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NASA : Curiosity Sniffs Out History of Martian Atmosphere .- Robot Curiosity olfatea la Historia de la Atmósfera de Marte
Hola amigos: A VUELO DE UN QUINDE EL BLOG., hemos recibido información de la Agencia Espacial NASA, sobre las investigaciones del Robot Curiosity, que últimamente está olfateando sobre la historia de la atmósfera del Planeta Marte.
A Sample Analysis at Mars (SAM) team member at NASA
Goddard prepares the SAM testbed for an experiment. This test copy of the SAM
suite of instruments is inside a chamber that, when closed, can model the
pressure and temperature environment that SAM sees inside Curiosity on
NASA's Curiosity rover is using a new experiment to better understand the
history of the Martian atmosphere by analyzing xenon.
While NASA's Curiosity rover concluded its detailed examination of the rock
layers of the "Pahrump Hills" in Gale Crater on Mars this winter, some members
of the rover team were busy analyzing the Martian atmosphere for xenon, a heavy
Curiosity's Sample Analysis at Mars (SAM) experiment analyzed xenon in the
planet’s atmosphere. Since noble gases are chemically inert and do not react
with other substances in the air or on the ground, they are excellent tracers of
the history of the atmosphere. Xenon is present in the Martian atmosphere at a
challengingly low quantity and can be directly measured only with on-site
experiments such as SAM.
"Xenon is a fundamental measurement to make on a planet such as Mars or
Venus, since it provides essential information to understand the early history
of these planets and why they turned out so differently from Earth,” said
Melissa Trainer, one of the scientists analyzing the SAM data.
A planetary atmosphere is made up of different gases, which are in turn made
up of variants of the same chemical element called isotopes. When a planet loses
its atmosphere, that process can affect the ratios of remaining isotopes.
Measuring xenon tells us more about the history of the loss of the Martian
atmosphere. The special characteristics of xenon – it exists naturally in nine
different isotopes, ranging in atomic mass from 124 (with 70 neutrons per atom)
to 136 (with 82 neutrons per atom) – allows us to learn more about the process
by which the layers of atmosphere were stripped off of Mars than using
measurements of other gases.
A process removing gas from the top of the atmosphere removes lighter
isotopes more readily than heavier ones leaving a ratio higher in heavier
isotopes than it was originally.
The SAM measurement of the ratios of the nine xenon isotopes traces a very
early period in the history of Mars when a vigorous atmospheric escape process
was pulling away even the heavy xenon gas. The lighter isotopes were escaping
just a bit faster than the heavy isotopes.
Those escapes affected the ratio of isotopes in the atmosphere left behind,
and the ratios today are a signature retained in the atmosphere for billions of
years. This signature was first inferred several decades ago from isotope
measurements on small amounts of Martian atmospheric gas trapped in rocks from
Mars that made their way to Earth as meteorites.
"We are seeing a remarkably close match of the in-situ data to that from bits
of atmosphere captured in some of the Martian meteorites," said SAM Deputy
Principal Investigator Pan Conrad.
SAM previously measured the ratio of two isotopes of a different noble gas,
argon. The results pointed to continuous loss over time of much of the original
atmosphere of Mars.
The xenon experiment required months of careful testing at NASA's Goddard
Space Flight Center in Greenbelt, Maryland, using a close copy of the SAM
instrument enclosed in a chamber that simulates the Mars environment. This
testing was led by Goddard's Charles Malespin, who developed and optimized the
sequence of instructions for SAM to carry out on Mars.
"I'm gratified that we were able to successfully execute this run on Mars and
demonstrate this new capability for Curiosity," said Malespin.
NASA's Mars Science Laboratory Project is using Curiosity to determine if
life was possible on Mars and study major changes in Martian environmental
conditions. NASA studies Mars to learn more about our own planet, and in
preparation for future human missions to Mars. NASA's Jet Propulsion Laboratory
in Pasadena, California, a division of Caltech, manages the project for NASA's
Science Mission Directorate in Washington.