Re: Heat

[Bruce Moomaw]

----- Original Message -----
From: "Leonard DiFrancesco" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, October 31, 2002 5:53 PM
Subject: Heat


>
> Consideration of the amount of heat required to melt the ice question:
> In the calculation of the amount of heat required was it considered that
as
> the probe descends from the surface the stress increases in a linear
fashion
> = density of ice X depth.  Thus, as the ice melts and the bonds break, the
> ice will strain and new ice will continue to move in the direction of the
> probe until the maximum deformation, as a function of depth.  What will be
> the pore water pressure around the probe?  What will happen at the
water-ice
> interface?

The pressure of the ice will be similar to that which the probe would
encounter in a comparably deep layer of liquid water -- actually slightly
less, since ice's density is only 97% that of water.  Since Europa's gravity
is only 13.5% of Earth's, the pressure at 20 km depth of (uncontaminated)
ice on Europa equals that at a depth of 1.31 km in uncontaminated Earth
liquid water.  However, the evidence is growing that Europa's ice and water
may be VERY briny -- perhaps as much as 30% various salts by weight -- and
that, of course, would substantially increase its density and thus its
pressure.

As for the meltwater space around a Cryobot: the pressure will be similar
all around it -- so there will be virtually no mechanical pressure trying to
squeeze the Cryobot back up out of the hole.


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