[meteorite-list] NASA Curiosity Rover Detects No Methane on Mars

[Ron Baalke]

September 19, 2013

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

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov 
     
RELEASE 13-288
     
NASA Curiosity Rover Detects No Methane on Mars

Data from NASA's Curiosity rover has revealed the Martian environment lacks  
methane. This is a surprise to researchers because previous data reported by  
U.S. and international scientists indicated positive detections.

The roving laboratory performed extensive tests to search for traces of  
Martian methane. Whether the Martian atmosphere contains traces of the gas  
has been a question of high interest for years because methane could be a  
potential sign of life, although it also can be produced without biology.

"This important result will help direct our efforts to examine the  
possibility of life on Mars," said Michael Meyer, NASA's lead scientist for  
Mars exploration. "It reduces the probability of current methane-producing  
Martian microbes, but this addresses only one type of microbial metabolism.  
As we know, there are many types of terrestrial microbes that don't generate  
methane."

Curiosity analyzed samples of the Martian atmosphere for methane six times  
from October 2012 through June and detected none. Given the sensitivity of  
the instrument used, the Tunable Laser Spectrometer, and not detecting the  
gas, scientists calculate the amount of methane in the Martian atmosphere  
today must be no more than 1.3 parts per billion, which is about one-sixth as  
much as some earlier estimates. Details of the findings appear in the  
Thursday edition of Science Express.

"It would have been exciting to find methane, but we have high confidence in  
our measurements, and the progress in expanding knowledge is what's really  
important," said the report's lead author, Chris Webster of NASA's Jet  
Propulsion Laboratory in Pasadena, Calif. "We measured repeatedly from  
Martian spring to late summer, but with no detection of methane."

Webster is the lead scientist for spectrometer, which is part of Curiosity's  
Sample Analysis at Mars (SAM) laboratory. It can be tuned specifically for  
detection of trace methane. The laboratory also can concentrate any methane  
to increase the gas' ability to be detected. The rover team will use this  
method to check for methane at concentrations well below 1 part per billion.

Methane, the most abundant hydrocarbon in our solar system, has one carbon  
atom bound to four hydrogen atoms in each molecule. Previous reports of  
localized methane concentrations up to 45 parts per billion on Mars, which  
sparked interest in the possibility of a biological source on Mars, were  
based on observations from Earth and from orbit around Mars. However, the  
measurements from Curiosity are not consistent with such concentrations, even  
if the methane had dispersed globally.

"There's no known way for methane to disappear quickly from the atmosphere,"  
said one of the paper's co-authors, Sushil Atreya of the University of  
Michigan. "Methane is persistent. It would last for hundreds of years in the  
Martian atmosphere. Without a way to take it out of the atmosphere quicker,  
our measurements indicate there cannot be much methane being put into the  
atmosphere by any mechanism, whether biology, geology, or by ultraviolet  
degradation of organics delivered by the fall of meteorites or interplanetary  
dust particles."

The highest concentration of methane that could be present without being  
detected by Curiosity's measurements so far would amount to no more than 10  
to 20 tons per year of methane entering the Martian atmosphere, Atreya  
estimated. That is about 50 million times less than the rate of methane  
entering Earth's atmosphere.

Curiosity landed inside Gale Crater on Mars in August 2012 and is  
investigating evidence about habitable environments there. JPL manages the  
mission and built the rover for NASA's Science Mission Directorate in  
Washington. The rover's Sample Analysis at Mars suite of instruments was  
developed at NASA's Goddard Space Flight Center in Greenbelt, Md., with  
instrument contributions from Goddard, JPL and the University of Paris in  
France.

For more information about the mission, visit:

http://www.nasa.gov/msl 

and

http://mars.jpl.nasa.gov/msl

To learn more about the SAM instrument, visit:

http://ssed.gsfc.nasa.gov/sam/index.html 

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