Geological history of Mars
The sequence of processes that formed and reshaped Mars, from planetary accretion through crustal evolution, volcanism, impacts, and climate change.
Martian geologic time scale: A chronology dividing Martian history into the Noachian, Hesperian, and Amazonian periods. These periods organize the planet’s surface history by changing geological activity.
Planetary accretion: The growth of planets through collisions and accumulation of dust, rocks, and smaller bodies. Mars’s earliest history began as solid material accumulated in the young Solar System.
Mars Global Surveyor: A NASA orbiter that mapped Mars and measured its magnetic field, topography, and surface properties. Its observations revealed remanent crustal magnetism and refined the planet’s geological map.
Geological history of Earth: The sequence of geological processes and events that shaped Earth over billions of years. Earth’s active tectonics and abundant water provide a sharp comparison with Mars’s preserved ancient terrain.
Mars climate history: The history of atmospheric conditions, temperature, and water on Mars through geological time. The timing and duration of warm, wet conditions remain central questions in planetary history.
Noachian: The earliest major period of Martian surface history, marked by heavy impacts and extensive valley networks. Its ancient terrain preserves evidence for early crust formation and a wetter climate.
Planetary differentiation: The separation of a planet’s materials into layers according to density, producing structures such as a core, mantle, and crust. Differentiation established Mars’s internal layers and shaped its early thermal evolution.
Mars Reconnaissance Orbiter: A NASA spacecraft orbiting Mars since 2006 to study its surface, atmosphere, and subsurface. High-resolution imaging and spectroscopy expose layered deposits and changing surface features.
Geological history of Venus: The sequence of geological processes that shaped Venus, reconstructed from its surface and atmosphere. Venus offers a contrasting rocky planet with a dense atmosphere and uncertain surface age.
Loss of Mars's magnetic field: The decline of Mars’s ancient global magnetic field as its internal dynamo weakened or stopped. Its timing may explain how solar wind helped strip away the early atmosphere.