Stability and Motion around Equilibrium Points in the Rotating Plane-Symmetric Potential Field

This study presents a study of equilibrium points, periodic orbits, stabilities, and manifolds in a rotating plane symmetric potential field. It has been found that the dynamical behaviour near equilibrium points is completely determined by the structure of the submanifolds and subspaces. The non-degenerate equilibrium points are classified into twelve cases. The necessary and sufficient conditions for linearly stable, non resonant unstable and resonant equilibrium points are established. Furthermore, the results show that a resonant equilibrium point is a Hopf bifurcation point. In addition, if the rotating speed changes, two non degenerate equilibria may collide and annihilate each other. The theory developed here is lastly applied to two particular cases, motions around a rotating, homogeneous cube and the asteroid 1620 Geographos. We found that the mutual annihilation of equilibrium points occurs as the rotating speed increases, and then the first surface shedding begins near the intersection point of the x axis and the surface. The results can be applied to planetary science, including the birth and evolution of the minor bodies in the Solar system, the rotational breakup and surface mass shedding of asteroids, etc.Comment: 38 pages, 7 figures. arXiv admin note: text overlap with arXiv:1403.040

Summer Workshop on Near-Earth Resources

The possible large scale use of extraterrestrial resources was addressed, either to construct structures in space or to return to Earth as supplements for terrestrial resources. To that end, various specific recommendations were made by the participants in the summer study on near-Earth resources, held at La Jolla, California, 6 to 13 August, 1977. The Moon and Earth-approaching asteroids were considered. Summaries are included of what is known about their compositions and what needs to be learned, along with recommendations for missions designed to provide the needed data. Tentative schedules for these projects are also offered

Meteoroids: The Smallest Solar System Bodies

This volume is a compilation of articles reflecting the current state of knowledge on the physics, chemistry, astronomy, and aeronomy of small bodies in the solar system. The articles included here represent the most recent results in meteor, meteoroid, and related research fields and were presented May 24-28, 2010, in Breckenridge, Colorado, USA at Meteoroids 2010: An International Conference on Minor Bodies in the Solar System

On the Dynamics of Binary Asteroids Applied to DART Mission Target (65803) Didymos

NASA’s Double Asteroid Redirection Test (DART) mission will be the first full-scale demonstration of a kinetic impactor for planetary defense. On September 26, 2022, the DART spacecraft is expected to impact Dimorphos, the secondary component of the Didymos binary asteroid system. The DART impact will reduce Dimorphos’s relative orbital velocity, shrinking both its semimajor axis and orbit period. The mutual orbit period will then be measured us- ing ground- and space-based observations in order to deduce the momentum transfer efficiency, which is an important parameter in planetary defense that has never been measured experimentally at a realistic scale. This thesis comprises a set of studies on the spin and orbital dynamics of the Didymos system conducted in support of the DART mission. Owing to the close proximity of Didymos and Dimorphos and their irregular shapes, the mutual dynamics are non-Keplerian and exhibit a high degree of spin-orbit coupling, which often requires the use of specialized numerical methods to model the system. First, we conducted a benchmarking and sensitivity study to identify the best simulation codes for future DART-supported studies and to understand how small perturbations in the initial conditions can affect the resulting dynamical evolution of the system. Then, we demonstrated that Dimorphos can enter a wide range of post-impact spin states, including possible chaotic non-principal axis rotation, depending on its shape and the amount of momentum transferred by the DART impact. We then explored the implications of an excited spin state, including the possibility of ongoing granular motion on Dimorphos’s surface resulting from the orbital perturbation induced by the DART impact. This thesis is focused predominantly on the dynamics of the Didymos binary. However, there are many other binary systems among the near-Earth asteroid population with similar physical and dynamical properties, making the results presented here relevant to the NEA binary population in general

Cometary Astrometry

Modern techniques for making cometary astrometric observations, reducing these observations, using accurate reference star catalogs, and computing precise orbits and ephemerides are discussed in detail and recommendations and suggestions are given in each area

