Comet/Asteroid Protection System (CAPS): Preliminary Space-Based System Concept and Study Results
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Observational Constraints on Surface Characteristics of Comet Nuclei
Observational Constraints on Surface Characteristics of Comet Nuclei Humberto Campins ([email protected] u) Lunar and Planetary Laboratory, University of Arizona Yanga Fernandez University of Hawai'i Abstract. Direct observations of the nuclear surfaces of comets have b een dicult; however a growing number of studies are overcoming observational challenges and yielding new information on cometary surfaces. In this review, we fo cus on recent determi- nations of the alb edos, re ectances, and thermal inertias of comet nuclei. There is not much diversity in the geometric alb edo of the comet nuclei observed so far (a range of 0.025 to 0.06). There is a greater diversity of alb edos among the Centaurs, and the sample of prop erly observed TNOs (2) is still to o small. Based on their alb edos and Tisserand invariants, Fernandez et al. (2001) estimate that ab out 5% of the near-Earth asteroids have a cometary origin, and place an upp er limit of 10%. The agreement between this estimate and two other indep endent metho ds provide the strongest constraint to date on the fraction of ob jects that comets contribute to the p opulation of near-Earth asteroids. There is a diversity of visible colors among comets, extinct comet candidates, Centaurs and TNOs. Comet nuclei are clearly not as red as the reddest Centaurs and TNOs. What Jewitt (2002) calls ultra-red matter seems to be absent from the surfaces of comet nuclei. Rotationally resolved observations of b oth colors and alb edos are needed to disentangle the e ects of rotational variability from other intrinsic qualities. -
Assessment of DEMO Reactors for Fusion Power Utilization
九州大学学術情報リポジトリ Kyushu University Institutional Repository Assessment of DEMO Reactors for Fusion Power Utilization Elserafy, Hatem Interdisciplinary Graduate school of Engineering Sciences, Kyushu University https://doi.org/10.5109/2174854 出版情報:Evergreen. 5 (4), pp.18-25, 2018-12. Green Asia Education Center バージョン:published 権利関係: EVERGREEN Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy, Vol. 05, Issue 04, pp.18-25, December 2018 (Review Article) Assessment of DEMO Reactors for Fusion Power Utilization Hatem Elserafy Interdisciplinary Graduate school of Engineering Sciences, Kyushu University, Japan *Author to whom correspondence should be addressed, E-mail: [email protected] (Received November 15, 2018; accepted December 27, 2018). Given the undeniable climate change caused by global warming, decreasing the carbon footprint by using alternative energy sources became necessary. Thermonuclear fusion energy is one of the strongest candidates when it comes to alternative energy sources since it is safe, has negligible carbon footprint and its yield is incomparable to any other alternative. Credential as fusion performance may be; feasibility and economic attractiveness are something to be considered. The next stage fusion reactors are called DEMOnstration (DEMO) and are being assessed by various sources in terms of performance. In this work, DEMO fusion reactors are to be reviewed and their specifications are to be analyzed in terms of feasibility, while demonstrating how the tritium fueling stage not only presents a challenge for calculating fusion power costs, but also that fusion energy requires further R&D before it can be integrated into the power grid. Keywords: thermonuclear fusion, DEMO, TBR. 1. Introduction thought of as the most promising unexploited energy source [6]. -
Discovery of Earth's Quasi-Satellite
Meteoritics & Planetary Science 39, Nr 8, 1251–1255 (2004) Abstract available online at http://meteoritics.org Discovery of Earth’s quasi-satellite Martin CONNORS,1* Christian VEILLET,2 Ramon BRASSER,3 Paul WIEGERT,4 Paul CHODAS,5 Seppo MIKKOLA,6 and Kimmo INNANEN3 1Athabasca University, Athabasca AB, Canada T9S 3A3 2Canada-France-Hawaii Telescope, P. O. Box 1597, Kamuela, Hawaii 96743, USA 3Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 Canada 4Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7, Canada 5Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA 6Turku University Observatory, Tuorla, FIN-21500 Piikkiö, Finland *Corresponding author. E-mail: [email protected] (Received 18 February 2004; revision accepted 12 July 2004) Abstract–The newly discovered asteroid 2003 YN107 is currently a quasi-satellite of the Earth, making a satellite-like orbit of high inclination with apparent period of one year. The term quasi- satellite is used since these large orbits are not completely closed, but rather perturbed portions of the asteroid’s orbit around the Sun. Due to its extremely Earth-like orbit, this asteroid is influenced by Earth’s gravity to remain within 0.1 AU of the Earth for approximately 10 years (1997 to 2006). Prior to this, it had been on a horseshoe orbit closely following Earth’s orbit for several hundred years. It will re-enter such an orbit, and make one final libration of 123 years, after which it will have a close interaction with the Earth and transition to a circulating orbit. -
