The Universe in Motion, Book 2. Guidebook. The University of Illinois Astronomy Program.

ERIC Educational Resources Information Center

Atkin, J. Myron; Wyatt, Stanley P., Jr.

Presented is book two in a series of six books in the University of Illinois Astronomy Program which introduces astronomy to upper elementary and junior high school students. This guidebook is concerned with how celestial bodies move in space and how these motions are observed by astronomers. Topics discussed include: a study of the daily motion…

Numerical analysis of seismic events distributions on the planetary scale and celestial bodies astrometrical parameters

NASA Astrophysics Data System (ADS)

Bulatova, Dr.

2012-04-01

Modern research in the domains of Earth sciences is developing from the descriptions of each individual natural phenomena to the systematic complex research in interdisciplinary areas. For studies of its kind in the form numerical analysis of three-dimensional (3D) systems, the author proposes space-time Technology (STT), based on a Ptolemaic geocentric system, consist of two modules, each with its own coordinate system: (1) - 3D model of a Earth, the coordinates of which provides databases of the Earth's events (here seismic), and (2) - a compact model of the relative motion of celestial bodies in space - time on Earth known as the "Method of a moving source" (MDS), which was developed in MDS (Bulatova, 1998-2000) for the 3D space. Module (2) was developed as a continuation of the geocentric Ptolemaic system of the world, built on the astronomical parameters heavenly bodies. Based on the aggregation data of Space and Earth Sciences, systematization, and cooperative analysis, this is an attempt to establish a cause-effect relationship between the position of celestial bodies (Moon, Sun) and Earth's seismic events.

Method for deploying multiple spacecraft

NASA Technical Reports Server (NTRS)

Sharer, Peter J. (Inventor)

2007-01-01

A method for deploying multiple spacecraft is disclosed. The method can be used in a situation where a first celestial body is being orbited by a second celestial body. The spacecraft are loaded onto a single spaceship that contains the multiple spacecraft and the spacecraft is launched from the second celestial body towards a third celestial body. The spacecraft are separated from each other while in route to the third celestial body. Each of the spacecraft is then subjected to the gravitational field of the third celestial body and each of the spacecraft assumes a different, independent orbit about the first celestial body. In those situations where the spacecraft are launched from Earth, the Sun can act as the first celestial body, the Earth can act as the second celestial body and the Moon can act as the third celestial body.

Students' development of astronomy concepts across time

NASA Astrophysics Data System (ADS)

Plummer, Julia Diane

2006-02-01

The National Science Education Standards (NRC, 1996) recommend that students understand the apparent patterns of motion of the sun, moon and stars visible by the end of early elementary school. However, little information exists on students' knowledge of apparent celestial motion or instruction in this area. The goals of this dissertation were to describe children's knowledge of apparent celestial motion across elementary and middle school, explore early elementary students' ability to learn these topics through planetarium instruction, and begin the development of a learning progression for these concepts, First, third, and eighth grade students (N=60) were interviewed using a planetarium-like setting that allowed the students to demonstrate their ideas both verbally and with their own motions on an artificial sky. Analysis of these interviews suggests that students are not making the types of observations of the sky necessary to learn apparent celestial motion and any instruction they may have received has not helped them reach an accurate understanding of most topics. Most students at each grade level could not accurately describe the patterns of motion. Though the older students were more accurate in most of their descriptions than the younger students, in several areas the eighth grade students showed no improvement over the third grade students. The use of kinesthetic learning techniques in a planetarium program was also explored as a method to improve understanding of celestial motion. Pre- and post-interviews were conducted with participants from seven classes of first and second grade students (N=63). Students showed significant improvement in all areas of apparent celestial motion covered by the planetarium program and surpassed the middle school students' understanding of these concepts in most areas. This suggests that students in early elementary school are capable of learning the accurate description of apparent celestial motion. The results demonstrate the value of both kinesthetic learning techniques and the rich visual environment of the planetarium for improved understanding of celestial motion. Based on the results of these studies, I developed a learning progression describing how children may progress through successively more complex ways of understanding apparent celestial motion across elementary grades.

Global geometry of non-planar 3-body motions

NASA Astrophysics Data System (ADS)

Salehani, Mahdi Khajeh

2011-12-01

The aim of this paper is to study the global geometry of non-planar 3-body motions in the realms of equivariant Differential Geometry and Geometric Mechanics. This work was intended as an attempt at bringing together these two areas, in which geometric methods play the major role, in the study of the 3-body problem. It is shown that the Euler equations of a three-body system with non-planar motion introduce non-holonomic constraints into the Lagrangian formulation of mechanics. Applying the method of undetermined Lagrange multipliers to study the dynamics of three-body motions reduced to the level of moduli space {bar{M}} subject to the non-holonomic constraints yields the generalized Euler-Lagrange equations of non-planar three-body motions in {bar{M}} . As an application of the derived dynamical equations in the level of {bar{M}} , we completely settle the question posed by A. Wintner in his book [The analytical foundations of Celestial Mechanics, Sections 394-396, 435 and 436. Princeton University Press (1941)] on classifying the constant inclination solutions of the three-body problem.

Crash test for the Copenhagen problem.

PubMed

Nagler, Jan

2004-06-01

The Copenhagen problem is a simple model in celestial mechanics. It serves to investigate the behavior of a small body under the gravitational influence of two equally heavy primary bodies. We present a partition of orbits into classes of various kinds of regular motion, chaotic motion, escape and crash. Collisions of the small body onto one of the primaries turn out to be unexpectedly frequent, and their probability displays a scale-free dependence on the size of the primaries. The analysis reveals a high degree of complexity so that long term prediction may become a formidable task. Moreover, we link the results to chaotic scattering theory and the theory of leaking Hamiltonian systems.

Where Are We?

ERIC Educational Resources Information Center

Waiveris, Charles; Craine, Timothy V.

1996-01-01

Discusses a simple procedure for determining our exact location on Earth based on the motion of celestial bodies and latitude and longitude. This hands-on activity requires students to design and construct an apparatus that will produce accurate measurements. The materials required are a knitting needle, a tape measure, and a sunny day. (AIM)

Rotation of the Earth, Mars and asteroids: components, techniques and data quality

NASA Astrophysics Data System (ADS)

Souchay, Jean

2004-12-01

We explain in some detail the analytical formulations which enable to modelize both the free and the forced motion of any celestial body taken as rigid or deformable, and we show how they have been applied (with the corresponding level of precision) for the Earth, Mars and the asteroids in general

G-DYN Multibody Dynamics Engine

NASA Technical Reports Server (NTRS)

Acikmese, Behcet; Blackmore, James C.; Broderick, Daniel

2011-01-01

G-DYN is a multi-body dynamic simulation software engine that automatically assembles and integrates equations of motion for arbitrarily connected multibody dynamic systems. The algorithm behind G-DYN is based on a primal-dual formulation of the dynamics that captures the position and velocity vectors (primal variables) of each body and the interaction forces (dual variables) between bodies, which are particularly useful for control and estimation analysis and synthesis. It also takes full advantage of the spare matrix structure resulting from the system dynamics to numerically integrate the equations of motion efficiently. Furthermore, the dynamic model for each body can easily be replaced without re-deriving the overall equations of motion, and the assembly of the equations of motion is done automatically. G-DYN proved an essential software tool in the simulation of spacecraft systems used for small celestial body surface sampling, specifically in simulating touch-and-go (TAG) maneuvers of a robotic sampling system from a comet and asteroid. It is used extensively in validating mission concepts for small body sample return, such as Comet Odyssey and Galahad New Frontiers proposals.

Comparison and Historical Evolution of Ancient Greek Cosmological Ideas and Mathematical Models

NASA Astrophysics Data System (ADS)

Pinotsis, Antonios D.

2005-12-01

We present a comparative study of the cosmological ideas and mathematical models in ancient Greece. We show that the heliocentric system introduced by Aristarchus of Samos was the outcome of much intellectual activity. Many Greek philosophers, mathematicians and astronomers such as Anaximander, Philolaus, Hicetas, Ecphantus and Heraclides of Pontus contributed to this. Also, Ptolemy was influenced by the cosmological model of Heraclides of Pontus for the explanation of the apparent motions of Mercury and Venus. Apollonius, who wrote the definitive work on conic sections, introduced the theory of eccentric circles and implemented them together with epicycles instead of considering that the celestial bodies travel in elliptic orbits. This is due to the deeply rooted belief that the orbits of the celestial bodies were normal circular motions around the Earth, which was still. There was also a variety of important ideas which are relevant to modern science. We present the ideas of Plato that are consistent with modern relativity theories, as well as Aristarchus' estimations of the size of the Universe in comparison with the size of the planetary system. As a first approximation, Hipparchus' theory of eccentric circles was equivalent to the first two laws of Kepler. The significance of the principle of independence and superposition of motions in the formulation of ancient cosmological models is also clarified.

Spectroscopy - so what?

NASA Astrophysics Data System (ADS)

Stanley, Matthew

2010-07-01

The development of astronomical spectroscopy allowed amazing achievements in investigating the composition and motion of celestial bodies. But even beyond specific measurements and results, the fruitfulness and practice of spectroscopy had important ramifications on a more abstract level. This paper will discuss ways in which spectroscopy inspired or boosted new theories of the atom, life, and the Universe; redrew the boundaries among scientific disciplines; demonstrated the unity of terrestrial and celestial physical laws; changed what counted as scientific knowledge; and even revealed divine mysteries. Scientists and science writers from the first half-century of astronomical spectroscopy will be discussed, including James Clerk Maxwell, William Crookes, John Tyndall, Agnes Clerke, William Huggins and Norman Lockyer.

Spectroscopy - so what?

NASA Astrophysics Data System (ADS)

Stanley, Matthew

2010-01-01

The development of astronomical spectroscopy allowed amazing achievements in investigating the composition and motion of celestial bodies. But even beyond specific measurements and results, the fruitfulness and practice of spectroscopy had important ramifications on a more abstract level. This paper will discuss ways in which spectroscopy inspired or boosted new theories of the atom, life, and the universe; redrew the boundaries among scientific disciplines; demonstrated the unity of terrestrial and celestial physical laws; changed what counted as scientific knowledge; and even revealed divine mysteries. Scientists and science writers from the first half-century of astronomical spectroscopy will be discussed, including James Clerk Maxwell, William Thomson (Lord Kelvin), John Tyndall, Agnes Clerke, William Huggins, and Norman Lockyer.

Students' Development of Astronomy Concepts across Time

NASA Astrophysics Data System (ADS)

Plummer, Julia

Students in Grades 1, 3, and 8 (N = 60) were interviewed while using a planetarium-like setting that allowed the students to demonstrate their ideas about apparent celestial motion both verbally and with their own motions. Though the older students were generally more accurate in many conceptual areas compared with the younger students, in several areas, the eighth-grade students showed no improvement over the third-grade students. The use of kinesthetic learning techniques in a planetarium program was also explored as a method to improve understanding of celestial motion. Pre- and postinterviews were conducted with participants from seven classes of first- and second-grade students (N = 63). Students showed significant improvement in all areas of apparent celestial motion covered by the planetarium program and surpassed the middle school students' understanding of these concepts in most areas. Based on the results of these studies, a learning progression was developed describing how children may progress through successively more complex ways of understanding apparent celestial motion across elementary grades.

Popular Astronomy

NASA Astrophysics Data System (ADS)

Newcomb, Simon

2011-10-01

Preface; Part I. The System of the World Historically Developed: Introduction; 1. The ancient astronomy, or the apparent motions of the heavenly bodies; 2. The Copernican system, or the true motions of the heavenly bodies; 3. Universal gravitation; Part II. Practical Astronomy: Introductory remarks; 1. The telescope; 2. Application of the telescope to celestial measurements; 3. Measuring distances in the heavens; 4. The motion of light; 5. The spectroscope; Part III. The Solar System: 1. General structure of the solar system; 2. The sun; 3. The inner group of planets; 4. The outer group of planets; 5. Comets and meteors; Part IV. The Stellar Universe: 1. The stars as they are seen; 2. The structure of the universe; 3. The cosmogony; Addendum to Part III chapter 2; Appendix; Index; Addendum II, the satellites of Mars; Explanation of the star maps.

An Efficient Method for Studying the Stability and Dynamics of the Rotational Motions of Celestial Bodies

NASA Astrophysics Data System (ADS)

Pavlov, A. I.; Maciejewski, A. J.

2003-08-01

We use the alternative MEGNO (Mean Exponential Growth of Nearby Orbits) technique developed by Cincotta and Simo to study the stability of orbital-rotational motions for plane oscillations and three-dimensional rotations. We present a detailed numerical-analytical study of a rigid body in the case where the proper rotation of the body is synchronized with its orbital motion as 3: 2 (Mercurian-type synchronism). For plane rotations, the loss of stability of the periodic solution that corresponds to a 3: 2 resonance is shown to be soft, which should be taken into account to estimate the upper limit for the ellipticity of Mercury. In studying stable and chaotic translational-rotational motions, we point out that the MEGNO criterion can be effectively used. This criterion gives a clear picture of the resonant structures and allows the calculations to be conveniently presented in the form of the corresponding MEGNO stability maps for multidimensional systems. We developed an appropriate software package.

Orbital motion (3rd revised and enlarged edition)

NASA Astrophysics Data System (ADS)

Roy, A. E.

The fundamental principles of celestial mechanics are discussed in an introduction for students of astronomy, aerospace engineering, and geography. Chapters are devoted to the dynamic structure of the universe, coordinate and timekeeping systems, the reduction of observational data, the two-body problem, the many-body problem, general and special perturbations, and the stability and evolution of the solar system. Consideration is given to lunar theory, artificial satellites, rocket dynamics and transfer orbits, interplanetary and lunar trajectories, orbit determination and interplanetary navigation, binaries and other few-body systems, and many-body systems of stars. Diagrams, graphs, tables, and problems with solutions are provided.

Children Learning to Explain Daily Celestial Motion: Understanding Astronomy across Moving Frames of Reference

ERIC Educational Resources Information Center

Plummer, Julia D.; Wasko, Kyle D.; Slagle, Cynthia

2011-01-01

This study investigated elementary students' explanations for the daily patterns of apparent motion of the Sun, Moon, and stars. Third-grade students were chosen for this study because this age level is at the lower end of when many US standards documents suggest students should learn to use the Earth's rotation to explain daily celestial motion.…

Microarsecond models for the celestial motions of the CIP and CEO

NASA Astrophysics Data System (ADS)

Capitaine, N.

2004-09-01

The Celestial intermediate pole (CIP) and Celestial ephemeris (orintermediate) origin (CEO/CIO) have been adopted by the IAU (c.f. IAU2000 Resolution B1.8) as the celestial pole and origin, respectively,to be used for realizing the intermediate celestial system between theInternational Terrestrial System (ITRS) and Geocentric CelestialReference System (GCRS). Resolution B1.8 has also recommended that theInternational Earth Rotation and Reference Systems Service (IERS)continue to provide users with data and algorithms for the conventionaltransformation. The IAU 2000 Resolutions have been implemented in theIERS 2003 Conventions including Tables and routines that provide thecelestial motions of the CIP and the CEO with a theoretical accuracy ofone microarcsecond after one century using either the classical or thenew transformation. This paper reports on the method used for achievingthis accuracy in the positions of the CIP and CIO and on the differencebetween this rigorous procedure and the pre-2003 classical one.

Frontiers in Relativistic Celestial Mechanics, Vol. 2, Applications and Experiments

NASA Astrophysics Data System (ADS)

Kopeikin, Sergei

2014-08-01

Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This second volume of a two-volume series covers applications of the theory as well as experimental verifications. From tools to determine light travel times in curved space-time to laser ranging between earth and moon and between satellites, and impacts on the definition of time scales and clock comparison techniques, a variety of effects is discussed. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: J. Simon, A. Fienga: Victor Brumberg and the French school of analytical celestial mechanics T. Fukushima: Elliptic functions and elliptic integrals for celestial mechanics and dynamical astronomy P. Teyssandier: New tools for determining the light travel time in static, spherically symmetric spacetimes beyond the order G2 J. Müller, L. Biskupek, F. Hofmann and E. Mai: Lunar laser ranging and relativity N. Wex: Testing relativistic celestial mechanics with radio pulsars I. Ciufolini et al.: Dragging of inertial frames, fundamental physics, and satellite laser ranging G. Petit, P. Wolf, P. Delva: Atomic time, clocks, and clock comparisons in relativistic spacetime: a review

Stars and Seasons in Southern Africa

NASA Astrophysics Data System (ADS)

Snedegar, K. V.

Although the indigenous people of Southern Africa traditionally viewed the sky as a place quite apart from the Earth, they believed celestial phenomena to be natural signs united with those of the Earth in a harmonious synchronicity. There is no substantial evidence that the precolonial Africans imagined a casual relationship between celestial bodies and the seasonal patterns of life on Earth. They did, however, recognize a coincidental relationship. The traditional African cosmos, then, worked as a noetic principle unifying the observed motions of celestial bodies, the sequence of seasons, and the behavior of plants and animals. Such a cosmos, with local peculiarities, was widely understood in Southern Africa before the end of the last century. By the early 20th century European colonial paradigms had largely obliterated this African worldview. This paper will offer a partial reconstruction. Pre-colonial South African people viewed time as a sequence of discrete natural events; through annual repetition these events served as a guide for proper human action. The South Africans analyzed the passage of time in terms of the motions of celestial bodies, the maturation of beneficial plants, and the mating patterns of animals. The rightful course of human life was seen to fit within the seasonal context of these natural phenomena. The visibility of conspicuous stars and asterisms marked significant times of year. For instance, the Lovedu people greeted the dawn rising of Canopus with joy: "The boy has come out." The star was a signal for rainmaking and boys' initiation ceremonies to proceed. The Venda constellation Thutlwa, the giraffes, comprises α and β Crucis and α and β Centauri. In October Thutlwa skims the trees of the evening horizon. The Venda Thutlwa literally means 'rising above the trees,' an allusion to the majestic vegetarian creatures and the stars advising the people to be done with their spring planting. This paper will describe stellar associations with other creatures: wild dogs, warthogs, wildebeests, swallows, cuckoos and cicadas. In each case the visibility of a star will synchronize with a behavior of the associated species. Together, stars and species informed man of the order and unity of an African cosmos — a worldview that must have been as satisfying as it was beautiful.

Inquiry and Astronomy: Preservice Teachers' Investigations of Celestial Motion

ERIC Educational Resources Information Center

Plummer, Julia D.; Zahm, Valerie M.; Rice, Rebecca

2010-01-01

This study investigated the impact of an open inquiry experience on elementary science methods students' understanding of celestial motion as well as the methods developed by students to answer their own research questions. Pre/post interviews and assessments were used to measure change in participants' understanding (N = 18). A qualitative…

A Study of Planetarium Effectiveness on Student Achievement, Perceptions and Retention.

ERIC Educational Resources Information Center

Ridky, Robert William

Reported is a study to determine the effect of planetarium instruction in terms of immediate attainment, attitude, and retention in the teaching of selected celestial motion and non-celestial motion concepts, when contrasted to or combined with the inquiry activities utilized by the nationally developed science curricula. Observations were made on…

Qualitative and quantitative behaviour of planetary systems; Proceedings of the 3rd Alexander von Humboldt Colloquium on Celestial Mechanics, Ramsau, Austria, Mar. 29-Apr. 4, 1992

NASA Astrophysics Data System (ADS)

Dvorak, R.; Henrard, J.

1993-06-01

Topics addressed include planetary theories, the Sitnikov problem, asteroids, resonance, general dynamical systems, and chaos and stability. Particular attention is given to recent progress in the theory and application of symplectic integrators, a computer-aided analysis of the Sitnikov problem, the chaotic behavior of trajectories for the asteroidal resonances, and the resonant motion in the restricted three-body problem. Also discussed are the second order long-period motion of Hyperion, meteorites from the asteroid 6 Hebe, and least squares parameter estimation in chaotic differential equations.

USSR and Eastern Europe Scienitific Abstracts, Geophysics, Astronomy and Space. Number 399

DTIC Science & Technology

1977-06-10

Orbit 47 TASS Announces Launching of "Molniya-3" Communications Satellite 47 Abstracts of Scientific Articles 49 Inhomogeneities of Electron...Directions in Space Technology 52 Motion of Body of Variable Rest Mass in Gravity Field 52 Orbits in Applied Problems of Celestial Mechanics..... 53...Satellite Oscillations in Plane of Elliptical Orbit 53 Submillimeter Radiation of Convective Cloud Systems 54 Combined Braking of Spacecraft in

Gravitational mechanism of active life of the Earth, planets and satellites

NASA Astrophysics Data System (ADS)

Barkin, Yury

2010-05-01

From positions of geodynamic model of the forced gravitational swing, wobble and displacements of shells of a planet are studied and fundamental problems of geodynamics, geology, geophysics, planetary sciences are solved etc.: 1) The mechanism of cyclic variations of activity of natural processes in various time scales. 2) The power of endogenous activity of planetary natural processes on planets and satellites. 3) The phenomenon of polar inversion of natural processes on planets and satellites. 4) Spasmodic and catastrophic changes of activity of natural processes. 5) The phenomenon of twisting of hemispheres (latitude zones or belts) of celestial bodies. 6) Formation of the pear-shaped form of celestial bodies and the mechanism of its change. 7) The ordered planetary structures of geological formations. 8) The phenomena of bipolarity of celestial bodies and antipodality of geology formations. Mechanism. The fundamental feature of a structure of celestial bodies is their shell structure. The most investigated is the internal structure of the Earth. For the Moon and wide set of other bodies of solar system models of an internal structure have been constructed on the basis of the data of observations obtained at studying of their gravitational fields as a result of realization of the appropriate space missions. The basic components for the majority of celestial bodies are the core, the mantle and the crust. To other shells we concern atmospheres (for example, at Venus, Mars, the Titan etc.) and oceanic shells (the Titan, the Earth, Enceladus etc.). Shells are the complex (composite) formations. Planets and satellites are not spherical celestial bodies. The centers of mass of shells of the given planet (or the satellite) and their appropriate principal axes of inertia do not coincide. Accordingly, all their shells are characterized by the certain dynamic oblatenesses. Differences of dynamical oblatenesses results in various forced influences of external celestial bodies on shells of the given body. Dynamical oblatenesses of shells, thus, characterize the endogenous activity of a planet by external celestial bodies. Other important factor of endogenous activity of a planet is a eccentric position of the centers of mass of the shells (for example, of the core and the mantle). The eccentricity of the shells is inherited during geological evolution of a planet as system of shells (Barkin, 2002). Consequences of exitation of the Earth system. The new tides (Barkin, 2005) are caused by relative displacements of the core and mantle. These displacements are reflected in variations of many natural processes due to gravitational action of the core. The displacing core causes deformations of all layers of viscous-elastic mantle. In the given work from more general positions the mechanisms of excitation of a system of shells of the Earth under action of a gravitational attraction of the Sun, the Moon and planets, the phenomena of their relative swings, translational displacements and turns relatively from each other, and the wide list geodynamical consequences of the specified excitation of the Earth are studied. At once we shall emphasize, that the developed geodynamic model has allowed to carry out the important dynamic researches of displacements of shells of the Earth, their deformations and changes, and variations of its natural processes and for the first time to explain the nature of such fundamental phenomena and processes in geodynamics, geology and geophysics as: cyclicity of natural processes and its mechanism; power of processes in various time scales; unity of cyclic processes and universality of their frequency bases; synchronism of geodynamic, geophysical, biophysical and social events; inversion, contrast and opposite directed changes of activity of natural processes in opposite hemispheres of the Earth; step-by-step variations of natural processes, sawtooth course of activity of natural processes in various time scales; orderliness in an distribution of geological formations on the Earth, planets and satellites; existence of antipodal formations on planets and satellites; the phenomenon of twisting of hemispheres of bodies of solar system, twisting of layers and latitudinal zones of shells of celestial bodies including inner layers and shells, etc. All the specified phenomena from the resulted list to some extent are discussed in the given work and illustrated on the basis of modern researches in Earth's sciences and the researches executed by means of space missions. In a complex, the executed researches have shown universality of discussed mechanisms and their important role in dynamics and geoevolution of planets and satellites in other planetary systems, and also stars and pulsars with the systems of planets (Barkin, 2009). Cyclicity. The excitation on the part of external celestial bodies of the system core-mantle depends from relative positions of external celestial bodies, from particularities of their perturbed orbital motions and from rotary motion of the planet. The specified motions have a cyclic nature which is shown in various time scales. Hence, and excitation of shells and their layers will have also cyclic character and to be shown in various time scales. Hence, cyclic variations of all planetary natural processes in all the variety widely should be observed, as takes place in reality. The periods of variations are characterized by extremely wide range - from hours up to tens and hundreds millions years. If the core makes slow secular drift relatively to the mantle all layers and shells of the Earth test secular deformation, thermodynamic and other changes. The cavity of the core and its flows are changed slowly that results in secular variations of a magnetic field (Barkin, 2002, 2009). Inversion and asymmetry of cyclic and secular variations of natural processes. The essence of it rather wide distributed phenomena is, that activity of natural processes varies in an antiphase in opposite hemispheres of the Earth (first of all in northern and southern hemispheres). Told concerns to all geodynamic and geophysical processes, to variations of physical fields, to tectonic and geodetic reorganizations of layers of the Earth, to redistributions of atmospheric, oceanic and other fluid masses of the Earth. The certain asymmetry of displays of processes in northern and southern hemispheres on the other hand is marked. So secular trends of some processes are contrast in northern and southern hemispheres, i.e. velocities of secular changes are essentially different. All described phenomena are caused first of all by cyclic oscillations and secular drift of the core to the north (in present epoch). In longer time scales the similar phenomena of inversion, dissymmetry also have place and determine a nature and style of displacements of continents and lithospheric plates, planetary magmatic activity and plume tectonics as a whole, formation of mountains, elevations and depressions, systems of lineaments and cracks, regressions and transgressions of sea level (Barkin, 2002). Synchronous steps of activity of natural processes. 'For an explanation of observably step-by-step variations of geodynamic and geophysical processes the mechanism of sharp sporadic relative displacements of the core and the mantle and deformations of the mantle in the certain periods of time (the phenomenon of "galloping of the core') is offered.

Relativistic Navigation: A Theoretical Foundation

NASA Technical Reports Server (NTRS)

Turyshev, Slava G.

1996-01-01

We present a theoretical foundation for relativistic astronomical measurements in curved space-time. In particular, we discuss a new iterative approach for describing the dynamics of an isolated astronomical N-body system in metric theories of gravity. To do this, we generalize the Fock-Chandrasekhar method of the weak-field and slow-motion approximation (WFSMA) and develop a theory of relativistic reference frames (RF's) for a gravitationally bounded many-extended-body problem. In any proper RF constructed in the immediate vicinity of an arbitrary body, the N-body solutions of the gravitational field equations are formally presented as a sum of the Riemann-flat inertial space-time, the gravitational field generated by the body itself, the unperturbed solutions for each body in the system transformed to the coordinates of this proper RF, and the gravitational interaction term. We develop the basic concept of a general WFSMA theory of the celestial RF's applicable to a wide class of metric theories of gravity and an arbitrary model of matter distribution. We apply the proposed method to general relativity. Celestial bodies are described using a perfect fluid model; as such, they possess any number of internal mass and current multipole moments that explicitly characterize their internal structures. The obtained relativistic corrections to the geodetic equations of motion arise because of a coupling of the bodies' multiple moments to the surrounding gravitational field. The resulting relativistic transformations between the different RF's extend the Poincare group to the motion of deformable self-gravitating bodies. Within the present accuracy of astronomical measurements we discuss the properties of the Fermi-normal-like proper RF that is defined in the immediate vicinity of the extended compact bodies. We further generalize the proposed approximation method and include two Eddington parameters (gamma, Beta). This generalized approach was used to derive the relativistic equations of satellite motion in the vicinity of the extended bodies. Anticipating improvements in radio and laser tracking technologies over the next few decades, we apply this method to spacecraft orbit determination. We emphasize the number of feasible relativistic gravity tests that may be performed within the context of the parameterized WFSMA. Based on the planeto-centric equations of motion of a spacecraft around the planet, we suggested a new null test of the Strong Equivalence Principle (SEP). The experiment to measure the corresponding SEP violation effect could be performed with the future Mercury Orbiter mission. We discuss other relativistic effects, including the perihelion advance and the redshift and geodetic precession of the orbiter's orbital plane about Mercury, as well as the possible future implementation of the proposed formalism in software codes developed for solar-system orbit determination. All the important calculations are completely documented, and the references contain an extensive list of cited literature.

Research of small bodies motion prognosis effectivity on cluster "Skif Cyberia". (Russian Title: Исследование эффективности прогнозирования движения малых тел Солнечной системы на кластере "Skif Cyberia")

NASA Astrophysics Data System (ADS)

Baturin, A. P.

2010-12-01

The results of the experimental estimations on cluster "Skif Cyberia" of Everhart's numerical integration accuracy and rapidness are presented. The integration has been carried out for celestial bodies' equations of motion such as N-body problem equations and perturbed two-body problem equations. In the last case the perturbing bodies' coordinates are being taked during calculations from the ephemeris DE406. The accuracy and rapidness estimations have been made by means of forward and backward integrations with various values of Everhart method parameters of motion equations of the short-periodic comet Herschel-Rigollet. The optimal combinations of these parameters have been obtained. The research has been made both for 16-digit decimal accuracy and for 34-digit one.

Building a Learning Progression for Celestial Motion: An Exploration of Students' Reasoning about the Seasons

ERIC Educational Resources Information Center

Plummer, Julia D.; Maynard, L.

2014-01-01

We present the development of a construct map addressing the reason for the seasons, as a subset of a larger learning progression on celestial motion. Five classes of 8th grade students (N?=?38) participated in a 10-day curriculum on the seasons. We revised a hypothetical seasons construct map using a Rasch model analysis of students'…

Position determination systems. [using orbital antenna scan of celestial bodies

NASA Technical Reports Server (NTRS)

Shores, P. W. (Inventor)

1976-01-01

A system for an orbital antenna, operated at a synchronous altitude, to scan an area of a celestial body is disclosed. The antenna means comprises modules which are operated by a steering signal in a repetitive function for providing a scanning beam over the area. The scanning covers the entire area in a pattern and the azimuth of the scanning beam is transmitted to a control station on the celestial body simultaneous with signals from an activated ground beacon on the celestial body. The azimuth of the control station relative to the antenna is known and the location of the ground beacon is readily determined from the azimuth determinations.

Celestial Object Imaging Model and Parameter Optimization for an Optical Navigation Sensor Based on the Well Capacity Adjusting Scheme.

PubMed

Wang, Hao; Jiang, Jie; Zhang, Guangjun

2017-04-21

The simultaneous extraction of optical navigation measurements from a target celestial body and star images is essential for autonomous optical navigation. Generally, a single optical navigation sensor cannot simultaneously image the target celestial body and stars well-exposed because their irradiance difference is generally large. Multi-sensor integration or complex image processing algorithms are commonly utilized to solve the said problem. This study analyzes and demonstrates the feasibility of simultaneously imaging the target celestial body and stars well-exposed within a single exposure through a single field of view (FOV) optical navigation sensor using the well capacity adjusting (WCA) scheme. First, the irradiance characteristics of the celestial body are analyzed. Then, the celestial body edge model and star spot imaging model are established when the WCA scheme is applied. Furthermore, the effect of exposure parameters on the accuracy of star centroiding and edge extraction is analyzed using the proposed model. Optimal exposure parameters are also derived by conducting Monte Carlo simulation to obtain the best performance of the navigation sensor. Finally, laboratorial and night sky experiments are performed to validate the correctness of the proposed model and optimal exposure parameters.

Celestial Object Imaging Model and Parameter Optimization for an Optical Navigation Sensor Based on the Well Capacity Adjusting Scheme

PubMed Central

Wang, Hao; Jiang, Jie; Zhang, Guangjun

2017-01-01

The simultaneous extraction of optical navigation measurements from a target celestial body and star images is essential for autonomous optical navigation. Generally, a single optical navigation sensor cannot simultaneously image the target celestial body and stars well-exposed because their irradiance difference is generally large. Multi-sensor integration or complex image processing algorithms are commonly utilized to solve the said problem. This study analyzes and demonstrates the feasibility of simultaneously imaging the target celestial body and stars well-exposed within a single exposure through a single field of view (FOV) optical navigation sensor using the well capacity adjusting (WCA) scheme. First, the irradiance characteristics of the celestial body are analyzed. Then, the celestial body edge model and star spot imaging model are established when the WCA scheme is applied. Furthermore, the effect of exposure parameters on the accuracy of star centroiding and edge extraction is analyzed using the proposed model. Optimal exposure parameters are also derived by conducting Monte Carlo simulation to obtain the best performance of the navigation sensor. Finally, laboratorial and night sky experiments are performed to validate the correctness of the proposed model and optimal exposure parameters. PMID:28430132

Simultaneous calibrations of Voyager celestial and inertial attitude control systems in flight

NASA Technical Reports Server (NTRS)

Jahanshahi, M. H.

1982-01-01

A mathematical description of the data reduction technique used to simultaneously calibrate the Voyager celestial and inertial attitude control subsystems is given. It is shown that knowledge of the spacecraft limit cycle motion, as measured by the celestial and the inertial sensors, is adequate to result in the estimates of a selected number of errors which adversely affect the spacecraft attitude knowledge.

Contemplation and Calculation: The Universe Discovered.

ERIC Educational Resources Information Center

Solovyov, Yury

1992-01-01

Discusses how early notions about celestial mechanics were restructured, one by one, involving the following concepts: the celestial sphere and its rotation; the spherical earth; planetary motion; and models for the solar system initiated by Eudoxus, Hipparchus, Ptolemy, and Copernicus. (JJK)

Relation between the celestial reference system and the terrestrial reference system of a rigid earth

NASA Astrophysics Data System (ADS)

Aoki, Shinko

The equations of motion for a rigid earth under the influence of the sun and moon are solved analytically up to the second-order perturbation, and the results are used to elucidate the relationship between the celestial and terrestrial reference systems. The derivations are given in detail, and consideration is given to celestial-ephemeris and instantaneous-rotation poles, wobble, the departure point as the origin of the local inertial system, the precession-nutation matrix, and techniques for improving the celestial reference system.

Power Beaming, Orbital Debris Removal, and Other Space Applications of a Ground Based Free Electron Laser

DTIC Science & Technology

2010-03-01

mask of strength, his character, fortitude, and xxii devotion to our family helped to keep me on my feet. What I say with words, he says through...superfluid) and an extremely large heat capacity. This large heat capacity is what makes He II an ideal refrigerant for high power and high frequency...limited tools, ancient astronomers accomplished many insightful discoveries regarding the motion of celestial bodies, but prior to the 1600s, most of

Celestial mechanics with geometric algebra

NASA Technical Reports Server (NTRS)

Hestenes, D.

1983-01-01

Geometric algebra is introduced as a general tool for Celestial Mechanics. A general method for handling finite rotations and rotational kinematics is presented. The constants of Kepler motion are derived and manipulated in a new way. A new spinor formulation of perturbation theory is developed.

Using record player demonstrations as analog models for geophysical fluids

NASA Astrophysics Data System (ADS)

Grannan, A. M.; Cheng, J. S.; Hawkins, E. K.; Ribeiro, A.; Aurnou, J. M.

2015-12-01

All celestial bodies, including stars, planets, satellites, and asteroids, rotate. The influence of rotation on the fluid layers in these bodies plays an important and diverse role, affecting many processes including oceanic and atmospheric circulation at the surface and magnetic field generation occurring in the interior. To better understand these large-scale processes, record players and containers of water are used as analog models to demonstrate the basic interplay between rotation and fluid motions. To contrast between rotating and non-rotating fluid motions, coffee creamer and food coloring are used as fluid tracers to provide a hands-on method of understanding the influence of rotation on the shapes of the planets, weather patterns, and the alignment of magnetic fields with rotational axes. Such simple demonstrations have been successfully employed for children in public outreach events and for adults in graduate level fluid dynamics courses.

Viscoelastic tides: models for use in Celestial Mechanics

NASA Astrophysics Data System (ADS)

Ragazzo, C.; Ruiz, L. S.

2017-05-01

This paper contains equations for the motion of linear viscoelastic bodies interacting under gravity. The equations are fully three dimensional and allow for the integration of the spin, the orbit, and the deformation of each body. The goal is to present good models for the tidal forces that take into account the possibly different rheology of each body. The equations are obtained within a finite dimension Lagrangian framework with dissipation function. The main contribution is a procedure to associate to each spring-dashpot model, which defines the rheology of a body, a potential and a dissipation function for the body deformation variables. The theory is applied to the Earth (solid part plus oceans) and a comparison between model and observation of the following quantities is made: norm of the Love numbers, rate of tidal energy dissipation, Chandler period, and Earth-Moon distance increase.

Opportunities of Teaching Archaeoastronomy in Thailand

ERIC Educational Resources Information Center

Anantasook, Sakanan; Yuenyong, Chokchai; Coll, Richard K.

2015-01-01

Ancient cultures around the world systematically observed the sky and noticed the motions of celestial objects including the stars, Moon, Sun, and planets. Many structural symbolic patterns were built to perceive, visualize and understand the celestial phenomena. They have used this knowledge, archaeoastronomy, to survive, and as bases for…

Theoretical astrophysics in the 19th century (Homage to Radó von Kövesligethy)

NASA Astrophysics Data System (ADS)

Balázs, Lajos G.

The nature of astronomical information is determined mostly by the incoming light. Theoretical astrophysics means basically the theory of light emission and its relation to the physical constitution of the emitting celestial bodies. The necessary physical disciplines include theory of gravitation, theory of radiation, thermodynamics, matter--radiation interaction. The most significant theoretical achievement in the 17th - 18th century was the axiomatic foundation of mechanics and the law of gravitation. In the context of the nature of light, there were two conceptions: Newton contra Huygens, i.e. particle versus wave phenomenon. Using the theory of gravitation, first speculations appeared on black holes (Michell, Laplace), cosmogony (Kant-Laplace theory), the structure of the Milky Way (Kant), and the explanation of motion of the celestial bodies. The Olbers Paradox, formulated in the 19th century, is still one of the most significant constraints on observational cosmology. The development of thermodynamics, matter-radiation interaction, development of the theory of electromagnetism became important milestones. Maxwell's theory was the classical framework of the interaction between matter and radiation. Kirchhoff and Bunsen's revolutionary discovery of spectral analysis (1859) showed that observation of spectra makes it possible to study the chemical composition of emitting bodies. Thermodynamics predicted the existence of the black body radiation. It did not succeed, however, to determine the functional form of the wavelength dependence. A combination of the thermodynamic equation of state with the equation of hydrostatics resulted in the first stellar models (Lane, Ritter, Schuster). The first successful spectral equation of black body radiation was the theory of continuous spectra of celestial bodies by Radó von Kövesligethy (published 1885 in Hungarian, 1890 in German). Kövesligethy made several assumptions on the matter-radiation interaction: radiating matter consists of interacting particles, the form of interaction is an inverse power law, the radiation field is represented by the aether, aether is made also from interacting particles, light is the propagation of the oscillation of the aether particles, there is an equipartition between the oscillations energy of material and aetheric particles. Based on these assumptions, he derived a spectral equation with the following properties: the spectral distribution of radiation depends only on the temperature, the total irradiated energy is finite (15 years before Planck!), the wavelength of the intensity maximum is inversely proportional to the temperature (eight years before Wien!). Using his spectral equation, he estimated the temperature of several celestial bodies, including the Sun.

On the Analysis of Multistep-Out-of-Grid Method for Celestial Mechanics Tasks

NASA Astrophysics Data System (ADS)

Olifer, L.; Choliy, V.

2016-09-01

Occasionally, there is a necessity in high-accurate prediction of celestial body trajectory. The most common way to do that is to solve Kepler's equation analytically or to use Runge-Kutta or Adams integrators to solve equation of motion numerically. For low-orbit satellites, there is a critical need in accounting geopotential and another forces which influence motion. As the result, the right side of equation of motion becomes much bigger, and classical integrators will not be quite effective. On the other hand, there is a multistep-out-of-grid (MOG) method which combines Runge-Kutta and Adams methods. The MOG method is based on using m on-grid values of the solution and n × m off-grid derivative estimations. Such method could provide stable integrators of maximum possible order, O (hm+mn+n-1). The main subject of this research was to implement and analyze the MOG method for solving satellite equation of motion with taking into account Earth geopotential model (ex. EGM2008 (Pavlis at al., 2008)) and with possibility to add other perturbations such as atmospheric drag or solar radiation pressure. Simulations were made for satellites on low orbit and with various eccentricities (from 0.1 to 0.9). Results of the MOG integrator were compared with results of Runge-Kutta and Adams integrators. It was shown that the MOG method has better accuracy than classical ones of the same order and less right-hand value estimations when is working on high orders. That gives it some advantage over "classical" methods.

The Mathematics of Go to Telescopes

ERIC Educational Resources Information Center

Teets, Donald

2007-01-01

This article presents the mathematics involved in finding and tracking celestial objects with an electronically controlled telescope. The essential idea in solving this problem is to choose several different coordinate systems that simplify the various motions of the earth and other celestial objects. These coordinate systems are then related by…

High-precision numerical integration of equations in dynamics

NASA Astrophysics Data System (ADS)

Alesova, I. M.; Babadzanjanz, L. K.; Pototskaya, I. Yu.; Pupysheva, Yu. Yu.; Saakyan, A. T.

2018-05-01

An important requirement for the process of solving differential equations in Dynamics, such as the equations of the motion of celestial bodies and, in particular, the motion of cosmic robotic systems is high accuracy at large time intervals. One of effective tools for obtaining such solutions is the Taylor series method. In this connection, we note that it is very advantageous to reduce the given equations of Dynamics to systems with polynomial (in unknowns) right-hand sides. This allows us to obtain effective algorithms for finding the Taylor coefficients, a priori error estimates at each step of integration, and an optimal choice of the order of the approximation used. In the paper, these questions are discussed and appropriate algorithms are considered.

About mechanisms of tetonic activity of the satellites

NASA Astrophysics Data System (ADS)

Barkin, Yu. V.

2003-04-01

ABOUT MECHANISMS OF TECTONIC ACTIVITY OF THE SATELLITES Yu.V. Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Due to attraction of the central planet and others external bodies satellite is subjected by tidal and non-tidal deformations. Elastic energy is changed in dependence from mutual position and motion of celestial bodies and as result the tensional state of satellite and its tectonic (endogenous) activity also is changed. Satellites of the planets have the definite shell’s structure and due to own rotation these shells are characterized by different oblatenesses. Gravitational interaction of the satellite and its mother planet generates big additional mechanical forces (and moments) between the neighboring non-spherical shells of the satellite (mantle, core and crust). These forces and moments are cyclic functions of time, which are changed in the different time-scales. They generate corresponding cyclic perturbations of the tensional state of the shells, their deformations, small relative transnational displacements and slow rotation of the shells and others. In geological period of time it leads to a fundamental tectonic reconstruction of the body. Definite contribution to discussed phenomena are caused by classical tidal mechanism. of planet-satellite interaction. But in this report we discuss in first the new mechanisms of endogenous activity of celestial bodies. They are connected with differential gravitational attraction of non-spherical satellite shells by the external celestial bodies which leads: 1) to small relative rotation (nutations) of the shells; 2) to small relative translational motions of the shells (displacements of their center of mass); 3) to relative displacements and rotations of the shells due to eccentricity of their center of mass positions; 4) to viscous elastic deformations of the shells and oth. (Barkin, 2001). For higher evaluations of the power of satellite endogenous activities were obtained analytical formulae. Obtained theoretical evaluations of the force and power characteristics are in good agreement with observational date and in particular they explain some from the well known problems of planetology. The following phenomena obtain an explanation: 1. Higher endogenous activity of Io; 2. Europe crack systems; 3. high endogenous activity of Ganimede, Titan, Miranda, Enceladus, Ariel. Well known relations of tectonic activity between satellites: Ariel and Umbriel, Reiha and Diona, Titania and Oberon have been explained in terms of numerical values of force and energy characteristics. Conclusion about high endogenous activity of Titan also presents important interest. The work was accepted and financed by RFBR grant N 02-05-64176 and by grant SAB2000-0235 of Ministry of Education of Spain (Secretaria de Estado de Educacion y Universidades).

On Everhart Method

NASA Astrophysics Data System (ADS)

Pârv, Bazil

This paper deals with the Everhart numerical integration method, a well-known method in astronomical research. This method, a single-step one, is widely used for numerical integration of motion equation of celestial bodies. For an integration step, this method uses unequally-spaced substeps, defined by the roots of the so-called generating polynomial of Everhart's method. For this polynomial, this paper proposes and proves new recurrence formulae. The Maple computer algebra system was used to find and prove these formulae. Again, Maple seems to be well suited and easy to use in mathematical research.

Measured Correlated Motion of theThree Body Coulomb Interacting System H^+ + H^+ + H^-

NASA Astrophysics Data System (ADS)

Wiese, L. M.

1998-05-01

The problem of three bodies interacting through a 1/r potential is a fundamental problem of physics. While its longstanding fame stems from its application to celestial mechanics, in atomic physics its importance arises from application to Coulomb-interacting systems, in which all three bodies carry some net charge. Because the three bodies interact through long range Coulomb forces over their entire path, their motion can be highly correlated. The effect of the interaction among the three bodies and any resulting correlated motion is reflected in how the available energy is ultimately shared among the three particles. By experimentally determining the energy sharing in a three body system, we can gain insight into the interactions governing the system. For the three body Coulomb interacting system of H^+ + H^+ + H^-, we have measured the partitioning of available center of mass (c.m.) energy among the particles when the system is in a near collinear configuration. By colliding 4 keV H_3^+ with a He target gas cell, we produce the H^+ + H^+ + H^- system a few eV above the dissociative limit. All three fragments are laboratory energy and angle resolved. By detecting all three in triple coincidence, we determine unambiguously the final state dynamics for each triply coincident event. Transforming our results to the c.m. frame, we determine the partitioning of available energy among the three particles. We have modified the Dalitz plot of high energy physics to elucidate correlations in the motion of any three body atomic system. Correlated motion in the H^+ + H^+ + H^- system is indicated by a nonuniform distribution on the Dalitz plot. For the near collinear breakup of H_3^+, we have observed the H^- to reside anywhere between the two H^+, from the Coulomb saddle point to the near vicinity of a proton. This work is supported by NSF Grant Number 9419505.

Lunar Laser Ranging: Glorious Past And A Bright Future

NASA Astrophysics Data System (ADS)

Shelus, Peter J.

Lunar Laser Ranging (LLR), a part of the NASA Apollo program, has beenon-going for more than 30 years. It provides the grist for a multi-disciplinarydata analysis mill. Results exist for solid Earth sciences, geodesy and geodynamics,solar system ephemerides, terrestrial and celestial reference frames, lunar physics,general relativity and gravitational theory. Combined with other data, it treatsprecession of the Earth''s spin axis, lunar induced nutation, polar motion/Earthrotation, Earth orbit obliquity to the ecliptic, intersection of the celestial equatorwith the ecliptic, luni-solar solid body tides, lunar tidal deceleration, lunar physicaland free librations, structure of the moon and energy dissipation in the lunar interior.LLR provides input to lunar surface cartography and surveying, Earth station and lunar retroreflector location and motion, mass of the Earth-moon system, lunar and terrestrial gravity harmonics and Love numbers, relativistic geodesic precession, and the equivalence principle of general relativity. With the passive nature of the reflectors and steady improvement in observing equipment and data analysis, LLR continues to provide state-of-the-art results. Gains are steady as the data-base expands. After more than 30 years, LLR remains the only active Apollo experiment. It is important to recognize examples of efficient and cost effective progress of research. LLR is just such an example.

On the Origin of Rotation of a Celestial Body

NASA Astrophysics Data System (ADS)

Vujičić, V. A.

1988-03-01

The differential equations of the self-rotation of a celestial body have been evaluated. From an integral of these equations a formula for angular velocity of the celestial body was obtained. This formula after being applied to the rotation of the Sun and of the Earth gives, respectively, the following angular velocity ranges: 0.588×10-6<ω<18, 187×10-6 and 0.7533×10-5<ω<12,4266×10-5. These are up to three times narrower than those previously obtained by Savić and Kašanin [1].

Mechanisms of Earth activity forsed by external celestial bodies:energy budjet and nature of cyclicity

NASA Astrophysics Data System (ADS)

Barkin, Yu. V.; Ferrandiz, J. M.

2003-04-01

In given report we discuss tidal and non-tidal mechanisms of forced tectonic (endogenous) activity of the Earth caused by gravitational attraction of the Moon, Sun and the planets. On the base of the classical solution of the problem of elasticity for model of the Earth with concentric mass distribution the evaluations of the tidal energy and power of Earth lunar-solar deformations, including their joint effect, were obtained. Important role of the joint energetic effect of rotational deformation of the Earth with lunar and solar tides was illustrated. Gravitational interaction of the Moon and Sun with non-spherical, non-homogeneous shells of the Earth generates big additional mechanical forces and moments of the interaction of the neighboring shells (rigid core, liquid core, mantle, lithosphere and separate plates). Acting of these forces and moments in the different time scales on the corresponding sells generates cyclic perturbations of the tensional state of the shells, their deformations, small relative translational displacements and small relative rotational oscillations of the shells. In geological period of time it leads to a fundamental tectonic reconstruction of the Earth. These additional forces and moments of the cyclic celestial-mechanical nature produce cyclic deformations of the all layers of the body and organize and control practically all natural processes. The additional force between mantle and core is cyclic and characterized by the wide basis of frequencies typical for orbital motions (of the Sun, Moon and planets), for rotational motion of the Earth, Moon and Sun and for many from observed natural processes. The problem about small relative translatory-rotary motion of the two shells separated by the thin viscous-elastic layer is studied. The differential equations of motion were obtained and have been studied in particular cases (plane motion of system; case of two axisymmetrical interacting shells and oth.) by approximate methods of small parameter and methods of averaging. Some regimes of the relative translatory-rotary motions of the shells were described in analytical form. Wide set observed geodynamical and geophysical phenomena can be illustrated as results or as reflections of the small and slow relative displacements of the shells in corresponding time-scales. Barkin's work was accepted and financed by RFBR grant 02-05-64176 and by grant SAB2000-0235 of Ministry of Education of Spain (Secretaria de Estado de Educacion y Universidades).

Density variations of meteor flux along the Earth's orbit

NASA Technical Reports Server (NTRS)

Svetashkova, N. T.

1987-01-01

No model of distribution of meteor substance is known to explain the observed diurnal and annual variations of meteor rates, if that distribution is assumed to be constant during the year. Differences between the results of observations and the prediction of diurnal variation rates leads to the conclusion that the density of the orbits of meteor bodies changes with the motion of the Earth along its orbit. The distributions of the flux density over the celestial sphere are obtained by the method described previously by Svetashkova, 1984. The results indicate that the known seasonal and latitudinal variations of atmospheric conditions does not appear to significantly affect the value of the mean flux density of meteor bodies and the matter influx onto the Earth.

Solar oscillation time delay measurement assisted celestial navigation method

NASA Astrophysics Data System (ADS)

Ning, Xiaolin; Gui, Mingzhen; Zhang, Jie; Fang, Jiancheng; Liu, Gang

2017-05-01

Solar oscillation, which causes the sunlight intensity and spectrum frequency change, has been studied in great detail, both observationally and theoretically. In this paper, owing to the existence of solar oscillation, the time delay between the sunlight coming from the Sun directly and the sunlight reflected by the other celestial body such as the satellite of planet or asteroid can be obtained with two optical power meters. Because the solar oscillation time delay is determined by the relative positions of the spacecraft, reflective celestial body and the Sun, it can be adopted as the navigation measurement to estimate the spacecraft's position. The navigation accuracy of single solar oscillation time delay navigation system depends on the time delay measurement accuracy, and is influenced by the distance between spacecraft and reflective celestial body. In this paper, we combine it with the star angle measurement and propose a solar oscillation time delay measurement assisted celestial navigation method for deep space exploration. Since the measurement model of time delay is an implicit function, the Implicit Unscented Kalman Filter (IUKF) is applied. Simulations demonstrate the effectiveness and superiority of this method.

On transformation between international celestial and terrestrial reference systems

NASA Astrophysics Data System (ADS)

Bretagnon, P.; Brumberg, V. A.

2003-09-01

Based on the current IAU hierarchy of the relativistic reference systems, practical formulae for the transformation between barycentric (BCRS) and geocentric (GCRS) celestial reference systems are derived. BCRS is used to refer to ICRS, International Celestial Reference System. This transformation is given in four versions, dependent on the time arguments used for BCRS (TCB or TDB) and for GCRS (TCG or TT). All quantities involved in these formulae have been tabulated with the use of the VSOP theories (IMCCE theories of motion of the major planets). In particular, these formulae may be applied to account for the indirect relativistic third-body perturbations in motion of Earth's satellites and Earth's rotation problem. We propose to use the SMART theory (IMCCE theory of Earth's rotation) in constructing the Newtonian three-dimensional spatial rotation transformation between GCRS and ITRS, the International Terrestrial Reference System. This transformation is compared with two other versions involving extra angular variables currently used by IERS, the International Earth Rotation Service. It is shown that the comparison of these three forms of the same transformation may be greatly simplified by using the proposed composite rotation formula. Tables 1-20 of Appendix B containing the initial terms of the VSOP-based series for the BCRS<->GCRS transformation are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/408/387. The work on ICRS<->GCRS transformation with the use of VSOP theories was done in February-March 2002 during the stay of the second author in IMCCE. The authors hoped to complete the second part concerning GCRS<->ITRS transformation with the use of SMART theory in September 2002 during the visit of the first author to IAA. The grave disease of Pierre Bretagnon which tragically resulted in his death on November 17, 2002, did not permit us to complete this work. The aim to improve SMART theory by taking into account the indirect relativistic third-body perturbations as indicated in the paper also remains unachieved. The second author is publishing this paper in memoriam of

Protection of celestial environments and the law of outer space

NASA Astrophysics Data System (ADS)

Tennen, Leslie; Race, Margaret

The law of outer space expressly addresses the matter of preservation and protection of natural celestial environments from harmful contamination and disruption by mankind in the explo-ration and use of outer space, including the moon and other celestial bodies. The Outer Space Treaty, however, does not prohibit all human impact to an extraterrestrial environment, but rather permits a wide range of activities that could have significant environmental ramifications. This legal regime may be in conflict with the interests of preserving celestial environments for scientific research, especially when considered in relation to activities conducted for commercial purposes. Nevertheless, the Moon Agreement provides a mechanism by which special protective measures can be implemented to protect particular areas of the moon and other celestial bodies for scientific investigation. This paper examines the current status of the law of outer space vis-a-vis the protection and preservation of natural celestial environments. Particular emphasis is placed on the policies on which the legal obligations are based, together with consideration of the non-appropriation principle, and the commercial use of lunar and other celestial resources and areas. In addition, the concepts of international scientific preserves, special regions, keep out zones, and planetary parks are compared and evaluated as potential means to limit the disturbance to celestial environments caused by the activities of mankind.

Solar system lithograph set for earth and space science

NASA Technical Reports Server (NTRS)

1995-01-01

A color lithographs of many of the celestial bodies within our solar system are contained in this educational set of materials. Printed on the back of each lithograph is information regarding the particular celestial body. A sheet with information listing NASA resources and electronic resources for education is included.

Motion of the Jovian commensurability resonances and the character of the celestial mechanics in the asteroid zone - Implication for kinematics and structure

NASA Technical Reports Server (NTRS)

Torbett, M.; Smoluchowski, R.

1982-01-01

The motion of the Jovian commensurability resonances during the early evolution of the solar system induced by the dissipation of the accretion disk results in fundamental differences in the celestial mechanics of objects over which a resonance passes from that observed for a stationary resonance. Objects experiencing resonance passage acquire irreversible increases of average eccentricity to large values accounting for the present-day random velocities of the asteroids. Semi-major axes are similarly irreversibly decreased by amounts capable of clearing the Kirkwood gaps. The gap widths are in agreement with observation.

Did a Comet Deliver the Chelyabinsk Meteorite?

NASA Astrophysics Data System (ADS)

Gladysheva, O. G.

2017-09-01

An explosion of a celestial body occurred on the fifteenth of February, 2013, near Chelyabinsk (Russia). The explosive energy was determined as 500 kt of TNT, on the basis of which the mass of the bolide was estimated at 107 kg, and its diameter at 19 m [1]. Fragments of the meteorite, such as LL5/S4-WO type ordinary chondrite [2] with a total mass only of 2•103 kg, fell to the earth's surface [3]. Here, we will demonstrate that the deficit of the celestial body's mass can be explained by the arrival of the Chelyabinsk chondrite on Earth by a significantly more massive but fragile ice-bearing celestial body.

Elliptical Chandler pole motions of the Earth and Mars

NASA Astrophysics Data System (ADS)

Barkin, Yury; Ferrandiz, Jose

2010-05-01

In the work the values of the period and eccentricity of Chandler motion of poles of axes of rotation of the Earth and Mars have been determined. The research has been carried out on the basis of developed earlier by authors an intermediate rotary Chandler-Euler motion of the weakly deformable celestial bodies (Barkin, Ferrandiz and Getino, 1996; Barkin, 1998). An influence of a liquid core on Chandler motion of a pole in the given work has not considered. The periods of the specified pole motions make 447.1 d for the Earth and 218.1 d for Mars. In comparison with Euler motions of poles because of elastic properties of planets the Chandler periods are increased accordingly on 142.8 d (about 46.9 %) for the Earth and on 26.2 d (on 13.7 %) for Mars. Values of eccentricities of specified Chandler motions of pole e = √b2 --a2- b (here a both b are smaller and big semi-axes of Chandler ellipse) make 0.09884 for the Earth and 0.3688 for Mars (accordingly, on 21.1 % and 6.2 % more than the appropriate values of eccentricities for models of planets as rigid non-spherical bodies). Axes of an ellipse a also b correspond to the principal equatorial axes of inertia of a planet Ox and Oyfor which the moments of inertia have the smallest valueA and middle value B. The pole of the principal axis of inertia Ox for the Earth is displaced to the west on the angle 14°9285, and the pole of the principal axis of inertia Ox for Mars is displaced to the west on the angle 105°0178 (in the appropriate basic geographical systems of coordinates of the given planets). For ellipticties of Chandler trajectories ɛ = (b- a)-b the values 0.004897 (for the Earth) and 0.07048 (for Mars) have been obtained. The specified values surpass by Euler values of appropriate ellipticties on 46.8 % (in case of the Earth) and on 13.3 % (in the case of Mars). Love number k2describing the elastic properties of planets, were accepted equal 0.30 for the Earth and 0.153 for Mars. Estimations of Chandler periods will well be coordinated to similar estimations of other authors for models of elastic planet in 200-212 d (Konopliv et al., 2006; Zharkov, Gudkova, 2009). The values of eccentricity and ellipticity of Chandler pole motion of the Earth will be coordinated to earlier estimations e=0.096-0.098 and ɛ=0.0046-0.0048 (Barkin, 1998; Barkin, Ferrandiz, 2004), and for Mars have been obtained for the first time. The account of influence of a liquid core on considered parameters of motion of poles of planet with elastic mantle also is discussed in report on the base of author's approach developed in the paper (Ferrandiz, Barkin, 2001). The Barkin's work partially was finacially accepted by Spanish grants, Japanise-Russian grant N-09-02-92113-JF and by RFBR grant N 08-02-00367. References Barkin Yu.V., Ferrandiz J.M., J. Getino (1996) About Applications Angle-Action Variables in Rotation Dynamics of the Deformable Celestial Bodies. (Eds. S. Ferraz-Mello, B. Morrando, J.-E. Arlot) Dynamics, ephemerides and astrometry of the solar system. Proceedings. 172 nd Symposium of the International Astronomical Union, Paris ( France), 3-8 Jul. 1995. 1996, pp. 243-244. Barkin Yu.V. (1998) Unperturbed Chandler's Motion and Perturbation Theory of the Rotational Motion of the Deformable Celestial Bodies. Astronomical and Astrophysical Transactions, v. 17, N3, pp. 431-475. Barkin Yu.V., Ferrandiz J.M. (2004) Some dynamical effects in unperturbed and perturbed Earth rotation caused by elastic properties of the mantle. Journees 2004 'Systems de reference spatio temporals' (20-22 September, 2004, Paris, France). Fundamental Astronomy: New concepts and models for high accuracy observations. Book of abstracts, Observatoire de Paris, pp. 15-16. Ferrandiz, J.M. and Barkin, Yu.V. (2001) Dynamics of the rotational motion of the planet with the elastic mantle, liquid core and with the changeable external shell. Proceedings of International Conference «AstroKazan-2001». Astronomy and geodesy in new millennium (24-29 September 2001), Kazan State University: Publisher «DAS», pp. 123-129. Konopliv A.S., Yoder C.F., Standish E.M., Yuan D.-N. and Sjogren W.L. (2006) A global solution for Mars static and seasonal gravity, Mars orientation, Phobos and Deimos masses, and Mars ephemeris. Icarus, V. 182, pp. 23-50. Zarkov V.N., Gudkova T.V. (2009) The period and Q of the Chandler wobble of Mars. Planetary and Space Science (in press).

Expected Improvements in VLBI Measurements of the Earth's Orientation

NASA Technical Reports Server (NTRS)

Ma, Chopo

2003-01-01

Measurements of the Earth s orientation since the 1970s using space geodetic techniques have provided a continually expanding and improving data set for studies of the Earth s structure and the distribution of mass and angular momentum. The accuracy of current one-day measurements is better than 100 microarcsec for the motion of the pole with respect to the celestial and terrestrial reference frames and better than 3 microsec for the rotation around the pole. VLBI uniquely provides the three Earth orientation parameters (nutation and UTI) that relate the Earth to the extragalactic celestial reference frame. The accuracy and resolution of the VLBI Earth orientation time series can be expected to improve substantially in the near future because of refinements in the realization of the celestial reference frame, improved modeling of the troposphere and non-linear station motions, larger observing networks, optimized scheduling, deployment of disk-based Mark V recorders, full use of Mark IV capabilities, and e-VLBI. More radical future technical developments will be discussed.

On the co-existence of maximal and whiskered tori in the planetary three-body problem

NASA Astrophysics Data System (ADS)

Pinzari, Gabriella

2018-05-01

In this paper, we discuss about the possibility of the coexistence of stable and unstable quasi-periodic Kolmogorov-Arnold-Moser (kam) tori in a region of the phase space of the three-body problem. The argument of proof goes along kam theory and, especially, the production of two non-smoothly related systems of canonical coordinates in the same region of the phase space, the possibility of which is foreseen, for "properly degenerate" systems, by a theorem of Nekhoroshev and Miščenko and Fomenko. The two coordinate systems are alternative to the classical reduction of the nodes by Jacobi, described, e.g., in Arnold ["Small denominators and problems of stability of motion in classical and celestial mechanics," 18, 85-191 (1963)].

Determination of the observation conditions of celestial bodies with the aid of the DISPO system

NASA Technical Reports Server (NTRS)

Kazakov, R. K.; Krivov, A. V.

1984-01-01

The interactive system for determining the observation conditions of celestial bodies is described. A system of programs was created containing a part of the DISPO Display Interative System of Orbit Planning. The system was used for calculating the observatiion characteristics of Halley's comet during its approach to Earth in 1985-86.

A Gauge-generalized Solution for Non-Keplerian Motion in the Frenet-Serret Frame

NASA Astrophysics Data System (ADS)

Garber, Darren D.

2009-05-01

The customary modeling of perturbed planetary and spacecraft motion as a continuous sequence of unperturbed two-body orbits (instantaneous ellipses) is conveniently assigned a physical interpretation through the Keplerian and Delaunay elements and complemented mathematically by the Lagrange-type equations which describe the evolution of these variables. If however the actual motion is very non-Keplerian (i.e. the perturbed orbit varies greatly from a two-body orbit), then its modeling by a sequence of conics is not necessarily optimal in terms of its mathematical description and its resulting physical interpretation. Since, in principle a curve of any type can be represented as a sequence of points from a family of curves of any other type (Efroimsky 2005), alternate non-conic curves can be utilized to better describe the perturbed non-Keplerian motion of the body both mathematically and with a physically relevant interpretation. Non-Keplerian motion exists in both celestial mechanics and astrodynamics as evident by the complex interactions within star clusters and also as the result of a spacecraft accelerating via ion propulsion, solar sails and electro-dynamic tethers. For these cases, the sequence of simple orbits to describe the motion is not based on conics, but instead a family of spirals. The selection of spirals as the underlying simple motion is supported by the fact that it is unnecessary to describe the motion in terms of instantaneous orbits tangent to the actual trajectory (Efroimsky 2002, Newman & Efroimsky 2003) and at times there is an advantage to deviate from osculation, in order to greatly simplify the resulting mathematics via gauge freedom (Efroimsky & Goldreich 2003, Slabinski 2003, Gurfil 2004). From these two principles, (1) spirals as instantaneous orbits, and (2) controlled deviation from osculation, new planetary equations are derived for new non-osculating elements in the Frenet-Serret frame with the gauge function as a measure of non-osculation.

[The celestial phenomena in A. Dürer's engraving Melancholia I].

PubMed

Weitzel, Hans

2009-01-01

The celestial body of Dürer's engraving Melencolia I is connected with his painting of a meteor, the Raveningham-painting; it is shown that the origin of this painting owns to the impact of the meteor of Ensisheim in 1492. Until now the celestial body, the balance, and the magic square are nearly consistently interpreted as the planet Saturn, the zodiac sign Libra, and the planet Jupiter, and the melancholy woman is subject to these heavenly bodies. Consequently, neoplatonic astrology has been the main focus of the engraving; including the rainbow, the engraving has also been interpreted biblically. The present paper, however, places emphasis on problems of the geometry as the reason of melancholy. Any astronomical meaning of the configuration of the numbers of the magic square is discarded.

Neural coding underlying the cue preference for celestial orientation

PubMed Central

el Jundi, Basil; Warrant, Eric J.; Byrne, Marcus J.; Khaldy, Lana; Baird, Emily; Smolka, Jochen; Dacke, Marie

2015-01-01

Diurnal and nocturnal African dung beetles use celestial cues, such as the sun, the moon, and the polarization pattern, to roll dung balls along straight paths across the savanna. Although nocturnal beetles move in the same manner through the same environment as their diurnal relatives, they do so when light conditions are at least 1 million-fold dimmer. Here, we show, for the first time to our knowledge, that the celestial cue preference differs between nocturnal and diurnal beetles in a manner that reflects their contrasting visual ecologies. We also demonstrate how these cue preferences are reflected in the activity of compass neurons in the brain. At night, polarized skylight is the dominant orientation cue for nocturnal beetles. However, if we coerce them to roll during the day, they instead use a celestial body (the sun) as their primary orientation cue. Diurnal beetles, however, persist in using a celestial body for their compass, day or night. Compass neurons in the central complex of diurnal beetles are tuned only to the sun, whereas the same neurons in the nocturnal species switch exclusively to polarized light at lunar light intensities. Thus, these neurons encode the preferences for particular celestial cues and alter their weighting according to ambient light conditions. This flexible encoding of celestial cue preferences relative to the prevailing visual scenery provides a simple, yet effective, mechanism for enabling visual orientation at any light intensity. PMID:26305929

Neural coding underlying the cue preference for celestial orientation.

PubMed

el Jundi, Basil; Warrant, Eric J; Byrne, Marcus J; Khaldy, Lana; Baird, Emily; Smolka, Jochen; Dacke, Marie

2015-09-08

Diurnal and nocturnal African dung beetles use celestial cues, such as the sun, the moon, and the polarization pattern, to roll dung balls along straight paths across the savanna. Although nocturnal beetles move in the same manner through the same environment as their diurnal relatives, they do so when light conditions are at least 1 million-fold dimmer. Here, we show, for the first time to our knowledge, that the celestial cue preference differs between nocturnal and diurnal beetles in a manner that reflects their contrasting visual ecologies. We also demonstrate how these cue preferences are reflected in the activity of compass neurons in the brain. At night, polarized skylight is the dominant orientation cue for nocturnal beetles. However, if we coerce them to roll during the day, they instead use a celestial body (the sun) as their primary orientation cue. Diurnal beetles, however, persist in using a celestial body for their compass, day or night. Compass neurons in the central complex of diurnal beetles are tuned only to the sun, whereas the same neurons in the nocturnal species switch exclusively to polarized light at lunar light intensities. Thus, these neurons encode the preferences for particular celestial cues and alter their weighting according to ambient light conditions. This flexible encoding of celestial cue preferences relative to the prevailing visual scenery provides a simple, yet effective, mechanism for enabling visual orientation at any light intensity.