The new Mars: The discoveries of Mariner 9

The Mariner 9 encounter with Mars is extensively documented with photographs taken by the satellite's onboard cameras, and an attempt is made to explain the observed Martian topography in terms of what is known about the geomorphological evolution of the earth. Early conceptions about the Mars surface are compared with more recent data made available by the Mariner 9 cameras. Other features of the planet Mars which are specifically discussed include the volcanic regions, the surface channels, the polar caps and layered terrain, the Martian atmosphere, and the planet's two moons--Phobos and Deimos

IAU Symposium 160

Some of the topics considered include: Search Programs, Populations of Small Bodies, Dynamics, Physical Observations and Modeling, Observations from Space, Origin and Evolution, and Data Bases.Sponsored by International Astronomical Union.Organized by Osservatorio Astronomico di Torino and the Lunar and Planetary Institute.With the contribution of Regione Piemonte, Provincia di Novara, A.P.T. Lago Maggiore, Consiglio Nazionale delle Ricerche, European Space Agency, Alenia Spazio S.p.A.; with the participation of Banca Popolare di Novara, Camera di Commercio di Novara, Martini & Rossi IVLAS S.p.A.PARTIAL CONTENTS: SMACS: Small Missions to Asteroids and Comets. A Fast, Low Cost Approach to the Space Reconnaissance of Near-Earth Objects / M.J.S. Belton--Stochasticity of Comet P/GE-Wang / D. Benest and R. Gonczi--Chips Off of 4 Vesta: A Newly Confirmed Asteroid Family and Link to Basaltic Achondrite Meteorites / R.P. Binzel--Asteroid 243 IDA as a Member of the Koronis Family: Predictions and Implications for the Galileo Encounter / R.P. Binzel and S.M. Slivan--Photoelectric Observations of 4179 Toutatis / C. Blanco and D. Riccioli--Observations of OH in P/Swift-TuttIe and in Several Recent Weak Comets with the Nancay Radio Telescope / D. Bockehie-Morvan, G. Bourgois, P. Colom, J. Crovisier, E. Gerard, and L. Jorda--The Origin of the 3.2-3.6 Micron Emission Features in Comets: Gas or Dust / D. Bockelee-Morvan, T.Y. Brooke, and J. Crovisier--Observations of Sub-millimeter Lines of CH30H, HCN and H2CO in Comet P/Swift-Tuttle with the James Clerk Maxwell Telescope / D. Bockelee-Morvan, R. Padman, J.K. Davies, and J. Crovisier--Astrometric Measurements of Minor Planets in 1991-1992 / G. Bocsa and M. Birlan--Concerted Elemental Analyses- PIXE and TOF-SIMS- of Interplanetary Dust Particles / J. Bohsung, E.K. Jessberger, and T. Stephan--Dynamical Effects of Asymmetric Nongravitational Forces on Long-Period Comets / A. Bolalto, G. Carballo, and J.A. Fenuindez--Images of Comet Swift-Tuttle 1992t in the Light of H20+ and CO+ Ions, and Dust / T. Bonev, K. Jockers, and G.P. Chernova--Two Components in Meteor Spectra / J. Borovicka

NASA thesaurus. Volume 3: Definitions

Publication of NASA Thesaurus definitions began with Supplement 1 to the 1985 NASA Thesaurus. The definitions given here represent the complete file of over 3,200 definitions, complimented by nearly 1,000 use references. Definitions of more common or general scientific terms are given a NASA slant if one exists. Certain terms are not defined as a matter of policy: common names, chemical elements, specific models of computers, and nontechnical terms. The NASA Thesaurus predates by a number of years the systematic effort to define terms, therefore not all Thesaurus terms have been defined. Nevertheless, definitions of older terms are continually being added. The following data are provided for each entry: term in uppercase/lowercase form, definition, source, and year the term (not the definition) was added to the NASA Thesaurus. The NASA History Office is the authority for capitalization in satellite and spacecraft names. Definitions with no source given were constructed by lexicographers at the NASA Scientific and Technical Information (STI) Facility who rely on the following sources for their information: experts in the field, literature searches from the NASA STI database, and specialized references

