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From page 299... ... QUESTION 8: CIRCUMPLANETARY SYSTEMS 299 Q8.4 HOW DO PLANETARY MAGNETOSPHERES INTERACT WITH SATELLITES AND RINGS, AND VICE VERSA? The co-rotating charged particles of outer planet magnetospheres interact with the surfaces and atmospheres of the moons and rings embedded in the magnetospheres and erode them. Read the entire page →
From page 300... ... 300 ORIGINS, WORLDS, AND LIFE FIGURE 11-5 Top panel: Saturn's radiation belts as structured by the rings and inner moons, with gaps owing to the absorption of energetic protons by the moons and rings, and with the highest-energy (giga-electron volt [GeV] Read the entire page →
From page 301... ... QUESTION 8: CIRCUMPLANETARY SYSTEMS 301 and morphology of these rings. Similarly, both the prevalence and evolution of the dusty spokes over Saturn's B-ring are clearly influenced by seasonal changes in the magnetospheric environment. Read the entire page →
From page 302... ... 302 ORIGINS, WORLDS, AND LIFE Strategic Research for Q8.4 • Quantify material sources, sinks, and mass transport between Jupiter's magnetosphere and moons via in situ magnetic field and plasma measurements. • Characterize the magnetospheric interactions between Uranus and Neptune's atmosphere, moons, and rings with observations of planetary aurorae, measurements of satellite and ring exospheres and ionospheres, in situ measurements of the global distribution of the plasma composition, density, velocity and temperature, neutral density and composition, and charged dust in both the orbital plane of the moons and rings and at high inclinations. Read the entire page →
From page 303... ... QUESTION 8: CIRCUMPLANETARY SYSTEMS 303 more tenuous ring systems dominated by fine debris released from larger bodies can provide information about dust production, transport, and loss in different environments (Hedman et al. Read the entire page →
From page 304... ... 304 ORIGINS, WORLDS, AND LIFE Q8.5c What Is the Life Cycle of Planetary Rings? Recent measurements of the total mass of Saturn's rings and the mass flux between those rings and the planet indicate that the composition and mass of Saturn's rings may change substantially on timescales of hundreds of millions of years, which is much shorter than the age of the solar system (Waite et al. Read the entire page →
From page 305... ... QUESTION 8: CIRCUMPLANETARY SYSTEMS 305 • Constrain the origin of Phobos and Deimos, including whether they arose from past martian rings, by determining their bulk composition and interior structure by in situ geochemical and geophysical measurements. • Determine whether equatorial ridges on worlds like Iapetus, Pan, and Atlas are produced by the deposition of ancient rings or by other processes, with a combination of high-resolution remote sensing observations of equatorial ridges, and theoretical models for ring collapse and other competing hypotheses. Read the entire page →
From page 306... ... 306 ORIGINS, WORLDS, AND LIFE Crida, A., S Charnoz, H.W. Read the entire page →
From page 307... ... QUESTION 8: CIRCUMPLANETARY SYSTEMS 307 O'Donoghue, J., L Moore, J Read the entire page →
From page 308... ... Q9 PLATE: Earth, viewed from above the Moon's surface by the Lunar Reconnaissance Orbiter in 2015. SOURCE: Courtesy of NASA/GSFC/Arizona State University. Read the entire page →
From page 309... ... 12 Question 9: Insights from Terrestrial Life What conditions and processes led to the emergence and evolution of life on Earth; what is the range of possible metabolisms in the surface, subsurface, and/or atmosphere; and how can this inform our understanding of the likeli hood of life elsewhere? Astrobiology is a holistic field of research into the origin, evolution, and distribution of life in the universe.1 As such, planetary science and astrobiology encompass a continuous spectrum spanning the multidisciplinarity of life and physical sciences and investigate the codependence and coevolution of life and the environment. Read the entire page →
From page 310... ... 310 ORIGINS, WORLDS, AND LIFE TABLE 12-1 Extremophiles Nomenclature and Ranges Low → Higha pH Hyperacidophile Acidophile Neutrophile (pH 5–9) Alkaliphile (.pH 9) Read the entire page →
From page 311... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 311 FIGURE 12-1 Generalized model of biogeochemical cycling of energy and essential elements (CHNOPS) on Earth. Read the entire page →
From page 312... ... 312 ORIGINS, WORLDS, AND LIFE Q9.1a How Was the Emergence and Evolution of Life on Earth Influenced by Volatiles, Impacts, and Planetary Evolution in Early Solar System Environments? What were the principal components of the early solar system environment and how did controls on these components (such as available volatile inventory, volatile delivery via impacts and comets, and compositional changes in response to large impacts and planetary evolution) Read the entire page →
From page 313... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 313 molecules in chemical and biological systems. These approaches, which form the basis of systems chemistry and systems biology, can enhance our knowledge of abiotic synthetic routes to the building blocks of life and to possible pathways that the earliest forms of life on Earth, or life elsewhere, might have adopted. Read the entire page →
From page 314... ... 314 ORIGINS, WORLDS, AND LIFE FIGURE 12-2 Question 9. Order of prebiotic and origin of life events (left) Read the entire page →
From page 315... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 315 FIGURE 12-3 Universal phylogenetic trees over the past 30 years. Read the entire page →
From page 316... ... 316 ORIGINS, WORLDS, AND LIFE Q9.1f What Does the Last Universal Common Ancestor (LUCA) Represent (e.g., a Single Individual, a Species, or a Population of Species) Read the entire page →
From page 317... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 317 FIGURE 12-4 Representative idealized cross section of Earth's crust showing the diversity of so-called extreme habitable environments and their approximate location. SOURCE: Merino et al. Read the entire page →
From page 318... ... 318 ORIGINS, WORLDS, AND LIFE FIGURE 12-5 Microscopic images of life at environmental extremes on Earth, including (a) a fungal-prokaryote colony in vesicular basalt, Koko Seamount, Pacific Ocean, 67.5 m below the seafloor; (b) Read the entire page →
From page 319... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 319 energy released through organisms' metabolic functions, as chemicals react back toward equilibrium (see Figure 12-1; NASEM 2019a) Read the entire page →
From page 320... ... 320 ORIGINS, WORLDS, AND LIFE to adapt to poly-extremes. Laboratory and modeling studies, along with research in Earth environments, allow us to probe the fringes of this multi-dimensional space, and the effect on biological potential. Read the entire page →
From page 321... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 321 latter providing critical endmembers likely to be applicable to the search for life off-Earth (Onstott et al. Read the entire page →
From page 322... ... 322 ORIGINS, WORLDS, AND LIFE FIGURE 12-6 Plot using submarine vent data from the mid-ocean ridges in the Atlantic Ocean and Caribbean Sea to illustrate how the cumulative energy theoretically available from water–rock interactions for chemolithotrophic microbial metabolism is subject to multilateral co-variability. Key parameters include physical conditions under which water and rocks react in the subsurface (shown = pressure, temperature; not shown = flow rate) Read the entire page →
From page 323... ... QUESTION 9: INSIGHTS FROM TERRESTRIAL LIFE 323 create energy sources (e.g., methane and molecular hydrogen) to support life (Schrenk et al. Read the entire page →

From page 299...

... QUESTION 8: CIRCUMPLANETARY SYSTEMS 299 Q8.4 HOW DO PLANETARY MAGNETOSPHERES INTERACT WITH SATELLITES AND RINGS, AND VICE VERSA? The co-rotating charged particles of outer planet magnetospheres interact with the surfaces and atmospheres of the moons and rings embedded in the magnetospheres and erode them.