The significance of the Sun, Moon and celestial bodies to societies in the Carpathian basin during the Bronze Age

NASA Astrophysics Data System (ADS)

Pásztor, Emília

2011-06-01

Celestial events often exerted a great or even decisive influence on the life of ancient communities. They may provide some of the foundations on which an understanding of the deeper meaning of mythologies, religious systems and even folk tales can be based. These influences are reflected and may be detected in the archaeological material as well. There is good evidence that celestial (especially solar and perhaps lunar) phenomena played a particularly important rôle in the worldview of prehistoric Europe. To reveal the social and ideational significance of concepts relating to the celestial bodies in the prehistory of the Carpathian Basin, complex investigations on orientations of houses and graves, prestige archaeological finds and iconography have been accomplished. The results indicate ideological and/or social changes, which developed into a likely organized ideological system in large part of Central Europe including the Carpathian Basin by the Late Bronze Age. It might also be the first period in prehistory when people became really interested in celestial phenomena.

Free polar motion of a triaxial and elastic body in Hamiltonian formalism: Application to the Earth and Mars

NASA Astrophysics Data System (ADS)

Folgueira, M.; Souchay, J.

2005-03-01

The purpose of this paper is to show how to solve in Hamiltonian formalism the equations of the polar motion of any arbitrarily shaped elastic celestial body, i.e. the motion of its rotation axis (or angular momentum) with respect to its figure axis. With this aim, we deduce from canonical equations related to the rotational Hamiltonian of the body, the analytical solution for its free polar motion which depends both on the elasticity and on its moments of inertia. In particular, we study the influence of the phase angle δ, responsible for the dissipation, on the damping of the polar motion. In order to validate our analytical equations, we show that, to first order, they are in complete agreement with those obtained from the classical Liouville equations. Then we adapt our calculations to the real data obtained from the polar motion of the Earth (polhody). For that purpose, we characterize precisely the differences in radius J-χ and in angle l-θ between the polar coordinates (χ,θ) and (J,l) representing respectively the motion of the axis of rotation of the Earth and the motion of its angular momentum axis, with respect to an Earth-fixed reference frame, after showing the influence of the choice of the origin on these coordinates, and on the determination of the Chandler period as well. Then we show that the phase lag δ responsible for the damping for the selected time interval, between Feb. 1982 and Apr. 1990, might be of the order of δ ≈ 6 °, according to a numerical integration starting from our analytical equations. Moreover, we emphasize the presence in our calculations for both χ and θ, of an oscillation with a period TChandler/2, due to the triaxial shape of our planet, and generally not taken into account. In a last step, we apply our analytical formulation to the polar motion of Mars, thus showing the high dependence of its damping on the poorly known value of its Love number k. Moreover we emphasize the large oscillations of Mars' polar motion due to the triaxiality of this planet.

OPTICAL SPECTRA OF CANDIDATE SOUTHERN HEMISPHERE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Jauncey, D. L.; Johnston, H. M.

2011-11-15

We present the results of spectroscopic observations of the optical counterparts of 47 southern radio sources from the candidate International Celestial Reference Catalogue as part of a very long baseline interferometry (VLBI) program to strengthen the celestial reference frame, especially in the south. We made the observations with the 3.58 m European Southern Observatory New Technology Telescope. We obtained redshifts for 30 quasars and one radio galaxy, with a further seven objects being probable BL Lac objects with featureless spectra. Of the remainder, four were clear misidentifications with Galactic stars and five had low signal-to-noise spectra and could not bemore » classified. These results, in combination with new VLBI data of the radio sources with redshifts more than 2, add significantly to the existing data needed to refine the distribution of source proper motions over the celestial sphere.« less

Celestial Navigation

ERIC Educational Resources Information Center

Rosenkrantz, Kurt

2005-01-01

In the unit described in this article, students discover the main principles of navigation, build tools to observe celestial bodies, and apply their new skills to finding their position on Earth. Along the way students see how science, mathematics, technology, and history are intertwined.

Inclined asymmetric librations in exterior resonances

NASA Astrophysics Data System (ADS)

Voyatzis, G.; Tsiganis, K.; Antoniadou, K. I.

2018-04-01

Librational motion in Celestial Mechanics is generally associated with the existence of stable resonant configurations and signified by the existence of stable periodic solutions and oscillation of critical (resonant) angles. When such an oscillation takes place around a value different than 0 or π , the libration is called asymmetric. In the context of the planar circular restricted three-body problem, asymmetric librations have been identified for the exterior mean motion resonances (MMRs) 1:2, 1:3, etc., as well as for co-orbital motion (1:1). In exterior MMRs the massless body is the outer one. In this paper, we study asymmetric librations in the three-dimensional space. We employ the computational approach of Markellos (Mon Not R Astron Soc 184:273-281, https://doi.org/10.1093/mnras/184.2.273, 1978) and compute families of asymmetric periodic orbits and their stability. Stable asymmetric periodic orbits are surrounded in phase space by domains of initial conditions which correspond to stable evolution and librating resonant angles. Our computations were focused on the spatial circular restricted three-body model of the Sun-Neptune-TNO system (TNO = trans-Neptunian object). We compare our results with numerical integrations of observed TNOs, which reveal that some of them perform 1:2 resonant, inclined asymmetric librations. For the stable 1:2 TNO librators, we find that their libration seems to be related to the vertically stable planar asymmetric orbits of our model, rather than the three-dimensional ones found in the present study.

Spatial Thinking as the Dimension of Progress in an Astronomy Learning Progression

ERIC Educational Resources Information Center

Plummer, Julia D.

2014-01-01

The big idea of "celestial motion", observational astronomy phenomena explained by the relative position and motion of objects in the solar system and beyond, is central to astronomy in primary and secondary education. In this paper, I argue that students' progress in developing productive, scientific explanations for this class of…

A Native Intelligence Metric for Artificial Systems

DTIC Science & Technology

2002-08-01

an example to help clarify the GCEA. Say we are S and we stumble upon Stonehenge . We don’t wonder whether humans carried the stones (some...stones S encounters that may be exhibiting alignment with celestial bodies at certain seasonal times. S determines that the designer of Stonehenge had...matching of the stones with particular celestial events. The various celestial events and our prehistoric Stonehenge designer’s awareness of these events

Rotational-oscillational motions of the nonrigid Earth about the center of mass

NASA Astrophysics Data System (ADS)

Bondarenko, V. V.; Perepelkin, V. V.

2009-10-01

We use the model of a nearly axisymmetric viscoelastic rigid body to study perturbed rotational-oscillational motions of the Earth's pole. We point out that the Chandler component of oscillations is of celestial-mechanics nature and is caused by the gravitational-tidal actions of the Sun and the Moon. We analyze the pole oscillation excitation mechanism at a frequency close to the Chandler frequency and show that the undamped pole oscillations are caused by the resonance harmonic of the external perturbation at a frequency close to the free nutation frequency. We discuss whether it is possible to solve the problem of constructing a short-term forecast of the pole motion on the basis of a polynomial filter obtained by the least-squares method without taking into account small-scale oscillations caused by wide-band random factors of arbitrary physical nature. In the present paper, we perform numerical simulation of tidal inhomogeneities in the Earth's axial rotation. Attention is mainly paid to the analysis of day length variations on short time intervals with periods less than or equal to one year (interannual oscillations) and to their forecast.

Osculating Keplerian Elements for Highly Non-Keplerian Orbits

DTIC Science & Technology

2017-03-27

1.52133 2 McInnes, C. R., “The Existence and Stability of Families of Displacement Two-Body Orbits”, Celestial Mechanics and Dynamical Astronomy , Vol...j.actaastro.2011.08.012 5 Xu, M. and Xu, S., “Nonlinear dynamical analysis for displaced orbits above a planet”, Celestial Mechanics and Dynamical Astronomy ...Celestial Mechanics and Dynamical Astronomy , Vol. 110, No. 3, 2011, pp. 199-215. doi: 10.1007/s10569-011-9351-5 7 Macdonald, M., McKay, R. J., Vasile, M

On the Astronomical Knowledge and Traditions of Aboriginal Australians

NASA Astrophysics Data System (ADS)

Hamacher, Duane W.

2011-12-01

Historian of science David Pingree defines science in a broad context as the process of systematically explaining perceived or imaginary phenomena. Although Westerners tend to think of science being restricted to Western culture, I argue in this thesis that astronomical scientific knowledge is found in Aboriginal traditions. Although research into the astronomical traditions of Aboriginal Australians stretches back for more than 150 years, it is relatively scant in the literature. We do know that the sun, moon, and night sky have been an important and inseparable component of the landscape to hundreds of Australian Aboriginal groups for thousands (perhaps tens-of-thousands) of years. The literature reveals that astronomical knowledge was used for time keeping, denoting seasonal change and the availability of food sources, navigation, and tidal prediction. It was also important for rituals and ceremonies, birth totems, marriage systems, cultural mnemonics, and folklore. Despite this, the field remains relatively unresearched considering the diversity of Aboriginal cultures and the length of time people have inhabited Australia (well over 40,000 years). Additionally, very little research investigating the nature and role of transient celestial phenomena has been conducted, leaving our understanding of Indigenous astronomical knowledge grossly incomplete. This thesis is an attempt to overcome this deficiency, with a specific focus on transient celestial phenomena. My research, situated in the field of cultural astronomy, draws from the sub-disciplines of archaeoastronomy, ethnoastronomy, historical astronomy, and geomythology. This approach incorporates the methodologies and theories of disciplines in the natural sciences, social sciences, and humanities. This thesis, by publication, makes use of archaeological, ethnographic, and historical records, astronomical software packages, and geographic programs to better understand the ages of astronomical traditions and the role and nature of eclipses, comets, meteors, impact events, and certain variable stars. I also test the hypothesis that certain types of stone arrangements have preferred orientations that probably relate to astronomical phenomena. This research shows that Aboriginal astronomical traditions explain the motions of celestial bodies and the relationship between events in the sky and events on Earth. I explore how Aboriginal people perceived and made use of particular astronomical phenomena, such as meteors and comets, and show that Aboriginal people made careful observations of the motions of celestial bodies. I provide evidence that Aboriginal people noticed the change in brightness of particular stars, described the kinematics of eclipses, explained how lunar phases are related to ocean tides, and acknowledged the relationship between meteors, meteorites, impact events, and impact craters. I then show that linear stone arrangements in New South Wales have a preferred orientation to the cardinal points and explore astronomical reasons for this. In the Appendix, I include biographical details of William Edward Stanbridge, one of the first people to write in depth about Aboriginal astronomical traditions, which were compiled from historic records.

Laplacean Ideology for Preliminary Orbit Determination and Moving Celestial Body Identification in Virtual Epoch

NASA Astrophysics Data System (ADS)

Bykov, O. P.

Any CCD frames with stars or galaxies or clusters and other images must be studied for a searching of moving celestial objects, namely asteroids, comets, artificial Earth satellites inside them. At Pulkovo Astronomical Observatory, new methods and software were elaborated to solve this problem.

Proceedings of the Symposium on Military Space Communications and Operations Held at USAF Academy, Colorado on 2-4 August 1983

DTIC Science & Technology

1983-08-04

IS CURRERTLY OFF; TRANSMITSTHE COM TO TURHE AN N; WAITS FO Procedures are valuable because they provide hCGMDTOTR PROPTION AN POCSSI OELAS...legal and Other Celestial Bodies ,!/ was a regime which has been created by brilliant accomplishment of the world international treaties. These legal...difficulty posed by some controversial provisions in the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies and the

Water in the trail of the Chelyabinsk bolide

NASA Astrophysics Data System (ADS)

Gladysheva, O. G.

2017-09-01

At 03:20 UTC on February 15, 2013 a very bright bolide entered Earth's atmosphere. Fragments of the meteorite fell to the earth's surface. Examination of these fragments revealed that several of them were located directly on the surface of the celestial body [1], while the majority lay at a depth of less than 2.5 m from the surface [2, 3]. The stone meteorite's durability, >15 MPa, corresponded to <1% of the initial mass, while the rest of the object possessed a low durability of 1 MPa [4]. Moreover, Fe3+ hydroxyls were discovered in meteorite samples, the formation of which required water [5]. The glow at the head of the bolide trail, lasting 8 seconds after the flight of the object, and the development of the cloud trail indicate that the celestial body carried water. The Chinese weather satellite Feng-Yun 2D discovered ice debris (water) in the bolide trail [6]. Here, we will demonstrate that the Chelyabinsk chondrite was delivered to the Earth by an ice-bearing celestial body.

Relativistic satellite orbits: central body with higher zonal harmonics

NASA Astrophysics Data System (ADS)

Schanner, Maximilian; Soffel, Michael

2018-06-01

Satellite orbits around a central body with arbitrary zonal harmonics are considered in a relativistic framework. Our starting point is the relativistic Celestial Mechanics based upon the first post-Newtonian approximation to Einstein's theory of gravity as it has been formulated by Damour et al. (Phys Rev D 43:3273-3307, 1991; 45:1017-1044, 1992; 47:3124-3135, 1993; 49:618-635, 1994). Since effects of order (GM/c^2R) × J_k with k ≥ 2 for the Earth are very small (of order 7 × 10^{-10} × J_k) we consider an axially symmetric body with arbitrary zonal harmonics and a static external gravitational field. In such a field the explicit J_k/c^2-terms (direct terms) in the equations of motion for the coordinate acceleration of a satellite are treated first with first-order perturbation theory. The derived perturbation theoretical results of first order have been checked by purely numerical integrations of the equations of motion. Additional terms of the same order result from the interaction of the Newtonian J_k-terms with the post-Newtonian Schwarzschild terms (relativistic terms related to the mass of the central body). These `mixed terms' are treated by means of second-order perturbation theory based on the Lie-series method (Hori-Deprit method). Here we concentrate on the secular drifts of the ascending node <{\\dot{Ω }}> and argument of the pericenter <{\\dot{ω }}>. Finally orders of magnitude are given and discussed.

Reviews: Software.

ERIC Educational Resources Information Center

Mackenzie, Norma N.; And Others

1988-01-01

Reviews four computer software packages including: "The Physical Science Series: Sound" which demonstrates making waves, speed of sound, doppler effect, and human hearing; "Andromeda" depicting celestial motions in any direction; "Biology Quiz: Humans" covering chemistry, cells, viruses, and human biology; and…

The Celestial Bodies in Traditional Armenian Nuptial Songs of Praise

NASA Astrophysics Data System (ADS)

Tigranyan, Marianna

2016-12-01

The universe and its structure have occupied people's minds since the beginning of time. The myths and legends of the ancient cultures are replete with tales about the myriad celestial bodies, planets and stars. Back then, the Ancient Sumerians were phenomenally successful in astronomy; their extensive knowledge is effectively used by astronomers today. The deities were featured as heavenly bodies and were eulogized and revered by the peoples of the Ancient World. At Armenian wedding ceremonies, the groom - traditionally the Crown wearer - was often likened to the Sun, and the bride to the Moon, or sometimes Venus. The newly-married couple was glorified by delightful songs of praise.

Impact of quasar proper motions on the alignment between the International Celestial Reference Frame and the Gaia reference frame

NASA Astrophysics Data System (ADS)

Liu, J.-C.; Malkin, Z.; Zhu, Z.

2018-03-01

The International Celestial Reference Frame (ICRF) is currently realized by the very long baseline interferometry (VLBI) observations of extragalactic sources with the zero proper motion assumption, while Gaia will observe proper motions of these distant and faint objects to an accuracy of tens of microarcseconds per year. This paper investigates the difference between VLBI and Gaia quasar proper motions and it aims to understand the impact of quasar proper motions on the alignment of the ICRF and Gaia reference frame. We use the latest time series data of source coordinates from the International VLBI Service analysis centres operated at Goddard Space Flight Center (GSF2017) and Paris observatory (OPA2017), as well as the Gaia auxiliary quasar solution containing 2191 high-probability optical counterparts of the ICRF2 sources. The linear proper motions in right ascension and declination of VLBI sources are derived by least-squares fits while the proper motions for Gaia sources are simulated taking into account the acceleration of the Solar system barycentre and realistic uncertainties depending on the source brightness. The individual and global features of source proper motions in GSF2017 and OPA2017 VLBI data are found to be inconsistent, which may result from differences in VLBI observations, data reduction and analysis. A comparison of the VLBI and Gaia proper motions shows that the accuracies of the components of rotation and glide between the two systems are 2-4 μas yr- 1 based on about 600 common sources. For the future alignment of the ICRF and Gaia reference frames at different wavelengths, the proper motions of quasars must necessarily be considered.

A Hands-on Exploration of the Retrograde Motion of Mars as Seen from the Earth

ERIC Educational Resources Information Center

Pincelli, M. M.; Otranto, S.

2013-01-01

In this paper, we propose a set of activities based on the use of a celestial simulator to gain insights into the retrograde motion of Mars as seen from the Earth. These activities provide a useful link between the heliocentric concepts taught in schools and those tackled in typical introductory physics courses based on classical mechanics for…

On the asteroid hazard

NASA Astrophysics Data System (ADS)

Eneev, T. M.; Akhmetshin, R. Z.; Efimov, G. B.

2012-04-01

The concept of "space patrol" is considered, aimed at discovering and cataloging the majority of celestial bodies that constitute a menace for the Earth [1, 2]. The scheme of "optical barrier" formed by telescopes of the space patrol is analyzed, requirements to the observation system are formulated, and some schemes of sighting the optical barrier region are suggested (for reliable detection of the celestial bodies approaching the Earth and for determination of their orbits). A comparison is made of capabilities of electro-jet engines and traditional chemical engines for arrangement of patrol spacecraft constellation in the Earth's orbit.

General Methodology for Designing Spacecraft Trajectories

NASA Technical Reports Server (NTRS)

Condon, Gerald; Ocampo, Cesar; Mathur, Ravishankar; Morcos, Fady; Senent, Juan; Williams, Jacob; Davis, Elizabeth C.

2012-01-01

A methodology for designing spacecraft trajectories in any gravitational environment within the solar system has been developed. The methodology facilitates modeling and optimization for problems ranging from that of a single spacecraft orbiting a single celestial body to that of a mission involving multiple spacecraft and multiple propulsion systems operating in gravitational fields of multiple celestial bodies. The methodology consolidates almost all spacecraft trajectory design and optimization problems into a single conceptual framework requiring solution of either a system of nonlinear equations or a parameter-optimization problem with equality and/or inequality constraints.

The consistency of the current conventional celestial and terrestrial reference frames and the conventional EOP series

NASA Astrophysics Data System (ADS)

Heinkelmann, R.; Belda-Palazon, S.; Ferrándiz, J.; Schuh, H.

2015-08-01

For applications in Earth sciences, navigation, and astronomy the celestial (ICRF) and terrestrial (ITRF) reference frames as well as the orientation among them, the Earth orientation parameters (EOP), have to be consistent at the level of 1 mm and 0.1 mm/yr (GGOS recommendations). We assess the effect of unmodelled geophysical signals in the regularized coordinates and the sensitivity with respect to different a priori EOP and celestial reference frames. The EOP are determined using the same VLBI data but with station coordinates fixed on different TRFs. The conclusion is that within the time span of data incorporated into ITRF2008 (Altamimi, et al., 2011) the ITRF2008 and the IERS 08 C04 are consistent. This consistency involves that non-linear station motion such as unmodelled geophysical signals partly affect the IERS 08 C04 EOP. There are small but not negligible inconsistencies between the conventional celestial reference frame, ICRF2 (Fey, et al., 2009), the ITRF2008 and the conventional EOP that are quantified by comparing VTRF2008 (Böckmann, et al., 2010) and ITRF2008.

Thai student existing understanding about the solar system model and the motion of the stars

NASA Astrophysics Data System (ADS)

Anantasook, Sakanan; Yuenyong, Chokchai

2018-01-01

The paper examined Thai student existing understanding about the solar system model and the motion of the stars. The participants included 141 Grade 9 students in four different schools of the Surin province, Thailand. Methodology regarded interpretive paradigm. The tool of interpretation included the Student Celestial Motion Conception Questionnaire (SCMCQ) and informal interview. Given understandings in the SCMCQ were read through and categorized according to students' understandings. Then, students were further probed as informal interview. Students' understandings in each category were counted and percentages computed. Finally, students' understandings across four different schools were compared and contrasted using the percentage of student responses in each category. The findings revealed that most students understand about Sun-Moon-Earth (SME) system and solar system model as well, they can use scientific explanations to explain the celestial objects in solar system and how they orbiting. Unfortunately, most of students (more than 70%) never know about the Polaris, the North Star, and 90.1% of them never know about the ecliptic, and probably also the 12 zodiac constellations. These existing understanding suggested some ideas of teaching and learning about solar system model and the motion of the stars. The paper, then, discussed some learning activities to enhance students to further construct meaning about solar system model and the motion of the stars.

Upgrading Our EPO Through Focused Astronomy Education Research

NASA Astrophysics Data System (ADS)

Slater, Stephanie J.; Dye, A.

2012-01-01

Not so long ago, astronomers visiting schools in Hawaii tried to build awareness among school children and teachers about how stars move across the sky, the nature of planets orbiting our sun, and the physical processes governing stars and galaxies. While these efforts were undertaken with all good intentions, they were often based on our collective understanding of how Mainland children come to know astronomy topics, and with a Western worldview. Research observations of Hawaiian elementary school children indicate that Hawaiian children understand far more about the skies than could have been predicted from the behavior of Mainland children, or from the body of literature on children's understanding of astronomy. Analysis of elementary students’ responses to a kumu's, or teacher's questions relating to the celestial sphere indicate that these students posses a deep knowledge of the night sky and celestial motions. This knowledge base is fluent across two cultural systems of constellations, and is predictive. In an era of curriculum development based upon learning progressions, it appears that Native Hawaiian students possess unexpected knowledge that is well poised to interfere with conventional educational and public outreach approaches if not taken into account. Further, these findings suggest that further inquiry must be made into the astronomical thinking of minority populations prior to the unilateral implementation of national science education standards.

Chaos in navigation satellite orbits caused by the perturbed motion of the Moon

NASA Astrophysics Data System (ADS)

Rosengren, Aaron J.; Alessi, Elisa Maria; Rossi, Alessandro; Valsecchi, Giovanni B.

2015-06-01

Numerical simulations carried out over the past decade suggest that the orbits of the Global Navigation Satellite Systems are unstable, resulting in an apparent chaotic growth of the eccentricity. Here, we show that the irregular and haphazard character of these orbits reflects a similar irregularity in the orbits of many celestial bodies in our Solar system. We find that secular resonances, involving linear combinations of the frequencies of nodal and apsidal precession and the rate of regression of lunar nodes, occur in profusion so that the phase space is threaded by a devious stochastic web. As in all cases in the Solar system, chaos ensues where resonances overlap. These results may be significant for the analysis of disposal strategies for the four constellations in this precarious region of space.

Chaotic dynamics in the physical sciences (Lewis Fry Richardson Medal Lecture)

NASA Astrophysics Data System (ADS)

Ott, Edward

2017-04-01

Chaos was discovered at the end of the 19th century by Poincare in his famous work on the motion of N>2 celestial bodies interacting through gravitational attraction. Although steady progress was made by mathematicians following Poincare's work, the widespread impact and development of chaos in the physical sciences is comparatively recent, i.e., approximately starting in the 1970's. This talk will review and comment on this history and will give some examples illustrating the types of questions, problems and results arising from perspectives resulting from the widespread participation of physical scientists in chaos research. One of these examples will be from our work on data assimilation for weather prediction [ Ott et al., Tellus A vol.56, 415 (2004); Patil, Phys. Rev. Lett. vol.86, 5878 (2001)].

General-relativistic celestial mechanics. 4: Theory of satellite motion

NASA Astrophysics Data System (ADS)

Damour, T.; Soffel, M.; Xu, C.

1993-09-01

The basic equations needed for developing a complete relativistic theory of artificial Earth satellites are explicitly written down. These equations are given both in a local, geocentric frame and in the global, barycentric one. They are derived within our recently introduced general-relativistic celestial mechanics framework. Our approach is more satisfactory than previous ones, especially with regard to its consistency, completeness, and flexibility. In particular, the problem of representing the relativistic gravitational effects associated with the quadrupole and higher multipole moments of the moving Earth, which caused difficulties in several other approaches, is easily dealth with in our approach, thanks to the use of previously developed tools: definition of relativistic multipole moments and transformation theory between reference frames. With this last paper in a series, we hope to indicate the way of using our formalism in specific problems in applied celestial mechanics and astrometry.

The Størmer problem for an aligned rotator

NASA Astrophysics Data System (ADS)

Epp, V.; Pervukhina, O. N.

2018-03-01

The effective potential energy of the particles in the field of rotating uniformly magnetized celestial body is investigated. The axis of rotation coincides with the axis of the magnetic field. Electromagnetic field of the body is composed of a dipole magnetic and quadrupole electric fields. The geometry of the trapping regions is studied as a function of the magnetic field magnitude and the rotation speed of the body. Examples of the potential energy topology for different values of these parameters are given. The main difference from the classical Størmer problem is that the single toroidal trapping region predicted by Størmer is divided into equatorial and off-equatorial trapping regions. Applicability of the idealized model of a rotating uniformly magnetized sphere with a vacuum magnetosphere to real celestial bodies is discussed.

Nonuniformity of the Earth's rotation and the motion of the poles

NASA Technical Reports Server (NTRS)

Sidorenkov, N. S.

1983-01-01

The study of the nonuniformity of the Earth's rotation and the motion of the poles has great practical and theoretical significance. This study makes it possible to determine the coordinates of celestial and terrestrial objects, and to gain information in many domains of earth science. This paper reviews studies of rotation nonuniformity and polar motion, giving attention to astronomical data; the nature of periodic oscillations of the Earth's rotation; the nature of long-period variations of the Earth's rotation rate; and the use of Earth-rotation data in hydrometeorology.

Gaia, Helios, Selene and Ouranos: the three principal celestial bodies and the sky in the ancient Greek cosmogony

NASA Astrophysics Data System (ADS)

Theodossiou, Efstratios; Manimanis, Vassilios N.; Dimitrijević, Milan S.; Mantarakis, Petros

In this article we consider the role of the three principal celestial bodies, the Earth (Gaia), the Sun (Helios) and the Moon (Selene), as well as the Sky (Ouranos) in the ancient Greek cosmogony. This is done by the analysis of antique Greek texts like Orphic Hymns and the literary remains of the writers and philosophers like Aeschylus, (Pseudo) Apollodorus, Apollonius Rhodius, Aristotle, Euripides, Hesiod, Homer, Hyginus, Nonnus, Pausanias, Pindar and Sophocles, as well as by the analysis of texts of Roman writers like Cicero, Ovid and Pliny.

The IAA Cosmic Study 'Protecting the Environment of Celestial Bodies'

NASA Astrophysics Data System (ADS)

Rettberg, Petra; Hofmann, Mahulena; Williamson, Mark

The study group tasked with producing this International Academy of Astronautics (IAA) `Cosmic Study' on Protecting the Environment of Celestial Bodies was formed under the aus-pices of IAA Commission V (Space Policy, Law Economy). The members of the international, multidisciplinary team assembled to undertake the Study accept, as a premise, the Planetary Protection Policy guidelines developed by COSPAR, which differentiate the degree of protec-tion according to the type of space activity and the celestial body under investigation (such that fly-by missions have less stringent requirements than lander missions, while Mars is `better protected' than the Moon). However, this Study goes deliberately beyond the interpretation of `Planetary Protection' as a set of methods for protecting the planets from biological con-tamination and extends consideration to the geophysical, industrial and cultural realms. The Study concludes that, from the perspective of current and future activities in outer space, present measures aimed at protecting the space environment are insufficient. Deficiencies in-clude a lack of suitable in-situ methods of chemical and biological detection and the absence of a systematic record of radioactive contaminants. Other issues identified by the Study include an insufficient legal framework, a shortage of effective economic tools and a lack of political will to address these concerns. It is expected that new detection methods under development, and the resultant increase in microbiological knowledge of the planetary surfaces, will lead to changes in the COSPAR planetary protection guidelines and bioburden limits. It is important, however, that any new approaches should not hamper future exploration and exploitation of celestial bodies more than absolutely necessary. The Study addresses the need to find a balance between protection and freedom of action. From a legal perspective, the Study concludes that a general consensus on protection of the environment of the Moon and other celestial bodies should be sought among spacefaring states, while the question of new laws and regulations should be deliberated in the UN and scientific organisations. In doing so, it is recommended that experience in formulating the Antarctic Treaty System and other terrestrial environmen-tal accords should be taken into account. In general terms, it is expected that the majority of space activities would remain untouched by any future policies and regulations, to ensure that space exploration and exploitation remains open to future generations. But this philosophy brings with it a responsibility to protect the freedoms of those future generations from the ill-conceived practices of the present. As a result, activities that threaten the environments of celestial bodies, and our cultural heritage, should be identified, mitigated and discouraged (either by policy or by law).

Celestial reference frames and the gauge freedom in the post-Newtonian mechanics of the Earth-Moon system

NASA Astrophysics Data System (ADS)

Kopeikin, Sergei; Xie, Yi

2010-11-01

We introduce the Jacobi coordinates adopted to the advanced theoretical analysis of the relativistic Celestial Mechanics of the Earth-Moon system. Theoretical derivation utilizes the relativistic resolutions on reference frames adopted by the International Astronomical Union (IAU) in 2000. The resolutions assume that the Solar System is isolated and space-time is asymptotically flat at infinity and the primary reference frame covers the entire space-time, has its origin at the Solar System barycenter (SSB) with spatial axes stretching up to infinity. The SSB frame is not rotating with respect to a set of distant quasars that are assumed to be at rest on the sky forming the International Celestial Reference Frame (ICRF). The second reference frame has its origin at the Earth-Moon barycenter (EMB). The EMB frame is locally inertial and is not rotating dynamically in the sense that equation of motion of a test particle moving with respect to the EMB frame, does not contain the Coriolis and centripetal forces. Two other local frames—geocentric and selenocentric—have their origins at the center of mass of Earth and Moon respectively and do not rotate dynamically. Each local frame is subject to the geodetic precession both with respect to other local frames and with respect to the ICRF because of their relative motion with respect to each other. Theoretical advantage of the dynamically non-rotating local frames is in a more simple mathematical description of the metric tensor and relative equations of motion of the Moon with respect to Earth. Each local frame can be converted to kinematically non-rotating one after alignment with the axes of ICRF by applying the matrix of the relativistic precession as recommended by the IAU resolutions. The set of one global and three local frames is introduced in order to decouple physical effects of gravity from the gauge-dependent effects in the equations of relative motion of the Moon with respect to Earth.

Enceladus: a vanishing satellite

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic activity is observed. Every second, the mass of 200 kg is ejecting into space. The size of the satellite directly after accretion (this body is referred here as proto-Enceladus) is unknown. It can be estimated in two ways. First, if the average mass outflow is equal to the present rate then the satellite’s original mass was 30% bigger than today. Second, we assume here that density of proto-Enceladus was equal to the present density of Mimas because they were formed in the same part of the nebula. Mimas is dead, so it preserves original composition. Both approaches give similar initial Enceladus’ radius ( 296 km) and its surface area ( 1.1×106 km2). The present values are: 252 km and 7.99×105 km2. The loss of matter should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding, and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic model that could explain this paradox. The volatiles escape from the hot region through the fractures forming plumes in the space. The loss of the volatiles results in a void, an instability, and motion of solid matter into hot region to fill the void in statu nascendi. The motion includes: (i) Subsidence of the lithosphere of SPT. (ii) Flow of matter in the mantle. (iii) Motion of lithospheric plates adjacent to SPT towards the active region. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is 0.05 mm·yr-1. However, all three types of motion are probably important, so the subsidence is slower but mantle flow and plates’ motion also play a role in filling the void. Note that in our model reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. Note also that we do not know the present age of the satellite surface. Age assessment depends on the assumed model of the flux of meteorites. For the lunar-like flux, cratered plains of Enceladus are 4.2 Gyr old, and only 1.7 Gyr old, if cometary impact rates are used (1, 2). If ‘cometary’ chronology is correct then we have no data concerning 2/3 of Enceladus history. During that time there could be a number of activity cycles, and the total decrease of the surface area could be 300,000 km2. If our hypothesis is confirmed, then Enceladus will be an exceptional body, possibly representing a new class of celestial bodies: bodies decreasing as a result of endogenic activity. Are other bodies similar to Enceladus? Dione seems be a good candidate. Its activity is predicted and observed (3, 4). Its gravity is too low to retain gases. Its present high density could be a result of partial loss of volatiles in the past. Moreover, it is in orbit-orbit resonance, so substantial tidal heating is possible. Acknowledgments This work was partially supported by the National Science Centre (grant 2011/01/B/ST10/06653). References and Notes: 1. J.R., Spencer, et al. Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer Science, (2009), p. 683. 2. K. Zahnle et al., Cratering rates in the outer Solar System. Icarus 163, 263 (2003). 3. JPL press release. Cassini finds hints of activity at Saturn moon Dione, http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130529/ May, 29 (2013) 4. L. Czechowski, Parameterized model of convection driven by tidal and radiogenic heating. Adv. Space Res. 38, 788 (2006).

Enceladus: a vanishing satellite

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2014-05-01

Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic activity is observed. Every second, the mass of ~200 kg is ejecting into space. The size of the satellite directly after accretion (this body is referred here as proto-Enceladus) is unknown. It can be estimated in two ways. First, if the average mass outflow is equal to the present rate then the satellite's original mass was ~30% bigger than today. Second, we assume here that density of proto-Enceladus was equal to the present density of Mimas because they were formed in the same part of the nebula. Mimas is dead, so it preserves original composition. Both approaches give similar initial Enceladus' radius (~296 km) and its surface area (~1.1×106 km2). The present values are: 252 km and 7.99×105 km2. The loss of matter should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding, and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic model that could explain this paradox. The volatiles escape from the hot region through the fractures forming plumes in the space. The loss of the volatiles results in a void, an instability, and motion of solid matter into hot region to fill the void in statu nascendi. The motion includes: Subsidence of the lithosphere of SPT. Flow of matter in the mantle. Motion of lithospheric plates adjacent to SPT towards the active region. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is ~0.05 mm·yr-1. However, all three types of motion are probably important, so the subsidence is slower but mantle flow and plates' motion also play a role in filling the void. Note that in our model reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. Note also that we do not know the present age of the satellite surface. Age assessment depends on the assumed model of the flux of meteorites. For the lunar-like flux, cratered plains of Enceladus are 4.2 Gyr old, and only 1.7 Gyr old, if cometary impact rates are used (1,2). If 'cometary' chronology is correct then we have no data concerning 2/3 of Enceladus history. During that time there could be a number of activity cycles, and the total decrease of the surface area could be 300,000 km2. If our hypothesis is confirmed, then Enceladus will be an exceptional body, possibly representing a new class of celestial bodies: bodies decreasing as a result of endogenic activity. Are other bodies similar to Enceladus? Dione seems be a good candidate. Its activity is predicted and observed(3,4). Its gravity is too low to retain gases. Its present high density could be a result of partial loss of volatiles in the past. Moreover, it is in orbit-orbit resonance, so substantial tidal heating is possible. Acknowledgments This work was partially supported by the National Science Centre (grant 2011/01/B/ST10/06653). References and Notes: 1. J.R., Spencer, et al. Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer Science, (2009), p. 683. 2. K. Zahnle et al., Cratering rates in the outer Solar System. Icarus 163, 263 (2003). 3. JPL press release. Cassini finds hints of activity at Saturn moon Dione, http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130529/ May, 29 (2013) 4. L. Czechowski, Parameterized model of convection driven by tidal and radiogenic heating. Adv. Space Res. 38, 788 (2006).

Dynamics of Natural and Artificial Celestial Bodies

NASA Astrophysics Data System (ADS)

Pretka-Ziomek, Halina; Wnuk, Edwin; Seidelmann, P. Kenneth; Richardson, David.

2002-01-01

This volume contains papers presented at the US/European Celestial Mechanics Workshop organized by the Astronomical Observatory of Adam Mickiewicz University in Poznan, Poland and held in Poznan, from 3 to 7 July 2000. The purpose of the workshop was to identify future research in celestial mechanics and astrometry and encourage collaboration among scientists from eastern and western countries. Also an emphasis was placed on attracting young members of the fields from around the world and encouraging them to undertake new research efforts needed for advancements in those fields. There was a full program of invited and contributed presentations on selected subjects and each day ended with a discussion period on a general subject in celestial mechanics. The discussion topics and the leaders were: Resonances and Chaos -- A. Morbidelli; Artificial Satellite Orbits -- K.T. Alfriend; Near Earth Objects -- K. Muinonen; Small Solar System Bodies -- I. Williams; and Summary -- P.K. Seidelmann. The goal of the discussions was to identify what we did not know and how we might further our knowledge. It was felt, in addition, that Poznan, Poland, with a core of scientists covering a range of ages, would provide an example of how a research and educational group could be developed elsewhere. Also, Poznan is a central location convenient to eastern and western countries. Thus, the gathering of people and the papers presented are to be the bases for building the future of astrometry and celestial mechanics. Link: http://www.wkap.nl/prod/b/1-4020-0115-0

Relation Between the Celestial Reference System and the Terrestrial Reference System of a Rigid Earth

NASA Astrophysics Data System (ADS)

Aoki, Shinko

1987-03-01

A relation between the Celestial Reference System (CRS) and the Terrestrial Reference System is established theoretically by solving the equations of motion of a rigid Earth under the influence of the Sun and the Moon up to the second order perturbation. The solutions include not only nutation including Oppolzer terms but also the right ascension of the dynamical departure point (DP), as well as the wobble matrix. We have found that the kinematical definition of the Non-Rotating Origin NRO (for which our term is DP) given by Capitaine, Guinot and Souchay (1987) is not entirely equivalent to that included in the solutions of the equations of motion but shows perturbation, in particular when this is taken on the instantaneous equator. Besides this serious fault, we feel little merit in taking the DP as reference: (1) Unnecessary spurious mixed secular terms appear which come from the geometrical configuration that the DP leaves far and far from the ecliptic. (2) the DP moves secularly as well as oscillating with respect to space; this literally contradicts the term ‘NRO’, or is at least misleading. (3) It does not free us from the precession uncertainty to adopt DP as reference, since we cannot avoid virtual proper motions in terms of the current CRS. (4) No terms ignored hitherto are introduced, even if we take the DP properly chosen, i.e., on the equator of the celestial ephemeris pole. The transformation is only mathematical. There is no sufficient reason to take it instead of the equinox, which is observable in principle, as reference at the cost of the labor of changing all the textbooks, ephemerides, data and computer software now existing.

Semi-analytical integration of the Earth's precession-nutation based on the GCRS coordinates of the CIP unit vector

NASA Astrophysics Data System (ADS)

Capitaine, N.; Folgueira, M.

2012-12-01

In a previous paper (Capitaine et al. 2006), referred here as Paper I, we demonstrated the possibility of integrating the Earth's rotational motion in terms of the coordinates (X, Y ) of the celestial intermediate pole (CIP) unit vector in the Geocentric celestial reference system (GCRS). Here, we report on the approach that has been followed for solving the equations in the case of an axially symmetric rigid Earth and the semi-analytical (X, Y ) solution obtained from the expression of the external torque acting on the Earth derived from the most complete semi-analytical solutions for the Earth, Moon and planets.

Anania Shirakatsi's Cosmographical and Natural Philosophical Views

NASA Astrophysics Data System (ADS)

Danielyan, Eduard

2014-10-01

The observation of the heaven and celestial bodies has taken place since ancient times in the Armenian Highland. The notions of the sphericity of the Earth and celestial bodies, and other theses (about elements, comparative sizes of celestial bodies, antipodes, earthquakes, criticism of astrology, etc.) were reflected and elaborated in "Cosmography" of Anania Shirakatsi (VII century AD), as well as "Ashkharhatsoyts" ("Geography") of Movses Khorenatsi (V century AD) and his continuer Anania Shirakatsi. The road of observation and study of the Milky Way - the fundamental kernel of the development of astronomy - has led the human mind to galaxies, the cognition of the infinite capabilities of the development of matter, that is to say, from the studies of the elements constituting the Earth and other spherical bodies in the Universe (studied by Aristotle) to the Heliocentric system by Copernicus (1473-1543), from the cosmogonic ideas of Democritus (460-370 BC) about the multitude of worlds and the character of the Milky Way and their reflection in natural philosophic views of Anania Shirakatsi to the discovery of non-stationary objects and processes in the Universe owing to the activity of the nuclei of galaxies, according to the cosmogonic conception of academician Victor Ambartsumyan. Anania Shirakatsi's scientific heritage greatly contributed to the development of Armenian and world natural scientific thought.

Baillaud, Édouard Benjamin (1848-1934)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

French astronomer, became director of Toulouse Observatory and Paris Observatory. He worked in celestial mechanics, especially on the motions of the satellites of Saturn, and inaugurated the telegraphy of time signals from the Paris Observatory via the Eiffel Tower. First president of the International Astronomical Union....

Constructing a celestial calendar wheel

NASA Astrophysics Data System (ADS)

Cousineau, Sarah M.

1999-11-01

When we are asked to consider astronomical monuments of historical significance, we often think of Stonehenge, Mayan cities, or Aztec calendars. Few of us in the United States are prompted to look in our own backyard, where Native Americans spent centuries monitoring the rhythmic motions of the skies.

Determination of Galactic Aberration from VLBI Measurements and Its Effect on VLBI Reference Frames and Earth Orientation Parameters.

NASA Astrophysics Data System (ADS)

MacMillan, D. S.

2014-12-01

Galactic aberration is due to the motion of the solar system barycenter around the galactic center. It results in a systematic pattern of apparent proper motion of radio sources observed by VLBI. This effect is not currently included in VLBI analysis. Estimates of the size of this effect indicate that it is important that this secular aberration drift be accounted for in order to maintain an accurate celestial reference frame and allow astrometry at the several microarcsecond level. Future geodetic observing systems are being designed to be capable of producing a future terrestrial reference frame with an accuracy of 1 mm and stability of 0.1 mm/year. We evaluate the effect galactic aberration on attaining these reference frame goals. This presentation will discuss 1) the estimation of galactic aberration from VLBI data and 2) the effect of aberration on the Terrestrial and Celestial Reference Frames and the Earth Orientation Parameters that connect these frames.

A long time span relativistic precession model of the Earth

NASA Astrophysics Data System (ADS)

Tang, Kai; Soffel, Michael H.; Tao, Jin-He; Han, Wen-Biao; Tang, Zheng-Hong

2015-04-01

A numerical solution to the Earth's precession in a relativistic framework for a long time span is presented here. We obtain the motion of the solar system in the Barycentric Celestial Reference System by numerical integration with a symplectic integrator. Special Newtonian corrections accounting for tidal dissipation are included in the force model. The part representing Earth's rotation is calculated in the Geocentric Celestial Reference System by integrating the post-Newtonian equations of motion published by Klioner et al. All the main relativistic effects are included following Klioner et al. In particular, we consider several relativistic reference systems with corresponding time scales, scaled constants and parameters. Approximate expressions for Earth's precession in the interval ±1 Myr around J2000.0 are provided. In the interval ±2000 years around J2000.0, the difference compared to the P03 precession theory is only several arcseconds and the results are consistent with other long-term precession theories. Supported by the National Natural Science Foundation of China.

The Origin Billions Star Survey: Galactic Explorer

DTIC Science & Technology

2006-10-18

Using OBSS, it will be possible to measure proper motions of galaxies (the motion in the plane of the sky) out to the distance of the Virgo Cluster ...within the Milky Way, as well as the local group toward the Virgo Cluster , will also be discerned at the microarcsecond level. All of this will be...supercluster of galaxies, dark matter, star for- mation, open clusters , the solar system, and the celestial ref- erence frame. This research was supported by

Refraction effects of atmosphere on geodetic measurements to celestial bodies

NASA Technical Reports Server (NTRS)

Joshi, C. S.

1973-01-01

The problem is considered of obtaining accurate values of refraction corrections for geodetic measurements of celestial bodies. The basic principles of optics governing the phenomenon of refraction are defined, and differential equations are derived for the refraction corrections. The corrections fall into two main categories: (1) refraction effects due to change in the direction of propagation, and (2) refraction effects mainly due to change in the velocity of propagation. The various assumptions made by earlier investigators are reviewed along with the basic principles of improved models designed by investigators of the twentieth century. The accuracy problem for various quantities is discussed, and the conclusions and recommendations are summarized.

Exogeoconservation: Protecting geological heritage on celestial bodies

NASA Astrophysics Data System (ADS)

Matthews, Jack J.; McMahon, Sean

2018-08-01

Geoconservation is an increasingly widely adopted theoretical, practical and administrative approach to the protection of geological and geomorphological features of special scientific, functional, historic, cultural, aesthetic, or ecological value. Protected sites on Earth include natural rocky outcrops, shorelines, river banks, and landscapes, as well as human-made structures such as road cuts and quarries exposing geological phenomena. However, geoconservation has rarely been discussed in the context of other rocky and icy planets, rings, moons, dwarf planets, asteroids, or comets, which present extraordinarily diverse, beautiful, and culturally, historically and scientifically important geological phenomena. Here we propose to adapt geoconservation strategies for protecting the geological heritage of these celestial bodies, and introduce the term 'exogeoconservation' and other associated terms for this purpose. We argue that exogeoconservation is acutely necessary for the scientific exploration and responsible stewardship of celestial bodies, and suggest how this might be achieved and managed by means of international protocols. We stress that such protocols must be sensitive to the needs of scientific, industrial, and other human activities, and not unduly prohibitive. However, with space exploration and exploitation likely to accelerate in coming decades, it is increasingly important that an internationally agreed, holistic framework be developed for the protection of our common 'exogeoheritage'.

Comments on 'The origin of the earth-moon system'

NASA Astrophysics Data System (ADS)

Savic, P.; Teleki, G.

1986-10-01

A new hypothesis for the origin of the earth-moon system is developed on the basis of Savic's (1961) theory of the origin of rotation of celestial bodies. According to the theory, the cooling off and contraction due to gravitational attraction on vast particle systems, with the pushing out of electrons from atom shells, results in the continually increasing density of a planet; the expulsion of electrons causes formation of a magnetic field by which a rotational motion is brought about. It is argued that these conditions are consistent with the formation of the earth and the moon from a unique protoplanet which, in course of the rotation, has taken shape of a large Jacobi ellipsoid. New condensation forming along the edge of the ellipsoid led to the creation of the dual earth-moon system.

REVIEWS OF TOPICAL PROBLEMS: The hydromagnetic dynamo as the source of planetary, solar, and galactic magnetism

NASA Astrophysics Data System (ADS)

Zeldovich, Ya B.; Ruzmaĭkin, A. A.

1987-06-01

The magnetism of most celestial bodies, i.e., planets, stars, and galaxies, is of hydromagnetic origin. The turbulent hydromagnetic dynamo is the principal mechanism whereby the magnetic field is amplified and maintained, and the theory of this phenomenon has advanced significantly in recent years. This review discusses applications of the theory of the turbulent dynamo to real objects, taking the Sun, the Earth, and the Galaxy as examples. Most of the discussion is concentrated on the large-scale magnetic field averaged over turbulent fluctuations. The average field is amplified and maintained by the average helicity of turbulent motion and large-scale shear flows such as differential rotation. The dynamo theory explains striking phenomena such as geomagnetic field reversal, the solar cycle, and the ring and bisymmetric structure of spiral galaxies.

Periodic Orbit Families in the Gravitational Field of Irregular-shaped Bodies

NASA Astrophysics Data System (ADS)

Jiang, Yu; Baoyin, Hexi

2016-11-01

The discovery of binary and triple asteroids in addition to the execution of space missions to minor celestial bodies in the past several years have focused increasing attention on periodic orbits around irregular-shaped celestial bodies. In the present work, we adopt a polyhedron shape model for providing an accurate representation of irregular-shaped bodies and employ the model to calculate their corresponding gravitational and effective potentials. We also investigate the characteristics of periodic orbit families and the continuation of periodic orbits. We prove a fact, which provides a conserved quantity that permits restricting the number of periodic orbits in a fixed energy curved surface about an irregular-shaped body. The collisions of Floquet multipliers are maintained during the continuation of periodic orbits around the comet 1P/Halley. Multiple bifurcations in the periodic orbit families about irregular-shaped bodies are also discussed. Three bifurcations in the periodic orbit family have been found around the asteroid 216 Kleopatra, which include two real saddle bifurcations and one period-doubling bifurcation.

Post-Newtonian celestial dynamics in cosmology: Field equations

NASA Astrophysics Data System (ADS)

Kopeikin, Sergei M.; Petrov, Alexander N.

2013-02-01

Post-Newtonian celestial dynamics is a relativistic theory of motion of massive bodies and test particles under the influence of relatively weak gravitational forces. The standard approach for development of this theory relies upon the key concept of the isolated astronomical system supplemented by the assumption that the background spacetime is flat. The standard post-Newtonian theory of motion was instrumental in the explanation of the existing experimental data on binary pulsars, satellite, and lunar laser ranging, and in building precise ephemerides of planets in the Solar System. Recent studies of the formation of large-scale structures in our Universe indicate that the standard post-Newtonian mechanics fails to describe more subtle dynamical effects in motion of the bodies comprising the astronomical systems of larger size—galaxies and clusters of galaxies—where the Riemann curvature of the expanding Friedmann-Lemaître-Robertson-Walker universe interacts with the local gravitational field of the astronomical system and, as such, cannot be ignored. The present paper outlines theoretical principles of the post-Newtonian mechanics in the expanding Universe. It is based upon the gauge-invariant theory of the Lagrangian perturbations of cosmological manifold caused by an isolated astronomical N-body system (the Solar System, a binary star, a galaxy, and a cluster of galaxies). We postulate that the geometric properties of the background manifold are described by a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker metric governed by two primary components—the dark matter and the dark energy. The dark matter is treated as an ideal fluid with the Lagrangian taken in the form of pressure along with the scalar Clebsch potential as a dynamic variable. The dark energy is associated with a single scalar field with a potential which is hold unspecified as long as the theory permits. Both the Lagrangians of the dark matter and the scalar field are formulated in terms of the field variables which play a role of generalized coordinates in the Lagrangian formalism. It allows us to implement the powerful methods of variational calculus to derive the gauge-invariant field equations of the post-Newtonian celestial mechanics of an isolated astronomical system in an expanding universe. These equations generalize the field equations of the post-Newtonian theory in asymptotically flat spacetime by taking into account the cosmological effects explicitly and in a self-consistent manner without assuming the principle of liner superposition of the fields or a vacuole model of the isolated system, etc. The field equations for matter dynamic variables and gravitational field perturbations are coupled in the most general case of an arbitrary equation of state of matter of the background universe. We introduce a new cosmological gauge which generalizes the de Donder (harmonic) gauge of the post-Newtonian theory in asymptotically flat spacetime. This gauge significantly simplifies the gravitational field equations and allows one to find out the approximations where the field equations can be fully decoupled and solved analytically. The residual gauge freedom is explored and the residual gauge transformations are formulated in the form of the wave equations for the gauge functions. We demonstrate how the cosmological effects interfere with the local system and affect the local distribution of matter of the isolated system and its orbital dynamics. Finally, we worked out the precise mathematical definition of the Newtonian limit for an isolated system residing on the cosmological manifold. The results of the present paper can be useful in the Solar System for calculating more precise ephemerides of the Solar System bodies on extremely long time intervals, in galactic astronomy to study the dynamics of clusters of galaxies, and in gravitational wave astronomy for discussing the impact of cosmology on generation and propagation of gravitational waves emitted by coalescing binaries and/or merging galactic nuclei.

Global Tectonics of Enceladus: Numerical Model

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2016-10-01

Introduction: Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of 200 kg is ejected into space from the South Polar Terrain (SPT) - [1]. The loss of matter from the body's interior should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic process that could explain this paradox. Our hypotheses states that the mass loss from SPT is the main driving mechanism of the following tectonic processes: subsidence of SPT, flow in the mantle and motion of adjacent tectonic plates. The hypotheses is presented in [2], [3] and[4].We suggest that the loss of the volatiles results in a void, an instability, and motion of solid matter to fill the void. The motion is presented at the Fig.1 and includes:Subsidence of the 'lithosphere' of SPT.Flow of the matter in the mantle.Motion of plates adjacent to SPT towards the active regionMethods and results: The numerical model of processes presented is developed. It is based on the equations of continuous media..If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is 0.05 mmyr-1. However, numerical calculations indicate that all three types of motion are usually important. The role of a given motion depends on the viscosity distribution. Generally, for most of the models the subsidence is 0.02 mmyr-1, but mantle flow and plates' motion also play a role in filling the void. The preliminary results of the numerical model indicate also that the velocity of adjacent plates could be 0.02 mmyr-1 for the Newtonian rheology.Note that in our model the reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. The SPT does not have to be compressed, so the open "tiger stripes" could exist for long time. e suppose that it means the end of activity in the given region.

The effect of the Earth's oblateness on the Moon's physical libration in latitude

NASA Astrophysics Data System (ADS)

Kondratyev, B. P.

2013-05-01

The Moon's physical libration in latitude generated by gravitational forces caused by the Earth's oblateness has been examined by a vector analytical method. Libration oscillations are described by a close set of five linear inhomogeneous differential equations, the dispersion equation has five roots, one of which is zero. A complete solution is obtained. It is revealed that the Earth's oblateness: a) has little effect on the instantaneous axis of Moon's rotation, but causes an oscillatory rotation of the body of the Moon with an amplitude of 0.072″ and pulsation period of 16.88 Julian years; b) causes small nutations of poles of the orbit and of the ecliptic along tight spirals, which occupy a disk with a cut in a center and with radius of 0.072″. Perturbations caused by the spherical Earth generate: a) physical librations in latitude with an amplitude of 34.275″; b) nutational motion for centers of small spiral nutations of orbit (ecliptic) pole over ellipses with semi-major axes of 113.850″ (85.158″) and the first pole rotates round the second one along a circle with radius of 28.691″; c) nutation of the Moon's celestial pole over an ellipse with a semi-major axis of 45.04″ and with an axes ratio of about 0.004 with a period of T = 27.212 days. The principal ellipse's axis is directed tangentially with respect to the precession circumference, along which the celestial pole moves nonuniformly nearly in one dimension. In contrast to the accepted concept, the latitude does not change while the Moon's poles of rotation move. The dynamical reason for the inclination of the Moon's mean equator with respect to the ecliptic is oblateness of the body of the Moon.

Observations of an indigenous Hawaiian planetarium operator: Astronomy content knowledge of Hawaiian school children

NASA Astrophysics Data System (ADS)

Dye, Ahia G.; Ha`o, Celeste; Slater, Timothy F.; Slater, Stephanie J.

2015-08-01

Not so long ago, astronomers visiting schools in Hawaii tried to build awareness among school children and teachers about how stars move across the sky, the nature of planets orbiting our sun, and the physical processes governing stars and galaxies. While these efforts were undertaken with all good intentions, they were often based on our collective understanding of how Mainland children come to know astronomy topics, and with a Western worldview. Research observations of Hawaiian elementary school children indicate that Hawaiian children understand far more about the skies than could have been predicted from the behavior of Mainland children, or from the body of literature on children’s understanding of astronomy. Analysis of elementary students’ responses to a kumu’s, or teacher’s questions relating to the celestial sphere indicate that these students posses a deep knowledge of the night sky and celestial motions. This knowledge base is fluent across two cultural systems of constellations, and is predictive. In an era of curriculum development based upon learning progressions, it appears that Native Hawaiian students possess unexpected knowledge that is well poised to interfere with conventional educational and public outreach approaches if not taken into account. Further, these findings suggest that further inquiry must be made into the astronomical thinking of minority populations prior to the unilateral implementation of national science education standards.

Elliptical instability in stably stratified fluid interiors

NASA Astrophysics Data System (ADS)

Vidal, J.; Hollerbach, R.; Schaeffer, N.; Cebron, D.

2016-12-01

Self-sustained magnetic fields in celestial bodies (planets, moons, stars) are due to flows in internal electrically conducting fluids. These fluid motions are often attributed to convection, as it is the case for the Earth's liquid core and the Sun. However some past or present liquid cores may be stably stratified. Alternative mechanisms may thus be needed to understand the dynamo process in these celestial objects. Turbulent flows driven by mechanical forcings, such as tides or precession, seem very promising since they are dynamo capable. However the effect of density stratification is not clear, because it can stabilize or destabilize mechanically-driven flows.To mimic an elliptical distortion due to tidal forcing in spherical geometry (full sphere and shell), we consider a theoretical base flow with elliptical streamlines and an associated density profile. It allows to keep the numerical efficiency of spectral methods in this geometry. The flow satisfies the stress-free boundary condition. We perform the stability analysis of the base state using three-dimensional simulations to study both the linear and nonlinear regimes. Stable and unstable density profiles are considered. A complementary local stability analysis (WKB) is also performed. We show that elliptical instability can still grow upon a stable stratification. We also study the mixing of the stratification by the elliptical instability. Finally we look at the dynamo capability of these flows.

"The Sky's Things", |xam Bushman 'Astrological Mythology' as recorded in the Bleek and Lloyd Manuscripts

NASA Astrophysics Data System (ADS)

Hollman, J. C.

2007-07-01

The Bleek and Lloyd Manuscripts are an extraordinary resource that comprises some 12 000 pages of |xam Bushman beliefs collected in the 1870s in Cape Town, South Africa. About 17% of the collection concerns beliefs and observations of celestial bodies. This paper summarises |xam knowledge about the origins of the celestial bodies as recorded in the manuscripts and situates this within the larger context of the |xam worldview. The stars and planets originate from a mythological past in which they lived as 'people' who hunted and gathered as the |xam did in the past, but who also had characteristics that were to make them the entities that we recognise today. Certain astronomical bodies have consciousness and supernatural potency. They exert an influence over people's everyday lives.

On some basic principles of the wave planetology illustrated by real shapes and tectonic patterns of celestial bodies

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2011-10-01

The physical background. Celestial bodies move in orbits and keep them due to equality of centrifugal and attractio n forces. These forces are oppositely directed. There is a third force -the inert ia-gravity one directed at the right angle to mentioned above and, thus, not interfering with them (Fig. 1). This force is caused by moving all celestial bodies in non -circular keplerian orbits with periodically changing accelerations. A clear illustration of status of this third force is a stretched rope never achieving a straight line because of the not compensated rope weight acting at the right angle to the stretching force s. In the cas e of cosmic bodies this "not compens ated" inertia-gravity force is absorbed in a cosmic body mass making this mass to warp, undulate. This warping in form of standing waves in rotating bodies is decomposed in four interfering direct ions (ortho - and diagonal) (Fig. 2) producing uplifted (+, ++), subsided (-, --) and neutral (0) blocks (Fig. 2). An interfe rence of fundamental waves 1 long 2π R ma kes always pres ent in bodies tectonic dichotomy: an oppos ition of two hemispheres-segments - one uplifted, another subsided (Fig. 2-6). The first overtone of the wave 1 - wave 2 long πR ma kes tectonic sectors superimposed on segments -hemispheres (Fig. 2, 7, 8). Along with the segment -sectoral pattern in cosmic bodies tectonic granulation develops (Fig. 9, 10). The granule sizes are inversely proportional to orbital frequencies [1-3]. The sectoral tectonic blocks are clearly visible also on Venus and icy satellites of Saturn, especially on polar views. Earth and photosphere are remarkable reference points of this fundamental dependence: orbits - tectonic granulation (Fig. 9, 10).

AstroNavigation: Freely-available Online Instruction for Performing a Sight Reduction

NASA Astrophysics Data System (ADS)

Gessner Stewart, Susan; Grundstrom, Erika; Caudel, Dave

2015-08-01

A reliable method of obtaining your geographic location from observations of celestial bodies is globally available. This online learning module, developed through a collaboration between Vanderbilt University and the U.S. Naval Observatory, serves to address the need for freely-available comprehensive instruction in celestial navigation online. Specifically targeted are the steps of preforming a sight reduction to obtain a terrestrial position using this technique. Difficult concepts such as plotting on a navigational chart and the complexities of using navigation publications are facilitated through this online content delivery, rooted in effective course design principles. There is good potential in using celestial navigation as a tool for stimulating interest in astronomy given its resourcefulness and accessibility.

Tests of the equivalence principle and gravitation theory using solar system bodies

NASA Technical Reports Server (NTRS)

Nordtvedt, K., Jr.

1971-01-01

The M sub g/M sub i ratio (ratio of body acceleration to gravitation field) of celestial bodies was measured. Deep probes of the post-Newtonian structure of gravitational theories are indicated. Kepler's third law is considered for the Sun-Jupiter system.

Tisserand's polynomials and inclination functions in the theory of artificial earth satellites

NASA Astrophysics Data System (ADS)

Aksenov, E. P.

1986-03-01

The connection between Tisserand's polynomials and inclination functions in the theory of motion of artificial earth satellites is established in the paper. The most important properties of these special functions of celestial mechanics are presented. The problem of expanding the perturbation function in satellite problems is discussed.

Elementary Student Knowledge Gains in the Digital Portable Planetarium

ERIC Educational Resources Information Center

Carsten-Conner, Laura D.; Larson, Angela M.; Arseneau, Jennifer; Herrick, Robert R.

2015-01-01

Immersive environments hold promise to provide unique and heightened sensory experiences that focus a learner's attention, and thus may be useful learning platforms. In particular, portable planetariums may be useful in advancing conceptual knowledge about the night sky, because they afford learners with Earth-based views of celestial motions,…

Research in Celestial Mechanics and Differential Equations.

DTIC Science & Technology

Contents: A geopotential representation with sampling functions; Sampling functions as an alternative to spherical harmonics; The Levi - Civita ...restricted problem of three bodies ; Secular perturbations of periodic comets; Resonance in the restricted problem of three bodies ; Two centers of

Special Features of Galactic Dynamics

NASA Astrophysics Data System (ADS)

Efthymiopoulos, Christos; Voglis, Nikos; Kalapotharakos, Constantinos

This is an introductory article to some basic notions and currently open problems of galactic dynamics. The focus is on topics mostly relevant to the so-called `new methods' of celestial mechanics or Hamiltonian dynamics, as applied to the ellipsoidal components of galaxies, i.e., to the elliptical galaxies and to the dark halos and bulges of disk galaxies. Traditional topics such as Jeans theorem, the role of a `third integral' of motion, Nekhoroshev theory, violent relaxation, and the statistical mechanics of collisionless stellar systems are first discussed. The emphasis is on modern extrapolations of these old topics. Recent results from orbital and global dynamical studies of galaxies are then shortly reviewed. The role of various families of orbits in supporting self-consistency, as well as the role of chaos in galaxies, are stressed. A description is then given of the main numerical techniques of integration of the N-body problem in the framework of stellar dynamics and of the results obtained via N-Body experiments. A final topic is the secular evolution and self-organization of galactic systems.

The chaotic "sculpting" of the Solar System

NASA Astrophysics Data System (ADS)

Tsiganis, K.

2006-01-01

The orbits of the large celestial bodies in our Solar System are stable for very long times, as can be shown by numerical simulation. This gives the erroneous impression of perpetual stability of the system. It is only when we study the orbital distribution of the numerous minor bodies in the Solar System that we discover the rich variety of complex dynamical processes that have in fact shaped our system. During the last decade, enormous progress has been made, in understanding the evolution of the system over the last ~3.9 Gy. However, it also became clear that, in order to unveil its behaviour during the first ~700 million years of its lifetime, we have to find convincing explanations for observations that appear as details of its dynamical architecture. In the following we are going to show how the two best known - and up to now unexplained - observations in the Solar System, namely (i) the heavily cratered surface of the Moon and (ii) the elliptic (and not circular) motion of the planets, lead us to the discovery of the chaotic sculpting of the Solar System [1]-[3].

Method based on artificial excitation of characteristic radiation by an electron beam for remote X-ray spectral elemental analysis of surface rocks on atmosphereless celestial bodies

NASA Astrophysics Data System (ADS)

Kolesnikov, E. K.

2016-11-01

This article, like our previous one [1], is devoted to advanced space technology concepts. It evaluates the potential for developing active systems to conduct a remote elemental analysis of surface rocks on an atmosphereless celestial body. The analysis is based on the spectrometry of characteristic X-rays (CXR) artificially excited in the surface soil layer. It has been proposed to use an electron beam injected from aboard a spacecraft orbiting the celestial body (or moving in a flyby trajectory) to excite the CXR elements contained in surface rocks. The focus is on specifying technical requirements to the parameters of payloads for a global mapping of the composition of lunar rocks from aboard of a low-orbiting lunar satellite. This article uses the results obtained in [2], our first study that shows the potential to develop an active system for a remote elemental analysis of lunar surface rocks using the above method. Although there has been interest in our research on the part of leading national academic institutions and space technology developers in the Soviet Union, the studies were discontinued because of the termination of the Soviet lunar program and the completion of the American Apollo program.

Embodying Earth's Place in the Solar System

ERIC Educational Resources Information Center

Plummer, Julia

2015-01-01

Elementary students find it difficult to connect the apparent motion of objects in the sky with how celestial objects actually move in the solar system. As a university astronomy education researcher, the author has been investigating methods to help children learn astronomy through workshops and summer camps at science museums and planetariums.…

Tracking Planets around the Sun

ERIC Educational Resources Information Center

Riddle, Bob

2008-01-01

In earlier columns, the celestial coordinate system of hour circles of right ascension and degrees of declination was introduced along with the use of an equatorial star chart (see SFA Star Charts in Resources). This system shows the planets' motion relative to the ecliptic, the apparent path the Sun follows during the year. An alternate system,…

PERIODIC ORBIT FAMILIES IN THE GRAVITATIONAL FIELD OF IRREGULAR-SHAPED BODIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Yu; Baoyin, Hexi, E-mail: jiangyu_xian_china@163.com

The discovery of binary and triple asteroids in addition to the execution of space missions to minor celestial bodies in the past several years have focused increasing attention on periodic orbits around irregular-shaped celestial bodies. In the present work, we adopt a polyhedron shape model for providing an accurate representation of irregular-shaped bodies and employ the model to calculate their corresponding gravitational and effective potentials. We also investigate the characteristics of periodic orbit families and the continuation of periodic orbits. We prove a fact, which provides a conserved quantity that permits restricting the number of periodic orbits in a fixedmore » energy curved surface about an irregular-shaped body. The collisions of Floquet multipliers are maintained during the continuation of periodic orbits around the comet 1P/Halley. Multiple bifurcations in the periodic orbit families about irregular-shaped bodies are also discussed. Three bifurcations in the periodic orbit family have been found around the asteroid 216 Kleopatra, which include two real saddle bifurcations and one period-doubling bifurcation.« less

Shuttle Orbiter tethered subsatellite for exploring and tapping space plasmas

NASA Technical Reports Server (NTRS)

Banks, P. M.; Williamson, P. R.; Oyama, K. I.

1981-01-01

Consideration is given to the possibilities for studies in space plasma physics offered by a subsatellite mechanically tethered above the Space Shuttle Orbiter by a long conducting wire. The proposed experiment, designated the Shuttle Electrodynamic Tether Systems (SETS) is based on the concept of collecting electrons at the subsatellite and ejecting them from the Orbiter, made possible by the emf generated by the motion of the tether across geomagnetic field lines. The power generated in this manner can be used both for practical purposes within the Orbiter and for the creation of large-amplitude plasma and electromagnetic waves within the surrounding plasma. For a conducting spherical subsatellite 30 m in diameter with a 10-km tether drawing 1 A, calculations show that emfs on the order of 1000-2000 V and energy dissipation of as much as 10,000 W can be obtained, accompanied by the generation of two regions of net electric charge in the ionosphere. Scientific studies considered for SETS include the measurement of MHD waves artificially generated in the ionosphere, the investigation of current-driven plasma instabilities, VLF wave generation and the simulation of electrodynamics associated with the motion of celestial bodies through plasma.