Searching for transits in the WTS with the difference imaging light curves

The search for exo-planets is currently one of the most exiting and active topics in astronomy. Small and rocky planets are particularly the subject of intense research, since if they are suitably located from their host star, they may be warm and potentially habitable worlds. On the other hand, the discovery of giant planets in short-period orbits provides important constraints on models that describe planet formation and orbital migration theories. Several projects are dedicated to discover and characterize planets outside of our solar system. Among them, the Wide-Field Camera Transit Survey (WTS) is a pioneer program aimed to search for extra-solar planets, that stands out for its particular aims and methodology. The WTS has been in operation since August 2007 with observations from the United Kingdom Infrared Telescope, and represents the first survey that searches for transiting planets in the near-infrared wavelengths; hence the WTS is designed to discover planets around M-dwarfs. The survey was originally assigned about 200 nights, observing four fields that were selected seasonally (RA = 03, 07, 17 and 19h) during a year. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. For the most complete field (19h-1145 epochs) in the survey, we produce an alternative set of light curves by using the method of difference imaging, which is a photometric technique that has shown important advantages when used in crowded fields. A quantitative comparison between the photometric precision achieved with both methods is carried out in this work. We remove systematic effects using the sysrem algorithm, scale the error bars on the light curves, and perform a comparison of the corrected light curves. The results show that the aperture photometry light curves provide slightly better precision for objects with J < 16. However, difference photometry light curves present a significant improvement for fainter stars. In order to detect transits in the WTS light curves, we use a modified version of the box-fitting algorithm. The implementation on the detection algorithm performs a trapezoid-fit to the folded light curve. We show that the new fit is able to produce more accurate results than the box-fit model. We describe a set of selection criteria to search for transit candidates that include a parameter calculated by our detection algorithm: the V-shape parameter, which has proven to be useful to automatically identify and remove eclipsing binaries from the survey. The criteria are optimized using Monte-Carlo simulations of artificial transit signals that are injected into the real WTS light curves and subsequently analyzed by our detection algorithm. We separately optimize the selection criteria for two different sets of light curves, one for F-G-K stars, and another for M-dwarfs. In order to search for transiting planet candidates, the optimized selection criteria are applied to the aperture photometry and difference imaging light curves. In this way, the best 200 transit candidates from a sample of ~ 475 000 sources are automatically selected. A visual inspection of the folded light curves of these detections is carried out to eliminate clear false-positives or false-detections. Subsequently, several analysis steps are performed on the 18 best detections, which allow us to classify these objects as transiting planet and eclipsing binary candidates. We report one planet candidate orbiting a late G-type star, which is proposed for photometric follow-up. The independent analysis on the M-dwarf sample provides no planet candidates around these stars. Therefore, the null detection hypothesis and upper limits on the occurrence rate of giant planets around M-dwarfs with J < 17 mag presented in a prior study are confirmed. In this work, we extended the search for transiting planets to stars with J < 18 mag, which enables us to impose a more strict upper limit of 1.1 % on the occurrence rate of short-period giant planets around M-dwarfs, which is significantly lower than other limit published so far. The lack of Hot Jupiters around M-dwarfs play an important role in the existing theories of