[meteorite-list] Early Mercury Impact Showered Earth

[Rob McCafferty]

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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