Mars

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Introduction to Mars
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Announcements

• Reading Assignment
• Finish Chapter 13
• Quiz today
• Will cover all material since the last exam.
  This is Chapters 9-12 and the part of 13 covered
  today.
• Exam 2 next Thursday
• Brief review after Tuesdays lecture
• Next study-group session is next Wednesday (3/28)
  from 1030AM-1200Noon in room 330.
• Public lecture next Tuesday (3/27) 730PM in
  308 of Kuiper (this room). Prof. Bob Brown,
  Saturn seen through infrared eyes
• Look for PTYS/ASTR206 sign-up sheet (our class!)
• Note Prof. Brown will conduct a limited number
  of special 10-minute tours of the VIMS Operations
  Center these tours will originate in the Atrium
  at 6PM early arrival is recommended!

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• Today
• Basic facts of Mars
• Marss apparitions / orbit / appearance from
  Earth
• Exploration
• Surface (start)
• Tuesday
• Surface (finish)
• Interior
• Atmosphere
• Water on Mars
• Moons
• Life (time permitting otherwise, this will be
  discussed later in the course)

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Introduction to Mars

• 4th planet from the Sun
• Avg. distance 1.524 AU
• Eccentricity 0.093
• Year 686.98 days
• Day 24.62 hours
• Almost the same (differs only by about ½ hour)
• Diameter 6,794 km
• About ½ the size of Earth
• Mass 6.418 x 1023 kg
• About 10 times less than Earth
• Surface temp
• Max 70 oF
• Min -220 oF
• Mean -63 oF

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Mars Apparitions

• Mars is best seen from Earth every synodic
  period. That is every 780 days. During this
  time, Mars is at opposition and rises to its
  highest point in the night sky at midnight.
• During the month or so on either side of this,
  Mars is bright in the sky and is very obvious
• also known as an apparition
• Because of Marss elliptical orbit, some
  oppositions are more favorable than others
• An especially good apparition occurred in 2003
  when Mars was at its closest to Earth in over
  50,000 years.

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Synodic vs. Sidereal Orbital Period

• Sidereal Period The time it takes a planet to
  complete a single orbit about the Sun (as seen
  from the stars)
• Synodic Period Time interval for a planet to
  return to the same position relative to the Sun
  and Earth (i.e. the time between successive
  oppositions)
• Mars has the longest synodic period of ALL the
  planets

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Synodic vs. Sidereal Periods
MARS
EARTH
SUN
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Synodic vs. Sidereal Periods
6 months later
SUN
EARTH
MARS
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Synodic vs. Sidereal Periods
MARS
1 year later
EARTH
SUN
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Synodic vs. Sidereal Periods
1.5 years later
MARS
EARTH
SUN
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Synodic vs. Sidereal Periods
2 years later
EARTH
SUN
MARS
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Synodic vs. Sidereal Periods
1 Synodic Period Later
SUN
EARTH
MARS
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Earth-Based Views of Mars
Ground-based telescope
Hubble Space Telescope
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A Gallery of my attempts summer of 2003


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Early Observations

• Astronomers in the 1600s made the first
  telescopic observations of Mars
• They determined
• Rotation period (24 h 37m)
• Presence of ice caps
• 25o tilt
• Linear features
• Canali (italian for channels)
• Mistranslated as canals

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Percival Lowell

• Background
• Wealthy Bostonian
• Brother was president of Harvard
• Sister won a Pulitzer prize in poetry
• Math degree from Harvard
• Decided to build an observatory in Flagstaff
• Realized importance of seeing conditions
• After the Mars craze, spent the rest of his life
  searching for planet X
• Saw LOTS of canals

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Lowells interpretation

• Canals carry water from Ice caps to civilizations
  in the agricultural regions
• The civilizations were dying of thirst
• Evidence for intelligent life on Mars

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Canals Reality

• They are not there !
• Lowell almost certainly was playing connect the
  dots
• An easy trap to get into
• Observing fine details on small objects through a
  telescope is a tough business!
• Note that they could magnify the images
  considerably, but that atmospheric turbulence
  limits what can be seen at such high magnification

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Optical effects againThe Face on Mars

• This was seen in Viking mission images
• Suggestive of something built by a civilization
• Not proposed by a scientist
• Scientists never accepted this interpretation

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The Face at higher resolution as seen with Mars
Global Surveyor MOC camera
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More familiar features
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A History of Mars Exploration

• Mariner 4 (1965)
• Found that Mars has many craters

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A History of Mars Exploration

• Mariner 4 (1965)
• Found that Mars has many craters
• Mariner 9 (1971)
• Found several enormous Volcanoes
• Not so dead !

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A History of Mars Exploration

• Mariner 4 (1965)
• Found that Mars has many craters
• Mariner 9 (1971)
• Found several enormous volcanoes
• Not so dead !
• Viking (1976)
• Lander, Compete map of surface (Face on mars)
• Biological experiments (no life!)

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More Recent (and Future) Mars Missions

• Mars Pathfinder (1997)
• Mars Global Surveyor (1997)
• Both missions in 1999 failed
• Stupid mistakes
• Mars Odyssey (2001)
• Water on Mars! (UA instrument)
• Mars Express (rover Beagle failed) (2003)
• Mars Exploration Rovers Spirit and Opportunity
  (2003)
• These are still going strong (would make for an
  excellent mission update)
• 05 Mars Reconnaissance Orbiter
• Successful orbit insertion
• HIRISE (UA instrument) you have GOT to check
  out their website!!!
• 07 Phoenix lander (UA mission!)

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HiRISE view of a rover next to Victoria crater
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Another HiRISE image

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Marss surface

• The heavily cratered southern highlands are older
  and about 5 km higher in elevation than the
  smooth northern lowlands
• Fewer craters in the Northern lowlands
• The origin of Marss crustal dichotomy is not
  completely understood
• One giant impact basin ?
• Multiple large impact basins ?
• Plate tectonics ?

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Valles Marineris

• A rift valley that separates the Northern and
  southern regions
• 3000-miles long
• As much as 6 miles deep in places
• formed by upwelling plumes of magma in the mantle

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Marss Volcanoes

• Olympus Mons is an enormous shield volcano
• 27 km high
• 20 times wider than it is high
• It is not active, and neither is any other
  volcano on Mars
• Mars has the largest shield volcanoes in the
  solar system

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Marss Craters

• Mars is much more heavily cratered than the Earth
  and Venus
• Has regions with similar crater density to that
  found at Mercury and the Moon
• The largest (more than 50km wide) and smallest
  (less than 5 km) craters are similar to those
  found on the Moon and Mercury

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Splosh Craters

• Medium sized craters ( 10-20 km) have large
  ejecta blankets which come in a variety of
  shapes
• Pancakes
• Flowers (as shown)
• May be due to subsurface water
• Like a pebble in mud
• NOT CLEAR !

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Marss Interior

• Density is 3950 kg/m3.
• This is somewhat less than Earth's density.
• Also, Mars is smaller than the Earth, so it could
  have cooled off more inside.
• Sulfur rich?
• Magnetic field
• Mars has no global magnetic field.