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

[Ron Baalke]

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