Mars: Crash Course Astronomy #15

Introduction to Mars

• Mars as an object of fascination in human history.

  • Associated with the god of war in ancient civilizations.

  • Featured extensively in science fiction.

  • Now viewed as a potential destination for human exploration.

Basic Characteristics of Mars

• Fourth planet from the Sun and outermost terrestrial planet.

• Distance from the Sun: approximately 200 million kilometers.

• Closest distance to Earth remains about 60 million kilometers.

• Average surface temperature: -60 degrees Celsius.

• Size: Roughly half the size of Earth.

• Appears as a bright red object in the night sky.

  • Red coloration from oxidized iron (rust).

  • Coated in fine-grained dust, volcanic rock (basalt) contributes to surface coloring.

Surface Geography of Mars

• Distinct northern and southern hemispheres:

  • Northern Hemisphere: smooth plains.

  • Southern Hemisphere: cratered, hilly highlands.

• Evidence of a massive impact in the past that formed a large northern basin.

  • Results in lower elevation in the northern hemisphere compared to the southern.

• Major surface features include:

  • Tharsis Bulge: Home to the largest volcanoes in the solar system, including Olympus Mons.

    • Evidence of past tectonic activity on Mars.

  • Valles Marineris: A massive canyon that is 4000 km long, 200 km wide, and 7 km deep, significantly larger than the Grand Canyon.

Polar Ice Caps and Atmosphere

• Mars has polar ice caps primarily made of water ice, with seasonal layers of dry ice (frozen CO2).

  • Seasonal changes create fierce winds and dynamic surface conditions.

• Atmosphere of Mars:

  • Very thin, with surface pressure less than 1% of Earth.

  • Predominantly carbon dioxide, with seasonal freezing and thawing phenomena.

  • Exposed to frequent asteroid and comet impacts due to lack of atmospheric protection.

Geological Activity and Weather on Mars

• Interaction of atmosphere with the surface leads to:

  • Winds that move dust and create various dune formations.

  • Occurrence of dust devils, similar to tornadoes, which shape the landscape.

• Recent discovery of avalanches occurring on cliffs in spring thawing.

Moons of Mars

• Mars has two small moons: Phobos and Deimos.

  • Characteristics:

    • Phobos: 25 km in diameter, orbits very close to Mars, predicted to crash into Mars in the distant future.

    • Deimos: 15 km, also resembles asteroids in composition and appearance.

  • Both moons can transit the Sun, creating observable phenomena from Mars's surface.

Water on Mars

• Evidence of frozen water exists at the poles and mid-latitudes.

• Historical geology suggests Mars may have had significant quantities of flowing water and possibly oceans in the past.

• Current speculation on Mars's potential for past life due to environments that could support it:

  • Past climate likely warmer with thicker atmosphere before loss of magnetic field and atmospheric erosion.

Current Research and Future Exploration

• Increased focus on the potential for past or present life due to the presence of organic molecules detected by the Curiosity rover.

• Continued exploration missions have revealed much about Mars in modern science, despite high failure rates for missions.

• Plans for human missions to Mars; potential habitats could be underground caves formed by ancient lava flows.

  • Possibility of exploration from these protected sites against harsh Martian conditions.

Conclusion

• Summary of key points:

  • Mars is colder and smaller than Earth, with distinct geography and a history of water.

  • Current atmosphere is thin and composed mainly of carbon dioxide.

  • Ongoing research hints at Mars's complex geological history and potential for past life.

  • Future human exploration is being actively discussed and planned.