[meteorite-list] NASA'S Curiosity Rover Provides Clues to Changes in Martian Atmosphere

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 2 Nov 2012 23:29:37 -0700 (PDT)
Message-ID: <201211030629.qA36TbI9011003_at_zagami.jpl.nasa.gov>

Nov. 02, 2012

Dwayne Brown
Headquarters, Washington
dwayne.c.brown at nasa.gov

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

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

RELEASE: 12-387


PASADENA, Calif. -- NASA's car-sized rover, Curiosity, has taken
significant steps toward understanding how Mars may have lost much of
its original atmosphere.

Learning what happened to the Martian atmosphere will help scientists
assess whether the planet ever was habitable. The present atmosphere
of Mars is 100 times thinner than Earth's.

A set of instruments aboard the rover has ingested and analyzed
samples of the atmosphere collected near the "Rocknest" site in Gale
Crater where the rover is stopped for research. Findings from the
Sample Analysis at Mars (SAM) instruments suggest that loss of a
fraction of the atmosphere, resulting from a physical process
favoring retention of heavier isotopes of certain elements, has been
a significant factor in the evolution of the planet. Isotopes are
variants of the same element with different atomic weights.

Initial SAM results show an increase of 5 percent in heavier isotopes
of carbon in the atmospheric carbon dioxide compared to estimates of
the isotopic ratios present when Mars formed. These enriched ratios
of heavier isotopes to lighter ones suggest the top of the atmosphere
may have been lost to interplanetary space. Losses at the top of the
atmosphere would deplete lighter isotopes. Isotopes of argon also
show enrichment of the heavy isotope, matching previous estimates of
atmosphere composition derived from studies of Martian meteorites on

Scientists theorize that in Mars' distant past its environment may
have been quite different, with persistent water and a thicker
atmosphere. NASA's Mars Atmosphere and Volatile Evolution, or MAVEN,
mission will investigate possible losses from the upper atmosphere
when it arrives at Mars in 2014.

With these initial sniffs of Martian atmosphere, SAM also made the
most sensitive measurements ever to search for methane gas on Mars.
Preliminary results reveal little to no methane. Methane is of
interest as a simple precursor chemical for life. On Earth, it can be
produced by either biological or non-biological processes.

Methane has been difficult to detect from Earth or the current
generation of Mars orbiters because the gas exists on Mars only in
traces, if at all. The Tunable Laser Spectrometer (TLS) in SAM
provides the first search conducted within the Martian atmosphere for
this molecule. The initial SAM measurements place an upper limit of
just a few parts methane per billion parts of Martian atmosphere, by
volume, with enough uncertainty that the amount could be zero.

"Methane is clearly not an abundant gas at the Gale Crater site, if it
is there at all. At this point in the mission we're just excited to
be searching for it," said SAM TLS lead Chris Webster of NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, Calif. "While we determine
upper limits on low values, atmospheric variability in the Martian
atmosphere could yet hold surprises for us."

In Curiosity's first three months on Mars, SAM has analyzed atmosphere
samples with two laboratory methods. One is a mass spectrometer
investigating the full range of atmospheric gases. The other, TLS,
has focused on carbon dioxide and methane. During its two-year prime
mission, the rover also will use an instrument called a gas
chromatograph that separates and identifies gases. The instrument
also will analyze samples of soil and rock, as well as more
atmosphere samples.

"With these first atmospheric measurements we already can see the
power of having a complex chemical laboratory like SAM on the surface
of Mars," said SAM Principal Investigator Paul Mahaffy of NASA's
Goddard Space Flight Center in Greenbelt, Md. "Both atmospheric and
solid sample analyses are crucial for understanding Mars'

SAM is set to analyze its first solid sample in the coming weeks,
beginning the search for organic compounds in the rocks and soils of
Gale Crater. Analyzing water-bearing minerals and searching for and
analyzing carbonates are high priorities for upcoming SAM solid
sample analyses.

Researchers are using Curiosity's 10 instruments to investigate
whether areas in Gale Crater ever offered environmental conditions
favorable for microbial life. JPL manages the project for NASA's
Science Mission Directorate in Washington. The SAM Instrument was
developed at Goddard with instrument contributions from Goddard, JPL
and the University of Paris in France.

For more information about Curiosity and its mission, visit:


You can follow the mission on Facebook and Twitter at:



Received on Sat 03 Nov 2012 02:29:37 AM PDT

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