Introduction to Mars for geologic mapping students

Summary

This session introduces the basics of Martian geology, covering Mars’s basaltic crust, the impact of past water activity, and the planet's geological features. It explores the available datasets, such as remote sensing images, rover-based observations, and mineralogical analyses, focusing on Gale Crater as a key example. The session highlights the role of various instruments, including the Mars Reconnaissance Orbiter and Curiosity Rover, in geological mapping. It emphasizes Mars's dry, frozen desert surface and the role of past water in shaping sedimentary rocks, while also noting the absence of large-scale tectonic features.

Takeaways

• 😀 Mars has Earth-like geological processes, such as erosion, wind, flowing water, and chemical weathering, allowing for similar geological mapping activities.
• 😀 Mars' crust is primarily basaltic, with numerous basaltic lava flows and large volcanoes, including the largest mountain in the solar system, Olympus Mons.
• 😀 Mars has a distinct northern and southern hemisphere dichotomy: the northern hemisphere is lowland and younger, while the southern hemisphere is older and more heavily cratered.
• 😀 The Mars Orbiter Laser Altimeter (MOLA) provides accurate topographic data, helping to define Mars' geological dichotomy between the lowlands and highlands.
• 😀 High-resolution imaging tools, such as the Mars Reconnaissance Orbiter's CTX and HiRISE cameras, capture detailed images of Mars' surface, useful for geological mapping.
• 😀 The PRISM spectrometer on orbiters can identify specific minerals on Mars by analyzing spectral data, detecting signatures of clay and iron-rich minerals.
• 😀 The Curiosity Rover, stationed in Gale Crater, uses multiple instruments like MOLLI and ChemCam to analyze rock textures and compositions, revealing past water activity.
• 😀 Gale Crater features sedimentary rock layers, including clays, which suggest that liquid water was present in the crater in Mars' ancient past.
• 😀 Mars lacks large-scale tectonic features such as thrust faults, limiting structural geology studies, but sedimentary processes can still be mapped and analyzed.
• 😀 Jezero Crater, the target for the Mars 2020 Perseverance Rover, shows signs of past water flow, including a bird-foot delta and clay-rich sediments, indicating potential past life.

Q & A

What is the primary geological composition of Mars?

Mars is primarily a basaltic world, meaning its crust is composed mostly of basaltic rocks. These rocks are formed from volcanic activity and make up much of the Martian surface.

What geological processes are currently active on Mars?

Mars is currently experiencing geological processes similar to those on Earth, such as erosion, wind activity, and possibly chemical weathering. However, the surface remains dry, cold, and frozen, with very little liquid water present.

What evidence do we have that Mars once had liquid water?

Evidence for liquid water on Mars comes from features such as channels, valleys, and sedimentary rock formations. These features suggest that water once flowed across the surface, enough to carve channels and move sediment.

What is the significance of the northern and southern hemispheres of Mars?

Mars has a distinctive dichotomy between its northern and southern hemispheres. The northern hemisphere consists of younger, flatter lowlands, while the southern hemisphere is older, more heavily cratered, and mountainous, forming a boundary known as the dichotomy.

How do Mars' topography and elevation vary across the planet?

Mars' topography varies significantly between the northern and southern hemispheres. The southern hemisphere features highland regions with older, more cratered terrain, while the northern hemisphere has lower-lying, younger, and smoother terrain. The Mars Orbiter Laser Altimeter (MOLA) has provided detailed topographic data showing this elevation contrast.

What role does the Mars Reconnaissance Orbiter play in studying the Martian surface?

The Mars Reconnaissance Orbiter (MRO) plays a crucial role in mapping Mars' surface. It carries high-resolution cameras such as the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE), which capture detailed images of Mars' surface at varying resolutions. These images help identify geological features and analyze the surface composition.

How does the Curiosity rover analyze the geology of Mars?

The Curiosity rover uses a variety of instruments to analyze Martian geology. These include the Mars Hand Lens Imager (MOLLI) for zooming in on rocks, ChemCam for laser-based chemical analysis, the Alpha Particle X-ray Spectrometer (APXS) for chemical composition, and the CheMin X-ray diffraction instrument to identify minerals.

Why was Gale Crater chosen as the landing site for the Curiosity rover?

Gale Crater was chosen as the Curiosity rover's landing site because it contains a diverse range of sedimentary rocks, including clay minerals, which are indicative of past water activity. The sedimentary layers in Gale Crater also provide an opportunity to study the stratigraphy and history of water on Mars.

What types of rocks and minerals have been discovered in Gale Crater?

In Gale Crater, the Curiosity rover has discovered sedimentary rocks like conglomerates, sandstones, and mudstones. These rocks contain a mixture of minerals such as plagioclase, olivine, magnetite, and clay minerals, suggesting a history of water-rich sedimentary processes.

What is the geological significance of Jezero Crater for future Mars exploration?

Jezero Crater is significant for future Mars exploration because it contains features that resemble a delta, suggesting that it once had a large, long-lived lake with water inflows and outflows. The presence of clay and carbonate minerals in Jezero Crater makes it an important target for the Perseverance rover in the search for past life.