-----Original Message-----
From: Ro&Ro <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>; [EMAIL PROTECTED]
<[EMAIL PROTECTED]>; [EMAIL PROTECTED] <[EMAIL PROTECTED]>; [EMAIL PROTECTED]
<[EMAIL PROTECTED]>; [EMAIL PROTECTED] <[EMAIL PROTECTED]>;
[EMAIL PROTECTED] <[EMAIL PROTECTED]>; [EMAIL PROTECTED]
<[EMAIL PROTECTED]>
Date: Thursday, April 19, 2001 5:13 AM
Subject: Europa seafloor spreading, mantle convection
>
>
> cc to:
> B. Randall Tufts, LPL
> Richard Greenberg, LPL
> Paul E. Geissler, LPL,
> Robert Pearlman
> Larry Klaes
> [EMAIL PROTECTED]
>
>To: Dr Gregory V. Hoppa, LPL, corresponding author, Science paper
>Re: Science Vol 285, 17 September 1999, p. 1899-1902: Formation of
>Cycloidal Features on Europa.
>
>Dear Greg and colleagues,
>
>I am an Australian microbiologist interested in collaborating with
>LPL/NASA
>concerning the probable location of the Europan equivalent of mid-ocean
>ridges(and potential associated life forms), that will be sought by the
>IcePIC mission to Europa. PLease forgive my emailing to you gentleman
>and please opass on to potentially interested scientists if this
>correspondence has been inappropriately directed by me.
>
>Australian scientists already have a long history of collaboration with
>NASA, via the Honeysuckle Creek and Tidbinbilla Space Tracking Stations
>near Canberra, also briefly via the radio telescope at Parkes NSW, and
>more recently by the involvement of an Australian Astronaut on the Space
>Shuttle. There may also be many other connections of which I am not
>aware.
>
>I am Canberra-raised and I now work in Sydney at the University of
>Sydney Department of Microbiology.
>
>Part of my background is in Physics, though I am now a molecular
>biologist.
>
>I am writing to you out of my interest in exobiology and extremophiles.
>However, what I am proposing is that I might initiate correspondence
>with physicists concerning a unifying theory of mantle convection that
>holds true on any rotating planet or moon. This theory (or more
>correctly hypothesis) relies on tomographic data from Earth and
>photographic data from Tethys (Ithaca Chasma).
>
>As yet it is unpublished but I would be interested in having your
>scientists properly evaluate the calculations and principles involved,
>perhaps leading to publication in a journal that takes theoretical
>papers.
>
>The reason this may be of interest to you is that the hypothesis
>predicts a pole-to-pole volcanic ridge, analogous to the mid atlantic. A
>current melt shadow of this ridge may be what is shown in your Europa
>photographs specifically that near the south pole as discussed in your
>article;
>Science Vol 285, 17 September 1999, p. 1899-1902.
>The other cycloid ridges and cycloid chasms would be old melt shadows of
>the same ridge. These old ridges would have moved after their formation,
>as the spherical ice shell of the moon rotates and yaws randomly.
>
>This idea would not need to conflict with the tidal theory of these
>cracks as I have read them on the website:
>http://www.space.com/scienceastronomy/solarsystem/europa-crack_form916.html
>rather, it may give a reason why the tidal cracks appear perpendicular
>to the poles.
>
>The volcanic ridge is predicted to traverse from pole to pole on one
>side of the planet. There is also predicted a matching chasm, which will
>lie on the opposite line of longitude, this is where the sea floor
>material subducts. On Earth this phenomenon is clear in tomographic
>data. On the Earth's surface the pattern is partially obscured by the
>large size of the aggregated continental material which overlies some of
>the larger features and is resistant to subduction.
>
>The warming of the subsurface ocean may also be a factor in positioning
>the cycloidal features, and this coould perhaps obscuring the lateral
>bihemispheric mantle convection (BLMC) pattern that the hypothesis
>proposes. That would be unfortunate for my chances in forming a
>collaboration because there will be no reason for you to entertain the
>unifying theory unless you can physically see some long chasm along a
>line of longitude on Europa.
>
>Having stated all this, what I am proposing is to test the Earth/Tethys
>unifying hypothesis by using Europa as the test case. The theory only
>holds on planets and moons that have a convecting mantle. A way to test
>the hypothesis would be to have IcePIC aim at this possible sea floor
>spreading ridge. Clearly it will be aiming anyway at such a site, and
>this should happen only after taking into account all of the possible
>locations of this ridge.
>
>My reason for writing therefore is that, if correct, the BLMC unifying
>theory predicts only one ridge which therefore can only be landed on
>(using
>IcePIC or similar) by design rather than luck.
>
>The important point in this discussion is that all parties should be
>heard (even if not taken seriously) because the goal of finding life on
>another body in our solar system is too important a scientific venture
>to exclude valid contributors. We wouldn't want to miss out on finding
>the potential life on Europa after travelling all that way would we? I
>am not assertive about the validity of the unifying theory, but I ask
>that some space geophysicists give it the benefit of the doubt for long
>enough to assess the mathematical validiy of the calculations (simple
>Newtonian equations of viscosity versus convective force, Earth model).
>The boundary conditions are that liquids are incompressible and that the
>planet rotates.
>
>I hope you enjoyed our Olympics, and that you have had a happy Easter
>break. I look forward to any reply that any of you may give.
>
>I have also subscribed just now to europa@klx, and I look forward to
>taking part in any discussion that this email may generate. I am also
>curious to participate in general in any other discussions concerning
>the IcePIC mission which is one of the most adventurous and inspired
>missions of human explorers have ever concocted.
>
>- Yours sincerely,
>
>Bob Moore, Easter Friday 2001
>[EMAIL PROTECTED]
>Department of Microbiology
>University of Sydney
>phone
>(home) 61-2-9558-1938
>(work) 61-2-9351-6044
Dr. Moore:
An abstract by G.M. McMurtry and J.G. Learned at the Nov. 1996 "Europa Ocean
Conference" at the San Juan Capistrano Research Institute ("The Comparative
Oceanography of Europa and Earth: Search Strategies for Active Hydrothermal
Systems and Associated Chemosynthetic Life on the Europa Seafloor") says: "A
conservative approach would first test for the presence of active
hydrothermal venting by monitoring the flux of the highly volatile gases
hydrogen and helium. These gases can permeate through thick ice and their
fluxes should be higher near fractures. On Earth, helium and, in
particular, the helium-3 to helium-4 ratio are very sensitive plume tracers,
extending out horizontally in isopycnic layers for 100 to 1000 km from the
venting source ("Science", Vol. 272, pg. 976-79). Low-level orbiters and
landers equipped with the proper sensors could perform these measurements
with relatie ease, but spatial resolution will be poor and isopycnic
layering would hide the plumes from the surface, as is the case on Earth for
even shallow, erupting submarine volcanoes ("Earth and Planetary Science
Letters", Vol. 107, pg 318-27)."
Still, it might be possible that such helium measurements (made by a mass
spectrometer, which is considered a promising instrument for Europa Orbiter
for other reasons) would at least be spatially sharp enough to test your
theory that Europan seafloor spreading activity is concentrated along one
big ridge. The authors' addresses (as of 1996) were [EMAIL PROTECTED]
and [EMAIL PROTECTED] .
Bruce Moomaw
==
You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED]
Project information and list (un)subscribe info: http://klx.com/europa/
