494 research outputs found
Exploring the Kuiper Belt: Design of trajectories for long-term Kuiper Belt exploration
No full textPrevious trajectory proposals with the purpose of exploring the Kuiper Belt have been limited to identifying trajectories to fly by a single pre-selected Kuiper Belt Object (KBO). Furthermore, these proposals were often limited to high-velocity flybys that pass through the Kuiper Belt in a limited number of years, or are based on the assumption of significant and uncertain technological advances. This thesis investigates the existence of currently feasible trajectories which position a spacecraft inside the Kuiper Belt for a significantly longer period of time. The feasibility of these trajectories is based on the assumption of current technological capabilities and a launch date between the years 2025 and 2040. To model these unique trajectories the conventional MGA-1DSM trajectory model is adapted in order to optimize trajectory problems that aim to reach the Kuiper Belt. The use of powered flybys is excluded in these problems in order to reduce problem and mission complexity. Optimization of the trajectory problems was done by performing an interactive multi-objective optimization approach with four distinct objectives on a set of twenty planetary sequences. The high complexity of these problems in combination with conflicting multiple objectives was found to necessitate an iterative optimization process using the pooled results of several algorithms in order to obtain satisfactory results. The optimization algorithm performance was further enhanced using various encouragement methods. By using the established optimization method multiple routes were identified that all culminate in a long-duration flight through the Kuiper Belt. The best results were found with planetary flyby sequences VVEJS, EVEEJN, and JN. The required launch energy (C3) for these trajectories ranges from 16 km² /s² , for sequences utilizing multiple inner planet flybys, to 75.5 km²/s² , for solutions utilizing adirect Jupiter-Neptune route. The maximum onboard delta V capability required for these solutions is 400 m/s. The flight time to the inner boundary of the Kuiper Belt ranges from 14.6 to 24 years. All thesetrajectories feature a flight time through the Kuiper Belt of well over or close to 100 years. In addition, it was found that trajectories that conclude their planetary flyby sequence with a Jupiter-Neptune leg are found to be especially well suited for long-duration Kuiper Belt flight.Aerospace Engineerin
Trajectory Optimization Methods for Low-Thrust Kuiper Belt Flyby Missions
No full textThe Kuiper belt is one of the last mostly unexplored regions in the Solar System. Exploration of the Kuiper belt can greatly increase humanity's understanding of the Solar System's formation and evolution. The use of low-thrust propulsion for Kuiper belt missions has the potential to improve the payload mass of the mission due to the high efficiency of its propellant. This research looks at the required methodology to optimize low-thrust trajectories with Kuiper belt object flybys. The trajectory is modelled using Tudat with spherical shaping as the trajectory parameterization method. A methodology is constructed which switches between high-thrust and low-thrust legs to constrain the input space for the low-thrust optimization problem. By using close-approach graphs and optimizing multiple flybys at the same time a trajectory with two Kuiper belt object flybys is found. The result is a robust method to find Kuiper belt object flyby trajectories with low-thrust propulsion.Aerospace Engineerin
Visueel & dynamisch: De stedebouw van Granpré Molière en Verhagen 1915-1950
No full textDe vernieuwing van een in formalisme en academisme vastgelopen vormentaal van architectuur en stadsuitleg tekende zich in de eerste helft van deze eeuw af in twee stromingen: de ene hechtte grote waarde aan zintuiglijke, visuele kwaliteiten en het gebruik van natuurlijke materialen, waarbij grote aandacht werd gegeven aan het specifieke en individuele in de opgave; de andere zocht naar de uiterste zuiverheid van expressie, hetgeen noodzaakte tot eliminatie van wat bijkomstig scheen, waarbij het algemene prioriteit kreeg boven het individuele. Deze stromingen ten onrechte vereenvoudigd tot Delftse School versus het Nieuwe Bouwen of tot Traditionalisme versus Functionalisme komen rond 1950 in hoofdzaak weer in één bedding samen. Ir J.A. Kuiper, schrijver van deze studie, behoort tot de tweede generatie architecten en stedebouwkundigen in het door Granpré Molière en Verhagen in 1916 opgerichte bureau, dat thans als Kuiper Compagnons zijn voortzetting vindt.ArchitectureArchitectur
Memory, Residence and Profession:Aspects of the process of reconversion of a Dutch noble family in the twentieth century
No full textThe author discuss questions like: how did noble men and women cope with the rise of totalitarian regimes and with the dramatic periods of the Second World War and the Cold War? What was the impact of the Fall of the Berlin Wall? And how did nobles react to the loss of political and economic privileges? In spite of all the variety and heterogeneity in wealth, power, prestige, and public visibility of these nobilities, some remarkable general trends and patterns emerge from the articles. This chapter shows how and why relatively many nobles succeeded in staying on top or in transforming political and economic capital into cultural and symbolic capital
Memory, Residence and Profession:Aspects of the process of reconversion of a Dutch noble family in the twentieth century
