Mars ASTR-3040 Astrobiology Day 18

Homework Chapter 8 Due Thurs. March 31 3, 7, 13, 23, 30, 32, 41, 46, 51, 52 Plus (49 or 50) if you've read one of the books or seen one of the movies.

Civilization Mars holds a special place in human fantasies about space and aliens. Herschels (lae 1700s)‏ Schiaparelli (1877)‏ Lowell (1895)‏  Canals  civilizations

Literature H.G. Wells – War of the Worlds (1898)‏ ER Burroughs Ray Bradbury

Movies Capricorn 1 Total Recall The Ghosts of Mars Mars Attacks

Exploration of Mars

Modern View Began in the late 1960s – Mariner 4, 6, 7  Dust storms, volcanoes, craters First landers – Vikings – 1976  No hard evidence of life, weather station, no liquid surface water.

Seasons 25 degree tilt vs for Earth orbital eccentricity 1.38 – 1.66 AU Strong winds driven by seasonal changes (temperature gradients)‏

Polar caps – change with seasons Water ice and Carbon Dioxide ice Phoenix lander (N. Pole) confirmed water ice. HST monitoring program Mars Global Surveyor

Dust Storms Dust Devils – Spirit rover HST monitoring program

Geological History Volcanoes  Big, shield type  Recent evidence of underground water Flowing water? Resurfacing in North

Surface evidence of water in the past. Pathfinder landed in what appears to be a floodplain. Spirit – Gustev crater – an ancient lake? Opportunity – rock structures are only seen in standing water environments on Earth (“blueberries”).

Mars Express orbiter images - floodwaters?

Water-carved channels on slopes of volcanoes. Hadriaca Patera (center). Flood channel?

Relief map. Was the entire northern hemisphere an ocean at one time? Blue is below “sea level”. Hydrogen content map. Blue is highest hydrogen area. Maybe the top meter or so contains water ice. Distributed mostly in the polar regions. Mars Water Today

Water flow gullies in crater rim. Slumping material at bottom. N.B. Fig in book is different. It shows recent changes which resemble water flow in last 4-5 years. Mars Global Surveyor image.

Mars Water Today View from Mars Express which resemble frozen ice rafts covered with soil. Similar patterns are seen on Earth in the Antarctic and on Europa.

Climate History Mars was most likely warmer and wetter in past. Today, thin atmosphere, weak greenhouse.  95% CO 2 In past, a thicker atmosphere would support a stronger greenhouse effect. 400 X as dense atmosphere;  Would give surface Pressure about 3 times that of Earth today;  Temperature above freezing Ocean hundreds of meters deep.

Why did Mars Change? Probably lost significant amount of CO 2. Core cooled and solidified  Loss of magnetic field  Solar wind stripping of atmosphere  UV breakdown of water  As cooled, oxygen would also leave or “rust” rocks Inverse greenhouse effect.

Is Mars Habitable? Liquid water is the key. Probably was 2-3 Gyr ago, but for how long? Not habitable at the current time. Terraforming