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AS101 Week 10 Lecture 2.docx

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Wilfrid Laurier University
Patrick Mc Graw

AS101 Week 10 Lecture 2 Mars  Distance from Sun: 1.5 au  Diameter: 6790km (0.53 of Earth's)  Orbital Period: 687 days  Rotation period: 24.6 hours o Rotation period is close to Earth day  Average Surface Temp: -63C Mars Atmosphere  95% carbon dioxide  Much thinner than Earth's: less than 1% of the density. What influences a planet's atmosphere?  Size matters: larger planets have stronger gravity and can more easily hold onto gases.  Temperature also makes a difference. (Hotter planets lose their atmospheres more quickly).  Volcanic activity (outgassing) can add to or replenish an atmosphere.  On Earth, life plays a big role. Mar's moons: Phobos and Deimos  Small and irregularly shaped (less than 30km across)  May be captured asteroids: composition appears to be different from the planet.  Greek words for fear and terror Mars: History of Exploration  First successful flyby: Mariner 4, 1965  First landings: Mars 2+3, 1971  Viking 1+2, 1975  About 40 missions so far  Currently Active: Curiosity rover Sunset on Mars  Sunset looks blueish whereas rest of Martian sky has redish colors  Reversed from Earth’s colors Why is Martian Sunset Blue?  On Earth, red light is enhanced and more of the blue light is getting out of the way, while this is opposite on Mars Water on Mars  Very little water vapour in the atmosphere, and liquid water cannot exist on the surface because of the low pressure.  Might have been life at one time  But ice exists a short distance below the surface, and polar ice caps consist of a mixture of water ice and frozen carbon dioxide (dry ice).  Surface features resembling water erosion on Earth, along with microscopic features in some rocks, suggest that there was liquid water earlier in the planet's history.  Evidence that there might have been water before Life on Mars  No sign of it now.  Could there have been life earlier, when there was liquid water?  So far, no clear evidence of it.  In 1996, a paper in Science by David MacKay suggested that a meteorite believed to be from Mars contained evidence of fossilized bacteria, but this interpretation remains controversial. Mars Curiosity River  Launched Nov. 26, 2011, landed Aug. 6, 2012  About the size of a car.  Goals include looking for evidence of present or past life.  Carries multiple cameras, a drill, laser “drills,” miniature laboratories to analyze rock and dust samples. Curiosity Landing Site  Landing site was selected in part because it is likely to have been a lakebed when Mars was wetter. Some Curiosity Findings  Clay minerals, other minerals that usually form in wet environments on Earth  Sedimentary ro
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