This picture shows a lab demonstration of the measurement chamber inside the Tunable Laser Spectrometer, an instrument that is part of the Sample Analysis at Mars investigation on NASA's Curiosity rover.
Image Credit:
NASA/JPL-Caltech
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› Full SizeShooting Lasers
This picture shows a lab demonstration of the measurement chamber inside the Tunable Laser Spectrometer, an instrument that is part of the Sample Analysis at Mars investigation on NASA's Curiosity rover. This demonstration uses visible lasers – rather than the infrared ones on the actual spectrometer – to show how the lasers bounce between the mirrors in the measurement chamber.The TLS shoots laser beams into a type of measurement chamber that can be filled with Mars air. By measuring the absorption of light at specific wavelengths, the tool can measure concentrations of methane, carbon dioxide and water vapor in the Martian atmosphere and different isotopes of those gases.
Image credit: NASA/JPL-Caltech
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› Full SizeThe Five Most Abundant Gases in the Martian Atmosphere
This graph shows the percentage abundance of five gases in the atmosphere of Mars, as measured by the Quadrupole Mass Spectrometer instrument of the Sample Analysis at Mars instrument suite on NASA's Mars rover in October 2012. The season was early spring in Mars' southern hemisphere, and the location was inside Mars' Gale Crater, at 4.49 degrees south latitude, 137.42 degrees east longitude.The graph uses as logarithmic scale for volume percentage of the atmosphere so that these gases with very different concentrations can all be plotted. By far the predominant gas is carbon dioxide, making up 95.9 percent of the atmosphere's volume. The next four most abundant gases are argon, nitrogen, oxygen and carbon monoxide. Researchers will use SAM repeatedly throughout Curiosity's mission on Mars to check for seasonal changes in atmospheric composition.
Image Credit: NASA/JPL-Caltech, SAM/GSFC
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 five 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
Earth.
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 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' habitability."
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, a division of the California Institute of
Technology in Pasadena, manages the project for NASA's Science Mission
Directorate, Washington, and built Curiosity. 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: http://www.nasa.gov/msl
You can follow the mission on Facebook and Twitter
Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov
Nancy Neal Jones 301-286-0039
NASA Goddard Space Flight Center, Greenbelt, Md.
nancy.n.jones@nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov
Nancy Neal Jones 301-286-0039
NASA Goddard Space Flight Center, Greenbelt, Md.
nancy.n.jones@nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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