Celestial Treasury

NASA Astrophysics Data System (ADS)

Lachièze-Rey, Marc; Luminet, Jean-Pierre

2001-07-01

Throughout history, the mysterious dark skies have inspired our imaginations in countless ways, influencing our endeavors in science and philosophy, religion, literature, and art. Filled with 380 full-color illustrations, Celestial Treasury shows the influence of astronomical theories and the richness of illustrations in Western civilization through the ages. The authors explore the evolution of our understanding of astronomy and weave together ancient and modern theories in a fascinating narrative. They incorporate a wealth of detail from Greek verse, medieval manuscripts and Victorian poetry with contemporary spacecraft photographs and computer-generated star charts. Celestial Treasury is more than a beautiful book: it answers a variety of questions that have intrigued scientists and laymen for centuries. -- How did philosophers and scientists try to explain the order that governs celestial motion? -- How did geometers and artists measure and map the skies? -- How many different answers have been proposed for the most fundamental of all questions: When and how did Earth come about? -- Who inhabits the heavens--gods, angels or extraterrestrials? No other book recounts humankind's fascination with the heavens as compellingly as Celestial Treasury. Marc Lachièze-Rey is a director of research at the Centre National pour la Récherche Scientifique and astrophysicist at the Centre d'Etudes de Saclay. He is the author of The Cosmic Background Radiation (Cambridge, 1999), and and The Quest for Unity, (Oxford, 1999 ), as well as many books in French. Jean-Pierre Luminet is a research director of the Centre National pour la Rechérche Scientifique, based at the Paris-Meudon observatory. He is the author of Black Holes, (Cambridge 1992), as well as science documentaries for television.

OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Johnston, Helen M.

2013-07-01

Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame.more » We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.« less

Celestial Software Scratches More Than the Surface

NASA Technical Reports Server (NTRS)

2005-01-01

While NASA is preparing to send humans back to the Moon by 2020 and then eventually to Mars, the average person can explore the landscapes of these celestial bodies much sooner, without the risk and training, and without even leaving the comfort of home. Geological data and imagery collected from NASA missions are enabling anybody with computer access to virtually follow the footsteps of Apollo astronauts who walked on the Moon or trace the tracks of the exploration rovers currently on Mars.

Einstein contra Aristotle: The sound from the heavens

NASA Astrophysics Data System (ADS)

Neves, J. C. S.

2017-09-01

In "On the Heavens" Aristotle criticizes the Pythagorean point of view which claims the existence of a cosmic music and a cosmic sound. According to the Pythagorean argument, there exists a cosmic music produced by stars and planets. These celestial bodies generate sound in its movements, and the music appears due to the cosmic harmony. For Aristotle, there is no sound produced by celestial bodies. Then, there is no music as well. However, recently, LIGO (Laser Interferometer Gravitational-Waves Observatory) has detected the gravitational waves predicted by Einstein. In some sense, a sound originated from black holes has been heard. That is, Einstein or the General Relativity and LIGO appear to be with the Pythagoreanism and against the master of the Lyceum.

Different orders of lives in the universe

NASA Astrophysics Data System (ADS)

Sikdar, M. K.

2014-08-01

In this article, main life sensitive elements involved in life creating processes on earth have been explored. An in-depth study has been made to search out material abundances of all life sensitive elements in the periodic table mainly on earth, celestial bodies like star, binary stars, extra-solar system, extra solar planets and galaxies etc. at large. Extensive review has been made to project how life processes are being triggered in our earth and intakes required for continuous metabolism, mutation, reproducibility etc. Finally on the basis of ideas developed about the life processes on earth, other life chains that may happen to exist on other celestial bodies have been predicted. The constraints and barriers that stand in the way of communications have also been pointed out.

Educating astrometry and celestial mechanics students for the 21st century

NASA Astrophysics Data System (ADS)

van Altena, W. F.; Stavinschi, M.

2008-07-01

Astrometry and Celestial Mechanics have entered a new era with the advent of Micro-arcsecond positions, parallaxes and proper motions. Cutting-edge science topics will be addressed that were far beyond our grasp only a few years ago. It will be possible to determine definitive distances to Cepheid variables, the center of our Galaxy, the Magellanic Clouds and other Local Group members. We will measure the orbital parameters of dwarf galaxies that are merging with the Milky Way, define the kinematics, dynamics and structure of our Galaxy and search for evidence of the Dark Matter that makes up most of the mass in the universe. Stellar masses will be determined routinely to 1% accuracy and we will be able to make full orbit solutions and mass determinations for Extrasolar planetary systems. If we are to take advantage of Micro-arcsecond astrometry, we need to reformulate our study of reference frames, systems and the equations of motion in the context of special and general relativity. Methods also need to be developed to statistically analyze our data and calibrate our instruments to levels beyond current standards. As a consequence, our curricula must be drastically revised to meet the needs of students in the 21st Century. With the above considerations in mind, we developed a syllabus for an introductory one-semester course in Astrometry and Celestial Mechanics. This course gives broad introductions to most topics in our fields and a base of knowledge from which a student can elect areas for self-study or attendance at centers where advanced courses, workshops or internships are available.

"Astronomica" in the Correspondence between Leonhard Euler and Daniel Bernoull (German Title: "Astronomica" im Briefwechsel zwischen Leonhard Euler und Daniel Bernoulli)

NASA Astrophysics Data System (ADS)

Verdun, Andreas

2010-12-01

The Euler Commission of the Swiss Academy of Sciences intends to terminate the edition of Leonhard Euler's works in the next year 2011 after nearly one hundred years since the beginning of the editorial works. These works include, e.g., Volume 3 of the Series quarta A which will contain the correspondence between Leonhard Euler (1707-1783) and Daniel Bernoulli (1700-1783) and which is currently being edited by Dr. Emil A. Fellmann (Basel) and Prof. Dr. Gleb K. Mikhailov (Moscow). This correspondence contains more than hundred letters, principally from Daniel Bernoulli to Euler. Parts of this correspondence were published uncommented already in 1843. It is astonishing that, apart from mathematics and physics (mainly mechanics and hydrodynamics), many topics addressed concern astronomy. The major part of the preserved correspondence between Euler and Daniel Bernoulli, in which astronomical themes are discussed, concerns celestial mechanics as the dominant discipline of theoretical astronomy of the eighteenth century. It was triggered and coined mainly by the prize questions of the Paris Academy of Science. In more than two thirds of the letters current problems and questions concerning celestial mechanics of that time are treated, focusing on the lunar theory and the great inequality in the motions of Jupiter and Saturn as special applications of the three body problem. In the remaining letters, problems concerning spherical astronomy are solved and attempts are made to explain certain phenomena in the field of "cosmic physics" concerning astronomical observations.

A new method of intermediate orbit determination based on range and range rate measurements at three times. (Russian Title: Новый метод определения промежуточной орбиты по измерениям дальности и скорости ее изменения в три момента времени)

NASA Astrophysics Data System (ADS)

Shefer, V. A.

2013-12-01

A new method is proposed for computing the preliminary orbit of a small celestial body from three pairs of range and range rate observations. The method is based on using the superosculating intermediate orbit with a fourth-order tangency that we previously constructed. This intermediate orbit allows for most of the perturbations in the motion of the body under study. The methodical error of orbit determination by the proposed method is three orders smaller than the corresponding error of the commonly used approach based on the construction of the unperturbed Keplerian orbit. Using the examples of finding the orbits of artificial Earth satellites, the results obtained by the procedure implementing the traditional approach and the new method are compared. The comparison shows that the new method is a highly efficient means for studying perturbed motion.

Gravitation, Book 3. The University of Illinois Astronomy Program.

ERIC Educational Resources Information Center

Atkin, J. Myron; Wyatt, Stanley P., Jr.

Presented is book three in a series of six books in the University of Illinois Astronomy Program which introduces astronomy to upper elementary and junior high school students. The causes of celestial motion are investigated and the laws that apply to all moving things in the universe are examined in detail. Topics discussed include: the basic…

Brouwer Award Lecture: Anelastic tides of close-in satellites and exoplanets

NASA Astrophysics Data System (ADS)

Ferraz-Mello, Sylvio

2016-05-01

This lecture reviews a new theory of the anelastic tides of celestial bodies in which the deformation of the body is the result of a Newtonian creep inversely proportional to the viscosity of the body and, along each radius, directly proportional to the distance from the actual surface of the body to the equilibrium. The first version of the theory (AAS/DDA 2012; CeMDA 2013), was restricted to homogeneous bodies. It was applied to many different bodies as the Moon, Mercury, super-Earths and hot Jupiters. An improved version (AAS/DDA 2014) included also the loss of angular momentum due to stellar winds and was applied to the study of the rotational evolution of active stars hosting massive companions. One more recent version (Folonier et al. AAS/DDA 2013; DPS 2015) allowed for the consideration of layered structures and was applied to Titan and Mercury. The resulting anelastic tides depend on the nature of the considered body. In the case of low-viscosity bodies (high relaxation factor), as gaseous planets and stars, the results are nearly the same of Darwin's theory. For instance, in these cases the dissipation grows proportionally to the tidal frequency. In the case of high-viscosity rocky satellites and planets (low relaxation factor), the results are structurally different: the dissipation varies with the tidal frequency following an inverse power law and the rotation may be driven to several attractors whose frequencies are 1/2, 1, 3/2, 2, 5/2,… times the orbital mean-motion, even when no permanent triaxiality exists.

Astrometry for Astrophysics

NASA Astrophysics Data System (ADS)

van Altena, William F.

Part I. Astrometry in the Twenty-First Century: 1. Opportunities and challenges for astrometry in the twenty-first century M. Perryman; 2. Astrometric satellites L. Lindegren; 3. Ground-based opportunities for astrometry N. Zacharias; Part II. Relativistic Foundations of Astrometry and Celestial Mechanics: 4. Vectors in astrometry, an introduction L. Lindegren; 5. Relativistic principles of astrometry and celestial mechanics S. Klioner; 6. Celestial mechanics of the N-body problem S. Klioner; 7. Celestial coordinate systems and positions N. Capitaine and M. Stavinschi; 8. Fundamental algorithms for celestial coordinates and positions P. Wallace; Part III. Observing through the Atmosphere: 9. The Earth's atmosphere: refraction, turbulence, delays and limitations to astrometic precision W. van Altena and E. Fomalont; 10. Astrometry with ground-based diffraction-limited imaging A. Ghez; 11. Optical interferometry A. Glindermann; 12. Radio interferometry E. Fomalont; Part VI. From Detected Photons to the Celestial Sphere: 13. Geometrical optics and astrometry D. Schroeder; 14. CCD imaging detectors S. Howell; 15. Using CCDs in the time-delayed integration mode D. Rabinowitz; 16. Statistical astronomy A. Brown; 17. Analyzing poorly-sampled images: HST imaging astrometry J. Anderson; 18. Image deconvolution J. Nuñez; 19. From measures to celestial coordinates Z. H. Tang and W. van Altena; 20. Astrometric catalogs: concepts, history and necessity C. López; 21. Trigonometric parallaxes F. Benedict and B. McArthur; Part V. Applications of Astrometry to Topics in Astrophysics: 22. Galactic structure astrometry R. Méndez; 23. Binary and multiple stars E. Horch; 24. Binaries: HST, Hipparcos and Gaia D. Pourbaix; 25. Star clusters I. Platais; 26. Solar System astrometry F. Mignard; 27. Extrasolar planets A. Sozzetti; 28. Astrometric measurement and cosmology R. Easther; Appendices; Index.

Astrometry for Astrophysics

NASA Astrophysics Data System (ADS)

van Altena, William F.

2012-11-01

Part I. Astrometry in the Twenty-First Century: 1. Opportunities and challenges for astrometry in the twenty-first century M. Perryman; 2. Astrometric satellites L. Lindegren; 3. Ground-based opportunities for astrometry N. Zacharias; Part II. Relativistic Foundations of Astrometry and Celestial Mechanics: 4. Vectors in astrometry, an introduction L. Lindegren; 5. Relativistic principles of astrometry and celestial mechanics S. Klioner; 6. Celestial mechanics of the N-body problem S. Klioner; 7. Celestial coordinate systems and positions N. Capitaine and M. Stavinschi; 8. Fundamental algorithms for celestial coordinates and positions P. Wallace; Part III. Observing through the Atmosphere: 9. The Earth's atmosphere: refraction, turbulence, delays and limitations to astrometic precision W. van Altena and E. Fomalont; 10. Astrometry with ground-based diffraction-limited imaging A. Ghez; 11. Optical interferometry A. Glindermann; 12. Radio interferometry E. Fomalont; Part VI. From Detected Photons to the Celestial Sphere: 13. Geometrical optics and astrometry D. Schroeder; 14. CCD imaging detectors S. Howell; 15. Using CCDs in the time-delayed integration mode D. Rabinowitz; 16. StaStatistical astronomy A. Brown; 17. Analyzing poorly-sampled images: HST imaging astrometry J. Anderson; 18. Image deconvolution J. Nuñez; 19. From measures to celestial coordinates Z. H. Tang and W. van Altena; 20. Astrometric catalogs: concepts , history and necessity C. Löpez; 21. Trigonometric parallaxes F. Benedict and B. McArthur; Part V. Applications of Astrometry to Topics in Astrophysics: 22. Galactic structure astrometry R. Méndez; 23. Binary and multiple stars E. Horch; 24. Binaries: HST, Hipparcos and Gaia D. Pourbaix; 25. Star clusters I. Platais; 26. Solar System astrometry F. Mignard; 27. Extrasolar planets A. Sozzetti; 28. Astrometric measurement and cosmology R. Easther; Appendices; Index.

The discovery of silicon oxide nanoparticles in space-weathered of Apollo 15 lunar soil grains

NASA Astrophysics Data System (ADS)

Gu, Lixin; Zhang, Bin; Hu, Sen; Noguchi, Takaaki; Hidaka, Hiroshi; Lin, Yangting

2018-03-01

Space weathering is an important process on the Moon and other airless celestial bodies. The most common space weathering effects are amorphization of the top surface of soil grains and formation of nanophase iron particles (npFe) within the partially amorphous rims. Hence, space weathering significantly affects optical properties of the surface of the Moon and other airless celestial bodies. Transmission electron microscope (TEM) analysis of Apollo 15 soil grains displays npFe (≤5 nm in size) embedded in the space-weathered rim (∼60 nm in thickness) of a pyroxene grain, consistent with previous studies. In contrast, submicron-sized fragments that adhere to the pyroxene grain show distinct space weathering features. Silicon oxide nanoparticles (npSiOx) were observed with npFe in a submicron-sized Mg-Fe silicate fragment. This is the first discovery of npSiOx as a product of space weathering. The npSiOx and the coexisting npFe are ∼10-25 nm in size, significantly larger than the typical npFe in the space weathered rim of the pyroxene grain. The coexisting npSiOx and npFe were probably formed directly in micrometeorite shock-induced melt, instead of in a solar-wind generated vapor deposit or irradiated rim. This new observation will shed light on space weathering processes on the Moon and airless celestial bodies.

Development and validation of a learning progression for change of seasons, solar and lunar eclipses, and moon phases

NASA Astrophysics Data System (ADS)

Testa, Italo; Galano, Silvia; Leccia, Silvio; Puddu, Emanuella

2015-12-01

In this paper, we report about the development and validation of a learning progression about the Celestial Motion big idea. Existing curricula, research studies on alternative conceptions about these phenomena, and students' answers to an open questionnaire were the starting point to develop initial learning progressions about change of seasons, solar and lunar eclipses, and Moon phases; then, a two-tier multiple choice questionnaire was designed to validate and improve them. The questionnaire was submitted to about 300 secondary students of different school levels (14 to 18 years old). Item response analysis and curve integral method were used to revise the hypothesized learning progressions. Findings support that spatial reasoning is a key cognitive factor for building an explanatory framework for the Celestial Motion big idea, but also suggest that causal reasoning based on physics mechanisms underlying the phenomena, as light flux laws or energy transfers, may significantly impact a students' understanding. As an implication of the study, we propose that the teaching of the three discussed astronomy phenomena should follow a single teaching-learning path along the following sequence: (i) emphasize from the beginning the geometrical aspects of the Sun-Moon-Earth system motion; (ii) clarify consequences of the motion of the Sun-Moon-Earth system, as the changing solar radiation flow on the surface of Earth during the revolution around the Sun; (iii) help students moving between different reference systems (Earth and space observer's perspective) to understand how Earth's rotation and revolution can change the appearance of the Sun and Moon. Instructional and methodological implications are also briefly discussed.

Record-Breaking Radio Astronomy Project to Measure Sky with Extreme Precision

NASA Astrophysics Data System (ADS)

2009-11-01

Astronomers will tie together the largest collection of the world's radio telescopes ever assembled to work as a single observing tool in a project aimed at improving the precision of the reference frame scientists use to measure positions in the sky. The National Science Foundation's Very Long Baseline Array (VLBA) will be a key part of the project, which is coordinated by the International VLBI Service for Geodesy and Astrometry. For 24 hours, starting Wednesday, November 18, and ending Thursday, November 19, 35 radio telescopes located on seven continents will observe 243 distant quasars. The quasars, galaxies with supermassive black holes at their cores, are profuse emitters of radio waves, and also are so distant that, despite their actual motions in space, they appear stationary as seen from Earth. This lack of apparent motion makes them ideal celestial landmarks for anchoring a grid system, similar to earthly latitude and longitude, used to mark the positions of celestial objects. Data from all the radio telescopes will be combined to make them work together as a system capable of measuring celestial positions with extremely high precision. The technique used, called very long baseline interferometry (VLBI), has been used for decades for both astronomical and geodetic research. However, no previous position-measuring observation has used as many radio telescopes or observed as many objects in a single session. The previous record was a 23-telescope observation. At a meeting in Brazil last August, the International Astronomical Union adopted a new reference frame for celestial positions that will be used starting on January 1. This new reference frame uses a set of 295 quasars to define positions, much like surveyor's benchmarks in a surburban subdivision. Because even with 35 radio telescopes around the world, there are some gaps in sky coverage, the upcoming observation will observe 243 of the 295. By observing so many quasars in a single observing session, problems of linking positions from one observing session to another can be avoided, the astronomers say. The result will be a much stronger, more precise, reference grid. Telescopes in Asia, Australia, Europe, North America, South America, Antarctica, and in the Pacific will participate. Improving the celestial positional grid will allow astronomers better to pinpoint the locations and measure the motions of objects in the sky. As astronomers increasingly study objects using multiple telescopes observing at different wavelengths, such as visible light, radio, infrared, etc., the improved positional grid will allow more accurate overlaying of the different images. The improved celestial reference frame also strengthens a terrestrial reference frame used for radio-telescope measurements that contribute to geophysical research. The precise geodetic measurements help geophysicists understand phenomena such as plate tectonics, earth tides, and processes that affect our planet's orientation in space. The VLBA is a continent-wide radio telescope system with 10, 240-ton dish antennas ranging from Hawaii to the Virgin Islands. Operated from the National Radio Astronomy Observatory's Pete V. Domenici Science Operations Center in Socorro, New Mexico, the VLBA offers the greatest resolving power, or ability to see fine detail, of any telescope in astronomy. The multi-telescope observation will be accompanied by public-outreach activities in celebration of the International Year of Astronomy. A public web page devoted to the observation will be hosted at Bordeaux Observatory, and some of the participating telescopes will have webcams available.

The General History of Astronomy

NASA Astrophysics Data System (ADS)

Taton, René; Wilson, Curtis; Hoskin, editor Michael, , General

2009-09-01

Part V. Early Phases in the Reception of Newton's Theory: 14. The vortex theory in competition with Newtonian celestial dynamics Eric J. Aiton; 15. The shape of the Earth Seymour L. Chapin; 16. Clairaut and the motion of the lunar apse: The inverse-square law undergoes a test Craig B. Waff; 17. The precession of the equinoxes from Newton to d'Alembert and Euler Curtis Wilson; 18. The solar tables of Lacaille and the lunar tables of Mayer Eric G. Forbes and Curtis Wilson; 19. Predicting the mid-eighteenth-century return of Halley's Comet Craig B. Waff; Part VI. Celestial Mechanics During the Eighteenth Century: 20. The problem of perturbation analytically treated: Euler, Clairaut, d'Alembert Curtis Wilson; 21. The work of Lagrange in celestial mechanics Curtis Wilson; 22. Laplace Bruno Morando; Part VII. Observational Astronomy and the Application of Theory in the Late Eighteenth and Early Nineteenth Century: 23. Measuring solar parallax: The Venus transits of 1761 and 1769 and their nineteenth-century sequels Albert Van Helden; 24. The discovery of Uranus, the Titius-Bode and the asteroids Michael Hoskin; 25. Eighteenth-and nineteenth century developments in the theory and practice of orbit determination Brian G. Marsden; 26. The introduction of statistical reasoning into astronomy: from Newton to Poincaré Oscar Sheynin; 27. Astronomy and the theory of errors: from the method of averages to the method of least squares F. Schmeidler; Part VIII. The Development of Theory During the Nineteenth Century: 28. The golden age of celestial mechanics Bruno Morando; Part IX. The Application of Celestial Mechanics to the Solar System to the End of the Nineteenth Century: 29. Three centuries of lunar and planetary ephemerides and tables Bruno Morando; 30. Satellite ephemerides to 1900 Yoshihide Kozai; Illustrations; Combined index for Parts 2A and 2B.

Concise CIO based precession-nutation formulations

NASA Astrophysics Data System (ADS)

Capitaine, N.; Wallace, P. T.

2008-01-01

Context: The IAU 2000/2006 precession-nutation models have precision goals measured in microarcseconds. To reach this level of performance has required series containing terms at over 1300 frequencies and involving several thousand amplitude coefficients. There are many astronomical applications for which such precision is not required and the associated heavy computations are wasteful. This justifies developing smaller models that achieve adequate precision with greatly reduced computing costs. Aims: We discuss strategies for developing simplified IAU 2000/2006 precession-nutation procedures that offer a range of compromises between accuracy and computing costs. Methods: The chain of transformations linking celestial and terrestrial coordinates comprises frame bias, precession-nutation, Earth rotation and polar motion. We address the bias and precession-nutation (NPB) portion of the chain, linking the Geocentric Celestial Reference System (GCRS) with the Celestial Intermediate Reference System (CIRS), the latter based on the Celestial Intermediate Pole (CIP) and Celestial Intermediate Origin (CIO). Starting from direct series that deliver the CIP coordinates X,Y and (via the quantity s + XY/2) the CIO locator s, we look at the opportunities for simplification. Results: The biggest reductions come from truncating the series, but some additional gains can be made in the areas of the matrix formulation, the expressions for the nutation arguments and by subsuming long period effects into the bias quantities. Three example models are demonstrated that approximate the IAU 2000/2006 CIP to accuracies of 1 mas, 16 mas and 0.4 arcsec throughout 1995-2050 but with computation costs reduced by 1, 2 and 3 orders of magnitude compared with the full model. Appendices A to G are only available in electronic form at http://www.aanda.org

Spacetime Dynamics and Slow Neutrino Background

NASA Astrophysics Data System (ADS)

Zhang, Tianxi

2018-06-01

Space is a form of existence of matter, while time is a measure of change of the matter in the space. Issac Newton suggested that the space and time are absolute, not affected by matter and its motion. His first law of motion or the law of inertia says that, without net force acts on it, an object in motion remains the motion in a straight line at a constant speed. Ernest Mach proposed that the inertia of a body results from the gravitational interaction on the body by the rest of the entire universe. As mass is a measure of inertia, Mach’s principle can be simply stated as mass here is affected by matter there. On the basis of Mach’s principle, Albert Einstein considered the space and time to be relative and developed two theories of relativities. One called special relativity describes the effect of motion on spacetime and the other called general relativity describes the effect of matter on spacetime. Recently, the author has further considered reactions of the influenced spacetime on the moving objects, including photons. A moving object including a photon, because of its continuously keeping on displacement, disturbs the rest of the entire universe or distorts/curves the spacetime. The distorted or curved spacetime then generates an effective gravitational force to act back on the moving object or photon, so that reduces the object inertia or photon frequency. Considering the disturbance of spacetime by a photon is extremely weak, the author has modelled the effective gravitational force to be Newtonian and derived a new redshift-distance relation that not only perfectly explained the redshift-distance measurement of distant type Ia supernovae but also inherently obtained Hubble’s law as an approximate at small redshift. In this study, we will further analyse the reaction of the influenced spacetime on moving neutrinos and demonstrate the creation of slow neutrino (or tired neutrino) background that may be gravitationally orbiting around clusters, galaxies, and any celestial objects to play a role of dark mater in explaining the excess of galactic and clustery rotations. This work was supported by NSF/REU (Grant #: PHY-1559870) at Alabama A & M University.

The periodic dynamics of the irregular heterogeneous celestial bodies

NASA Astrophysics Data System (ADS)

Lan, Lei; Yang, Mo; Baoyin, Hexi; Li, Junfeng

2017-02-01

In this paper, we develop a methodology to study the periodic dynamics of irregular heterogeneous celestial bodies. Heterogeneous bodies are not scarce in space. It has been found that bodies, such as 4 Vesta, 624 Hektor, 87 Sylvia, 16 Psyche and 25143 Itokawa, may all have varied internal structures. They can be divided into large-scale and small-scale cases. The varied internal structures of large-scale bodies always result from gradient pressure inside, which leads to compactness differences of the inner material. However, the heterogeneity of a small-scale body is always reflected by the different densities of different areas, which may originate from collision formation from multiple objects. We propose a modeling procedure for the heterogeneous bodies derived from the conventional polyhedral method and then compare its dynamical characteristics with those of the homogeneous case. It is found that zero-velocity curves, positions of equilibrium points, types of bifurcations in the continuation of the orbital family and the stabilities of periodic orbits near the heterogeneous body are different from those in the homogeneous case. The suborbicular orbits near the equatorial plane are potential parking orbits for a future mission, so we discuss the switching of the orbital stability of the family because it has fundamental significance to orbit maintenance and operations around actual asteroids.

A diamond in the sky: an exclusion or normal situation?

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2009-04-01

A diamond in the sky: an exclusion or normal situation? G. Kochemasov IGEM of the Russian Academy of Sciences, Moscow, Russia, kochem.36@mail.ru The September 2008 observation and imaging by the ESA-"Rosetta" spacecraft of the small asteroid (2867) Steins should have a rather deep impact at planetological thinking. The planetology community is accustomed to think that the only process making forms of small bodies is the impact (accretion) process. No other forces are considered as though there is none. But actually there is one mighty process - a wave process that affects all cosmic bodies by warping them in several (normally four) directions. An origin of these warping waves is quite simple. All cosmic bodies move (orbit) and rotate. After I. Kepler we know that all orbits are non-round but elliptical (time rounds them but ellipticity always remain), and this means that orbiting bodies periodically cyclically change their accelerations (speeding up and slowing down). Multiplied by masses these changes produce forces applied to the bodies and causing oscillations of their spheres. In rotating bodies (but all bodies rotate!) these oscillations are decomposed (split) into four orthogonal and diagonal directions. Interfering of these directions produces uplifting, subsiding and neutral tectonic blocks which are observed on any celestial body more or less clearly. The blocks dimensions depend on lengths of warping waves that acquire a stationary character in closed spheres. That is why celestial spheres are not like billiards-balls but consist of regularly placed depressions (lowlands) and highlands. The longest fundamental wave 1 produces ubiquitous tectonic dichotomy - an opposition of subsided and bulged hemispheres (segments). The Plato's tetrahedron is a structural expression of this configuration: in this simplest polyhedron there is an opposition of a vertex (bulging, extension) and a face (pressing in, contraction). A convexo-concave shape of small bodies is very typical [1]; in some viewpoints they look as tetrahedrons [2]. The first overtone of the fundamental wave - wave 2 - produces structural octahedron (diamond). Rarely in a full shape, more often in its parts {rectilinear crossing outlines) this shape is rather typical in many obtained images of small bodies [3]. Not perfection of this polyhedron in reality is due to its superposition on a tetrahedron structure and complication by wave structures of the lower ranges, like a cube, dodecahedron, and impacts. Still, in some cases "diamond" in the sky is rather clear - Yanus (PIA 06613), Steins. Dr. Schwehm's prediction of even larger asteroid "diamond' in shape of Lutetia is really significant [4]. If small bodies are able to demonstrate their natural polyhedron shapes due to negligible gravity, the larger bodies are reduced to a globe shape by a mighty gravity. Still their structural layout (ubiquitous dichotomy), some protruding vertices, edges and faces betray their polyhedron nature. In this relation, "mysterious" Saturn's northern hexagon is a reflection of three crossing tetrahedron faces making the fourth face, while the southern hurricane is an imprint of an opposite vertex. Thus looks a hidden polyhedron in a globe. ESA-Rosetta mission is a real clue to an adequate understanding, deciphering forces sculpturing celestial bodies. Images of asteroid Steins revealing its clear polyhedron (diamond) shape witness to an involvement of warping wave processes. References: [1] Kochemasov G.G. (1999) On convexo-concave shape of small celestial bodies // "Asteroids, Comets, Meteors" conference, Cornell Univ., U.S.A., July 1999, Abstract # 24. 22; [2] Kochemasov G.G. (2008) Plato' polyhedra as shapes of small icy satellites // Geophys. Res. Abstracts, Vol. 10, EGU2008-A-01271, CD-ROM ; [3] Kochemasov G.G. (1999) "Diamond" and "dumb-bells"-like shapes of celestial bodies induced by inertia-gravity waves // 30th Vernadsky-Brown microsymposium on comparative planetology, Abstracts, Moscow, Vernadsky Inst.,, 49-50; [4] ESA News. Steins: a diamond in the sky, 6 September, 2008 (http://www.esa.int/rosetta);

Development and Validation of a Learning Progression for Change of Seasons, Solar and Lunar Eclipses, and Moon Phases

ERIC Educational Resources Information Center

Testa, Italo; Galano, Silvia; Leccia, Silvio; Puddu, Emanuella

2015-01-01

In this paper, we report about the development and validation of a learning progression about the Celestial Motion big idea. Existing curricula, research studies on alternative conceptions about these phenomena, and students' answers to an open questionnaire were the starting point to develop initial learning progressions about change of seasons,…

Learning to Explain Astronomy across Moving Frames of Reference: Exploring the Role of Classroom and Planetarium-Based Instructional Contexts

ERIC Educational Resources Information Center

Plummer, Julia Diane; Kocareli, Alicia; Slagle, Cynthia

2014-01-01

Learning astronomy involves significant spatial reasoning, such as learning to describe Earth-based phenomena and understanding space-based explanations for those phenomena as well as using the relevant size and scale information to interpret these frames of reference. This study examines daily celestial motion (DCM) as one case of how children…

Computational complexity in entanglement transformations

NASA Astrophysics Data System (ADS)

Chitambar, Eric A.

In physics, systems having three parts are typically much more difficult to analyze than those having just two. Even in classical mechanics, predicting the motion of three interacting celestial bodies remains an insurmountable challenge while the analogous two-body problem has an elementary solution. It is as if just by adding a third party, a fundamental change occurs in the structure of the problem that renders it unsolvable. In this thesis, we demonstrate how such an effect is likewise present in the theory of quantum entanglement. In fact, the complexity differences between two-party and three-party entanglement become quite conspicuous when comparing the difficulty in deciding what state changes are possible for these systems when no additional entanglement is consumed in the transformation process. We examine this entanglement transformation question and its variants in the language of computational complexity theory, a powerful subject that formalizes the concept of problem difficulty. Since deciding feasibility of a specified bipartite transformation is relatively easy, this task belongs to the complexity class P. On the other hand, for tripartite systems, we find the problem to be NP-Hard, meaning that its solution is at least as hard as the solution to some of the most difficult problems humans have encountered. One can then rigorously defend the assertion that a fundamental complexity difference exists between bipartite and tripartite entanglement since unlike the former, the full range of forms realizable by the latter is incalculable (assuming P≠NP). However, similar to the three-body celestial problem, when one examines a special subclass of the problem---invertible transformations on systems having at least one qubit subsystem---we prove that the problem can be solved efficiently. As a hybrid of the two questions, we find that the question of tripartite to bipartite transformations can be solved by an efficient randomized algorithm. Our results are obtained by encoding well-studied computational problems such as polynomial identity testing and tensor rank into questions of entanglement transformation. In this way, entanglement theory provides a physical manifestation of some of the most puzzling and abstract classical computation questions.

Book Review: Precession, Nutation, and Wobble of the Earth

NASA Astrophysics Data System (ADS)

Sterken, Christiaan; Dehant, V.; Mathews, P. M.

2016-10-01

This great book describes and explains observational and computational aspects of three apparently tiny changes in the Earth's motion and orientation, viz., precession, nutation, and wobble. The three introductory chapters of this book present fundamental definitions, elementary geodetic theory, and celestial/terrestrial reference systems - including transformations between reference frames. The next chapter on observational techniques describes the principle of accurate measurements of the orientation of the Earth's axis, as obtained from measurements of extra-galactic radio sources using Very Long Baseline Interferometry and GPS observations. Chapter 5 handles precession and nutation of the rigid Earth (i.e., a celestial body that cannot, by definition, deform) and the subsequent chapter takes deformation into consideration, viz., the effect of a centrifugal force caused by a constant-rate rotation that causes the Earth's shape and structure to become ellipsoidal. Deformations caused by external solar-system bodies are discussed in terms of deformability parameters. The next three chapters handle additional complex deviations: non-rigid Earth and more general Earth models, anelastic Earth parameters, and the effects of the fluid layers (i.e., ocean and atmosphere) on Earth rotation. Chapter 10 complements Chapter 7 with refinements that take into account diverse small effects such as the effect of a thermal conductive layer at the top of the core, Core Mantle and Inner Boundary coupling effects on nutation, electromagnetic coupling, and so-called topographic coupling. Chapter 11 covers comparison of observation and theory, and tells us that the present-date precision of the nutation theory is at the level of milliarcseconds in the time domain, and of a tenth of a microsecond in the frequency domain (with some exceptions). This chapter is followed by a 25-page chapter of definitions of equator, equinox, celestial intermediate pole and origin, stellar angle, universal time, and more. Chapter 13 treats the planet Mars, as it is also rapidly rotating, has an equatorial bulge and an obliquity that is comparable to that of the Earth. The last chapter is followed by three Appendices, viz., Rotation representation, Clairaut theory and Definitions of equinoxes. Appendix A deals with rotation vector and rotation matrix, specifically applied to small angles, such as in the case of rotation from change of pole position. Appendix B expresses the Earth's gravitational potential, and the first-order hypothesis that the Earth is in hydrostatic equilibrium, and that its uniformly-rotating surface is an equipotential corresponding to the mean sea level. Appendix C presents a set of definitions of equinoxes. This book is extremely well documented with more than 50 pages of references that are very up to date. The illustrations (exclusively line art diagrams) are all of good quality and the data tables are rich and well formatted. The language is clear and direct, but with nearly 1500 mathematical formulae, this reference work primarily appeals to the community of mathematically-schooled researchers, although anyone lecturing or teaching in celestial mechanics will see this jewel as a treasure trove to be visited on.

White Dwarfs, Neutron Stars and Black Holes

ERIC Educational Resources Information Center

Szekeres, P.

1977-01-01

The three possible fates of burned-out stars: white dwarfs, neutron stars and black holes, are described in elementary terms. Characteristics of these celestial bodies, as provided by Einstein's work, are described. (CP)

Antikythera Calculator advances modern science of 19 centuries

NASA Astrophysics Data System (ADS)

Pastore, Giovanni

2010-08-01

The Greek astronomic calculator, discovered in the depth of the sea in a naval wreckage of the 1st century B.C. in front of the island of Antikythera, is the most amazing among the archaeological discoveries of last century. The mechanism immediately appeared like a device out of its time. After years of study this devise is still provoking a discussion between scientists and archaeologists because of the complexity and the modernity of the scientific knowledge the work presupposes. Its epicyclical gearings show the high level of the scientific culture reached in that period of history. The knowledge of the planetary motion, necessary to the design of the epicyclic gearing of the Calculator of Antikythera, presumes that ancient Greek scientists knew the planetary motion of the celestial bodies and had already achieved the same results that have been attributed to scientists 19 centuries later. The scientific value of this gear mechanism is indisputable because the inventor of the Calculator of Antikythera had the knowledge that was "re-discovered" centuries later as the heliocentric theory proposed by Niccolò Copernicus in 1543 ( De revolutionibus orbium coelestium), the universal gravitation law formulated by Isaac Newton in 1687 ( Philosophiae Naturalis Principia Mathematica), and the kinematic study of the epicyclical gearings published by Robert Willis in 1841 ( Principles of mechanism).

Apollo 13 - Prime Crew Portrait

NASA Image and Video Library

1969-12-11

S69-62224 (December 1969) --- The members of the prime crew of the Apollo 13 lunar landing mission (left to right) are astronauts James A. Lovell Jr., commander; Thomas K. Mattingly II, command module pilot; and Fred W. Haise Jr., lunar module pilot. They are seated in front of a scene of the Lagoon Nebula, with the mission insignia and two items of early navigation in the foreground. Represented in the Apollo 13 emblem (center) is Apollo, the sun god of Greek mythology, symbolizing that the Apollo flights have extended the light of knowledge to all mankind. The Latin phrase Ex Luna, Scientia means "From the Moon, Knowledge." The Hindu astrolabe in Sanskrit (on right) was used to predict the position of celestial bodies before the invention of the octant (on left) was used in 1790 to determine the altitude of celestial bodies from aboard ship.

On the Hipparcos Link to the ICRF derived from VLA and MERLIN radio astrometry

NASA Astrophysics Data System (ADS)

Hering, R.; Walter, H. G.

2007-06-01

Positions and proper motions obtained from observations by the very large array (VLA) and the multi-element radio-linked interferometer network (MERLIN) are used to establish the link of the Hipparcos Celestial Reference Frame (HCRF) to the International Celestial Reference Frame (ICRF). The VLA and MERLIN data are apparently the latest ones published in the literature. Their mean epoch at around 2001 is about 10 years after the epoch of the Hipparcos catalogue and, therefore, the data are considered suitable to check the Hipparcos link established at epoch 1991.25. The parameters of the link, i.e., the angles of frame orientation and the angular rates of frame rotation, are estimated by fitting these parameters to the differences of the optical and radio positions and proper motions of stars common to the Hipparcos catalogue and the VLA and MERLIN data. Both the estimates of the angles of orientation and the angular rates of rotation show nearly consistent but insignificant results for all samples of stars treated. We conclude that not only the size of the samples of 9 15 stars is too small, but also that the accuracy of the radio positions and, above all, of the radio proper motions is insufficient, the latter being based on early-epoch star positions of low accuracy. The present observational data at epoch 2001 suggest that maintenance of the Hipparcos frame is not feasible at this stage.

On the Late Development and Possible Astronomical Origin of the Gyroscope

NASA Astrophysics Data System (ADS)

Brecher, Kenneth

2013-01-01

The invention of the gyroscope is usually attributed to the French physicist Jean-Bernard-Leon Foucault in the year 1852. He certainly created the word and also used his gyroscope to demonstrate the rotation of the Earth. However, the gyroscope was actually invented around 1812 by the German scientist Johann Bohnenberger who called his device simply the “machine”. Bohnenberger was a professor of astronomy and mathematics and published a book about astronomy in 1811. Several other scientists, including American physicist Walter R. Johnson (who called his apparatus the “rotascope”), independently invented the gyroscope. Each of these devices employed a central object (sphere or disc) that could spin on a shaft. This object was placed between three independent gimbals, two of which could move freely. Bohnenberger’s “machine” has much the same appearance as an armillary sphere. Those astronomical devices had been produced for at least the preceding three centuries and were widely dispersed and well known throughout Europe. They were used to display the apparent motion of celestial bodies. However, armillary spheres were used only as simulations of celestial appearances, not as actual demonstrations of physical phenomena. It is not known if the inertial properties of armillary spheres (and also of terrestrial and celestial globes) had been studied before about 1800. Nonetheless, as a matter of practice, gimbal systems similar to those found in gyroscopes were used on ships to level oil lamps at least as early as the sixteenth century AD. And the ideas behind armillary spheres date back at least a millennium before that. So why did the invention of the gyroscope in its modern form take such a long time when the individual underlying components had been around and utilized for some two millennia? Perhaps because the understanding of angular momentum, including its conservation, was not developed until the start of the 19th century and also because the technologies necessary to make practical gyroscopes were only developed later in the 19th century. This study was supported in part by NSF Grant # DUE-0715975 for Project LITE.

Observations of Anomalous Refraction with Co-housed Telescopes

NASA Astrophysics Data System (ADS)

Taylor, Malinda S.; McGraw, J. T.; Zimmer, P. C.

2013-01-01

Anomalous refraction is described as a low frequency, large angular scale motion of the entire image plane with respect to the celestial coordinate system as observed and defined by previous astrometric catalogs. These motions of typically several tenths of an arcsecond with timescales on the order of ten minutes are ubiquitous to drift-scan ground-based astrometric measurements regardless of location or telescopes used and have been attributed to meter scale slowly evolving coherent dynamical structures in the boundary-layer below 60 meters. The localized nature of the effect and general inconsistency of the motions seen by even closely spaced telescopes in individual domes has led to the hypothesis that the dome or other type of telescope housing may be responsible. This hypothesis is tested by observing anomalous refraction using two telescopes housed in a single roll-off roof observatory building with the expected outcome that the two telescopes will see correlated anomalous refraction induced motions.

The Concise Knowledge Astronomy

NASA Astrophysics Data System (ADS)

Clerke, Agnes Mary; Fowler, Alfred; Ellard Gore, John

2011-01-01

Preface; Section I. History Agnes M. Clerke: 1. From Hipparchus to Laplace; 2. A century of progress; Section II. Geometrical Astronomy and Astronomical Instruments A. Fowler: 1. The Earth and its rotation; 2. The Earth's revolution round the Sun; 3. How the positions of the heavenly bodies are defined; 4. The Earth's orbit; 5. Mean solar time; 6. The movements of the Moon; 7. Movements of planets, satellites, and comets; 8. Eclipses and occultations; 9. How to find our situation on the Earth; 10. The exact size and shape of the earth; 11. The distances and dimensions of the heavenly bodies; 12. The masses of celestial bodies; 13. Gravitational effects of Sun and moon upon the Earth; 14. Instrumental measurement of angles and time; 15. Telescopes; 16. Instruments of precision; 17. Astrophysical instruments; Section III. The Solar System Agnes M. Clerke: 1. The solar system as a whole; 2. The Sun; 3. The Sun's surroundings; 4. The interior planets; 5. The Earth and Moon; 6. The planet Mars; 7. The asteroids; 8. The planet Jupiter; 9. The Saturnian system; 10. Uranus and Neptune; 11. Famous comets; 12. Nature and origin of comets; 13. Meteorites and shooting stars; Section IV. The Sidereal Heavens J.E. Gore: 1. The stars and constellations; 2. Double, multiple, and coloured stars; 3. The distances and motions of the stars; 4. Binary stars; 5. Variable and temporary stars; 6. Clusters and nebulae; 7. The construction of the heavens; Index.

Animation Sequence of Comet Wild2 Once More Demonstrates Shape Peculiarities of Small Celestial Bodies

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

The outstanding success of the Stardust mission having acquired in January 2004 images of Comet Wild2 allows us to compare them with images of some other small objects: satellites, asteroids, comets and confirm the earlier conclusion about prevailing shaping forces [1, 2]. The excellent images of the Comet Wild2 core (the best up to date among comets, Internet) show that it is not ``a ball of dirty ice and rock'' but rather a convexo-concave object resembling other small bodies. They all, independently of their nature, sizes, compositions, demonstrate oblong ``banana''-type style. This is a result of pressing in one side and bulging out another antipodean one (the fundamental wave action). Comet Wild2 (5.4 km long core) in this sense can be perfectly compared with asteroid Mathilde (60 km) and satellite Thebe (˜ 116 km). All three have deeply concave hemisphere opposed by clearly convex one. Bulging out friable material often induces deep fracturing of convex hemispheres. This is well visible in comet Borrelli (8 km long core) and especially pronounced in asteroids Eros (33 km) and Annefrank (`˜ 6 km). Deep ``saddle'' at the convex side of both makes their images rather similar. Another characteristic of small oblong bodies is a principal shape difference of two elongated ends: one is blunt, another sharp. Principally, it is the same process which makes the ``banana''-shape (wave1) but of a smaller scale (wave2). The blunt end is made by pressing in, the sharp end by bulging out. Obviously, an impact sculpturing cannot give similar complex forms in so different bodies. The main principal shaping is done by standing inertia-gravity waves arising in celestial bodies in response to their movement in elliptical orbits with periodically changing accelerations. The fundamental wave1 makes convexo-concave shape, the first overtone wave2 sharp-blunt ends. Larger celestial bodies: satellites, planets, stars react to these waves by universal tectonic dichotomy and sectoring [3]. The arctic-antarctic symptom (after Earth) is typical manifestation of sectoring with two antepodean sectors: one pressed in, another bulged out. References: [1] Kochemasov G.G. (1999) On convexo-concave shape of small celestial bodies // ``Asteroids, Comets, Meteors'' conference, Cornell Univ., U.S.A., July 1999, Abstract # 24. 22; [2] Kochemasov G.G. (2002) ``Dirty snowball'' -- now is too primitive for a scientific description of comets // 34th COSPAR Scientific Assembly at the World Space Congress 2002, 10-19 Oct. 2002, Houston, Texas, USA, (CD-ROM); [3] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., Vol. 1, # 3, 700.

Kepler, the Ultimate Aristotelian

NASA Astrophysics Data System (ADS)

Davis, A. E. L.

A comparison is made between Aristotelian and Newtonian versions of Laws of Motion. Kepler was successful in proving the 2 laws of motion of a single planet - to the extent that agreement with a framework of theory constitutes a proof. Of course he invented his framework of causes after the event, to fit the motions that had been already been quantified - but it may seem to you that Kepler's mainly mechanistic way explanation could have been considered by his contemporaries just as reasonable as Newton's action at a distance. It could be now apprecated that there was a window of less than 50 years before Newton's total synthesis. No-one previously had had the motivation to create a system of "celestial physics" based on a judicious use of Aristotelian principles. Yet this is what Kepler achieved.

Space Toxicology: Human Health during Space Operations

NASA Technical Reports Server (NTRS)

Khan-Mayberry, Noreen; James, John T.; Tyl, ROchelle; Lam, Chiu-Wing

2010-01-01

Space Toxicology is a unique and targeted discipline for spaceflight, space habitation and occupation of celestial bodies including planets, moons and asteroids. Astronaut explorers face distinctive health challenges and limited resources for rescue and medical care during space operation. A central goal of space toxicology is to protect the health of the astronaut by assessing potential chemical exposures during spaceflight and setting safe limits that will protect the astronaut against chemical exposures, in a physiologically altered state. In order to maintain sustained occupation in space on the International Space Station (ISS), toxicological risks must be assessed and managed within the context of isolation continuous exposures, reuse of air and water, limited rescue options, and the need to use highly toxic compounds for propulsion. As we begin to explore other celestial bodies in situ toxicological risks, such as inhalation of reactive mineral dusts, must also be managed.

A novel interplanetary optical navigation algorithm based on Earth-Moon group photos by Chang'e-5T1 probe

NASA Astrophysics Data System (ADS)

Bu, Yanlong; Zhang, Qiang; Ding, Chibiao; Tang, Geshi; Wang, Hang; Qiu, Rujin; Liang, Libo; Yin, Hejun

2017-02-01

This paper presents an interplanetary optical navigation algorithm based on two spherical celestial bodies. The remarkable characteristic of the method is that key navigation parameters can be estimated depending entirely on known sizes and ephemerides of two celestial bodies, especially positioning is realized through a single image and does not rely on traditional terrestrial radio tracking any more. Actual Earth-Moon group photos captured by China's Chang'e-5T1 probe were used to verify the effectiveness of the algorithm. From 430,000 km away from the Earth, the camera pointing accuracy reaches 0.01° (one sigma) and the inertial positioning error is less than 200 km, respectively; meanwhile, the cost of the ground control and human resources are greatly reduced. The algorithm is flexible, easy to implement, and can provide reference to interplanetary autonomous navigation in the solar system.

Category V Compliant Container for Mars Sample Return Missions

NASA Technical Reports Server (NTRS)

Dolgin, Benjamin; Sanok, Joseph; Sevilla, Donald; Bement, Laurence J.

2000-01-01

A novel containerization technique that satisfies Planetary Protection (PP) Category V requirements has been developed and demonstrated on the mock-up of the Mars Sample Return Container. The proposed approach uses explosive welding with a sacrificial layer and cut-through-the-seam techniques. The technology produces a container that is free from Martian contaminants on an atomic level. The containerization technique can be used on any celestial body that may support life. A major advantage of the proposed technology is the possibility of very fast (less than an hour) verification of both containment and cleanliness with typical metallurgical laboratory equipment. No separate biological verification is required. In addition to Category V requirements, the proposed container presents a surface that is clean from any, even nonviable organisms, and any molecular fragments of biological origin that are unique to Mars or any other celestial body other than Earth.

The Universe in Armenian Mythological Perceptions

NASA Astrophysics Data System (ADS)

Vardumyan, Gohar

2016-12-01

Ancient Armenians' perceptions and knowledge about the Universe and cosmic phenomena are reflected in pre-Christian mythology. Thousands of years ago, myths were woven on celestial bodies, and, in the form of legends, they have reached the present day. Heathen Armenians, as other developed nations of the Ancient World, knew the five planets of the Solar System seen with the naked eye: Mercury, Venus, Mars, Jupiter, Saturn, each of them embodied in mythology by a god or a goddess. In pantheons formed during III-I millennia B.C. those planets of the starry sky are represented as worshipped, as well as the Sun, the Moon, the Milky Way, Hayk-Orion, Great Bear, Libra and other constellations. The perceptions of ancient Armenians about the Universe, the tangle of mythology and astronomy in their world view are revealed in the cults of gods and goddesses personifying celestial bodies and luminaries.

Moon Search Algorithms for NASA's Dawn Mission to Asteroid Vesta

NASA Technical Reports Server (NTRS)

Memarsadeghi, Nargess; Mcfadden, Lucy A.; Skillman, David R.; McLean, Brian; Mutchler, Max; Carsenty, Uri; Palmer, Eric E.

2012-01-01

A moon or natural satellite is a celestial body that orbits a planetary body such as a planet, dwarf planet, or an asteroid. Scientists seek understanding the origin and evolution of our solar system by studying moons of these bodies. Additionally, searches for satellites of planetary bodies can be important to protect the safety of a spacecraft as it approaches or orbits a planetary body. If a satellite of a celestial body is found, the mass of that body can also be calculated once its orbit is determined. Ensuring the Dawn spacecraft's safety on its mission to the asteroid Vesta primarily motivated the work of Dawn's Satellite Working Group (SWG) in summer of 2011. Dawn mission scientists and engineers utilized various computational tools and techniques for Vesta's satellite search. The objectives of this paper are to 1) introduce the natural satellite search problem, 2) present the computational challenges, approaches, and tools used when addressing this problem, and 3) describe applications of various image processing and computational algorithms for performing satellite searches to the electronic imaging and computer science community. Furthermore, we hope that this communication would enable Dawn mission scientists to improve their satellite search algorithms and tools and be better prepared for performing the same investigation in 2015, when the spacecraft is scheduled to approach and orbit the dwarf planet Ceres.

An alternative model of free fall

NASA Astrophysics Data System (ADS)

Lattery, Mark

2018-03-01

In Two World Systems (Galileo 1632/1661 Dialogues Concerning Two New Sciences (New York: Prometheus)), Galileo attempted to unify terrestrial and celestial motions using the Aristotelian principle of circularity. The result was a model of free fall that correctly predicts the linear increase of the velocity of an object released from rest near the surface of the Earth. This historical episode provides an opportunity to communicate the nature of science to students.

Long-Term Variations of the EOP and ICRF2

NASA Technical Reports Server (NTRS)

Zharov, Vladimir; Sazhin, Mikhail; Sementsov, Valerian; Sazhina, Olga

2010-01-01

We analyzed the time series of the coordinates of the ICRF radio sources. We show that part of the radio sources, including the defining sources, shows a significant apparent motion. The stability of the celestial reference frame is provided by a no-net-rotation condition applied to the defining sources. In our case this condition leads to a rotation of the frame axes with time. We calculated the effect of this rotation on the Earth orientation parameters (EOP). In order to improve the stability of the celestial reference frame we suggest a new method for the selection of the defining sources. The method consists of two criteria: the first one we call cosmological and the second one kinematical. It is shown that a subset of the ICRF sources selected according to cosmological criteria provides the most stable reference frame for the next decade.

The Green Bank North Celestial Cap Pulsar Survey: New Pulsars and Future Prospects

NASA Astrophysics Data System (ADS)

Lynch, Ryan S.; Swiggum, Joe; Stovall, Kevin; Chawla, Pragya; DeCesar, Megan E.; Fonseca, Emmanuel; Levin, Lina; Cui, Bingyi; Kondratiev, Vlad; Archibald, Anne; Boyles, Jason; Hessels, Jason W. T.; Jenet, Fredrick; Kaplan, David; Karako-Argaman, Chen; Kaspi, Victoria; Martinez, Jose; McLaughlin, Maura; Ransom, Scott M.; Roberts, Mallory; Siemens, Xavier; Spiewak, Renee; Stairs, Ingrid; van Leeuwn, Joeri; Green Bank North Celestial Cap Survey Collaboration

2018-01-01

The Green Bank North Celestial Cap pulsar survey is the most successful low frequency pulsar survey ever. GBNCC uses the Green Bank telescope to cover the full visible sky at 350 MHz. With the survey over 70% complete, we have discovered over 150 pulsars, including 20 MSPs and 11 RRATs. I will report on the current status of the survey and plans for its completion in the coming years. I will also report on several discoveries including: timing solutions for dozens of new pulsars; new high precision MSPs and their suitability for inclusion in pulsar timing arrays; a new relativistic double neutron star system; new pulsar mass measurements; proper motion measurements for several MSPs; a new mode changing pulsar; interesting new MSP binaries; nulling fraction analyses; and possible implications of the lack of any fast radio bursts in the survey so far.

Voyager Saturn encounter attitude and articulation control experience

NASA Technical Reports Server (NTRS)

Carlisle, G.; Hill, M.

1981-01-01

The Voyager attitude and articulation control system is designed for a three-axis stabilized spacecraft; it uses a biasable sun sensor and a Canopus Star Tracker (CST) for celestial control, as well as a dry inertial reference unit, comprised of three dual-axis dry gryos, for inertial control. A series of complex maneuvers was required during the first of two Voyager spacecraft encounters with Saturn (November 13, 1980); these maneuvers involved rotating the spacecraft simultaneously about two or three axes while maintaining accurate pointing of the scan platform. Titan and Saturn earth occulation experiments and a ring scattering experiment are described. Target motion compensation and the effects of celestial sensor interference are also considered. Failure of the CST, which required an extensive reevaluation of the star reference and attitude control mode strategy, is discussed. Results analyzed thus far show that the system performed with high accuracy, gathering data deeper into Saturn's atmosphere than on any previous planetary encounter.

The effect of ocean tides on the earth's rotation as predicted by the results of an ocean tide model

NASA Technical Reports Server (NTRS)

Gross, Richard S.

1993-01-01

The published ocean tidal angular momentum results of Seiler (1991) are used to predict the effects of the most important semidiurnal, diurnal, and long period ocean tides on the earth's rotation. The separate, as well as combined, effects of ocean tidal currents and sea level height changes on the length-of-day, UT1, and polar motion are computed. The predicted polar motion results reported here account for the presence of the free core nutation and are given in terms of the motion of the celestial ephemeris pole so that they can be compared directly to the results of observations. Outside the retrograde diurnal tidal band, the summed effect of the semidiurnal and diurnal ocean tides studied here predict peak-to-peak polar motion amplitudes as large as 2 mas. Within the retrograde diurnal tidal band, the resonant enhancement caused by the free core nutation leads to predicted polar motion amplitudes as large as 9 mas.

Gravity

NASA Astrophysics Data System (ADS)

Poisson, Eric; Will, Clifford M.

2014-05-01

Preface; 1. Foundations of Newtonian gravity; 2. Structure of self-gravitating bodies; 3. Newtonian orbital dynamics; 4. Minkowski spacetime; 5. Curved spacetime; 6. Post-Minkowskian theory: formulation; 7. Post-Minkowskian theory: implementation; 8. Post-Newtonian theory: fundamentals; 9. Post-Newtonian theory: system of isolated bodies; 10. Post-Newtonian celestial mechanics, astrometry and navigation; 11. Gravitational waves; 12. Radiative losses and radiation reaction; 13. Alternative theories of gravity; References; Index.

Relative optical navigation around small bodies via Extreme Learning Machine

NASA Astrophysics Data System (ADS)

Law, Andrew M.

To perform close proximity operations under a low-gravity environment, relative and absolute positions are vital information to the maneuver. Hence navigation is inseparably integrated in space travel. Extreme Learning Machine (ELM) is presented as an optical navigation method around small celestial bodies. Optical Navigation uses visual observation instruments such as a camera to acquire useful data and determine spacecraft position. The required input data for operation is merely a single image strip and a nadir image. ELM is a machine learning Single Layer feed-Forward Network (SLFN), a type of neural network (NN). The algorithm is developed on the predicate that input weights and biases can be randomly assigned and does not require back-propagation. The learned model is the output layer weights which are used to calculate a prediction. Together, Extreme Learning Machine Optical Navigation (ELM OpNav) utilizes optical images and ELM algorithm to train the machine to navigate around a target body. In this thesis the asteroid, Vesta, is the designated celestial body. The trained ELMs estimate the position of the spacecraft during operation with a single data set. The results show the approach is promising and potentially suitable for on-board navigation.

High Resolution Asteroid Profile by Multi Chord Occultation Observations

NASA Astrophysics Data System (ADS)

Degenhardt, Scott

2009-05-01

For millennia man has observed celestial objects occulting other bodies and distant stars. We have used these celestial synchronicities to measure the properties of objects. On January 1, 1801 Italian astronomer Giusappe Piazzi discovered the first asteroid that would soon be named Ceres. To date 190,000 of these objects have been catalogued, but only a fraction of these have accurate measurements of their true size and shape. The International Occultation Timing Association (IOTA) currently facilitates the prediction and reduction of asteroidal occultations. By measuring the shadow cast on the earth by an asteroid during a stellar occultation one can directly measure the physical size, shape, and position in space of this body to accuracies orders of magnitudes better than the best ground based adaptive optics telescope and can provide verification to 3D inverted reflective lightcurve prediction models. Recent novel methods developed by IOTA involving an individual making multiple observations through unattended remote observing stations have made way for numerous chords of occultation measurement through a single body yielding high resolution profiles of asteroid bodies. Methodology of how observing stations are deployed will be demonstrated, results of some of these observations are presented as comparisons to their inverted lightcurve are shown.

YORP: Its origin

NASA Astrophysics Data System (ADS)

Paddack, Stephen; Rubincam, David P.

2015-11-01

It’s all about photons and their behavior. Yarkovsky (1844-1902) did not have the knowledge we have today about photons and radiation pressure. Nevertheless, he published a pamphlet in 1901 that small rotating celestial bodies could absorb sunlight and reradiate it as heat after a delay, resulting in possible orbital changes, setting the stage for radiation effects in celestial mechanics. Yarkovsly’s work remained obscure until Öpik recalled having read Yarkovsky’s pamphlet. Öpik brought Yarkovsky’s idea to the attention of John A. O’Keefe in the late 1960s. O’Keefe, the mentor for two aspiring PhD students, Paddack and Rubincam, told them about Yarkovsky. In 1968 Paddack postulated that the reflection of sunlight off of small, irregularly shaped celestial bodies could have a significant effect on their spin rates. He referred to this as a windmill effect. Paddack and O’Keefe tested the idea of windmill shapes causing spin by dropping crushed stones with irregular shapes into a swimming pool and watching them twirl. Paddack then mimicked the space environment by placing windmill-shaped artificial objects and tektites in a vacuum chamber on an almost frictionless bearing and spinning them up with a strong source of light, conclusively showing the relation of shape to spin. Earlier in 1954 Radzievskii wrote about the effects radiation pressure on variations in the albedo of small celestial bodies as a means of changing their spin rates. The uniform color of Paddack’s test bodies ruled out Radzievskii’s effect as the cause for the observed spin-up. The Yarkovsky effect was minimized because the test object had a coating of vapor-deposited aluminum with a very high albedo and consequently did not heat up. In 2000 Rubincam applied Paddack’s idea to small asteroids and called it the YORP effect (YORP = Yarkovsky-O’Keefe-Radzievskii-Paddack), to give it a catchy name and sell the idea. In 2007 results were published in Science about the observed behavior of asteroid (54509) 2000 PH5 stating that its spin rate changes because of the YORP effect (Lowery et al and Taylor et al). Since 2000 there have been more than 400 papers and talks with “YORP” in the title or the abstract.

Relativistic Celestial Mechanics of the Solar System

NASA Astrophysics Data System (ADS)

Kopeikin, Sergei; Efroimsky, Michael; Kaplan, George

2011-09-01

The general theory of relativity was developed by Einstein a century ago. Since then, it has become the standard theory of gravity, especially important to the fields of fundamental astronomy, astrophysics, cosmology, and experimental gravitational physics. Today, the application of general relativity is also essential for many practical purposes involving astrometry, navigation, geodesy, and time synchronization. Numerous experiments have successfully tested general relativity to a remarkable level of precision. Exploring relativistic gravity in the solar system now involves a variety of high-accuracy techniques, for example, very long baseline radio interferometry, pulsar timing, spacecraft Doppler tracking, planetary radio ranging, lunar laser ranging, the global positioning system (GPS), torsion balances and atomic clocks. Over the last few decades, various groups within the International Astronomical Union have been active in exploring the application of the general theory of relativity to the modeling and interpretation of high-accuracy astronomical observations in the solar system and beyond. A Working Group on Relativity in Celestial Mechanics and Astrometry was formed in 1994 to define and implement a relativistic theory of reference frames and time scales. This task was successfully completed with the adoption of a series of resolutions on astronomical reference systems, time scales, and Earth rotation models by the 24th General Assembly of the IAU, held in Manchester, UK, in 2000. However, these resolutions only form a framework for the practical application of relativity theory, and there have been continuing questions on the details of the proper application of relativity theory to many common astronomical problems. To ensure that these questions are properly addressed, the 26th General Assembly of the IAU, held in Prague in August 2006, established the IAU Commission 52, "Relativity in Fundamental Astronomy". The general scientific goals of the new commission are to: * clarify the geometrical and dynamical concepts of fundamental astronomy within a relativistic framework, * provide adequate mathematical and physical formulations to be used in fundamental astronomy, * deepen the understanding of relativity among astronomers and students of astronomy, and * promote research needed to accomplish these tasks. The present book is intended to make a theoretical contribution to the efforts undertaken by this commission. The first three chapters of the book review the foundations of celestial mechanics as well as those of special and general relativity. Subsequent chapters discuss the theoretical and experimental principles of applied relativity in the solar system. The book is written for graduate students and researchers working in the area of gravitational physics and its applications inmodern astronomy. Chapters 1 to 3 were written by Michael Efroimsky and Sergei Kopeikin, Chapters 4 to 8 by Sergei Kopeikin, and Chapter 9 by George Kaplan. Sergei Kopeikin also edited the overall text. It hardly needs to be said that Newtonian celestial mechanics is a very broad area. In Chapter 1, we have concentrated on derivation of the basic equations, on explanation of the perturbed two-body problem in terms of osculating and nonosculating elements, and on discussion of the gauge freedom in the six-dimensional configuration space of the orbital parameters. The gauge freedom of the configuration space has many similarities to the gauge freedom of solutions of the Einstein field equations in general theory of relativity. It makes an important element of the Newtonian theory of gravity, which is often ignored in the books on classic celestial mechanics. Special relativity is discussed in Chapter 2. While our treatment is in many aspects similar to the other books on special relativity, we have carefully emphasised the explanation of the Lorentz and Poincaré transformations, and the appropriate transformation properties of geometric objects like vectors and tensors, for example, the velocity, acceleration, force, electromagnetic field, and so on. Chapter 3 is devoted to general relativity. It explains the main ideas of the tensor calculus on curved manifolds, the theory of the affine connection and parallel transport, and the mathematical and physical foundations of Einstein's approach to gravity. Within this chapter, we have also included topics which are not well covered in standard books on general relativity: namely, the variational analysis on manifolds and the multipolar expansion of gravitational radiation. Chapter 4 introduces a detailed theory of relativistic reference frames and time scales in an N-body system comprised of massive, extended bodies - like our own solar system. Here, we go beyond general relativity and base our analysis on the scalar-tensor theory of gravity. This allows us to extend the domain of applicability of the IAU resolutions on relativistic reference frames, which in their original form were applicable only in the framework of general relativity. We explain the principles of construction of reference frames, and explore their relationship with the solutions of the gravitational field equations. We also discuss the post-Newtonian multipolemoments of the gravitational field from the viewpoint of global and local coordinates. Chapter 5 discusses the principles of derivation of transformations between reference frames in relativistic celestial mechanics. The standard parameterized post-Newtonian (PPN) formalism by K. Nordtevdt and C. Will operates with a single coordinate frame covering the entire N-body system, but it is insufficient for discussion of more subtle relativistic effects showing up in orbital and rotational motion of extended bodies. Consideration of such effects require, besides the global frame, the introduction of a set of local frames needed to properly treat each body and its internal structure and dynamics. The entire set of global and local frames allows us to to discover and eliminate spurious coordinate effects that have no physical meaning. The basic mathematical technique used in our theoretical treatment is based on matching of asymptotic post-Newtonian expansions of the solutions of the gravity field equations. In Chapter 6, we discuss the principles of relativistic celestial mechanics of massive bodies and particles. We focus on derivation of the post-Newtonian equations of orbital and rotational motion of an extended body possessing multipolar moments. These moments couple with the tidal gravitational fields of other bodies, making the motion of the body under consideration very complicated. Simplification is possible if the body can be assumed spherically symmetric. We discuss the conditions under which this simplification can be afforded, and derive the equations of motion of spherically-symmetric bodies. These equations are solved in the case of the two-body problem, and we demonstrate the rich nature of the possible coordinate presentations of such a solution. The relativistic celestial mechanics of light particles (photons) propagating in a time-dependent gravitational field of an N-body system is addressed in Chapter 7. This is a primary subject of relativistic astrometry which became especially important for the analysis of space observations from the Hipparcos satellite in the early 1990s. New astrometric space missions, orders of magnitude more accurate than Hipparcos, for example, Gaia, SIM, JASMINE, and so on, will require even more complete developments. Additionally, relativistic effects play an important role in other areas of modern astronomy, such as, pulsar timing, very long baseline radio interferometry, cosmological gravitational lensing, and so on. High-precision measurements of gravitational light bending in the solar system are among the most crucial experimental tests of the general theory of relativity. Einstein predicted that the amount of light bending by the Sun is twice that given by a Newtonian theory of gravity. This prediction has been confirmed with a relative precision about 0.01%. Measurements of light bending by major planets of the solar system allow us to test the dynamical characteristics of spacetime and draw conclusions about the ultimate speed of gravity as well as to explore the so-called gravitomagnetic phenomena. Chapter 8 deals with the theoretical principles and methods of the high-precision gravimetry and geodesy, based on the framework of general relativity. A gravitational field and the properties of geocentric and topocentric reference frames are described by the metric tensor obtained from the Einstein equations with the help of post-Newtonian iterations. Bymatching the asymptotic, post-Newtonian expansions of the metric tensor in geocentric and topocentric coordinates, we derive the relationship between the reference frames, and relativistic corrections to the Earth's force of gravity and its gradient. Two definitions of a relativistic geoid are discussed, and we prove that these geoids coincide under the condition of a constant rigid-body rotation of the Earth.We consider, as a model of the Earth's matter, the notion of the relativistic level surface of a self-gravitating perfect fluid. We discover that, under conditions of constant rigid rotation of the fluid and hydrostatic behavior of tides, the post-Newtonian equation of the level surface is the same as that of the relativistic geoid. In the conclusion of this chapter, a relativistic generaisation of the Clairaut's equation is obtained. Chapter 9 is a practical guide to the relativistic resolutions of the IAU, with enough background information to place these resolutions into the context of the late twentieth century positional astronomy. These resolutions involve the definitions of reference systems, time scales, and Earth rotationmodels; and some of the resolutions are quite detailed. Although the recommended Earth rotation models have not been developed ab initio within the relativistic framework presented in the other resolutions (in that regard, there still exist some difficult problems to solve), their relativistic terms are accurate enough for all the current and near-future observational techniques. At that level, the Earth rotation models are consistent with the general relativity framework recommended by the IAU and considered in this book. The chapter presents practical algorithms for implementing the recommended models. The appendices to the book contain a list of astronomical constants and the original text of the relevant IAU resolutions adopted by the IAU General Assemblies in 1997, 2000, 2006, and 2009. Numerous colleagues have contributed to this book in one way or or another. It is a pleasure for us to acknowledge the enlightening discussions which one or more of the authors had on different occasions with Victor A. Brumberg of the Institute of Applied Astronomy (St. Petersburg, Russia); Tianyi Huang and Yi Xie of Nanjing University (China); Edward B. Fomalont of the National Radio Astronomical Observatory (USA); Valeri V. Makarov, William J. Tangren, and James L. Hilton of the US Naval Observatory; Gerhard Schäfer of the Institute of Theoretical Physics (Jena, Germany); Clifford M. Will of Washington University (St. Louis, USA); Ignazio Ciufolini of the Università del Salento and INFN Sezione di Lecce (Italy); and Patrick Wallace, retired from Her Majesty's Nautical Almanac Office (UK). We also would like to thank Richard G. French of Wellesley College (Massachusetts, USA); Michael Soffel and Sergei Klioner of the Technical University of Dresden; Bahram Mashhoon of the University of Missouri-Columbia; John D. Anderson, retired from the Jet Propulsion Laboratory (USA); the late Giacomo Giampieri, also of JPL; Michael Kramer, Axel Jessner, and Norbert Wex of the Max-Planck-Institut für Radioastronomie (Bonn, Germany); Alexander F. Zakharov of the Institute of Theoretical and Experimental Physics (Moscow, Russia); the late Yuri P. Ilyasov from Astro Space Center of Russian Academy of Science; Michael V. Sazhin, Vladimir A. Zharov, and Igor Yu. Vlasov of the Sternberg Astronomical Institute (Moscow, Russia); and Vladimir B. Braginsky of Moscow State University (Russia) for their remarks and comments, all of which helped us to properly formulate the theoretical concepts and other material presented in this book. The discussions among themembers of the IAU Worki! ng Group on Relativity in Celestial Mechanics and Astrometry as well as those within the Working Group on Nomenclature for Fundamental Astronomy have also been quite valuable and have contributed to what is presented here. The numerous scientific papers written by Nicole Capitaine of the Paris Observatory and her collaborators have been essential references. Victor Slabinski and Dennis D. McCarthy of the US Naval Observatory, P. Kenneth Seidelmann of the University of Virginia, Catherine Y. Hohenkerk of Her Majesty's Nautical Almanac Office, and E. Myles Standish, retired from the Jet Propulsion Laboratory, reviewed early drafts of the material that became Chapter 9 and made many substantial suggestions for improvement. We were, of course, influenced by many other textbooks available in this field. We would like to pay particular tribute to: C.W. Misner, K. S. Thorne and J. A. Wheeler "Gravitation" V.A. Brumberg "Essential Relativistic Celestial Mechanics" B.F. Schutz "Geometrical Methods of Mathematical Physics" M.H. Soffel "Relativity in Celestial Mechanics, Astrometry and Geodesy" C.M. Will "Theory and Experiment in Gravitational Physics". There are many other books and influential papers that are important as well which are referenced in the relevant parts of the present book. Not one of our aforementioned colleagues is responsible for any remaining errors or omissions in this book, for which, of course, the authors bear full responsibility. Last, but by nomeans least,Michael Efroimsky and George Kaplan wish to thank John A. Bangert of the US Naval Observatory for the administrative support which he so kindly provided to the project during all of its stages. Sergei Kopeikin is sincerely grateful to the Research Council of the University of Missouri-Columbia for the generous financial support (grants RL-08-027, URC-08-062B, SRF-09-012) that was essential for the successful completion of the book.

