

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

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

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.

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.

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?

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.

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.

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.

On Sun, 19 Jul 2015 15:39:40 -0700 (PDT), RichA
wrote:

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.

Certainty comes in degrees. It's an adjective that can be qualified,
and in normal English, regularly is.