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From page 209... ... 8 Question 5: Solid Body Interiors and Surfaces How do the interiors of solid bodies evolve, and how is this evolution recorded in a body's physical and chemical properties? How are solid surfaces shaped by subsurface, surface, and external processes? Read the entire page →
From page 210... ... 210 ORIGINS, WORLDS, AND LIFE Q5.1a How Much Variability in Composition and Internal Structure Is There Within and Between Solid Bodies, and How Did Such Variability Arise and Evolve? Many factors influence the initial structure of silicate bodies, including the interior oxidation state. Read the entire page →
From page 211... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 211 FIGURE 8-1 "Core" mass fraction for rocky (terrestrial) and icy bodies. Read the entire page →
From page 212... ... 212 ORIGINS, WORLDS, AND LIFE Q5.1b What Kinds of Internal Liquid Layers (e.g., Oceans) or Discrete Regions Occur in Solid Bodies, What Are Their Characteristics, Where Are They, and How Long Do They Persist? Read the entire page →
From page 213... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 213 of impurities present; thus, the temperature and ice content of the crust of icy bodies will control its mechanical properties. Particularly on small icy or rocky worlds, the low conductivity of the porous near-surface material will keep the interior warm, although high temperatures will close pores by viscous flow. Read the entire page →
From page 214... ... 214 ORIGINS, WORLDS, AND LIFE FIGURE 8-2 Internal evolution of selected solid surface bodies in the inner solar system. The conversion from geologic period boundaries to absolute ages uses commonly accepted values based on the estimated frequency of meteoroid impacts but is somewhat uncertain. Read the entire page →
From page 215... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 215 FIGURE 8-3 Diagram showing three different modes of planetary heat transfer, with various bodies as examples. As planets cool, melt production decreases and a heat-pipe planet may transition to plate tectonics or stagnant-lid heat transfer. Read the entire page →
From page 216... ... 216 ORIGINS, WORLDS, AND LIFE Q5.2b What Processes Control the Production and Evolution of Magnetic Fields? Within solid planetary bodies, dynamo-generated magnetic fields are typically produced by motion of conductive fluid within a metallic core. Read the entire page →
From page 217... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 217 Studying the composition of materials exposed on planetary surfaces, such as changing compositions of volcanic products erupted on the surfaces of rocky bodies and ocean worlds, thus provides an opportunity to reconstruct internal evolution and ongoing differentiation. For example, remote sensing data, in situ measurements of rocks by Mars rovers and analysis of martian meteorites record changes in composition that have been attributed to progressive cooling of the martian mantle (e.g., Baratoux et al. Read the entire page →
From page 218... ... 218 ORIGINS, WORLDS, AND LIFE Q5.3a What Internal Processes Control Surface Topography and Produce Tectonic Features? Surface topography is supported through a combination of dynamic, active processes (such as a plume of hot rising mantle material pushing up on the lithosphere, creating a topographic rise) Read the entire page →
From page 219... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 219 directly onto the surface, although they have been suggested to be more common on some planets and planetesimals (e.g., eucrites on Vesta) Read the entire page →
From page 220... ... 220 ORIGINS, WORLDS, AND LIFE Q5.3d Where and How Are Surfaces Modified by Hydrothermal/Geothermal Processes? Materials that have been mineralogically or geochemically altered by hydrothermal processes in the interior can be exposed on the surface, thus modifying its composition. Read the entire page →
From page 221... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 221 Q5.4 HOW HAVE SURFACE CHARACTERISTICS AND COMPOSITIONS OF SOLID BODIES BEEN MODIFIED BY, AND RECORDED, SURFACE PROCESSES AND ATMOSPHERIC INTERACTIONS? The surfaces of solid bodies record evidence of atmospheric interaction, and thereby provide information about how the atmosphere may have evolved through time (see also Question 6, Chapter 9) Read the entire page →
From page 222... ... 222 ORIGINS, WORLDS, AND LIFE related glacial activity may be occurring on Triton and on other dwarf planets in the Kuiper belt. These different ices and mixtures of ices create glaciers with distinct physical properties compared to Earth, so further study of such glacial processes is important for understanding and further investigating surface processes and their records on bodies farther out in the solar system. Read the entire page →
From page 223... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 223 weathering is on Mars, and what it can reveal about the presence (or absence) of surface water or groundwater, and the compounds dissolved into that water through Mars's history. Read the entire page →
From page 224... ... 224 ORIGINS, WORLDS, AND LIFE Charged particles (from the solar wind, and/or the relevant planetary magnetosphere for planetary satellites) collide with individual regolith grains and lose energy as they are implanted into grains, breaking bonds. Read the entire page →
From page 225... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 225 Developing a general understanding of how different space weathering processes modify the surfaces of p lanetary bodies and how those vary with local conditions will help to determine rates of geologic processes, understand duration of surface exposure of materials, understand surface composition, and provide a valuable framework that can be used to better interpret remote sensing observations across the solar system. Q5.5b How Have Impacts Affected Surface and Near-Surface Properties? Read the entire page →
From page 226... ... 226 ORIGINS, WORLDS, AND LIFE (Khurana et al. Read the entire page →
From page 227... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 227 Q5.6 WHAT DRIVES ACTIVE PROCESSES OCCURRING IN THE INTERIORS AND ON THE SURFACES OF SOLID BODIES? Activity is present on the surfaces and in the interiors of both rocky and icy bodies throughout the solar system. Read the entire page →
From page 228... ... 228 ORIGINS, WORLDS, AND LIFE planet's history. Despite abundant evidence for the work of volcanism in shaping the surfaces of the terrestrial planets and our own Moon, only Io is demonstrably volcanically active, although Venus has provided us with tantalizing hints of present-day volcanic eruptions. Read the entire page →
From page 229... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 229 FIGURE 8-4 Frequency of quakes as a function of size for different bodies. No seismometer has been placed on Europa. Read the entire page →
From page 230... ... 230 ORIGINS, WORLDS, AND LIFE weather regolith particles through formation of nanophase iron, also known as space weathering (Q5.5a) Read the entire page →
From page 231... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 231 SUPPORTIVE ACTIVITIES FOR QUESTION 5 • Measure optical constants of the range of materials expected in the solar system under relevant pressure and temperature conditions (from Venus to airless icy satellites) to serve as the basis by which we constrain the compositions of planetary surfaces from remote sensing data. Read the entire page →
From page 232... ... 232 ORIGINS, WORLDS, AND LIFE Jolliff, B.L., S.A. Wiseman, S.J. Read the entire page →
From page 233... ... QUESTION 5: SOLID BODY INTERIORS AND SURFACES 233 Stähler, S.C., A Read the entire page →
From page 234... ... Q6 PLATE: A view of Venus's atmosphere in the ultraviolet from the Akatsuki mission in 2016. Venus's north pole is to the top in this image. Read the entire page →

From page 209...

... 8 Question 5: Solid Body Interiors and Surfaces How do the interiors of solid bodies evolve, and how is this evolution recorded in a body's physical and chemical properties? How are solid surfaces shaped by subsurface, surface, and external processes?