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Posted by BradGuth on September 16, 2007, 9:06 pm
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On Sep 14, 5:17 pm, baa...@earthlink.net wrote:
> Embargoed until 1 p.m. Eastern Time (7 a.m. HST), September 12, 2007
>
> Contacts:
>
> Dr. Norbert Schorghofer
> Institute for Astronomy
> University of Hawaii at Manoa
> Honolulu, Hawaii 96822
> 1-808-956-9086
> no...@ifa.hawaii.edu
>
> Mrs. Karen Rehbock
> Assistant to the Director
> Institute for Astronomy
> University of Hawaii at Manoa
> 1-808-956-6829
> rehb...@ifa.hawaii.edu
>
> Electronic
version:http://www.ifa.hawaii.edu/info/press-releases/Norbert-9-07/IceAgesOnM...
>
> New Theory Explains Ice on Mars
>
> Wobbles on Mars cause ice ages that are much more
> dramatic than those on Earth, says astronomer
> Norbert Schorghofer of the University of Hawaii.
>
> Thanks to our large, stabilizing Moon, Earth's
> rotation axis is always tilted by about 23
> degrees. The tilt of Mars, however, can wobble by
> as much as10 degrees from its current 25 degrees.
> Wobbles cause big changes in the amount of
> sunlight reaching different parts of Mars, so
> vast amounts of ice shift between the poles and
> the rest of the planet every 120,000 years.
>
> Schorghofer's new theory appears in the September
> 13 issue of the journal Nature.
>
> "We expect to see two types of ground ice when
> the Phoenix Lander spacecraft arrives at Mars in
> 2008," says Schorghofer, "ice that formed on the
> surface and was then buried, and ice hidden in
> porous soil."
>
> During the 19th century, scientists discovered
> that Earth experienced ice ages. In the past few
> years, spacecraft have discovered that ice ages
> also occurred on Mars, but scientists have been
> puzzled because more ice than expected has
> survived far from the polar caps. What is left is
> now thought to be a combination of old ice from
> the last major glaciation and younger ice that
> formed later and in a way entirely different from
> the way ice formed on Earth.
>
> The new theory sheds light on the history of vast
> ice-rich areas, which once covered most of Mars.
> Around 4 to 5 million years ago, ice accumulated
> from extensive snowfall outside the martian polar
> caps. The new theory describes what happened to
> this ice as the rotation axis of Mars continued
> to wobble over the last few million years.
>
> Surface temperature and atmospheric humidity
> changed because of varying sunlight. When the
> climate was dry, the ice receded to a greater
> depth or disappeared entirely except at the
> highest latitudes. Dust contained in retreating
> ice eventually covered the ice, making it no
> longer visible on the surface.
>
> So much of this subsurface ice has been detected
> that its only plausible origin was thought to be
> massive snowfall. However, Schorghofer's theory
> suggests that a lot of that snowfall ice has
> since been lost to the atmosphere. It has been
> replaced by a new layer of ice, formed not from
> snowfall, since the climate had meanwhile turned
> less humid, but by diffusion of water vapor into
> the soil. Atmospheric vapor can freeze inside the
> soil and form "pore-ice," which is mainly soil
> with some ice in pore spaces.
>
> As the planet's tilt toward the sun went back and
> forth, the climate kept changing between dry and
> humid, causing many cycles of ice retreat and
> formation. Today we are left with two kinds of
> ground ice: the old massive ice sheet and very
> recent pore-ice.
>
> Schorghofer is part of the multidisciplinary UH
> Astrobiology Institute, which is sponsored by
> NASA and managed through the Institute for
> Astronomy. Its research focuses on water as the
> habitat of, and chemical enabler for, life.
>
> Figure captions:
>
> Figure 1. The two types of ice found on Mars, by
> latitude. Dry soil covers both types of ice.
>
> Figure 2. The history of subsurface ice layers on
> Mars over the last few million years. The tilt of
> the rotation axis changes with time, and the
> planet periodically experiences dry and humid
> climates.
>
> The NASA Astrobiology Institute (NAI), founded in
> 1998, is a partnership between NASA, 16 major
> U.S. teams, and five international consortia.
> NAI's goal is to promote, conduct, and lead
> integrated multidisciplinary astrobiology
> research and to train a new generation of
> astrobiology researchers. For more information,
> seehttp://nai.nasa.gov/.
>
> The Institute for Astronomy at the University of
> Hawaii at Manoa conducts research into galaxies,
> cosmology, stars, planets, and the sun. Its
> faculty and staff are also involved in astronomy
> education, deep space missions, and in the
> development and management of the observatories
> on Haleakala and Mauna Kea.
>
> Established in 1907 and fully accredited by the
> Western Association of Schools and Colleges, the
> University of Hawaii is the state's sole public
> system of higher education. The UH System
> provides an array of undergraduate, graduate, and
> professional degrees and community programs on 10
> campuses and through educational, training, and
> research centers across the state. UH enrolls
> more than 50,000 students from Hawaii, the U.S.
> mainland, and around the world.
>
> ###
A better theory; Mars no longer has any significant cache of fresh
water ice, and there's hardly any remains of salt. Go figure.
- Brad Guth -
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