Curiosity Detects Methane Spike on Mars
 
Dec. 16, 2014: NASA's Mars Curiosity rover has measured a tenfold spike in
methane, an organic chemical, in the atmosphere around it and detected other
organic molecules in a rock-powder sample collected by the robotic
laboratory's drill.
 
"This temporary increase in methane -- sharply up and then back down -- tells
us there must be some relatively localized source," said Sushil Atreya of the
University of Michigan, Ann Arbor, and Curiosity rover science team. "There
are many possible sources, biological or non-biological, such as interaction
of water and rock."
 
http://www.nasa.gov/jpl/msl/pia19088/
 
This image illustrates possible ways methane might be added to Mars'
atmosphere (sources) and removed from the atmosphere (sinks). NASA's Curiosity
Mars rover has detected fluctuations in methane concentration in the
atmosphere, implying both types of activity occur on modern Mars. A longer
caption discusses which are sources and which are sinks. Image Credit:
NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
 
Researchers used Curiosity's onboard Sample Analysis at Mars (SAM) laboratory
a dozen times in a 20-month period to sniff methane in the atmosphere. During
two of those months, in late 2013 and early 2014, four measurements averaged
seven parts per billion. Before and after that, readings averaged only
one-tenth that level.
 
Curiosity also detected different Martian organic chemicals in powder drilled
from a rock dubbed Cumberland, the first definitive detection of organics in
surface materials of Mars. These Martian organics could either have formed on
Mars or been delivered to Mars by meteorites.
 
Organic molecules, which contain carbon and usually hydrogen, are chemical
building blocks of life, although they can exist without the presence of life.
Curiosity's findings from analyzing samples of atmosphere and rock powder do
not reveal whether Mars has ever harbored living microbes, but the findings do
shed light on a chemically active modern Mars and on favorable conditions for
life on ancient Mars.
 
http://www.nasa.gov/jpl/msl/pia19087/#.VJCyu3tG8VQ
 
This graphic shows tenfold spiking in the abundance of methane in the Martian
atmosphere surrounding NASA's Curiosity Mars rover, as detected by a series of
measurements made with the Tunable Laser Spectrometer instrument in the
rover's Sample Analysis at Mars laboratory suite. Image Credit: 
ASA/JPL-Caltech
 
"We will keep working on the puzzles these findings present," said John
Grotzinger, Curiosity project scientist of the California Institute of
Technology in Pasadena (Caltech). "Can we learn more about the active
chemistry causing such fluctuations in the amount of methane in the
atmosphere? Can we choose rock targets where identifiable organics have been
preserved?"
 
Researchers worked many months to determine whether any of the organic
material detected in the Cumberland sample was truly Martian. Curiosity's SAM
lab detected in several samples some organic carbon compounds that were, in
fact, transported from Earth inside the rover. However, extensive testing and
analysis yielded confidence in the detection of Martian organics.
 
Identifying which specific Martian organics are in the rock is complicated by
the presence of perchlorate minerals in Martian rocks and soils. When heated
inside SAM, the perchlorates alter the structures of the organic compounds, so
the identities of the Martian organics in the rock remain uncertain.
 
"This first confirmation of organic carbon in a rock on Mars holds much
promise," said Curiosity participating scientist Roger Summons of the
Massachusetts Institute of Technology in Cambridge. "Organics are important
because they can tell us about the chemical pathways by which they were formed
and preserved. In turn, this is informative about Earth-Mars differences and
whether or not particular environments represented by Gale Crater sedimentary
rocks were more or less favorable for accumulation of organic materials. The
challenge now is to find other rocks on Mount Sharp that might have different
and more extensive inventories of organic compounds."
 
Researchers also reported that Curiosity's taste of Martian water, bound into
lakebed minerals in the Cumberland rock more than three billion years ago,
indicates the planet lost much of its water before that lakebed formed and
continued to lose large amounts after.
 
SAM analyzed hydrogen isotopes from water molecules that had been locked
inside a rock sample for billions of years and were freed when SAM heated it,
yielding information about the history of Martian water. The ratio of a
heavier hydrogen isotope, deuterium, to the most common hydrogen isotope can
provide a signature for comparison across different stages of a planet's
history.
 
"It's really interesting that our measurements from Curiosity of gases
extracted from ancient rocks can tell us about loss of water from Mars," said
Paul Mahaffy, SAM principal investigator of NASA's Goddard Space Flight Center
in Greenbelt, Maryland, and lead author of a report published online this week
by the journal Science
 
The ratio of deuterium to hydrogen has changed because the lighter hydrogen
escapes from the upper atmosphere of Mars much more readily than heavier
deuterium. In order to go back in time and see how the deuterium-to-hydrogen
ratio in Martian water changed over time, researchers can look at the ratio in
water in the current atmosphere and water trapped in rocks at different times
in the planet's history.
 
Martian meteorites found on Earth also provide some information, but this
record has gaps. No known Martian meteorites are even close to the same age as
the rock studied on Mars, which formed about 3.9 billion to 4.6 billion years
ago, according to Curiosity's measurements.
 
The ratio that Curiosity found in the Cumberland sample is about one-half the
ratio in water vapor in today's Martian atmosphere, suggesting much of the
planet's water loss occurred since that rock formed. However, the measured
ratio is about three times higher than the ratio in the original water supply
of Mars, based on assumption that supply had a ratio similar to that measured
in Earth's oceans. This suggests much of Mars' original water was lost before
the rock formed.
 
Credits and more information:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
 
Curiosity is one element of NASA's ongoing Mars research and preparation for a
human mission to Mars in the 2030s. Caltech manages the Jet Propulsion
Laboratory in Pasadena, California, and JPL manages Curiosity rover science
investigations for NASA's Science Mission Directorate in Washington. The SAM
investigation is led by Paul Mahaffy of Goddard. Two of SAM instruments key in
these discoveries are the Quadrupole Mass Spectrometer, developed at Goddard,
and the Tunable Laser Spectrometer, developed at JPL.
 
The results of the Curiosity rover investigation into methane detection and
the Martian organics in an ancient rock were discussed at a news briefing
Tuesday at the American Geophysical Union's convention in San Francisco. The
methane results are described in a paper published online this week in the
journal Science by NASA scientist Chris Webster of JPL, and co-authors.
 
A report on organics detection in the Cumberland rock by NASA scientist
Caroline Freissenet, of Goddard, and co-authors, is pending publication.
 
For copies of the new Science papers about Mars methane and water,
visit:http://go.nasa.gov/1cbk35X
 
For more information about Curiosity, visit http://www.nasa.gov/msl and
http://mars.jpl.nasa.gov/msl/
 
Learn about NASA's Journey to Mars at http://www.nasa.gov/conten
/nasas-journey-to-mars/
 
 
Regards,
 
Roger

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