Mars

Some similarities between Mars & Earth Mars’ Bulk Properties Mars has days & seasons like Earth

Many differences between Mars & Earth Mars’ Bulk Properties Mars has density similar to Moon Even though atmosphere of Mars is mostly CO 2 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 (CO 2 ) 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 –CO 2 bakes out of rocks Increased Temperature Increased Greenhouse Gases

Runaway Icehouse Effect Greenhouse gases decrease because: –rain washed CO 2 out of atmosphere –CO 2 locked into carbonate rocks –little geologic activity on Mars meant CO 2 remained trapped Decreased Temperature Decreased Greenhouse Gases

Runaway Icehouse Effect

Atmosphere Comparison Venus –Runaway greenhouse –Very high pressure (90 atm) –CO 2 : 96% –N 2 : 3.5% Earth –Moderate temperature –Moderate pressure (1 atm) –N 2 : 78% –O 2 : 21% –H 2 O: 1% Mars –Runaway icehouse –Low pressure (0.01 atm) –CO 2 : 95% –N 2 : 3% Even though Mars’ atmosphere is still mostly CO 2, there isn’t enough of it to raise the temperature significantly