planet formation and orbital migration of exo-planets around low-mass stars. The dearth of gas-giant planets in short-period orbit detections around M stars indicates that it is not necessary to invoke the disk instability formation mechanism, coupled with an orbital migration process to explain the presence of such planets around low-mass stars. The much reduced efficiency of the core-accretion model to form Jupiters around cool stars seems to be in agreement with the current null result. However, our upper limit value, the lowest reported sofar, is still higher than the detection rates of short-period gas-giant planets around hotter stars. Therefore, we cannot yet reach any firm conclusion about Jovian planet formation models around low-mass and cool main-sequence stars, since there are currently not sufficient observational evidences to support the argument that Hot Jupiters are less common around M-dwarfs than around Sun-like stars. The way to improve this situation is to monitor larger samples of M-stars. For example, an extended analysis of the remaining three WTS fields and currently running M-dwarf transit surveys (like Pan-Planets and PTF/M-dwarfs projects, which are monitoring up to 100 000 objects) may reduce this upper limit. Current and future space missions like Kepler and GAIA could also help to either set stricter upper limits or finally detect Hot Jupiters around low-mass stars. In the last part of this thesis, we present other applications of the difference imaging light curves. We report the detection of five faint extremely-short-period eclipsing binary systems with periods shorter than 0.23 d, as well as two candidates and one confirmed M-dwarf/M-dwarf eclipsing binaries. The etections and results presented in this work demonstrate the benefits of using the difference imaging light curves, especially when going to fainter magnitudes.Die Suche nach Exoplaneten ist heute eine der interessantesten und aktivsten Forschungsgebiete in der Astronomie. Vor allem erdähnliche Planeten sind das Ziel diverser Forschungsprojekte, da diese, sofern sie in einem bestimmten Abstand um ihrem Mutter-Stern kreisen, eine Oberflächentemperatur aufweisen, die ein Vorkommen von Wasser in flüssiger Form ermöglicht und somit ``habitabel'' sind. Außerdem sorgt die Entdeckung von Gasriesen in kurzperiodischen Umlaufbahnen für wichtige Erkenntnisse zu Modellen, die die Planetenbildung und orbitale Migration beschreiben. Viele Projekte haben es sich zum Ziel gesetzt, Planeten außerhalb unseres Sonnensystems zu finden und zu charakterisieren. Eines dieser Projekte is der WFCam Transit Survey (WTS), ein Pionierprogramm, das sich durch eine besondere Zielsetzung und Methodik auszeichnet. Die Beobachtungen für WTS haben im August 2007 am United Kingdom Infrared Telescope in Hawaii begonnen. Der Survey unternimmt die erste Suche nach Exoplaneten im nah-infraroten Wellenlängenbereich, welcher für die Suche nach Planeten um M-Zwerge optimal ist. Ursprünglich waren für das Projekt etwa 200 Nächte geplant - verteilt auf insgesamt vier Felder, welche über das Jahr verteilt beobachtet wurden. Die gewonnen Daten werden in einer automatischen Pipeline prozessiert, um Lichtkurven mit Aperturphotometrie zu erstellen. Für das Feld mit den meisten Beobachtungen (``19h-Feld'' mit 1145 Belichtungen)erzeugen wir ein alternatives Set an Lichtkurven mit ``difference imaging'', einer photometrische Methode, die sich in der Vergangenheit für Felder mit hohen Sterndichten als überlegen herausgestellt hat. Ein quantitativer Vergleich zwischen der photometrischen Genauigkeit der beiden Methoden wurde in dieser Arbeit durchgeführt. Wir korrigieren ausserdem systematische Effekte unter Verwendung des ``sysrem'' Algorithmus, skalieren die unrealistischen Fehlerbalken in den Lichtkurven und vergleichen diese mit den ursprünglichen. Die Ergebnisse zeigen, dass die Lichtkurven der Aperturphotometrie geringfügig höhere Genauigkeit für Objekte mit J < 16 mag aufweisen. Difference imaging Lichtkurven zeigen dagegen eine deutliche Verbesserung für schwächere Sterne. Um Transits von Planeten zu detektieren, verwenden wir eine modifizierte Version des ``box-fitting'' Algorithmus. Unsere Implementierung