Comparison of the Orbital Properties of Jupiter Trojan Asteroids and Trojan Dust Xiaodong Liu and Jürgen Schmidt
A&A 614, A97 (2018) https://doi.org/10.1051/0004-6361/201832806 Astronomy & © ESO 2018 Astrophysics Comparison of the orbital properties of Jupiter Trojan asteroids and Trojan dust Xiaodong Liu and Jürgen Schmidt Astronomy Research Unit, University of Oulu, 90014 Oulu, Finland e-mail: [email protected] Received 10 February 2018 / Accepted 7 March 2018 ABSTRACT In a previous paper we simulated the orbital evolution of dust particles from the Jupiter Trojan asteroids ejected by the impacts of interplanetary particles, and evaluated their overall configuration in the form of dust arcs. Here we compare the orbital properties of these Trojan dust particles and the Trojan asteroids. Both Trojan asteroids and most of the dust particles are trapped in the Jupiter 1:1 resonance. However, for dust particles, this resonance is modified because of the presence of solar radiation pressure, which reduces the peak value of the semi-major axis distribution. We find also that some particles can be trapped in the Saturn 1:1 resonance and higher order resonances with Jupiter. The distributions of the eccentricity, the longitude of pericenter, and the inclination for Trojans and the dust are compared. For the Trojan asteroids, the peak in the longitude of pericenter distribution is about 60 degrees larger than the longitude of pericenter of Jupiter; in contrast, for Trojan dust this difference is smaller than 60 degrees, and it decreases with decreasing grain size. For the Trojan asteroids and most of the Trojan dust, the Tisserand parameter is distributed in the range of two to three. Key words. meteorites, meteors, meteoroids – planets and satellites: rings – minor planets, asteroids: general – zodiacal dust – celestial mechanics – solar wind 1. -
Photometric Study of Two Near-Earth Asteroids in the Sloan Digital Sky Survey Moving Objects Catalog
University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects January 2020 Photometric Study Of Two Near-Earth Asteroids In The Sloan Digital Sky Survey Moving Objects Catalog Christopher James Miko Follow this and additional works at: https://commons.und.edu/theses Recommended Citation Miko, Christopher James, "Photometric Study Of Two Near-Earth Asteroids In The Sloan Digital Sky Survey Moving Objects Catalog" (2020). Theses and Dissertations. 3287. https://commons.und.edu/theses/3287 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. PHOTOMETRIC STUDY OF TWO NEAR-EARTH ASTEROIDS IN THE SLOAN DIGITAL SKY SURVEY MOVING OBJECTS CATALOG by Christopher James Miko Bachelor of Science, Valparaiso University, 2013 A Thesis Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements for the degree of Master of Science Grand Forks, North Dakota August 2020 Copyright 2020 Christopher J. Miko ii Christopher J. Miko Name: Degree: Master of Science This document, submitted in partial fulfillment of the requirements for the degree from the University of North Dakota, has been read by the Faculty Advisory Committee under whom the work has been done and is hereby approved. ____________________________________ Dr. Ronald Fevig ____________________________________ Dr. Michael Gaffey ____________________________________ Dr. Wayne Barkhouse ____________________________________ Dr. Vishnu Reddy ____________________________________ ____________________________________ This document is being submitted by the appointed advisory committee as having met all the requirements of the School of Graduate Studies at the University of North Dakota and is hereby approved. -
Mass of the Kuiper Belt · 9Th Planet PACS 95.10.Ce · 96.12.De · 96.12.Fe · 96.20.-N · 96.30.-T
Celestial Mechanics and Dynamical Astronomy manuscript No. (will be inserted by the editor) Mass of the Kuiper Belt E. V. Pitjeva · N. P. Pitjev Received: 13 December 2017 / Accepted: 24 August 2018 The final publication ia available at Springer via http://doi.org/10.1007/s10569-018-9853-5 Abstract The Kuiper belt includes tens of thousands of large bodies and millions of smaller objects. The main part of the belt objects is located in the annular zone between 39.4 au and 47.8 au from the Sun, the boundaries correspond to the average distances for orbital resonances 3:2 and 2:1 with the motion of Neptune. One-dimensional, two-dimensional, and discrete rings to model the total gravitational attraction of numerous belt objects are consid- ered. The discrete rotating model most correctly reflects the real interaction of bodies in the Solar system. The masses of the model rings were determined within EPM2017—the new version of ephemerides of planets and the Moon at IAA RAS—by fitting spacecraft ranging observations. The total mass of the Kuiper belt was calculated as the sum of the masses of the 31 largest trans-neptunian objects directly included in the simultaneous integration and the estimated mass of the model of the discrete ring of TNO. The total mass −2 is (1.97 ± 0.30) · 10 m⊕. The gravitational influence of the Kuiper belt on Jupiter, Saturn, Uranus and Neptune exceeds at times the attraction of the hypothetical 9th planet with a mass of ∼ 10 m⊕ at the distances assumed for it. -