Time-Dependent Selection of an Optimal Set of Sources to Define a Stable Celestial Reference Frame

NASA Technical Reports Server (NTRS)

Le Bail, Karine; Gordon, David

2010-01-01

Temporal statistical position stability is required for VLBI sources to define a stable Celestial Reference Frame (CRF) and has been studied in many recent papers. This study analyzes the sources from the latest realization of the International Celestial Reference Frame (ICRF2) with the Allan variance, in addition to taking into account the apparent linear motions of the sources. Focusing on the 295 defining sources shows how they are a good compromise of different criteria, such as statistical stability and sky distribution, as well as having a sufficient number of sources, despite the fact that the most stable sources of the entire ICRF2 are mostly in the Northern Hemisphere. Nevertheless, the selection of a stable set is not unique: studying different solutions (GSF005a and AUG24 from GSFC and OPA from the Paris Observatory) over different time periods (1989.5 to 2009.5 and 1999.5 to 2009.5) leads to selections that can differ in up to 20% of the sources. Observing, recording, and network improvement are some of the causes, showing better stability for the CRF over the last decade than the last twenty years. But this may also be explained by the assumption of stationarity that is not necessarily right for some sources.

Forecasting scenarios of collision catastrophes produced by celestial body falls

NASA Astrophysics Data System (ADS)

Shor, V.; Kochetova, O.; Chernetenko, Y.; Zheleznov, N.; Deryugin, V.; Zaitsev, A.

2014-07-01

The subject under discussion arose in the course of developing a computer program, which gives the possibility for numerical and graphical modeling of the scenarios of catastrophes caused by collisions of cosmic bodies with the Earth. It is expected that this program can be used for computer-assisted training of the personnel of units of the Ministry for Emergency Situations in the case of a situation caused by the fall of a celestial body on the Earth. Also, it is anticipated that the program can be used in real situations when a dangerous body is discovered on an orbit leading to an imminent collision with the Earth. From the scientific point of view, both variants of use require solving of analogous tasks. In what follows, we discuss both variants. 1. The computation of the circumstances for a fall on the Earth (or approach within short distance) of a real body begins with the determination of its orbit from the observations available using the least-squares method. The mean square error of the representation of the observations on the base of the initial values of the coordinates and the velocities is computed, as well as their covariance matrix. Then, the trajectory of the body's motion is followed by numerical integration starting from the osculating epoch to the collision with the Earth or to its flyby. The computer program takes into account the various cases: at the initial moment, the body can move away from or approach the Earth, it can be outside the sphere of action or inside it. At the moment, when the body enters the sphere of action, the coordinates of the center of the dispersion ellipse on the target plane are computed as well as the dimensions of its axes. Using these data, the probability of collision with the Earth is calculated. Then, the point of penetration of the body into the Earth's atmosphere at a given height above the level of the Earth geoid is determined. In case the body is passing by the Earth, the minimum distance of the body from the Earth center is calculated. If the body penetrates into the atmosphere, the dispersion of such parameters as the longitude and the latitude, the geocentric velocity, azimuth and inclination of the trajectory to the horizontal plane are determined at entry. The energy of the body which is delivered to the Earth is also estimated. Then, the calculation of the body's motion in the atmosphere is fulfilled by taking into account its resistance. Possible dispersion of trajectories is considered, too. The computer program gives the possibility to draw a chart of the area, where the body fell or where the airburst took place, to estimate the destruction level within different distances from the epicenter, and to solve a number of other problems, important for providing help in the calamity area. 2. The training of students for actions in emergency conditions can be best solved through computer modeling of the real situation that could happen in the specified area and in the given time as a result of a fall of a cosmic body having prescribed characteristics. The student is proposed to introduce into the computer program at will the geographical coordinates of a place and to fix the time of the fall of the cosmic body, then select for it such characteristics of its trajectory as the geocentric velocity (within possible limits), azimuth, and inclination with respect to the horizon. It is necessary to introduce the size of the body or its energy and also the lead time (the amount of time that remains before the collision). On the basis of these data, the program determines the heliocentric orbit of the body. After that, numerical integration of the equations of motion is carried out in the time-reversed direction on the time interval equal to the lead time. In the end point, the elements of the new heliocentric orbit are calculated. In order to make subsequent calculations identical to those which are fulfilled in the case of a real body, we generate artificial observations of that body, whose orbit was found by reverse integration, on the time interval equal to the lead time. The moments of observations are selected by chance under the condition that they are distributed uniformly, whereas the observation errors are distributed according to normal distribution. Fictitious observations are used to create the conditional equations and then to form the normal system of equations. Their solution gives close to zero corrections to the parameters that were found by the reverse integration. In reality, these corrections are not used: instead, the covariance matrix found is used as a replacement for the covariance matrix of the parameters obtained by reverse integration. Subsequent actions repeat those which are fulfilled in the case of a real body. As a result, the picture of the body's fall with parameters similar to those which were prescribed by the student is reproduced.

Universal planetary tectonics (supertectonics)

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2009-04-01

Universal planetary tectonics (supertectonics) G. Kochemasov IGEM of the Russian Academy of Sciences, Moscow, Russia, kochem.36@mail.ru The wave planetology [1-3 & others] proceeds from the following: "planetary structures are made by orbits and rotations". A uniform reason makes uniform structures. Inertia-gravity waves arising in planetary bodies due to their movements in Keplerian elliptical orbits with periodically changing accelerations warp these bodies in such way that they acquire polyhedron shapes (after interference of standing waves of four directions). Strong Newtonian gravity makes bodies larger than ~400 to 500 km in diameter globular and polyhedra are rarely seen. Only geomorphologic, geologic and geophysical mapping can develop these hidden structures. But small bodies, normally less than ~ 300 to 400 km in diameter, often show parts of the polyhedra, rarely fully developed forms (the asteroid Steins and satellite Amalthea present rather perfect forms of "diamond"). Depending on warping wavelengths (they make harmonics) various Plato's figures superimposed on each other can be distinguished. The fundamental wave 1 produces a tetrahedron, intrinsically dichotomic figure in which a vertex (contraction) always is opposed to a face (expansion). From the recent examples the best is the saturnian northern hexagon (a face) opposed to the southern hurricane (a vertex). The first overtone wave 2 is responsible for creation of structural octahedra. Whole ‘diamonds" and their parts are known [4, 5]. Other overtones produce less developed (because of smaller wave amplitudes) planetary shapes complicating main forms. Thus, the first common structural peculiarity of planetary bodies is their polyhedron nature. Not less important is the second common structural peculiarity. As all globular or smaller more or less isometric bodies rotate, they have an angular momentum. It is inevitably different in tropic and extra-tropic belts having uneven radii or distances to the rotation axe. But this unevenness is undesirable because it creates tectonic stresses and increases energetic status that is against the natural tendency to minimize these physical characteristics. So, a body tends to lower angular momentum of tropics and increase it in extra-tropics. With the same angular velocity it remains only mass and radius to play in this tendency. Tropical belt is destructed (for an example, the lithosphere disintegration in solid bodies), extra-tropical belts add dense material (plumes), expand - the constructive tendency [6]. Both tectonic peculiarities-polyhedrons and constructive - destructive tendencies - are common for celestial bodies of various classes. They are characteristic for our star, planets, satellites and small bodies. That is why a term "supertectonics" seems rather suitable. References: [1] Kochemasov G.G. Concerted wave supergranulation of the solar system bodies // 16th Russian-American microsymposium on planetology, Abstracts, Moscow, Vernadsky Inst. (GEOKHI), 1992, 36-37. [2] Kochemasov G.G. Tectonic dichotomy, sectoring and granulation of Earth and other celestial bodies // Proceedings of the International Symposium on New Concepts in Global Tectonics, "NCGT-98 TSUKUBA", Geological Survey of Japan, Tsukuba, Nov 20-23, 1998, p. 144-147. [3] Kochemasov G.G. Theorems of wave planetary tectonics // Geophys. Res. Abstr., 1999, V.1, №3, 700. [4] Kochemasov G.G. Plato' polyhedra as shapes of small icy satellites // Geophys. Res. Abstracts, Vol. 10, 2008, EGU2008-A-01271, CD-ROM; [5] Kochemasov G.G. (1999) "Diamond" and "dumb-bells"-like shapes of celestial bodies induced by inertia-gravity waves // 30th Vernadsky-Brown microsymposium on comparative planetology, Abstracts, Moscow, Vernadsky Inst.,, 49-50; [6] Kochemasov G.G. Tectonics of rotating celestial globes // Vernadsky-Brown microsymposium 48, 20-22 Oct. 2008, Moscow, Abstr. m48_20.

Synergies in Astrometry: Predicting Navigational Error of Visual Binary Stars

NASA Astrophysics Data System (ADS)

Gessner Stewart, Susan

2015-08-01

Celestial navigation can employ a number of bright stars which are in binary systems. Often these are unresolved, appearing as a single, center-of-light object. A number of these systems are, however, in wide systems which could introduce a margin of error in the navigation solution if not handled properly. To illustrate the importance of good orbital solutions for binary systems - as well as good astrometry in general - the relationship between the center-of-light versus individual catalog position of celestial bodies and the error in terrestrial position derived via celestial navigation is demonstrated. From the list of navigational binary stars, fourteen such binary systems with at least 3.0 arcseconds apparent separation are explored. Maximum navigational error is estimated under the assumption that the bright star in the pair is observed at maximum separation, but the center-of-light is employed in the navigational solution. The relationships between navigational error and separation, orbital periods, and observers' latitude are discussed.

Planetary cores, their energy flux relationship, and its implications

NASA Astrophysics Data System (ADS)

Johnson, Fred M.

2018-02-01

Integrated surface heat flux data from each planet in our solar system plus over 50 stars, including our Sun, was plotted against each object's known mass to generate a continuous exponential curve at an R-squared value of 0.99. The unexpected yet undeniable implication of this study is that all planets and celestial objects have a similar mode of energy production. It is widely accepted that proton-proton reactions require hydrogen gas at temperatures of about 15 million degrees, neither of which can plausibly exist inside a terrestrial planet. Hence, this paper proposes a nuclear fission mechanism for all luminous celestial objects, and uses this mechanism to further suggest a developmental narrative for all celestial bodies, including our Sun. This narrative was deduced from an exponential curve drawn adjacent to the first and passing through the Earth's solid core (as a known prototype). This trend line was used to predict the core masses for each planet as a function of its luminosity.

A new numerical theory of Earth rotation

NASA Astrophysics Data System (ADS)

Gerlach, Enrico; Klioner, Sergei; Soffel, Michael

2012-08-01

Nowadays the rotation of the Earth can be observed with an accuracy of about 0.01 milliarcseconds (mas ), while theoretical models are able to describe this motion at a level of 1 mas. This mismatch is partly due to the enormous complexity of the involved processes, operating on different time scales and driven by a large variety of physical effects. But al so partly due to the used models, which often use simplified and linearized equations to obtain the solution analytically. In this work we present our new numerical theory of the rotation of the Earth. The model underlying the theory is fully compatible with the post - Newtonian approximation of general relativity and is formulated using ordinary differential equations for the angles describing the orientation of the Earth (or its particular layers) in the GCRS. These equations are then solved numerically to describe the rotational motion with highest accuracy. Being initially developed for a rigid Earth our theory was extended towards a more realistic Earth model. In particular, we included 3 different layers (crust, fluid outer core and solid inner core) and all important coupling torques between them as well as all important effects of non - rigidity, such as elastic deformation, relative angular momenta due to atmosphere and ocean etc. In our presentation we will describe the details of our work and compare i t to the currently used models of Earth rotation. Further, we discuss possible applications of our numerical theory to obtain high - accuracy models of rotational motion of other celestial bodies such as Mercury.

A method of initial orbit determination from three or more observations on a short arc. (Russian Title: Метод определения первоначальной орбиты по трем и более наблюдениям на короткой дуге)

NASA Astrophysics Data System (ADS)

Shefer, V. A.

2010-12-01

A new method is suggested for computing the initial orbit of a small celestial body from its three or more pairs of angular measurements at three times. The method is based on using the approach that we previously developed for constructing the intermediate orbit from minimal number of observations. This intermediate orbit allows for most of the perturbations in the motion of the body under study. The method proposed uses the Herget's algorithmic scheme that makes it possible to involve additional observations as well. The methodical error of orbit computation by the proposed method is two orders smaller than the corresponding error of the Herget's approach based on the construction of the unperturbed Keplerian orbit. The new method is especially efficient if applied to high-accuracy observational data covering short orbital arcs.

A new method of preliminary orbit determination from three or more observations on a short arc. (Russian Title: Новый метод определения предварительной орбиты по трем и более наблюдениям на короткой дуге)

NASA Astrophysics Data System (ADS)

Shefer, V. A.

2011-07-01

A new method is suggested for finding the preliminary orbit of a small celestial body from its three or more pairs of angular measurements at three times. The method is based on using the approach that we previously developed for constructing the intermediate orbit from minimal number of observations. This intermediate orbit allows for most of the perturbations in the motion of the body under study. The method proposed uses the Herget's algorithmic scheme that makes it possible to involve additional observations as well. The methodical error of orbit computation by the proposed method is two orders smaller than the corresponding error of the commonly used approach based on the construction of the unperturbed Keplerian orbit. The new method is especially efficient if applied to high-accuracy observational data covering short orbital arcs.

Chaotic Transport in Circumterrestrial Orbits

NASA Astrophysics Data System (ADS)

Rosengren, Aaron Jay

2018-04-01

The slow deformation of circumterrestrial orbits in the medium region, subject to lunisolar secular resonances, is well approximated by a Hamiltonian system with 2.5 degrees of freedom. This dynamical model is referred to in the astrophysical and celestial dynamics communities as the quadrupolar, secular, hierarchical three-body problem, and, in the non-autonomous case, gives rise to the classical Kozai-Lidov mechanism. In the time-dependent model, brought about in our case by the Moon's perturbed motion, the action variables of the system may experience chaotic variations and large drifts due to the possible overlap of nearby resonances. Using variational chaos indicators, we compute high-resolution portraits of the action space, revealing the existence of tori and structures filling chaotic regions. Our refined and elaborate calculations allow us to isolate precise initial conditions near specific areas of interest and to study their asymptotic behavior in time. We highlight in particular how the drift in phase space is mediated by the complement of the numerically detected KAM tori. Despite their reputed normality, Earth satellite orbits can possess an extraordinarily rich spectrum of dynamical behaviors, and, like the small body remnants of Solar system formation, they have all the complications that make them very interesting candidates for testing the modern tools of chaos theory.

Astrometry of Single-Chord Occultations: Application to the 1993 Triton Event

NASA Technical Reports Server (NTRS)

Olkin, Catherine B.; Elliot, J. L.; Bus, Schelte J.; McDonald, Stephen W.; Dahn, Conrad C.

1996-01-01

This paper outlines a method for reducing astrometric data to derive the closest approach time and distance to the center of an occultation shadow for a single observer. The method applies to CCD frames, strip scans or photographic plates and uses a set of field stars of unknown positions to define a common coordinate system for all frames. The motion of the occulting body is used to establish the transformation between this common coordinate system and the celestial coordinate system of the body's ephemeris. This method is demonstrated by application to the Tr6O occultation by Triton on 1993 July 10 UT. Over an interval of four nights that included the occultation time, 80 frames of Triton and Tr6O were taken near the meridian with the U.S. Naval Observatory (USNO) 61-inch astrometric reflector. Application of the method presented here to these data yields a closest approach distance of 359 +/- 133 km (corresponding to 0.017 +/- 0.006 arcsec) for the occultation chord obtained with the Kuiper Airborne Observatory (KAO). Comparison of the astrometric closest approach time with the KAO light-curve midtime shows a difference of 2.2 +/- 4.1 s. Relative photometry of Triton and Tr6O, needed for photometric calibration of the occultation light curve, is also presented.

Integración automatizada de las ecuaciones de Lagrange en el movimiento orbital.

NASA Astrophysics Data System (ADS)

Abad, A.; San Juan, J. F.

The new techniques of algebraic manipulation, especially the Poisson Series Processor, permit the analytical integration of the more and more complex problems of celestial mechanics. The authors are developing a new Poisson Series Processor, PSPC, and they use it to solve the Lagrange equation of the orbital motion. They integrate the Lagrange equation by using the stroboscopic method, and apply it to the main problem of the artificial satellite theory.

An intermediate orbit calculated from three position vectors: accuracy of approximation of a perturbed motion. (Russian Title: Промежуточная орбита, вычисленная по трем векторам положения: точность аппроксимации возмущенного движения)

NASA Astrophysics Data System (ADS)

Shefer, V. A.

2015-12-01

We examine intermediate perturbed orbit proposed by the author previously, defined from the three position vectors of a small celestial body. It is shown theoretically, that at a small reference time interval covering the body positions the approximation accuracy of real motion by this orbit corresponds approximately to the fourth order of tangency. The smaller reference interval of time, the better this correspondence. Laws of variation of the methodical errors in constructing intermediate orbit subject to the length of reference time interval are deduced. According to these laws, the convergence rate of the method to the exact solution (upon reducing the reference interval of time) in the general case is higher by three orders of magnitude than in the case of conventional methods using Keplerian unperturbed orbit. The considered orbit is among the most accurate in set of orbits of their class determined by the order of tangency. The theoretical results are validated by numerical examples. The work was supported by the Ministry of Education and Science of the Russian Federation, project no. 2014/223(1567).

Origin and continuation of 3/2, 5/2, 3/1, 4/1 and 5/1 resonant periodic orbits in the circular and elliptic restricted three-body problem

NASA Astrophysics Data System (ADS)

Antoniadou, Kyriaki I.; Libert, Anne-Sophie

2018-06-01

We consider a planetary system consisting of two primaries, namely a star and a giant planet, and a massless secondary, say a terrestrial planet or an asteroid, which moves under their gravitational attraction. We study the dynamics of this system in the framework of the circular and elliptic restricted three-body problem, when the motion of the giant planet describes circular and elliptic orbits, respectively. Originating from the circular family, families of symmetric periodic orbits in the 3/2, 5/2, 3/1, 4/1 and 5/1 mean-motion resonances are continued in the circular and the elliptic problems. New bifurcation points from the circular to the elliptic problem are found for each of the above resonances, and thus, new families continued from these points are herein presented. Stable segments of periodic orbits were found at high eccentricity values of the already known families considered as whole unstable previously. Moreover, new isolated (not continued from bifurcation points) families are computed in the elliptic restricted problem. The majority of the new families mainly consists of stable periodic orbits at high eccentricities. The families of the 5/1 resonance are investigated for the first time in the restricted three-body problems. We highlight the effect of stable periodic orbits on the formation of stable regions in their vicinity and unveil the boundaries of such domains in phase space by computing maps of dynamical stability. The long-term stable evolution of the terrestrial planets or asteroids is dependent on the existence of regular domains in their dynamical neighbourhood in phase space, which could host them for long-time spans. This study, besides other celestial architectures that can be efficiently modelled by the circular and elliptic restricted problems, is particularly appropriate for the discovery of terrestrial companions among the single-giant planet systems discovered so far.

Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua).

PubMed

Micheli, Marco; Farnocchia, Davide; Meech, Karen J; Buie, Marc W; Hainaut, Olivier R; Prialnik, Dina; Schörghofer, Norbert; Weaver, Harold A; Chodas, Paul W; Kleyna, Jan T; Weryk, Robert; Wainscoat, Richard J; Ebeling, Harald; Keane, Jacqueline V; Chambers, Kenneth C; Koschny, Detlef; Petropoulos, Anastassios E

2018-06-27

'Oumuamua (1I/2017 U1) is the first known object of interstellar origin to have entered the Solar System on an unbound and hyperbolic trajectory with respect to the Sun 1 . Various physical observations collected during its visit to the Solar System showed that it has an unusually elongated shape and a tumbling rotation state 1-4 and that the physical properties of its surface resemble those of cometary nuclei 5,6 , even though it showed no evidence of cometary activity 1,5,7 . The motion of all celestial bodies is governed mostly by gravity, but the trajectories of comets can also be affected by non-gravitational forces due to cometary outgassing 8 . Because non-gravitational accelerations are at least three to four orders of magnitude weaker than gravitational acceleration, the detection of any deviation from a purely gravity-driven trajectory requires high-quality astrometry over a long arc. As a result, non-gravitational effects have been measured on only a limited subset of the small-body population 9 . Here we report the detection, at 30σ significance, of non-gravitational acceleration in the motion of 'Oumuamua. We analyse imaging data from extensive observations by ground-based and orbiting facilities. This analysis rules out systematic biases and shows that all astrometric data can be described once a non-gravitational component representing a heliocentric radial acceleration proportional to r -2 or r -1 (where r is the heliocentric distance) is included in the model. After ruling out solar-radiation pressure, drag- and friction-like forces, interaction with solar wind for a highly magnetized object, and geometric effects originating from 'Oumuamua potentially being composed of several spatially separated bodies or having a pronounced offset between its photocentre and centre of mass, we find comet-like outgassing to be a physically viable explanation, provided that 'Oumuamua has thermal properties similar to comets.

Tides in a body librating about a spin-orbit resonance: generalisation of the Darwin-Kaula theory

NASA Astrophysics Data System (ADS)

Frouard, Julien; Efroimsky, Michael

2017-09-01

The Darwin-Kaula theory of bodily tides is intended for celestial bodies rotating without libration. We demonstrate that this theory, in its customary form, is inapplicable to a librating body. Specifically, in the presence of libration in longitude, the actual spectrum of Fourier tidal modes differs from the conventional spectrum rendered by the Darwin-Kaula theory for a nonlibrating celestial object. This necessitates derivation of formulae for the tidal torque and the tidal heating rate, that are applicable under libration. We derive the tidal spectrum for longitudinal forced libration with one and two main frequencies, generalisation to more main frequencies being straightforward. (By main frequencies we understand those emerging due to the triaxiality of the librating body.) Separately, we consider a case of free libration at one frequency (once again, generalisation to more frequencies being straightforward). We also calculate the tidal torque. This torque provides correction to the triaxiality-caused physical libration. Our theory is not self-consistent: we assume that the tidal torque is much smaller than the permanent-triaxiality-caused torque, so the additional libration due to tides is much weaker than the main libration due to the permanent triaxiality. Finally, we calculate the tidal dissipation rate in a body experiencing forced libration at the main mode, or free libration at one frequency, or superimposed forced and free librations.

Search for Open binaries in the Southern Celestial Hemisphere using SPM4

NASA Astrophysics Data System (ADS)

Dávila, E.; Vieira, K.; Rosales, K.

2018-01-01

Open binaries' weak gravitational binding makes them vulnerable to any perturbation, turning them into excellent probes of the gravitational field where they are located. Currently there are only a few hundreds known or suspected open binaries, therefore a search for more of these systems is highly encouraging by looking for pairs of stars with common proper motions in an extensive, deep, and high quality astrometric catalog such as the SPM4 (Girard et al. 2011).

The ontogenetic development of orientation capabilities

NASA Technical Reports Server (NTRS)

Emlen, S. T.

1972-01-01

The effects of celestial references on the navigation ability of birds are discussed. Tests were conducted in a planetarium with indigo buntings to determine the amount of stellar pattern which could be removed before disorientation occurred. It was determined that young birds have a predisposition to respond to the apparent rotational motion of the night sky. It was concluded that the peak in responsiveness to rotational information is presented during the first summer of life, prior to the first migration season.

The ancient Armenian calendars' connection with the celestial bodies

NASA Astrophysics Data System (ADS)

Broutian, G. H.

2015-07-01

The two oldest Armenian calendars - the Haykian and Protohaykian calendars were connected with observations of celestial bodies. Particularly since 2341 B.C. the heliacal rising of the first star of Orion was used to determine the day of the main holiday - Nawasard. Before that the observations of the same star were used in Protohaykian calendar to determine both the beginning and the end of the year. The year was determined as the duration of visibility of the star Betelgeuse. The year started with the heliacal rising of this star and ended with its heliacal setting. The remaining duration was considered to be out of the year. There are also evidences in Armenian medieval literary sources concerning the observations of heliacal rising and setting of Pleiades. An attempt was made to substantiate that the large symbol carved on the rock platform of the small hill in Metzamor also concerns to the Pleiades and shows the direction of heliacal rising of Pleiades.

“SLIMPLECTIC” INTEGRATORS: VARIATIONAL INTEGRATORS FOR GENERAL NONCONSERVATIVE SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsang, David; Turner, Alec; Galley, Chad R.

2015-08-10

Symplectic integrators are widely used for long-term integration of conservative astrophysical problems due to their ability to preserve the constants of motion; however, they cannot in general be applied in the presence of nonconservative interactions. In this Letter, we develop the “slimplectic” integrator, a new type of numerical integrator that shares many of the benefits of traditional symplectic integrators yet is applicable to general nonconservative systems. We utilize a fixed-time-step variational integrator formalism applied to the principle of stationary nonconservative action developed in Galley et al. As a result, the generalized momenta and energy (Noether current) evolutions are well-tracked. Wemore » discuss several example systems, including damped harmonic oscillators, Poynting–Robertson drag, and gravitational radiation reaction, by utilizing our new publicly available code to demonstrate the slimplectic integrator algorithm. Slimplectic integrators are well-suited for integrations of systems where nonconservative effects play an important role in the long-term dynamical evolution. As such they are particularly appropriate for cosmological or celestial N-body dynamics problems where nonconservative interactions, e.g., gas interactions or dissipative tides, can play an important role.« less

Stars, Galaxies, and the Origin of Chemical Elements

NASA Astrophysics Data System (ADS)

Peter, Ulmschneider

"That I am mortal I know, and that my days are numbered, but when in my mind I follow the multiply entwined orbits of the stars, then my feet do no longer touch the Earth. At the table of Zeus himself do I eat Ambrosia, the food of the Gods". These words by Ptolemy from around 125 A.D. are handed down together with his famous book The Almagest, the bible of astronomy for some 1500 years. They capture mankind's deep fascination with the movements of the heavens, and the miracles of the biological world. After the Babylonians observed the motions of the Sun, Moon, and planets for millennia, the ancient Greeks were the first to speculate about the nature of these celestial bodies. Yet it is only as a consequence of developments in the last 150 years that a much clearer picture of the physical universe has begun to emerge. Among the most important discoveries have been the stellar parallax, confirming Copernicus's heliocentric system, the realization that galaxies are comprised of billions of stars, the awareness of the size of the universe, and the evolutionary nature of living organisms.

Dynamics of Multibody Systems Near Lagrangian Points

NASA Astrophysics Data System (ADS)

Wong, Brian

This thesis examines the dynamics of a physically connected multi-spacecraft system in the vicinity of the Lagrangian points of a Circular Restricted Three-Body System. The spacecraft system is arranged in a wheel-spoke configuration with smaller and less massive satellites connected to a central hub using truss/beams or tether connectors. The kinematics of the system is first defined, and the kinetic, gravitational potential energy and elastic potential energy of the system are derived. The Assumed Modes Method is used to discretize the continuous variables of the system, and a general set of ordinary differential equations describing the dynamics of the connectors and the central hub are obtained using the Lagrangian method. The flexible body dynamics of the tethered and truss connected systems are examined using numerical simulations. The results show that these systems experienced only small elastic deflections when they are naturally librating or rotating at moderate angular velocities, and these deflections have relatively small effect on the attitude dynamics of the systems. Based on these results, it is determined that the connectors can be modeled as rigid when only the attitude dynamics of the system is of interest. The equations of motion of rigid satellites stationed at the Lagrangian points are linearized, and the stability conditions of the satellite are obtained from the linear equations. The required conditions are shown to be similar to those of geocentric satellites. Study of the linear equations also revealed the resonant conditions of rigid Lagrangian point satellites, when a librational natural frequency of the satellite matches the frequency of its station-keeping orbit leading to large attitude motions. For tethered satellites, the linear analysis shows that the tethers are in stable equilibrium when they lie along a line joining the two primary celestial bodies of the Three-Body System. Numerical simulations are used to study the long term dynamics of two sample rigid bodies when they are in different periodic orbits around a collinear point, and the tether librations of a two-tether system in the same orbits. The results show that the rigid satellites and the tethered system experience greater attitude motions when they are in larger periodic orbits. The dynamics of variable length systems are also studied in order to determine the control cost associated with moving the end bodies in a gapless spiral to cover the area spanned by the system. The control cost is relatively low during tether deployment, and negligible effort is required to maintain the angular velocity of the tethered system after deployment. A set of recommendations for the applications of Lagrangian-point physically-connected systems are presented as well as some future research directions are suggested.

The Role of Celestial Compass Information in Cataglyphis Ants during Learning Walks and for Neuroplasticity in the Central Complex and Mushroom Bodies

PubMed Central

Grob, Robin; Fleischmann, Pauline N.; Grübel, Kornelia; Wehner, Rüdiger; Rössler, Wolfgang

2017-01-01

Central place foragers are faced with the challenge to learn the position of their nest entrance in its surroundings, in order to find their way back home every time they go out to search for food. To acquire navigational information at the beginning of their foraging career, Cataglyphis noda performs learning walks during the transition from interior worker to forager. These small loops around the nest entrance are repeatedly interrupted by strikingly accurate back turns during which the ants stop and precisely gaze back to the nest entrance—presumably to learn the landmark panorama of the nest surroundings. However, as at this point the complete navigational toolkit is not yet available, the ants are in need of a reference system for the compass component of the path integrator to align their nest entrance-directed gazes. In order to find this directional reference system, we systematically manipulated the skylight information received by ants during learning walks in their natural habitat, as it has been previously suggested that the celestial compass, as part of the path integrator, might provide such a reference system. High-speed video analyses of distinct learning walk elements revealed that even exclusion from the skylight polarization pattern, UV-light spectrum and the position of the sun did not alter the accuracy of the look back to the nest behavior. We therefore conclude that C. noda uses a different reference system to initially align their gaze directions. However, a comparison of neuroanatomical changes in the central complex and the mushroom bodies before and after learning walks revealed that exposure to UV light together with a naturally changing polarization pattern was essential to induce neuroplasticity in these high-order sensory integration centers of the ant brain. This suggests a crucial role of celestial information, in particular a changing polarization pattern, in initially calibrating the celestial compass system. PMID:29184487

The Role of Celestial Compass Information in Cataglyphis Ants during Learning Walks and for Neuroplasticity in the Central Complex and Mushroom Bodies.

PubMed

Grob, Robin; Fleischmann, Pauline N; Grübel, Kornelia; Wehner, Rüdiger; Rössler, Wolfgang

2017-01-01

Central place foragers are faced with the challenge to learn the position of their nest entrance in its surroundings, in order to find their way back home every time they go out to search for food. To acquire navigational information at the beginning of their foraging career, Cataglyphis noda performs learning walks during the transition from interior worker to forager. These small loops around the nest entrance are repeatedly interrupted by strikingly accurate back turns during which the ants stop and precisely gaze back to the nest entrance-presumably to learn the landmark panorama of the nest surroundings. However, as at this point the complete navigational toolkit is not yet available, the ants are in need of a reference system for the compass component of the path integrator to align their nest entrance-directed gazes. In order to find this directional reference system, we systematically manipulated the skylight information received by ants during learning walks in their natural habitat, as it has been previously suggested that the celestial compass, as part of the path integrator, might provide such a reference system. High-speed video analyses of distinct learning walk elements revealed that even exclusion from the skylight polarization pattern, UV-light spectrum and the position of the sun did not alter the accuracy of the look back to the nest behavior. We therefore conclude that C. noda uses a different reference system to initially align their gaze directions. However, a comparison of neuroanatomical changes in the central complex and the mushroom bodies before and after learning walks revealed that exposure to UV light together with a naturally changing polarization pattern was essential to induce neuroplasticity in these high-order sensory integration centers of the ant brain. This suggests a crucial role of celestial information, in particular a changing polarization pattern, in initially calibrating the celestial compass system.

Somewhere, Beyond the Sea: Advancing Geochemical Sensor Technologies for Biological and Abiotic Analyses on Ocean Worlds

NASA Astrophysics Data System (ADS)

Girguis, P. R.; Hoer, D.; Michel, A.; Wankel, S. D.; Baker, I.; Farr, N.

2018-05-01

Here we present our data from recent efforts aimed at examining the relationships among abiotic and biological processes in our ocean. These technologies may help us address that enduring question as to whether life exists on other celestial bodies.

Feasibility study of scanning celestial Attitude System (SCADS) for Earth Resources Technology Satellite (ERTS)

NASA Technical Reports Server (NTRS)

1971-01-01

The feasibility of using the Scanning Celestial Attitude Determination System (SCADS) during Earth Resources Technology Satellite (ERTS) missions to compute an accurate spacecraft attitude by use of stellar measurements is considered. The spacecraft is local-vertical-stabilized. A heuristic discussion of the SCADS concept is first given. Two concepts are introduced: a passive system which contains no moving parts, and an active system in which the reticle is caused to rotate about the sensor's axis. A quite complete development of the equations of attitude motions is then given. These equations are used to generate the true attitude which in turn is used to compute the transit times of detectable stars and to determine the errors associated with the SCADS attitude. A more complete discussion of the analytical foundation of SCADS concept and its use for the geometries particular to this study, as well as salient design parameters for the passive and active systems are included.

The Bruce Medalists at 100

NASA Astrophysics Data System (ADS)

Tenn, Joseph S.

2007-12-01

In 2007 the Astronomical Society of the Pacific awarded the 100th Catherine Wolfe Bruce gold medal for lifetime contributions to astronomy. The first medalist, Simon Newcomb in 1898, was a celestial mechanician who supervised the computations of orbits and compilation of almanacs, while the second, Arthur Auwers in 1899, observed visually and compiled catalogs of stellar positions and motions. In contrast the last two medalists, Martin Harwit in 2007 and Frank Low in 2006, are pioneers of infrared astronomy from airplanes and satellites. In between have come theoretical and experimental physicists, mathematicians, and radio astronomers, but the majority of medalists have been optical observers, celestial mechanicians (in the early years) and theoretical astrophysicists. Although astronomers are usually honored with the medal twenty to sixty years after their best work is done, we are starting to see more practitioners of the new astronomies, but to date there have been few representatives of the large teams that now dominate astronomical research. I will present an overview of the medalists and how their fields, styles and demographic characteristics have changed.

Risk of Adverse Health and Performance Effects of Celestial Dust Exposure

NASA Technical Reports Server (NTRS)

Scully, Robert R.; Meyers, Valerie E.

2015-01-01

Crew members can be directly exposed to celestial dust in several ways. After crew members perform extravehicular activities (EVAs), they may introduce into the habitat dust that will have collected on spacesuits and boots. Cleaning of the suits between EVAs and changing of the Environmental Control Life Support System filters are other operations that could result in direct exposure to celestial dusts. In addition, if the spacesuits used in exploration missions abrade the skin, as current EVA suits have, then contact with these wounds would provide a source of exposure. Further, if celestial dusts gain access to a suit's interior, as was the case during the Apollo missions, the dust could serve as an additional source of abrasions or enhance suit-induced injuries. When a crew leaves the surface of a celestial body and returns to microgravity, the dust that is introduced into the return vehicle will "float," thus increasing the opportunity for ocular and respiratory injury. Because the features of the respirable fraction of lunar dusts indicate they could be toxic to humans, NASA conducted several studies utilizing lunar dust simulants and authentic lunar dust to determine the unique properties of lunar dust that affect physiology, assess the dermal and ocular irritancy of the dust, and establish a permissible exposure limit for episodic exposure to airborne lunar dust during missions that would involve no more than 6 months stay on the lunar surface. Studies, with authentic lunar soils from both highland (Apollo 16) and mare (Apollo17) regions demonstrated that the lunar soil is highly abrasive to a high fidelity model of human skin. Studies of lunar dust returned during the Apollo 14 mission from an area of the moon in which the soils were comprised of mineral constituents from both major geological regions (highlands and mares regions) demonstrated only minimal ocular irritancy, and pulmonary toxicity that was less than the highly toxic terrestrial crystalline silica (Permissible Exposure Limit [PEL] 0.05 mg/m3) but more toxic than the nuisance dust titanium dioxide (TiO2 [PEL 5.0 mg/m3]). A PEL for episodic exposure to airborne lunar dust during a six-month stay on the lunar surface was established, in consultation with an independent, extramural panel of expert pulmonary toxicologists, at 0.3 mg/m3. The PEL provided for lunar dust is limited to the conditions and exposure specified therefore additional research remains to be accomplished with lunar dust to further address the issues of activation, address other areas of more unique lunar geology (Glotch et al., 2010; Greenhagen et al., 2010), examine potential toxicological effects of inhaled or ingested dust upon other organ systems, such cardiovascular, nervous systems, and examine effects of acute exposure to massive doses of dust such as may occur during off-nominal situations. Work to support the establishment of PELs for Martian dust and dusts of asteroids remains to be accomplished. The literature that describes health effects of exposure to toxic terrestrial dusts provides substantial basis for concern that prolonged exposure to respirable celestial dust could be detrimental to human health. Celestial bodies where a substantial portion of the dust is in the respirable range or where the dusts have large reactive surface areas or contain transition metals or volatile organics, represent greater risks of adverse effects from exposure to the dust. It is possible that in addition to adverse effects to the respiratory system, inhalation and ingestion of celestial dusts could pose risks to other systems

Collocation of equilibria in gravitational field of triangular body via mass redistribution

NASA Astrophysics Data System (ADS)

Burov, Alexander A.; Guerman, Anna D.; Nikonov, Vasily I.

2018-05-01

We consider a gravitating system with triangular mass distribution that can be used as approximation of gravitational field for small irregular celestial bodies. In such system, the locations of equilibrium points, that is, the points where the gravitational forces are balanced, are analyzed. The goal is to find the mass distribution which provides equilibrium in a pre-assigned location near the triangular system, and to study the stability of this equilibrium.

Distant retrograde orbits for the Moon's exploration

NASA Astrophysics Data System (ADS)

Sidorenko, Vladislav

We discuss the properties of the distant retrograde orbits (which are called quasi-satellite orbits also) around Moon. For the first time the distant retrograde orbits were described by J.Jackson in studies on restricted three body problem at the beginning of 20th century [1]. In the synodic (rotating) reference frame distant retrograde orbit looks like an ellipse whose center is slowly drifting in the vicinity of minor primary body while in the inertial reference frame the third body is orbiting the major primary body. Although being away the Hill sphere the third body permanently stays close enough to the minor primary. Due to this reason the distant retrograde orbits are called “quasi-satellite” orbits (QS-orbits) too. Several asteroids in solar system are in a QS-orbit with respect to one of the planet. As an example we can mention the asteroid 2002VE68 which circumnavigates Venus [2]. Attention of specialists in space flight mechanics was attracted to QS-orbits after the publications of NASA technical reports devoted to periodic moon orbits [3,4]. Moving in QS-orbit the SC remains permanently (or at least for long enough time) in the vicinity of small celestial body even in the case when the Hill sphere lies beneath the surface of the body. The properties of the QS-orbit can be studied using the averaging of the motion equations [5,6,7]. From the theoretical point of view it is a specific case of 1:1 mean motion resonance. The integrals of the averaged equations become the parameters defining the secular evolution of the QS-orbit. If the trajectory is robust enough to small perturbations in the simplified problem (i.e., restricted three body problem) it may correspond to long-term stability of the real-world orbit. Our investigations demonstrate that under the proper choice of the initial conditions the QS-orbits don’t escape from Moon or don’t impact Moon for long enough time. These orbits can be recommended as a convenient technique for the large scale browsing of the Moon’s environment. [1] Jackson, J. (1913) MNRAS, 74, 62-82. [2] Mikkola, S., Brasser, R., Wiegert, P., Innanen, K. (2004) MNRAS, 351, L63-L65. [3] Broucke, R.A. (1968) NASA Technical Report 32-1168, JPL. [4] Broucke, R.A. (1969) NASA Technical Report 32-1360, JPL. [5] Kogan, A.I. (1989) Cosmic Research, 26, 705-710. [6] Namouni, F. (1999) Icarus, 6, 293-314. [7] Sidorenko, V.V., Neishtadt, A.I., Artemyev, A.V., Zelenyi, L.M. (2013) Doklady Physics, 58, 207-211.

A semi-analytical method of computation of oceanic tidal perturbations in the motion of artificial satellites

NASA Technical Reports Server (NTRS)

Musen, P.

1973-01-01

The method of expansion of the satellite's perturbations, as caused by the oceanic tides, into Fourier series is discussed. The coefficients of the expansion are purely numerical and peculiar to each particular satellite. Such a method is termed as semi-analytical in celestial mechanics. Gaussian form of the differential equations for variation of elements, with the right hand sides averaged over the orbit of the satellite, is convenient to use with the semi-analytical expansion.

SOFA & astrometry

NASA Astrophysics Data System (ADS)

Hohenkerk, C.

2015-08-01

The International Astronomical Union's (IAU) Standards of Fundamental Astronomy (SOFA) software library has in the last year introduced a tranche of 32 new routines dealing with the subject area "astrometry". This poster provides a guide to enable users to get to grips easily with the various routines for the transformations between ICRS, ICRS astrometric, GCRS, Celestial Intermediate and observed positions of stars, together with their underlying routines for proper motion, parallax, aberration, light deflection and refraction. A summary of the current status of SOFA is also included.

Gufa, a Unique Cultural Ritual-a Tale of a Forbidden Sun and a Girl

NASA Astrophysics Data System (ADS)

Shrestha, Pritisha

2016-10-01

Gufa, one of the traditional rituals, has been performed in Nepal since time immemorial by indigenous Newar people. In Gufa, a young girl who just had her first period is hidden in a sunless room for twelve consecutive days. This paper expounds the importance of ritual and its nexus with astronomy especially while interpreting how the daily motions of celestial objects have influenced the establishment and devolvement of a deep-rooted custom of Gufa.

75 FR 81587 - Coding of Design Marks in Registrations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-28

..., attention Cynthia C. Lynch; by hand-delivery to the Trademark Assistance Center, Concourse Level, James.... SUPPLEMENTARY INFORMATION: Background Pursuant to 35 U.S.C. 41(i)(1)-(2), the USPTO maintains a publicly... SHAPES-ASTRO, which encompasses all astronomical shapes consisting of celestial bodies (such as the moon...

Space Science in Action: Astronomy [Videotape].

ERIC Educational Resources Information Center

1999

This videotape recording teaches students about constellations, star movement, and how scientists have studied celestial bodies throughout history from Ptolemy to Copernicus to the work of the Hubble Space Telescope. An interview with Kathy Thornton, one of the astronauts who repaired the Hubble while in orbit, is featured. A hands-on activity…

The Triangles of Aristarchus

ERIC Educational Resources Information Center

Hirshfeld, Alan W.

2004-01-01

Greek philosopher mathematician, Aristarchus of Samos, in the third century B.C., proposed that the sun held in the central position, casting its light symmetrically outward on the other celestial bodies. He demonstrated the way in which a person could use simple observations and elementary geometry to measure on a cosmic scale.

Remote Access Astronomy

ERIC Educational Resources Information Center

Beare, Richard; Bowdley, David; Newsam, Andrew; Roche, Paul

2003-01-01

There is still nothing to beat the excitement and fulfilment that you can get from observing celestial bodies on a clear dark night, in a remote location away from the seemingly ever increasing light pollution from cities. However, it is also the specific requirements for good observing that can sometimes prevent teachers from offering this…

Structure and evolutionary history of the solar system

NASA Technical Reports Server (NTRS)

Alfven, H.; Arrhenius, G.

1975-01-01

General principles and observational facts concerning the solar system are examined, taking into account the orbits of planets and satellites, the small bodies, the resonance structure, spin and tides, and postaccretional changes in the solar system. A description is given of the accretion of celestial bodies and the plasma phase is considered. Aspects of chemical differentiation and the matrix of the groups of bodies are also discussed, giving attention to chemical compositions in the solar system, meteorites and their precursor states, mass distribution and the critical velocity, and the structure of the groups.

Does Vesta Have Moons?: Dawn's Search for Satellites

NASA Technical Reports Server (NTRS)

McFadden, L. A.; Sykes, M. V.; Tricarico, P.; Carsenty, U.; Gutierrez-Marques, P.; Jacobson, R. A.; Joy, S.; Keller, H. U.; Li, J.-Y.; McLean, B.;

Advanced relativistic VLBI model for geodesy

NASA Astrophysics Data System (ADS)

Soffel, Michael; Kopeikin, Sergei; Han, Wen-Biao

2017-07-01

Our present relativistic part of the geodetic VLBI model for Earthbound antennas is a consensus model which is considered as a standard for processing high-precision VLBI observations. It was created as a compromise between a variety of relativistic VLBI models proposed by different authors as documented in the IERS Conventions 2010. The accuracy of the consensus model is in the picosecond range for the group delay but this is not sufficient for current geodetic purposes. This paper provides a fully documented derivation of a new relativistic model having an accuracy substantially higher than one picosecond and based upon a well accepted formalism of relativistic celestial mechanics, astrometry and geodesy. Our new model fully confirms the consensus model at the picosecond level and in several respects goes to a great extent beyond it. More specifically, terms related to the acceleration of the geocenter are considered and kept in the model, the gravitational time-delay due to a massive body (planet, Sun, etc.) with arbitrary mass and spin-multipole moments is derived taking into account the motion of the body, and a new formalism for the time-delay problem of radio sources located at finite distance from VLBI stations is presented. Thus, the paper presents a substantially elaborated theoretical justification of the consensus model and its significant extension that allows researchers to make concrete estimates of the magnitude of residual terms of this model for any conceivable configuration of the source of light, massive bodies, and VLBI stations. The largest terms in the relativistic time delay which can affect the current VLBI observations are from the quadrupole and the angular momentum of the gravitating bodies that are known from the literature. These terms should be included in the new geodetic VLBI model for improving its consistency.

Aerospace Environment. Aerospace Education I.

ERIC Educational Resources Information Center

Savler, D. S.; Smith, J. C.

This book is one in the series on Aerospace Education I. It briefly reviews current knowledge of the universe, the earth and its life-supporting atmosphere, and the arrangement of celestial bodies in outer space and their physical characteristics. Chapter 1 includes a brief survey of the aerospace environment. Chapters 2 and 3 examine the…

Periodic solutions of a spring-pendulum system.

NASA Technical Reports Server (NTRS)

Broucke, R.; Baxa, P. A.

1973-01-01

A study has been made of a dynamical system composed of a pendulum and a harmonic oscillator, in order to show the remarkable resemblance with many classical celestial mechanics problems, in particular, the restricted three-body problem. It is shown that the well-known investigations of periodic orbits can be applied to the present dynamics problem.

Frombork Castle and Nicolas Copernicus

NASA Astrophysics Data System (ADS)

Kogure, Tomokazu

2004-10-01

Nicolas Copernicus spent his last half life at Frombork Castle in Poland, where he wrote "On the Revolution of the Celestial Bodies." The author visited Frombork and had a strong impression by his great personality in late Renaissance, not only in astronomy, but also in activities in a wide field of economical, political affaires, renovation of currency.

Lithuanian Astronomy

NASA Astrophysics Data System (ADS)

Sudzius, J.; Murdin, P.

2002-01-01

Lithuanian folklore, archaic calendars and terminology show that Lithuanians were interested in astronomy from ancient times. A lot of celestial bodies have names of Lithuanian origin that are not related to widely accepted ancient Greek mythology. For example, the Milky Way is named `Pauksciu Takas' (literally the way of birds), the constellation of the Great Bear `Didieji Grizulo Ratai' (literal...

Book Review: Stars (Copyright 1985, Golden Press; New York)

NASA Astrophysics Data System (ADS)

Marigza, R. N., Jr.

2009-06-01

Stars is a part of the Golden Guides collection produced by Golden Press. It is a small 160 page paperback guide to the constellations, the sun, the moon, planets, and other celestial bodies. The book is convenient to carry along wherever you go, making it an easy to access reference material.

Aerothermal Instrumentation Loads To Implement Aeroassist Technology in Future Robotic and Human Missions to MARS and Other Locations Within the Solar System

NASA Technical Reports Server (NTRS)

Parmar, Devendra S.; Shams, Qamar A.

2002-01-01

The strategy of NASA to explore space objects in the vicinity of Earth and other planets of the solar system includes robotic and human missions. This strategy requires a road map for technology development that will support the robotic exploration and provide safety for the humans traveling to other celestial bodies. Aeroassist is one of the key elements of technology planning for the success of future robot and human exploration missions to other celestial bodies. Measurement of aerothermodynamic parameters such as temperature, pressure, and acceleration is of prime importance for aeroassist technology implementation and for the safety and affordability of the mission. Instrumentation and methods to measure such parameters have been reviewed in this report in view of past practices, current commercial availability of instrumentation technology, and the prospects of improvement and upgrade according to the requirements. Analysis of the usability of each identified instruments in terms of cost for efficient weight-volume ratio, power requirement, accuracy, sample rates, and other appropriate metrics such as harsh environment survivability has been reported.

Recombination of radiation defects in solid methane: neutron sources and cryo-volcanism on celestial bodies

NASA Astrophysics Data System (ADS)

Kirichek, O.; Savchenko, E. V.; Lawson, C. R.; Khyzhniy, I. V.; Jenkins, D. M.; Uyutnov, S. A.; Bludov, M. A.; Haynes, D. J.

2018-03-01

Physicochemical properties of solid methane exposed to ionizing radiation have attracted significant interest in recent years. Here we present new trends in the study of radiation effects in solid methane. We particularly focus on relaxation phenomena in solid methane pre-irradiated by energetic neutrons and electron beam. We compare experimental results obtained in the temperature range from 10K to 100K with a model based on the assumption that radiolysis defect recombinations happen in two stages, at two different temperatures. In the case of slow heating up of the solid methane sample, irradiated at 10K, the first wave of recombination occurs around 20K with a further second wave taking place between 50 and 60K. We also discuss the role of the recombination mechanisms in “burp” phenomenon discovered by J. Carpenter in the late 1980s. An understanding of these mechanisms is vital for the designing and operation of solid methane moderators used in advanced neutron sources and could also be a possible explanation for the driving forces behind cryo-volcanism on celestial bodies.

The gravitational potential of axially symmetric bodies from a regularized green kernel

NASA Astrophysics Data System (ADS)

Trova, A.; Huré, J.-M.; Hersant, F.

2011-12-01

The determination of the gravitational potential inside celestial bodies (rotating stars, discs, planets, asteroids) is a common challenge in numerical Astrophysics. Under axial symmetry, the potential is classically found from a two-dimensional integral over the body's meridional cross-section. Because it involves an improper integral, high accuracy is generally difficult to reach. We have discovered that, for homogeneous bodies, the singular Green kernel can be converted into a regular kernel by direct analytical integration. This new kernel, easily managed with standard techniques, opens interesting horizons, not only for numerical calculus but also to generate approximations, in particular for geometrically thin discs and rings.

IRIS-S - Extending geodetic very long baseline interferometry observations to the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Carter, W. E.; Robertson, D. S.; Nothnagel, A.; Nicolson, G. D.; Schuh, H.

1988-12-01

High-accuracy geodetic very long baseline interferometry measurements between the African, Eurasian, and North American plates have been analyzed to determine the terrestrial coordinates of the Hartebeesthoek observatory to better than 10 cm, to determine the celestial coordinates of eight Southern Hemisphere radio sources with milliarc second (mas) accuracy, and to derive quasi-independent polar motion, UTI, and nutation time series. Comparison of the earth orientation time series with ongoing International Radio Interferometric Surveying project values shows agreement at about the 1 mas of arc level in polar motion and nutation and 0.1 ms of time in UTI. Given the independence of the observing sessions and the unlikeliness of common systematic error sources, this level of agreement serves to bound the total errors in both measurement series.

The Discovery of the Regular Movements of Celestial Bodies and the Development of Monotheism in the Ancient Near East

NASA Astrophysics Data System (ADS)

Lanfranchi, G. B.

2011-06-01

For Ancient Mesopotamians, astronomical phenomena were signs signifying the gods' judgment on human behaviour. Mesopotamian scholars studied celestial phenomena for understanding the gods' will, and strongly developed astrology. From the 8th to the 6th century BC Assyrian and Babylonian astronomers achieved the ability to predict solar and lunar eclipses, and the planets' movements through mathematical calculations. Predictability of astral phenomena solicited the awareness that they are all regular, and that the universe is governed by an eternal, immutable order fixed at its very beginning. This finally favoured the idea that the cosmic order depended on the will of one god only, displacing polytheism in favour of monotheism; and astrology lost its religious importance as a mean to know the divine will.

The historical tension between astronomical theory and observation

NASA Astrophysics Data System (ADS)

Gingerich, O.

A review of instances in the history of astronomy wherein conflicts between the results of theory and observation occurred, to be later ameliorated or exaggerated by further evidence, is presented. Among the examples are Aristotle's arguments that the form of a celestial body will always be spherical to evenly distribute the mass, and the currently held concept that all celestial objects greater than a few kilometers in radius will be spherical due to gravitational forces. Ptolemy's observations of planetary orbits, however, are noted to have accurately resulted in a numerical model which did not factually represent planetary orbits. It is noted that observation is usually performed with a theory in mind, and interpretation is therefore hindered from clear analysis of phenomena which do not conform to previously held mental models.

The registered distance of the celestial sphere: some historical cross-cultural data.

PubMed

Plug, C

1989-02-01

Estimates of the diameters of the sun and moon expressed in centimetres have been reported by several authors in the past. These estimates imply that the sizes of the sun and moon are perceived as if these bodies are only some tens of metres distant. In this study five units of length that were used by ancient astronomers to estimate arcs on the celestial sphere were investigated. The purpose was to determine whether the lengths and angles represented by these units imply a specific registered distance of the star sphere. The sizes of the Babylonian cubit, Arab fitr and shibr, Greek eclipse digit, and Chinese chang support the conclusion that the registered distance of the stars was about 10 to 40 metres in these four cultures over the last two millennia.

Astronomy, Community, and Modern Calendar Buildings

NASA Astrophysics Data System (ADS)

Campion, N.

2016-01-01

This paper will look at Avon Tyrrell House, a “calendar house” dating from 1891 and an example of nineteenth-century astronomical architecture in England. The paper will suggest that “calendar buildings” may represent a genre of modern astronomical architecture which has, so far, not been studied, were designed to create stronger communities precisely because of their astronomical connections, and indicates scope for further investigation. The paper will contextualize the modern “calendar building” within the tradition of constructing cities and sacred sites as reflections or embodiments of the sky. By creating spaces which were connected to the celestial bodies, it was possible to create human communities which were linked to celestial ones, encouraging social stability and harmony. Such ideas underpinned traditions of the foundation of cities from China, through India, the Middle East, and Mesoamerica.

Protection of the Lifeless Environment in the Solar System

NASA Astrophysics Data System (ADS)

Almar, I.

The main concern of planetary protection policy is how to protect the (hypothetical) extraterrestrial life against contamination and back-contamination. There is almost no interest in the preservation of the existing lifeless surfaces of extraterrestrial bodies, although some planetary transformation plans (in order to exploit hypothetical resources) were made public a long time ago. It should be remembered that planetary environments are practically unchanged since ages and damage caused by any human intervention would be irreversible. Our intention is not to prevent any commercial utilization of Solar System resources, but to make space exploration and exploitation of resources a controlled and well planned endeavor. The three main issues connected with the protection of the lifeless space environment are the following: 1/ The scientific aspect: a limited, well defined initiative to select by scientific investigation areas and objects of highest scientific priority on different celestial bodies. 2/ The legal aspect: to start the drafting of a declaration of principles supporting the protection of selected areas and objects on celestial bodies with a solid surface. It might evolve into an international legal instrument or treaty in order to limit the "free-for-all" intervention and use of Solar System resources. 3/ The societal aspect: to initiate a large scale discussion on the possible "ethical values" of the lifeless environment.

Piazzi On Ceres and Pacific On Earth Are Tectonically Comparable Features

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Earth is more than 10 times larger than Ceres but the wave planetary tectonics [1] is not perplexed with this. Theorem 1 states that "Celestial bodies are dichotomic". This theorem is valid for bodies of various sizes, compositions and physical states. What is common for all of them that they are moving, moving in non-circular orbits, and rotate. These properties are sufficient for invoking inertia forces making celestial bodies oscillate and acquire a convexo-concave shape. of the recent planetological achievements three should be mentioned particularly as they concern small celestial bodies where general rules of body shaping are expressed very sharply. A small aster- oid 433 Eros, the largest asteroid 1 Ceres and Borrelli comet were studied in different scales but all of them have essential features predicted by the wave planetology. The convexo-concave shape of asteroid Eros (stony, 33 km long) is repeated in comet Bor- relli (icy, 8 km long). Borrelli's convex hemisphere is sharply jagged because of exten- sion. The same is observed on Eros ("saddle") but in a lesser degree. Borrelli's concave strongly contracted hemisphere is a source of a large complexly built tail of expulsion. This extruded material samples interior of the comet and leaves whitish spots in the centre of the concave side. Eros also have many signes of past degassing in a form of regular net of pits (craters); in the centre of the concave side is a large complexly built crater Psych. Both oblong bodies -Eros and Borrelli - have different opposite ends: blunt and sharp, predicted by the wave planetology (the Arctic-Antarctic symp- tom). The oblong body of Ceres (major/minor axes of 898/788 km [2] and 970/ 930 km,[Parker &Stern]) according to HST (J.Parker &Stern) has a prominent dusky dark spot (Piazzi) from one side. It occupies a significant part of the asteroid (about 250 km, more than a quarter the size of Ceres) and probably might be assigned to a depression. Tectonically one may compare this depression with the Pacific basin hollow on Earth. One may state that the wave planetology is a science which can predict. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v.1, #3, 700; [2] McCarthy D.W.,Jr., Freeman J.D., Drummond J.D. (1994) High resolution images of Vesta at 1.65 micron // Icarus,v.108, #2, pt.1, 285-297.

Determination of the lunar orbital and rotational parameters and of the ecliptic reference system orientation from LLR measurements and IERS data

NASA Astrophysics Data System (ADS)

Chapront, J.; Chapront-Touzé, M.; Francou, G.

1999-03-01

An analysis of Lunar Laser Ranging (LLR) observations from January 1972 till March 1998 is performed using the lunar theory ELP 2000-96 and the completed Moons' theory of the lunar libration. The LLR station coordinates, polar motion and Universal Time are provided by the International Earth Rotation Service (IERS). In Solution 1 the precession-nutation transformation is given by recent analytical theories, while in Solution 2 it is derived from the IERS daily corrections. Orbital and free libration parameters of the Moon, and coordinates of the reflectors are obtained in both cases. The position of the inertial mean ecliptic of J2000.0 with respect to the equator of the mean Celestial Ephemeris Pole (CEP) of J2000.0 (in Solution 1) and to the International Celestial Reference System (ICRS), the IERS celestial reference system, (in Solution 2) are fit. The position of the mean CEP equator of J2000.0 and of several dynamical reference planes and origins, with respect to ICRS, are derived from these fits (Fig. 1). The leading results are the following: 0farcs057 60+/- 0farcs000 20 (in the equator) for the separation of the origin of right ascensions in ICRS from the ascending node of the inertial mean ecliptic of J2000.0 on the reference plane of ICRS, -0farcs0460 +/- 0farcs0008 (in the ecliptic) for the separation of the latter point from the inertial dynamical mean equinox of J2000.0, -0farcs015 19+/- 0farcs000 35 (in the equator) for the separation of the inertial dynamical mean equinox of J2000.0 from the J2000.0 right ascension origin derived from IERS polar motion and Universal Time and from precise theories of precession-nutation, and 23degr26 arcmin21 farcs405 22+/- 0farcs000 07 for the inertial obliquity of J2000.0. A correction of -0farcs3437 +/- 0farcs0040 /cy to the IAU 1976 value of the precession constant is also obtained (the errors quoted are formal errors).

MGA trajectory planning with an ACO-inspired algorithm

NASA Astrophysics Data System (ADS)

Ceriotti, Matteo; Vasile, Massimiliano

2010-11-01

Given a set of celestial bodies, the problem of finding an optimal sequence of swing-bys, deep space manoeuvres (DSM) and transfer arcs connecting the elements of the set is combinatorial in nature. The number of possible paths grows exponentially with the number of celestial bodies. Therefore, the design of an optimal multiple gravity assist (MGA) trajectory is a NP-hard mixed combinatorial-continuous problem. Its automated solution would greatly improve the design of future space missions, allowing the assessment of a large number of alternative mission options in a short time. This work proposes to formulate the complete automated design of a multiple gravity assist trajectory as an autonomous planning and scheduling problem. The resulting scheduled plan will provide the optimal planetary sequence and a good estimation of the set of associated optimal trajectories. The trajectory model consists of a sequence of celestial bodies connected by two-dimensional transfer arcs containing one DSM. For each transfer arc, the position of the planet and the spacecraft, at the time of arrival, are matched by varying the pericentre of the preceding swing-by, or the magnitude of the launch excess velocity, for the first arc. For each departure date, this model generates a full tree of possible transfers from the departure to the destination planet. Each leaf of the tree represents a planetary encounter and a possible way to reach that planet. An algorithm inspired by ant colony optimization (ACO) is devised to explore the space of possible plans. The ants explore the tree from departure to destination adding one node at the time: every time an ant is at a node, a probability function is used to select a feasible direction. This approach to automatic trajectory planning is applied to the design of optimal transfers to Saturn and among the Galilean moons of Jupiter. Solutions are compared to those found through more traditional genetic-algorithm techniques.

To Mercury dynamics

NASA Astrophysics Data System (ADS)

Barkin, Yu. V.; Ferrandiz, J. M.

Present significance of the study of rotation of Mercury considered as a core-mantle system arises from planned Mercury missions. New high accurate data on Mercury's structure and its physical fields are expected from BepiColombo mission (Anselmi et al., 2001). Investigation of resonant rotation of Mercury, begun by Colombo G. (1966), will play here main part. New approaches to the study of Mercury dynamics and the construction of analytical theory of its resonant rotation are suggested. Within these approaches Mercury is considered as a system of two non-spherical interacting bodies: a core and a mantle. The mantle of Mercury is considered as non-spherical, rigid (or elastic) layer. Inner shell is a liquid core, which occupies a large ellipsoidal cavity of Mercury. This Mercury system moves in the gravitational field of the Sun in resonant traslatory-rotary regime of the resonance 3:2. We take into account only the second harmonic of the force function of the Sun and Mercury. For the study of Mercury rotation we have been used specially designed canonical equations of motion in Andoyer and Poincare variables (Barkin, Ferrandiz, 2001), more convenient for the application of mentioned methods. Approximate observational and some theoretical evaluations of the two main coefficients of Mercury gravitational field J_2 and C22 are known. From observational data of Mariner-10 mission were obtained some first evaluations of these coefficients: J_2 =(8± 6)\\cdot 10-5(Esposito et al., 1977); J_2 =(6± 2)\\cdot 10-5and C22 =(1.0± 0.5)\\cdot 10-5(Anderson et al., 1987). Some theoretical evaluation of ratio of these coefficients has been obtained on the base of study of periodic motions of the system of two non-spherical gravitating bodies (Barkin, 1976). Corresponding values of coefficients consist: J_2 =8\\cdot 10-5and C22 =0.33\\cdot 10-5. We have no data about non-sphericity of inner core of Mercury. Planned missions to Mercury (BepiColombo and Messenger) promise to obtain new and accurate data about dynamics and structure of this planet (Anselmi et al., 2001). There are also some evaluations of moments of inertia Mercury and its core: C/(mR^2)=0.35, C_m /C=0.5± 0.07, (Peal, 1996). Here C and C_m are the moments of inertia of the full Mercury and of its core, m and R is a mass and a mean radius of Mercury. Based on two methods, we consider the rotation of Mercury in the gravitational field of the Sun. First method of perturbation has been effectively applied to the construction of a rotational theory of the Earth for its models as two or three layer celestial body moving in gravitational fields of the Moon, Sun and planets in wide set of papers ranging in 1999-2001 years of Ferrandiz J.M. and Getino J.(2001). Some generalization of this Hamiltonian formalism on the case of cavity (core) with arbitrary dynamical and geometrical oblateness has been obtained in a paper (Barkin, Ferrandiz, 2001). Another method is an analytical method of construction of the resonant rotational motion of synchronous satellites and Mercury, considered as non-spherical rigid bodies. This method has been applied earlier to construction of an analytical theory of rotation of the Moon considered as rigid non-spherical body (Barkin, 1989). Here we modified these methods to apply them to the study of the resonant rotation of a two-layer Mercury. By this we use very effective for the application of perturbation methods and dynamical geometrical illustration of canonical equations in Andoyer and Poincare variables. Main resonant properties of Mercury motion were been described first as generalized Cassini's laws (Colombo, 1966). But Colombo and some anothers scientists (Peal, 1969; Beletskii, 1972; Ward, 1975 and oth.) considered Mercury as rigid non-spherical body sometimes taking into account tidal deformation. Here we have been obtained and formulated these laws and their generalization for a two-layer model of Mercury. On the next step we have evaluated frequencies of free oscillations of core-mantle system of Mercury. Based on the mentioned data about Mercury (Barkin, 1976) we have been obtained the following model values of moments of inertia of the Mercury and for its core:A=0.3499534, B=0.3499667, C=0.35; A_c =B_c =0.1749767, C_c =0.175000 (1quad unit=mR^2, m and R is a mass and a mean radius of the Mercury). Here we used model values for moments of inertia of the core using also some analogy with axysimmetrical model of the core of the Moon from paper Williams et al. (2003). Corresponding periods of free oscillations were determined on the base specially constructed equations of developed theory. They are equal: T_1 =260543\\cdot Trot years and T_2 =0.999468\\cdot Trot (Trot =58.6462 days is a period of Mercury rotation). Last period determines long period of relative oscillation of the core and mantleT_r . The mentioned periods are equal: T_1 =713years and T_r =302years. Barkin's work was accepted by grant SAB2000-0235 of Ministry of Education of Spain and partially by grants AYA2001-0787 and ESP2001-4533 is also aknowledged. References Anderson J.D., Colombo G., Esposito P.B., Lau E.L., Trager G.B.: 1987. The mass, gravity field and ephemeris of Mercury. Icarus, pp. 337-349. Anselmi A., Scoon G.E.N.: 2001. BepiColombo, ESA's Mercury Cornerstone mission. Planetary and Space Science, 49, pp. 1409-1420. Barkin Yu.V.: 1976. About plane periodic motions of a rigid body in gravitational field of a sphere. Astron. J., v. 53, pp. 1110-1119. In Russian. Barkin Yu.V.: 1987. An analytical theory of the lunar rotational motion. Proc. Int. Symp. ``Figure and Dynamics of Earth, Moon and Planets'' (September 1986, Prague). Monograph series of VUGTK. Prague. Pp. 657-677. Beletskij V.V.: 1972. Resonance rotation of celestial bodies and Cassini's laws. Celestial Mechanics, v.6, N3, pp. 356-378. Colombo G.: 1966. Cassini's second and third laws, Astron. J., 71, p. 891. Esposito P.B., Anderson J.D., Ng A.T.Y.: 1977. Experimental determination of Mercury's mass and oblateness. Space Res., v. 17, pp. 639-644. Getino J., Ferrandiz J.M.: 2001. Forced nutations of a two-layer earth model. Monthly Notices of the Royal Astronomical Society, v. 322, Iss. 4, pp. 785-799. Ferrandiz J.M., Barkin Yu.V.: 2001. Dynamics of the rotational motion of the planet with the elastic mantle, liquid core and with the changeable external shell. Proc. of Intern. Conf. ``AstroKazan-2001''. Astronomy and geodesy in new millennium (24-29 September 2001), Kazan State University: Publisher ``DAS'', 2001, p. 123-129. Peal S.J.: 1969. Generalized Cassini's laws, Astron. J., 74, p. 483. Peal S.J.: 1996. Characterizing the core of Mercury. LPS XXVII, 1168. Ward W.R.: 1975. Tidal friction and generalized Cassini's laws in the solar system. Astron. Journal, Vol. 80, N 1, pp. 64-70.

