[meteorite-list] New Research Shows Impacts From Comet or Asteroids Could Have Created Europa's Chaos Terrain

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 21 Oct 2015 17:32:47 -0700 (PDT)
Message-ID: <201510220032.t9M0WlUX009617_at_zagami.jpl.nasa.gov>


New research shows impacts from comets or asteroids could have created
Europa's chaos terrain

By Mary Dettloff
14 October 2015

What began as Williams College students requesting a new course on planets
and moons nearly 12 years ago has now culminated in a new research paper
showing that impactors, such as comets or asteroids, can penetrate the
frozen surface of Jupiter's moon Europa. The paper has been accepted for
publication in the Journal of Geophysical Research: Planets, a publication
of the American Geophysical Union.

Since 2004, undergraduate students led by Ronadh Cox, professor of geoscience,
have studied the ice-covered surface of Europa, trying to understand the
origins of its chaos terrain: areas that look like crustal breaches, with
icebergs embedded in frozen slush. Cox's students explored various hypotheses
for how these features might have formed, focusing on the possible role
of impacts.

In 2009, student Aaron Bauer, a computer science major, took Cox's planetary
tutorial course and became fascinated with this question. Bauer taught
himself the programming language Fortran so that he could run numerical
simulations to test the hypothesis that comets or asteroids had breached
Europa's ice, exposing the underlying liquid ocean and possibly forming
chaos terrain.

The modeling showed that ice penetration is possible for a range of situations.
 For example, a half-kilometer diameter comet is capable of puncturing
five kilometers of ice, whereas a five-kilometer comet could penetrate
40 kilometers of ice. The research also showed that no matter Europa's
ice thickness, there is an impactor size with geologically reasonable
recurrence that it is likely to breach it. This means that it is likely
that Europa's ice-covered oceans were exposed often in the deep past,
as well as in recent geological time.

Such penetrations would form conduits allowing the transfer of astrobiological
material between the surface and the underlying ocean. Whether or not
this is an important process on Europa - or whether it occurs at all ?
has not been established, but it could be important for Europa's potential
to harbor life.

"How Europa's sub-ice surface ocean communicates with the surface, can
mass and energy be transferred from the exterior to the liquid beneath
and how thick the ice barrier is have been questions at the forefront
of research since the Galileo data in the early 2000s revealed the probable
existence of a liquid water layer," Cox said. "The research conducted
by students about the breaches that occur in the ice could contribute
to a better understanding of how they are caused."

The paper, co-authored by Bauer and Cox, will be presented at a Geological
Society of America meeting in November.
Received on Wed 21 Oct 2015 08:32:47 PM PDT

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