Re-Examining the Role of Nuclear Fusion in a Renewables-Based Energy Mix
Re-examining the Role of Nuclear Fusion in a Renewables-Based Energy Mix T. E. G. Nicholasa,∗, T. P. Davisb, F. Federicia, J. E. Lelandc, B. S. Patela, C. Vincentd, S. H. Warda a York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD, UK b Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH c Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ, UK d Centre for Advanced Instrumentation, Department of Physics, Durham University, Durham DH1 3LS, UK Abstract Fusion energy is often regarded as a long-term solution to the world's energy needs. However, even after solving the critical research challenges, engineer- ing and materials science will still impose significant constraints on the char- acteristics of a fusion power plant. Meanwhile, the global energy grid must transition to low-carbon sources by 2050 to prevent the worst effects of climate change. We review three factors affecting fusion's future trajectory: (1) the sig- nificant drop in the price of renewable energy, (2) the intermittency of renewable sources and implications for future energy grids, and (3) the recent proposition of intermediate-level nuclear waste as a product of fusion. Within the scenario assumed by our premises, we find that while there remains a clear motivation to develop fusion power plants, this motivation is likely weakened by the time they become available. We also conclude that most current fusion reactor designs do not take these factors into account and, to increase market penetration, fu- sion research should consider relaxed nuclear waste design criteria, raw material availability constraints and load-following designs with pulsed operation. -
Origin and Evolution of Trojan Asteroids 725
Marzari et al.: Origin and Evolution of Trojan Asteroids 725 Origin and Evolution of Trojan Asteroids F. Marzari University of Padova, Italy H. Scholl Observatoire de Nice, France C. Murray University of London, England C. Lagerkvist Uppsala Astronomical Observatory, Sweden The regions around the L4 and L5 Lagrangian points of Jupiter are populated by two large swarms of asteroids called the Trojans. They may be as numerous as the main-belt asteroids and their dynamics is peculiar, involving a 1:1 resonance with Jupiter. Their origin probably dates back to the formation of Jupiter: the Trojan precursors were planetesimals orbiting close to the growing planet. Different mechanisms, including the mass growth of Jupiter, collisional diffusion, and gas drag friction, contributed to the capture of planetesimals in stable Trojan orbits before the final dispersal. The subsequent evolution of Trojan asteroids is the outcome of the joint action of different physical processes involving dynamical diffusion and excitation and collisional evolution. As a result, the present population is possibly different in both orbital and size distribution from the primordial one. No other significant population of Trojan aster- oids have been found so far around other planets, apart from six Trojans of Mars, whose origin and evolution are probably very different from the Trojans of Jupiter. 1. INTRODUCTION originate from the collisional disruption and subsequent reaccumulation of larger primordial bodies. As of May 2001, about 1000 asteroids had been classi- A basic understanding of why asteroids can cluster in fied as Jupiter Trojans (http://cfa-www.harvard.edu/cfa/ps/ the orbit of Jupiter was developed more than a century lists/JupiterTrojans.html), some of which had only been ob- before the first Trojan asteroid was discovered. -
Comet Section Observing Guide
Comet Section Observing Guide 1 The British Astronomical Association Comet Section www.britastro.org/comet BAA Comet Section Observing Guide Front cover image: C/1995 O1 (Hale-Bopp) by Geoffrey Johnstone on 1997 April 10. Back cover image: C/2011 W3 (Lovejoy) by Lester Barnes on 2011 December 23. © The British Astronomical Association 2018 2018 December (rev 4) 2 CONTENTS 1 Foreword .................................................................................................................................. 6 2 An introduction to comets ......................................................................................................... 7 2.1 Anatomy and origins ............................................................................................................................ 7 2.2 Naming .............................................................................................................................................. 12 2.3 Comet orbits ...................................................................................................................................... 13 2.4 Orbit evolution .................................................................................................................................... 15 2.5 Magnitudes ........................................................................................................................................ 18 3 Basic visual observation ........................................................................................................ -
