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					Mars




  Now: ~ opposition (rises when?)
  magnitude -2.2
Popular Interest
Past and
present…
 1938: Radio
  broadcast of
  War of the
  Worlds
  panics US
 2000: “Red
  Planet”
 2005 (and
  1953) “War
  of the
  Worlds”
First Observations

First observed by
 Dutch physicist
 Christian Huygens,
 1659
 He noted…
                Rotation




Motion of the feature Syrtis Major and
concluded P=24h
Giovanni Cassini
   Determined to be
    24:37 who also saw
    the polar caps…
                 Polar Ice Caps
   Ice cap
    seen in
    this
    ground
    based
    photo

   Similar to
    view in
    scope
       Seasons and eccentricity




 Seasons are affected (made more extreme) because
  perihelion occurs at Southern Hemisphere summer
 This is unlike Earth seasons, since Earth’s orbital
  eccentricity is small
        Eccentricity and Oppositions
   Causes some
    oppositions
    to be
    “favorable”

   September
    2003’s was
    especially
    favorable

   Note angular
    size of Mars
       Giovanni Schiaparelli
 First proposed that
  the caps made of ice
 Became famous when
  he drew his sketch of
  Mars in 1877 …
“Canali” (channels/canals)
Percival Lowell

 Wealth “Boston
  Brahman” (social
  and cultural elite)
 Became interested
  in the Mars canals
  and established
  an observatory in
  Flagstaff, AZ
             Lowell at the scope
   Drew on 6-inch globes
    to accommodate
    perspective
            Edward Barnard

   In 1894 Edward
    Barnard and
    others could
    not convince
    himself the
    canals existed
      Mariner probes would resolve

   dust storm here
    frustrated first
    photos in 1971
    Mariner 9
              When cleared…

   Many features but
    none lined up with
    canals drawn by
    Schiaparelli or
    Lowell
Possible explanation based
on Lowell’s Venus “spokes”
   Doctors noted that
    Lowell had stopped
    his scope down to a
    few inches,
    effectively creating a
    pinhole camera at
    eye, which displays
    veins in retina

   Similar to
    ophthalmoscope, an
    instrument used to
    examine the interior
    of the eye
            Craters discovered




   Not evenly distributed…
     Mostly in southern hemisphere


    Dust has eroded
    rays and ejecta
             Volcanoes found




    Volcanoes such as Arsia Mons shown
    above and...
.. In perspective 3D
      The volcano Olympus Mons




   rises 24 km (15 miles) above plains! (3x Mt Everest).
   Great size of volcanoes on both Venus and Mars suggests no current
    plate tectonics ... same surface sits above hot spot.
    Tharsis Rise

 Olympus Mons and
  other volcanos
  comprise the
  Tharsis Rise
 Shown compared
  to eastern US here
 Is an average of 5 -
  6 km above most
  of surface
     Valley
    Marineris
 4000 km
  long
 Would span
  USA as
  shown
 It is a huge
  crust
  fracture
 not formed
  by water,
  but…
These channels were formed by massive water flow




                      But where is the water now?...
    Some water locked up in polar ice caps




   South pole shown here
   During summer CO2 portion sublimates, leaving H2O.
    (Temperature rises above sublimation point)
                color view of cap




   shows ice melted off of sun-facing slopes, revealing
    strange terraced slopes
                    North pole




   this is almost all residual water ice shown here
                                  Broken terrain
                                   from outflow




   in the Capri plateau, suggests water violently outgassed
    when heated by volcanic activity below
   Like similar event in eastern Washington state 14,000 years
    ago that created the Channeled Scablands
Some water seen in fog




Early morning fog in canyons
1975-6: Two Viking Landers
           Approaching Mars


 dawn view
  reveals clouds
  along volcano
  Olympus Mons,
  Valley Marineris
 CO2 snow in
  Argyre Basin
  Viking I
Lander View
 Landed in Chryse Planitia
  (Golden Plains)
 Shows edge of crater on
  horizon, probably
  responsible for jagged
  rocks in scene.
 Foreground shows
  regolith covered with
  other rocks that under
  closer examination ...
   …appear pocked (vesicular)




Suggests outgassing during igneous formation
Weather Report from mars
                 Other Results
    95% CO2, 2% N2, 1.6% Argon
    6-8 mBar pressure (Earth: 1000 mB)
    no ozone layer
    no magnetic field (therefore no iron core, also
    supported by low avg density 3.9)
   large temp swings ... -80OC to -20O C in warmer
    areas!
   seasonal pressure variationss as CO2 freezes
    out/sublimates
Scoop Delivered Soil to Experiments
           Geological Results
 surface rich in iron (magnet) --> rust red!
 silicon --> 2/3 of Mars..
 little interior info since one seismometer
  failed...



   Biological…
           gas-exchange




Sensed respiration of samples (used gas-
  chromatograph/mass spectrometer)
          labeled release




Used radioactive carbon nutrients -- checked for
 metabolism...
       pyrolytic-release




Checked for photosynthesis with
radioactive CO2 and artificial sunlight
          Biological Results
 no life found
 active chemical reactions believed due to
  release of peroxides & superoxides
 surface is literally antiseptic!
                Magnetosphere




 almost no magnetic field
 Thus, core, if iron, not liquid, since Prot ~ PEarth
 Thus solar wind and cosmic rays hit surface
July 1997: Pathfinder
    Mars Global
     Surveyor




 Imaging Mars from an orbit around it
 Recent image of delta-like fans
             Other probes…
   Mars Exploration
    Rover Spirit and
    Opportunity
    landed in
    January, 2004




                       Mars Odyssey continues
                         to map Mars in
                         infrared
          Rover Assignment
 Write up, in < 1 typed page…
 Current mission status (a paragraph)
 5 interesting things about the mission
 Use the link on our WebCT Class Links page
 Due next time (make a copy for yourself so
  we can discuss it)
    Asaph Hall

Discovered
two moons
in 1877
favorable
opposition
using the
26-inch
refractor at
the USNO, in
Washington,
DC
     150 years before the were
   “predicted” in Gulliver’s Travels

“They have likewise discovered two lesser Stars, or
  Satellites, which revolve about Mars; whereof
  the innermost is distant from the Center of the
  primary Planet exactly three of his Diameters,
  and the outermost five; the former revolves in
  the space of ten Hours, and the latter in
  Twenty-one and an Half; so that the Squares of
  their periodical Times, are very near in the same
  Proportion with the Cubes of their Distance from
  the Center of Mars; which evidently shews them
  to be governed by the same Law of Gravitation,
  that influences the other heavenly Bodies. “
                      Phobos




Phobos is nearer and larger, P = 7:39! – rise to set in 5h!
Not spherical – why not?
                         Deimos




Almost Marsynchronous -- appears to take 3 days horizon to horizon.

				
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posted:8/25/2012
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