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

[Ron Baalke]

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   
	
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