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Mars Schiaparelli’s “Canals” Schiaparelli’s “Canals” Schiaparelli: More little green men… Still more little green men… Invading Earth? The broadcast The movies The book… The image… … in higher resoluion! More illusions: Pyramids Happy Faces! Even More illusions: Mars vs. Earth 50% Earth’s radius, 10% Earth’s mass 1.5 AU from the Sun Thin CO2 atmosphere Little greenhouse effect =>Main difference: Mars is SMALLER Mars is “Earthlike” Axis tilt about the same as Earth Similar rotation period (25 hours/”day”) Sunrise & Sunsets! Weather! => Could we survive? Martian Year (686 Earth days) Seasons on Mars Seasons on Mars are more extreme in the southern hemisphere because of its elliptical orbit. A Martian Sunset… Storms on Mars Seasonal winds on Mars can drive huge dust storms. Mars’ Moons: Fear & Death Exploring Mars Exploring Mars Exploring Mars Mars 1969A (USSR) March 27, 1969. The Mars orbiter did not reach Earth orbit. Mars 1969B (USSR) April 2, 1969. The Mars orbiter failed during launch. Mariner 8 (U.S.) May 8, 1971. The Mars orbiter failed during launch. Kosmos 419 (USSR) May 10, 1971. The orbiter achieved Earth orbit only. •Mars 5 launched July 25, 1973. The Mars orbiter arrived but lasted only a few days. •Mars 6 launched Aug. 5, 1973., but the lander failed due to a fast impact. •Mars 7 launched Aug. 9, 1973., but the lander missed the planet. Exploring Mars Viking (1976) Exploring Mars Sojourner (NASA) – 1997 Bounced to a safe landing Exploring Mars Spirit & Opportunity (NASA) – 2004+ Exploring Mars Mars Science Lab (NASA) – 2013 + “Curiosity” Looking for Capability of Life Exploring Mars Opportunity (2004 – 16 and still going…) Exploring Mars MAVEN (2013) Exploring Mars ExoMars (ESA) – Crashed last month… Water on Mars Water on Mars? Water on Mars What geological features tell us water once flowed on Mars? What geological features tell us water once flowed on Mars? The surface of Mars appears to have ancient riverbeds. Eroded crater The condition of craters indicates surface history. Close-up of eroded crater The Martian Surface Map Volcanoes…as recent as 180 million years ago… Past tectonic activity… A *even bigger* volcano A *really* GRAND canyon… Differences in Hemispheres Low-lying regions may once have had oceans. Low-lying regions may once have had oceans. Opportunity Spirit NASA’s SPIRIT & OPPORTUNITY Rovers…still sending data! 2004 Opportunity rover provided strong evidence for abundant liquid water on Mars in the distant past. How could Mars have been warmer and wetter in the past? © 2015 Pearson Education, Inc. Clumps of rounded pebbles discovered by the Curiosity rover compared with similar formations in Earth streambeds Today, most water lies frozen underground (blue regions). Some scientists believe accumulated snowpack melts carve gullies even today. Why did Mars change? Climate Change on Mars No widespread surface water for 3 billion years. Greenhouse effect probably kept surface warmer before. Somehow Mars lost most of its atmosphere. Climate Change on Mars Magnetic field may have preserved early Martian atmosphere. Solar wind may have stripped atmosphere after field decreased because of interior cooling. Polar Climate Change Exploring Mars Winds on Mars Wind trails from “dust devils” Rivers on Mars … & Earth! … More evidence of water Carbon Dioxide Cycle • How do atmospheres of Venus & Mars differ in their ability to cycle CO2 from atmosphere to crust and back?? Carbon Dioxide Cycle • Assume all 3 planets had similar compositions and conditions “early” in the solar system’s history… • Assume all 3 had liquid water, active volcanoes, and CO2 in atmosphere Carbon Dioxide Cycle Step 1: Evaporation/Rain 1 • Liquid water evaporates • Condenses into clouds in lower atmosphere • Rain falls through atmosphere forming Carbonic Acid (H2CO3) CO2 gas is absorbed Carbon Dioxide Cycle Step 2: Mineral Erosion by Acid Rain • Carbonic Acid (H2CO3) in rivers erodes rocks • Carbonate (CO32-) ion picked up in minerals washed to ocean • Calcium easily absorbed 2 CO2 is carried to oceans Carbon Dioxide Cycle Step 3: Tying Carbon into Rocks & Life! 3 • Calcium from rocks forms CaCO3 (Calcium Carbonate) • CaCO3 = Limestone • CaCO3 = Coral, Mollusk shells! CO2 accumulates on seafloor Carbon Dioxide Cycle Step 4: Tectonics & Subduction! 4 • Tectonics gradually pulls seafloor down • CaCO3 broken back into CO2 & other minerals CO2 now inside crust Carbon Dioxide Cycle Step 5: Volcanic Outgassing! • 5 Eventual Volcanic Activity pushes CO2 back into atmosphere CO2 now in atmosphere again! Carbon Dioxide Cycle Mars Feedback Loop Failure Evaporation • Rain • CO2 gas flushed out But… • Interior cools off • Volcanoes Stop! • 1 5 Carbon Dioxide Cycle Mars Feedback Loop Failure • Atmosphere CO2 decreases • Planet freezes 1 5 Carbon Dioxide Cycle Venus Feedback Loop Failure 1 5 Too Hot for clouds to form low enough But… Volcanoes don’t stop! Carbon Dioxide Cycle Venus Feedback Loop Failure • 1 • • • No Rain NO CO2 gas absorbed More CO2 added! Runaway Greenhouse Effect!