The Terrestrial Planets, Part III

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The Terrestrial Planets,Part III

• Mars

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MARSThe God of War
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Physical Data

• Diameter 6,794 km (0.531 Dearth)
• Mass 6.40x1027 g (0.107 Mearth)
• Density 3.96 g/cm3
• Rotation Period 24.6 hours
• Tilt of Axis 25o
• Surface Temperature 130-290 K

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Physical Data

• Orbital Semi-major Axis 1.524 AU
• Orbital Period 1.881 years
• Orbital Inclination 2o
• Orbital Eccentricity 0.093
• Surface Gravity 0.38 Earth Gravity

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Physical Data

• Satellites 2
• Magnetic Field no
• Surface Pressure 0.01 Earths Pressure

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Mars Interior
CRUST ( aluminum silicates )

• Relatively small core size compared to the mantle
• Smallest core of all the terrestrial
  planets compared to the overall volume
  (9)
• Exact composition of mantle is unknown

3393 km
1520 km
CORE ( iron iron sulfide )
MANTLE ( iron-magnesium silicates ? )
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Mars Atmosphere

• Clouds

Planet-wide Clouds ( from Hubble)
A Cyclonic Event
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Mars Atmosphere

• 95 Carbon Dioxide
• 2.7 Nitrogen
• 1.6 Argon
• 0.6 Carbon Monoxide
• 0.15 Oxygen
• 0.03 Water Vapor (variable)

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Mars Surface

• Polar Caps
• Composed of both carbon dioxide and water
• South Polar Cap
• Consists mainly of frozen carbon dioxide.
• This cap never melts completely.
• This picture shows it at its minimum size of 400
  km (249 miles).

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Mars Surface

• North Polar Cap
• Consists of mainly water-ice.
• Seasonal Changes
• When spring begins in a hemisphere, the
  corresponding cap shrinks as the carbon dioxide
  turns directly into a gas.

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Mars Surface

• Polar caps change in size depending on the
  Martian seasons.

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Mars Surface
500 km

• Olympus Mons
• Largest mountain (volcano) in the Solar System
• 24 km (78,000 ft) high
• Base is 500 km in diameter
• Rimmed by a 6 km (20,000 ft) high cliff

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Mars Surface

• Valles Marineris
• Huge canyon
• Would stretch coast to coast across the U.S.
• It is 4000 km (2500 miles) long and up to 6 km (4
  miles) deep

4000 km
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Mars Surface
Flight over the Martian Terrain, including Valles
Marineris and Three Volcanos
m
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Mars Surface

• Viking Lander
• Landed in Chryse Planitia on July 20, 1976
• Took panoramic pictures of the surface
• On-board experiments tested soil for signs of
  life. Results were inconclusive.

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Mars Surface
Viking Photos To the right Morning ground
frost Below Panorama and Mars pink sky.

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Mars Surface

Pathfinder Photos
Rover and Yogi Martian Sunset
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Mars Surface

• Water on Mars?
• There is evidence of liquid water once flowing
  over the surface of Mars.
• Fluvial Features
• Created by water flowing around a crater (right).
  Probably caused by a flood.

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Mars Surface

• Dry Riverbeds
• Created by slow erosion of running water.

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Mars Surface

• Dust Storms
• Mars surface winds churn up surface material
• Storm sizes range in size from small local
  dust-devils to plumes that sweep over the
  entire planet (right)

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Mars Moons
PHOBOS
Phobos is Greek for fear Mars innermost
moon Size 27 x 21.6 x 18.8 km

Above Crater Stickney Left Image by Soviet
spacecraft Phobos 2, launched in 1988
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Mars Moons

• DEIMOS
• Deimos is Greek
• for panic
• Smallest known moon
• in the solar system
• 15 x 12.2 x 11 km

Phobos and Deimos are probably captured asteroids
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Martian Myths of Yesterday

• Canals of Mars
• Discovered by G.V. Schiaparelli in 1877
• Percival Lowell (below) built an observatory in
  1894 pricipally for the study of the Martian
  canals
• The canals are actually optical illusions

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Martian Myths of Today

• The Face
• Lies in the Cydonia region, a region of
  weathered, isolated hills
• One hill resembling a face was photograghed by
  Viking 1

Some people believe this is a monument built by a
Martian intelligence, and that other
surface features resemble pyramids, cities, and
fortresses