Longitude origins on moving equator II: effects of nutation

NASA Astrophysics Data System (ADS)

Fukushima, T.

We obtained an explicit solution of s, the angle specifying the non-rotating orign (NRO) (Guinot 1979), for the pole uniformly rotating on a circle around an arbitrary fixed direction. Thanks to the obtained formula, we derived an approximate expression of its correction, Δs, due to the fast nutational motion of the pole by ignoring the slow precessional motion. By adopting the IAU 1980 nutation series (Seidelmann 1980) and combining the result with the previous solution for the precessional motion of the Earth's pole (Fukushima 2000), we developed a more precise expression of the global motion of the Celestial Ephemeris Origin (CEO). The current speed of global rotation of CEO amounts to -4.149 688 1"/yr where the contribution of the nutation is small as -38.4μas/yr but non-negligible. The negative sign shows that CEO rotates clockwise with respect to the inertial frame when viewed from the north pole. The long periodic motion of CEO is of the amplitude of the obliquity of ecliptic, around 23.5 degree, and of the period of precession, around 25800 yr. While the effect of nutation on the periodic motion of CEO looks like a series of mixed secular terms, which is simply proportional to the nutation in longitude and is of the order of some tens mas/yr.

An historic discovery around the corner from school: Ceres, a solar system object with an uncertain identity.

NASA Astrophysics Data System (ADS)

Stira, Salvatore

2016-04-01

Ceres is the largest object in the asteroid belt between Mars and Jupiter, and it was discovered on January 1, 1801, by the Italian astronomer Giuseppe Piazzi. The study of Ceres is especially relevant to my students because this celestial body was discovered in Palermo, in the astronomic observatory located in the UNESCO world heritage site "Palazzo dei Normanni", around 500 meters away from the institute where I teach, and because Ceres was considered the patron goddess of Sicily. Moreover, it received scientists and media attention recently because it was explored by the NASA Dawn spacecraft in 2015. The categorization of Ceres has changed more than once and has been the subject of some disagreement. It was originally considered a planet, but was reclassified as an asteroid in the 1850s when many other objects in similar orbits were discovered. Its status changed again in 2006 when it was promoted to dwarf planet, a classification it shares with Pluto and other Kuiper belt objects. The study of this celestial body has a notable educational value, since the uncertain identity of Ceres constitutes an occasion to reflect on the criterions of classification of the natural objects. The history of its discovery allows the students to understand as the scientific method doesn't always consist in the verification of hypothesis through experiments but it sometimes asks for the forecast of facts through mathematical calculations, repeated and methodic observations, the collaboration between scientists of different sectors and nationality. Furthermore, it is a particularly suitable topic for interdisciplinary connections, as regards both scientific and humanistic matters. In order to promote the scientific competences of my first class students, I have developed a learning unit on Ceres, thanks to good cooperation with the Palermo Observatory scientists, particularly active in the astronomic dissemination towards the schools and the citizens. The most meaningful activities of the learning units have been: 1) Working in groups: classification of solar system objects through the use of cards with figures and description of the celestial bodies. 2) A guided tour to Palermo Astronomic Observatory Museum, where stored instruments used by Piazzi for observation of Ceres and the original scientific documentation regarding this important discovery. 3) Internet search of information on the mission Dawn and implementation of Learning objects on this matter. 4) A guided visit to the exhibition "Cerere, da Piazzi a Dawn"; This learning unit, that has aroused interest and active participation among the students, cannot be regarded as closed, because it can be used for the discussion of other matters (for instance the search of the life on other celestial bodies).

A Mathematical Description of the PULSAR Doppler Satellite Tracking Data Editor.

DTIC Science & Technology

1982-09-01

D .2.2 Position Derivatives of the Atmospheric Drag Acceleration:9r (con’t) v ( X r (i 1,2,3) (29) j=1’ k=1 re c. is the Levi - Civita density defined...obliquity of the ecliptic. The ecliptic intersects the celestial equator at two points called the vernal equinox and the autumnal equinox, i.e. the...direction to the earth’s rotation and has a period of approximately 26,000 years. , This conical motion is usually treated as the sum of two components

Computerized method to compensate for breathing body motion in dynamic chest radiographs

NASA Astrophysics Data System (ADS)

Matsuda, H.; Tanaka, R.; Sanada, S.

2017-03-01

Dynamic chest radiography combined with computer analysis allows quantitative analyses on pulmonary function and rib motion. The accuracy of kinematic analysis is directly linked to diagnostic accuracy, and thus body motion compensation is a major concern. Our purpose in this study was to develop a computerized method to reduce a breathing body motion in dynamic chest radiographs. Dynamic chest radiographs of 56 patients were obtained using a dynamic flat-panel detector. The images were divided into a 1 cm-square and the squares on body counter were used to detect the body motion. Velocity vector was measured using cross-correlation method on the body counter and the body motion was then determined on the basis of the summation of motion vector. The body motion was then compensated by shifting the images based on the measured vector. By using our method, the body motion was accurately detected by the order of a few pixels in clinical cases, mean 82.5% in right and left directions. In addition, our method detected slight body motion which was not able to be identified by human observations. We confirmed our method effectively worked in kinetic analysis of rib motion. The present method would be useful for the reduction of a breathing body motion in dynamic chest radiography.

Vienna VLBI and Satellite Software (VieVS) for Geodesy and Astrometry

NASA Astrophysics Data System (ADS)

Böhm, Johannes; Böhm, Sigrid; Boisits, Janina; Girdiuk, Anastasiia; Gruber, Jakob; Hellerschmied, Andreas; Krásná, Hana; Landskron, Daniel; Madzak, Matthias; Mayer, David; McCallum, Jamie; McCallum, Lucia; Schartner, Matthias; Teke, Kamil

2018-04-01

The Vienna VLBI and Satellite Software (VieVS) is state-of-the-art Very Long Baseline Interferometry (VLBI) analysis software for geodesy and astrometry. VieVS has been developed at Technische Universität Wien (TU Wien) since 2008, where it is used for research purposes and for teaching space geodetic techniques. In the past decade, it has been successfully applied on Very Long Baseline Interferometry (VLBI) observations for the determination of celestial and terrestrial reference frames as well as for the estimation of celestial pole offsets, universal Time (UT1-UTC), and polar motion based on least-squares adjustment. Furthermore, VieVS is equipped with tools for scheduling and simulating VLBI observations to extragalactic radio sources as well as to satellites and spacecraft, features which proved to be very useful for a variety of applications. VieVS is now available as version 3.0 and we do provide the software to all interested persons and institutions. A wiki with more information about VieVS is available at http://vievswiki.geo.tuwien.ac.at/.

Multimodal integration in rostral fastigial nucleus provides an estimate of body movement

PubMed Central

Brooks, Jessica X.; Cullen, Kathleen E.

2012-01-01

The ability to accurately control posture and perceive self motion and spatial orientation requires knowledge of both the motion of the head and body. However, while the vestibular sensors and nuclei directly encode head motion, no sensors directly encode body motion. Instead, the convergence of vestibular and neck proprioceptive inputs during self-motion is generally believed to underlie the ability to compute body motion. Here, we provide evidence that the brain explicitly computes an internal estimate of body motion at the level of single cerebellar neurons. Neuronal responses were recorded from the rostral fastigial nucleus, the most medial of the deep cerebellar nuclei, during whole-body, body-under-head, and head-on-body rotations. We found that approximately half of the neurons encoded the motion of the body-in-space, while the other half encoded the motion of the head-in-space in a manner similar to neurons in the vestibular nuclei. Notably, neurons encoding body motion responded to both vestibular and proprioceptive stimulation (accordingly termed bimodal neurons). In contrast, neurons encoding head motion were only sensitive to vestibular inputs (accordingly termed unimodal neurons). Comparison of the proprioceptive and vestibular responses of bimodal neurons further revealed similar tuning in response to changes in head-on-body position. We propose that the similarity in nonlinear processing of vestibular and proprioceptive signals underlies the accurate computation of body motion. Furthermore, the same neurons that encode body motion (i.e., bimodal neurons) most likely encode vestibular signals in a body referenced coordinate frame, since the integration of proprioceptive and vestibular information is required for both computations. PMID:19710303

Tethered spacecraft in asteroid gravitational environment

NASA Astrophysics Data System (ADS)

Burov, Alexander A.; Guerman, Anna D.; Kosenko, Ivan I.; Nikonov, Vasily I.

2018-02-01

Relative equilibria of a pendulum attached to the surface of a uniformly rotating celestial body are considered. The locations of the tether anchor that correspond to a given spacecraft position are defined. The domains, where the spacecraft can be held with the help of such a pendulum, are also described. Stability of the found relative equilibria is studied.

Mobile Cubesat Command and Control (Mc3) 3-Meter Dish Calibration and Capabilities

DTIC Science & Technology

2014-06-01

accuracy of this simple calibration is tested by tracking the sun, an easily accessible celestial body. To track the sun, a Systems Tool Kit ( STK ... visually verified. The shadow created by the dish system when it is pointed directly at the sun is symmetrical. If the dish system is not pointed

Pegasus

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

(the Winged Horse; abbrev. Peg, gen. Pegasi; area 1121 sq. deg.) A northern constellation that extends from Cygnus, Lacerta and Andromeda almost to the celestial equator, and culminates at midnight in early September. It is named after the winged horse in Greek mythology that sprang from the body of Medusa, the Gorgon, when she was beheaded by Perseus, and later was tamed by the hero Bellerophon. ...

Measuring Astronomical Distances with Linear Programming

ERIC Educational Resources Information Center

Narain, Akshar

2015-01-01

A few years ago it was suggested that the distance to celestial bodies could be computed by tracking their position over about 24 hours and then solving a regression problem. One only needed to use inexpensive telescopes, cameras, and astrometry tools, and the experiment could be done from one's backyard. However, it is not obvious to an amateur…

The Young Astrophysicist: A Very Inexpensive Activity to Discuss Spectroscopy

ERIC Educational Resources Information Center

Brockington, Guilherme; Testoni, Leonardo André; Pietrocola, Maurício

2015-01-01

The continuing fascination of young people with celestial bodies leads them to pose challenging questions to their science teachers, such as how was the universe born? How were the stars formed? In this paper we present an extremely inexpensive but highly engaging activity to teach the basics of spectroscopy. Guided by the question "how do…

Dispelling superstitions in Nepalese society with astronomy

NASA Astrophysics Data System (ADS)

Shah, Rishi

2011-06-01

Throughout human history, astronomy has played crucial rôle in the development of our civilization, culture and daily chores of lives that have been influenced by observations of Sun, moon, planets, stars and other cosmic entities. Our ancestors who were hunting and gathering and foraging food while living in caves learned to think logically by gazing at the twinkling stars in the heavens. Seasons for crops plantation were determined, time concept was introduced, entire sky was charted and the motions of celestial objects were meaningfully understood. With the advent of telescopes, the geocentric model of universe was replaced by the revolutionary heliocentric concept of our Solar System. Astronomy dispelled superstitious beliefs strongly prevailing in societies. Closely associated with numerous disciplines of science astronomy is still flourishing worldwide and is attempting to fly us away to those habitable cosmic bodies of our universe. By establishing well-equipped observational infrastructure local and international astronomy research and development could be enhanced. Introduction of astronomy in education system right from school would attract and encourage students to pursue higher studies for enabling them for participating in future international scientific and exploration programmes. Astronomy has helped our society to progress peacefully and efficiently.

Landsat-7 Simulation and Testing Environments

NASA Technical Reports Server (NTRS)

Holmes, E.; Ha, K.; Hawkins, K.; Lombardo, J.; Ram, M.; Sabelhaus, P.; Scott, S.; Phillips, R.

1999-01-01

A spacecraft Attitude Control and Determination Subsystem (ACDS) is heavily dependent upon simulation throughout its entire development, implementation and ground test cycle. Engineering simulation tools are typically developed to design and analyze control systems to validate the design and software simulation tools are required to qualify the flight software. However, the need for simulation does not end here. Operating the ACDS of a spacecraft on the ground requires the simulation of spacecraft dynamics, disturbance modeling and celestial body motion. Sensor data must also be simulated and substituted for actual sensor data on the ground so that the spacecraft will respond by sending commands to the actuators as they will on orbit. And finally, the simulators is the primary training tool and test-bed for the Flight Operations Team. In this paper various ACDS simulation, developed for or used by the Landsat 7 project will be described. The paper will include a description of each tool, its unique attributes, and its role in the overall development and testing of the ACDS. Finally, a section is included which discusses how the coordinated use of these simulation tools can maximize the probability of uncovering software, hardware and operations errors during the ground test process.

Dawes Review 5: Australian Aboriginal Astronomy and Navigation

NASA Astrophysics Data System (ADS)

Norris, Ray P.

2016-08-01

The traditional cultures of Aboriginal Australians include a significant astronomical component, perpetuated through oral tradition, ceremony, and art. This astronomical knowledge includes a deep understanding of the motion of objects in the sky, which was used for practical purposes such as constructing calendars and for navigation. There is also evidence that traditional Aboriginal Australians made careful records and measurements of cyclical phenomena, recorded unexpected phenomena such as eclipses and meteorite impacts, and could determine the cardinal points to an accuracy of a few degrees. Putative explanations of celestial phenomena appear throughout the oral record, suggesting traditional Aboriginal Australians sought to understand the natural world around them, in the same way as modern scientists, but within their own cultural context. There is also a growing body of evidence for sophisticated navigational skills, including the use of astronomically based songlines. Songlines are effectively oral maps of the landscape, and are an efficient way of transmitting oral navigational skills in cultures that do not have a written language. The study of Aboriginal astronomy has had an impact extending beyond mere academic curiosity, facilitating cross-cultural understanding, demonstrating the intimate links between science and culture, and helping students to engage with science.

Formation flying for electric sails in displaced orbits. Part II: Distributed coordinated control

NASA Astrophysics Data System (ADS)

Wang, Wei; Mengali, Giovanni; Quarta, Alessandro A.; Yuan, Jianping

2017-09-01

We analyze a cooperative control framework for electric sail formation flying around a heliocentric displaced orbit, aiming at observing the polar region of a celestial body. The chief spacecraft is assumed to move along an elliptic displaced orbit, while each deputy spacecraft adjusts its thrust vector (that is, both its sail attitude and characteristic acceleration) in order to track a prescribed relative trajectory. The relative motion of the electric sail formation system is formulated in the chief rotating frame, where the control inputs of each deputy are the relative sail attitude angles and the relative lightness number with respect to those of the chief. The information exchange among the spacecraft, characterized by the communication topology, is represented by a weighted graph. Two typical cases, according to whether the communication graph is directed or undirected, are discussed. For each case, a distributed coordinated control law is designed in such a way that each deputy not only tracks the chief state, but also makes full use of information from its neighbors, thus increasing the redundancy and robustness of the formation system in case of failure among the communication links. Illustrative examples show the effectiveness of the proposed approach.

Global tectonic of Enceladus driven by subsidence of South Polar Terrain

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2016-07-01

Enceladus is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of ~200 kg is ejected into space from the South Polar Terrain (SPT) - [1]. Our hypothesis states that this mass loss is the main driving mechanism of the tectonic processes. The hypothesis is presented in [2] and [3]. We find that the loss of the volatiles results in a void, an instability, and motion of solid matter to fill the void. The motion includes: (i) Subsidence of the 'lithosphere' of SPT. (ii) Flow of the matter in the mantle. (iii) Motion of plates adjacent to SPT towards the active region. The numerical model of the subsidence process is developed. It is based on the model of thermal convection in the mantle. Special boundary conditions are applied that could simulate subsidence of SPT. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is ~0.05 mm per yr. However, numerical calculations indicate that all three types of motion are usually important. The role of a given motion depends on the viscosity distribution. Generally, for most of the models the subsidence is ~0.02 mm per yr, but mantle flow and plates' motion also play a role in filling the void. The preliminary results of the numerical model indicate also that the velocity of adjacent plates could be ~0.02 mm per yr for the Newtonian rheology. The SPT is not compressed, so "tiger stripes" could exist for long time. Only after significant subsidence the regime of stresses changes to compression. It means the end of activity in a given region. The future region of activity is suggested. Acknowledgments This work was partially supported by the National Science Centre (grant 2011/01/B/ST10/06653). Computer resources of Interdisciplinary Centre for Mathematical and Computational Modeling of University of Warsaw were also used in the research References [1] Spencer, J. R., et al. (2009) Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer Science, p. 683. [2] Czechowski L. (2015) Mass loss as a driving mechanism of tectonics of Enceladus 46th Lunar and Planetary Science Conference 2030.pdf. [3] Czechowski, L., (2014) Some remarks on the early evolution of Enceladus. Planet. Sp. Sc. 104, 185-199.

On enigmatic properties of the main belt asteroids

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Two properties of the main belt asteroids still bother planetologists: why they are mainly of an oblong shape and why the larger bodies rotate faster than the smaller ones. According to the excepted impact theory constantly produced fragments should be rather more or less of equal dimensions. Larger bodies are more difficult to make rotating by hits than the smaller ones. The comparative wave planetology states that "orbits make structures". It means that as all celestial bodies move in non-round keplerian elliptic (and parabolic) orbits with periodically changing accelerations they are subjected to an action of inertia-gravity waves causing body warpings. These warpings in rotating bodies (but all celestial bodies rotate!) acquire stationary character and 4 ortho- and diagonal directions. An interference of these waves produces uprising (+), subsiding (-) and neutral (0) tectonic blocks size of which depends on the warping wavelengths. The fundamental wave 1 long 2πR makes one hemisphere to rise (bulge) and the opposite one to fall (press in) - this two-segment construction is the ubiquitous tectonic dichotomy. The first overtone wave 2 long πR is responsible for tectonic sectoring complicating the dichotomic segments. This already rather complicated structural picture is further complicated by a warping action of individual waves lengths of which are inversely proportional to orbital frequencies : higher frequency - smaller wave and , vice versa, lower frequency - larger waves. These waves produce tectonic granulation, granule size being a half of a wavelength. All terrestrial planets and the belt asteroids according to their orb. fr. are strictly arranged in the following row of granule sizes: Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. The waves lengths and amplitudes increase with the solar distance, their warping action accordingly increases. If Mercury, Venus and Earth are more or less globular, Mars is already elliptical because two warping waves cannot be inscribed in a sphere otherwise than to stretch a body in one direction and to press it in the perpendicular one. Thus, an enigmatic shape of Mars is explained by this way. Asteroids are subjected to a warping action of the wave that bulges one hemisphere and presses the opposite one making convexo-concave bean shape [1]. This wave resonate (1 to 1) with the fundamental wave causing dichotomy of all celestial bodies . This very strong resonance enhances a warping action. That is why asteroids are flat, oblong and bean-shaped. The bulging hemisphere is always cracked, and this cracking sometimes is so strong that "saddles" appear sometimes cutting body into two or more pieces (binaries, satellites). Eros and the small Trojan satellite of Saturn Calypso (PIA07633) are very similar in this typical shape (convexo-concave shape and a "saddle") though they have different compositions, sizes and strengths. It was 1 shown earlier that degassing and rotations of terrestrial planets may be tied by redistribution of their angular momentum between a solid body and its gaseous envelope [2]. Bodies with higher orb. fr. and thus more finely granulated (Mercury, Venus) are more thoroughly wiped out of its volatiles and rotate slower because a significant part of their momenta gone with atmosphere (The Mercury's atmosphere was destroyed by the solar wind). The main asteroid belt rather stretched (2.2-3.2 a.u.) is composed of metallic, stone and carbonaceous bodies (judging by spectra and meteorites) , the first two dominating its inner part, the third -the outer one (similarity with the inner planets in respect of volatiles distribution). Less degassed asteroids keeping their original mass and "original" momentum (i.e.,the larger bodies) differ from the smaller ones having lost their original mass by degassing and spalling and shared their momenta with gone off parts. That is why the larger bodies are fast, the smaller ones slow rotating. References: [1] Kochemasov G.G. (1999) On convexo-concave shape of small celestial bodies // Asteroids, Comets, Meteors. Cornell Univ., July 26-30, 1999, Abstr. # 24.22; [2] Kochemasov G.G. (2003) Structures of the wave planetology and their projection onto the solar photosphere: why solar supergranules are 30000 km across. // Vernadsky-Brown microsymp. 38, Vernadsky Inst.,Moscow, Russia, Oct. 27-29, 2003, Abstr. (CD-ROM). 2

Work on a New Solar-System Ephemeris: Status Report

NASA Astrophysics Data System (ADS)

Mai, Enrico; Müller, Jürgen

2014-05-01

Currently, within a coordinated project in Germany, integrated methods and procedures for a consistent definition and realization of reference systems on Earth and in space are being developed. Barycentric ephemerides represent a dynamical realization of the Barycentric Celestial Reference System (BCRS), which is fundamental not only for the problem of interplanetary navigation but through its intimate relation to the Geocentric Celestial Reference System (GCRS). In accordance with existing renowned ephemerides (INPOP, DE, EPM) we want to lay the foundation for a new solar-system ephemeris. We collected available observational data for the planets as well as high-precise tracking data to various spacecrafts (interplanetary probes, planetary orbiters and landers). Furthermore, we set up the usual relativistic (post-Newtonian) force model in line with the latest French INPOP ephemeris, with a few exceptions. The focus in modeling is on the lunar librations and asteroid perturbations. Regarding the treatment of the Moon, we draw upon the elaborated modeling within the existing LLR analysis software at IfE and its ongoing improvements. Nowadays, any modern ephemeris, besides perturbations due to general mass inhomogeneities (at least for the Earth and the Moon) and solar flattening, respective figure-figure interactions and tidal effects, proper rotations and librations etc., has to account for the significant gravitational effect of the vast number of minor bodies in the solar-system (especially within the major asteroid belt between Mars and Jupiter) on the long-term evolution of planetary orbits. Due to limited computational resources, one is able to integrate the equations of motion (EOM) of only a comparatively small selection of asteroids simultaneously with the EOM of the major solar-system bodies (i.e., planets, Sun, Moon). On the other hand, one can efficiently account for the remaining asteroids by the introduction of at least one mass ring, the parameters of which (radius, total mass) have to be carefully modeled. Regarding the latter issue we will test the usability of an evolution strategy instead of a simple Monte Carlo method. In future, asteroid modeling will strongly benefit from observational data of the recently started GAIA mission. Here we present a few statistics on the collected observational data, the fundamental force model of the EOM in detail, and first computational results in comparison with the INPOP ephemeris.

INSTRUMENTS AND METHODS OF INVESTIGATION: Spectral and spectral-frequency methods of investigating atmosphereless bodies of the Solar system

NASA Astrophysics Data System (ADS)

Busarev, Vladimir V.; Prokof'eva-Mikhailovskaya, Valentina V.; Bochkov, Valerii V.

2007-06-01

A method of reflectance spectrophotometry of atmosphereless bodies of the Solar system, its specificity, and the means of eliminating basic spectral noise are considered. As a development, joining the method of reflectance spectrophotometry with the frequency analysis of observational data series is proposed. The combined spectral-frequency method allows identification of formations with distinctive spectral features, and estimations of their sizes and distribution on the surface of atmospherelss celestial bodies. As applied to investigations of asteroids 21 Lutetia and 4 Vesta, the spectral frequency method has given us the possibility of obtaining fundamentally new information about minor planets.

Contribution of zonal harmonics to gravitational moment

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.

1991-01-01

It is presently demonstrated that a recursive vector-dyadic expression for the contribution of a zonal harmonic of degree n to the gravitational moment about a small body's center-of-mass is obtainable with a procedure that involves twice differentiating a celestial body's gravitational potential with respect to a vector. The recursive property proceeds from taking advantage of a recursion relation for Legendre polynomials which appear in the gravitational potential. The contribution of the zonal harmonic of degree 2 is consistent with the gravitational moment exerted by an oblate spheroid.

Contribution of zonal harmonics to gravitational moment

NASA Astrophysics Data System (ADS)

Roithmayr, Carlos M.

1991-02-01

It is presently demonstrated that a recursive vector-dyadic expression for the contribution of a zonal harmonic of degree n to the gravitational moment about a small body's center-of-mass is obtainable with a procedure that involves twice differentiating a celestial body's gravitational potential with respect to a vector. The recursive property proceeds from taking advantage of a recursion relation for Legendre polynomials which appear in the gravitational potential. The contribution of the zonal harmonic of degree 2 is consistent with the gravitational moment exerted by an oblate spheroid.

Children's Concepts of the Shape and Size of the Earth, Sun and Moon

ERIC Educational Resources Information Center

Bryce, T. G. K.; Blown, E. J.

2013-01-01

Children's understandings of the shape and relative sizes of the Earth, Sun and Moon have been extensively researched and in a variety of ways. Much is known about the confusions which arise as young people try to grasp ideas about the world and our neighbouring celestial bodies. Despite this, there remain uncertainties about the conceptual models…

Abilities of Celestial Observations in Astronomical Observatory of Physics Institute in Opole

NASA Astrophysics Data System (ADS)

Godłowski, W.; Szpanko, M.

2010-12-01

We present possibilities of astronomical investigation in Astronomical Observatory in Opole. Our observatory uses two telescopes: Celestron CGE-1400 XLT (35 cm) and Meade LX200 (30 cm) with spectrograph and CCD Camera. Main topic of our observational investigation is connected with observations of variable stars, minor bodies of the solar system, blazers and the Sun.

Schwarzschild, Karl (1873-1916)

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Mathematical physicist, born in Frankfurt am Main, Germany, at first worked on celestial mechanics, including POINCARÉ's theory of rotating bodies, the tidal deformation of moons and LAPLACE's origin of the solar system. He became professor at Göttingen and Potsdam. He wrote on relativity and quantum theory. He early on proposed that space was non-Euclidean, giving a lower limit for the radius of...

MaMBA - a functional Moon and Mars Base Analog

NASA Astrophysics Data System (ADS)

Heinicke, C.; Foing, B.

2017-09-01

Despite impressive progress in robotic exploration of celestial bodies, robots are believed to never reach the effectiveness and efficiency of a trained human. Consequently, ESA proposes to build an international Moon Village in roughly 15 years and NASA plans for the first manned mission to Mars shortly after. One of the challenges still remaining is the need for a shelter, a habitat which allows human spacefarers to safely live and work on the surface of a celestial body. Although a number of prototype habitats has been built during the last decades and inhabited for various durations (e.g. MDRS, FMARS, HI-SEAS, M.A.R.S.), these habitats are typically equipped for studies on human factors and would not function in an extraterrestrial environment. Project MaMBA (Moon and Mars Base Analog) aims to build the first functional habitat based on the lessons learned from intermediate and long duration missions at the mentioned habitats. The habitat will serve for testing technologies like life support, power systems, and interplanetary communi­cation. Special attention will be given to the develop­ment of the geoscience laboratory module. Crews will live and work inside the habitat to ensure its functionality.

Astronomical aspects of cosmic threats: new problems and approaches to asteroid—comet hazard following the chelyabinsk event of February 15, 2013

NASA Astrophysics Data System (ADS)

Shustov, B. M.; Shugarov, A. S.; Naroenkov, S. A.; Prokhorov, M. E.

2015-10-01

A new definition of hazardous celestial bodies (HCBs) is introduced, in which the lower limit of the size of a HCB is reduced to 10 m. A new definition for threatening and collisional orbits of DCBs is introduced. The main astronomical factors that must be taken into account when creating systems for the detection of HCBs are analyzed. The most important of these are the uniformity of the distribution of points (regions) for the appearance of HCBs on the celestial sphere in near-Earth space and the practical limit for the velocity of approach of a HCB of 20 km/s (for 90% of bodies). It is shown that the creation of a system for the nearby detection of asteroids and comets arriving from the daytime sky requires the use of a space-based system. A concept for such a system, in which one or several optical telescopes are placed in the vicinity of the libration point L1 for the Sun—Earth system, is developed. Preliminary plans for such a system, called the System for the Detection of Daytime Asteroids (SDDA), are briefly described.

Quaternion regularization in celestial mechanics, astrodynamics, and trajectory motion control. III

NASA Astrophysics Data System (ADS)

Chelnokov, Yu. N.

2015-09-01

The present paper1 analyzes the basic problems arising in the solution of problems of the optimum control of spacecraft (SC) trajectory motion (including the Lyapunov instability of solutions of conjugate equations) using the principle of the maximum. The use of quaternion models of astrodynamics is shown to allow: (1) the elimination of singular points in the differential phase and conjugate equations and in their partial analytical solutions; (2) construction of the first integrals of the new quaternion; (3) a considerable decrease of the dimensions of systems of differential equations of boundary value optimization problems with their simultaneous simplification by using the new quaternion variables related with quaternion constants of motion by rotation transformations; (4) construction of general solutions of differential equations for phase and conjugate variables on the sections of SC passive motion in the simplest and most convenient form, which is important for the solution of optimum pulse SC transfers; (5) the extension of the possibilities of the analytical investigation of differential equations of boundary value problems with the purpose of identifying the basic laws of optimum control and motion of SC; (6) improvement of the computational stability of the solution of boundary value problems; (7) a decrease in the required volume of computation.

Orientations of the Villas at Tylissos on Crete and their Relationships to the Minoan Calendar

NASA Astrophysics Data System (ADS)

Henriksson, Göran; Blomberg, Mary

2015-05-01

The two Late Minoan I villas at Tylissos and an unknown earlier building at the site show similar relationships to the celestial bodies that we have encountered at all of the Minoan buildings that we have studied. They had orientations to celestial events relevant to the calendar, such as sunrise or sunset at the equinoxes and the solstices, and the heliacal risings and settings of bright stars. We also re-encountered the phenomenon that different places marked the beginning of one or more solar months, which suggests that certain months had special relevance for specific places, as if to honor a god or goddess or some other special event for that particular place. In addition, the orientations of the two Late Minoan I villas at Tylissos share the same complexity that we have met at two other sites, where diagonal lines were used to create shadows when marking the parts of the calendar that were specific for Tylissos. It now seems clear that an element of Minoan cosmology insisted on a close connection between their places on earth and the celestial sphere. It was the custom for the Mycenaeans and the Greeks, who later inhabited the island, to honor their deities in special months, and we may find the roots of this custom among the Minoans.

Application of an Evolution Strategy in Planetary Ephemeris Optimization

NASA Astrophysics Data System (ADS)

Mai, E.

2016-12-01

Classical planetary ephemeris construction comprises three major steps, which are performed iteratively: simultaneous numerical integration of coupled equations of motion of a multi-body system (propagator step), reduction of thousands of observations (reduction step), and optimization of various selected model parameters (adjustment step). This traditional approach is challenged by ongoing refinements in force modeling, e.g. inclusion of much more significant minor bodies, an ever-growing number of planetary observations, e.g. vast amount of spacecraft tracking data, etc. To master the high computational burden and in order to circumvent the need for inversion of huge normal equation matrices, we propose an alternative ephemeris construction method. The main idea is to solve the overall optimization problem by a straightforward direct evaluation of the whole set of mathematical formulas involved, rather than to solve it as an inverse problem with all its tacit mathematical assumptions and numerical difficulties. We replace the usual gradient search by a stochastic search, namely an evolution strategy, the latter of which is also perfect for the exploitation of parallel computing capabilities. Furthermore, this new approach enables multi-criteria optimization and time-varying optima. This issue will become important in future once ephemeris construction is just one part of even larger optimization problems, e.g. the combined and consistent determination of the physical state (orbit, size, shape, rotation, gravity,…) of celestial bodies (planets, satellites, asteroids, or comets), and if one seeks near real-time solutions. Here we outline the general idea and discuss first results. As an example, we present a simultaneous optimization of high-correlated asteroidal ring model parameters (total mass and heliocentric radius), based on simulations.

The first Messenger data supporting main theses of the wave planetology

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2008-09-01

The first fundamental statement of the wave planetology [1-6 & others] is about ubiquity of tectonic dichotomy. All celestial bodies move, as it was established by I. Kepler, in non-round but elliptical orbits. This means that they all notwithstanding their sizes, masses, physical states and chemical compositions have alternating increasing and decreasing accelerations producing forces (Newton: F = m·a) warping celestial bodies. This wave warping rotating bodies (but all bodies rotate!) is decomposed into four orthogonal and diagonal directions of standing waves. An interference of these directions gives tectonic blocks of three kinds: uplifting (+), subsiding (-) and neutral (0). The block sizes depend on warping wavelengths. The fundamental wave long 2πR (R - a body radius) is present in all bodies thus making one hemisphere rising and the opposite one falling (more precise relation is 1/3 to 2/3 or 2/3 to 1/3). A geometrical proof of this relation is given in [6] where two famous tectonic dichotomies of Earth and Mars were explained by one wave reason. This ubiquitous phenomenon was described as the first theorem of the wave planetology: "Celestial bodies are dichotomous". There are many examples proving it among planets, satellites and asteroids, even Sun is dichotomous. But up to recent time the studied partially Mercury's surface was not a good example of this phenomenon as not fully visible Caloris basin didn't show its real dimension. Now, after the Messenger flyby we know that it is about 1500 km in diameter, that is about 1/3 of the Mercury's diameter and the rule is not violated. The third theorem of the wave planetary tectonics states: "Celestial bodies are granular". This means that celestial bodies are warped by individual waves lengths of which are inversely proportional to their orbital frequencies: higher frequency - finer granules, lower frequency - larger granules (Fig. 1). Observations fully support it not only in sense of granules diameters but also in granules amplitudes reflected in planetary relief range. It increases with the solar distances: Venus ~14, Earth ~20, Mars ~28-30 km. Without good topography on Mercury we theoretically assumed that this planet's relief range must be significantly lower (3-6 km) just to not violate the observed sequence (Fig. 2). The Messenger's measurements show that the real range does not exceed ~5 km. (small vertical relief differentiation is accompanied by small petrological differentiation expressed by a low albedo range, Fig. 2). One of Mercury's surprises is Caloris basin. Basins on planetary surfaces are normally lowlands filled with denser material (basalts for the terrestrial planets). Subsiding tectonic blocks - depressions - basins - occupying narrower and narrower space must be contracted, squeezed, wrinkled, rippled. This is confirmed in many occasions. But in the case of Caloris there is an extension confirmed by concentric and radial cracks. Uplifting and extending basin is a consequence of the wave tectonics. Waves have two phases (up and down) and a period after which the phases change. That is why initially subsided block - basin now (it started maybe a few milliards or hundreds millions years ago: the larger block - the longer wave phase period) experiences uplifting with extension. Is it the only case in the Solar system? Quite not. And Earth is a good example. Its southern mainly oceanic (thus subsided) hemisphere is filled with basalts, what is normal for planetary depressions. But precise geodynamic measurements show that the southern hemisphere increases lengths of its parallels that is expending. This dynamics is confirmed by widening modern planetary rifts in Atlantic, Indian ocean, Pacific in the southern direction and around Antarctic ("Southern" ocean) - a kind of the radial-concentric structure. A geochemical anomaly in oceanic basalts of this region ("DUPAL" anomaly after S.R. Hart, 1984) is characterized by relatively high Rb/Sr, Th/Pb, Th/U - a continental (uplifting) trend related to potassium enrichment. P. Castillo (1988) correlates this the largest mantle geochemical anomaly with a zone of decreased seismic velocities in the lower mantle - again decreased densities are tied to uplifting. The majority of hotspots are above the low velocity regions. Mesozoic continental flood basalts of the southern hemisphere (the Ferrar magmatic province) are low-Ti and high in Si, Rb/Sr, 87Sr/86Sr (initial 0. 707 - 0. 713)[7]. So, the shrunk planet due to cooling and important loss of volatiles [8] is no exception from the regular row of planets structurized by wave warping according to their solar distances.

A Celestial Reference Frame at X/ka-Band (8.4/32 Ghz) for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Garcia-Miro, C.; Horiuchi, S.; Romero-Wolf, A.; Snedeker, L.; Sotuela, I.

2012-01-01

Deep space tracking and navigation are done in a quasi-inertial reference frame based upon the angular positions of distant active galactic nuclei (AGN). These objects, which are found at extreme distances characterized by median redshifts of z = 1, are ideal for reference frame definition because they exhibit no measurable parallax or proper motion. They are thought to be powered by super massive black holes whose gravitational energy drives galactic sized relativistic jets. These jets produce synchrotron emissions which are detectable by modern radio techniques such as Very Long baseline Interferometry (VLBI).

High Energy Astronomy Observatory (HEAO)

NASA Image and Video Library

1975-01-01

The family of High Energy Astronomy Observatory (HEAO) instruments consisted of three unmarned scientific observatories capable of detecting the x-rays emitted by the celestial bodies with high sensitivity and high resolution. The celestial gamma-ray and cosmic-ray fluxes were also collected and studied to learn more about the mysteries of the universe. High-Energy rays cannot be studied by Earth-based observatories because of the obscuring effects of the atmosphere that prevent the rays from reaching the Earth's surface. They had been observed initially by sounding rockets and balloons, and by small satellites that do not possess the needed instrumentation capabilities required for high data resolution and sensitivity. The HEAO carried the instrumentation necessary for this capability. In this photograph, an artist's concept of three HEAO spacecraft is shown: HEAO-1, launched on August 12, 1977; HEAO-2, launched on November 13, 1978; and HEAO-3, launched on September 20. 1979.

Astronomy and catastrophes through myth and old texts.

NASA Astrophysics Data System (ADS)

Bon, E.; Ćirković, M.; Stojić, Igor; Gavrilović, Nataša

In the old myths and iconographies there are some motives that indicate at least one cataclysmic event that influenced many old religions and myths, that could be linked to the impact of the celestial object. We investigate the hypothesis of coherent catastrophism put forward in recent years by Clube, Bailey, Napier and others from both astrobiological and culturogical points of view. The conventional idea that the quasi-periodic break-up of celestial bodies influence terrestrial conditions can today be placed in both wider (astro-biological) and deeper (historico-culturological) context. In particular, we point out that the link between the Neolithic history of astronomy, and origin of Mithraism. We speculate that the main icon of Mithraic religion could pinpoint an event that happened around 4000 BC, when the spring equinox entered the constellation of Taurus. We also, link some motives in other old religions and myths to the same event, or to some similar events that inspired those myths.

Applications of laser ranging and VLBI observations for selenodetic control

NASA Technical Reports Server (NTRS)

Fajemirokun, F. A.

1971-01-01

The observation equations necessary to utilize lunar laser ranging and very long baseline interferometry measurements were developed for the establishment of a primary control network on the moon. The network consists of coordinates of moon points in the selenodetic Cartesian coordinate system, which is fixed to the lunar body, oriented along the three principal axes of inertia of the moon, and centered at the lunar center of mass. The observation equations derived are based on a general model in which the unknown parameters included: the selenodetic Cartesian coordinates, the geocentric coordinates of earth stations, parameters of the orientation of the selenodetic coordinate system with respect to a fixed celestial system, the parameters of the orientation of the average terrestrial coordinate system with respect to a fixed celestial coordinate system, and the geocentric coordinates of the center of mass of the moon, given by a lunar ephemeris.

The Story Behind Asteroid 14060 Patersonewen

NASA Astrophysics Data System (ADS)

Hatch, J. G.

2016-01-01

A pioneer of abstract art in Canada in the 1950s and 1960s, Paterson Ewen returned to figurative art by the end of the 1960s. After his divorce in 1968, the Montreal-born artist moved to London, Ontario, where he engaged in an emerging and vibrant national art scene, and started a new body of work depicting earthbound and celestial landscapes, which would dominate his visual career until his death in 2002. Many of these works are monumental in scale and were inspired by Japanese woodcuts; in fact, one of the most unique aspects of Ewen's work of this period is the method of their making that involves plywood as a support whose surface would be gouged by a router, often producing dramatic textural effects. Imagewise, Ewen produced one of the richest and most involved series of modern works inspired by celestial phenomena, ranging from Morehouse's comet and solar eruptions to the galaxy NGC 253.

The inspiration of astronomical phenomena (INSAP). Proceedings. Conference, Rocca di Papa (Italy), 27 Jun - 2 Jul 1994.

NASA Astrophysics Data System (ADS)

The papers concern the inspiration provided by astronomy to the fields of art, philosophy, religion and various human cultures. Individual papers cover the following topics: the Qur'anic conception of astronomical phenomena on Islamic civilization, the Milky Way and society, the mythology and ritual of India, the Varanasi Sun temples, celestial bodies meanings in pre-Hispanic Mexico, the celestial basis of civilization, Mexican eclipse imagery, Chinese dynastic ideology - astrological origins, NW Europe stone rows, stars and seasons in southern Africa, the Pleiades and Hesperides, stars and philosophy, the search for extraterrestrial life, the significance of the pre-Copernican revolution, Judaeo-Christian revelation, Maria Magdalena - the Morning Star, Chaucer's Canterbury Tales, stellar poetry, John Bauer's star-spangled fairy-tale world, Polish romantic poetry, the expansion of astronomical horizons, recent comet research and ancient sky implications, civilization Spenglerian model and punctuational crises, Anaxagoras and the scientist/laity interaction.

The analytical and numerical approaches to the theory of the Moon's librations: Modern analysis and results

NASA Astrophysics Data System (ADS)

Petrova, N.; Zagidullin, A.; Nefedyev, Y.; Kosulin, V.; Andreev, A.

2017-11-01

Observing physical librations of celestial bodies and the Moon represents one of the astronomical methods of remotely assessing the internal structure of a celestial body without conducting expensive space experiments. The paper contains a review of recent advances in studying the Moon's structure using various methods of obtaining and applying the lunar physical librations (LPhL) data. In this article LPhL simulation methods of assessing viscoelastic and dissipative properties of the lunar body and lunar core parameters, whose existence has been recently confirmed during the seismic data reprocessing of ;Apollo; space mission, are described. Much attention is paid to physical interpretation of the free librations phenomenon and the methods for its determination. In the paper the practical application of the most accurate analytical LPhL tables (Rambaux and Williams, 2011) is discussed. The tables were built on the basis of complex analytical processing of the residual differences obtained when comparing long-term series of laser observations with the numerical ephemeris DE421. In the paper an efficiency analysis of two approaches to LPhL theory is conducted: the numerical and the analytical ones. It has been shown that in lunar investigation both approaches complement each other in various aspects: the numerical approach provides high accuracy of the theory, which is required for the proper processing of modern observations, the analytical approach allows to comprehend the essence of the phenomena in the lunar rotation, predict and interpret new effects in the observations of lunar body and lunar core parameters.

“What Women Like”: Influence of Motion and Form on Esthetic Body Perception

PubMed Central

Cazzato, Valentina; Siega, Serena; Urgesi, Cosimo

2012-01-01

Several studies have shown the distinct contribution of motion and form to the esthetic evaluation of female bodies. Here, we investigated how variations of implied motion and body size interact in the esthetic evaluation of female and male bodies in a sample of young healthy women. Participants provided attractiveness, beauty, and liking ratings for the shape and posture of virtual renderings of human bodies with variable body size and implied motion. The esthetic judgments for both shape and posture of human models were influenced by body size and implied motion, with a preference for thinner and more dynamic stimuli. Implied motion, however, attenuated the impact of extreme body size on the esthetic evaluation of body postures, while body size variations did not affect the preference for more dynamic stimuli. Results show that body form and action cues interact in esthetic perception, but the final esthetic appreciation of human bodies is predicted by a mixture of perceptual and affective evaluative components. PMID:22866044

Modelling resonances of the standing body exposed to vertical whole-body vibration: Effects of posture

NASA Astrophysics Data System (ADS)

Subashi, G. H. M. J.; Matsumoto, Y.; Griffin, M. J.

2008-10-01

Lumped parameter mathematical models representing anatomical parts of the human body have been developed to represent body motions associated with resonances of the vertical apparent mass and the fore-and-aft cross-axis apparent mass of the human body standing in five different postures: 'upright', 'lordotic', 'anterior lean', 'knees bent', and 'knees more bent'. The inertial and geometric parameters of the models were determined from published anthropometric data. Stiffness and damping parameters were obtained by comparing model responses with experimental data obtained previously. The principal resonance of the vertical apparent mass, and the first peak in the fore-and-aft cross-axis apparent mass, of the standing body in an upright posture (at 5-6 Hz) corresponded to vertical motion of the viscera in phase with the vertical motion of the entire body due to deformation of the tissues at the soles of the feet, with pitch motion of the pelvis out of phase with pitch motion of the upper body above the pelvis. Upward motion of the body was in phase with the forward pitch motion of the pelvis. Changing the posture of the upper body had minor effects on the mode associated with the principal resonances of the apparent mass and cross-axis apparent mass, but the mode changed significantly with bending of the legs. In legs-bent postures, the principal resonance (at about 3 Hz) was attributed to bending of the legs coupled with pitch motion of the pelvis in phase with pitch motion of the upper body. In this mode, extension of the legs was in phase with the forward pitch motion of the upper body and the upward vertical motion of the viscera.

HIPPARCOS satellite: Aeritalia involvement and system test activities and results

NASA Astrophysics Data System (ADS)

Strim, B.; Cugno, W.; Morsillo, G.

In 1989 the European Space Agency is scheduled to launch HIPPARCOS on a 2.5-year mission that will revolutionize the state of astronomy. This is the first satellite to be dedicated to astrometry, a branch of astronomy that deals with the position of celestial objects and their motion in space. With an accuracy impossible to achieve from Earth, HIPPARCOS will make position, trigonometric parallax and proper motion measurements of some 100.000 pre-selected stars. The data will be used to calculate each star's distance and motion, providing astronomers with an unprecedented map of the heavens. In the end, the HIPPARCOS mission is expected to reveal surprisingly new insight into theories of stellar evolution, as well as into the nature of our galaxy and the universe. The program has been awarded to the MESH industrial consortium for definition, development and production. The French firm MATRA (prime contractor) and the AERITALIA SPACE SYSTEMS GROUP (major co-contractor) share program responsibility. AERITALIA is in charge of the spacecraft or "service module". This is the structural platform for the telescope payload and provides all subsystem services including thermal control, data handling, telecommunications, electrical power distribution, power generation, attitude and orbit control, and apogee kick motor. AERITALIA is responsible for the procurement of all spacecraft subsystems for which it directs the activities of a multinational team of subcontractors. In addition, it is in charge of the satellite's final assembly, integration and testing, as well as for the procurement of all ground support equipment for satellite testing. HIPPARCOS stands for HIgh Precision PARallax COllecting Satellite. Its name is also intended to honor the Greek astronomer Hipparchus (190-120 BC) who compiled the first star catalog and who first used trigonometric parallax to calculate the distance to the moon. (Parallax is the apparent shift in a celestial body's position in the sky when observed from two different points, for example, from two different points in the Earth's orbit around the sun. Distance can be calculated using parallax measurements). The satellite payload is a Schmidt reflecting telescope with two openings 58 degrees apart. The design allows stars in two different parts of the sky to be observed at the same time. Internally, the two fields of view are combined and the angular separation between pairs of stars - one star from each field of view - is recorded. Over the 2.5-year life of the HIPPARCOS mission, millions of such measurements between star pairs as faint as magnitude 13 will be made covering the entire celestial sphere. The data will be compiled into the HIPPARCOS catalog. The accuracy of these measurements for most of the stars is expected to be within 0.002 arcsec, an improvement of about a factor of 20 over ground-based observations. A second experiment, called TYCHO, will collect position and photometric data on about 400.000 stars. Although less accurate than the main experiment, TYCHO will provide astronomers with a reference catalog for a large number of stars. Both the HIPPARCOS and TYCHO star catalogs are expected to be available to the worldwide astronomical community by around 1994. The launch weight of HIPPORCOS is 1.140 kg. It will be put into geostationary orbit by an Ariane rocket. Purpose of the present paper is to put the spotlight on the system tests performed on the Satellite Structural Thermal Model STM, the Engineering Model EM and to summarize the main results so far obtained. A description of the System and Spacecraft design to better understand the mission and system requirements is also presented.

Military Space Mission Design and Analysis in a Multi-Body Environment: An Investigation of High-Altitude Orbits as Alternative Transfer Paths, Parking Orbits for Reconstitution, and Unconventional Mission Orbits

DTIC Science & Technology

2017-03-23

Dynamical Astronomy , vol. 90, no. January 2004, pp. 165–178, 2004. [Online]. Available: https://www.researchgate.net/publication/ 225231299 On The...Celestial Mechanics and Dynamical Astronomy , vol. 32, no. 1, pp. 53–71, 1984. [Online]. Available: https://engineering.purdue.edu/people/kathleen.howell

An International Parallax Campaign to Measure Distance to the Moon and Mars

ERIC Educational Resources Information Center

Cenadelli, D.; Zeni, M.; Bernagozzi, A.; Calcidese, P.; Ferreira, L.; Hoang, C.; Rijsdijk, C.

2009-01-01

Trigonometric parallax is a powerful method to work out the distance of celestial bodies, and it was used in the past to measure the distance of the Moon, Venus, Mars and nearby stars. We set up an observation campaign for high school and undergraduate students with the purpose to measure both the Moon's and Mars' parallax. To have a large enough…

From Hipparcos to Gaia

NASA Astrophysics Data System (ADS)

Eyer, L.; Dubath, P.; Saesen, S.; Evans, D. W.; Wyrzykowski, L.; Hodgkin, S.; Mowlavi, N.

2012-04-01

The measurement of the positions, distances, motions and luminosities of stars represents the foundations of modern astronomical knowledge. Launched at the end of the eighties, the ESA Hipparcos satellite was the first space mission dedicated to such measurements. Hipparcos improved position accuracies by a factor of 100 compared to typical ground-based results and provided astrometric and photometric multi-epoch observations of 118,000 stars over the entire sky. The impact of Hipparcos on astrophysics has been extremely valuable and diverse. Building on this important European success, the ESA Gaia cornerstone mission promises an even more impressive advance. Compared to Hipparcos, it will bring a gain of a factor 50 to 100 in position accuracy and of a factor of 10,000 in star number, collecting photometric, spectrophotometric and spectroscopic data for one billion celestial objects. During its 5-year flight, Gaia will measure objects repeatedly, up to a few hundred times, providing an unprecedented database to study the variability of all types of celestial objects. Gaia will bring outstanding contributions, directly or indirectly, to most fields of research in astrophysics, such as the study of our Galaxy and of its stellar constituents, and the search for planets outside the solar system.

A Study for the Restoration of Hong Dae-Yong Honsangui - Focusing on the structure and operating mechanism

NASA Astrophysics Data System (ADS)

Lee, Yong Sam; Kim, Sang Hyuk; Park, Je Hoon

2013-09-01

Honsangui (celestial globe) which is a water-hammering method astronomical clock is recorded in "Juhaesuyong" which is Volume VI of supplement from "Damheonseo", written by Hong Dae-Yong (1731~1783). We made out the conceptual design of Hong Dae-Yong's Honsangui through the study on its structure and working mechanism. Honsangui consist of three rings and two layers, the structure of rings which correspond to outer layer is similar to his own Tongcheonui (armillary sphere) which is a kind of armillary sphere. Honsang sphere which correspond to inner layer depicts constellations and milky way and two beads hang on it as Sun and Moon respectively for realize the celestial motion. Tongcheonui is operated by the pendulum power but Honsangui is operated by water-hammering method mechanism. This Honsangui's working mechanism is the traditional way of Joseon and it was simplified the working mechanism of Shui y'n i hsiang t'ai which is a representative astronomical clock of China. This record of Honsangui is the only historical record about the water-hammering method working mechanism of Joseon Era and it provide the study of water-hammering method mechanism with a vital clue.

Radiowaves and Tectonic Dichotomy: Two Sides of One Coin

NASA Astrophysics Data System (ADS)

Kochemasov, G.

The first theorem of the wave planetology states that "Celestial bodies are di- chotomic"[1]. This notion is best demonstrated by modulation of the high frequency orbiting in the Solar system (SS) by the low frequency orbiting the SS in Galaxy. Or- biting frequencies of all bodies in the SS -from 1/8 hours for Phobos to 1/248 years for Pluto - are high comparative to the SS orbiting in Galaxy -about 1/200 000 000 years. Modulation of a high frequency by a low frequency brings about side frequencies at both sides of a high frequency. Earlier we considered only one side of the modula- tion stressing that the lower side frequency in any celestial body can achieve only the fundamental wave and produce related to it inevitable tectonic dichotomy [2]. Now we consider the higher side frequencies and find that they are in the limits of the ra- dio frequencies. Dividing all possible orbiting frequencies of bodies in the SS by the SS orbiting frequency in Galaxy one comes to a range of side frequencies from mi- crowaves to kilometer waves. This finding is rather important as it is well known that all bodies of the SS emit often enigmatic radiowaves. Figuratively, the SS is wrapped by a cloud of crossing radiowaves of various frequencies. Some calculations below show modulation of tectonic granula sizes of some celestial bodies. A granula size is a half of a wavelength which is tied to an orbiting frequency. A scale is the Earth's orbiting period 1 year and the granula size pR/4. The tectonic granula sizes of bodies are proportional to their orbital periods (Theorem 3 [1[). The modulating frequency is 1/200 000 000 years. Jupiter (12 y : 200 000 000 y) pR= (12 : 200 000 000) 3.14°u 71400 km=13.4 m tectonic granula or 26.8 m wavelength. Varying orbital periods and bodies'radia one comes to the following wavelengths. Jupiter-26.8 m, Saturn-56.4 m, Uranus-67 m, Neptune-124 m, Pluto-10.9 m, Sun-1.46 m, Triton-11.4 m (for the cir- cumsolar frequency), 1.84 mm (circumneptunian fr.), Amalthea-4.88 cm (circumsolar fr.), 0.0028 mm (circumjovian fr.), the Moon-5.46 cm (circumsolar fr.), 0.46 cm (cir- cumterrestrial fr.) [3]. This range of frequencies (infrared-kilometer waves) is typical for the SS. Within it surely there are waves of other modulations, harmonics, reso- nances. Extra heat emissions of Amalthea, Io, Triton could be related to microwave and infrared emissions (oscillations). References. [1] Kochemasov G.G.(1999) Geophys. Res. Abstr., v.1, #3.700; [2]Kochemasov G.G. (2000) 32nd Vernadsky-Brown microsymp. on comparative planetology, Abstr.,Moscow, 88-89; [3]Kochemasov G.G. (2001) 34th Vernadsky-Brown microsymp. Topics in comparative planetology, Ab- str., Moscow,(CD-ROM).

Observation of Celestial Phenomena in Ancient China

NASA Astrophysics Data System (ADS)

Sun, Xiaochun

Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

Subsidence of the South Polar Terrain and global tectonic of Enceladus

NASA Astrophysics Data System (ADS)

Czechowski, Leszek

2016-04-01

Introduction: Enceladus is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of ˜200 kg is ejected into space from the South Polar Terrain (SPT) - [1]. The loss of matter from the body's interior should lead to global compression of the crust (like on Mercury). Typical effects of compression are: thrust faults, folding and subduction. However, such forms are not dominant on Enceladus. We propose here special dynamical process that could explain this paradox. Our hypothesis states that the mass loss from SPT is the main driving mechanism of the following tectonic processes: subsidence of SPT, flow in the mantle and motion of adjacent tectonic plates. The hypothesis is presented in [2] and [3]. We suggest that the loss of the volatiles results in a void, an instability, and motion of solid matter to fill the void. The motion includes: Subsidence of the 'lithosphere' of SPT. Flow of the matter in the mantle. Motion of plates adjacent to SPT towards the active region. Methods and results: The numerical model of the subsidence process is developed. It is based on the model of thermal convection in the mantle. Special boundary conditions are applied, that could simulate subsidence of SPT. If emerging void is being filled by the subsidence of SPT only, then the velocity of subsidence is ˜0.05 mmṡyr-1. However, numerical calculations indicate that all three types of motion are usually important. The role of a given motion depends on the viscosity distribution. Generally, for most of the models the subsidence is ˜0.02 mmṡyr-1, but mantle flow and plates' motion also play a role in filling the void. The preliminary results of the numerical model indicate also that the velocity of adjacent plates could be ˜0.02 mmṡyr-1 for the Newtonian rheology. Note that in our model the reduction of the crust area is not a result of compression but it is a result of the plate sinking. Therefore the compressional surface features do not have to be dominant. The SPT is compressed, so "tiger stripes" could exist for long time. Only after significant subsidence (below 1200 m) the regime of stresses changes to compressional. We suppose that it means the end of activity in a given region. Acknowledgments This work was partially supported by the National Science Centre (grant 2011/01/B/ST10/06653). Computer resources of Interdisciplinary Centre for Mathematical and Computational Modeling of University of Warsaw were also used in the research References [1] Spencer, J. R., et al. (2009) Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer Science, p. 683. [2] Czechowski L. (2015) Mass loss as a driving mechanism of tectonics of Enceladus 46th Lunar and Planetary Science Conference 2030.pdf. [3] Czechowski, L., (2014) Some remarks on the early evolution of Enceladus. Planet. Sp. Sc. 104, 185-199.

George William Hill, the Great but Unknown 19th Century Celestial Mechanician

NASA Astrophysics Data System (ADS)

Corbin, Brenda G.

2012-01-01

George William Hill (1838-1914) has long been considered one of the most famous and talented celestial mechanicians of the past century and a half. However, many people have never heard of him and his work. Simon Newcomb said he "will easily rank as the greatest master of mathematical astronomy during the last quarter of the nineteenth century.” After receiving a B.A. at Rutgers in 1859, Hill began work in 1861 at the office of the American Ephemeris and Nautical Almanac in Cambridge, MA. He moved to Washington with the group in 1882 which then became part of the U. S. Naval Observatory. Newcomb, beginning his work on planetary motion, assigned the theory of Jupiter and Saturn to him, calling it about the most difficult topic. Hill's work was published by the USNO in 1890 as A New Theory of Jupiter and Saturn. From 1898 to 1901, Hill lectured on the subject of celestial mechanics at Columbia University in a position created just for him. After 1892 and until his death, he lived at the family homestead in West Nyack, NY. He never married, was something of a recluse, and spent most of his time with his books and research. Hill was an amateur botanist and enjoyed exploring on long walks in the countryside. Many honors and awards came to him during his lifetime, both from the U.S. and abroad, including serving as president of the American Mathematical Society. All of Hill's mathematical and astronomical research was incorporated in The Collected Mathematical Works of George William Hill. This work, containing a preface in French by Poincare, was published in 4 large volumes by the Carnegie Institution of Washington in 1905.

Heavenly Bodies and Phenomena in Petroglyphs

NASA Astrophysics Data System (ADS)

Tokhatyan, Karen

2016-12-01

In Armenian culture are amply reflected realities connected with Universe. Their figurative expressions are also petroglyphs in which there are representations of solar signs, swastika, Moon crescend, planets, stars, star groups, constellations, Milky Way, Earth. Among heavenly and atmospheric phenomena are: eclipce, meteor, comet, ligthning, cloud, rain and rainbow. There are many products of scientific thinking: stellar maps, calendars, compasses, astronomical records, Zodiac signs and ideograms. Thousands of the Armenian petroglyphs that were created millennia ago by an indigenous ethnos - Armenians, point to the significant place of celestial bodies and luminaries, especially the Sun, stars, and stellar constellations in our ancestors' cosmological perceptions.

Earth: Physico-mathematical Meaning of "primary" and "secondary" Oceans Conception

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Geologists term the Pacific ocean "primary" and Atlantic and Indian oceans "sec- ondary" meaning that the first is larger, deeper, older (?) and plays more fundamental role in the Earth's tectonics. The wave planetology as hierarchically higher than geol- ogy (Earth is only one of planets and of many celestial bodies), states that all celestial bodies are dichotomic ( "Pacific" as a tectonic feature is found in any celestial body) and sectoral (i.g., the Arctic-Antarctic symptom is also in any body) (Theorems 1, 2 [1]). The tectonic dichotomy and sectoring are related to the first and second harmon- ica (wave1 and wave2) of warping standing waves appearing in any body just because they move in non-circular (elliptic, parabolic) orbits and hence inertia forces tend to distort original shapes. This disfiguring of a rotating body is not just a superficial fea- ture, it involves fundamental changes in the entire vertical section above and below surface rises and falls (Theorem 4 [1]). Here acts the law of angular momentum equi- libration. Thus, under the Pacific basin hollow -the deepest hollow produced by wave1 - mantle is denser than under the Atlantic and Indian oceanic basins - basins produced by wave2. We know it because squeezed out of mantle tholeiites in the mid-oceanic ridges are Fe-richer in Pacific than in other oceans. The "primary" ocean is thus a fundamental or "wave1" or 2pR-structure. The "secondary" oceans are "wave2" or pR-structures. pR-structures represented by continents, secondary oceans and basins and the "superswell" (Darwin rise) in the Pacific, i.e. by most important terrestrial lithospheric tectonic blocks, are distributed on the Earth's surface not randomly. As must be expected of the standing wave interference picture, the pR-structure pattern shows regular grouping around certain centres. There are 6 centres - vertices of an oc- tahedron occurring at equator (1, 2), tropics (3, 4) and polar circles (5, 6). They are: 1. New Guinea, 2. Equatorial Atlantic, 3. Easter Isl., 4. the Pamirs-Hindukush, 5. Bering Strait, 6. Bouvet Isl. There is expected antipodality between 1-2, 3-4, 5-6. The vertices of the structural octahedron combine around them sectors by a similar algorithm: there always converge two opposite differently uplifted sectors separated by two differently 1 subsided sectors. I.g., around the Pamirs-Hindukush there are two uplifted sectors: African (++) Asian (+), and two separating them subsided ones: Eurasian (-) Indo- ceanic (- -). The cosmically oriented structural octahedron and other regularities show that the wave induced structurization is a real predominant factor in planetology. Ref. [1] Kochemasov G.G.(1999) Geophys.Res.Abstr., v.1, 3, 700. 2

A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.

2007-12-17

We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and Kuiper Belt strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. If detected, the {gamma}-ray emission by the Mainmore » Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic {gamma}-ray emission. Additionally, it can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions, and the mass spectrum of small bodies in the Main Belt and Kuiper Belt. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center.« less

The PMA Catalogue: 420 million positions and absolute proper motions

NASA Astrophysics Data System (ADS)

Akhmetov, V. S.; Fedorov, P. N.; Velichko, A. B.; Shulga, V. M.

2017-07-01

We present a catalogue that contains about 420 million absolute proper motions of stars. It was derived from the combination of positions from Gaia DR1 and 2MASS, with a mean difference of epochs of about 15 yr. Most of the systematic zonal errors inherent in the 2MASS Catalogue were eliminated before deriving the absolute proper motions. The absolute calibration procedure (zero-pointing of the proper motions) was carried out using about 1.6 million positions of extragalactic sources. The mean formal error of the absolute calibration is less than 0.35 mas yr-1. The derived proper motions cover the whole celestial sphere without gaps for a range of stellar magnitudes from 8 to 21 mag. In the sky areas where the extragalactic sources are invisible (the avoidance zone), a dedicated procedure was used that transforms the relative proper motions into absolute ones. The rms error of proper motions depends on stellar magnitude and ranges from 2-5 mas yr-1 for stars with 10 mag < G < 17 mag to 5-10 mas yr-1 for faint ones. The present catalogue contains the Gaia DR1 positions of stars for the J2015 epoch. The system of the PMA proper motions does not depend on the systematic errors of the 2MASS positions, and in the range from 14 to 21 mag represents an independent realization of a quasi-inertial reference frame in the optical and near-infrared wavelength range. The Catalogue also contains stellar magnitudes taken from the Gaia DR1 and 2MASS catalogues. A comparison of the PMA proper motions of stars with similar data from certain recent catalogues has been undertaken.

Multibody Simulation Software Testbed for Small-Body Exploration and Sampling

NASA Technical Reports Server (NTRS)

Acikmese, Behcet; Blackmore, James C.; Mandic, Milan

2011-01-01

G-TAG is a software tool for the multibody simulation of a spacecraft with a robotic arm and a sampling mechanism, which performs a touch-and-go (TAG) maneuver for sampling from the surface of a small celestial body. G-TAG utilizes G-DYN, a multi-body simulation engine described in the previous article, and interfaces to controllers, estimators, and environmental forces that affect the spacecraft. G-TAG can easily be adapted for the analysis of the mission stress cases to support the design of a TAG system, as well as for comprehensive Monte Carlo simulations to analyze and evaluate a particular TAG system design. Any future small-body mission will benefit from using G-TAG, which has already been extensively used in Comet Odyssey and Galahad Asteroid New Frontiers proposals.

Insect Responses to Linearly Polarized Reflections: Orphan Behaviors Without Neural Circuits.

PubMed

Heinloth, Tanja; Uhlhorn, Juliane; Wernet, Mathias F

2018-01-01

The e-vector orientation of linearly polarized light represents an important visual stimulus for many insects. Especially the detection of polarized skylight by many navigating insect species is known to improve their orientation skills. While great progress has been made towards describing both the anatomy and function of neural circuit elements mediating behaviors related to navigation, relatively little is known about how insects perceive non-celestial polarized light stimuli, like reflections off water, leaves, or shiny body surfaces. Work on different species suggests that these behaviors are not mediated by the "Dorsal Rim Area" (DRA), a specialized region in the dorsal periphery of the adult compound eye, where ommatidia contain highly polarization-sensitive photoreceptor cells whose receptive fields point towards the sky. So far, only few cases of polarization-sensitive photoreceptors have been described in the ventral periphery of the insect retina. Furthermore, both the structure and function of those neural circuits connecting to these photoreceptor inputs remain largely uncharacterized. Here we review the known data on non-celestial polarization vision from different insect species (dragonflies, butterflies, beetles, bugs and flies) and present three well-characterized examples for functionally specialized non-DRA detectors from different insects that seem perfectly suited for mediating such behaviors. Finally, using recent advances from circuit dissection in Drosophila melanogaster , we discuss what types of potential candidate neurons could be involved in forming the underlying neural circuitry mediating non-celestial polarization vision.

