Mars

Mars

1. Water

   • Vital
     • Assess the planet's potential for harbouring life
     • Provide usable resources for future human exploration
   • "Follow the Water"
     • NASA's Mars Exploration Program (MEP) in the first decade of the 21st century
   • Along crater & canyon walls
     • thousands of features that resemble terrestrial GULLIES
       • Formation 1: Liquid water involved, probably from melting ice
       • Formation 2: Involved carbon dioxide frost or the movement of dry dust
   • Evidence that show that liquid water ONCE existed
     • Valley Network
       • Carved by runoff resulting from rain/snow in early Mars history
     • Ma'adim Vallis
       • Much bigger than the Grand Canyon
       • Thought to have been carved by flowing water early in Mars' history

2. Land

   • Red Surface
     • Much of the surface is deeply covered by finely grained iron oxide (rust) dust
     • Mars = Red planet (on night sky)
       • Iron oxide is prevalent on the surface = reddish appearance

3. Atmosphere

   • Mars HAS a atmosphere
     • Quite dusty atmosphere
       • Iron oxide dust (red) from surface can change the sky colour from the blue -> red
       • Cloud can be composed of either CO2 / water ice
   • Primarily composed of CO2
     • Greenhouse effect of he CO2 atmosphere is small because atmosphere is quite thin
     • Reverse Runaway Greenhouse Effect
       • As the GE diminished
         • Planet cooled
           • Causing even more CO2 to be absorbed into the surface layer
             • Results: Runaway to lower temp & decreasing levels of CO2 in the atmosphere
           • Climate condition changed
             • Water began to freeze
               • Most of the water today is locked in the permaforst layer under the surface
                 • With a little more contained in the planet's polar caps
   • Quite thin
     • Atmospheric pressure = 1/150 of Earth's atmospheric pressure
       • Overall, atmosphere similar to Venus
         • Venus - body crushed Mars - body explode
   • Surface Temperature
     • about 50K cooler than Earth
       • Mars further away from the Sun
   • Ancient Dense Atmosphere
     • Around 4bn years ago
       • Mars MAY had a fairly dense atmosphere
         • Planet was much warmer & liquid water was widespread
       • Sometime during the next bn years
         • most of the Martian atmosphere disappeared
           • Possible cause
             • Gradual erosion of the atmosphere by solar wind

4. Searching for Ancient Life

   • by Curiosity & Opportunity rovers
     • Running water + possible dense atmosphere in the past = suitable conditions for living

5. Two Moons (unlike Mercury & Venus)

   • Larger: Phobos (Fear)
   • Half of Phobos: Deimos (Panic)
     • Both named after sons of the war god
   • Tiny moons (unlike Earth)
     • Phobos = 150 times smaller than Earth's
     • Irregularly shaped & heavily cratered
       • Probably they were asteroids that were slowed & captured by the outer fringes of the early Martian atmosphere (which was probably much denser than today's)
     • Move in circular, equatorial orbits & tidally locked to Mars
       • Direct consequences of the tidal influence of Mars
     • Transits of the Moons
       • Rovers on Mars can view
       • Transits of Phobos
         • Partial eclipses of the Sun by Phobos