[meteorite-list] Remaining Martian Atmosphere Still Dynamic (MSL)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 8 Apr 2013 08:58:09 -0700 (PDT)
Message-ID: <201304081558.r38Fw9FR005476_at_zagami.jpl.nasa.gov>

Remaining Martian Atmosphere Still Dynamic
Jet Propulsion Laboratory
April 8, 2013

    * This image shows the first holes into rock drilled by NASA's Mars
      rover Curiosity <#1>
    * This illustration shows the instruments and subsystems of the
      Sample Analysis at Mars (SAM) suite on the Curiosity Rover of
      NASA's Mars Science Laboratory Project <#2>
    * the Sample Analysis at Mars (SAM) suite of instruments on NASA's
      Curiosity Mars rover <#3>
    * This image shows the ratio of the argon isotope argon-36 to the
      heavier argon isotope argon-38, in various measurements. <#4>
    * This pair of images taken a few minutes apart show how laser
      firing by NASA's Mars rover Curiosity removes dust from the
      surface of a rock. <#5>
    * The Chemistry and Camera (ChemCam) instrument on NASA's Curiosity
      Mars rover <#6>
    * The Chemistry and Camera (ChemCam) instrument on NASA's Curiosity
      Mars rover analyzes Martian rocks, soils and dust at scales of
      less than 0.04 inch (1 millimeter) <#7>
    * This graph shows about one-fourth of a Martian year's pattern
      atmospheric pressure at the surface of Mars, as measured by the
      Rover Environmental Monitoring Station on NASA's Curiosity rover <#8>
    * This pair of graphs shows about one-fourth of a Martian year's
      record of temperatures (in degrees Celsius) measured by the Rover
      Environmental Monitoring Station (REMS) on NASA's Curiosity rover
      <#9>
    * NASA's Curiosity Mars rover has detected dozens of whirlwinds, or
      vortex events <#10>
    * This graphic tracks the maximum relative humidity and the
      temperature at which that maximum occurred each Martian day for
      about one-fourth of a Martian year, as measured by NASA's
      Curiosity Mars rover <#11>
    * This diagram and the one at PIA16917 illustrate how the Dynamic
      Albedo of Neutrons (DAN) instrument on NASA's Curiosity Mars rover
      detects hydrogen in the ground beneath the rover <#12>
    * This diagram and the one at PIA16916 illustrate how the Dynamic
      Albedo of Neutrons (DAN) instrument on NASA's Curiosity Mars rover
      detects hydrogen in the ground beneath the rover <#13>

VIENNA -- Mars has lost much of its original atmosphere, but what's left
remains quite active, recent findings from NASA's Mars rover Curiosity
indicate. Rover team members reported diverse findings today at the
European Geosciences Union 2013 General Assembly, in Vienna.

Evidence has strengthened this month that Mars lost much of its original
atmosphere by a process of gas escaping from the top of the atmosphere.

Curiosity's Sample Analysis at Mars (SAM) instrument analyzed an
atmosphere sample last week using a process that concentrates selected
gases. The results provided the most precise measurements ever made of
isotopes of argon in the Martian atmosphere. Isotopes are variants of
the same element with different atomic weights. "We found arguably the
clearest and most robust signature of atmospheric loss on Mars," said
Sushil Atreya, a SAM co-investigator at the University of Michigan, Ann
Arbor.

SAM found that the Martian atmosphere has about four times as much of a
lighter stable isotope (argon-36) compared to a heavier one (argon-38).
This removes previous uncertainty about the ratio in the Martian
atmosphere from 1976 measurements from NASA's Viking project and from
small volumes of argon extracted from Martian meteorites. The ratio is
much lower than the solar system's original ratio, as estimated from
argon-isotope measurements of the sun and Jupiter. This points to a
process at Mars that favored preferential loss of the lighter isotope
over the heavier one.

Curiosity measures several variables in today's Martian atmosphere with
the Rover Environmental Monitoring Station (REMS), provided by Spain.
While daily air temperature has climbed steadily since the measurements
began eight months ago and is not strongly tied to the rover's location,
humidity has differed significantly at different places along the
rover's route. These are the first systematic measurements of humidity
on Mars.

Trails of dust devils have not been seen inside Gale Crater, but REMS
sensors detected many whirlwind patterns during the first hundred
Martian days of the mission, though not as many as detected in the same
length of time by earlier missions. "A whirlwind is a very quick event
that happens in a few seconds and should be verified by a combination of
pressure, temperature and wind oscillations and, in some cases, a
decrease is ultraviolet radiation," said REMS Principal Investigator
Javier G??mez-Elvira of the Centro de Astrobiolog??a, Madrid.

Dust distributed by the wind has been examined by Curiosity's
laser-firing Chemistry and Camera (ChemCam) instrument. Initial laser
pulses on each target hit dust. The laser's energy removes the dust to
expose underlying material, but those initial pulses also provide
information about the dust.

"We knew that Mars is red because of iron oxides in the dust," said
ChemCam Deputy Principal Investigator Sylvestre Maurice of the Institut
de Recherche en Astrophysique et Plan??tologie in Toulouse, France.
"ChemCam reveals a complex chemical composition of the dust that
includes hydrogen, which could be in the form of hydroxyl groups or
water molecules."

Possible interchange of water molecules between the atmosphere and the
ground is studied by a combination of instruments on the rover,
including the Dynamic Albedo of Neutrons (DAN), provided by Russia under
the leadership of DAN Principal Investigator Igor Mitrofanov.

For the rest of April, Curiosity will carry out daily activities for
which commands were sent in March, using DAN, REMS and the Radiation
Assessment Detector (RAD). No new commands are being sent during a
four-week period while Mars is passing nearly behind the sun, from
Earth's perspective. This geometry occurs about every 26 months and is
called Mars solar conjunction.

"After conjunction, Curiosity will be drilling into another rock where
the rover is now, but that target has not yet been selected. The science
team will discuss this over the conjunction period." said Mars Science
Laboratory Project Scientist John Grotzinger, of the California
Institute of Technology, Pasadena.

NASA's Mars Science Laboratory Project is using Curiosity to investigate
the environmental history within Gale Crater, a location where the
project has found that conditions were long ago favorable for microbial
life. Curiosity, carrying 10 science instruments, landed in August 2012
to begin its two-year prime mission. NASA's Jet Propulsion Laboratory, a
division of Caltech in Pasadena, manages the project for NASA's Science
Mission Directorate in Washington.

For more about the mission, visit: http://www.jpl.nasa.gov/msl ,
http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl . You can
follow the mission on Facebook and Twitter at:
http://www.facebook.com/marscuriosity and
http://www.twitter.com/marscuriosity .

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

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Received on Mon 08 Apr 2013 11:58:09 AM PDT