[meteorite-list] Discovery of Methane Reveals Mars Is Not a Dead Planet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sat, 17 Jan 2009 15:25:13 -0800 (PST)
Message-ID: <200901172325.PAA09012_at_zagami.jpl.nasa.gov>

Jan. 15, 2009

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Nancy Neal-Jones/Bill Steigerwald
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039/5017
nancy.n.jones at nasa.gov, william.a.steigerwald at nasa.gov

RELEASE: 09-006

DISCOVERY OF METHANE REVEALS MARS IS NOT A DEAD PLANET

WASHINGTON -- A team of NASA and university scientists has achieved
the first definitive detection of methane in the atmosphere of Mars.
This discovery indicates the planet is either biologically or
geologically active.

The team found methane in the Martian atmosphere by carefully
observing the planet throughout several Mars years with NASA's
Infrared Telescope Facility and the W.M. Keck telescope, both at
Mauna Kea, Hawaii. The team used spectrometers on the telescopes to
spread the light into its component colors, as a prism separates
white light into a rainbow. The team detected three spectral features
called absorption lines that together are a definitive signature of
methane.

"Methane is quickly destroyed in the Martian atmosphere in a variety
of ways, so our discovery of substantial plumes of methane in the
northern hemisphere of Mars in 2003 indicates some ongoing process is
releasing the gas," said Michael Mumma of NASA's Goddard Space Flight
Center in Greenbelt, Md. "At northern mid-summer, methane is released
at a rate comparable to that of the massive hydrocarbon seep at Coal
Oil Point in Santa Barbara, Calif." Mumma is lead author of a paper
describing this research that will appear in Science Express on
Thursday.

Methane, four atoms of hydrogen bound to a carbon atom, is the main
component of natural gas on Earth. Astrobiologists are interested in
these data because organisms release much of Earth's methane as they
digest nutrients. However, other purely geological processes, like
oxidation of iron, also release methane.

"Right now, we do not have enough information to tell whether biology
or geology -- or both -- is producing the methane on Mars," Mumma
said. "But it does tell us the planet is still alive, at least in a
geologic sense. It is as if Mars is challenging us, saying, 'hey,
find out what this means.' "

If microscopic Martian life is producing the methane, it likely
resides far below the surface where it is warm enough for liquid
water to exist. Liquid water is necessary for all known forms of
life, as are energy sources and a supply of carbon.

"On Earth, microorganisms thrive about 1.2 to 1.9 miles beneath the
Witwatersrand basin of South Africa, where natural radioactivity
splits water molecules into molecular hydrogen and oxygen," Mumma
said. "The organisms use the hydrogen for energy. It might be
possible for similar organisms to survive for billions of years below
the permafrost layer on Mars, where water is liquid, radiation
supplies energy, and carbon dioxide provides carbon. Gases, like
methane, accumulated in such underground zones might be released into
the atmosphere if pores or fissures open during the warm seasons,
connecting the deep zones to the atmosphere at crater walls or
canyons."

It is possible a geologic process produced the Martian methane, either
now or eons ago. On Earth, the conversion of iron oxide into the
serpentine group of minerals creates methane, and on Mars this
process could proceed using water, carbon dioxide and the planet's
internal heat. Although there is no evidence of active volcanism on
Mars today, ancient methane trapped in ice cages called clathrates
might be released now.

"We observed and mapped multiple plumes of methane on Mars, one of
which released about 19,000 metric tons of methane," said co-author
Geronimo Villanueva of the Catholic University of America in
Washington. "The plumes were emitted during the warmer seasons,
spring and summer, perhaps because ice blocking cracks and fissures
vaporized, allowing methane to seep into the Martian air."

According to the team, the plumes were seen over areas that show
evidence of ancient ground ice or flowing water. Plumes appeared over
the Martian northern hemisphere regions such as east of Arabia Terra,
the Nili Fossae region, and the south-east quadrant of Syrtis Major,
an ancient volcano about 745 miles across.

One method to test whether life produced this methane is by measuring
isotope ratios. Isotopes of an element have slightly different
chemical properties, and life prefers to use the lighter isotopes. A
chemical called deuterium is a heavier version of hydrogen. Methane
and water released on Mars should show distinctive ratios for
isotopes of hydrogen and carbon if life was responsible for methane
production. It will take future missions, like NASA's Mars Science
Laboratory, to discover the origin of the Martian methane.

The research was funded by the Planetary Astronomy Program at NASA
Headquarters in Washington and the Astrobiology Institute at NASA's
Ames Research Center in Moffett Field, Calif. The University of
Hawaii manages NASA's Infrared Telescope Facility.

For images related to this finding, visit:

http://www.nasa.gov/mars
        
-end-
Received on Sat 17 Jan 2009 06:25:13 PM PST