Post on 21-Dec-2015
transcript
• Some similarities between Mars & Earth
Mars’ Bulk Properties
o2.25orbit equator to of nInclinatio
37m h24period Rotation
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• Mars has days & seasons like Earth
• Many differences between Mars & Earth
Mars’ Bulk Properties
K133 F-220C -140re temperatusurface Minimum
K293 F70C 20re temperatusurface Maximum
K220 F-63C -53re temperatusurface Average
kg/m 3934density Average
30.5km 6794-Diameter
0.11kg 1042.6- Mass
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Earth
Earth
DD
MM
• Mars has density similar to Moon
• Even though atmosphere of Mars is mostly CO2 there isn’t enough atmosphere for greenhouse effect to keep Mars warm
Intelligent Life on Mars?• In science fiction, Mars is one of the most
frequent sites for extra-terrestrial life forms• This has some basis in scientific discoveries that
have been misinterpreted
“Face” on Mars “Canals” on Mars
Viking 1, 1976 “Exploring Mars”, 1894
Intelligent Life on Mars?• In science fiction, Mars is one of the most
frequent sites for extra-terrestrial life forms• This has some basis in scientific discoveries that
have been misinterpreted
“Face” on Mars “Canals” on Mars
Mars Global Surveyor, 2001 Hubble Space Telescope, 2003
Water on Mars?
• No liquid water on Mars surface now
• Evidence water has flowed on surface of Mars in the past– ancient
riverbeds
Water on Mars?
• Evidence water has flowed on surface of Mars in the past– ancient floods– 1000 times the
flow rate of Mississippi R.
Water on Mars?
• Evidence water has flowed on surface of Mars in the past– canyons carved
by flowing water
Ice on Mars
• Although there is still no certain evidence that liquid water flowed on Mars’ surface, there is evidence of ice on Mars– polar ice caps
• dry ice (CO2)• water ice
Permafrost
• Subsurface ice
Permafrost
• Subsurface ice– Melted by
meteor strikes– Create mud
flows around crater
Life on Mars?
• Evidence of water on surface of Mars gives some hope for finding some forms of life
• Possibly extinct now
• No evidence there were ever any higher forms of life
Topography of Mars
• Mars appears to be divided into 2 very different parts
• Divided almost exactly along the equator
Topography of Mars• Northern lowlands
– northern hemisphere is nearly 5 km (3 mi) lower than southern hemisphere
• Southern highlands
Topography of Mars
• Fewer craters in northern hemisphere
• Northern lowlands are younger
Crustal Dichotomy
• Hypotheses– Massive impact from meteorite or asteroid
• similar to lunar maria
– Plate tectonic activity in Martian past• northern lowlands are new rock from crustal
spreading similar to Earth’s Atlantic Ocean
– Ancient ocean covered northern lowlands• young rocks are sedimentary rocks from bottom of
ocean
Geologic Features
• Olympus Mons– largest mountain in Solar System– 15 mi high
Geologic Features
• Valles Marineris– would stretch from Los Angeles to New York– 2500 mi long, 400 mi wide, 5 mi deep
Iron on Mars• Reddish color on surface of Mars due to
iron oxide (rust)• However, low density suggests no dense
iron core• Conclusions?
– Mars did not undergo large-scale chemical differentiation
– Must have a lower percentage of iron relative to other elements compared to other terrestrial planets
Runaway Greenhouse Effect
• Greenhouse gases increase because:– water boils out of
oceans
– CO2 bakes out of rocks
IncreasedTemperature
IncreasedGreenhouse
Gases
Runaway Icehouse Effect
• Greenhouse gases decrease because:– rain washed CO2
out of atmosphere
– CO2 locked into carbonate rocks
– little geologic activity on Mars meant CO2 remained trapped
DecreasedTemperature
DecreasedGreenhouse
Gases
Runaway Icehouse Effect
Atmosphere Comparison• Venus
– Runaway greenhouse
– Very high pressure (90 atm)
– CO2 : 96%
– N2 : 3.5%
• Earth– Moderate
temperature– Moderate
pressure (1 atm)
– N2 : 78%
– O2 : 21%
– H2O: 1%
• Mars– Runaway
icehouse– Low pressure
(0.01 atm)
– CO2 : 95%
– N2 : 3%
Even though Mars’ atmosphere is still mostly CO2, there isn’t enough of it to raise the temperature significantly