Solar System - Mars

Overview

  • Course: Astrobiology The Solar System I: Mars.

  • Focus on the geological history, atmosphere, water presence, and exploration of Mars.

Distance and Size of Mars

  • Distance from Earth: 55 - 400 million km; average distance is approximately 225 million km.

  • Size: Mars's diameter is about half that of Earth, with a comparable dry landmass.

  • Geological Formation: Mars differentiated into crust, mantle, and core within a few tens of millions of years after Solar System formation.

Geological History of Mars

  • Timeline of Geologic Eras:

    1. Pre-Noachian:

      • Presence of a magnetic field.

      • Massive impact craters from asteroid collisions.

    2. Noachian:

      • Evidence of river channels and lakes suggests a surface water cycle.

    3. Hesperian:

      • Global volcanic resurfacing occurred alongside catastrophic floods.

      • Significant loss of atmosphere during this period.

    4. Amazonian:

      • Geological activity decreased significantly, resulting in a cold and dry climate.

      • Evidence of glaciers at non-polar latitudes due to changes in axial tilt.

Current Water Conditions on Mars

  • Atmospheric Pressure: Low pressure prevents liquid water from forming; ice sublimates directly to vapor.

  • Comparative Example: Earth's surface pressures and temperatures allow for the coexistence of water vapor, liquid, and ice.

  • Salts on Mars: Different salts can produce brines that remain liquid at lower temperatures, thus reducing freezing points.

  • Cryosphere: Most water is now locked as ice in a global cryosphere.

  • Geomorphological Evidence: Over 3 billion years ago, signs of abundant liquid water existed, such as delta deposits and river channels.

Exploration of Mars

  • Robotic Missions: Key missions include:

    • Curiosity Rover 2012 - present

    • Perseverance Rover 2021 - present

    • NASA's Mars Reconnaissance Orbiter

    • Mars Exploration Rovers

    • Phoenix Lander.

  • Historical Images:

    • 1965: First close-up image taken by NASA's Mariner 4.

    • 1971: 85% of the Martian surface was imaged.

    • Various landers (Soviet Mars 3, Viking Lander, etc.) contributed to surface imaging and data collection.

Habitability and Life Detection

  • Components of Habitability:

    • Essential Ingredients: Water, building blocks of life (CHNOPS), and energy sources (photosynthesis or chemosynthesis).

    • Examination of geological contexts for potential biosignatures.

  • Biosignatures: Indicators of past or present life, preserved in minerals.

  • Current Mars Conditions: Extreme surface conditions (high UV radiation, low pressure) versus protected subsurface environments that may harbor liquid water and life.

Extremophiles and Mars

  • Types of Extremophiles:

    • Psychrophiles: Survive in cold environments (glaciers, permafrost) still requiring liquid water.

    • Halophiles: Thrive in high-salt environments with potential modern brine-seeps on Mars indicated by seasonal features.

    • Acidophiles: Adapt to low pH geothermal areas and might exist in Martian analogue environments.

Future Exploration of Mars

  • Human Missions: Prospective plans for human exploration of Mars.

  • Assessment and Learning: Ongoing coursework will explore microbial biosignatures, extremophiles, and other planetary studies with emphasis on Mars.