Toolkits Control Motion of Complex Robotics

NASA Technical Reports Server (NTRS)

2010-01-01

That space is a hazardous environment for humans is common knowledge. Even beyond the obvious lack of air and gravity, the extreme temperatures and exposure to radiation make the human exploration of space a complicated and risky endeavor. The conditions of space and the space suits required to conduct extravehicular activities add layers of difficulty and danger even to tasks that would be simple on Earth (tightening a bolt, for example). For these reasons, the ability to scout distant celestial bodies and perform maintenance and construction in space without direct human involvement offers significant appeal. NASA has repeatedly turned to complex robotics for solutions to extend human presence deep into space at reduced risk and cost and to enhance space operations in low Earth orbit. At Johnson Space Center, engineers explore the potential applications of dexterous robots capable of performing tasks like those of an astronaut during extravehicular activities and even additional ones too delicate or dangerous for human participation. Johnson's Dexterous Robotics Laboratory experiments with a wide spectrum of robot manipulators, such as the Mitsubishi PA-10 and the Robotics Research K-1207i robotic arms. To simplify and enhance the use of these robotic systems, Johnson researchers sought generic control methods that could work effectively across every system.

Comparing the efficiency of methods for the calculation of intermediate perturbed orbit from range and range rate measurements at three times. (Russian Title: Сравнение эффективности методов вычисления промежуточной возмущенной орбиты по измерениям дальности и скорости ее изменения в три момента времени)

NASA Astrophysics Data System (ADS)

Shefer, V. A.; Ivanov, I. V.; Koksin, A. M.

2013-07-01

Two methods that the first author developed for finding the orbit of a small celestial body from three pairs of range and range rate observations are applied to the determination of orbits of some artificial Earth satellites. The efficiency of using these methods is investigated in comparison with the commonly used procedure based on the construction of the unperturbed Keplerian orbit. The comparison shows that the methods proposed are an efficient means for studying perturbed motion.

Minimal energy configurations of gravitationally interacting rigid bodies

NASA Astrophysics Data System (ADS)

Moeckel, Richard

2017-05-01

Consider a collection of n rigid, massive bodies interacting according to their mutual gravitational attraction. A relative equilibrium motion is one where the entire configuration rotates rigidly and uniformly about a fixed axis in R^3. Such a motion is possible only for special positions and orientations of the bodies. A minimal energy motion is one which has the minimum possible energy in its fixed angular momentum level. While every minimal energy motion is a relative equilibrium motion, the main result here is that a relative equilibrium motion of n≥3 disjoint rigid bodies is never an energy minimizer. This generalizes a known result about point masses to the case of rigid bodies.

Special Software for Planetary Image Processing and Research

NASA Astrophysics Data System (ADS)

Zubarev, A. E.; Nadezhdina, I. E.; Kozlova, N. A.; Brusnikin, E. S.; Karachevtseva, I. P.

2016-06-01

The special modules of photogrammetric processing of remote sensing data that provide the opportunity to effectively organize and optimize the planetary studies were developed. As basic application the commercial software package PHOTOMOD™ is used. Special modules were created to perform various types of data processing: calculation of preliminary navigation parameters, calculation of shape parameters of celestial body, global view image orthorectification, estimation of Sun illumination and Earth visibilities from planetary surface. For photogrammetric processing the different types of data have been used, including images of the Moon, Mars, Mercury, Phobos, Galilean satellites and Enceladus obtained by frame or push-broom cameras. We used modern planetary data and images that were taken over the years, shooting from orbit flight path with various illumination and resolution as well as obtained by planetary rovers from surface. Planetary data image processing is a complex task, and as usual it can take from few months to years. We present our efficient pipeline procedure that provides the possibilities to obtain different data products and supports a long way from planetary images to celestial body maps. The obtained data - new three-dimensional control point networks, elevation models, orthomosaics - provided accurate maps production: a new Phobos atlas (Karachevtseva et al., 2015) and various thematic maps that derived from studies of planetary surface (Karachevtseva et al., 2016a).

Proposal MaMBA - Moon and Mars Base Analog

NASA Astrophysics Data System (ADS)

Heinicke, Christiane; Foing, Bernard

2017-04-01

Despite impressive progress in robotic exploration of celestial bodies, robots are believed to never reach the effectiveness and efficiency of a trained human. Consequently, ESA proposes to build an international Moon Village in roughly 15 years and NASA plans for the first manned mission to Mars shortly after. One of the challenges still remaining is the need for a shelter, a habitat which allows human spacefarers to safely live and work on the surface of a celestial body. Although various prototype habitats have been built and inhabited during the last decade, they typically share two fundamental flaws: First, they usually consist of a single space, which may become uninhabitable after depressurization due to just one single catastrophic event. Second, none of the habitats provides shielding against radiation, one of the major health concerns for spacefaring crews. Project MaMBA will address these two problems at the root and build an underground habitat comprised of five connected, but independent modules. The habitat will serve for testing technologies like life support, power systems, and interplanetary communication. Special attention will be given to the development of the geoscience laboratory module. In addition to the technological aspects, the envisioned habitat will serve as a unique test ground for studies on the effects of underground habitation on a crew.

On the existence of another source of heat production for the earth and planets, and its connection with gravitomagnetism.

PubMed

Elbeze, Alexandre Chaloum

2013-01-01

Recent revised estimates of the Earth's surface heat flux are in the order of 47 TW. Given that its internal radiogenic (mantle and crust) heat production is estimated to be around 20 TW, the Earth has a thermal deficit of around 27 TW. This article will try to show that the action of the gravitational field of the Sun on the rotating masses of the Earth is probably the source of another heat production in order of 54TW, which would satisfy the thermal balance of our celestial body and probably explain the reduced heat flow Qo. We reach this conclusion within the framework of gravitation implied by Einstein's special and general relativity theory (SR, GR). Our results show that it might possible, in principle, to calculate the heat generated by the action of the gravitational field of celestial bodies on the Earth and planets of the Solar System (a phenomenon that is different to that of the gravitational tidal effect from the Sun and the Moon). This result should help physicists to improve and develop new models of the Earth's heat balance, and suggests that contrary to cooling, the Earth is in a phase of thermal balance, or even reheating.

Synthesis of a controller for stabilizing the motion of a rigid body about a fixed point

NASA Astrophysics Data System (ADS)

Zabolotnov, Yu. M.; Lobanov, A. A.

2017-05-01

A method for the approximate design of an optimal controller for stabilizing the motion of a rigid body about a fixed point is considered. It is assumed that rigid body motion is nearly the motion in the classical Lagrange case. The method is based on the common use of the Bellman dynamic programming principle and the averagingmethod. The latter is used to solve theHamilton-Jacobi-Bellman equation approximately, which permits synthesizing the controller. The proposed method for controller design can be used in many problems close to the problem of motion of the Lagrange top (the motion of a rigid body in the atmosphere, the motion of a rigid body fastened to a cable in deployment of the orbital cable system, etc.).

Copernicus, Epicurus, Galileo, and Gassendi.

PubMed

LoLordo, Antonia

2015-06-01

In his Letters on the motion impressed by a moving mover, the theory of the motion of composite bodies put forth by Gassendi is strikingly similar to Galileo's. In other of his writings, however, his description of the motion of individual atoms is understood very differently. In those places, he holds (1) that individual atoms are always in motion, even when the body that contains them is at rest, (2) that atomic motion is discontinuous although the motion of composite bodies is at least apparently continuous, and (3) that atomic motion is grounded in an intrinsic vis motrix, motive power. In contrast, composite bodies simply persist in their state of motion or rest in the absence of outside interference. Unfortunately, Gassendi neglects to explain how his accounts of atomic and composite motion fit together, and it is difficult to see how they could possibly be integrated. My goal is to explain, given this difficulty, why he accepted both the Galilean theory of the motion of composite bodies and the Epicurean theory of atomic motion. Copyright © 2015 Elsevier Ltd. All rights reserved.

A study of the nonlinear aerodynamics of bodies in nonplanar motion. Ph.D. Thesis - Stanford Univ., Calif.; [numerical analysis of aerodynamic force and moment systems during large amplitude, arbitrary motions

NASA Technical Reports Server (NTRS)

Schiff, L. B.

1974-01-01

Concepts from the theory of functionals are used to develop nonlinear formulations of the aerodynamic force and moment systems acting on bodies in large-amplitude, arbitrary motions. The analysis, which proceeds formally once the functional dependence of the aerodynamic reactions upon the motion variables is established, ensures the inclusion, within the resulting formulation, of pertinent aerodynamic terms that normally are excluded in the classical treatment. Applied to the large-amplitude, slowly varying, nonplanar motion of a body, the formulation suggests that the aerodynamic moment can be compounded of the moments acting on the body in four basic motions: steady angle of attack, pitch oscillations, either roll or yaw oscillations, and coning motion. Coning, where the nose of the body describes a circle around the velocity vector, characterizes the nonplanar nature of the general motion.

The onset of dynamical instability and chaos in navigation satellite orbits

NASA Astrophysics Data System (ADS)

Rosengren, Aaron Jay; Daquin, Jérôme; Alessi, Elisa Maria; Valsecchi, Giovanni B.; Rossi, Alessandro; Deleflie, Florent

2015-05-01

Orbital resonances are ubiquitous in the Solar System and are harbingers for the onset of dynamical instability and chaos. It has long been suspected that the Global Navigation Satellite Systems exist in a background of complex resonances and chaotic motion; yet, the precise dynamical character of these phenomena remains elusive. Here we will show that the same underlying physical mechanism, the overlapping of secular resonances, responsible for the eventual destabilization of Mercury and recently proposed to explain the orbital architecture of extrasolar planetary systems (Lithwick Y., Wu Y., 2014, PNAS; Batygin K., Morbidelli A., Holman M.J., 2015, ApJ) is at the heart of the orbital instabilities of seemingly more mundane celestial bodies---the Earth's navigation satellites. We will demonstrate that the occurrence and nature of the secular resonances driving these dynamics depend chiefly on one aspect of the Moon's perturbed motion, the regression of the line of nodes. This talk will present analytical models that accurately reflect the true nature of the resonant interactions, and will show how chaotic diffusion is mediated by the web-like structure of secular resonances. We will also present an atlas of FLI stability maps, showing the extent of the chaotic regions of the phase space, computed through a hierarchy of more realistic, and more complicated, models, and compare the chaotic zones in these charts with the analytical estimation of the width of the chaotic layers from the heuristic Chirikov resonance-overlap criterion. The obtained results have remarkable practical applications for space debris mitigation and for satellite technology, and are both of essential dynamical and theoretical importance, with broad implications for planetary science.

Orbital theory in terms of KS elements with luni-solar perturbations

NASA Astrophysics Data System (ADS)

Sellamuthu, Harishkumar; Sharma, Ram

2016-07-01

Precise orbit computation of Earth orbiting satellites is essential for efficient mission planning of planetary exploration, navigation and satellite geodesy. The third-body perturbations of the Sun and the Moon predominantly affect the satellite motion in the high altitude and elliptical orbits, where the effect of atmospheric drag is negligible. The physics of the luni-solar gravity effect on Earth satellites have been studied extensively over the years. The combined luni-solar gravitational attraction will induce a cumulative effect on the dynamics of satellite orbits, which mainly oscillates the perigee altitude. Though accurate orbital parameters are computed by numerical integration with respect to complex force models, analytical theories are highly valued for the manifold of solutions restricted to relatively simple force models. During close approach, the classical equations of motion in celestial mechanics are almost singular and they are unstable for long-term orbit propagation. A new singularity-free analytical theory in terms of KS (Kustaanheimo and Stiefel) regular elements with respect to luni-solar perturbation is developed. These equations are regular everywhere and eccentric anomaly is the independent variable. Plataforma Solar de Almería (PSA) algorithm and a Fourier series algorithm are used to compute the accurate positions of the Sun and the Moon, respectively. Numerical studies are carried out for wide range of initial parameters and the analytical solutions are found to be satisfactory when compared with numerically integrated values. The symmetrical nature of the equations allows only two of the nine equations to be solved for computing the state vectors and the time. Only a change in the initial conditions is required to solve the other equations. This theory will find multiple applications including on-board software packages and for mission analysis purposes.

General relativistic satellite astrometry. II. Modeling parallax and proper motion

NASA Astrophysics Data System (ADS)

de Felice, F.; Bucciarelli, B.; Lattanzi, M. G.; Vecchiato, A.

2001-07-01

The non-perturbative general relativistic approach to global astrometry introduced by de Felice et al. (\\cite{defetal}) is here extended to account for the star motions on the Schwarzschild celestial sphere. A new expression of the observables, i.e. angular distances among stars, is provided, which takes into account the effects of parallax and proper motions. This dynamical model is then tested on an end-to-end simulation of the global astrometry mission GAIA. The results confirm the findings of our earlier work, which applied to the case of a static (angular coordinates only) sphere. In particular, measurements of large arcs among stars (each measurement good to ~ 100 mu arcsec, as expected for V ~ 17 mag stars) repeated over an observing period comparable to the mission lifetime foreseen for GAIA, can be modeled to yield estimates of positions, parallaxes, and annual proper motions good to ~ 15 mu arcsec. This second round of experiments confirms, within the limitations of the simulation and the assumptions of the current relativistic model, that the space-born global astrometry initiated with Hipparcos can be pushed down to the 10-5 arcsec accuracy level proposed with the GAIA mission. Finally, the simplified case we have solved can be used as reference for testing the limiting behavior of more realistic models as they become available.

Emotion categorization of body expressions in narrative scenarios

PubMed Central

Volkova, Ekaterina P.; Mohler, Betty J.; Dodds, Trevor J.; Tesch, Joachim; Bülthoff, Heinrich H.

2014-01-01

Humans can recognize emotions expressed through body motion with high accuracy even when the stimuli are impoverished. However, most of the research on body motion has relied on exaggerated displays of emotions. In this paper we present two experiments where we investigated whether emotional body expressions could be recognized when they were recorded during natural narration. Our actors were free to use their entire body, face, and voice to express emotions, but our resulting visual stimuli used only the upper body motion trajectories in the form of animated stick figures. Observers were asked to perform an emotion recognition task on short motion sequences using a large and balanced set of emotions (amusement, joy, pride, relief, surprise, anger, disgust, fear, sadness, shame, and neutral). Even with only upper body motion available, our results show recognition accuracy significantly above chance level and high consistency rates among observers. In our first experiment, that used more classic emotion induction setup, all emotions were well recognized. In the second study that employed narrations, four basic emotion categories (joy, anger, fear, and sadness), three non-basic emotion categories (amusement, pride, and shame) and the “neutral” category were recognized above chance. Interestingly, especially in the second experiment, observers showed a bias toward anger when recognizing the motion sequences for emotions. We discovered that similarities between motion sequences across the emotions along such properties as mean motion speed, number of peaks in the motion trajectory and mean motion span can explain a large percent of the variation in observers' responses. Overall, our results show that upper body motion is informative for emotion recognition in narrative scenarios. PMID:25071623

Role of Alpha-Band Oscillations in Spatial Updating across Whole Body Motion

PubMed Central

Gutteling, Tjerk P.; Medendorp, W. P.

2016-01-01

When moving around in the world, we have to keep track of important locations in our surroundings. In this process, called spatial updating, we must estimate our body motion and correct representations of memorized spatial locations in accordance with this motion. While the behavioral characteristics of spatial updating across whole body motion have been studied in detail, its neural implementation lacks detailed study. Here we use electroencephalography (EEG) to distinguish various spectral components of this process. Subjects gazed at a central body-fixed point in otherwise complete darkness, while a target was briefly flashed, either left or right from this point. Subjects had to remember the location of this target as either moving along with the body or remaining fixed in the world while being translated sideways on a passive motion platform. After the motion, subjects had to indicate the remembered target location in the instructed reference frame using a mouse response. While the body motion, as detected by the vestibular system, should not affect the representation of body-fixed targets, it should interact with the representation of a world-centered target to update its location relative to the body. We show that the initial presentation of the visual target induced a reduction of alpha band power in contralateral parieto-occipital areas, which evolved to a sustained increase during the subsequent memory period. Motion of the body led to a reduction of alpha band power in central parietal areas extending to lateral parieto-temporal areas, irrespective of whether the targets had to be memorized relative to world or body. When updating a world-fixed target, its internal representation shifts hemispheres, only when subjects’ behavioral responses suggested an update across the body midline. Our results suggest that parietal cortex is involved in both self-motion estimation and the selective application of this motion information to maintaining target locations as fixed in the world or fixed to the body. PMID:27199882

Transformation of Elastic Wave Energy to the Energy of Motion of Bodies

NASA Astrophysics Data System (ADS)

Vesnitskiĭ, A. I.; Lisenkova, E. E.

2002-01-01

The motion of a body along an elastic guide under the effect of an incident wave is considered. An equation describing the longitudinal motion of a body along an arbitrary guide is derived from the laws governing the energy and momentum variations for the case when the incident wave generates a single reflected wave. The equations that describe the motion of a body along a string and along a beam corresponding to the Bernoulli-Euler model are considered as examples. The process of the body acceleration along a beam of the aforementioned type is investigated. For the subcritical velocities, the law governing the motion of the body and the ratio of the kinetic energy variation to the energy supplied to the body are determined.

a Numerical Study of Close Approaches for a Cloud of Debris Considering Atmospheric Drag and Lift

NASA Astrophysics Data System (ADS)

Gomes, Vivian; Golebiewska, Justyna; Prado, Antonio

The present paper study close approaches between a group of debris and a planet. The dynamical model considers the atmosphere of the planet, both in terms of drag as well as lift. This cloud is created during the passage of the spacecraft by the atmosphere of the planet, which is the responsible by the explosion of the spacecraft. The dynamical system is compos by the planet, the Sun, and the spacecraft, which explodes and becomes a cloud of debris. The planet and the Sun are in circular planar orbits. The equations of motion are the ones of the circular planar restricted three-body problem with the addition of the forces given by the atmospheric: drag and lift. The planet Jupiter is used for the numerical simulations. The initial conditions of the spacecraft and the debris are specified at the periapsis, which is the point where the explosion occurs. The equations of motion are numerically integrated forward in time for each particle, until a point where the particle is at a distance that can be considered far enough from the planet and it is possible to disregard the effects of the planet and consider the Sun-particle as a two-body system. Then we compute the velocity, energy and angular momentum after the passage by the planet, for each particle, based in the two-body celestial mechanics. From those results, the eccentricity and the semi-major axis of each particle can be obtained. Then, the orbit of the spacecraft is integrated backwards in time, as a single body. The difference from the usual close approaches technique is the presence of the atmosphere of the planet, which generates a drag and a lift forces in the spacecraft, which causes the explosion and modifies the trajectories of the debris generated by the explosion. The primary objective of the present paper is to map the modifications of the orbits of the debris that compose the cloud due to the close approach with the planet. Emphasis is given to map the orbital parameters of the debris after the close approach with the planet. Then, the effects are compared with the same maneuvers performed without the inclusion of the atmosphere. This type of research is useful, because it helps to obtain the size and density of the cloud of debris after the passage, as a function of time. That information has impact on the evaluations of the risks that spacecrafts suffer when passing by shorter distances from this cloud.

Satellite Ephemeris Correction via Remote Site Observation for Star Tracker Navigation Performance Improvement

DTIC Science & Technology

2016-03-01

squared RMS root mean squared GCRF Geocentric Celestial Reference Frame xi List of Figures Figure Page 1 Geometry of single observation...RA and DEC in the celestial sphere. The Geocentric Celestial Reference Frame (GCRF) is the standard geocentric frame that measures the RA east in the...Figure 2. Right ascension (α) and declination (δ) in the celestial sphere[6] 7 made between geocentric and topocentric angles. Geocentric is referred to

A recursive approach to the equations of motion for the maneuvering and control of flexible multi-body systems

NASA Technical Reports Server (NTRS)

Kwak, Moon K.; Meirovitch, Leonard

1991-01-01

Interest lies in a mathematical formulation capable of accommodating the problem of maneuvering a space structure consisting of a chain of articulated flexible substructures. Simultaneously, any perturbations from the 'rigid body' maneuvering and any elastic vibration must be suppressed. The equations of motion for flexible bodies undergoing rigid body motions and elastic vibrations can be obtained conveniently by means of Lagrange's equations in terms of quasi-coordinates. The advantage of this approach is that it yields equations in terms of body axes, which are the same axes that are used to express the control forces and torques. The equations of motion are nonlinear hybrid differential quations. The partial differential equations can be discretized (in space) by means of the finite element method or the classical Rayleigh-Ritz method. The result is a set of nonlinear ordinary differential equations of high order. The nonlinearity can be traced to the rigid body motions and the high order to the elastic vibration. Elastic motions tend to be small when compared with rigid body motions.

Application of the integral manifold method to the analysis of the spatial motion of a rigid body fixed to a cable

NASA Astrophysics Data System (ADS)

Zabolotnov, Yu. M.

2016-07-01

We analyze the spatial motion of a rigid body fixed to a cable about its center of mass when the orbital cable system is unrolling. The analysis is based on the integral manifold method, which permits separating the rigid body motion into the slow and fast components. The motion of the rigid body is studied in the case of slow variations in the cable tension force and under the action of various disturbances.We estimate the influence of the static and dynamic asymmetry of the rigid body on its spatial motion about the cable fixation point. An example of the analysis of the rigid body motion when the orbital cable system is unrolling is given for a special program of variations in the cable tension force. The conditions of applicability of the integral manifold method are analyzed.

Astrology: Science, Art or Prophesy

NASA Astrophysics Data System (ADS)

Yeghiazaryan, Anahit

2016-12-01

The subject in question is the link between humanity's two earliest disciplines - astronomy and astrology. Is it realistic to assume that the arrangement of celestial bodies, planets and stars can provide an opportunity to unequivocally predetermine the faith of the flora and fauna, of single individuals or entire nations living on planet Earth of the Solar System in the entirety of the Universe? Is it possible to ascertain whether astrology is science, art or prophesy?

The International Ultraviolet Explorer: Case study in spacecraft design

NASA Technical Reports Server (NTRS)

Freeman, H. R.; Longanecker, G. W.

1979-01-01

The International Ultraviolet Explorer (IUE) is a geosynchronous scientific satellite that was conceived as an international space observatory capable of measuring UV spectra of faint celestial bodies. Simple operational procedures allow the astronomers to joystick the spaceborne telescope about the sky, using familiar ground-based observatory techniques. The present paper deals with the IUE project objectives, the technical problems, constraints, trade-offs, and the problem solving techniques used in the IUE program.

Astrology: Science, Art or Prophesy

NASA Astrophysics Data System (ADS)

Yeghiazaryan, A. A.

2015-07-01

The subject in question is the link between humanity's two earliest disciplines - Astronomy and Astrology. Is it realistic to assume that the arrangement of celestial bodies, planets and stars can provide an opportunity to unequivocally predetermine the faith of the flora and fauna, of single individuals or entire nations living on planet Earth of the Solar System in the entirety of the Universe? Is it possible to ascertain whether astrology is science, art or prophesy?

3DView: Space physics data visualizer

NASA Astrophysics Data System (ADS)

Génot, V.; Beigbeder, L.; Popescu, D.; Dufourg, N.; Gangloff, M.; Bouchemit, M.; Caussarieu, S.; Toniutti, J.-P.; Durand, J.; Modolo, R.; André, N.; Cecconi, B.; Jacquey, C.; Pitout, F.; Rouillard, A.; Pinto, R.; Erard, S.; Jourdane, N.; Leclercq, L.; Hess, S.; Khodachenko, M.; Al-Ubaidi, T.; Scherf, M.; Budnik, E.

2018-04-01

3DView creates visualizations of space physics data in their original 3D context. Time series, vectors, dynamic spectra, celestial body maps, magnetic field or flow lines, and 2D cuts in simulation cubes are among the variety of data representation enabled by 3DView. It offers direct connections to several large databases and uses VO standards; it also allows the user to upload data. 3DView's versatility covers a wide range of space physics contexts.

Breakthrough in orbit determination of a binary. - In expectation of astrometric observations with high precision such as VERA and JASMINE -

NASA Astrophysics Data System (ADS)

Asada, Hideki

2006-11-01

There exists a very classical inverse problem regarding orbit determination of a binary system: "when an orbital plane of two bodies is inclined with respect to the line of sight, observables are their positions projected onto a celestial sphere. How do we determine the orbital elements from observations?" A "complete exact solution" has been found. It is reviewed with some related topics.

Fuel-efficient feedback control of orbital motion around irregular-shaped asteroids

NASA Astrophysics Data System (ADS)

Winkler, Timothy Michael

Unmanned probes are the primary technologies used when exploring celestial bodies in our solar system. As these deep space exploration missions are becoming more and more complex, there is a need for advanced autonomous operation capabilities in order to meet mission objectives. These autonomous capabilities are required as ground-based guidance and navigation commands will not be able to be issued in real time due to the large distance from the Earth. For long-duration asteroid exploration missions, this also entails how to keep the spacecraft around or on the body in order for the mission to be successfully completed. Unlike with larger bodies such as planets, though, the dynamical environment around these smaller bodies can be difficult to characterize. The weak gravitational fields are not uniform due to irregular shapes and non-homogeneous mass distribution, especially when orbiting in close-proximity to the body. On top of that, small perturbation forces such as solar radiation pressure can be strong enough to destabilize an orbit around an asteroid. The best solution for keeping a spacecraft in orbit about a small body is to implement some form of control technique. With conventional propulsion thrusters, active control algorithms tend to have a higher than acceptable propellant requirements for long-duration asteroid exploration missions, which has led to much research being devoted to finding open-loop solutions to long-term stable orbits about small bodies. These solutions can prove to be highly sensitive to the orbit's initial conditions, making them potentially unreliable in the presence of orbit injection errors. This research investigates a fuel-efficient, active control scheme to safely control a spacecraft's orbit in close-proximity to an asteroid. First, three different gravitational models capable of simulating the non-homogeneous gravity fields of asteroids are presented: the polyhedron gravity shape model, a spherical harmonics expansion, and an inertia dyadic gravity model. Then a simple feedback controller augmented by a disturbance-accommodating filter is employed to ensure orbital stability. Using these models and controller, several orbiting cases as well as body-frame hovering are investigated to test the viability and fuel-efficiency of the proposed control system. The ultimate goal is to design an active orbit control system with minimum DeltaV expenditure.

An Overview of the Exploration History of Europa

NASA Astrophysics Data System (ADS)

Alexander, C. J.; Consolmagno, G.; Greeley, R.; Morrison, D.

2007-12-01

Twenty-four years ago, a Nature paper announced the results of study of the Voyager images of the Jovian moon Europa, in which linear fracture-like markings were projected to be evidence of liquid water and active resurfacing [Nature 301, 225 - 226 (20 January 1983)]. This paper was a post-Voyager study that pre-dated the Galileo findings by two decades. Years of modeling had gone into the effort to understand the potential thermal history of the icy moons of Jupiter. Much of the theoretical work concluded that the bodies would have been frozen solid for billions of years, but there was enough work to suggest further in situ investigation was warranted. Behind the scenes was a concerted effort to make the Galilean satellites the focus of unmanned exploration for NASA's planetary science program. The historic significance of this journey of exploration, the manner in which it unfolded, is of relevance to a whole new generation of investigators. In this talk we will present highlights of the entire period of discovery, from the commensurate orbital motions first observed by Galileo himself [1609], that would prove critical to understanding the evolution of Europa; the theoretical work on motions of the celestial bodies by Laplace [1805] that laid the ground work for understanding the resonances; Jeans [1925] speculations about the existence of the atmospheres of the Galilean satellites in his Theory of Gases; to the ground-breaking discovery by Kuiper of the spectral signature of ice on Europa ; the work by Urey [1952] making the cosmochemical arguments about the significance of water ice in the outer solar system; efforts to understand, from photometry and spectrometry, whether surface impurities were endogenic or exogenic in origin; and the work of Johnson and colleagues laying the groundwork for the understanding of the significance of sputtering in the solar system [Johnson, et al., 1982]. We will present highlights of the exploration of the Jupiter system with spacecraft in the 1970's and '80's; and close with the discoveries of the Galileo mission as they unfolded.

A Snapshot-Based Mechanism for Celestial Orientation.

PubMed

El Jundi, Basil; Foster, James J; Khaldy, Lana; Byrne, Marcus J; Dacke, Marie; Baird, Emily

2016-06-06

In order to protect their food from competitors, ball-rolling dung beetles detach a piece of dung from a pile, shape it into a ball, and roll it away along a straight path [1]. They appear to rely exclusively on celestial compass cues to maintain their bearing [2-8], but the mechanism that enables them to use these cues for orientation remains unknown. Here, we describe the orientation strategy that allows dung beetles to use celestial cues in a dynamic fashion. We tested the underlying orientation mechanism by presenting beetles with a combination of simulated celestial cues (sun, polarized light, and spectral cues). We show that these animals do not rely on an innate prediction of the natural geographical relationship between celestial cues, as other navigating insects seem to [9, 10]. Instead, they appear to form an internal representation of the prevailing celestial scene, a "celestial snapshot," even if that scene represents a physical impossibility for the real sky. We also find that the beetles are able to maintain their bearing with respect to the presented cues only if the cues are visible when the snapshot is taken. This happens during the "dance," a behavior in which the beetle climbs on top of its ball and rotates about its vertical axis [11]. This strategy for reading celestial signals is a simple but efficient mechanism for straight-line orientation. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Advanced Part of a Treatise on the Dynamics of a System of Rigid Bodies

NASA Astrophysics Data System (ADS)

Routh, Edward John

2013-03-01

Preface; 1. Moving axes and relative motion; 2. Oscillations about equilibrium; 3. Oscillations about a state of motion; 4. Motion of a body under no forces; 5. Motion of a body under any forces; 6. Nature of the motion given by linear equations and the conditions of stability; 7. Free and forced oscillations; 8. Determination of the constants of integration in terms of the initial conditions; 9. Calculus of finite differences; 10. Calculus of variations; 11. Precession and nutation; 12. Motion of the moon about its centre; 13. Motion of a string or chain; 14. Motion of a membrane; Notes.

Some Aspects of Artificial Bodies Stabilization and Orientation

NASA Astrophysics Data System (ADS)

Samardzija, B.; Segan, S.

2012-12-01

To increase energy resources, and thus the overall possibility of modern cosmic aircrafts, power supply was expanded by adding the (moving) wing area and antenna with complex orientation and design. It is clear that all of this, when there is a need to conduct a very accurate account of orbital elements of satellites, is a nightmare for the experts and scientists. In this paper we will give special attention to the system of stabilization and orientation of satellites, as well as to the importance of gyroscopic effects and the navigation systems of the artificial celestial bodies. Development of modified practical solutions based on knowledge and experience with gyroscopic effects is immeasurable.

OFO experimental techniques and preliminary conclusions - Is artificial gravity needed during prolonged weightlessness.

NASA Technical Reports Server (NTRS)

Gualtierotti, T.; Bracchi, F.

1972-01-01

The technique of single unit recording from body systems generating electrical pulses coherent with their basic function (CNS, muscles, sense organs) has been proved feasible during the OFO A orbital flight, an automatic physiological experiment. The results of recording 155 hours of orbital flight of pulses from the nerve fibres of four vestibular gravity sensors in two bull frogs indicate that the vestibular organ adjusts to zero g. As all the other biological changes observed during orbit are due to lack of exercise, it is concluded that artificial gravity might not be necessary during prolonged space missions or on low gravity celestial bodies.

Analysis of Sel-Gravitating Planetary Satellites in the Solar System

NASA Astrophysics Data System (ADS)

Yasenev, S. O.

As of today there have been more than 180 planetary satellites discovered in the Solar system, and the number of outer moons found continues to grow. Most of those natural satellites have insufficient mass and are able to retain their shape only due to the strength of the electromagnetic force. The purpose of this paper is to analyze the moons' physical properties. The analysis of planetary satellites as self-gravitating bodies, i.e. celestial bodies which rely on the weight of their own mass and resulting gravitational force to maintain their shape and tend to bring it closer to the hydrostatic equilibrium, was performed.

Planetary protection - some legal questions

NASA Astrophysics Data System (ADS)

Fasan, E.

2004-01-01

When we legally investigate the topic of Planetary Protection, we have to realise that there are primarily two very distinct parts of our juridical work: We have to study lexlata, theexistingapplicableLaw, especially Space Law, and also lexferenda, whatshouldbethe law . With this in mind, we have to deliberate the legal meaning of the notions "Planetary", and "Protection". About " Planetary": Our own Earth is our most important planet. At present only here do exist human beings, who are sensu strictu the only legal subjects. We make the law, we have to apply it, and we are to be protected as well as bound by it. But what is further meant by "Planetary"? Is it planets in an astronomical sense only, the nine planets which revolve around our fixed star, namely the sun, or is it also satellites, moving around most of these planets, as our own Moon circles Earth. "The Moon and other Celestial Bodies (C.B.)" are subject to Space Law, especially to International Treaties, Agreements, Resolutions of the UN, etc. I propose that they and not only the planets in an strictly astronomical sense are to be protected. But I do not think that the said notion also comprises asteroids, comets, meteorites, etc. although they too belong to our solar system. Our investigation comes to the result that such bodies have a different (lesser) legal quality. Also we have to ask Protectionfrom what ? From: Natural bodies - Meteorites, NEO Asteroids, Comets which could hit Earth or C.B.Artificial Objects: Space Debris threatening especially Earth and near Earth orbits.Terrestrial Life - no infection of other celestial bodies. Alien life forms which could bring about "harmful contamination" of Earth and the life, above all human life, there, etc. Here, astrobiological questions have to be discussed. Special realms on C.B. which should be protected from electronic "noise" such as craters SAHA or Deadalus on the Moon, also taking into account the "Common Heritage" Principle. Then, we have to examine: Protectionwhere, of whom andofwhat: On Earth: Humans, and nature, namely other life forms, air, water and soil, but also all man made things. On Other celestial bodies: Crew of manned Space Missions, Stations on C.B., possible alien life forms, or remnants of such, water, other environment on C.B. - even if completely barren? Protection of C.B. from becoming "an area of international conflict". Finally, we have to discuss overriding interests, such as deflection of Asteroids which threaten to hit Earth, then the legally permitted "Use" of C.B., also mining versus protection, then, too high costs of absolutely sterile Spacecraft, etc. With this, we have de lege ferenda to create an order of values of protection, whereby the protection of the higher category has priority over the lesser ones.

Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

NASA Astrophysics Data System (ADS)

Könik, Arda; Connolly, Caitlin M.; Johnson, Karen L.; Dasari, Paul; Segars, Paul W.; Pretorius, P. H.; Lindsay, Clifford; Dey, Joyoni; King, Michael A.

2014-07-01

The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory and body motion phantoms with a varying extent and character for each individual. In addition to these phantoms, we recorded the position of markers placed on the chest of the volunteers for the body motion studies, which could be used as external motion measurement. Using these phantoms and external motion data, investigators will be able to test their motion correction approaches for realistic motion obtained from different individuals. The non-uniform rational B-spline data and the parameter files for these phantoms are freely available for downloading and can be used with the XCAT license.

Study of the long time-scale variability of cosmic rays with the ARGO-YBJ experiment

NASA Astrophysics Data System (ADS)

Cappa, Alba; James, Irina; Salvini, Paola

The long term modulation of the cosmic ray intensity includes both Sun and celestial anisotropies. The solar activity is due to high energy flares producing a decrease (known as Forbush Decrease, FD) in the cosmic ray intensity, with a time scale of the order of a few days, often accompained by a Ground Level Enhancement, due to direct Sun emission during the solar flare. The celestial anisotropies are due to the Earth motion in the cosmic rays reference system (solar anisotropy: Compton-Getting effect) and to the solar system location inside the Galaxy (sidereal anisotropies). These anisotropies are studied in ground-base experiments by means of EAS arrays, and the high energy solar emission is mainly studied from ground by neutron monitors. In the ARGO-YBJ experiment these phenomena are investigated by means of the "scaler mode" technique: the detector counting rates of four low multiplicity channels from singles to four-fold coincidences are recorded in a fixed time window of 0.5 s. The signal corresponds to a significant enhancement of the observed counting rate, after correcting the data for enviromental and instrumental parameters. In this paper we present the sensitivity of the ARGO-YBJ detector and the first results for both solar physics and cosmic ray anisotropy studies.

Smoothing and Predicting Celestial Pole Offsets using a Kalman Filter and Smoother

NASA Astrophysics Data System (ADS)

Nastula, J.; Chin, T. M.; Gross, R. S.; Winska, M.; Winska, J.

2017-12-01

Since the early days of interplanetary spaceflight, accounting for changes in the Earth's rotation is recognized to be critical for accurate navigation. In the 1960s, tracking anomalies during the Ranger VII and VIII lunar missions were traced to errors in the Earth orientation parameters. As a result, Earth orientation calibration methods were improved to support the Mariner IV and V planetary missions. Today, accurate Earth orientation parameters are used to track and navigate every interplanetary spaceflight mission. The interplanetary spacecraft tracking and navigation teams at JPL require the UT1 and polar motion parameters, and these Earth orientation parameters are estimated by the use of a Kalman filter to combine past measurements of these parameters and predict their future evolution. A model was then used to provide the nutation/precession components of the Earth's orientation separately. As a result, variations caused by the free core nutation were not taken into account. But for the highest accuracy, these variations must be considered. So JPL recently developed an approach based upon the use of a Kalman filter and smoother to provide smoothed and predicted celestial pole offsets (CPOs) to the interplanetary spacecraft tracking and navigation teams. The approach used at JPL to do this and an evaluation of the accuracy of the predicted CPOs will be given here.

How Ants Use Vision When Homing Backward.

PubMed

Schwarz, Sebastian; Mangan, Michael; Zeil, Jochen; Webb, Barbara; Wystrach, Antoine

2017-02-06

Ants can navigate over long distances between their nest and food sites using visual cues [1, 2]. Recent studies show that this capacity is undiminished when walking backward while dragging a heavy food item [3-5]. This challenges the idea that ants use egocentric visual memories of the scene for guidance [1, 2, 6]. Can ants use their visual memories of the terrestrial cues when going backward? Our results suggest that ants do not adjust their direction of travel based on the perceived scene while going backward. Instead, they maintain a straight direction using their celestial compass. This direction can be dictated by their path integrator [5] but can also be set using terrestrial visual cues after a forward peek. If the food item is too heavy to enable body rotations, ants moving backward drop their food on occasion, rotate and walk a few steps forward, return to the food, and drag it backward in a now-corrected direction defined by terrestrial cues. Furthermore, we show that ants can maintain their direction of travel independently of their body orientation. It thus appears that egocentric retinal alignment is required for visual scene recognition, but ants can translate this acquired directional information into a holonomic frame of reference, which enables them to decouple their travel direction from their body orientation and hence navigate backward. This reveals substantial flexibility and communication between different types of navigational information: from terrestrial to celestial cues and from egocentric to holonomic directional memories. VIDEO ABSTRACT. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Construction of a Radio-Telescope Prototype in the 12 GHz Band

NASA Astrophysics Data System (ADS)

Ordóñez, J.; Quijano, A.; Luna, A.

2017-07-01

Radio astronomy is important in the branch of the Astronomy that studies the celestial bodies through their emissions in the domain of the radio waves, to obtain information of these bodies, astronomers must design new types of telescopes that can capture radiation at different wavelengths, including radio telescopes. This paper presents the construction of a prototype of an educational radio telescope, which is made using materials that are easily accessible and inexpensive. The construction of a radio telescope, will allow to carry out research in the field of radio astronomy, since at present it has not been possible to penetrate this branch due to the lack of an adequate equipment in the University of Nariño. The issues that are addressed in the construction of this instrument, its use and the analysis of the data, are very varied and with a high content of multidiciplinariety, gathering basic topics in areas such as astrophysics, physics, electronics, computing, mechanics, which are necessary for Concrete the efficient use of this instrument. For the development of the project, it counts with the advice of the director and researcher of the astronomical observatory of the University of Nariño MSc. Alberto Quijano Vodniza and Dr. Abraham Luna Castellanos of the National Institute of Astrophysics, Optics and Electronics INAOE. In addition to the construction of radiotelescope the final phase consists of the storage and analysis of data obtained with the observation of some celestial bodies that comply with The range in the 12 GHz band for study.

The Distortion of a Body's Visible Shape at Relativistic Speeds

ERIC Educational Resources Information Center

Arkadiy, Leonov

2009-01-01

The problem of obtaining the apparent equation of motion and shape of a moving body from its arbitrary given equation of motion in special relativity is considered. Also the inverse problem of obtaining the body's equation of motion from a known equation of motion of its image is discussed. Some examples of this problem solution are considered. As…

Asteroids - the modern challenge of celestial dynamics

NASA Astrophysics Data System (ADS)

Dikova, Smiliana

2002-11-01

Among the most powerful statements in Science are those that mark absolute limits to knowledge. For example, Relativity and Quantum Theory touched the limits of speed and accuracy. Deterministic Chaos - the new scientific paradigma of our days, also falls in this class theories. Chaos means complexity in space and unpredictability in time. It shows the limit of our basic counting system and leads to a limited predictability of the long time dynamical evolution. Perhaps for that reason, in 1986 Sir James Lighthill remarked for all physicists: "We collectively wish to apologize for having misled the general educated public by spreading ideas about the determinism of systems satisfying Newton's laws of motion that, after 1960, were proved incorrect." Our main thesis is that Asteroid Dynamics is the arena where the drama Chaos versus predictability is initiated and developed. The aim of the present research is to show the way in which Deterministic Chaos restricts the long term dynamical predictability of asteroid motions.

Solar and lunar calendars of the mountain sanctuary Kokino

NASA Astrophysics Data System (ADS)

Kuzmanovska, Olgica; Stankovski, Jovica; Apostolovska, Gordana

2016-03-01

The mountain sanctuary Kokino is located in the northeast part of Macedonia, on the summit of a hill of volcanic origin. The archeological research that has been performed for more than a decade confirmed its use as a large extra-urban religious site during the whole period of the Bronze Age. Additional astronomical analyses showed that it has the characteristics of a megalithic observatory, with some of its religious cults related with the motion of the sun, moon and some of the brightest stars. For that purpose the periodic motion of these celestial objects was observed and their position on specific calendar dates marked by stone notches cut in the surrounding rocks. In this paper, we present the results of the astronomical investigation of a group of stone markers aligned toward the specific positions of the full moon and analyze their purpose in creating a simple solar and lunar calendar which was used in planning the everyday life of the Bronze Age people in the region.

Error Modeling of Multibaseline Optical Truss: Part 1: Modeling of System Level Performance

NASA Technical Reports Server (NTRS)

Milman, Mark H.; Korechoff, R. E.; Zhang, L. D.

2004-01-01

Global astrometry is the measurement of stellar positions and motions. These are typically characterized by five parameters, including two position parameters, two proper motion parameters, and parallax. The Space Interferometry Mission (SIM) will derive these parameters for a grid of approximately 1300 stars covering the celestial sphere to an accuracy of approximately 4uas, representing a two orders of magnitude improvement over the most precise current star catalogues. Narrow angle astrometry will be performed to a 1uas accuracy. A wealth of scientific information will be obtained from these accurate measurements encompassing many aspects of both galactic (and extragalactic science. SIM will be subject to a number of instrument errors that can potentially degrade performance. Many of these errors are systematic in that they are relatively static and repeatable with respect to the time frame and direction of the observation. This paper and its companion define the modeling of the, contributing factors to these errors and the analysis of how they impact SIM's ability to perform astrometric science.

Solar system to scale

NASA Astrophysics Data System (ADS)

Gerwig López, Susanne

2016-04-01

One of the most important successes in astronomical observations has been to determine the limit of the Solar System. It is said that the first man able to measure the distance Earth-Sun with only a very slight mistake, in the second century BC, was the wise Greek man Aristarco de Samos. Thanks to Newtońs law of universal gravitation, it was possible to measure, with a little margin of error, the distances between the Sun and the planets. Twelve-year old students are very interested in everything related to the universe. However, it seems too difficult to imagine and understand the real distances among the different celestial bodies. To learn the differences among the inner and outer planets and how far away the outer ones are, I have considered to make my pupils work on the sizes and the distances in our solar system constructing it to scale. The purpose is to reproduce our solar system to scale on a cardboard. The procedure is very easy and simple. Students of first year of ESO (12 year-old) receive the instructions in a sheet of paper (things they need: a black cardboard, a pair of scissors, colored pencils, a ruler, adhesive tape, glue, the photocopies of the planets and satellites, the measurements they have to use). In another photocopy they get the pictures of the edge of the sun, the planets, dwarf planets and some satellites, which they have to color, cut and stick on the cardboard. This activity is planned for both Spanish and bilingual learning students as a science project. Depending on the group, they will receive these instructions in Spanish or in English. When the time is over, the students bring their works on their cardboard to the class. They obtain a final mark: passing, good or excellent, depending on the accuracy of the measurements, the position of all the celestial bodies, the asteroids belts, personal contributions, etc. If any of the students has not followed the instructions they get the chance to remake it again properly, in order not to obtain the "failing" mark. When the teacher notices that some mistakes can be easily improved, students can do it. If the students have forgotten to write the names of the celestial bodies, they should add them. Finally, their works will be exposed in the classroom.

The Estimation of a Rigid Body Motion in the Presence of Noise.

DTIC Science & Technology

1987-07-31

Rigid Body Motion in the Presence of Noise 12. PERSONAL AUTHOR(S) 1S. AYOFDREPRTy 13b.e ad COVRE C4. 10AOUTE OF FUNPING NUBERSlAE...8217, .,_, .,,.. .\\ ..: ., : ’ *-: ,:,.,,. .’ 4 /. .’.’ ’, ’ ,. 9) 7 TRACT The problem of estimating a rigid body motion from two noisy images of an...SI ... ... Cs . I ,-’ ’".’ 1 -, ED 1, D:;.;i,1q L HARVARD UNIVERSITY DzPAILTMNT OP STATIMCS THE ESTIMATION OF A RIGID BODY MOTION IN THE

Martian and Asteroid Dusts as Toxicological Risks for Human Exploration Missions

NASA Technical Reports Server (NTRS)

James, John T.

2012-01-01

As the lunar dust toxicity project winds down, our attention is drawn to the potential toxicity of dust present at the surface of more distant celestial objects. Lunar dust has proven to be surprisingly toxic to the respiratory systems of test animals, so one might expect dust from other celestial bodies to hold toxicological surprises for us. At this point all one can do is consider what should be known about these dusts to characterize their toxicity, and then ask to what extent that information is known. In an ideal world it might be possible to suggest an exposure standard based on the known properties of a celestial dust without direct testing of the dust in laboratory animals. Factors known to affect the toxicity of mineral dusts under some conditions include the following: particle size distribution, particle shape/porosity, mineralogical properties (crystalline vs. amorphous), chemical properties and composition, and surface reactivity. Data from a recent Japanese mission to the S-type asteroid Itokawa revealed some surprises about the dust found there, given that there is only a very week gravitational field to hold the dust on the surface. On Mars the reddish-brown dust is widely distributed by global dust storms and by local clusters of dust devils. Past surface probes have revealed some of the properties of dust found there. Contemporary data from Curiosity and other surface probes will be weighed against the data needed to set a defensible safe exposure limit. Gaps will emerge.

Insect Responses to Linearly Polarized Reflections: Orphan Behaviors Without Neural Circuits

PubMed Central

Heinloth, Tanja; Uhlhorn, Juliane; Wernet, Mathias F.

2018-01-01

The e-vector orientation of linearly polarized light represents an important visual stimulus for many insects. Especially the detection of polarized skylight by many navigating insect species is known to improve their orientation skills. While great progress has been made towards describing both the anatomy and function of neural circuit elements mediating behaviors related to navigation, relatively little is known about how insects perceive non-celestial polarized light stimuli, like reflections off water, leaves, or shiny body surfaces. Work on different species suggests that these behaviors are not mediated by the “Dorsal Rim Area” (DRA), a specialized region in the dorsal periphery of the adult compound eye, where ommatidia contain highly polarization-sensitive photoreceptor cells whose receptive fields point towards the sky. So far, only few cases of polarization-sensitive photoreceptors have been described in the ventral periphery of the insect retina. Furthermore, both the structure and function of those neural circuits connecting to these photoreceptor inputs remain largely uncharacterized. Here we review the known data on non-celestial polarization vision from different insect species (dragonflies, butterflies, beetles, bugs and flies) and present three well-characterized examples for functionally specialized non-DRA detectors from different insects that seem perfectly suited for mediating such behaviors. Finally, using recent advances from circuit dissection in Drosophila melanogaster, we discuss what types of potential candidate neurons could be involved in forming the underlying neural circuitry mediating non-celestial polarization vision. PMID:29615868

Research on the error model of airborne celestial/inertial integrated navigation system

NASA Astrophysics Data System (ADS)

Zheng, Xiaoqiang; Deng, Xiaoguo; Yang, Xiaoxu; Dong, Qiang

2015-02-01

Celestial navigation subsystem of airborne celestial/inertial integrated navigation system periodically correct the positioning error and heading drift of the inertial navigation system, by which the inertial navigation system can greatly improve the accuracy of long-endurance navigation. Thus the navigation accuracy of airborne celestial navigation subsystem directly decides the accuracy of the integrated navigation system if it works for long time. By building the mathematical model of the airborne celestial navigation system based on the inertial navigation system, using the method of linear coordinate transformation, we establish the error transfer equation for the positioning algorithm of airborne celestial system. Based on these we built the positioning error model of the celestial navigation. And then, based on the positioning error model we analyze and simulate the positioning error which are caused by the error of the star tracking platform with the MATLAB software. Finally, the positioning error model is verified by the information of the star obtained from the optical measurement device in range and the device whose location are known. The analysis and simulation results show that the level accuracy and north accuracy of tracking platform are important factors that limit airborne celestial navigation systems to improve the positioning accuracy, and the positioning error have an approximate linear relationship with the level error and north error of tracking platform. The error of the verification results are in 1000m, which shows that the model is correct.

Precise Image-Based Motion Estimation for Autonomous Small Body Exploration

NASA Technical Reports Server (NTRS)

Johnson, Andrew E.; Matthies, Larry H.

1998-01-01

Space science and solar system exploration are driving NASA to develop an array of small body missions ranging in scope from near body flybys to complete sample return. This paper presents an algorithm for onboard motion estimation that will enable the precision guidance necessary for autonomous small body landing. Our techniques are based on automatic feature tracking between a pair of descent camera images followed by two frame motion estimation and scale recovery using laser altimetry data. The output of our algorithm is an estimate of rigid motion (attitude and position) and motion covariance between frames. This motion estimate can be passed directly to the spacecraft guidance and control system to enable rapid execution of safe and precise trajectories.

On-Board Perception System For Planetary Aerobot Balloon Navigation

NASA Technical Reports Server (NTRS)

Balaram, J.; Scheid, Robert E.; T. Salomon, Phil

1996-01-01

NASA's Jet Propulsion Laboratory is implementing the Planetary Aerobot Testbed to develop the technology needed to operate a robotic balloon aero-vehicle (Aerobot). This earth-based system would be the precursor for aerobots designed to explore Venus, Mars, Titan and other gaseous planetary bodies. The on-board perception system allows the aerobot to localize itself and navigate on a planet using information derived from a variety of celestial, inertial, ground-imaging, ranging, and radiometric sensors.

Software and hardware complex for observation of star occultations by asteroids

NASA Astrophysics Data System (ADS)

Karbovsky, V.; Kleshchonok, V.; Buromsky, M.

2017-12-01

The preparation to the program for observation of star occultations by asteroids on the AZT-2 telescope was started in 2016. A new method for registration of occultation with a CCD camera in the synchronous transfer mode was proposed and developed. The special program was written to control the CCD camera and record images during such observations. The speed of image transfer can vary within wide limits, which makes it possible to carry out observations in a wide range of stellar magnitudes. The telescope AZT-2 is used, which has the largest mirror diameter in Kiev (D = 0.7 m. F = 10.5 m). A 3-fold optical reducer was produced, which providing a field of view with a CCD camera Apogee Alta U47 10 arcminutes and the equivalent focal length of the telescope 3.2 meters. The results of test observations are presented. The program is implemented jointly by the Main Astronomical Observatory of the National Academy of Sciences of Ukraine and the Astronomical Observatory of the Taras Shevchenko National University of Kyiv. Regular observations of star occultation by asteroids are planned with the help of this complex. % Z https://occultations.org Kleshchonok,V.V.,Buromsky,M. I. 2005, Kinematics and Physics of Celestial Bodies, 21, 5, 405 Kleshchonok, V.V., Buromskii, N. I., Khat’ko,I.V.2008, Kinematics and Physics of Celestial Bodies, 24, 2, 114

Robust polygon recognition method with similarity invariants applied to star identification

NASA Astrophysics Data System (ADS)

Hernández, E. Antonio; Alonso, Miguel A.; Chávez, Edgar; Covarrubias, David H.; Conte, Roberto

2017-02-01

In the star identification process the goal is to recognize a star by using the celestial bodies in its vicinity as context. An additional requirement is to avoid having to perform an exhaustive scan of the star database. In this paper we present a novel approach to star identification using similarity invariants. More specifically, the proposed algorithm defines a polygon for each star, using the neighboring celestial bodies in the field of view as vertices. The mapping is insensitive to similarity transformation; that is, the image of the polygon under the transformation is not affected by rotation, scaling or translations. Each polygon is associated with an essentially unique complex number. We perform an exhaustive experimental validation of the proposed algorithm using synthetic data generated from the star catalog with uniformly-distributed positional noise introduced to each star. The star identification method that we present is proven to be robust, achieving a recognition rate of 99.68% when noise levels of up to ± 424 μ radians are introduced to the location of the stars. In our tests the proposed algorithm proves that if a polygon match is found, it always corresponds to the star under analysis; no mismatches are found. In its present form our method cannot identify polygons in cases where there exist missing or false stars in the analyzed images, in those situations it only indicates that no match was found.

Kilohoku - Ho‘okele Wa‘a: Hawaiian Navigational Astronomy

NASA Astrophysics Data System (ADS)

Dye, Ahia; Ha'o, Celeste; Slater, Timothy F.; Slater, Stephanie

2015-01-01

Over thousands of years of Pacific Basin settlement, Polynesians developed a complex, scientific understanding of the cosmos, including a generative view of the celestial sphere. Memorizing the location and spatial relationships of hundreds of stars, across changing latitudes, this astronomy was one of the four scientific knowledge bases Polynesians used to navigate thousands of miles, across open water, without instrumentation. After Western colonization, this large body of knowledge was nearly lost to Hawaiians. Since the Hawaiian Renaissance, much of this knowledge has been reconstructed, and is again in use in open oceanic navigation. While some of this knowledge has been shared with the broader public, much of what we know has been unavailable to those beyond the family of navigators. This paper represents an attempt to begin sharing this catalog of knowledge with the outside world, with the hopes that the larger community will appreciate the complexity of astronomical knowledge possessed by navigators, and that the international body of astronomy historians will help insure that this knowledge will not be lost again. This paper will present, Na ´Ohanahōkū, the Hawaiian star families that divide the celestial sphere into four wedges, running from the circumpolar north, beyond the horizon to the south. Na Hoku Huihui, or Hawaiian constellations will be discussed, in addition to a brief introduction to the setting and rising pairs that are used to determine direction and latitude.

The Theme of Celestial Bodies in Armenian Lullabies

NASA Astrophysics Data System (ADS)

Hakobyan, Ani

2016-12-01

Folk art is representing the type and the mentality of the nation. People's perceptions and understanding of life, the universe and the world around them are reflected in it. In folk songs coming from the times before Christianity and preserved until now there are many cosmic bodies commemorations and many attempts to consider man as heliocentric and important phenomenon. In this case, we focus on the presence of the sun, the moon and stars in one of the most interesting genres of Armenian folk music - lullabies. This article is meant to represent the ancient Pythagorean theory of cosmic origins of music and coming back to the mentioned genre of the folk art it is also showing the imaging of cosmic bodies on recorded samples of Armenian lullabies of various areas and provinces.

Combining sky and earth: desert ants (Melophorus bagoti) show weighted integration of celestial and terrestrial cues.

PubMed

Legge, Eric L G; Wystrach, Antoine; Spetch, Marcia L; Cheng, Ken

2014-12-01

Insects typically use celestial sources of directional information for path integration, and terrestrial panoramic information for view-based navigation. Here we set celestial and terrestrial sources of directional information in conflict for homing desert ants (Melophorus bagoti). In the first experiment, ants learned to navigate out of a round experimental arena with a distinctive artificial panorama. On crucial tests, we rotated the arena to create a conflict between the artificial panorama and celestial information. In a second experiment, ants at a feeder in their natural visually-cluttered habitat were displaced prior to their homing journey so that the dictates of path integration (feeder to nest direction) based on a celestial compass conflicted with the dictates of view-based navigation (release point to nest direction) based on the natural terrestrial panorama. In both experiments, ants generally headed in a direction intermediate to the dictates of celestial and terrestrial information. In the second experiment, the ants put more weight on the terrestrial cues when they provided better directional information. We conclude that desert ants weight and integrate the dictates of celestial and terrestrial information in determining their initial heading, even when the two directional cues are highly discrepant. © 2014. Published by The Company of Biologists Ltd.

VizieR Online Data Catalog: Praesepe members masses (Khalaj+, 2013)

NASA Astrophysics Data System (ADS)

Khalaj, P.; Baumgardt, H.

2014-09-01

In this study, we combine data from the PPMXL catalogue (Roser et al., 2010AJ....139.2440R, Cat. I/317) with z magnitudes from SDSS DR9 (Ahn et al., 2012ApJS..203...21A, Cat. V/139). The PPMXL catalogue combines the USNO-B1.0 (Monet et al. 2003AJ....125..984M, Cat. I/284) and 2MASS catalogues (Skrutskie et al. 2006AJ....131.1163S, Cat. VII/233), yielding the largest collection of proper motions in the International Celestial Reference Frame to date (Roser et al., 2010AJ....139.2440R, Cat. I/317). Cat. J/A+A/531/A92). (1 data file).

ON THE CONNECTION OF THE APPARENT PROPER MOTION AND THE VLBI STRUCTURE OF COMPACT RADIO SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moor, A.; Frey, S.; Lambert, S. B.

2011-06-15

Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric very long baseline interferometry (VLBI) measurements. These changes can be as high as several hundred microarcseconds per year for certain objects. When imaged with VLBI at milliarcsecond (mas) angular resolution, these sources (radio-loud active galactic nuclei) typically show structures dominated by a compact, often unresolved 'core' and a one-sided 'jet'. The positional instability of compact radio sources is believed to be connected with changes in their brightness distribution structure. For themore » first time, we test this assumption in a statistical sense on a large sample rather than on only individual objects. We investigate a sample of 62 radio sources for which reliable long-term time series of astrometric positions as well as detailed 8 GHz VLBI brightness distribution models are available. We compare the characteristic direction of their extended jet structure and the direction of their apparent proper motion. We present our data and analysis method, and conclude that there is indeed a correlation between the two characteristic directions. However, there are cases where the {approx}1-10 mas scale VLBI jet directions are significantly misaligned with respect to the apparent proper motion direction.« less

Investigation of Liquid Sloshing in Spin-Stabilized Satellites.

DTIC Science & Technology

1993-01-31

deformation of the spinning structure in addition to the rigid body motion . A Lagrangian approach was used to develop the equations of motion which include...nonlinear relationships for the unknown rigid body motions and linear terms for the relatively small elastic deformations of the members. Appendix F...the rigid body motion of the test assembly. A pendulum analogy was used to model the sloshing liquid in that early program. Several numerical

Static and dynamic body image in bulimia nervosa: mental representation of body dimensions and biological motion patterns.

PubMed

Vocks, Silja; Legenbauer, Tanja; Rüddel, Heinz; Troje, Nikolaus F

2007-01-01

The aim of the present study was to find out whether in bulimia nervosa the perceptual component of a disturbed body image is restricted to the overestimation of one's own body dimensions (static body image) or can be extended to a misperception of one's own motion patterns (dynamic body image). Participants with bulimia nervosa (n = 30) and normal controls (n = 55) estimated their body dimensions by means of a photo distortion technique and their walking patterns using a biological motion distortion device. Not only did participants with bulimia nervosa overestimate their own body dimensions, but also they perceived their own motion patterns corresponding to a higher BMI than did controls. Static body image was correlated with shape/weight concerns and drive for thinness, whereas dynamic body image was associated with social insecurity and body image avoidance. In bulimia nervosa, body image disturbances can be extended to a dynamic component. (c) 2006 by Wiley Periodicals, Inc.

Coordinate measuring system

DOEpatents

Carlisle, Keith [Discovery Bay, CA

2003-04-08

An apparatus and method is utilized to measure relative rigid body motion between two bodies by measuring linear motion in the principal axis and linear motion in an orthogonal axis. From such measurements it is possible to obtain displacement, departure from straightness, and angular displacement from the principal axis of a rigid body.

Periodic organization of the contractile apparatus in smooth muscle revealed by the motion of dense bodies in single cells.

PubMed

Kargacin, G J; Cooke, P H; Abramson, S B; Fay, F S

1989-04-01

To study the organization of the contractile apparatus in smooth muscle and its behavior during shortening, the movement of dense bodies in contracting saponin skinned, isolated cells was analyzed from digital images collected at fixed time intervals. These cells were optically lucent so that punctate structures, identified immunocytochemically as dense bodies, were visible in them with the phase contrast microscope. Methods were adapted and developed to track the bodies and to study their relative motion. Analysis of their tracks or trajectories indicated that the bodies did not move passively as cells shortened and that nearby bodies often had similar patterns of motion. Analysis of the relative motion of the bodies indicated that some bodies were structurally linked to one another or constrained so that the distance between them remained relatively constant during contraction. Such bodies tended to fall into laterally oriented, semirigid groups found at approximately 6-microns intervals along the cell axis. Other dense bodies moved rapidly toward one another axially during contraction. Such bodies were often members of separate semirigid groups. This suggests that the semirigid groups of dense bodies in smooth muscle cells may provide a framework for the attachment of the contractile structures to the cytoskeleton and the cell surface and indicates that smooth muscle may be more well-ordered than previously thought. The methods described here for the analysis of the motion of intracellular structures should be directly applicable to the study of motion in other cell types.

Chicxulub's Cretaceous-Tertiary Boundary Twin Crater. Was There a Double Impact in the Yucatan Peninsula?

NASA Astrophysics Data System (ADS)

Camargo, A. Z.; Juarez, J. S.

2004-05-01

In 1980, Alvarez and co-authors proposed that the K/T extinctions were caused by the effects of a celestial body falling on Earth. After a long search for the impact site, the 1981 work by Penfield and Camargo on a 170 km structure in the Yucatan Peninsula got the attention of the specialists, and it was later proved that it was the crater created by the impact of that celestial body. New data suggests the existence of a second impact crater close to Chicxulub, both being of the same age and created by two fragments of the same celestial boby. A new magnetic map plotted as a color-coded shaded relief surface, reveals a feature not evident before: two interlaced ringed anomalies of about 100 and 50 km diameters, the larger one related to the magnetic signature of the Chicxulub Crater, and the second located at its E-SE edge. The 50 km anomaly, with morphology similar to Chicxulub's, is interpreted as also corresponding to an impact crater, centered at about 89 Deg. Long. W and 21 Deg. Lat. N, close to the city of Izamal. The anomaly size indicates that the diameter of the IZAMAL CRATER is about 85 km. The Chicxulub Crater, being buried under several hundred meters of Tertiary carbonate rocks, is not visible from the surface or from space; although some surface expression of its morphology has been reported. The best known is the ring of cenotes (sink holes) at the crater's rim, visible on satellite images and photographs. The JPL/NASA image PIA03379, is a color-coded shaded relief image of terrain elevation in which the topography was exagerated to highlight the Chicxulub Crater rim. On this image, a semi circular arc of dark spots is also visible immediately to the E-SE of the Chicxulub Crater rim. These spots are interpreted as large irregular karstic depressions, similar to the ones along the cenote ring of Chicxulub. On the evidence of the spatial relationship of the magnetic anomalies and the satellite image features, we tested how well the proposed Izamal Crater would fit the karstic depressions E-SE of the Chicxulub crater. We found that an 82 km diameter circle fits well the semi circle of dark spots, and interpret it as a portion of the rim of the IZAMAL impact crater. The interpreted relationships and origin of the Chicxulub and Izamal craters are: The Chicxulub crater was created after Izamal. They were created by two different impact bodies. The craters are of the same age. They were formed by two parts of the same celestial body, the MAYA BOLIDE. The diameter of the fragment impacted in Izamal is estimated to be about 4 km. This finding has implications on studies related to the K/T extinction event. Some scientists argue that the Chicxulub crater is somewhat small to account for the global K/T extinction all by itself. The double impact may account for the observed effects. Also, multiple impacts at sea may have put into the atmosphere much more sea water salts capable of dissociating into damaging chlorine compounds. Furthermore, the impact sequence may help explain the origin of the K/T boundary glasses from Haiti and better define the ballistic trajectories of the impacts ejecta and its effects on the extinctions. And the Maya Bolide orbit can be investigated to define its origin and characteristics as a comet or asteroid.

Patterns of fMRI activity dissociate overlapping functional brain areas that respond to biological motion.

PubMed

Peelen, Marius V; Wiggett, Alison J; Downing, Paul E

2006-03-16

Accurate perception of the actions and intentions of other people is essential for successful interactions in a social environment. Several cortical areas that support this process respond selectively in fMRI to static and dynamic displays of human bodies and faces. Here we apply pattern-analysis techniques to arrive at a new understanding of the neural response to biological motion. Functionally defined body-, face-, and motion-selective visual areas all responded significantly to "point-light" human motion. Strikingly, however, only body selectivity was correlated, on a voxel-by-voxel basis, with biological motion selectivity. We conclude that (1) biological motion, through the process of structure-from-motion, engages areas involved in the analysis of the static human form; (2) body-selective regions in posterior fusiform gyrus and posterior inferior temporal sulcus overlap with, but are distinct from, face- and motion-selective regions; (3) the interpretation of region-of-interest findings may be substantially altered when multiple patterns of selectivity are considered.

Expression of Cassini's third law for Callisto, and theory of its rotation

NASA Astrophysics Data System (ADS)

Noyelles, Benoît

2009-07-01

The rotation of the main natural satellites of the Solar System is widely assumed to be synchronous, because this corresponds to an equilibrium state. In the case of the Moon, 3 laws have been formulated by Cassini, assuming a spin-orbit resonance and a 1:1 nodal resonance. The recent gravitational data collected by the spacecrafts Galileo (in the jovian system) and Cassini (in the saturnian system) allows us to study the rotation of other natural satellites, and to check the universality of Cassini's laws. This paper deals with the rotation of the Galilean satellites of Jupiter J-4 Callisto. In this study we use both analytical (like Lie transforms) and numerical methods (numerical detection of chaos, numerical integration, frequency analysis) to first check the reliability of Cassini Laws for Callisto, and then to give a first theory of its rotation, Callisto's being considered as a rigid body. We first show that the Third Cassini Law (i.e. the nodal resonance), is not satisfied in every reference frame, in particular in the most natural one (i.e. the J2000 jovian equator). The difference of the nodes presents a chaotic-like behavior, that we prove to be just a geometrical illusion. Moreover, we give a mathematical condition ruling the choice of an inertial reference frame in which the Third Cassini Law is fulfilled. Secondly, we give a theory of Callisto's rotation in the International Celestial Reference Frame (ICRF). We highlight a small motion (i.e. <200 m) of its rotation axis about its body figure, a 11.86-yr periodicity in Callisto's length-of-day, and the proximity of a resonance that forces 182-yr librations in Callisto's obliquity.

Spacetime and orbits of bumpy black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vigeland, Sarah J.; Hughes, Scott A.

