Week 7: Mars

LECTURE 3: History of Mars Observations

Mars

  • named after god of war because Mars is red

Opposition:

  • Opposition: when an object is on the opposite side of Earth from the sun

    • Mars can be observed all night when it is at opposition

      • it rises at sunset and sets at sunrise

        • mars is close and bright at opposition

    • Mercury and Venus cannot be in opposition because it is closer to the sun than earth and has a smaller orbit than Earth

Mars’s Surface Features (as seen back in the day)

  • only major planet with observable (from earth) surface features

  • changing polar ice caps

  • light and dark areas that change with “seasons”

1659: Christiaan Huygens

  • Huygens observed the “rotating Triangle”, indicating Mars may be rotating


1666: Giovanni Cassini

  • Cassini determined the rotation period of Mars to be 24 hours and 37 minutes

1770: William Herschel

  • Herschel determined that Mars had an axial tilt of 25 degrees

    • Mars has Seasons!

    • Mars is very similar to Earth

1877: Giovanni Schiaparelli

  • Schiaparelli mapped the surface of Mars

    • “Canali” = Italian for channels

      • channels are natural waterways

      • was mistranslated to English as “canals”

        • “canals” = creature-made waterways = creature-made waterways

1894: Percival Lowell

  • Lowell because obsessed with seeing “canals” on Mars

    • build his Mars Hill Observatory

  • charted 160 canals that he believed channeled water from the Mars’s poles to the cities (on the equator)

    • but because the lens on his telescope, it is thought he was seeing blood vessels in his eyes instead of actual channels on Mars

Authors taking advantage of Idea of Mars taking over

The War of Worlds by H.G. Wells (1898)

  • book about Mars taking attacking Earth because they’ve ran out of water

Mars in Science Fiction

  • Edgar Rice Burroughs by John Carter of Mars

  • Fake news broadcast causing panic

LECTURE 4: Mars Features and Properties

Properties of Mars

  • Mars is named: after Roman god of war

  • rotation rate: 24 hours and 37 minutes

  • Mars Diameter: 4,200 miles or 0.5 Earth diameters or 0.5 🜨 (Earth) diameters

  • Mass: 1/10th 🜨(earth) Mass

  • Surface gravity: 0.38 gravity

  • axial tilt: 35 degrees

  • surface temperature:

    • minimum: -220 degrees F

    • maximum: 70 degrees F

    • average: -80 degrees F

      • indicates that Mars atmosphere is thinner than Earths

Mars’s Atmosphere

  • Mars’s atmosphere is thin

    • appears sort of reddish-pink from suspended dust

  • Mars’s atmosphere contains:

    • 95% carbon dioxide

    • 1% of Earth’s atmospheric pressure

  • Daily surface winds: 10-20 mph

  • dust storms with wind speeds exceeding 300 mph

Mars’ orbit

  • average orbital velocity is slower than Earth’s orbit

    • due to Mars being further from the sun than Earth

  • average distance from sun = 141,700,595 miles = 1.5 AU

  • period of revolution: 1.9 years

  • Aphelion: farthest point from sun

  • perihelion: closest point to the sun

Surface of Mars

  • Largest volcano in the Solar System: Olympus Mons (Mount Olympus)

    • Largest volcano in the Solar System is located on Mars

      • no active vulcanism or plate movement

  • Largest Canyon in the solar system: Valles Marineris (Valley of the Mariner)

    • Largest Canyon in the Solar System is located on Mars

  • Largest (confirmed) impact basin in the solar system: Hellas Basin

    • Largest impact basin in the Solar System is located on Mars

Olympus Mons

  • Largest volcano in the Solar System: Olympus Mons (Mount Olympus)

    • Largest volcano in the Solar System is located on Mars

      • no active vulcanism or plate movement

    • 300 mile diameter

    • 15 miles high (2.5x larger than Mount Everest)

      • if standing on top of Olympus Mons = in space

        • if standing on top, human eye can only see Olympus Mons

    • Caldera: 60 miles across

    • largest volcano in the Solar System

      • same size as the state of Arizona

Why can Martian Volcanos get so big?

  • Mars does not have plate tectonic moving

    • results in volcanos accumulating vast amounts of magma over time, allowing them to grow larger without the displacement typical on Earth.

Valles Marineris

  • Largest Canyon in the solar system: Valles Marineris (Valley of the Mariner)

    • Largest Canyon in the Solar System is located on Mars

    • 3,000 miles long

    • 4 miles deep

    • 60 miles across

      • total length is the size of the whole united states

Hellas Basin

  • Largest (confirmed) impact basin in the solar system: Hellas Basin

    • Largest impact basin in the Solar System is located on Mars

Martian Soil

  • appears reddish-pink

    • 54% Silicon Oxide

    • 19% iron oxide (rust)

      • Not blood!

Evidence of Water Flow

  • Mars had a thick atmosphere and liquid water for the first 0.5 billion years

  • last rain storm would have been 4 billion years ago

Ancient Outflow Channels

Ancient Outflow Channels

Ancient Streams

Ancient Streams

Ancient Martian Shoreline

Ancient Martian Shoreline

Salty Water Flows

  • liquid water boils on surface of mars because pressure is so low

    • salty water melts, during spring melts, and flows down mountainsides

      • salt in water raises boiling point

Salty Water Flows

Polar Caps

  • Permanent North and South polar ice caps grow and shrink with the seasons

    • contains water and some carbon dioxide

    • unlike Earth, perihelion/aphelion significantly influences the seasons

      • at Northern Polar cap, always has water ice

      • at Southern Polar cap, has water and CO2 ice

Mars’s Satellites

  • Mars has 2 natural Satellites

    • Mercury has 0 Satellites

    • Venus has 0 Satellites

    • Earth has 1 Satellite

    • Mars has 2 Satellites

      • only other planet that has natural satellites

      • small

LECTURE 5: Missions to Mars

Viking 1 and Viking 2

  • Viking 1 and Viking 2 are the first spacecrafts to land on mars

    • Viking 1 = 1976

  • Snow on Mars, but its CO2

    Snow on Mars, but its CO2

Mars Pathfinder (1997)

  • Pathfinder’s Rover: Sojourner

    • Sojourner was the first rover on Mars

Two More Rovers: Spirit and Opportunity

  • Opportunity was Mars’s longest lasting rover

    • lasted for 14 years

Another Rover: Curiosity

  • Curiosity is the oldest rover that is operational

    • landed in 2012 and is still operational (16 years)

    • Curiosity found more evidence of ancient rivers

Sky Crane

  • sky crane was a technology used during the landing of the Curiosity rover, designed to gently lower the rover onto the Martian surface.

Perseverance

  • perseverance is the most recent, functional rover on Mars

    • launched in 2020

    • landed in 2021

  • Ingenuity: Perseverance’s little helicopter buddy