[meteorite-list] New Theory Explains Reactivity of Martian Soil

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sat Aug 5 01:28:44 2006
Message-ID: <007201c6b84f$fa6c0c30$6d5ce146_at_ATARIENGINE>

Hi,

    Add an electric field sensor to the next Mars Rover...

http://www.sciencedaily.com/releases/2006/08/060802101454.htm

Scientists Suggest Solution To 30-Year-Old Martian Mystery

    Electricity generated in dust storms on Mars may produce reactive
chemicals that build up in the Martian soil, according to NASA-funded
research. The chemicals, like hydrogen peroxide (H2O2), may have caused the
contradictory results when NASA's Viking landers tested the Martian soil for
signs of life, according to the researchers.
    Lead authors Gregory Delory, senior fellow at the University of
California Berkeley Space Sciences Laboratory, and Sushil Atreya, planetary
science professor at the University of Michigan, Ann Arbor, reported their
results in a tandem set of papers in the June 2006 issue of the journal
"Astrobiology".
    Dust particles become electrified in Martian dust storms when they rub
against each other as they are carried by the winds, transferring positive
and negative electric charge in the same way you build up static electricity
if you shuffle across a carpet. "From our field work, we know that strong
electric fields are generated by dust storms on Earth," said co-author
William Farrell of NASA's Goddard Space Flight Center, Greenbelt, Md. "Also,
laboratory experiments and theoretical studies indicate that conditions in
the Martian atmosphere should produce strong electric fields during dust
storms there as well."
    Delory's team calculated that electric fields generated by the swirling
dust are strong enough to break apart carbon dioxide and water molecules in
the Martian atmosphere. "Our calculations indicate that once these electric
fields are produced by dust storms on Mars, they free more electrons from
atoms and molecules in the thin Martian atmosphere. These electrons then
collide with and break apart molecules such as water and carbon dioxide,
creating new chemical products that continue to react with other
constituents in Mars' atmosphere," said Delory.
    Atreya's team then identified the various ways the broken molecules
recombine into reactive chemicals like hydrogen peroxide and ozone (O3), and
calculated the amounts that might accumulate in the Martian soil over time.
"Once carbon dioxide and water are broken apart, the resulting products
interact with the other molecules in the Martian atmosphere to produce large
quantities of the highly-reactive hydrogen peroxide. In fact hydrogen
peroxide produced by dust electrification can greatly exceed the rate that
it is produced by the conventional energy source of ultraviolet radiation
from the sun, so much so that hydrogen peroxide would snow out of the
atmosphere and permeate the Martian soil," said Atreya.
    In 1976, the twin Viking landers scooped up Martian soil and added
nutrients mixed with water to it. If microscopic life were present, the
nutrients would be used up and waste products would be released. Three
different experiments involved in this test gave conflicting results. The
Labeled Release and the Gas Exchange experiments indicated something active
was in the soil, because the nutrients were broken down. However, the Mass
Spectrometer experiment did not find any organic matter in the soil.
    In 1977, Viking researchers suggested that the apparent contradiction
could be explained if a very reactive nonorganic substance that imitated the
activity of life by breaking down the nutrients was embedded in the soil.
Hydrogen peroxide and ozone were considered possible candidate reactive
compounds. While ultraviolet radiation from the sun could produce a certain
amount of reactive chemicals in the atmosphere, there were no physical
processes known to explain how large amounts of such reactive material could
accumulate in the Martian soil. Some researchers at the time considered the
possibility that dust storms might be electrically active in a way similar
to terrestrial thunderstorms, and that these storms might be a source of the
new reactive chemistry.
    This dust storm suggestion remained dormant for close to 30 years. The
Astrobiology papers now provide detailed analysis to support this theory,
based on results from field and laboratory studies by the team over the past
five years. The theory could be tested further by an electric field sensor
working in tandem with an atmospheric chemistry system on a future Mars
rover or lander, according to the teams.
    The team includes Delory, Atreya, Farrell, and Nilton Renno & Ah-San
Wong, (University of Michigan), Steven Cummer (Duke University, Durham,
N.C.), Davis Sentman (University of Alaska), John Marshall (SETI Inst.,
Mountain View, Calif.), Scot Rafkin (Southwest Research Institute, San
Antonio, Texas) and David Catling (University of Washington). The research
was funded by NASA's Mars Fundamental Research Program and NASA Goddard
internal institutional funds.
Received on Sat 05 Aug 2006 01:28:26 AM PDT