erweitert den Algorithmus um einem Trapezoid-Fit des Transitbereichs in der gefalteten Lichtkurve. Wie wir zeigen, liefert dieser Fit bessere Resultate als der reine Box-Fit. Wir beschreiben ein Set von Selektionskriterien, mit welchem wir nach Transit-Kandidaten in den Lichtkurven suchen. Diese Kriterien beinhalten einen Parameter, der von unserem Detektionsalgorithmus berechnet wird: der V -Form Parameter. Dieser hat sich als sehr nützlich herausgestellt, um automatisch bedeckungsveränderliche Doppelsterne zu identifizieren und diese von der Suche nach Planeten auszuschliessen. Wir optimieren die Kriterien über Monte-Carlo Simulationen von künstlichen Transitsignalen, welche in die realen WTS Lichtkurven eingespeist und durch unseren Detektionsalgorithmus analysiert werden. Wir führen die Optimierung der Selektionskriterien separat für zwei getrennte Sets von Lichtkurven durch, jeweils eines für F-G-K Sterne und für M-Sterne. Um nach Transits von Planeten zu suchen, werden die optimierten Kriterien auf die Lichtkurven von Aperturphotometrie und difference imaging Photometrie angewendet. Auf diese Weise werden die 200 besten Transitkandidaten aus ~475 000 Quellen automatisch selektiert. Danach wird eine visuelle Untersuchung der gefalteten Lichtkurven vorgenommen, um klare Fehldetektionen zu entfernen. Anschließend werden weitere Analyseschritte für die vielversprechendsten 18 Kandidaten durchgeführt, was es uns ermöglicht, diese Objekte als Planeten-Kandidaten oder bedeckungsveränderliche Doppelsterne zu klassifizieren. Wir haben einen vielversprechenden Planetenkandidaten gefunden, der um einen späten G-Stern kreist, für welchen wir eine photometrische Nachbeobachtung vorschlagen. Die davon unabhängige Analyse der M-Stern Lichtkurven führte zu keiner Detektion. Damit können wir die Nullhypothese und die oberen Limits für die Häufigkeit von Gasriesen um M-Zwerge mit J < 17 mag aus einer früheren Studie bestätigen. In dieser Arbeit erweitern wir die Suche nach Planetentransits auf Sterne mit J < 18 mag, was es uns ermöglicht, ein Limit von 1.1 % für die Häufigkeit von kurzperiodischen Gasreisen um M-Zwerge zu setzen, was deutlich niedriger ist als die Limits anderer Publikationen. Der Mangel an Hot Jupiters um M-Zwerge spielt eine wichtige Rolle für die Theorien von Planetenentstehung von Exoplaneten um Sterne mit niedriger Masse. Das Fehlen von Gasriesen in kurzperiodischen Orbits um M-Sterne zeigt, dass der Disk-Instabilitätsmechanismus in Kombination mit einer Migration des Orbits nicht benötigt wird,um die Planetenbildung zu beschreiben. Die deutlich geringere Effizienz des ``Core Accretion'' Modells, Jupiter um kühle Sterne zu erzeugen, wird durch die Nullhypothese bestätigt. Unser oberes Limit ist jedoch immer noch höher als die Detektionsraten von kurzperiodigen Gasriesen um heißere Sterne. Wir können also keinen abschließendes Fazit über die Entstehungsmodelle von jupiterähnlichen Planeten um kühle, massearme Hauptreihensterne ziehen. Momentan gibt es noch nicht ausreichende Beobachtungen, um die Vorhersage, dass Hot Jupiters weniger häufig um M-Sterne als um sonnenähnliche Sterne sind, zu untermauern. Um dies zu erreichen, muss eine noch grössere Anzahl an M-Sternen beobachtet werden. Dies könnte durch eine umfassende Analyse aller vier WTS Felder erreicht werden oder aber durch andere momentan durchgeführte M-Zwerg Transit Surveys wie etwa Pan-Planets oder PTF/M-Dwarfs, welche nahezu 100 000 M-Sterne beobachten. Aktuelle und zukünftige Weltraummissionen wie Kepler und GAIA könnten ebenfalls weitere Erkenntnise über die Häufigkeit von Hot Jupiters um massearme Sterne liefern. Im letzten Teil dieser Arbeit präsentieren wir weitere Anwendungen der difference imaging Lichtkurven. Wir haben insgesamt fünf lichtschwache, bedeckungsveränderliche Doppelsternsysteme mit extrem kurzen Perioden unterhalb von 0.23 Tagen detektiert. Ausserdem konnten wir zwei weitere unbestätigte und ein bestätigtes bedeckungsveränderliches M-Zwerg/M-Zwerg Doppelstern-System finden. Alle in dieser Arbeit präsentierten Detektionen demonstrieren die Stärken der difference imaging Methode, welche vor allem bei lichtschwächeren Magnituden entscheidende Vorteile bringt