2010-01-15

Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced ''bumpy black holes'': objects that are almost, but not quite, general relativity's black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation ismore » zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes--objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime's bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track the orbital phase of a small orbiting body. We find that in the weak field, orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is many times greater than would be predicted from a Newtonian analysis, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime's multipoles deviate from the black hole expectation.« less

Accurate Determination of Comet and Asteroid Orbits Leading to Collision With Earth

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Kay-Bunnell, Linda; Mazanek, Daniel D.; Kumar, Renjith R.; Seywald, Hans; Hausman, Matthew A.

2005-01-01

Movements of the celestial bodies in our solar system inspired Isaac Newton to work out his profound laws of gravitation and motion; with one or two notable exceptions, all of those objects move as Newton said they would. But normally harmonious orbital motion is accompanied by the risk of collision, which can be cataclysmic. The Earth s moon is thought to have been produced by such an event, and we recently witnessed magnificent bombardments of Jupiter by several pieces of what was once Comet Shoemaker-Levy 9. Other comets or asteroids may have met the Earth with such violence that dinosaurs and other forms of life became extinct; it is this possibility that causes us to ask how the human species might avoid a similar catastrophe, and the answer requires a thorough understanding of orbital motion. The two red square flags with black square centers displayed are internationally recognized as a warning of an impending hurricane. Mariners and coastal residents who know the meaning of this symbol and the signs evident in the sky and ocean can act in advance to try to protect lives and property; someone who is unfamiliar with the warning signs or chooses to ignore them is in much greater jeopardy. Although collisions between Earth and large comets or asteroids occur much less frequently than landfall of a hurricane, it is imperative that we learn to identify the harbingers of such collisions by careful examination of an object s path. An accurate determination of the orbit of a comet or asteroid is necessary in order to know if, when, and where on the Earth s surface a collision will occur. Generally speaking, the longer the warning time, the better the chance of being able to plan and execute action to prevent a collision. The more accurate the determination of an orbit, the less likely such action will be wasted effort or, what is worse, an effort that increases rather than decreases the probability of a collision. Conditions necessary for a collision to occur are discussed, and warning times for long-period comets and near-Earth asteroids are presented.

Changes in apparent body orientation and sensory localization induced by vibration of postural muscles - Vibratory myesthetic illusions

NASA Technical Reports Server (NTRS)

Lackner, J. R.; Levine, M. S.

1979-01-01

Human experiments are carried out which support the observation of Goodwin (1973) and Goodwin et al. (1972) that vibration of skeletal muscles can elicit illusory limb motion. These experiments extend the class of possible myesthetic illusions by showing that vibration of the appropriate muscles can produce illusory body motion in nearly any desired direction. Such illusory changes in posture occur only when visual information about body orientation is absent; these changes in apparent posture are sometimes accompanied by a slow-phase nystagmus that compensates for the direction of apparent body motion. During illusory body motion a stationary target light that is fixated will appear to move with the body at the same apparent velocity. However, this pattern of apparent body motion and conjoint visual - defined as propriogyral illusion - is suppressed if the subject is in a fully illuminated environment providing cues about true body orientation. Persuasive evidence is thus provided for the contribution of both muscle afferent and touch-pressure information to the supraspinal mechanisms that determine apparent orientation on the basis of ongoing patterns of interoceptive and exteroceptive activity.

Importance of body rotation during the flight of a butterfly.

PubMed

Fei, Yueh-Han John; Yang, Jing-Tang

2016-03-01

In nature the body motion of a butterfly is clearly observed to involve periodic rotation and varied flight modes. The maneuvers of a butterfly in flight are unique. Based on the flight motion of butterflies (Kallima inachus) recorded in free flight, a numerical model of a butterfly is created to study how its flight relates to body pose; the body motion in a simulation is prescribed and tested with varied initial body angle and rotational amplitude. A butterfly rotates its body to control the direction of the vortex rings generated during flapping flight; the flight modes are found to be closely related to the body motion of a butterfly. When the initial body angle increases, the forward displacement decreases, but the upward displacement increases within a stroke. With increased rotational amplitudes, the jet flows generated by a butterfly eject more downward and further enhance the generation of upward force, according to which a butterfly executes a vertical jump at the end of the downstroke. During this jumping stage, the air relative to the butterfly is moving downward; the butterfly pitches up its body to be parallel to the flow and to decrease the projected area so as to avoid further downward force generated. Our results indicate the importance of the body motion of a butterfly in flight. The inspiration of flight controlled with body motion from the flight of a butterfly might yield an alternative way to control future flight vehicles.

The internal structure of the planets Mercury, Venus, Mars and Jupiter according to the Savic-Kasanin theory

NASA Astrophysics Data System (ADS)

Savic, P.

The internal structure of Mercury, Venus, Mars, and Jupiter is considered in the framework of the Savic-Kasanin theory of the behavior of materials under high pressure. The main hypothesis underlying the theory is based on the deformation of the electron shells by the dislocation and ejection of electrons from atoms in a given material. This theory is discussed in relation to the spontaneous effect of gravitation and cooling on atoms in the material of a celestial body.

The origin of rotation, dense matter physics and all that: a tribute to Pavle Savić.

NASA Astrophysics Data System (ADS)

Čelebonović, V.

1995-04-01

This is a review of the main physical ideas and examples of applicability in astrophysics and pure physics of a semiclassical theory of dense matter proposed by Pavle Savićand Radivoje Kašanin in the early sixties. A hypothesis, advanced by Savić with the aim of solving the problem of the origin of rotation of celestial bodies, will also be discussed. The paper is dedicated to the memory of Pavle Savić.

LDEF grappled by remote manipulator system (RMS) during STS-32 retrieval

NASA Image and Video Library

1990-01-20

This view taken through overhead window W7 on Columbia's, Orbiter Vehicle (OV) 102's, aft flight deck shows the Long Duration Exposure Facility (LDEF) in the grasp of the remote manipulator system (RMS) during STS-32 retrieval activities. Other cameras at eye level were documenting the bus-sized spacecraft at various angles as the RMS manipulated LDEF for a lengthy photo survey. The glaring celestial body in the upper left is the sun with the Earth's surface visible below.

A reduced-dimensionality approach to uncovering dyadic modes of body motion in conversations.

PubMed

Gaziv, Guy; Noy, Lior; Liron, Yuvalal; Alon, Uri

2017-01-01

Face-to-face conversations are central to human communication and a fascinating example of joint action. Beyond verbal content, one of the primary ways in which information is conveyed in conversations is body language. Body motion in natural conversations has been difficult to study precisely due to the large number of coordinates at play. There is need for fresh approaches to analyze and understand the data, in order to ask whether dyads show basic building blocks of coupled motion. Here we present a method for analyzing body motion during joint action using depth-sensing cameras, and use it to analyze a sample of scientific conversations. Our method consists of three steps: defining modes of body motion of individual participants, defining dyadic modes made of combinations of these individual modes, and lastly defining motion motifs as dyadic modes that occur significantly more often than expected given the single-person motion statistics. As a proof-of-concept, we analyze the motion of 12 dyads of scientists measured using two Microsoft Kinect cameras. In our sample, we find that out of many possible modes, only two were motion motifs: synchronized parallel torso motion in which the participants swayed from side to side in sync, and still segments where neither person moved. We find evidence of dyad individuality in the use of motion modes. For a randomly selected subset of 5 dyads, this individuality was maintained for at least 6 months. The present approach to simplify complex motion data and to define motion motifs may be used to understand other joint tasks and interactions. The analysis tools developed here and the motion dataset are publicly available.

A reduced-dimensionality approach to uncovering dyadic modes of body motion in conversations

PubMed Central

Noy, Lior; Liron, Yuvalal; Alon, Uri

2017-01-01

Face-to-face conversations are central to human communication and a fascinating example of joint action. Beyond verbal content, one of the primary ways in which information is conveyed in conversations is body language. Body motion in natural conversations has been difficult to study precisely due to the large number of coordinates at play. There is need for fresh approaches to analyze and understand the data, in order to ask whether dyads show basic building blocks of coupled motion. Here we present a method for analyzing body motion during joint action using depth-sensing cameras, and use it to analyze a sample of scientific conversations. Our method consists of three steps: defining modes of body motion of individual participants, defining dyadic modes made of combinations of these individual modes, and lastly defining motion motifs as dyadic modes that occur significantly more often than expected given the single-person motion statistics. As a proof-of-concept, we analyze the motion of 12 dyads of scientists measured using two Microsoft Kinect cameras. In our sample, we find that out of many possible modes, only two were motion motifs: synchronized parallel torso motion in which the participants swayed from side to side in sync, and still segments where neither person moved. We find evidence of dyad individuality in the use of motion modes. For a randomly selected subset of 5 dyads, this individuality was maintained for at least 6 months. The present approach to simplify complex motion data and to define motion motifs may be used to understand other joint tasks and interactions. The analysis tools developed here and the motion dataset are publicly available. PMID:28141861

A Learning Support System Regarding Motion Trigger for Repetitive Motion Having an Operating Instrument

ERIC Educational Resources Information Center

Toyooka, Hiroshi; Matsuura, Kenji; Gotoda, Naka

2016-01-01

In the learning support for repetitive motions having an operating instrument, it is necessary for learners to control not only their own body motions but also an instrument corresponding to the body. This study focuses on the repetitive motion learning using single operation instrument without the movement in space; i.e. jump-rope and hula-hoop.…

Recovery of biological motion perception and network plasticity after cerebellar tumor removal.

PubMed

Sokolov, Arseny A; Erb, Michael; Grodd, Wolfgang; Tatagiba, Marcos S; Frackowiak, Richard S J; Pavlova, Marina A

2014-10-01

Visual perception of body motion is vital for everyday activities such as social interaction, motor learning or car driving. Tumors to the left lateral cerebellum impair visual perception of body motion. However, compensatory potential after cerebellar damage and underlying neural mechanisms remain unknown. In the present study, visual sensitivity to point-light body motion was psychophysically assessed in patient SL with dysplastic gangliocytoma (Lhermitte-Duclos disease) to the left cerebellum before and after neurosurgery, and in a group of healthy matched controls. Brain activity during processing of body motion was assessed by functional magnetic resonance imaging (MRI). Alterations in underlying cerebro-cerebellar circuitry were studied by psychophysiological interaction (PPI) analysis. Visual sensitivity to body motion in patient SL before neurosurgery was substantially lower than in controls, with significant improvement after neurosurgery. Functional MRI in patient SL revealed a similar pattern of cerebellar activation during biological motion processing as in healthy participants, but located more medially, in the left cerebellar lobules III and IX. As in normalcy, PPI analysis showed cerebellar communication with a region in the superior temporal sulcus, but located more anteriorly. The findings demonstrate a potential for recovery of visual body motion processing after cerebellar damage, likely mediated by topographic shifts within the corresponding cerebro-cerebellar circuitry induced by cerebellar reorganization. The outcome is of importance for further understanding of cerebellar plasticity and neural circuits underpinning visual social cognition.

Effect of vision and stance width on human body motion when standing: implications for afferent control of lateral sway.

PubMed

Day, B L; Steiger, M J; Thompson, P D; Marsden, C D

1993-09-01

1. Measurements of human upright body movements in three dimensions have been made on thirty-five male subjects attempting to stand still with various stance widths and with eyes closed or open. Body motion was inferred from movements of eight markers fixed to specific sites on the body from the shoulders to the ankles. Motion of these markers was recorded together with motion of the point of application of the resultant of the ground reaction forces (centre of pressure). 2. The speed of the body (average from eight sites) was increased by closing the eyes or narrowing the stance width and there was an interaction between these two factors such that vision reduced body speed more effectively when the feet were closer together. Similar relationships were found for components of velocity both in the frontal and sagittal planes although stance width exerted a much greater influence on the lateral velocity component. 3. Fluctuations in position of the body were also increased by eye closure or narrowing of stance width. Again, the effect of stance width was more potent for lateral than for anteroposterior movements. In contrast to the velocity measurements, there was no interaction between vision and stance width. 4. There was a progressive increase in the amplitude of position and velocity fluctuations from markers placed higher on the body. The fluctuations in the position of the centre of pressure were similar in magnitude to those of the markers placed near the hip. The fluctuations in velocity of centre of pressure, however, were greater than of any site on the body. 5. Analysis of the amplitude of angular motion between adjacent straight line segments joining the markers suggests that the inverted pendulum model of body sway is incomplete. Motion about the ankle joint was dominant only for lateral movement in the frontal plane with narrow stance widths (< 8 cm). For all other conditions most angular motion occurred between the trunk and leg. 6. The large reduction in lateral body motion with increasing stance width was mainly due to a disproportionate reduction in the angular motion about the ankles and feet. A mathematical model of the skeletal structure has been constructed which offers some explanation for this specific reduction in joint motion.(ABSTRACT TRUNCATED AT 400 WORDS)

Spatial water maze learning using celestial cues by the meadow vole, Microtus pennsylvanicus.

PubMed

Kavaliers, M; Galea, L A

1994-03-31

The Morris water maze is widely used to evaluate to evaluate the spatial learning ability of rodents under laboratory settings. The present study demonstrates that reproductive male meadow voles, Microtus pennsylvanicus, are able to acquire and retain a spatial water maze task using celestial cues. Voles were able to acquire a modified outdoor Morris water maze task over 4 trials per day, whereby they had to learn and remember the location of a submerged hidden platform, using the position of the sun and associated celestial cues. Their proficiency on this task was related to the availability of the celestial cues, with voles displaying significantly poorer spatial navigation on overcast than clear days and when the testing time (and position of the sun and associated celestial cues) was shifted from morning to afternoon. These findings with meadow voles support the ecological relevance of the water maze task.

Design of all-weather celestial navigation system

NASA Astrophysics Data System (ADS)

Sun, Hongchi; Mu, Rongjun; Du, Huajun; Wu, Peng

2018-03-01

In order to realize autonomous navigation in the atmosphere, an all-weather celestial navigation system is designed. The research of celestial navigation system include discrimination method of comentropy and the adaptive navigation algorithm based on the P value. The discrimination method of comentropy is studied to realize the independent switching of two celestial navigation modes, starlight and radio. Finally, an adaptive filtering algorithm based on P value is proposed, which can greatly improve the disturbance rejection capability of the system. The experimental results show that the accuracy of the three axis attitude is better than 10″, and it can work all weather. In perturbation environment, the position accuracy of the integrated navigation system can be increased 20% comparing with the traditional method. It basically meets the requirements of the all-weather celestial navigation system, and it has the ability of stability, reliability, high accuracy and strong anti-interference.

On the motion of a rigid body with an internal moving point mass on a horizontal plane

NASA Astrophysics Data System (ADS)

Bardin, B. S.; Panev, A. S.

2018-05-01

We consider motions of a body carrying movable internal mass. The internal mass is a particle moving in a circle inside the body, which performs a rectilinear motion on a horizontal plane. We suppose that viscous and dry friction acts between the plane and the body. We also assume that the body moves without jumps on the plane. Our study has shown that depending on values of parameters the body moves either periodically stoping and resting for certain time intervals or it approaches a periodic mode of motion without quiescence intervals. The above conclusions are in good correspondence with results obtained in our previous papers, where the above problem has been studied under assumption that the viscous friction is absent.

Small Bodies, Big Discoveries: NASA's Small Bodies Education Program

NASA Astrophysics Data System (ADS)

Mayo, L.; Erickson, K. J.

2014-12-01

2014 is turning out to be a watershed year for celestial events involving the solar system's unsung heroes, small bodies. This includes the close flyby of comet C/2013 A1 / Siding Spring with Mars in October and the historic Rosetta mission with its Philae lander to comet 67P/Churyumov-Gerasimenko. Beyond 2014, the much anticipated 2015 Pluto flyby by New Horizons and the February Dawn Mission arrival at Ceres will take center stage. To deliver the excitement and wonder of our solar system's small bodies to worldwide audiences, NASA's JPL and GSFC education teams in partnership with NASA EDGE will reach out to the public through multiple venues including broadcast media, social media, science and math focused educational activities, observing challenges, interactive visualization tools like "Eyes on the Solar System" and more. This talk will highlight NASA's focused education effort to engage the public in small bodies mission science and the role these objects play in our understanding of the formation and evolution of the solar system.

Numerical simulation of rotating body movement in medium with various densities

NASA Astrophysics Data System (ADS)

Tenenev, Valentin A.; Korolev, Stanislav A.; Rusyak, Ivan G.

2016-10-01

The paper proposes an approach to calculate the motion of rotating bodies in resisting medium by solving the Kirchhoff equations of motion in a coordinate system moving with the body and in determination of aerodynamic characteristics of the body with a given geometry by solving the Navier-Stokes equations. We present the phase trajectories of the perturbed motion of a rotating projectile in media with different densities: gas and liquid.

Orientation of selective effects of body tilt on visually induced perception of self-motion.

PubMed

Nakamura, S; Shimojo, S

1998-10-01

We examined the effect of body posture upon visually induced perception of self-motion (vection) with various angles of observer's tilt. The experiment indicated that the tilted body of observer could enhance perceived strength of vertical vection, while there was no effect of body tilt on horizontal vection. This result suggests that there is an interaction between the effects of visual and vestibular information on perception of self-motion.

Mechanism test bed. Flexible body model report

NASA Technical Reports Server (NTRS)

Compton, Jimmy

1991-01-01

The Space Station Mechanism Test Bed is a six degree-of-freedom motion simulation facility used to evaluate docking and berthing hardware mechanisms. A generalized rigid body math model was developed which allowed the computation of vehicle relative motion in six DOF due to forces and moments from mechanism contact, attitude control systems, and gravity. No vehicle size limitations were imposed in the model. The equations of motion were based on Hill's equations for translational motion with respect to a nominal circular earth orbit and Newton-Euler equations for rotational motion. This rigid body model and supporting software were being refined.

Relativistic problems on astronomical constants.

NASA Astrophysics Data System (ADS)

Tao, Jinhe; Huang, Tianyi

1999-06-01

The fact that modern astronomical observational technique has made rapid progress and the 1PN approximation of general relativity has been extensively applied in celestial mechanics and astrometry, makes it is necessary to investigate and examine the system of astronomical constants carefully and rigorously in the relativistic framework. The mass of a celestial body in the solar system should be defined as its BD mass that changes relatively in an amount less than 10-19 and could be considered as a constant. The equations satisfied by the gravitational potentials are not Poisson equations anymore but depend on the choice of the coordinate gauge. Therefore the gravitational potentials cannot be expanded in the traditional harmonics. It is neccessary to choose the coordinate gauge and take BD multipole moments as astronomical constants. The obliquity of the ecliptic has been determined in high precision and it would be neccessary to give a conventional definition of the 1PN ecliptic. A relativistic definition of the geoid is important and left to be discussed. The astronomical constants that relate the units of time and length have been clearly defined but need to be clarified to avoid their misuse.

On the Definition of Aberration

NASA Astrophysics Data System (ADS)

Xu, Minghui; Wang, Guangli

2014-12-01

There was a groundbreaking step in the history of astronomy in 1728 when the effect of aberration was discovered by James Bradley (1693-1762). Recently, the solar acceleration, due to the variations in the aberrational effect of extragalactic sources caused by it, has been determined from VLBI observations with an uncertainty of about 0.5 mm{\\cdot}{s^{-1}}{\\cdot}{yr^{-1}} level. As a basic concept in astrometry with a nearly 300-year history, the definition of aberration, however, is still equivocal and discordant in the literature. It has been under continuing debate whether it depends on the relative motion between the observer and the observed source or only on the motion of the observer with respect to the frame of reference. In this paper, we will review the debate and the inconsistency in the definition of the aberration since the last century, and then discuss its definition in detail, which involves the discussions on the planetary aberration, the stellar aberration, the proper motion of an object during the travel time of light from the object to the observer, and the way of selecting the reference frame to express and distinguish the motions of the source and the observer. The aberration is essentially caused by the transformation between coordinate systems, and consequently quantified by the velocity of the observer with respect to the selected reference frame, independent of the motion of the source. Obviously, this nature is totally different from that of the definition given by the IAU WG NFA (Capitaine, 2007) in 2006, which is stated as, ``the apparent angular displacement of the observed position of a celestial object from its geometric position, caused by the finite velocity of light in combination with the motions of the observer and of the observed object.''

A Deep Space Orbit Determination Software: Overview and Event Prediction Capability

NASA Astrophysics Data System (ADS)

Kim, Youngkwang; Park, Sang-Young; Lee, Eunji; Kim, Minsik

2017-06-01

This paper presents an overview of deep space orbit determination software (DSODS), as well as validation and verification results on its event prediction capabilities. DSODS was developed in the MATLAB object-oriented programming environment to support the Korea Pathfinder Lunar Orbiter (KPLO) mission. DSODS has three major capabilities: celestial event prediction for spacecraft, orbit determination with deep space network (DSN) tracking data, and DSN tracking data simulation. To achieve its functionality requirements, DSODS consists of four modules: orbit propagation (OP), event prediction (EP), data simulation (DS), and orbit determination (OD) modules. This paper explains the highest-level data flows between modules in event prediction, orbit determination, and tracking data simulation processes. Furthermore, to address the event prediction capability of DSODS, this paper introduces OP and EP modules. The role of the OP module is to handle time and coordinate system conversions, to propagate spacecraft trajectories, and to handle the ephemerides of spacecraft and celestial bodies. Currently, the OP module utilizes the General Mission Analysis Tool (GMAT) as a third-party software component for highfidelity deep space propagation, as well as time and coordinate system conversions. The role of the EP module is to predict celestial events, including eclipses, and ground station visibilities, and this paper presents the functionality requirements of the EP module. The validation and verification results show that, for most cases, event prediction errors were less than 10 millisec when compared with flight proven mission analysis tools such as GMAT and Systems Tool Kit (STK). Thus, we conclude that DSODS is capable of predicting events for the KPLO in real mission applications.

The rotational elements of Mars and its satellites

NASA Astrophysics Data System (ADS)

Jacobson, R. A.; Konopliv, A. S.; Park, R. S.; Folkner, W. M.

2018-03-01

The International Astronomical Union (IAU) defines planet and satellite coordinate systems relative to their axis of rotation and the angle about that axis. The rotational elements of the bodies are the right ascension and declination of the rotation axis in the International Celestial Reference Frame and the rotation angle, W, measured easterly along the body's equator. The IAU specifies the location of the body's prime meridian by providing a value for W at epoch J2000. We provide new trigonometric series representations of the rotational elements of Mars and its satellites, Phobos and Deimos. The series for Mars are from a least squares fit to the rotation model used to orient the Martian gravity field. The series for the satellites are from a least squares fit to rotation models developed in accordance with IAU conventions from recent ephemerides.

Theories of comets to the age of Laplace

NASA Astrophysics Data System (ADS)

Heidarzadeh, Tofigh

Although the development of ideas about cometary motion has been investigated in several projects, a comprehensive and detailed survey of physical theories of comets has not been conducted. The available works either illustrate relatively short periods in the history of physical cometology or portray a landscape view without adequate details. The present study is an attempt to depict the details of the major physical theories of comets from Aristotle to the age of Laplace. The basic question from which this project originated was simple: how did natural philosophers and astronomers define the nature and place of a new category of celestial objects--the comets--after Brahe's estimation of cometary distances? However, a study starting merely from Brahe without covering classical and medieval thought about comets would be incomplete. Thus, based on the fundamental physical characteristics attributed to comets, the history of cometology may be divided into three periods: from Aristotle to Brahe, in which comets were assumed to be meteorological phenomena; from Brahe to Newton, when comets were admitted as celestial bodies but with unknown trajectories; and from Newton to Laplace, in which they were treated as members of the solar system having more or less the same properties of the planets. By estimating the mass of comets in the 1800s, Laplace diverted cometology into a different direction wherein they were considered among the smallest bodies in the solar system and deprived of the most important properties that had been used to explain their physical constitution during the previous two millennia. Ideas about the astrological aspects of comets are not considered in this study. Also, topics concerning the motion of comets are explained to the extent that is helpful in illustrating their physical properties. The main objective is to demonstrate the foundations of physical theories of comets, and the interaction between observational and mathematical astronomy, and the physical sciences in defining the properties of comets. The number of publications containing ideas about the physical properties of comets shows a radical increase in the third period of our account of cometology. From numerous general astronomy texts or treatises devoted to comets in this period, those were discussed here that either proposed a different theory of comets or criticized the physical aspects of contemporary theories. The survey includes only works published in England and France, and a few in German-speaking countries. Although Laplace's achievement in estimation of cometary masses became the basis of modern cometology, our current ideas about the actual size, mass and composition of comets, and the processes by which the coma and tail are formed have been developed only since the mid twentieth century. Post-Laplacian developments in the study of comets are highlighted in an appendix, which briefly reviews the major achievements in the observational and theoretical study of comets in the nineteenth and the twentieth centuries. Although the present study is mainly focused on the physical theories of comets, its results will be relevant to studies in the history of geology, planetary science, and astrology. On the other hand, those results may initiate new studies about educational practices for physics and astronomy in post- Newtonian Europe, the ways that different parts of Newton's physical, astronomical and cosmological ideas evolved after him, and the influence of cometary studies on the foundation of astrophysics.

Free and controlled motion of a body with a moving internal mass through a fluid in the presence of circulation around the body

NASA Astrophysics Data System (ADS)

Vetchanin, E. V.; Kilin, A. A.

2016-01-01

The free and controlled motion of an arbitrary two-dimensional body with a moving internal mass and constant circulation around the body in an ideal fluid is studied. Bifurcation analysis of the free motion is performed (under the condition of a fixed internal mass). It is shown that the body can be moved to a given point by varying the position of the internal mass. Some problems related to the presence of a nonzero drift of the body with a fixed internal mass are noted.

Modeling Attitude Dynamics in Simulink: A Study of the Rotational and Translational Motion of a Spacecraft Given Torques and Impulses Generated by RMS Hand Controllers

NASA Technical Reports Server (NTRS)

Mauldin, Rebecca H.

2010-01-01

In order to study and control the attitude of a spacecraft, it is necessary to understand the natural motion of a body in orbit. Assuming a spacecraft to be a rigid body, dynamics describes the complete motion of the vehicle by the translational and rotational motion of the body. The Simulink Attitude Analysis Model applies the equations of rigid body motion to the study of a spacecraft?s attitude in orbit. Using a TCP/IP connection, Matlab reads the values of the Remote Manipulator System (RMS) hand controllers and passes them to Simulink as specified torque and impulse profiles. Simulink then uses the governing kinematic and dynamic equations of a rigid body in low earth orbit (LE0) to plot the attitude response of a spacecraft for five seconds given known applied torques and impulses, and constant principal moments of inertia.

Principles of Celestial Navigation: An Online Resource for Introducing Practical Astronomy to the Public

NASA Astrophysics Data System (ADS)

Urban, Sean E.

2015-08-01

Astronomy is often called a "gateway" science because it inspires appreciation and awe among children and non-scientists. Applied astronomy, with practical, real-world applications, can entice even the most utilitarian people to take notice and learn about the subject. Traditional celestial navigation is an astronomy topic that captures the attention of the public. The U.S. Naval Observatory has led the development of a publicly available online celestial navigation educational module titled, "Principles of Celestial Navigation". It can be used world-wide to introduce people to astronomy. This poster describes some of the aspects of this teaching module.

Reclaiming Celestial Navigation Using a Contemporary Hawaiian Worldview of the Heavens

NASA Astrophysics Data System (ADS)

Dye, Ahia G.; Ha`o, Celeste; Slater, Timothy F.; Slater, Stephanie J.

2015-08-01

The immense challenges of successfully navigating the vast Pacific basin without modern instruments are well-known. At the same time, the precise methods used by ancient Polynesian wayfinders are largely undocumented, the strategies being wholly unfamiliar to early European navigators from higher latitudes with formal training in charts and tables. Leading the wave of a Hawaiian-Renaissance, contemporary Hawaiian seafarers are boldly reclaiming their heritage by recreating and sailing double hulled canoes by instrument-free, navigation techniques. Many of these navigational techniques are probably reminiscent of earlier strategies, and are proving to be highly successful. The result is that numerous canoes are now making repeated trips throughout the Polynesian Triangle, and reaching beyond to soon circumnavigate the globe. Not surprisingly, a vital component of any navigational system far from terrestrial landmarks is based on the changing positions and predictable motions of the Sun and stars. Although many of the indigenous star names are lost to history, some of the most important star names for celestial navigation have been painstakingly re-claimed. Other critically important navigational stars are being named by the respected Hawaiian Guild Navigators and their teams of educators who are conducting navigation training for Hawaiian sailing crews. The authors are collecting and documenting these new star names along-with their identifiable asterisms-in the service of educating both the public and the next generation of navigators.

The Celestial Basis of Civilization

NASA Astrophysics Data System (ADS)

Masse, W. B.

Scholars have long puzzled over the reasons for the ubiquity of celestial images in the residue of the world's earliest civilizations: in art, myth, religious cosmology, iconography, cosmogony, eschatological beliefs, and as portents for the conduct of royal and chiefly power. The general consensus is that these images represented a need by early societies to use the fixed celestial heavens in order to regulate ritual and agricultural cycles, and to satisfy a psychological need by people to relate themselves to their surrounding Universe. Such explanations are facile and miss an important aspect of the celestial heavens. The fixed celestial heavens served as the back-drop for a large number of often spectacular temporary naked-eye visible celestial events which animated the night and sometimes the daytime sky, and which created an 'otherworld' for virtually all cultural groups. In this paper I present a model derived from the detailed analysis of Hawaiian oral traditions and culture history in relation to historic astronomical records of temporary celestial events, and then apply this model to cultural traditions from Mesoamerica and other geographic regions in order to demonstrate that novae, supernovae, variable stars, comets, great meteor showers, aurorae, solar and lunar eclipses, and impacting Solar System debris, together played a critical role in the artistic, intellectual, and political development of early civilizations. These data not only provide important insights into the development of civilization, but also provide important details and longitudinal records of astronomical events and phenomena which are otherwise not readily available for scientific scrutiny.

Being Moved by the Self and Others: Influence of Empathy on Self-Motion Perception

PubMed Central

Lopez, Christophe; Falconer, Caroline J.; Mast, Fred W.

2013-01-01

Background The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion. Methodology/Principal Findings We investigated whether viewing our own body, the body of another, and an object in motion influences self-motion perception. We found a visual-vestibular congruency effect for self-motion perception when observing self and object motion, and a reduction in this effect when observing someone else's body motion. The congruency effect was correlated with empathy scores, revealing the importance of empathy in mirroring mechanisms. Conclusions/Significance The data show that vestibular perception is modulated by agent-specific mirroring mechanisms. The observation of conspecifics in motion is an essential component of social life, and self-motion perception is crucial for the distinction between the self and the other. Finally, our results hint at the presence of a “vestibular mirror neuron system”. PMID:23326302

The MPI Emotional Body Expressions Database for Narrative Scenarios

PubMed Central

Volkova, Ekaterina; de la Rosa, Stephan; Bülthoff, Heinrich H.; Mohler, Betty

2014-01-01

Emotion expression in human-human interaction takes place via various types of information, including body motion. Research on the perceptual-cognitive mechanisms underlying the processing of natural emotional body language can benefit greatly from datasets of natural emotional body expressions that facilitate stimulus manipulation and analysis. The existing databases have so far focused on few emotion categories which display predominantly prototypical, exaggerated emotion expressions. Moreover, many of these databases consist of video recordings which limit the ability to manipulate and analyse the physical properties of these stimuli. We present a new database consisting of a large set (over 1400) of natural emotional body expressions typical of monologues. To achieve close-to-natural emotional body expressions, amateur actors were narrating coherent stories while their body movements were recorded with motion capture technology. The resulting 3-dimensional motion data recorded at a high frame rate (120 frames per second) provides fine-grained information about body movements and allows the manipulation of movement on a body joint basis. For each expression it gives the positions and orientations in space of 23 body joints for every frame. We report the results of physical motion properties analysis and of an emotion categorisation study. The reactions of observers from the emotion categorisation study are included in the database. Moreover, we recorded the intended emotion expression for each motion sequence from the actor to allow for investigations regarding the link between intended and perceived emotions. The motion sequences along with the accompanying information are made available in a searchable MPI Emotional Body Expression Database. We hope that this database will enable researchers to study expression and perception of naturally occurring emotional body expressions in greater depth. PMID:25461382

Controlled Wake of a Moving Axisymmetric Bluff Body

NASA Astrophysics Data System (ADS)

Lee, E.; Vukasinovic, B.; Glezer, A.

2017-11-01

The aerodynamic loads exerted on a wire-mounted axisymmetric bluff body in prescribed rigid motion are controlled by fluidic manipulation of its near wake. The body is supported by a six-degree of freedom eight-wire traverse and its motion is controlled using a dedicated servo actuator and inline load cell for each wire. The instantaneous aerodynamic forces and moments on the moving body are manipulated by controlled interactions of an azimuthal array of integrated synthetic jet actuators with the cross flow to induce localized flow attachment over the body's aft end and thereby alter the symmetry of the wake. The coupled interactions between the wake structure and the effected aerodynamic loads during prescribed time-periodic and transitory (gust like) motions are investigated with emphasis on enhancing or diminishing the loads for maneuver control, and decoupling the body's motion from its far wake.

Automatic techniques for 3D reconstruction of critical workplace body postures from range imaging data

NASA Astrophysics Data System (ADS)

Westfeld, Patrick; Maas, Hans-Gerd; Bringmann, Oliver; Gröllich, Daniel; Schmauder, Martin

2013-11-01

The paper shows techniques for the determination of structured motion parameters from range camera image sequences. The core contribution of the work presented here is the development of an integrated least squares 3D tracking approach based on amplitude and range image sequences to calculate dense 3D motion vector fields. Geometric primitives of a human body model are fitted to time series of range camera point clouds using these vector fields as additional information. Body poses and motion information for individual body parts are derived from the model fit. On the basis of these pose and motion parameters, critical body postures are detected. The primary aim of the study is to automate ergonomic studies for risk assessments regulated by law, identifying harmful movements and awkward body postures in a workplace.

Single-step methods for predicting orbital motion considering its periodic components

NASA Astrophysics Data System (ADS)

Lavrov, K. N.

1989-01-01

Modern numerical methods for integration of ordinary differential equations can provide accurate and universal solutions to celestial mechanics problems. The implicit single sequence algorithms of Everhart and multiple step computational schemes using a priori information on periodic components can be combined to construct implicit single sequence algorithms which combine their advantages. The construction and analysis of the properties of such algorithms are studied, utilizing trigonometric approximation of the solutions of differential equations containing periodic components. The algorithms require 10 percent more machine memory than the Everhart algorithms, but are twice as fast, and yield short term predictions valid for five to ten orbits with good accuracy and five to six times faster than algorithms using other methods.

Global surface temperature change analysis based on MODIS data in recent twelve years

NASA Astrophysics Data System (ADS)

Mao, K. B.; Ma, Y.; Tan, X. L.; Shen, X. Y.; Liu, G.; Li, Z. L.; Chen, J. M.; Xia, L.

2017-01-01

Global surface temperature change is one of the most important aspects in global climate change research. In this study, in order to overcome shortcomings of traditional observation methods in meteorology, a new method is proposed to calculate global mean surface temperature based on remote sensing data. We found that (1) the global mean surface temperature was close to 14.35 °C from 2001 to 2012, and the warmest and coldest surface temperatures of the global in the recent twelve years occurred in 2005 and 2008, respectively; (2) the warmest and coldest surface temperatures on the global land surface occurred in 2005 and 2001, respectively, and on the global ocean surface in 2010 and 2008, respectively; and (3) in recent twelve years, although most regions (especially the Southern Hemisphere) are warming, global warming is yet controversial because it is cooling in the central and eastern regions of Pacific Ocean, northern regions of the Atlantic Ocean, northern regions of China, Mongolia, southern regions of Russia, western regions of Canada and America, the eastern and northern regions of Australia, and the southern tip of Africa. The analysis of daily and seasonal temperature change indicates that the temperature change is mainly caused by the variation of orbit of celestial body. A big data model based on orbit position and gravitational-magmatic change of celestial body with the solar or the galactic system should be built and taken into account for climate and ecosystems change at a large spatial-temporal scale.

Evidence of an Upper Bound on the Masses of Planets and Its Implications for Giant Planet Formation

NASA Astrophysics Data System (ADS)

Schlaufman, Kevin C.

2018-01-01

Celestial bodies with a mass of M≈ 10 {M}{Jup} have been found orbiting nearby stars. It is unknown whether these objects formed like gas-giant planets through core accretion or like stars through gravitational instability. I show that objects with M≲ 4 {M}{Jup} orbit metal-rich solar-type dwarf stars, a property associated with core accretion. Objects with M≳ 10 {M}{Jup} do not share this property. This transition is coincident with a minimum in the occurrence rate of such objects, suggesting that the maximum mass of a celestial body formed through core accretion like a planet is less than 10 {M}{Jup}. Consequently, objects with M≳ 10 {M}{Jup} orbiting solar-type dwarf stars likely formed through gravitational instability and should not be thought of as planets. Theoretical models of giant planet formation in scaled minimum-mass solar nebula Shakura–Sunyaev disks with standard parameters tuned to produce giant planets predict a maximum mass nearly an order of magnitude larger. To prevent newly formed giant planets from growing larger than 10 {M}{Jup}, protoplanetary disks must therefore be significantly less viscous or of lower mass than typically assumed during the runaway gas accretion stage of giant planet formation. Either effect would act to slow the Type I/II migration of planetary embryos/giant planets and promote their survival. These inferences are insensitive to the host star mass, planet formation location, or characteristic disk dissipation time.

Globe Browsing: Contextualized Spatio-Temporal Planetary Surface Visualization.

PubMed

Bladin, Karl; Axelsson, Emil; Broberg, Erik; Emmart, Carter; Ljung, Patric; Bock, Alexander; Ynnerman, Anders

2017-08-29

Results of planetary mapping are often shared openly for use in scientific research and mission planning. In its raw format, however, the data is not accessible to non-experts due to the difficulty in grasping the context and the intricate acquisition process. We present work on tailoring and integration of multiple data processing and visualization methods to interactively contextualize geospatial surface data of celestial bodies for use in science communication. As our approach handles dynamic data sources, streamed from online repositories, we are significantly shortening the time between discovery and dissemination of data and results. We describe the image acquisition pipeline, the pre-processing steps to derive a 2.5D terrain, and a chunked level-of-detail, out-of-core rendering approach to enable interactive exploration of global maps and high-resolution digital terrain models. The results are demonstrated for three different celestial bodies. The first case addresses high-resolution map data on the surface of Mars. A second case is showing dynamic processes, such as concurrent weather conditions on Earth that require temporal datasets. As a final example we use data from the New Horizons spacecraft which acquired images during a single flyby of Pluto. We visualize the acquisition process as well as the resulting surface data. Our work has been implemented in the OpenSpace software [8], which enables interactive presentations in a range of environments such as immersive dome theaters, interactive touch tables, and virtual reality headsets.

[Body experience and motion in a biographical context: about the necessity of a body- and motion-related biographical view in gerontology].

PubMed

Abraham, Anke

2008-06-01

According to the special view of natural sciences, ageing processes are connected with measurable changes in the body. At the same time we know little about how bodily change is experienced and the subjective acceptance of the body during aging. Therefore a perspective with respect to the body has to be systematically embraced in gerontology. Knowledge perspectives and the view of the body are exemplified in theory and by analysing a case. The knowledge of experience and sense of body and motion in a person's life allows the creation of stimulating offers of growth development and health in age.

Orbit-attitude coupled motion around small bodies: Sun-synchronous orbits with Sun-tracking attitude motion

NASA Astrophysics Data System (ADS)

Kikuchi, Shota; Howell, Kathleen C.; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2017-11-01

The motion of a spacecraft in proximity to a small body is significantly perturbed due to its irregular gravity field and solar radiation pressure. In such a strongly perturbed environment, the coupling effect of the orbital and attitude motions exerts a large influence that cannot be neglected. However, natural orbit-attitude coupled dynamics around small bodies that are stationary in both orbital and attitude motions have yet to be observed. The present study therefore investigates natural coupled motion that involves both a Sun-synchronous orbit and Sun-tracking attitude motion. This orbit-attitude coupled motion enables a spacecraft to maintain its orbital geometry and attitude state with respect to the Sun without requiring active control. Therefore, the proposed method can reduce the use of an orbit and attitude control system. This paper first presents analytical conditions to achieve Sun-synchronous orbits and Sun-tracking attitude motion. These analytical solutions are then numerically propagated based on non-linear coupled orbit-attitude equations of motion. Consequently, the possibility of implementing Sun-synchronous orbits with Sun-tracking attitude motion is demonstrated.

Exploration of bounded motion near binary systems comprised of small irregular bodies

NASA Astrophysics Data System (ADS)

Chappaz, Loic; Howell, Kathleen C.

2015-10-01

To investigate the behavior of a spacecraft near a pair of irregular bodies, consider a three-body configuration (one massless). Two massive bodies, P_1 and P_2, form the primary system; each primary is modeled as a sphere or an ellipsoid. Two primary configurations are addressed: `synchronous' and `non-synchronous'. Concepts and tools similar to those applied in the circular restricted three-body problem are exploited to construct periodic trajectories for a third body in synchronous systems. In non-synchronous systems, however, the search for third body periodic orbits is complicated by several factors. The mathematical model for the third-body motion is now time-variant and the motion of P_2 is not trivial.

The Outer Space Treaty

NASA Astrophysics Data System (ADS)

Johnson, Christopher Daniel

2018-01-01

Negotiated at the United Nations and in force since 1967, the Outer Space Treaty has been ratified by over 100 countries and is the most important and foundational source of space law. The treaty, whose full title is "Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies," governs all of humankind's activities in outer space, including activities on other celestial bodies and many activities on Earth related to outer space. All space exploration and human spaceflight, planetary sciences, and commercial uses of space—such as the global telecommunications industry and the use of space technologies such as position, navigation, and timing (PNT), take place against the backdrop of the general regulatory framework established in the Outer Space Treaty. A treaty is an international legal instrument which balances rights and obligations between states, and exists as a kind of mutual contract of shared understandings, rights, and responsibilities between them. Negotiated and drafted during the Cold War era of heightened political tensions, the Outer Space Treaty is largely the product of efforts by the United States and the USSR to agree on certain minimum standards and obligations to govern their competition in "conquering" space. Additionally, the Outer Space Treaty is similar to other treaties, including treaties governing the high seas, international airspace, and the Antarctic, all of which govern the behavior of states outside of their national borders. The treaty is brief in nature and only contains 17 articles, and is not comprehensive in addressing and regulating every possible scenario. The negotiating states knew that the Outer Space Treaty could only establish certain foundational concepts such as freedom of access, state responsibility and liability, non-weaponization of space, the treatment of astronauts in distress, and the prohibition of non-appropriation of celestial bodies. Subsequent treaties were to refine these concepts, and national space legislation was to incorporate the treaty's rights and obligations at the national level. While the treaty is the cornerstone in the regulation of activities in outer space, today the emergence of new issues that were not contemplated at the time of its creation, such as small satellites and megaconstellations, satellite servicing missions, the problem of space debris and the possibility of space debris removal, and the use of lunar and asteroid resources, all stretch the coherence and continuing adequacy of the treaty, and may occasion the need for new governance frameworks.

In-motion initial alignment and positioning with INS/CNS/ODO integrated navigation system for lunar rovers

NASA Astrophysics Data System (ADS)

Lu, Jiazhen; Lei, Chaohua; Yang, Yanqiang; Liu, Ming

2017-06-01

Many countries have been paying great attention to space exploration, especially about the Moon and the Mars. Autonomous and high-accuracy navigation systems are needed for probers and rovers to accomplish missions. Inertial navigation system (INS)/celestial navigation system (CNS) based navigation system has been used widely on the lunar rovers. Initialization is a particularly important step for navigation. This paper presents an in-motion alignment and positioning method for lunar rovers by INS/CNS/odometer integrated navigation. The method can estimate not only the position and attitude errors, but also the biases of the accelerometers and gyros using the standard Kalman filter. The differences between the platform star azimuth, elevation angles and the computed star azimuth, elevation angles, and the difference between the velocity measured by odometer and the velocity measured by inertial sensors are taken as measurements. The semi-physical experiments are implemented to demonstrate that the position error can reduce to 10 m and attitude error is within 2″ during 5 min. The experiment results prove that it is an effective and attractive initialization approach for lunar rovers.

Magnetic information affects the stellar orientation of young bird migrants

NASA Astrophysics Data System (ADS)

Weindler, Peter; Wiltschko, Roswitha; Wiltschko, Wolfgang

1996-09-01

WHEN young birds leave on their first migration, they are guided by innate information about their direction of migration. It is generally assumed that this direction is represented twice, namely with respect to celestial rotation and with respect to the Earth's magnetic field1,2. The interactions between the two cue systems have been analysed by exposing hand-raised young birds during the premigratory period to cue-conflict situations, in which celestial rotation and the magnetic field provided different information. Celestial rotation altered the course with respect to the magnetic field3-7, whereas conflicting magnetic information did not seem to affect the course with respect to the stars8,9. Celestial information thus seemed to dominate over magnetic information. Here we report that the interaction between the two cue systems is far more complex than this. Celestial rotation alone seems to provide only a tendency to move away from its centre (towards geographical south), which is then modified by information from the magnetic field to establish the distinctive, population-specific migratory direction.

The Second Realization of the International Celestial Reference Frame by Very Long Baseline Interferometry

NASA Astrophysics Data System (ADS)

Fey, A. L.; Gordon, D.; Jacobs, C. S.; Ma, C.; Gaume, R. A.; Arias, E. F.; Bianco, G.; Boboltz, D. A.; Böckmann, S.; Bolotin, S.; Charlot, P.; Collioud, A.; Engelhardt, G.; Gipson, J.; Gontier, A.-M.; Heinkelmann, R.; Kurdubov, S.; Lambert, S.; Lytvyn, S.; MacMillan, D. S.; Malkin, Z.; Nothnagel, A.; Ojha, R.; Skurikhina, E.; Sokolova, J.; Souchay, J.; Sovers, O. J.; Tesmer, V.; Titov, O.; Wang, G.; Zharov, V.

2015-08-01

We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. ICRF2 contains precise positions of 3414 compact radio astronomical objects and has a positional noise floor of ∼40 μas and a directional stability of the frame axes of ∼10 μas. A set of 295 new “defining” sources was selected on the basis of positional stability and the lack of extensive intrinsic source structure. The positional stability of these 295 defining sources and their more uniform sky distribution eliminates the two greatest weaknesses of the first realization of the International Celestial Reference Frame (ICRF1). Alignment of ICRF2 with the International Celestial Reference System was made using 138 positionally stable sources common to both ICRF2 and ICRF1. The resulting ICRF2 was adopted by the International Astronomical Union as the new fundamental celestial reference frame, replacing ICRF1 as of 2010 January 1.

Warming: mechanism and latitude dependence

NASA Astrophysics Data System (ADS)

Barkin, Yury

2010-05-01

Introduction. In the work it is shown, that in present warming of climate of the Earth and in style of its display a fundamental role the mechanism of the forced swing and relative oscillations of eccentric core of the Earth and its mantle plays. Relative displacements of the centers of mass of the core and the mantle are dictated by the features of orbital motions of bodies of solar system and nonineriality of the Earth reference frame (or ot the mantle) at the motion of the Earth with respect to a baricenter of solar system and at rotation of the planet. As a result in relative translational displacements of the core and the mantle the frequencies characteristic for orbital motion of all bodies of solar system, and also their combination are shown. Methods of a space geodesy, gravimetry, geophysics, etc. unequivocally and clearly confirm phenomenon of drift of the center of mass of the Earth in define northern direction. This drift is characterized by the significant velocity in about 5 mm/yr. The unique opportunity of its explanation consists in the natural assumption of existence of the unidirectional relative displacement (drift) the center of mass of the core and the center of mass of the mantle of the Earth. And this displacement (at superfluous mass of the core in 16.7 % from the mass of full the Earth) is characterized still more significant velocity in 2.6 cm/yr and occurs on our geodynamic studies in a direction to Taimyr peninsula. The dynamic explanation to century drift for today does not exist. It is possible to note, however, that data of observations of last years, indirectly testifying that similar drifts of the centers of mass in present epoch occur on other bodies of Solar system have been obtain: the Sun, Mars, the Titan, Enceladus, the Neptune, etc. We connect with mentioned phenomena the observed secular variations of natural processes on this celestial bodies. I.e. it is possible to assume, that observable eccentric positions of the centers of mass of some bodies of solar system and attributes of secular displacements of their centers of mass are universal and testify to relative translational displacements of shells of these bodies (such as the core, the mantle and others). And it means, that there is a highly effective mechanism of an active life of planets and satellites [1, 2]. This mechanism is distinct from the tidal mechanism of gravitational interaction of deformable celestial bodies. Its action is shown, for example, even in case if the core and the mantle are considered as absolutely rigid gravitating bodies, but separated by a is viscous-elastic layer. Classics of celestial mechanics did not consider gravitational interaction and relative translational displacement of the core and the mantle of the Earth. As our studies have shown the specified new mechanism is high energetic and allows to explain many of the phenomena earlier inaccessible to understanding in various geosciences, including climatology [1] - [5]. It has been shown, that secular changes in activity of all planetary processes on the Earth are connected with a secular drift of the core of the Earth, and are controlled by the core and are reflections and displays of the core drift [5]. It is naturally, that slow climatic changes are connected with drift of the core, with induced by this drift inversion changes in an atmosphere, ocean, with thermodynamic variations of state of layer D ', with changes and variations in mantle convection and in plume activity of the Earth. The drift of the core controls a transmission of heat in the top layers of the mantle and on a surface of the Earth, organizes volcanic and seismic activity of the Earth in planetary scale. The mechanism of a warming up of layers of the mantle and cyclic inversion changes of a climate. According to a developed geodynamic model all layers of the mantle at oscillations and motions of the core under action of its gravitational attraction test wide class of inversion deformations [1]. Thus the part of energy of deformations passes in heat by virtue of dissipation properties of the mantle. Than more intensively oscillations of the core, the more amplitudes of these oscillations, the occur the specified thermal transformations more intensively. As relative displacements of the core have cyclic character, because of cyclic influences on the core-mantle system of external celestial bodies also a formation of heat flows and warmed plume materials (substances) will have also cyclic character. In particular orbital perturbations with Milankovitch's periods in 100 kyr, 41 kyr, etc. will be precisely reflected in variations of the specified thermal flows and, accordingly, a planetary climate. In it the essence of occurrence of cycles of congelations on the Earth [3] consists. If during any period of time the core behaves passively, amplitudes of its oscillations are small the thermal flows to a surface of a planet will be decrease. This geodynamic conditions corresponds to the periods of a cold snap. And on the contrary, if the core and mantle interact actively and make significant oscillations the thermal flows to a surface of a planet accrues. This geodynamic state corresponds to the periods of warming. At drift of the core to the north and its oscillations with accrueing amplitude (for example, in present period) submission of heat in the top layers of the mantle will accrue. It is warmly allocated in all layers of the mantle deformed by an attraction of the drifting and oscillating core. But a base layer is the layer D" ("kitchen of plume-tectonics"). As we know the two mechanisms work for warm redistribution into the Earth. First is a mechanism of convection. In our geodynamical model it has forced nature and is organized and controlled by gravitational action of external celestial bodies and as result has cyclical character. Second mechanism is a plume mechanism which organizes the warmed masses redistributions in higher levels of the mantle, on a bottom of ocean and on a surface of the Earth. In accordance with our geodynamical model mentioned redistribution of warmed mass also has forced character. It is organized and controlled by gravitational cyclic action of the external celestial bodies on core-mantle system. N/S inversion of the natural processes. Reliable an attribute of influence of oscillations of the core on a variation of natural processes is their property of inversion when, for example, activity of process accrues in northern hemisphere and decreases in a southern hemisphere. Such contrast secular changes in northern and southern (N/S) hemispheres have been predicted on the base of geodynamic model [1] and revealed according to observations: from gravimetry measurements of a gravity; in determination of a secular trend of a sea level, as global, and in northern and southern hemispheres; in redistribution of air masses; in geodetic measurements of changes of average radiuses of northern and southern hemispheres; in contrast changes of physical fields, for example, streams of heat, currents and circulation at ocean and an atmosphere, etc. [5]. The geodynamic mechanism [1] also unequivocally specifies, that the secular trend in global climatic characteristics of the Earth, and also inversion and asymmetric tendencies of change of a climate, in its northern and southern hemispheres in present period should be observed. The hemispherical asymmetry of global heat flows. In the paper [6] authors have shown that the mean heat flow of the Southern Hemisphere is 99.3 mW/m2, significantly higher than that of the Northern Hemisphere (74.0 mW/m2). The mantle heat loss from the Southern Hemisphere is 22.1 × 1012 W, as twice as that from the Northern Hemisphere (10.8 × 1012 W). The authors believe that this hemispherical asymmetry of global heat loss is originated by the asymmetry of geographic distribution of continents and oceans. In accordance with our geodynamical model discussed assymmetry of heat flows distribution with respect the Earth's hemispheres in first caused by eccentric position of the Earth core with respect to the mantle (displaced in present geological epoch in direction to Brasil). Of course the asymmetric distribution of heat loss is a long-term phenomenon in the geological history. But in present epoch due to drift of the core to the North we must observe some increasing of the heat flow of the Northern hemisphere and decreasing of the heat flow of the Southern hemisphere. In reality mentioned changes of heat flows are contrast (asymmetrical) and can have general tendency of increasing heat flows in both hemispheres (due to activization of relative oscillations of the core and mantle relatively polar axis). Contrast secular warming of Northern and Southern hemispheres of the Earth in present epoch. Dependence of warming from latitude. And warm flows are asymmetrically, more intensively warm is redistributed in northern hemisphere of the Earth and less intensively in a southern hemisphere. From here it follows, that the phenomenon of more intensive warming up of northern hemisphere, rather than southern in present period should be observed. Data of climatic observations (in first temperature trends for various latitude belts). More detailed analysis shows, that the phenomenon of warming in different form is shown in various latitudinal belts of the Earth. This phenomenon is more clearly shown in latitudinal belts further situated on latitude from South Pole, i.e. in high northern latitudes. Really, the trend of increase of temperature in northern hemisphere is characterized by greater rate, than a trend of temperature in a southern hemisphere. And not only trend components of temperatures increase with increasing of latitudes from southern pole to northern pole, but also amplitudes of decade fluctuations of temperature in high northern breadthes are more bigger than in southern hemisphere. Thus again it is necessary to expect a contrast and asymmetry in decade variations of temperatures in northern and southern hemispheres (smaller variations in a southern hemisphere). References [1] Barkin Yu.V. (2002) An explanation of endogenous activity of planets and satellites and its cyclisity. Isvestia sekcii nauk o Zemle Rossiiskoi akademii ectestvennykh nauk. Vyp. 9, M., VINITI, pp. 45-97. In Russian. [2] Barkin Yu.V. (2009) Moons and planets: mechanism of their life. Proceedings of International Conference 'Astronomy and World Heritage: across Time and Continents' (Kazan, 19-24 August 2009). KSU, pp. 142-161. [3] Barkin Yu.V. (2004) Dynamics of the Earth shells and variations of paleoclimate. Proceedings of Milutin Milankovitch Anniversary Symposium 'Paleoclimate and the Earth climate system' (Belgrade, Serbia, 30 August - 2 September, 2004). Belgrade, Serbian Academy of Sciences and Art, pp. 161-164. [4] Barkin Yu.V. (2007) Inversion of periodic and trend variations of climate in opposite hemispheres of the Earth and their mechanism. Proceedings of IUGG XXIV General Assembly, Perugia, Italy 2007: Earth: Our Changing Planet (Perugia, Italy, July 2-13, 2007) (P) - IAPSO, JPS001 'Interannual and Interdecadal Climate Variability', p. 1674. www. iugg2007perugia.it. [5] Barkin Yu.V. (2008) Secular polar drift of the core in present epoch: geodynamical and geophysical consequences and confirmations. General and regional problems of tectonics and geodynamics. Materials of XLI Tectonic Conference. V. 1. -M.:GEOS. p. 55-59. In Russian. [6] Yang Wang, Jiyang Wangand Zongji Ma (1998) On the asymmetric distribution of heat loss from the Earth's interior. Chinese Science Bulletin, Volume 43, Number 18 , p. 1566-1570.

Perception of biological motion from size-invariant body representations.

PubMed

Lappe, Markus; Wittinghofer, Karin; de Lussanet, Marc H E

2015-01-01

The visual recognition of action is one of the socially most important and computationally demanding capacities of the human visual system. It combines visual shape recognition with complex non-rigid motion perception. Action presented as a point-light animation is a striking visual experience for anyone who sees it for the first time. Information about the shape and posture of the human body is sparse in point-light animations, but it is essential for action recognition. In the posturo-temporal filter model of biological motion perception posture information is picked up by visual neurons tuned to the form of the human body before body motion is calculated. We tested whether point-light stimuli are processed through posture recognition of the human body form by using a typical feature of form recognition, namely size invariance. We constructed a point-light stimulus that can only be perceived through a size-invariant mechanism. This stimulus changes rapidly in size from one image to the next. It thus disrupts continuity of early visuo-spatial properties but maintains continuity of the body posture representation. Despite this massive manipulation at the visuo-spatial level, size-changing point-light figures are spontaneously recognized by naive observers, and support discrimination of human body motion.

Shaking Takete and Flowing Maluma. Non-Sense Words Are Associated with Motion Patterns

PubMed Central

Koppensteiner, Markus; Stephan, Pia; Jäschke, Johannes Paul Michael

2016-01-01

People assign the artificial words takete and kiki to spiky, angular figures and the artificial words maluma and bouba to rounded figures. We examined whether such a cross-modal correspondence could also be found for human body motion. We transferred the body movements of speakers onto two-dimensional coordinates and created animated stick-figures based on this data. Then we invited people to judge these stimuli using the words takete-maluma, bouba-kiki, and several verbal descriptors that served as measures of angularity/smoothness. In addition to this we extracted the quantity of motion, the velocity of motion and the average angle between motion vectors from the coordinate data. Judgments of takete (and kiki) were related to verbal descriptors of angularity, a high quantity of motion, high velocity and sharper angles. Judgments of maluma (or bouba) were related to smooth movements, a low velocity, a lower quantity of motion and blunter angles. A forced-choice experiment during which we presented subsets with low and high rankers on our motion measures revealed that people preferably assigned stimuli displaying fast movements with sharp angles in motion vectors to takete and stimuli displaying slow movements with blunter angles in motion vectors to maluma. Results indicated that body movements share features with information inherent in words such as takete and maluma and that people perceive the body movements of speakers on the level of changes in motion direction (e.g., body moves to the left and then back to the right). Follow-up studies are needed to clarify whether impressions of angularity and smoothness have similar communicative values across different modalities and how this affects social judgments and person perception. PMID:26939013

Rozhdenie antichnoj astrometrii %t The birth of ancient astrometry

NASA Astrophysics Data System (ADS)

Zhitomirskij, S. V.

In this article, the most probable reasons that stimulated the instrumental observations of celestial bodies are considered. In the 5th century B.C., the first stage of such observations was connected with the calendar: the measuring of the ecliptic obliquity by Oinopidus of Chios, introduction of the 19-year calendar cycle by Meton, and the discovery of inequality of the astronomic seasons by Euctemon. It is shown in the article that Euctemon defined fairly accurately time of the solstices. The theory of planet movements created in the 4th century B.C. by Eudoxus and Callipus postulated backward movements of planets along the "hippopede". This theory became a kind of challenge for the observers. In the 3rd Century B.C., Timocharis determined the equatorial coordinates of 12 stars. It is shown that those stars are connected with both the ecliptic and the equator and served possibly as points of reference in planet observations. Such observations, if they were conducted, would have shown that the planets do not follow the "hippopedes", but loop-like curves. In the same century, probably under the influence of the observational data, new theories of planet motion appeared: the heliocentric hypothesis of Aristarhus of Samos. Archimedes' geoheliocentric theory, and the theorem of similarity of excentral and epicyclical planet motion by Apollonius of Perga. In the next century, Hipparchus compiled the first Star Catalogue in history. The reason for the first mass measuring of star coordinates was the criticism of the sphere description according to Eudoxus and Aratus, because of the difference between the description of the star position and the actual observations. As to the reasons for the creation of the Star Catalogue itself, they were possibly the discovery of precession by Hipparchus, which required understanding of the character of movement of fixed stars, and the appearance of a new star in the constellation of Scorpius.

Relating Lateralization of Eye Use to Body Motion in the Avoidance Behavior of the Chameleon (Chamaeleo chameleon)

PubMed Central

Lustig, Avichai; Ketter-Katz, Hadas; Katzir, Gadi

2013-01-01

Lateralization is mostly analyzed for single traits, but seldom for two or more traits while performing a given task (e.g. object manipulation). We examined lateralization in eye use and in body motion that co-occur during avoidance behaviour of the common chameleon, Chamaeleo chameleon. A chameleon facing a moving threat smoothly repositions its body on the side of its perch distal to the threat, to minimize its visual exposure. We previously demonstrated that during the response (i) eye use and body motion were, each, lateralized at the tested group level (N = 26), (ii) in body motion, we observed two similar-sized sub-groups, one exhibiting a greater reduction in body exposure to threat approaching from the left and one – to threat approaching from the right (left- and right-biased subgroups), (iii) the left-biased sub-group exhibited weak lateralization of body exposure under binocular threat viewing and none under monocular viewing while the right-biased sub-group exhibited strong lateralization under both monocular and binocular threat viewing. In avoidance, how is eye use related to body motion at the entire group and at the sub-group levels? We demonstrate that (i) in the left-biased sub-group, eye use is not lateralized, (ii) in the right-biased sub-group, eye use is lateralized under binocular, but not monocular viewing of the threat, (iii) the dominance of the right-biased sub-group determines the lateralization of the entire group tested. We conclude that in chameleons, patterns of lateralization of visual function and body motion are inter-related at a subtle level. Presently, the patterns cannot be compared with humans' or related to the unique visual system of chameleons, with highly independent eye movements, complete optic nerve decussation and relatively few inter-hemispheric commissures. We present a model to explain the possible inter-hemispheric differences in dominance in chameleons' visual control of body motion during avoidance. PMID:23967099

Relating lateralization of eye use to body motion in the avoidance behavior of the chameleon (Chamaeleo chameleon).

PubMed

Lustig, Avichai; Ketter-Katz, Hadas; Katzir, Gadi

2013-01-01

Lateralization is mostly analyzed for single traits, but seldom for two or more traits while performing a given task (e.g. object manipulation). We examined lateralization in eye use and in body motion that co-occur during avoidance behaviour of the common chameleon, Chamaeleo chameleon. A chameleon facing a moving threat smoothly repositions its body on the side of its perch distal to the threat, to minimize its visual exposure. We previously demonstrated that during the response (i) eye use and body motion were, each, lateralized at the tested group level (N = 26), (ii) in body motion, we observed two similar-sized sub-groups, one exhibiting a greater reduction in body exposure to threat approaching from the left and one--to threat approaching from the right (left- and right-biased subgroups), (iii) the left-biased sub-group exhibited weak lateralization of body exposure under binocular threat viewing and none under monocular viewing while the right-biased sub-group exhibited strong lateralization under both monocular and binocular threat viewing. In avoidance, how is eye use related to body motion at the entire group and at the sub-group levels? We demonstrate that (i) in the left-biased sub-group, eye use is not lateralized, (ii) in the right-biased sub-group, eye use is lateralized under binocular, but not monocular viewing of the threat, (iii) the dominance of the right-biased sub-group determines the lateralization of the entire group tested. We conclude that in chameleons, patterns of lateralization of visual function and body motion are inter-related at a subtle level. Presently, the patterns cannot be compared with humans' or related to the unique visual system of chameleons, with highly independent eye movements, complete optic nerve decussation and relatively few inter-hemispheric commissures. We present a model to explain the possible inter-hemispheric differences in dominance in chameleons' visual control of body motion during avoidance.

An Interface for Specifying Rigid-Body Motions for CFD Applications

NASA Technical Reports Server (NTRS)

Murman, Scott M.; Chan, William; Aftosmis, Michael; Meakin, Robert L.; Kwak, Dochan (Technical Monitor)

2003-01-01

An interface for specifying rigid-body motions for CFD applications is presented. This interface provides a means of describing a component hierarchy in a geometric configuration, as well as the motion (prescribed or six-degree-of-freedom) associated with any component. The interface consists of a general set of datatypes, along with rules for their interaction, and is designed to be flexible in order to evolve as future needs dictate. The specification is currently implemented with an XML file format which is portable across platforms and applications. The motion specification is capable of describing general rigid body motions, and eliminates the need to write and compile new code within the application software for each dynamic configuration, allowing client software to automate dynamic simulations. The interface is integrated with a GUI tool which allows rigid body motions to be prescribed and verified interactively, promoting access to non-expert users. Illustrative examples, as well as the raw XML source of the file specifications, are included.

Dual-body magnetic helical robot for drilling and cargo delivery in human blood vessels

NASA Astrophysics Data System (ADS)

Lee, Wonseo; Jeon, Seungmun; Nam, Jaekwang; Jang, Gunhee

2015-05-01

We propose a novel dual-body magnetic helical robot (DMHR) manipulated by a magnetic navigation system. The proposed DMHR can generate helical motions to navigate in human blood vessels and to drill blood clots by an external rotating magnetic field. It can also generate release motions which are relative rotational motions between dual-bodies to release the carrying cargos to a target region by controlling the magnitude of an external magnetic field. Constraint equations were derived to selectively manipulate helical and release motions by controlling external magnetic fields. The DMHR was prototyped and various experiments were conducted to demonstrate its motions and verify its manipulation methods.

Central Configurations of the Curved N-Body Problem

NASA Astrophysics Data System (ADS)

Diacu, Florin; Stoica, Cristina; Zhu, Shuqiang

2018-06-01

We consider the N-body problem of celestial mechanics in spaces of nonzero constant curvature. Using the concept of effective potential, we define the moment of inertia for systems moving on spheres and hyperbolic spheres and show that we can recover the classical definition in the Euclidean case. After proving some criteria for the existence of relative equilibria, we find a natural way to define the concept of central configuration in curved spaces using the moment of inertia and show that our definition is formally similar to the one that governs the classical problem. We prove that, for any given point masses on spheres and hyperbolic spheres, central configurations always exist. We end with results concerning the number of central configurations that lie on the same geodesic, thus extending the celebrated theorem of Moulton to hyperbolic spheres and pointing out that it has no straightforward generalization to spheres, where the count gets complicated even for two bodies.

First Numerical Simulations of Turbulent Dynamos Driven by Libration, Precession and Tides in Triaxial Ellipsoids - An Alternative Route for Planetary Magnetism

NASA Astrophysics Data System (ADS)

Le Bars, M.; Kanuganti, S. R.; Favier, B.

2017-12-01

Most of the time, planetary dynamos are - tacitly or not - associated with thermo-solutal convection. The convective dynamo model has indeed proven successful to explain the current Earth's magnetic field. However, its results are sometimes difficult to reconcile with observational data and its validity can be questioned for several celestial bodies. For instance, the small size of the Moon and Ganymede makes it difficult to maintain a sufficient temperature gradient to sustain convection and to explain their past and present magnetic fields, respectively. The same caveat applies to the growing number of planetesimals shown to have generated magnetic fields in their early history. Finally, the energy budget of the early Earth is difficult to reconcile with a convective dynamo before the onset of inner core growth. Significant effort has thus been put into finding new routes for planetary dynamo. In particular, the rotational dynamics of planets, moons and small bodies, where their average spinning motion is periodically perturbed by the small mechanical forcings of libration, precession and/or tides, is now widely accepted as an efficient source of core turbulence. The underlying mechanism relies on a parametric instability where the inertial waves of the rotating fluid core are resonantly excited by the small forcing, leading to exponential growth and bulk filling intense motions, pumping their energy from the orbital dynamics. Dynamos driven by mechanical forcing have been suggested for the Moon, Mars, Io, the early Earth, etc. However, the real dynamo capacity of the corresponding flows has up-to-now been studied only in very limited cases, with simplified spherical/spheroidal geometries and/or overly viscous fluids. We will present here the first numerical simulations of dynamos driven by libration, precession and tides, in the triaxial ellipsoidal geometry and in the turbulent regime relevant for planetary cores. We will describe the numerical techniques required to tackle this challenge and present the first results describing the associated magnetic field in terms of amplitude, energy budget, and spatiotemporal signature. We hope to motivate others to participate in the exploration of the wide parameter space, a necessary work for addressing the variety of observed past and present magnetic fields.