Asteroid Regolith Weathering: a Large-Scale Observational Investigation
University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2019 Asteroid Regolith Weathering: A Large-Scale Observational Investigation Eric Michael MacLennan University of Tennessee, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation MacLennan, Eric Michael, "Asteroid Regolith Weathering: A Large-Scale Observational Investigation. " PhD diss., University of Tennessee, 2019. https://trace.tennessee.edu/utk_graddiss/5467 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Eric Michael MacLennan entitled "Asteroid Regolith Weathering: A Large-Scale Observational Investigation." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Geology. Joshua P. Emery, Major Professor We have read this dissertation and recommend its acceptance: Jeffrey E. Moersch, Harry Y. McSween Jr., Liem T. Tran Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Asteroid Regolith Weathering: A Large-Scale Observational Investigation A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Eric Michael MacLennan May 2019 © by Eric Michael MacLennan, 2019 All Rights Reserved. -
Template for Manuscripts in Advances in Space Research
DISCUS - The Deep Interior Scanning CubeSat mission to a rubble pile near-Earth asteroid Patrick Bambach1* Jakob Deller1 Esa Vilenius1 Sampsa Pursiainen2 Mika Takala2 Hans Martin Braun3 Harald Lentz3 Manfred Wittig4 1 Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 G¨ottingen,Germany 2 Tampere University of Technology, PO Box 527, FI-33101 Tampere, Finland 3 RST Radar Systemtechnik AG, Ebenaustrasse 8, 9413 Oberegg, Switzerland 4 MEW-Aerospace UG, Hameln, Germany * [email protected] Submitted to Advances in Space Research Abstract We have performed an initial stage conceptual design study for the Deep Interior Scanning CubeSat (DIS- CUS), a tandem 6U CubeSat carrying a bistatic radar as the main payload. DISCUS will be operated either as an independent mission or accompanying a larger one. It is designed to determine the internal macro- porosity of a 260{600 m diameter Near Earth Asteroid (NEA) from a few kilometers distance. The main goal will be to achieve a global penetration with a low-frequency signal as well as to analyze the scattering strength for various different penetration depths and measurement positions. Moreover, the measurements will be inverted through a computed radar tomography (CRT) approach. The scientific data provided by DISCUS would bring more knowledge of the internal configuration of rubble pile asteroids and their colli- sional evolution in the Solar System. It would also advance the design of future asteroid deflection concepts. We aim at a single-unit (1U) radar design equipped with a half-wavelength dipole antenna. The radar will utilize a stepped-frequency modulation technique the baseline of which was developed for ESA's technology projects GINGER and PIRA. -
Astrodynamic Fundamentals for Deflecting Hazardous Near-Earth Objects
IAC-09-C1.3.1 Astrodynamic Fundamentals for Deflecting Hazardous Near-Earth Objects∗ Bong Wie† Asteroid Deflection Research Center Iowa State University, Ames, IA 50011, United States [email protected] Abstract mate change caused by this asteroid impact may have caused the dinosaur extinction. On June 30, 1908, an The John V. Breakwell Memorial Lecture for the As- asteroid or comet estimated at 30 to 50 m in diameter trodynamics Symposium of the 60th International As- exploded in the skies above Tunguska, Siberia. Known tronautical Congress (IAC) presents a tutorial overview as the Tunguska Event, the explosion flattened trees and of the astrodynamical problem of deflecting a near-Earth killed other vegetation over a 500,000-acre area with an object (NEO) that is on a collision course toward Earth. energy level equivalent to about 500 Hiroshima nuclear This lecture focuses on the astrodynamic fundamentals bombs. of such a technically challenging, complex engineering In the early 1990s, scientists around the world initi- problem. Although various deflection technologies have ated studies to prevent NEOs from striking Earth [1]. been proposed during the past two decades, there is no However, it is now 2009, and there is no consensus on consensus on how to reliably deflect them in a timely how to reliably deflect them in a timely manner even manner. Consequently, now is the time to develop prac- though various mitigation approaches have been inves- tically viable technologies that can be used to mitigate tigated during the past two decades [1-8]. Consequently, threats from NEOs while also advancing space explo- now is the time for initiating a concerted R&D effort for ration.