[meteorite-list] NASA, Planetary Scientists Find Meteoritic Evidence of Mars Water Reservoir

From: Karen Ziegler <kziegler_at_meteoritecentral.com>
Date: Thu, 18 Dec 2014 23:54:06 +0000
Message-ID: <D0B8B6DD.2D7B6%kziegler_at_unm.edu>

The actual 9full) paper is online. The meteorites are:

LAR06, EETA79, Y98.

Karen





On 12/18/14 4:50 PM, "Meteorite Mailing List"
<meteorite-list at meteoritecentral.com> wrote:

>Hi Ron and List,
>
>Are these new findings based on the study of NWA 7034/pairings or Tissint
>or ?
>
>It makes mention of shergottites and Martian meteorites, but the
>abstract does not say which meteorite(s) was studied.
>
>Meteoritic evidence for a previously unrecognized hydrogen reservoir on
>Mars
>Tomohiro Usuia, b, , , Conel M. O'D. Alexanderc, Jianhua Wangc, Justin
>I. Simond, John H. Jones
>
>Abstract :
>
>Fluvial landforms on Mars suggest that it was once warm enough to
>maintain persistent liquid water on its surface. The transition to the
>present cold and dry Mars is closely linked to the history of surface
>water, yet the evolution of surficial water is poorly constrained.
>Based on in situ hydrogen isotope (D/H) analyses of quenched and
>impact glasses in Martian meteorites, we provide evidence for the
>existence of a distinct but ubiquitous water/ice reservoir (D/H=?2?3
>times Earth's ocean water) that lasted from at least the time when the
>meteorites crystallized (173?472 million years ago) to the time they
>were ejected by impacts (0.7?3.3 million years ago), but possibly much
>longer. The origin of this reservoir appears to predate the current
>Martian atmospheric water (D/H=?5?6 times Earth's ocean water) and is
>unlikely to be a simple mixture of atmospheric and primordial water
>retained in the Martian mantle (D/H ? Earth's ocean water). This
>reservoir could represent hydrated crust and/or ground ice interbedded
>within sediments. Our results corroborate the hypothesis that a buried
>cryosphere accounts for a large part of the initial water budget of
>Mars.
>
>Best regards,
>
>MikeG
>--
>-------------------------------------------------------------
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>
>
>
>On 12/18/14, Ron Baalke via Meteorite-list
><meteorite-list at meteoritecentral.com> wrote:
>>
>>
>> December 18, 2014
>>
>> NASA, Planetary Scientists Find Meteoritic Evidence of Mars Water
>>Reservoir
>>
>>
>> NASA and an international team of planetary scientists have found
>>evidence
>> in
>> meteorites on Earth that indicates Mars has a distinct and global
>>reservoir
>>
>> of water or ice near its surface.
>>
>> Though controversy still surrounds the origin, abundance and history of
>> water
>> on Mars, this discovery helps resolve the question of where the "missing
>> Martian water" may have gone. Scientists continue to study the planet's
>> historical record, trying to understand the apparent shift from an
>>early wet
>>
>> and warm climate to today's dry and cool surface conditions.
>>
>> The reservoir's existence also may be a key to understanding climate
>> history and the potential for life on Mars. The team's findings are
>> reported in the journal Earth and Planetary Science Letters.
>>
>> "There have been hints of a third planetary water reservoir in previous
>> studies of Martian meteorites, but our new data require the existence
>>of a
>> water or ice reservoir that also appears to have exchanged with a
>>diverse
>> set
>> of Martian samples," said Tomohiro Usui of Tokyo Institute of
>>Technology in
>>
>> Japan, lead author of the paper and a former NASA/Lunar and Planetary
>> Institute postdoctoral fellow. "Until this study there was no direct
>> evidence for this surface reservoir or interaction of it with rocks that
>> have
>> landed on Earth from the surface of Mars."
>>
>> Researchers from the Tokyo Institute of Technology, the Lunar and
>>Planetary
>>
>> Institute in Houston, the Carnegie Institution for Science in
>>Washington and
>>
>> NASA's Astromaterials Research and Exploration Science Division,
>>located at
>>
>> the agency's Johnson Space Center in Houston, studied three Martian
>> meteorites.
>>
>> The samples revealed water comprised of hydrogen atoms that have a
>>ratio of
>>
>> isotopes distinct from that found in water in the Red Planet's mantle
>>and
>> current atmosphere. Isotopes are atoms of the same element with
>>differing
>> numbers of neutrons.
>>
>> While recent orbiter missions have confirmed the presence of subsurface
>>ice,
>>
>> and melting ground-ice is believed to have formed some geomorphologic
>> features on Mars, this study used meteorites of different ages to show
>>that
>>
>> significant ground water-ice may have existed relatively intact over
>>time.
>>
>> Researchers emphasize that the distinct hydrogen isotopic signature of
>>the
>> water reservoir must be of sufficient size that it has not reached
>>isotopic
>>
>> equilibrium with the atmosphere.
>>
>> "The hydrogen isotopic composition of the current atmosphere could be
>>fixed
>>
>> by a quasi-steady-state process that involves rapid loss of hydrogen to
>> space
>> and the sublimation from a widespread ice layer," said coauthor John
>>Jones,
>>
>> a JSC experimental petrologist and member of NASA's Mars Curiosity rover
>> team.
>>
>> Curiosity's observations in a lakebed, in an area called Mount Sharp,
>> indicate Mars lost its water in a gradual process over a significant
>>period
>>
>> of time.
>>
>> "In the absence of returned samples from Mars, this study emphasizes the
>> importance of finding more Martian meteorites and continuing to study
>>the
>> ones we have with the ever-improving analytical techniques at our
>> disposal," said co-author Conel Alexander, a cosmochemist at the
>>Carnegie
>> Institution for Science.
>>
>> In this investigation, scientists compared water, other volatile element
>> concentrations and hydrogen isotopic compositions of glasses within the
>> meteorites, which may have formed as the rocks erupted to the surface of
>> Mars
>> in ancient volcanic activity or by impact events that hit the Martian
>> surface, knocking them off the planet.
>>
>> "We examined two possibilities, that the signature for the newly
>>identified
>>
>> hydrogen reservoir either reflects near surface ice interbedded with
>> sediment
>> or that it reflects hydrated rock near the top of the Martian crust,"
>>said
>> coauthor and JSC cosmochemist Justin Simon. "Both are possible, but the
>> fact that the measurements with higher water concentrations appear
>> uncorrelated with the concentrations of some of the other measured
>>volatile
>>
>> elements, in particular chlorine, suggests the hydrogen reservoir likely
>> existed as ice."
>>
>> The information being gathered about Mars from studies on Earth, and
>>data
>> being returned from a fleet of robotic spacecraft and rovers on and
>>around
>> the Red Planet, are paving the way for future human missions on a
>>journey to
>>
>> Mars in the 2030s.
>>
>> These findings can be viewed online in their entirety at:
>>
>> http://go.nasa.gov/1zwSjTa
>>
>> For more about the ARES Division at JSC, visit:
>>
>> http://ares.jsc.nasa.gov
>>
>> Learn about NASA's Journey to Mars at:
>>
>> http://www.nasa.gov/content/nasas-journey-to-mars/
>>
>>
>> -end-
>>
>> Dwayne Brown
>> Headquarters, Washington
>> 202-358-1726
>> dwayne.c.brown at nasa.gov
>>
>> William Jeffs
>> Johnson Space Center, Houston
>> 281-483-5111
>> william.p.jeffs at nasa.gov
>>
>> ______________________________________________
>>
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Received on Thu 18 Dec 2014 06:54:06 PM PST