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This book depicts a vivid and vibrant image of modern Main Belt asteroid science. In the last decade, thanks to the exploration by the NASA Dawn mission and the advent of high-resolution Earth-bound observations, we have entered a renaissance of Main Belt asteroid science. Formation theories, dynamical models, meteorite geochemical data, remote and in-situ observations synergistically show asteroids are leftover building blocks of planetary formation and tracers of important evolutionary processes (e.g., collisions, orbital migration) that have shaped the evolution of the early Solar System. Planned missions such as NASA’s Lucy and Psyche (scheduled to launch in 2021 and 2022) will surely provide additional colorful strokes to our ever-evolving portrait of the Main Belt.
A search for volcanic and plutonic features on Vesta was an important driver for a geomorphological examination of the asteroid. Another goal was to determine if the asteroid was a protoplanet, one of the remnants of the material that formed the Solar System. Therefore, NASA’s Dawn spacecraft collected imaging, spectroscopic, and elemental abundance data, which were utilized to examine the asteroid’s surface. A digital terrain model was created and the asteroid’s various geomorphic features were analyzed. Large scale features include the Rheasilvia and Veneneia impact basins, the Divalia Fossae and Saturnalia Fossae trough sets, and the Vestalia Terra plateau. Small scale features include deposits of dark material, pitted terrain, pit crater chains, mass-wasting deposits, and impact craters. While these geomorphic analyses revealed no evidence of volcanism, evidence of magmatic activity on Vesta was identified. In addition, analysis of Vesta’s geomorphology suggests that it is not only a protoplanet, but also an intermediate body between asteroids and planets.
Carbon, central to astrobiology, shaped the development of the dwarf planet Ceres, a water-rich protoplanet explored by NASA’s Dawn mission. As a candidate ocean world, Ceres has the potential to provide new insights into prebiotic chemistry and habitability. This chapter reviews observations of carbon and organic matter on Ceres by Dawn and Earth-based telescopes. The observations are placed in context with astrophysical processes that produced organic matter in nebular materials from which Ceres grew. We consider mechanisms for destruction and synthesis of organic matter with changing hydrothermal conditions within Ceres’ interior. This is supported by studies of Ceres’ closest meteorite analogs, the aqueously altered carbonaceous chondrites, and halite crystals containing organic matter that may have formed within Ceres. Ultraviolet-, infrared-, and nuclear-spectroscopy show that Ceres’ surface contains a mixture of carbonates and organic matter in concentrations higher than the meteorite analogs. Ceres carbon-rich surface results from a combination of impacts and complex processes that occurred within Ceres’ interior, including low-temperature aqueous alteration, ice-rock fractionation, and modification of the accreted carbon species during serpentinization. This chapter reviews the current state of knowledge about carbon on Ceres, including sources of carbon and organics, parent body processes, remote sensing observations, and their interpretation.
The NASA Dawn mission, launched in 2007, aimed to visit two of the most massive protoplanets of the main asteroid belt: Vesta and Ceres. The aim was to further our understanding of the earliest days of the Solar System, and compare the two bodies to better understand their formation and evolution. This book summarises state-of-the-art results from the mission, and discusses the implications for our understanding not only of the asteroid belt but the entire Solar System. It comprises of three parts: Part 1 provides an overview of the main belt asteroids and provides an introduction to the Dawn mission; Part 2 presents key findings from the mission; and Part 3 discusses how these findings provide insights into the formation and evolution of the Solar System. This is a definitive reference for academic researchers and professionals of planetary science, asteroid science and space exploration.
Impact craters are the dominant landform on Mercury and range from the largest basins to the smallest young craters. Peak-ring basins are especially prevalent on Mercury, although basins of all forms are far undersaturated, probably the result of the extensive volcanic emplacement of intercrater plains and younger smooth plains between about 4.1 and 3.5 Ga. This chapter describes the geology of the two largest well-preserved basins, Caloris and Rembrandt, and the three smaller Raditladi, Rachmaninoff, and Mozart basins. We describe analyses of crater size–frequency distributions and relate them to populations of asteroid impactors (Late Heavy Bombardment in early epochs and the near-Earth asteroid population observable today during most of Mercury’s history), to secondary cratering, and to exogenic and endogenic processes that degrade and erase craters. Secondary cratering is more important on Mercury than on other solar system bodies and shaped much of the surface on kilometer and smaller scales, compromising our ability to use craters for relative and absolute age-dating of smaller geological units. Failure to find “vulcanoids” and satellites of Mercury suggests that such bodies played a negligible role in cratering Mercury. We describe an absolute cratering chronology for Mercury’s geological evolution as well as its uncertainties.
