A closer Mars orbit as the cause of its early "warm, wet period."

Posted to uplink.space.com:


exoscientist
dust
10/25/04 10:42 PM
A closer Mars orbit as the cause of its early "warm, wet period." [
exoscientist]


In reply to:
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Planetary accretion in the inner Solar System [ AlexBlackwell]

Thanks for the link. This reminds me of research on the position of
planets at their formation and where they wind up:

Moving the Orbits of Planets
http://www.ifa.hawaii.edu/faculty/je...b/migrate.html

This notes that present theories suggest some planets moved outwards
while others moved inwards. There is also a paper on the outwards
migration of Neptune in the August issue of Icarus.
I wonder if this can explain the "faint-Sun paradox" in regards to the
Earth and Mars.
This is the problem that the Sun was supposed to be significantly
fainter early in the life of the Solar System but both Earth and Mars
show signs of liquid water carved channels at this early time.
This is a big part of the justification for the viewpoint of some Mars
scientists that Mars was cold and dry early in its history because
theories that propose greenhouse heating under a thicker atmosphere
have difficulty getting the required amount of heating.
But perhaps the explanation lies in the possibility that these planets
were closer to the Sun early on and that is what allowed them to have
the extensive liquid water carved features.


Bob Clark


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A report to be presented to the Fall 2004 AGU meeting will argue that
a Mars orbit closer to the Sun may partially explain how Mars was able
to remain warm enough for large scale water carved features to be
formed early in its history:

======================================
0800h
AN: P21A-0211
TI: Mars Orbit and Temperatu Why and When an Early wet Mars
AU: * Leubner, I H
EM:
AF: Rochester Institute for Fundamental Research, 35 Hillcrest Drive,
Penfield, NY 14526 United States
AB: It is the intent of this work to present a model which predicts
the time when liquid water was present on Mars. Experimental evidence
indicates that liquid water existed on the planet Mars at 2.9 - 3.4
billion years ago, when Mars was considered to be cold. A model is
presented that predicts Mars orbit and temperature variations based on
solar radiative and non-radiative (solar wind) mass losses which
affect planetary orbits. Mars orbits are predicted between 198 and 206
million Km at its formation five billion years ago vs. presently 228
million Km. The correlation between the solar (radiative) constant and
planetary orbit estimates the transition from liquid water to ice
(273K) to have occurred at about 3.4-3.8 billion years before the
present time, which is in good agreement with the experimental
estimate (2.9 - 3.4 Byr). Additional effects that are expected to
extend higher Mars surface temperatures closer to the present are
discussed. Examples are the planetary cooling rate after formation and
effects due to hothouse gases, like carbon dioxide and water vapor,
and effects dependent on variations in solar volume.

======================================

These are non-peer reviewed abstracts of course.


Bob Clark
http://uplink.space.com/showflat.php...r=6275&fpart=3

Robert Clark wrote:

[snip]
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Planetary accretion in the inner Solar System [ AlexBlackwell]

Thanks for the link. This reminds me of research on the position of
planets at their formation and where they wind up:

Moving the Orbits of Planets
http://www.ifa.hawaii.edu/faculty/je...b/migrate.html

This notes that present theories suggest some planets moved outwards
while others moved inwards.
[snop]

If Mars moved, originally being in an orbit closer to the sun, why are
the asteroids still there? Orbital resonances with Jupiter-Mars would
not have existed.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

Uncle Al wrote:

If Mars moved, originally being in an orbit closer to the sun, why are
the asteroids still there? Orbital resonances with Jupiter-Mars would
not have existed.

Din anyone calculated that Orbital resonance betwen Jupiter-Mars caused the
"missing plannet" not to aggregate ? Mars mass is so small.
I would rather suspect gravitational influence betwen Jupiter and Sun to
be the cause for the asteroid belt.
So Mars may been free to hover around without disturbing to much the site.