No full textThe author discuss questions like: how did noble men and women cope with the rise of totalitarian regimes and with the dramatic periods of the Second World War and the Cold War? What was the impact of the Fall of the Berlin Wall? And how did nobles react to the loss of political and economic privileges? In spite of all the variety and heterogeneity in wealth, power, prestige, and public visibility of these nobilities, some remarkable general trends and patterns emerge from the articles. This chapter shows how and why relatively many nobles succeeded in staying on top or in transforming political and economic capital into cultural and symbolic capital
Memory, Residence and Profession:Aspects of the process of reconversion of a Dutch noble family in the twentieth century
No full textThe author discuss questions like: how did noble men and women cope with the rise of totalitarian regimes and with the dramatic periods of the Second World War and the Cold War? What was the impact of the Fall of the Berlin Wall? And how did nobles react to the loss of political and economic privileges? In spite of all the variety and heterogeneity in wealth, power, prestige, and public visibility of these nobilities, some remarkable general trends and patterns emerge from the articles. This chapter shows how and why relatively many nobles succeeded in staying on top or in transforming political and economic capital into cultural and symbolic capital
Nawoord: Over veldwerk en antropologie als wetenschap
No full textSince the 1970s anthropologists write in a more reflexive way about their fieldwork. Anthropologist and travel author Gerrit Jan Zwier wrote a book about the rise of this genre. He asked the historian and anthropologist Yme Kuiper to add an epilogue to a new edition of his classic (first published in 1980)
Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects
No full textSinger, K.N., et al., "Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects." Science 363, 6430 (March 2019): p. 955-9 doi 10.1126/SCIENCE.AAP8628 ©2019 Author(s)The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions with other Kuiper belt objects (KBOs) with diameters from ~40 kilometers to ~300 meters, smaller than most KBOs observed directly by telescopes. We find a relative paucity of small craters ≲13 kilometers in diameter, which cannot be explained solely by geological resurfacing. This implies a deficit of small KBOs (≲1 to 2 kilometers in diameter). Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System. ©201
OSSOS. XXVI. On the Lack of Catastrophic Collisions in the Present Kuiper Belt
No full textWe investigate different conditions, including the orbital and size-frequency distribution (SFD) of the early Kuiper Belt, that can trigger catastrophic planetesimal destruction. The goal of this study is to test if there is evidence for collisional grinding in the Kuiper Belt that has occurred since its formation. This analysis has important implications for whether the present-day SFD of the cold classical trans-Neptunian objects (TNOs) is a result of collisional equilibrium or if it reflects the primordial stage of planetesimal accretion. As an input to our modeling, we use the most up-to-date debiased OSSOS++ ensemble sample of the TNO population and orbital model based on the present-day architecture of the Kuiper Belt. We calculate the specific impact energies between impactor-target pairs from different TNO groups and compare our computed energies to catastrophic disruption results from smoothed particle hydrodynamics simulations. We explore different scenarios by considering different total primordial Kuiper Belt masses and power slopes of the SFD and allowing collisions to take place over different timescales. The collisional evolution of the Kuiper Belt is a strong function of the unknown initial mass in the trans-Neptunian region, where collisional grinding of planetesimals requires a total primordial Kuiper Belt mass of M > 5 M ⊕, collision speeds as high as 3 km s−1, and collisions over at least 0.5 Gyr. We conclude that presently, most of the collisions in the trans-Neptunian region are in the cratering rather than disruption regime. Given the low collision rates among the cold classical Kuiper Belt objects, their SFD most likely represents the primordial planetesimal accretion. © 2022. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
An Analysis of the Statistics of the Hubble Space Telescope Kuiper Belt Object Search
No full textWe calculate statistical limits to the detection of Kuiper belt objects in the Hubble Space Telescope (HST) data of Cochran et al., in which they report the discovery of a population of Halley-sized objects in Pluto-like orbits. Detection of a population of faint objects in these data is limited by the number of false objects that appear owing only to random noise; the number of real objects must exceed the uncertainty in the number of these false objects for the population to be observable. We determine the number of false objects expected owing to random noise in the data of Cochran et al. by measuring the pixel-to-pixel noise level in the raw HST data and propagating this noise through the detection method employed by Cochran et al. We find that the uncertainty in the number of false objects exceeds by 2 orders of magnitude the reported number of objects detected by Cochran et al. The detection of such a population of Halley-sized Kuiper belt objects with these data is therefore not possible
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