Boulders are ubiquitous on the surfaces of asteroids and their spatial and size distributions provide information for the geological evolution and collisional history of parent bodies. We identify more than 200 boulders on near-Earth asteroid 4179 Toutatis based on images obtained by Chang'e-2 flyby. The cumulative boulder size frequency distribution (SFD) gives a power-index of −4.4 ± 0.1, which is clearly steeper than those of boulders on Itokawa and Eros, indicating much high degree of fragmentation. Correlation analyses with craters suggest that most boulders cannot solely be produced as products of cratering, but are probably survived fragments from the parent body of Toutatis, accreted after its breakup. Similar to Itokawa, Toutatis probably has a rubble-pile structure, but owns a different preservation state of boulders.
We show that we can obtain a good fit to the present-day stellar-mass functions of a large sample of young and old Galactic clusters with a tapered Salpeter power-law distribution function with an exponential truncation of the form dN/dm ∝ mα [1 − exp(−m/mc)β]. The average value of the power-law index α is ~−2.2, very close to the Salpeter value of −2.3, while the characteristic mass, mc, is in the range 0.1–0.6M⊙ and does not seem to vary in any systematic way with the present cluster parameters such as metal abundance, total cluster mass or central concentration. However, the characteristic mass shows a remarkable correlation with the dynamical age of the cluster, namely mc/M⊙ ≃ 0.15 + 0.5 × t3/4dyn, where tdyn is the dynamical time, taken as the ratio of cluster age and dissolution time. The small scatter around this correlation is likely due to uncertainties on the estimated value of tdyn. We attribute the observed trend to the onset of mass segregation through two-body relaxation in a tidal environment, causing preferential loss of low-mass stars from the cluster and hence a drift of the characteristic mass towards higher values. If dynamical evolution is indeed at the origin of the observed trend, it seems plausible that globular clusters, now with mc ≃ 0.35M⊙, were born with a stellar mass function very similar to that measured today in the youngest Galactic clusters and with a value of mc around 0.15 M⊙. This is consistent with the absence of a turn-over in the mass function of the Galactic bulge down to the observational limit at ~0.2M⊙ and argues for the universality of the initial mass function of Population I and II stars.
The discovery of an increasing number of extrasolar planets (EPs) prompts the development of a planetary taxonomy. Such analysis, as in many other fields of research, is useful to identify groups of objects sharing similar traits. When applied to extrasolar planets, the taxonomy may provide a valid support for disentangling the role of the several physical parameters (semimajor axis, metallicity etc.) involved in the planetary formation processes and subsequent evolution. We present the state-of-the-art for exoplanets taxonomy obtained with hierarchical algorithms and the definition of robust clusters of planets (this is an update of the taxonomy published in Marchi 2007). The physical relevance of the exoplanet clusters along with their implications for the formation theories are also discussed. Finally, we comment on the future improvements of such analysis taking into account new algorithms and new input variables.
Clair Gough, Research Associate Research Associate at Manchester School of Management, UMIST and at the Tyndall Centre for Climate Change Research, UK,
Éric Darier, Greenpeace Canada,
Bruna De Marchi, Head of the Mass Emergencies Program (PEM) Institute of International Sociology of Gorizia (ISIG), Italy,
Silvio Funtowicz, Head of the Knowledge Assessment Methodologies Sector European Commission Joint Research Center,
Robin Grove-White, Professor Institute for Environment, Philosophy and Public Policy, Furness College, Lancaster University, UK; Chair Lancaster University's Centre for the Study of Environmental Change (CSEC),
Ângela Guimarães Pereira, Scientific Officer Institute for the Protection and Security of the Citizen,
Simon Shackley, Lecturer in Environmental Management and Policy Environmental Management and Policy, Manchester School of Management, UMIST,
Brian Wynne, Professor of Science Studies Institute for Environment, Philosophy and Public Policy at Furness College, Lancaster University, UK
Climate change represents one of society's most challenging environmental concerns and has been a major factor in changes in the way that environmental policies are debated and informed. Climate change policy faces at least three major challenges: (1) what is known – or not known – about climate change, in particular regarding the relative importance of anthropogenic factors; (2) what can and should be done; and (3) who should do something about it?
Since the 1992 Rio Earth Summit, these challenges have been addressed in several ways: (a) by increasing research and international sharing and integration of expertise on climate change (e.g., the Intergovernmental Panel on Climate Change); (b) by developing international agreements on issues such as the reduction of carbon dioxide emissions; and (c) by promoting national/local strategies to fulfil international agreements (e.g., Local Agenda 21 – community defined strategies for sustainable development arising from the first “Earth Summit” held in Rio in 1992). These challenges all include policy and scientific aspects but also raise questions over the interpretation of Local Agenda 21 (Tuxworth 1996; Selman and Parker 1997; Voisey et al. 1996; Young 1996; Young 1997). How local is “local”? What kind of “agenda” is “Agenda 21”? Whose “agenda” is it? Answers to these questions vary according to the perspectives and purposes of those asking the questions in the first place.
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