SETI bioastro: Fw: A very relevant new Europa paper...

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From: LARRY KLAES (ljk4@msn.com)
Date: Fri Nov 29 2002 - 22:38:08 PST


----- Original Message -----
From: Bruce Moomaw
Sent: Saturday, November 30, 2002 1:37 AM
To: Europa Icepick
Subject: A very relevant new Europa paper...

...from the Nov. 22 "Geophysical Research Letters":

Buck, Leon; Chyba, Christopher F.; Goulet, Marc; Smith, Alex; Thomas,
Paul
Persistence of thin ice regions in Europa's ice crust
10.1029/2002GL016171
22 November 2002

Abstract

Extensive data from planetary spacecraft as well as celestial
mechanics models support the existence of a subsurface ocean on
Europa ~100 km thick, maintained by a tidal heat flux. Models in
which the overlying ice crust is less than 20 km thick permit
breaches in the ice due to impact events or thermal plumes from the
tidally heated core. We apply a two-dimensional thermal model to the
analysis of the refreezing of a hole in the ice crust following a
breach event. Our model incorporates heat produced by tidal heating
of Europa in two ways: a basal heat flux from Europa's silicate and
iron core, together with volumetric heating of the ice shell. We
compare our refreezing timescales to those obtained from a model
where viscous flow in the base of the ice crust fills the hole. We
find that catastrophic breaches in Europa's ice crust may produce
regions of relatively thin ice persisting up to ~1 My. These breaches
are closed by viscous flow when radii are small (<10-50 km) and
by conductive refreezing for larger radii, especially if Europa's
crust has a high basal heat flow due to a hot core. Detection of the
ice/ocean interface by orbital detection of the temperature anomalies
or radar sounding would be most probable in the vicinity of these
events.

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