[meteorite-list] Early Mercury Impact Showered Earth

From: Rob McCafferty <rob_mccafferty_at_meteoritecentral.com>
Date: Thu Apr 6 10:03:50 2006
Message-ID: <20060405214917.90283.qmail_at_web50910.mail.yahoo.com>

Definitely a thought provoking article. There are one
or two things which have nagged me about Mercury and I
see no reason why this article cannot point in the
direction of solving them.


> "We think that Mercury was created from a larger
> parent body that was
> involved in a catastrophic collision

a large
> proto-planet collided with a giant asteroid about
> 4.5 billion years ago,
> in the early years of the solar system.
>
> "Mercury is an unusually dense planet, which
> suggests that it contains
> far more metal than would be expected for a planet
> of its size,"

Now I know I'm not the first to suggest this, ideed, I
got the idea from a professor I studied under.

Could Mercury be an ex-moon of Venus? A large object
hitting Venus creating it in much the same way as we
predict the moon formed?

I've seen a graph of (ln)Spin Angular Momentum vs (ln)
mass of the planets and they all fit on the line bar
the Earth, Venus and Mercury. However, Earth/moon
combined does fit the line, as does Mercury/Venus
combined. Is this a coincidence?

That the moon is drifting out from the earth due to
tidal effects and will one day be lost...The
Venus/Mercury mass ratio has greater parity than
Earth/moon. Could it not be that the same process took
place there and Venus simply lost mercury long ago?

I have never once heard this suggested in the popular
press and they say some pretty "far out" stuff.

Is this a theory which is generally considered
nonsense and if so, why?

In anticipation of far more knowledgable people
telling me the current state of play...

R McC

--- Ron Baalke <baalke_at_zagami.jpl.nasa.gov> wrote:

>
>
http://www.spacedaily.com/reports/Early_Mercury_Impact_Showered_Earth.html
>
> Early Mercury Impact Showered Earth
> SpaceDaily
> April 5, 2006
>
> Leicester, England (SPX) - New computer simulations
> of Mercury's formation
> show some of the resulting ejected material ended up
> on Earth and Venus. The
> simulations, which track the material's path over
> several million years, also
> shed light on why Mercury is denser than expected.
>
> Scientists at University of Bern, Switzerland,
> produced the simulations,
> which depict the fate of material blasted out into
> space when a large
> proto-planet collided with a giant asteroid about
> 4.5 billion years ago,
> in the early years of the solar system.
>
> "Mercury is an unusually dense planet, which
> suggests that it contains
> far more metal than would be expected for a planet
> of its size," said
> team leader Jonti Horner, who presented the research
> at a meeting of the
> Royal Astronomical Society.
>
> "We think that Mercury was created from a larger
> parent body that was
> involved in a catastrophic collision, but until
> these simulations we
> were not sure why so little of the planet's outer
> layers were
> re-accreted following the impact."
>
> To solve the problem, the team ran two sets of
> large-scale computer
> simulations. The first examined the behavior of the
> material in both the
> proto-planet and the incoming asteroid. The
> simulations were among the
> most detailed to date, following a huge number of
> particles and
> realistically modeling the behavior of different
> materials inside the
> two bodies.
>
> At the end of the first simulations, a dense
> Mercury-like body remained,
> along with a large swathe of rapidly escaping
> debris. The trajectories
> of the ejected particles were then fed in to a
> second set of simulations
> that followed the motion of the debris for several
> million years.
>
> A second simulation tracked the ejected particles
> until they landed on a
> planet, were thrown into interstellar space, or fell
> into the Sun. The
> results revealed how much material would have fallen
> back onto Mercury
> and allowed the researchers to investigate ways that
> debris is cleared
> within the solar system.
>
> The group found that the fate of the debris depended
> on where Mercury
> was hit, in terms of its orbital position and the
> angle of the
> collision. Prevailing gravitational theory suggested
> a large fraction of
> the debris eventually would fall back onto the
> planet, but the
> simulations showed it would take up to 4-million
> years for 50 percent of
> the ejecta to return to Mercury, enough time for
> much of it to be
> carried away by solar radiation.
>
> This explains why Mercury retained a much smaller
> proportion than
> expected of the material in its outer layers, Horner
> explained. He said
> the simulations also showed a small fraction of the
> ejected material
> made its way to Venus and Earth - a finding that
> illustrates how easily
> material can be transferred among the inner planets.
>
> Given the amount of material that would have been
> ejected in such a
> catastrophe, Horner said, Earth could contain as
> much as 16 quadrillion
> tons of proto-Mercury particles.
>
> Related Links
> RAS 2006 <http://www.nam2006.le.ac.uk/index.shtml>
> Royal Astronomical Society <http://www.ras.org.uk/>
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>


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Received on Wed 05 Apr 2006 05:49:17 PM PDT