[meteorite-list] NASA Curiosity Rover Finds Active and Ancient Organic Chemistry on Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 16 Dec 2014 11:26:37 -0800 (PST)
Message-ID: <201412161926.sBGJQbke023496_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4413

NASA Rover Finds Active and Ancient Organic Chemistry on Mars
Jet Propulsion Laboratory
December 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, a member of the Curiosity
rover science team. "There are many possible sources, biological or non-biological,
such as interaction of water and rock."

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.

"We will keep working on the puzzles these findings present," said John
Grotzinger, Curiosity project scientist of the California Institute of
Technology in Pasadena. "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 the 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.

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 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/


Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

Nancy Neal Jones
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039
nancy.n.jones at nasa.gov

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

2014-432
Received on Tue 16 Dec 2014 02:26:37 PM PST