Hola amigos: A VUELO DE UN QUINDE EL BLOG.,la Agencia Espacial NASA, nos revela sobre los efectos que produjo sobre la atmósfera de Marte el sobrevuelo del Cometa : Comet C/2013 A1 Siding Spring, la agencia utilizó dos satélites: NASA's Mars Atmosphere and Volatile Evolution (MAVEN) misión, y NASA’s Mars Reconnaissance Orbiter (MRO), con el apoyo de la Agencia: European Space Agency (ESA) con su nave: Mars Express spacecraft.
El cometa pasó tan cerca de Marte, que NASA nos informa así: "El cometa C / 2013 A1 Siding Spring viajó desde la región más distante de nuestro sistema solar, llamada la Nube de Oort, e hizo un acercamiento cercano alrededor de 14:27 EDT dentro de aproximadamente 87.000 millas (139.500 kilometros) del planeta rojo. Esto es menos de la mitad de la distancia entre la Tierra y la Luna, y menos de una décima parte de la distancia de cualquier sobrevuelo del cometa conocido de la Tierra...
Artist’s concept of Comet Siding Spring approaching
Mars, shown with NASA’s orbiters preparing to make science observations of this
unique encounter.
Image Credit:
NASA/JPL
This movie begins with an animation (artist's
rendering) of NASA's Mars Reconnaissance Orbiter spacecraft above Mars. The
scene zooms into an "X-ray" view of the spacecraft, revealing the High
Resolution Imaging Science Experiment (HiRISE) camera.
Five images of comet Siding Spring taken within a
35-minute period as it passed near Mars on Oct. 19, 2014, provide information
about the size of the comet's nucleus. The images were acquired by the High
Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars
Reconnaissance Orbiter.
Image Credit:
NASA/JPL-Caltech/University of
Arizona
Feature Link:
These spectrograms from the MARSIS instrument on
the European Space Agency's Mars Express orbiter show the intensity of radar
echo in Mars' far-northern ionosphere at three times on Oct. 19 and 20, 2014.
The middle plot reveals effects attributed to dust from a comet that passed near
Mars that day.
Image Credit:
ASI/NASA/ESA/JPL/Univ. of Rome/Univ. of
Iowa
Feature Link:
Two NASA and one European
spacecraft that obtained the first up-close observations of a comet flyby of
Mars on Oct. 19, have gathered new information about the basic properties of the
comet’s nucleus and directly detected the effects on the Martian atmosphere.
Data from observations carried out by NASA's Mars Atmosphere and Volatile
Evolution (MAVEN) mission, NASA’s Mars Reconnaissance Orbiter (MRO), and a radar
instrument on the European Space Agency's (ESA’s) Mars Express spacecraft have
revealed that debris from the comet added a temporary and very strong layer of
ions to the ionosphere, the electrically charged layer high above Mars. In these
observations, scientists were able to make a direct connection from the input of
debris from a specific meteor shower to the formation of this kind of transient
layer in response; that is a first on any planet, including Earth.
Comet C/2013 A1 Siding Spring traveled from the most distant region of our
solar system, called the Oort Cloud, and made a close approach around 2:27 p.m.
EDT within about 87,000 miles (139,500 kilometers) of the Red Planet. This is
less than half the distance between Earth and our moon and less than one-tenth
the distance of any known comet flyby of Earth.
Dust from the comet impacted Mars and was vaporized high in the atmosphere,
producing what was likely an impressive meteor shower. This debris resulted in
significant temporary changes to the planet’s upper atmosphere and possible
longer-term perturbations. Earth-based and a host of space telescopes also
observed the unique celestial object.
“This historic event allowed us to observe the details of this fast-moving
Oort Cloud comet in a way never before possible using our existing Mars
missions,” said Jim Green, director of NASA’s Planetary Science Division at the
agency’s Headquarters in Washington. “Observing the effects on Mars of the
comet's dust slamming into the upper atmosphere makes me very happy that we
decided to put our spacecraft on the other side of Mars at the peak of the dust
tail passage and out of harm's way.”
The MAVEN spacecraft, recently arrived at Mars, detected the comet encounter
in two ways. The remote-sensing Imaging Ultraviolet Spectrograph observed
intense ultraviolet emission from magnesium and iron ions high in the atmosphere
in the aftermath of the meteor shower. Not even the most intense meteor storms
on Earth have produced as strong a response as this one. The emission dominated
Mars' ultraviolet spectrum for several hours after the encounter and
then dissipated over the next two days.
MAVEN also was able to directly sample and determine the composition of some
of the comet dust in Mars’ atmosphere. Analysis of these samples by the
spacecraft’s Neutral Gas and Ion Mass Spectrometer detected eight different
types of metal ions, including sodium, magnesium and iron. These are the first
direct measurements of the composition of dust from an Oort Cloud comet. The
Oort Cloud, well beyond the outer-most planets that surround our sun, is a
spherical region of icy objects believed to be material left over from the
formation of the solar system.
Elsewhere above Mars, a joint U.S. and Italian instrument on Mars Express
observed a huge increase in the density of electrons following the comet's close
approach. This instrument, the Mars Advanced Radar for Subsurface and
Ionospheric Sounding (MARSIS), saw a huge jump in the electron density in the
ionosphere a few hours after the comet rendezvous. This spike occurred at a
substantially lower altitude than the normal density peak in the Martian
ionosphere. The increased ionization, like the effects observed by MAVEN,
appears to be the result of fine particles from the comet burning up in the
atmosphere.
MRO’s Shallow Subsurface Radar (SHARAD) also detected the enhanced
ionosphere. Images from the instrument were smeared by the passage of the radar
signals through the temporary ion layer created by the comet's dust. SHARAD
scientists used this smearing to determine that the electron density of the
ionosphere on the planet's night side, where the observations were made, was
five to 10 times higher than usual.
Studies of the comet itself, made with MRO's High Resolution Imaging Science
Experiment (HiRISE) camera, revealed the nucleus is smaller than the expected
1.2 miles (2 kilometers). The HiRISE images also indicate a rotation period for
the nucleus of eight hours, which is consistent with recent preliminary
observations by NASA’s Hubble Space Telescope.
MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) also
observed the comet to see whether signs of any particular chemical constituents
stood out in its spectrum. Team members said the spectrum appears to show a
dusty comet with no strong emission lines at their instrument’s sensitivity.
In addition to these immediate effects, MAVEN and the other missions will
continue to look for long-term perturbations to Mars’ atmosphere.
MAVEN's principal investigator is based at the University of Colorado's
Laboratory for Atmospheric and Space Physics in Boulder, and NASA's Goddard
Space Flight Center in Greenbelt, Maryland, manages the mission. NASA's Jet
Propulsion Laboratory, a division of Caltech in Pasadena, manages the Mars
Reconnaissance Orbiter. Mars Express is a project of the European Space Agency;
NASA and the Italian Space Agency jointly funded the MARSIS instrument.
For more information about NASA's Mars missions, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
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