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: NASA/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{at}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/content/nasas-journey-to-mars/
 
 
Regards,
 
Roger

--- D'Bridge 3.99