Establishing a celestial VLBI reference frame. 1: Searching for VLBI sources

NASA Technical Reports Server (NTRS)

Preston, R. A.; Morabito, D. D.; Williams, J. G.; Slade, M. A.; Harris, A. W.; Finley, S. G.; Skjerve, L. J.; Tanida, L.; Spitzmesser, D. J.; Johnson, B.

1978-01-01

The Deep Space Network is currently engaged in establishing a new high-accuracy VLBI celestial reference frame. The present status of the task of finding suitable celestial radio sources for constructing this reference frame is discussed. To date, 564 VLBI sources were detected, with 166 of these lying within 10 deg of the ecliptic plane. The variation of the sky distribution of these sources with source strength is examined.

Preparing for the Next Space Race: Legislation and Policy Recommendations for Space Colonies

DTIC Science & Technology

2018-04-01

Finally, as humanity expands away from the surface of the Earth, it is important to create a free society based on the principles of the Rule of Law...with Listner, took this one step further, arguing that this means “any base or settlement on Mars would have to be free to use by anyone who can...established by a single State would deny other states free access to an area of a celestial body (namely the area where the colony is established), then

The Development of Astronomy and Emergence of Astrophysics in China

NASA Astrophysics Data System (ADS)

Ning, Xiaoyu; Sun, Xiaochun; Orchiston, Wayne; Nakamura, Tsuko

China had a long tradition of astronomy. But, like in other cultures, astronomy in ancient China was essentially positional. The study of the physical nature of celestial bodies has only been a recent development. Knowledge about astrophysics began to be transmitted to China in the middle of the nineteenth century by Western Christian missionaries. With the downfall of the Imperial Qing Dynasty and the founding of the Republic of China in 1912 astronomy began to be seen not as paraphernalia of Imperial rule but as a science with its focus on astrophysics.

KSC-07pd2400

NASA Image and Video Library

2007-09-01

KENNEDY SPACE CENTER, FLA. -- This logo represents the mission of the Dawn spacecraft. During its nearly decade-long mission, Dawn will study the asteroid Vesta and dwarf planet Ceres, celestial bodies believed to have accreted early in the history of the solar system. The mission hopes to unlock some of the mysteries of planetary formation, including the building blocks and the processes leading to their state today. The Dawn mission is managed by the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., for NASA's Science Mission Directorate in Washington, D.C.

Small solar system bodies as granular systems

NASA Astrophysics Data System (ADS)

Hestroffer, Daniel; Campo Bagatín, Adriano; Losert, Wolfgang; Opsomer, Eric; Sánchez, Paul; Scheeres, Daniel J.; Staron, Lydie; Taberlet, Nicolas; Yano, Hajime; Eggl, Siegfried; Lecomte, Charles-Edouard; Murdoch, Naomi; Radjai, Fahrang; Richardson, Derek C.; Salazar, Marcos; Schwartz, Stephen R.; Tanga, Paolo

2017-06-01

Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs are not simple monoliths, these bodies should be studied and modelled as self-gravitating granular systems in general, or as granular systems in micro-gravity environments in particular contexts. As such, the study of the geophysical characteristics of SSSBs is a multi-disciplinary effort that lies at the crossroads between Granular Mechanics, Celestial Mechanics, Soil Mechanics, Aerospace Engineering and Computer Sciences.

Solid Lubrication of Laser Deposited Carbon Nanotube Reinforced Nickel Matrix Nanocomposites Preprint

DTIC Science & Technology

2009-03-01

others [24-27], involves third body processes. Third bodies are formed by the relative motion of the two parent (first body ) materials in the...into wear particles. By separating the two first bodies , third bodies take on the chore of transmitting stresses and accommodate the relative...motion between the counterfaces. Thus friction and wear behavior is controlled by the third body processes, as opposed to the first body properties

Body Motion and Graphing.

ERIC Educational Resources Information Center

Nemirovsky, Ricardo; Tierney, Cornelia; Wright, Tracy

1998-01-01

Analyzed two children's use of a computer-based motion detector to make sense of symbolic expressions (Cartesian graphs). Found three themes: (1) tool perspectives, efforts to understand graphical responses to body motion; (2) fusion, emergent ways of talking and behaving that merge symbols and referents; and (3) graphical spaces, when changing…

A model describing vestibular detection of body sway motion.

NASA Technical Reports Server (NTRS)

Nashner, L. M.

1971-01-01

An experimental technique was developed which facilitated the formulation of a quantitative model describing vestibular detection of body sway motion in a postural response mode. All cues, except vestibular ones, which gave a subject an indication that he was beginning to sway, were eliminated using a specially designed two-degree-of-freedom platform; body sway was then induced and resulting compensatory responses at the ankle joints measured. Hybrid simulation compared the experimental results with models of the semicircular canals and utricular otolith receptors. Dynamic characteristics of the resulting canal model compared closely with characteristics of models which describe eye movement and subjective responses to body rotational motions. The average threshold level, in the postural response mode, however, was considerably lower. Analysis indicated that the otoliths probably play no role in the initial detection of body sway motion.

Eye movement instructions modulate motion illusion and body sway with Op Art.

PubMed

Kapoula, Zoï; Lang, Alexandre; Vernet, Marine; Locher, Paul

2015-01-01

Op Art generates illusory visual motion. It has been proposed that eye movements participate in such illusion. This study examined the effect of eye movement instructions (fixation vs. free exploration) on the sensation of motion as well as the body sway of subjects viewing Op Art paintings. Twenty-eight healthy adults in orthostatic stance were successively exposed to three visual stimuli consisting of one figure representing a cross (baseline condition) and two Op Art paintings providing sense of motion in depth-Bridget Riley's Movements in Squares and Akiyoshi Kitaoka's Rollers. Before their exposure to the Op Art images, participants were instructed either to fixate at the center of the image (fixation condition) or to explore the artwork (free viewing condition). Posture was measured for 30 s per condition using a body fixed sensor (accelerometer). The major finding of this study is that the two Op Art paintings induced a larger antero-posterior body sway both in terms of speed and displacement and an increased motion illusion in the free viewing condition as compared to the fixation condition. For body sway, this effect was significant for the Riley painting, while for motion illusion this effect was significant for Kitaoka's image. These results are attributed to macro-saccades presumably occurring under free viewing instructions, and most likely to the small vergence drifts during fixations following the saccades; such movements in interaction with visual properties of each image would increase either the illusory motion sensation or the antero-posterior body sway.

Clearance detector and method for motion and distance

DOEpatents

Xavier, Patrick G [Albuquerque, NM

2011-08-09

A method for correct and efficient detection of clearances between three-dimensional bodies in computer-based simulations, where one or both of the volumes is subject to translation and/or rotations. The method conservatively determines of the size of such clearances and whether there is a collision between the bodies. Given two bodies, each of which is undergoing separate motions, the method utilizes bounding-volume hierarchy representations for the two bodies and, mappings and inverse mappings for the motions of the two bodies. The method uses the representations, mappings and direction vectors to determine the directionally furthest locations of points on the convex hulls of the volumes virtually swept by the bodies and hence the clearance between the bodies, without having to calculate the convex hulls of the bodies. The method includes clearance detection for bodies comprising convex geometrical primitives and more specific techniques for bodies comprising convex polyhedra.

Circular motion of bodies of revolution

NASA Technical Reports Server (NTRS)

Kaplan, Carl

1936-01-01

The circular motion for airship-like bodies has thus far been calculated only for a prolate ellipsoid of revolution (reference 1, p.133 and reference 2). In this paper, however, the circular motion of elongated bodies of revolution more nearly resembling airships will be investigated. The results will give the effect of rotation on the pressure distribution and thus yield some information as to the stresses set up in an airship in circular flight.

Necessary conditions for tumbling in the rotational motion

NASA Astrophysics Data System (ADS)

Carrera, Danny H. Z.; Weber, Hans I.

2012-11-01

The goal of this work is the investigation of the necessary conditions for the possible existence of tumbling in rotational motion of rigid bodies. In a stable spinning satellite, tumbling may occur by sufficient strong action of external impulses, when the conical movement characteristic of the stable attitude is de-characterized. For this purpose a methodology is chosen to simplify the study of rotational motions with great amplitude, for example free bodies in space, allowing an extension of the analysis to non-conservative systems. In the case of a satellite in space, the projection of the angular velocity along the principal axes of inertia must be known, defining completely the initial conditions of motion for stability investigations. In this paper, the coordinate systems are established according to the initial condition in order to allow a simple analytical work on the equations of motion. Also it will be proposed the definition of a parameter, calling it tumbling coefficient, to measure the intensity of the tumbling and the amplitude of the motion when crossing limits of stability in the concept of Lyapunov. Tumbling in the motion of bodies in space is not possible when this coefficient is positive. Magnus Triangle representation will be used to represent the geometry of the body, establishing regions of stability/instability for possible initial conditions of motion. In the study of nonconservative systems for an oblate body, one sufficient condition will be enough to assure damped motion, and this condition is checked for a motion damped by viscous torques. This paper seeks to highlight the physical understanding of the phenomena and the influence of various parameters that are important in the process.

14 CFR 63.55 - Experience requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... satisfactory flight navigation including celestial and radio navigation and dead reckoning. A pilot who has... exclusively for practicing long-range navigation methods, with emphasis on celestial navigation and dead...

14 CFR 63.55 - Experience requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... satisfactory flight navigation including celestial and radio navigation and dead reckoning. A pilot who has... exclusively for practicing long-range navigation methods, with emphasis on celestial navigation and dead...

14 CFR 63.55 - Experience requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... satisfactory flight navigation including celestial and radio navigation and dead reckoning. A pilot who has... exclusively for practicing long-range navigation methods, with emphasis on celestial navigation and dead...

14 CFR 63.55 - Experience requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... satisfactory flight navigation including celestial and radio navigation and dead reckoning. A pilot who has... exclusively for practicing long-range navigation methods, with emphasis on celestial navigation and dead...

14 CFR 63.55 - Experience requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... satisfactory flight navigation including celestial and radio navigation and dead reckoning. A pilot who has... exclusively for practicing long-range navigation methods, with emphasis on celestial navigation and dead...

High-level context effects on spatial displacement: the effects of body orientation and language on memory

PubMed Central

Vinson, David W.; Abney, Drew H.; Dale, Rick; Matlock, Teenie

2014-01-01

Three decades of research suggests that cognitive simulation of motion is involved in the comprehension of object location, bodily configuration, and linguistic meaning. For example, the remembered location of an object associated with actual or implied motion is typically displaced in the direction of motion. In this paper, two experiments explore context effects in spatial displacement. They provide a novel approach to estimating the remembered location of an implied motion image by employing a cursor-positioning task. Both experiments examine how the remembered spatial location of a person is influenced by subtle differences in implied motion, specifically, by shifting the orientation of the person’s body to face upward or downward, and by pairing the image with motion language that differed on intentionality, fell versus jumped. The results of Experiment 1, a survey-based experiment, suggest that language and body orientation influenced vertical spatial displacement. Results of Experiment 2, a task that used Adobe Flash and Amazon Mechanical Turk, showed consistent effects of body orientation on vertical spatial displacement but no effect of language. Our findings are in line with previous work on spatial displacement that uses a cursor-positioning task with implied motion stimuli. We discuss how different ways of simulating motion can influence spatial memory. PMID:25071628

High-level context effects on spatial displacement: the effects of body orientation and language on memory.

PubMed

Vinson, David W; Abney, Drew H; Dale, Rick; Matlock, Teenie

2014-01-01

Three decades of research suggests that cognitive simulation of motion is involved in the comprehension of object location, bodily configuration, and linguistic meaning. For example, the remembered location of an object associated with actual or implied motion is typically displaced in the direction of motion. In this paper, two experiments explore context effects in spatial displacement. They provide a novel approach to estimating the remembered location of an implied motion image by employing a cursor-positioning task. Both experiments examine how the remembered spatial location of a person is influenced by subtle differences in implied motion, specifically, by shifting the orientation of the person's body to face upward or downward, and by pairing the image with motion language that differed on intentionality, fell versus jumped. The results of Experiment 1, a survey-based experiment, suggest that language and body orientation influenced vertical spatial displacement. Results of Experiment 2, a task that used Adobe Flash and Amazon Mechanical Turk, showed consistent effects of body orientation on vertical spatial displacement but no effect of language. Our findings are in line with previous work on spatial displacement that uses a cursor-positioning task with implied motion stimuli. We discuss how different ways of simulating motion can influence spatial memory.

An efficient algorithm for global periodic orbits generation near irregular-shaped asteroids

NASA Astrophysics Data System (ADS)

Shang, Haibin; Wu, Xiaoyu; Ren, Yuan; Shan, Jinjun

2017-07-01

Periodic orbits (POs) play an important role in understanding dynamical behaviors around natural celestial bodies. In this study, an efficient algorithm was presented to generate the global POs around irregular-shaped uniformly rotating asteroids. The algorithm was performed in three steps, namely global search, local refinement, and model continuation. First, a mascon model with a low number of particles and optimized mass distribution was constructed to remodel the exterior gravitational potential of the asteroid. Using this model, a multi-start differential evolution enhanced with a deflection strategy with strong global exploration and bypassing abilities was adopted. This algorithm can be regarded as a search engine to find multiple globally optimal regions in which potential POs were located. This was followed by applying a differential correction to locally refine global search solutions and generate the accurate POs in the mascon model in which an analytical Jacobian matrix was derived to improve convergence. Finally, the concept of numerical model continuation was introduced and used to convert the POs from the mascon model into a high-fidelity polyhedron model by sequentially correcting the initial states. The efficiency of the proposed algorithm was substantiated by computing the global POs around an elongated shoe-shaped asteroid 433 Eros. Various global POs with different topological structures in the configuration space were successfully located. Specifically, the proposed algorithm was generic and could be conveniently extended to explore periodic motions in other gravitational systems.

An Anatomically Constrained Model for Path Integration in the Bee Brain.

PubMed

Stone, Thomas; Webb, Barbara; Adden, Andrea; Weddig, Nicolai Ben; Honkanen, Anna; Templin, Rachel; Wcislo, William; Scimeca, Luca; Warrant, Eric; Heinze, Stanley

2017-10-23

Path integration is a widespread navigational strategy in which directional changes and distance covered are continuously integrated on an outward journey, enabling a straight-line return to home. Bees use vision for this task-a celestial-cue-based visual compass and an optic-flow-based visual odometer-but the underlying neural integration mechanisms are unknown. Using intracellular electrophysiology, we show that polarized-light-based compass neurons and optic-flow-based speed-encoding neurons converge in the central complex of the bee brain, and through block-face electron microscopy, we identify potential integrator cells. Based on plausible output targets for these cells, we propose a complete circuit for path integration and steering in the central complex, with anatomically identified neurons suggested for each processing step. The resulting model circuit is thus fully constrained biologically and provides a functional interpretation for many previously unexplained architectural features of the central complex. Moreover, we show that the receptive fields of the newly discovered speed neurons can support path integration for the holonomic motion (i.e., a ground velocity that is not precisely aligned with body orientation) typical of bee flight, a feature not captured in any previously proposed model of path integration. In a broader context, the model circuit presented provides a general mechanism for producing steering signals by comparing current and desired headings-suggesting a more basic function for central complex connectivity, from which path integration may have evolved. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determining the benefits of Vorticella cell body motion

NASA Astrophysics Data System (ADS)

Specht, Matty C.; Pepper, Rachel E.

2016-11-01

Microscopic sessile suspension feeders are single-celled organisms found in aquatic ecosystems. They live attached to underwater surfaces and create a fluid flow in order to feed on bacteria and debris. They participate in the natural degradation of contaminants in water. Understanding the fluid flow they create enhances our knowledge of their environmental impact. One type of suspension feeder, Vorticella, have been observed to vary their cell body orientation with respect to their surface, but the benefits of this motion are still unknown. We use simulations to investigate the effect of Vorticella body motion on the feeding current and the nutrient flux to the cell body to determine whether or not the motion increases nutrient consumption. We determine the nutrient flux using COMSOL Multiphysics software to solve the advection-diffusion equation with the flow given by a stokeslet model. We use a range of motions similar and dissimilar to that of live Vorticella. We find that most patterns of motion do not increase the nutrient flux, since the Vorticella feed from regions where they already have depleted the water of nutrients. However, it is possible that their motion could help the Vorticella find nutrients that are inhomogenously distributed in water.

Vector navigation in desert ants, Cataglyphis fortis: celestial compass cues are essential for the proper use of distance information.

PubMed

Sommer, Stefan; Wehner, Rüdiger

2005-10-01

Foraging desert ants navigate primarily by path integration. They continually update homing direction and distance by employing a celestial compass and an odometer. Here we address the question of whether information about travel distance is correctly used in the absence of directional information. By using linear channels that were partly covered to exclude celestial compass cues, we were able to test the distance component of the path-integration process while suppressing the directional information. Our results suggest that the path integrator cannot process the distance information accumulated by the odometer while ants are deprived of celestial compass information. Hence, during path integration directional cues are a prerequisite for the proper use of travel-distance information by ants.

Terrestrial passage theory of the moon illusion.

PubMed

Reed, C F

1984-12-01

Theories of the celestial, or moon, illusion have neglected geometric characteristics of movement along and above the surface of the earth. The illusion occurs because the characteristics of terrestrial passage are attributed to celestial passage. In terrestrial passage, the visual angle subtended by an object changes discriminably as an essentially invariant function of elevation above the horizon. In celestial passage, by contrast, change in visual angle is indiscriminable at all elevations. If a terrestrial object gains altitude, its angular subtense fails to follow the expansion projected for an orbital course: Angular diminution or constancy is equivalent to distancing. On the basis of terrestrial projections, a similar failure of celestial objects in successive elevations is also equivalent to distancing. The illusion occurs because of retinal image constancy, not--as traditionally stated--despite it.

Automatic human body modeling for vision-based motion capture system using B-spline parameterization of the silhouette

NASA Astrophysics Data System (ADS)

Jaume-i-Capó, Antoni; Varona, Javier; González-Hidalgo, Manuel; Mas, Ramon; Perales, Francisco J.

2012-02-01

Human motion capture has a wide variety of applications, and in vision-based motion capture systems a major issue is the human body model and its initialization. We present a computer vision algorithm for building a human body model skeleton in an automatic way. The algorithm is based on the analysis of the human shape. We decompose the body into its main parts by computing the curvature of a B-spline parameterization of the human contour. This algorithm has been applied in a context where the user is standing in front of a camera stereo pair. The process is completed after the user assumes a predefined initial posture so as to identify the main joints and construct the human model. Using this model, the initialization problem of a vision-based markerless motion capture system of the human body is solved.

Surrogate: A Body-Dexterous Mobile Manipulation Robot with a Tracked Base

NASA Technical Reports Server (NTRS)

Hebert, Paul (Inventor); Borders, James W. (Inventor); Hudson, Nicolas H. (Inventor); Kennedy, Brett A. (Inventor); Ma, Jeremy C. (Inventor); Bergh, Charles F. (Inventor)

2018-01-01

Robotics platforms in accordance with various embodiments of the invention can be utilized to implement highly dexterous robots capable of whole body motion. Robotics platforms in accordance with one embodiment of the invention include: a memory containing a whole body motion application; a spine, where the spine has seven degrees of freedom and comprises a spine actuator and three spine elbow joints that each include two spine joint actuators; at least one limb, where the at least one limb comprises a limb actuator and three limb elbow joints that each include two limb joint actuators; a tracked base; a connecting structure that connects the at least one limb to the spine; a second connecting structure that connects the spine to the tracked base; wherein the processor is configured by the whole body motion application to move the at least one limb and the spine to perform whole body motion.

Development of Skylab experiment T-013 crew/vehicle disturbances

NASA Technical Reports Server (NTRS)

Conway, B. A.; Woolley, C. T.; Kurzhals, P. R.; Reynolds, R. B.

1972-01-01

A Skylab experiment to determine the characteristics and effects of crew-motion disturbances was developed. The experiment will correlate data from histories of specified astronaut body motions, the disturbance forces and torques produced by these motions, and the resultant spacecraft control system response to the disturbances. Primary application of crew-motion disturbance data will be to the sizing and design of future manned spacecraft control and stabilization systems. The development of the crew/vehicle disturbances experiment is described, and a mathematical model of human body motion which may be used for analysis of a variety of man-motion activities is derived.

Motion capture based identification of the human body inertial parameters.

PubMed

Venture, Gentiane; Ayusawa, Ko; Nakamura, Yoshihiko

2008-01-01

Identification of body inertia, masses and center of mass is an important data to simulate, monitor and understand dynamics of motion, to personalize rehabilitation programs. This paper proposes an original method to identify the inertial parameters of the human body, making use of motion capture data and contact forces measurements. It allows in-vivo painless estimation and monitoring of the inertial parameters. The method is described and then obtained experimental results are presented and discussed.

Wave-induced response of a floating two-dimensional body with a moonpool

PubMed Central

Fredriksen, Arnt G.; Kristiansen, Trygve; Faltinsen, Odd M.

2015-01-01

Regular wave-induced behaviour of a floating stationary two-dimensional body with a moonpool is studied. The focus is on resonant piston-mode motion in the moonpool and rigid-body motions. Dedicated two-dimensional experiments have been performed. Two numerical hybrid methods, which have previously been applied to related problems, are further developed. Both numerical methods couple potential and viscous flow. The semi-nonlinear hybrid method uses linear free-surface and body-boundary conditions. The other one uses fully nonlinear free-surface and body-boundary conditions. The harmonic polynomial cell method solves the Laplace equation in the potential flow domain, while the finite volume method solves the Navier–Stokes equations in the viscous flow domain near the body. Results from the two codes are compared with the experimental data. The nonlinear hybrid method compares well with the data, while certain discrepancies are observed for the semi-nonlinear method. In particular, the roll motion is over-predicted by the semi-nonlinear hybrid method. Error sources in the semi-nonlinear hybrid method are discussed. The moonpool strongly affects heave motions in a frequency range around the piston-mode resonance frequency of the moonpool. No resonant water motions occur in the moonpool at the piston-mode resonance frequency. Instead large moonpool motions occur at a heave natural frequency associated with small damping near the piston-mode resonance frequency. PMID:25512594

Planetary protection - some legal questions

NASA Astrophysics Data System (ADS)

Fasan, E.

When we legally investigate the topic of Planetary Protection, we have to realise that there are primarily two very distinct parts of our juridical work: We have to study lex lata, the existing applicable Law, especially Space Law, and also lex ferenda, what should be the law. With this in mind, we have to deliberate the legal meaning of "Planetary", and of "Protection". About "Planetary": Our own Earth is the most important planet. At present only here do exist human beings, who are sensu strictu the only legal subjects. We make the law, we have to apply it, and we are to be protected as well as bound by it. Then, we have to discuss what is further meant by "Planetary": Is it planets in an astronomical sense only, the nine planets which revolve around our fixed star, namely the sun, or is it also satellites, moving around most of these planets, as our own Moon circles Earth. "The Moon and other Celestial Bodies (C.B)" are subject to Space Law, especially to International Treaties, Agreements, Resolutions of the UN etc. I propose that they and not only the planets in an strictly astronomical sense are to be protected. But I do not think that the said notion also comprises asteroids, comets, meteorites etc. although they too belong to our solar system. Our investigation comes to the result that such bodies have a different (lesser) legal quality. Also we have to ask Protection from what? From: Natural bodies - Meteorites, NEO Asteroids, Comets which could hit Earth or C.B. Artificial Objects: Space Debris threatening especially Earth and near Earth orbits. Terrestrial Life - no infection of other celestial bodies. Alien life forms which could bring about "harmful contamination" of Earth and the life, above all human life, there etc. Here, astrobiological questions have to be discussed. Special realms on C.B. which should be protected from Electronic "Noise" such as craters SAHA or Deadalus on the Moon, also taking into account the "Common Heritage" Principle. Then we have to examine: Protection where, of whom and of what: On Earth: Humans, other life forms, but also all man made things as well as air, water, soil. On Other celestial bodies: Crew of manned Space Missions, Stations on C.B., possible alien life forms, or remnants of such, water, other environment on C.B.- even if completely barren? Protection of C.B. from becoming "an area of international conflict" Finally we have to discuss overriding interests, such as deflection of Asteroids which threaten to hit Earth, then the legally permitted "Use" of C.B., also mining versus protection, and too high costs of absolutely sterile Spacecraft etc. With this we have de lege ferenda to create an order of values of protection as follows, whereby the protection of the higher category has priority over the lesser ones: 1)Human life, be it on Earth or beyond it, 2)Other terrestrial life, 3)Inanimate terrestrial environment, 4)Possible life forms or their remnants on the Moon or other C.B., 5)The natural environment of the Moon and other C.B., 6)Asteroids, Meteorites, Comets etc.

Report of the panel on earth rotation and reference frames, section 7

NASA Technical Reports Server (NTRS)

Dickey, Jean O.; Dickman, Steven R.; Eubanks, Marshall T.; Feissel, Martine; Herring, Thomas A.; Mueller, Ivan I.; Rosen, Richard D.; Schutz, Robert E.; Wahr, John M.; Wilson, Charles R.

1991-01-01

Objectives and requirements for Earth rotation and reference frame studies in the 1990s are discussed. The objectives are to observe and understand interactions of air and water with the rotational dynamics of the Earth, the effects of the Earth's crust and mantle on the dynamics and excitation of Earth rotation variations over time scales of hours to centuries, and the effects of the Earth's core on the rotational dynamics and the excitation of Earth rotation variations over time scales of a year or longer. Another objective is to establish, refine and maintain terrestrial and celestrial reference frames. Requirements include improvements in observations and analysis, improvements in celestial and terrestrial reference frames and reference frame connections, and improved observations of crustal motion and mass redistribution on the Earth.

Twist-induced guidance in coreless photonic crystal fiber: A helical channel for light.

PubMed

Beravat, Ramin; Wong, Gordon K L; Frosz, Michael H; Xi, Xiao Ming; Russell, Philip St J

2016-11-01

A century ago, Einstein proposed that gravitational forces were the result of the curvature of space-time and predicted that light rays would deflect when passing a massive celestial object. We report that twisting the periodically structured "space" within a coreless photonic crystal fiber creates a helical channel where guided modes can form despite the absence of any discernible core structure. Using a Hamiltonian optics analysis, we show that the light rays follow closed spiral or oscillatory paths within the helical channel, in close analogy with the geodesics of motion in a two-dimensional gravitational field. The mode diameter shrinks, and its refractive index rises, as the twist rate increases. The birefringence, orbital angular momentum, and dispersion of these unusual modes are explored.

[Comprehension of emotions accompanied by everyday actions: comparison of biological-motion pictures with real-person pictures].

PubMed

Higashiyama, Atsuki; Imoto, Hisato; Tsuinashi, Seiichi

2005-12-01

Forty participants viewed and interpreted videotapes that were composed of displays representing different human actions (e.g., running and washing hands) and emotions (pleasant, neutral, and unpleasant). Half the videotapes were usual movies of real persons and the other videotapes were biological motions as produced by 22 light points on a human body in otherwise total darkness. In each display, an expert or a novice played a series of large or small body actions under each emotion. We found that (1) pleasant-unpleasant feeling was well discriminated in the real-person displays and in the biological motion display of large body actions, but it was less discriminated in the biological-motion displays of small body actions, (2) actions by experts were rated to be pleasant, and (3) actions were successfully identified for the real displays of large actions by experts, but they were poorly identified for the biological-motion displays of small body actions by novices. These results suggested that the observers correctly judged the emotion of players that was represented through suitable actions.

Form and motion make independent contributions to the response to biological motion in occipitotemporal cortex.

PubMed

Thompson, James C; Baccus, Wendy

2012-01-02

Psychophysical and computational studies have provided evidence that both form and motion cues are used in the perception of biological motion. However, neuroimaging and neurophysiological studies have suggested that the neural processing of actions in temporal cortex might rely on form cues alone. Here we examined the contribution of form and motion to the spatial pattern of response to biological motion in ventral and lateral occipitotemporal cortex, using functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis (MVPA). We found that selectivity to intact versus scrambled biological motion in lateral occipitotemporal cortex was correlated with selectivity for bodies and not for motion. However, this appeared to be due to the fact that subtracting scrambled from intact biological motion removes any contribution of local motion cues. Instead, we found that form and motion made independent contributions to the spatial pattern of responses to biological motion in lateral occipitotemporal regions MT, MST, and the extrastriate body area. The motion contribution was position-dependent, and consistent with the representation of contra- and ipsilateral visual fields in MT and MST. In contrast, only form contributed to the response to biological motion in the fusiform body area, with a bias towards central versus peripheral presentation. These results indicate that the pattern of response to biological motion in ventral and lateral occipitotemporal cortex reflects the linear combination of responses to form and motion. Copyright © 2011 Elsevier Inc. All rights reserved.

Robot body self-modeling algorithm: a collision-free motion planning approach for humanoids.

PubMed

Leylavi Shoushtari, Ali

2016-01-01

Motion planning for humanoid robots is one of the critical issues due to the high redundancy and theoretical and technical considerations e.g. stability, motion feasibility and collision avoidance. The strategies which central nervous system employs to plan, signal and control the human movements are a source of inspiration to deal with the mentioned problems. Self-modeling is a concept inspired by body self-awareness in human. In this research it is integrated in an optimal motion planning framework in order to detect and avoid collision of the manipulated object with the humanoid body during performing a dynamic task. Twelve parametric functions are designed as self-models to determine the boundary of humanoid's body. Later, the boundaries which mathematically defined by the self-models are employed to calculate the safe region for box to avoid the collision with the robot. Four different objective functions are employed in motion simulation to validate the robustness of algorithm under different dynamics. The results also confirm the collision avoidance, reality and stability of the predicted motion.

Wing Rock Motion and its Flow Mechanism over a Chined-Body Configuration

NASA Astrophysics Data System (ADS)

Wang, Yankui; Li, Qian; Shi, Wei

2015-11-01

Wing rock motion is one kind of uncommanded oscillation around the body axis over the most of the aircraft at enough high angle of attack and has a strong threat to the flight safety. The purpose of this paper is to investigate the wing rock motion over a typical body-wing configuration with a chined fuselage at fixed angle of attack firstly and four kinds of wing rock motion are revealed based on the flow phenomena, namely non-oscillation, lateral deflection, limit-cycle oscillation and irregular oscillation. Simultaneously, some special relationship between the wing rock motion and the flow over the chined body configuration are discussed. In addition, the evolution of wing rock motion and its corresponding flows when the model undergoes pitching up are also given out. All the experiments have been conducted in a low-speed wind tunnel at a Reynolds number of 1.87*10E5 and angle of attack from 0deg to 65deg. National Natural Science Foundation of China(11472028) and Open fund from State Key Laboratory of Aerodynamics.

The Celestial Vault: The Magic of Astrology

NASA Astrophysics Data System (ADS)

McGaha, J.

2004-11-01

Astrology is a "Geocentric System" that supports the "Astrological Principle". This principle, that human beings and their actions are influenced by the positions of celestial objects, is not objectively supported. The "planetary gods" found in the heavens provided order to help explain the chaotic events in life on earth. Is this why many people think their horoscopes are correct, with the "stars" taking credit? Do "celestial movements" foretell the future? What is the evidence for Astrology? The historical, psychological and physical foundations of astrology will be discussed.

The Hands of the Pleiades: The Celestial Clock in the Classical Arabic Poetry of Dhū al-Rumma

NASA Astrophysics Data System (ADS)

Adams, W. B.

2011-06-01

In the desert poetry of Dhū al-Rumma (d. 117 AH/735 CE), astronomical phenomena sometimes function as familiar celestial timepieces that indicate the poetic timeframe literally and accurately. The literary, lexical, floral and astronomical analyses of a selection from this poetry illustrate the role of the Pleiades star cluster as a celestial clock and illuminate the utility of naked-eye astronomy in interpreting Arabic poetry of the early Islamic period.

The Green Bank North Celestial Cap Pulsar Survey. III. 45 New Pulsar Timing Solutions

NASA Astrophysics Data System (ADS)

Lynch, Ryan S.; Swiggum, Joseph K.; Kondratiev, Vlad I.; Kaplan, David L.; Stovall, Kevin; Fonseca, Emmanuel; Roberts, Mallory S. E.; Levin, Lina; DeCesar, Megan E.; Cui, Bingyi; Cenko, S. Bradley; Gatkine, Pradip; Archibald, Anne M.; Banaszak, Shawn; Biwer, Christopher M.; Boyles, Jason; Chawla, Pragya; Dartez, Louis P.; Day, David; Ford, Anthony J.; Flanigan, Joseph; Hessels, Jason W. T.; Hinojosa, Jesus; Jenet, Fredrick A.; Karako-Argaman, Chen; Kaspi, Victoria M.; Leake, Sean; Lunsford, Grady; Martinez, José G.; Mata, Alberto; McLaughlin, Maura A.; Noori, Hind Al; Ransom, Scott M.; Rohr, Matthew D.; Siemens, Xavier; Spiewak, Renée; Stairs, Ingrid H.; van Leeuwen, Joeri; Walker, Arielle N.; Wells, Bradley L.

2018-06-01

We provide timing solutions for 45 radio pulsars discovered by the Robert C. Byrd Green Bank Telescope. These pulsars were found in the Green Bank North Celestial Cap pulsar survey, an all-GBT-sky survey being carried out at a frequency of 350 {MHz}. We include pulsar timing data from the Green Bank Telescope and Low Frequency Array. Our sample includes five fully recycled millisecond pulsars (MSPs, three of which are in a binary system), a new relativistic double neutron star system, an intermediate-mass binary pulsar, a mode-changing pulsar, a 138 ms pulsar with a very low magnetic field, and several nulling pulsars. We have measured two post-Keplerian parameters and thus the masses of both objects in the double neutron star system. We also report a tentative companion mass measurement via Shapiro delay in a binary MSP. Two of the MSPs can be timed with high precision and have been included in pulsar timing arrays being used to search for low-frequency gravitational waves, while a third MSP is a member of the black widow class of binaries. Proper motion is measurable in five pulsars, and we provide an estimate of their space velocity. We report on an optical counterpart to a new black widow system and provide constraints on the optical counterparts to other binary MSPs. We also present a preliminary analysis of nulling pulsars in our sample. These results demonstrate the scientific return of long timing campaigns on pulsars of all types.

Eye movement instructions modulate motion illusion and body sway with Op Art

PubMed Central

Kapoula, Zoï; Lang, Alexandre; Vernet, Marine; Locher, Paul

2015-01-01

Op Art generates illusory visual motion. It has been proposed that eye movements participate in such illusion. This study examined the effect of eye movement instructions (fixation vs. free exploration) on the sensation of motion as well as the body sway of subjects viewing Op Art paintings. Twenty-eight healthy adults in orthostatic stance were successively exposed to three visual stimuli consisting of one figure representing a cross (baseline condition) and two Op Art paintings providing sense of motion in depth—Bridget Riley’s Movements in Squares and Akiyoshi Kitaoka’s Rollers. Before their exposure to the Op Art images, participants were instructed either to fixate at the center of the image (fixation condition) or to explore the artwork (free viewing condition). Posture was measured for 30 s per condition using a body fixed sensor (accelerometer). The major finding of this study is that the two Op Art paintings induced a larger antero-posterior body sway both in terms of speed and displacement and an increased motion illusion in the free viewing condition as compared to the fixation condition. For body sway, this effect was significant for the Riley painting, while for motion illusion this effect was significant for Kitaoka’s image. These results are attributed to macro-saccades presumably occurring under free viewing instructions, and most likely to the small vergence drifts during fixations following the saccades; such movements in interaction with visual properties of each image would increase either the illusory motion sensation or the antero-posterior body sway. PMID:25859197

ON THE SOURCE OF ASTROMETRIC ANOMALOUS REFRACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, M. Suzanne; McGraw, John T.; Zimmer, Peter C.

2013-03-15

More than a century ago, astronomers using transit telescopes to determine precise stellar positions were hampered by an unexplained periodic shifting of the stars they were observing. With the advent of CCD transit telescopes in the past three decades, this unexplained motion, termed 'anomalous refraction' by these early astronomers, is again being observed. Anomalous refraction is described as a low-frequency, large angular scale ({approx}2 Degree-Sign ) motion of the entire image plane with respect to the celestial coordinate system as observed and defined by astrometric catalogs. These motions, of typically several tenths of an arcsecond amplitude with timescales on themore » order of 10 minutes, are ubiquitous to ground-based drift-scan astrometric measurements regardless of location or telescopes used and have been attributed to the effect of tilting of equal-density layers of the atmosphere. The cause of this tilting has often been attributed to atmospheric gravity waves, but this cause has never been confirmed. Although theoretical models of atmospheric refraction show that atmospheric gravity waves are a plausible cause of anomalous refraction, an observational campaign specifically directed at defining this relationship provides clear evidence that anomalous refraction is not consistent with the passage of atmospheric gravity waves. The source of anomalous refraction is found to be meter-scale, slowly evolving quasi-coherent dynamical structures in the boundary layer below 60 m above ground level.« less

Centralized Networks to Generate Human Body Motions

PubMed Central

Vakulenko, Sergei; Radulescu, Ovidiu; Morozov, Ivan

2017-01-01

We consider continuous-time recurrent neural networks as dynamical models for the simulation of human body motions. These networks consist of a few centers and many satellites connected to them. The centers evolve in time as periodical oscillators with different frequencies. The center states define the satellite neurons’ states by a radial basis function (RBF) network. To simulate different motions, we adjust the parameters of the RBF networks. Our network includes a switching module that allows for turning from one motion to another. Simulations show that this model allows us to simulate complicated motions consisting of many different dynamical primitives. We also use the model for learning human body motion from markers’ trajectories. We find that center frequencies can be learned from a small number of markers and can be transferred to other markers, such that our technique seems to be capable of correcting for missing information resulting from sparse control marker settings. PMID:29240694

Centralized Networks to Generate Human Body Motions.

PubMed

Vakulenko, Sergei; Radulescu, Ovidiu; Morozov, Ivan; Weber, Andres

2017-12-14

We consider continuous-time recurrent neural networks as dynamical models for the simulation of human body motions. These networks consist of a few centers and many satellites connected to them. The centers evolve in time as periodical oscillators with different frequencies. The center states define the satellite neurons' states by a radial basis function (RBF) network. To simulate different motions, we adjust the parameters of the RBF networks. Our network includes a switching module that allows for turning from one motion to another. Simulations show that this model allows us to simulate complicated motions consisting of many different dynamical primitives. We also use the model for learning human body motion from markers' trajectories. We find that center frequencies can be learned from a small number of markers and can be transferred to other markers, such that our technique seems to be capable of correcting for missing information resulting from sparse control marker settings.

Self-motion facilitates echo-acoustic orientation in humans

PubMed Central

Wallmeier, Ludwig; Wiegrebe, Lutz

2014-01-01

The ability of blind humans to navigate complex environments through echolocation has received rapidly increasing scientific interest. However, technical limitations have precluded a formal quantification of the interplay between echolocation and self-motion. Here, we use a novel virtual echo-acoustic space technique to formally quantify the influence of self-motion on echo-acoustic orientation. We show that both the vestibular and proprioceptive components of self-motion contribute significantly to successful echo-acoustic orientation in humans: specifically, our results show that vestibular input induced by whole-body self-motion resolves orientation-dependent biases in echo-acoustic cues. Fast head motions, relative to the body, provide additional proprioceptive cues which allow subjects to effectively assess echo-acoustic space referenced against the body orientation. These psychophysical findings clearly demonstrate that human echolocation is well suited to drive precise locomotor adjustments. Our data shed new light on the sensory–motor interactions, and on possible optimization strategies underlying echolocation in humans. PMID:26064556

Lumbar joint torque estimation based on simplified motion measurement using multiple inertial sensors.

PubMed

Miyajima, Saori; Tanaka, Takayuki; Imamura, Yumeko; Kusaka, Takashi

2015-01-01

We estimate lumbar torque based on motion measurement using only three inertial sensors. First, human motion is measured by a 6-axis motion tracking device that combines a 3-axis accelerometer and a 3-axis gyroscope placed on the shank, thigh, and back. Next, the lumbar joint torque during the motion is estimated by kinematic musculoskeletal simulation. The conventional method for estimating joint torque uses full body motion data measured by an optical motion capture system. However, in this research, joint torque is estimated by using only three link angles of the body, thigh, and shank. The utility of our method was verified by experiments. We measured motion of bendung knee and waist simultaneously. As the result, we were able to estimate the lumbar joint torque from measured motion.

Every Heavenly Body When Created Will Have No Motion, Linear, Rotational and/or Vibratory Motion, Singly or in Some Combination

NASA Astrophysics Data System (ADS)

Brekke, Stewart

2010-02-01

Each galaxy, star and planet is in a state of no motion, linear, rotational and/or vibratory motion. Orbital motion is linear motion in a force field such as gravity. These motions were created in the formation of the galaxy, star or planet unless modified by external events such as colliding galaxies or impacts such as meteors. Some motions, such as rotations and vibrations may be differential such as in the cases of our sun and the Milky Way galaxy. The basic equation for each heavenly body is as follows. E = mc^2 + 1/2mv^2 + 1/2I2̂+ 1/2Kx^2 + WG+ WE+ WM. )

Precise Image-Based Motion Estimation for Autonomous Small Body Exploration

NASA Technical Reports Server (NTRS)

Johnson, Andrew Edie; Matthies, Larry H.

2000-01-01

We have developed and tested a software algorithm that enables onboard autonomous motion estimation near small bodies using descent camera imagery and laser altimetry. Through simulation and testing, we have shown that visual feature tracking can decrease uncertainty in spacecraft motion to a level that makes landing on small, irregularly shaped, bodies feasible. Possible future work will include qualification of the algorithm as a flight experiment for the Deep Space 4/Champollion comet lander mission currently under study at the Jet Propulsion Laboratory.

Thirty Years After Jack Eddy at the Big Horn Medicine Wheel

NASA Astrophysics Data System (ADS)

Merriot, Ivy

2017-01-01

In the thirty years since John (Jack) Eddy’s work on the Big Horn Medicine Wheel, attention to the astronomy of medicine wheels went from high to low, with the lowest moment occurring during the ”welcome” talk of the Oxford IX International Archaeoastronomy (ISAAC) conference in Lima, Peru in 2011 when the wall-size projected image of the Big Horn Wheel carried a thick black “X” across its face. The alignments proposed by Eddy in 1974 and by Robinson in the 1980s have been reviewed and analyzed at the Wheel on Medicine Mountain in situ under bitter cold, clear dark nights at 10,000 feet altitude. Research was conducted using naked eye skywatching, transit surveying, and a Meade Cassegraine 8” electronic telescope. Along with this “review” of 20th century research, new research was conducted Wheel causing the second decade of the 21st century to bring new physical evidence and historical information for consideration.New research at the Big Horn Medicine Wheel gives evidence that the Wheel “mirrors” the night and daytime sky by creating a sky “grid” by its design made of basement and surface stones. The Wheel’s stone design mirrors the precession of the equinoxes by showing positions of all major pole stars over the full precessional cycle. Its twenty-eight sections are useful in the same way the twenty-eight sectioned Stations of the Moon star charts were useful in ancient and historical times. This manner of dividing the sky for tracking celestial objects holds celestial markers in constant position over millennia. This occurs because the Wheel’s center represents the Sun’ ecliptic north pole. Star charts that use the ecliptic pole do not need constant mathematical computation to keep up with current declinations and right ascensions. The Wheel’s twenty-eight sectioned sky chart keeps the same Dec and RA for celestial positions for thousands of years and will more quickly alert the observer to changes due to proper motion than will our current Polaris-dependant Dec-RA system in use.

Brain-machine interfacing control of whole-body humanoid motion

PubMed Central

Bouyarmane, Karim; Vaillant, Joris; Sugimoto, Norikazu; Keith, François; Furukawa, Jun-ichiro; Morimoto, Jun

2014-01-01

We propose to tackle in this paper the problem of controlling whole-body humanoid robot behavior through non-invasive brain-machine interfacing (BMI), motivated by the perspective of mapping human motor control strategies to human-like mechanical avatar. Our solution is based on the adequate reduction of the controllable dimensionality of a high-DOF humanoid motion in line with the state-of-the-art possibilities of non-invasive BMI technologies, leaving the complement subspace part of the motion to be planned and executed by an autonomous humanoid whole-body motion planning and control framework. The results are shown in full physics-based simulation of a 36-degree-of-freedom humanoid motion controlled by a user through EEG-extracted brain signals generated with motor imagery task. PMID:25140134

The first US Naval Observatory CCD Astrograph Catalog

NASA Astrophysics Data System (ADS)

Germain, M. E.; Zacharias, N.; Urban, S. E.; Rafferty, T. J.; Holdenried, E. R.; Zacharias, M. I.; Hall, D. M.; Wycoff, G. L.; Monet, D. G.

2000-05-01

The USNO CCD Astrograph Catalog (UCAC) project is a high precision, astrometric survey of stars having R magnitudes between 7th and 16th. The positional accuracy is 20 mas for stars between 9th and 14th, and 70 mas for fainter stars. This gives a density (stars per square degree) higher than that of the Guide Star Catalog (GSC), with an improvement in positional accuracy of about a factor of ten. Observations began in January 1998 at Cerro Tololo Inter--American Observatory (CTIO) using a five-element 0.2 meter astrograph equipped with a 4k by 4k CCD. The instrument will be moved north in early 2001, and full sky coverage is expected by early 2003. A preliminary catalog (UCAC1) of positions and proper motions of 27 million stars has been constructed which is available on CD-ROM from USNO. Observations between 13 Feb 1998 and 07 Nov 1999 are included with a total of over 79,000 CCD frames covering 80% of the Southern Hemisphere. The catalog is on the International Celestial Reference System (ICRS), which is consistent with J2000. Proper motions of bright stars (V <= 12.5) were derived using a combination of ground-based astrometric catalogs, Hipparcos, and Tycho-2 positions, giving a typical error of 3 mas/yr. For the fainter stars the USNO A2.0 (Monet, 1998) was used as first epoch, with typical proper motion errors of 10 to 15 mas/yr. External comparisons with Tycho-2 and the Yale Southern Proper Motion (SPM) 2.0 data reveal systematic errors to be only on the 10 mas level.

132. STANDARD NAVAL AIR STATIONS CELESTIAL NAVIGATION, ELEVATIONS AND SECTIONS, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

132. STANDARD NAVAL AIR STATIONS CELESTIAL NAVIGATION, ELEVATIONS AND SECTIONS, BUDOCKS, OCTOBER 14, 1943. QP ACC 9689. - Quonset Point Naval Air Station, Roger Williams Way, North Kingstown, Washington County, RI

Celestial Seasonings: Astronomy and Rock Art in the American Southwest

NASA Astrophysics Data System (ADS)

Krupp, E. C.

1994-12-01

Astronomical interpretations of prehistoric rock art have played a significant part in the development of modern archaeoastronomy since 1975, when interest was renewed in the possibility that the Crab supernova explosion of 1054 A.D. was represented in rock art of the American Southwest. (This hypothesis was actually first formulated in 1955.) In the last two decades, a variety of astronomical functions for rock art have been proposed and investigated. These include representation of specific historical celestial events, symbolic representation of elements of celestial myths, star maps, markers for astronomical observing stations markers for celestially tempered shrines, images intended to invoke and exploit cosmo-magical power, seasonally significant light-and-shadow displays. Examples of astronomical connotations in prehistoric rock art from the Southwest and California illustrate the necessity of understanding the culture in any attempt to understand its astronomy.

On the dynamics of a human body model.

NASA Technical Reports Server (NTRS)

Huston, R. L.; Passerello, C. E.

1971-01-01

Equations of motion for a model of the human body are developed. Basically, the model consists of an elliptical cylinder representing the torso, together with a system of frustrums of elliptical cones representing the limbs. They are connected to the main body and each other by hinges and ball and socket joints. Vector, tensor, and matrix methods provide a systematic organization of the geometry. The equations of motion are developed from the principles of classical mechanics. The solution of these equations then provide the displacement and rotation of the main body when the external forces and relative limb motions are specified. Three simple example motions are studied to illustrate the method. The first is an analysis and comparison of simple lifting on the earth and the moon. The second is an elementary approach to underwater swimming, including both viscous and inertia effects. The third is an analysis of kicking motion and its effect upon a vertically suspended man such as a parachutist.

Lorentz Contraction, Bell's Spaceships and Rigid Body Motion in Special Relativity

ERIC Educational Resources Information Center

Franklin, Jerrold

2010-01-01

The meaning of Lorentz contraction in special relativity and its connection with Bell's spaceships parable is discussed. The motion of Bell's spaceships is then compared with the accelerated motion of a rigid body. We have tried to write this in a simple form that could be used to correct students' misconceptions due to conflicting earlier…

Kinematic analysis of basic rhythmic movements of hip-hop dance: motion characteristics common to expert dancers.

PubMed

Sato, Nahoko; Nunome, Hiroyuki; Ikegami, Yasuo

2015-02-01

In hip-hop dance contests, a procedure for evaluating performances has not been clearly defined, and objective criteria for evaluation are necessary. It is assumed that most hip-hop dance techniques have common motion characteristics by which judges determine the dancer's skill level. This study aimed to extract motion characteristics that may be linked to higher evaluations by judges. Ten expert and 12 nonexpert dancers performed basic rhythmic movements at a rate of 100 beats per minute. Their movements were captured using a motion capture system, and eight judges evaluated the performances. Four kinematic parameters, including the amplitude of the body motions and the phase delay, which indicates the phase difference between two joint angles, were calculated. The two groups showed no significant differences in terms of the amplitudes of the body motions. In contrast, the phase delay between the head motion and the other body parts' motions of expert dancers who received higher scores from the judges, which was approximately a quarter cycle, produced a loop-shaped motion of the head. It is suggested that this slight phase delay was related to the judges' evaluations and that these findings may help in constructing an objective evaluation system.

The longitudinal equations of motion of a tilt prop/rotor aircraft including the effects of wing and prop/rotor blade flexibility

NASA Technical Reports Server (NTRS)

Curtiss, H. C., Jr.

1976-01-01

The equations of motion for the longitudinal dynamics of a tilting prop/rotor aircraft are developed. The analysis represents an extension of the equations of motion. The effects of the longitudinal degrees of freedom of the body (pitch, heave and horizontal velocity) are included. The results of body freedom can be added to the equations of motion for the flexible wing propeller combination.

On population of hazardous celestial bodies in the near-Earth space

NASA Astrophysics Data System (ADS)

Shustov, B. M.; Naroenkov, S. A.; Efremova, E. V.

2017-01-01

In recent years, following the Chelyabinsk event of February 15, 2013, the lower size limit for presumably dangerous near-Earth objects has been decreased manyfold (essentially, from 140 m to 10 m). This has drawn an increased attention to the properties of the population of decameter-sized bodies, in particular, the bodies that approach the Earth from the sunward side (daytime sky). The current paper is concerned with various properties of this population. The properties of the ensemble are analyzed using both observational data from other authors and theoretical estimates obtained by cloning virtual bodies. This question is of great practical importance, as the means for detecting such bodies (for example, the SODA project) need to be developed with consideration for the requirements imposed by the population properties. We have shown that the average rate of entering near-Earth space (NES), i.e., at distances less than 1 million km from the Earth, for decameter-sized and larger bodies from the daytime sky (elongation values of entry points less than 90°) is approximately 620 objects per year for elongation angles of the detection point <90° and approximately 220 objects per year for elongation angles of the detection point <45°.

Autonomous Soft Robotic Fish Capable of Escape Maneuvers Using Fluidic Elastomer Actuators.

PubMed

Marchese, Andrew D; Onal, Cagdas D; Rus, Daniela

2014-03-01

In this work we describe an autonomous soft-bodied robot that is both self-contained and capable of rapid, continuum-body motion. We detail the design, modeling, fabrication, and control of the soft fish, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot onboard: power, actuation, processing, and control. At the core of the fish's soft body is an array of fluidic elastomer actuators. We design the fish to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum-body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared with studies on biological fish. We show that during escape responses, the soft-bodied robot has similar input-output relationships to those observed in biological fish. The major implication of this work is that we show soft robots can be both self-contained and capable of rapid body motion.

Measurement of three-dimensional posture and trajectory of lower body during standing long jumping utilizing body-mounted sensors.

PubMed

Ibata, Yuki; Kitamura, Seiji; Motoi, Kosuke; Sagawa, Koichi

2013-01-01

The measurement method of three-dimensional posture and flying trajectory of lower body during jumping motion using body-mounted wireless inertial measurement units (WIMU) is introduced. The WIMU is composed of three-dimensional (3D) accelerometer and gyroscope of two kinds with different dynamic range and one 3D geomagnetic sensor to adapt to quick movement. Three WIMUs are mounted under the chest, right thigh and right shank. Thin film pressure sensors are connected to the shank WIMU and are installed under right heel and tiptoe to distinguish the state of the body motion between grounding and jumping. Initial and final postures of trunk, thigh and shank at standing-still are obtained using gravitational acceleration and geomagnetism. The posture of body is determined using the 3D direction of each segment updated by the numerical integration of angular velocity. Flying motion is detected from pressure sensors and 3D flying trajectory is derived by the double integration of trunk acceleration applying the 3D velocity of trunk at takeoff. Standing long jump experiments are performed and experimental results show that the joint angle and flying trajectory agree with the actual motion measured by the optical motion capture system.

Pitch body orientation influences the perception of self-motion direction induced by optic flow.

PubMed

Bourrelly, A; Vercher, J-L; Bringoux, L

2010-10-04

We studied the effect of static pitch body tilts on the perception of self-motion direction induced by a visual stimulus. Subjects were seated in front of a screen on which was projected a 3D cluster of moving dots visually simulating a forward motion of the observer with upward or downward directional biases (relative to a true earth horizontal direction). The subjects were tilted at various angles relative to gravity and were asked to estimate the direction of the perceived motion (nose-up, as during take-off or nose-down, as during landing). The data showed that body orientation proportionally affected the amount of error in the reported perceived direction (by 40% of body tilt magnitude in a range of +/-20 degrees) and these errors were systematically recorded in the direction of body tilt. As a consequence, a same visual stimulus was differently interpreted depending on body orientation. While the subjects were required to perform the task in a geocentric reference frame (i.e., relative to a gravity-related direction), they were obviously influenced by egocentric references. These results suggest that the perception of self-motion is not elaborated within an exclusive reference frame (either egocentric or geocentric) but rather results from the combined influence of both. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Evaluation of Rigid-Body Motion Compensation in Cardiac Perfusion SPECT Employing Polar-Map Quantification

PubMed Central

Pretorius, P. Hendrik; Johnson, Karen L.; King, Michael A.

2016-01-01

We have recently been successful in the development and testing of rigid-body motion tracking, estimation and compensation for cardiac perfusion SPECT based on a visual tracking system (VTS). The goal of this study was to evaluate in patients the effectiveness of our rigid-body motion compensation strategy. Sixty-four patient volunteers were asked to remain motionless or execute some predefined body motion during an additional second stress perfusion acquisition. Acquisitions were performed using the standard clinical protocol with 64 projections acquired through 180 degrees. All data were reconstructed with an ordered-subsets expectation-maximization (OSEM) algorithm using 4 projections per subset and 5 iterations. All physical degradation factors were addressed (attenuation, scatter, and distance dependent resolution), while a 3-dimensional Gaussian rotator was used during reconstruction to correct for six-degree-of-freedom (6-DOF) rigid-body motion estimated by the VTS. Polar map quantification was employed to evaluate compensation techniques. In 54.7% of the uncorrected second stress studies there was a statistically significant difference in the polar maps, and in 45.3% this made a difference in the interpretation of segmental perfusion. Motion correction reduced the impact of motion such that with it 32.8 % of the polar maps were statistically significantly different, and in 14.1% this difference changed the interpretation of segmental perfusion. The improvement shown in polar map quantitation translated to visually improved uniformity of the SPECT slices. PMID:28042170

Motion-oriented 3D analysis of body measurements

NASA Astrophysics Data System (ADS)

Loercher, C.; Morlock, S.; Schenk, A.

2017-10-01

The aim of this project is to develop an ergonomically based and motion-oriented size system. New concepts are required in order to be able to deal competently with complex requirements of function-oriented workwear and personal protective equipment (PPE). Body dimensions change through movement, which are basis for motion optimized clothing development. This affects fit and ergonomic comfort. The situation has to be fundamentally researched in order to derive well-founded anthropometric body data, taking into account kinematic requirements of humans and to define functional dimensions for clothing industry. Research focus shall be on ergonomic design of workwear and PPE. There are huge differences in body forms, proportions and muscle manifestations between genders. An improved basic knowledge can be provided as a result, supporting development as well as sales of motion-oriented clothing with perfect fit for garment manufacturers.

Analysis of Timing Control Mechanism of Utterance and Body Motion Using Dialogue between Human and Communication Robot

NASA Astrophysics Data System (ADS)

Takasugi, Shoji; Yamamoto, Tomohito; Muto, Yumiko; Abe, Hiroyuki; Miyake, Yoshihiro

The purpose of this study is to clarify the effects of timing control of utterance and body motion in human-robot interaction. Our previous study has already revealed the correlation of timing of utterance and body motion in human-human communication. Here we proposed a timing control model based on our previous research and estimated its influence to realize human-like communication using a questionnaire method. The results showed that the difference of effectiveness between the communication with the timing control model and that without it was observed. In addition, elderly people evaluated the communication with timing control much higher than younger people. These results show not only the importance of timing control of utterance and body motion in human communication but also its effectiveness for realizing human-like human-robot interaction.

Experimental investigation of strain errors in stereo-digital image correlation due to camera calibration

NASA Astrophysics Data System (ADS)

Shao, Xinxing; Zhu, Feipeng; Su, Zhilong; Dai, Xiangjun; Chen, Zhenning; He, Xiaoyuan

2018-03-01

The strain errors in stereo-digital image correlation (DIC) due to camera calibration were investigated using precisely controlled numerical experiments and real experiments. Three-dimensional rigid body motion tests were conducted to examine the effects of camera calibration on the measured results. For a fully accurate calibration, rigid body motion causes negligible strain errors. However, for inaccurately calibrated camera parameters and a short working distance, rigid body motion will lead to more than 50-μɛ strain errors, which significantly affects the measurement. In practical measurements, it is impossible to obtain a fully accurate calibration; therefore, considerable attention should be focused on attempting to avoid these types of errors, especially for high-accuracy strain measurements. It is necessary to avoid large rigid body motions in both two-dimensional DIC and stereo-DIC.

Body motion for powering biomedical devices.

PubMed

Romero, Edwar; Warrington, Robert O; Neuman, Michael R

2009-01-01

Kinetic energy harvesting has been demonstrated as a useful technique for powering portable electronic devices. Body motion can be used to generate energy to power small electronic devices for biomedical applications. These scavengers can recharge batteries, extending their operation lifetime or even replace them. This paper addresses the generation of energy from human activities. An axial flux generator is presented using body motion for powering miniature biomedical devices. This generator presents a gear-shaped planar coil and a multipole NdFeB permanent magnet (PM) ring with an attached eccentric weight. The device generates energy by electromagnetic induction on the planar coil when subject to a changing magnetic flux due to the generator oscillations produced by body motion. A 1.5 cm(3) prototype has generated 3.9 microW of power while walking with the generator placed laterally on the ankle.

Non-contact and noise tolerant heart rate monitoring using microwave doppler sensor and range imagery.

PubMed

Matsunag, Daichi; Izumi, Shintaro; Okuno, Keisuke; Kawaguchi, Hiroshi; Yoshimoto, Masahiko

2015-01-01

This paper describes a non-contact and noise-tolerant heart beat monitoring system. The proposed system comprises a microwave Doppler sensor and range imagery using Microsoft Kinect™. The possible application of the proposed system is a driver health monitoring. We introduce the sensor fusion approach to minimize the heart beat detection error. The proposed algorithm can subtract a body motion artifact from Doppler sensor output using time-frequency analysis. The body motion artifact is a crucially important problem for biosignal monitoring using microwave Doppler sensor. The body motion speed is obtainable from range imagery, which has 5-mm resolution at 30-cm distance. Measurement results show that the success rate of the heart beat detection is improved about 75% on average when the Doppler wave is degraded by the body motion artifact.

Control-structure interaction/mirror motion compensation

NASA Technical Reports Server (NTRS)

Mclaren, Mark; Chu, Peter; Price, Xen

1992-01-01

Space Systems/Loral (formerly Ford Aerospace, Space Systems Division) has implemented a rigid-body Mirror Motion Compensation (MMC) scheme for the GOES-I/M spacecraft currently being built for NASA and NOAA. This has resulted in a factor of 15 reduction in pointing error due to rigid-body spacecraft motion induced by the periodic black-body calibration maneuvers required for the instruments. For GOES the spacecraft and the payload mirrors are considered as rigid bodies. The structural flexibility effects are small and are included in the total pointing budget as a separate item. This paper extends the MMC technique to include structural flexibility. For large multi-payload platforms, the structural flexibility effects can be more important in sensor pointing jitter as the result of payload motion. Sensitivity results are included to show the importance of the dynamic model fidelity.

Wave-induced response of a floating two-dimensional body with a moonpool.

PubMed

Fredriksen, Arnt G; Kristiansen, Trygve; Faltinsen, Odd M

2015-01-28

Regular wave-induced behaviour of a floating stationary two-dimensional body with a moonpool is studied. The focus is on resonant piston-mode motion in the moonpool and rigid-body motions. Dedicated two-dimensional experiments have been performed. Two numerical hybrid methods, which have previously been applied to related problems, are further developed. Both numerical methods couple potential and viscous flow. The semi-nonlinear hybrid method uses linear free-surface and body-boundary conditions. The other one uses fully nonlinear free-surface and body-boundary conditions. The harmonic polynomial cell method solves the Laplace equation in the potential flow domain, while the finite volume method solves the Navier-Stokes equations in the viscous flow domain near the body. Results from the two codes are compared with the experimental data. The nonlinear hybrid method compares well with the data, while certain discrepancies are observed for the semi-nonlinear method. In particular, the roll motion is over-predicted by the semi-nonlinear hybrid method. Error sources in the semi-nonlinear hybrid method are discussed. The moonpool strongly affects heave motions in a frequency range around the piston-mode resonance frequency of the moonpool. No resonant water motions occur in the moonpool at the piston-mode resonance frequency. Instead large moonpool motions occur at a heave natural frequency associated with small damping near the piston-mode resonance frequency. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Two Approaches in the Lunar Libration Theory: Analytical vs. Numerical Methods

NASA Astrophysics Data System (ADS)

Petrova, Natalia; Zagidullin, Arthur; Nefediev, Yurii; Kosulin, Valerii

2016-10-01

Observation of the physical libration of the Moon and the celestial bodies is one of the astronomical methods to remotely evaluate the internal structure of a celestial body without using expensive space experiments. Review of the results obtained due to the physical libration study, is presented in the report.The main emphasis is placed on the description of successful lunar laser ranging for libration determination and on the methods of simulating the physical libration. As a result, estimation of the viscoelastic and dissipative properties of the lunar body, of the lunar core parameters were done. The core's existence was confirmed by the recent reprocessing of seismic data Apollo missions. Attention is paid to the physical interpretation of the phenomenon of free libration and methods of its determination.A significant part of the report is devoted to describing the practical application of the most accurate to date the analytical tables of lunar libration built by comprehensive analytical processing of residual differences obtained when comparing the long-term series of laser observations with numerical ephemeris DE421 [1].In general, the basic outline of the report reflects the effectiveness of two approaches in the libration theory - numerical and analytical solution. It is shown that the two approaches complement each other for the study of the Moon in different aspects: numerical approach provides high accuracy of the theory necessary for adequate treatment of modern high-accurate observations and the analytic approach allows you to see the essence of the various kind manifestations in the lunar rotation, predict and interpret the new effects in observations of physical libration [2].[1] Rambaux, N., J. G. Williams, 2011, The Moon's physical librations and determination of their free modes, Celest. Mech. Dyn. Astron., 109, 85-100.[2] Petrova N., A. Zagidullin, Yu. Nefediev. Analysis of long-periodic variations of lunar libration parameters on the basis of analytical theory / // The Russian-Japanese Workshop, 20-25 October, Tokyo (Mitaka) - Mizusawa, Japan. - 2014.

South African Student Constructed Indlebe Radio Telescope

NASA Astrophysics Data System (ADS)

McGruder, Charles H.; MacPherson, Stuart; Janse Van Vuuren, Gary Peter

2017-01-01

The Indlebe Radio Telescope (IRT) is a small transit telescope with a 5 m diameter parabolic reflector working at 21 cm. It was completely constructed by South African (SA) students from the Durban University of Technology (DUT), where it is located. First light occurred on 28 July 2008, when the galactic center, Sagittarius A, was detected. As a contribution to the International Year of Astronomy in 2009, staff members in the Department of Electronic Engineering at DUT in 2006 decided to have their students create a fully functional radio telescope by 2009. The specific project aims are to provide a visible project that could generate interest in science and technology in high school students and to provide a real world system for research in radio astronomy in general and an optimization of low noise radio frequency receiver systems in particular. These aims must be understood in terms of the SA’s government interests in radio astronomy. SA is a partner in the Square Kilometer Array (SKA) project, has constructed the Karoo Array Telescope (KAT) and MeerKat, which is the largest and most sensitive radio telescope in the southern hemisphere. SA and its partners in Africa are investing in the construction of the African Very Long Baseline Interferometry Network (AVN), an array of radio telescopes throughout Africa as an extension of the existing global Very Long Baseline Interferometry Network (VLBI). These projects will allow SA to make significant contributions to astronomy and enable astronomy to contribute to the scientific education and development goals of the country. The IRT sees on a daily basis the transit of Sag A. The transit time is influenced by precession, nutation, polar motion, aberration, celestial pole offset, proper motion, length of the terrestrial day and variable ionospheric refraction. Of these eight factors six are either predictable or measureable. To date neither celestial pole offset nor variable ionospheric refraction are predicable. Currently, we are comparing the observed transit times of Sag A with the calculable predications in order to obtain information over these two factors, with a view to better understanding them.

Constraining the local variance of H {sub 0} from directional analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bengaly, C.A.P. Jr., E-mail: carlosap@on.br

We evaluate the local variance of the Hubble Constant H {sub 0} with low-z Type Ia Supernovae (SNe). Our analyses are performed using a hemispherical comparison method in order to test whether taking the bulk flow motion into account can reconcile the measurement of the Hubble Constant H {sub 0} from standard candles ( H {sub 0} = 73.8±2.4 km s{sup -1} Mpc {sup -1}) with that of the Planck's Cosmic Microwave Background data ( H {sub 0} = 67.8 ± 0.9km s{sup -1} Mpc{sup -1}). We obtain that H {sub 0} ranges from 68.9±0.5 km s{sup -1} Mpc{sup -1}more » to 71.2±0.7 km s{sup -1} Mpc{sup -1} through the celestial sphere (1 σ uncertainty), implying a Hubble Constant maximal variance of δ H {sub 0} = (2.30±0.86) km s{sup -1} Mpc{sup -1} towards the ( l,b ) = (315°,27°) direction. Interestingly, this result agrees with the bulk flow direction estimates found in the literature, as well as previous evaluations of the H {sub 0} variance due to the presence of nearby inhomogeneities. We assess the statistical significance of this result with different prescriptions of Monte Carlo simulations, obtaining moderate statistical significance, i.e., 68.7% confidence level (CL) for such variance. Furthermore, we test the hypothesis of a higher H {sub 0} value in the presence of a bulk flow velocity dipole, finding some evidence for this result which, however, cannot be claimed to be significant due to the current large uncertainty in the SNe distance modulus. Then, we conclude that the tension between different H {sub 0} determinations can plausibly be caused to the bulk flow motion of the local Universe, even though the current incompleteness of the SNe data set, both in terms of celestial coverage and distance uncertainties, does not allow a high statistical significance for these results or a definitive conclusion about this issue.« less

Star Maps, Planispheres, and Celestial Calendars : Engaging Students, Educators, and Communities with Multicultural STEM/STEAM Visual Resources

NASA Astrophysics Data System (ADS)

Lee, Annette S.; Wilson, William; Tibbetts, Jeffrey; Gawboy, Carl

2017-06-01

Aim:Designed by A. Lee, the Native Skywatchers initiative seeks to remember and revitalize indigenous star and earth knowledge, promoting the native voice as the lead voice. The overarching goal of Native Skywatchers is to communicate the knowledge that indigenous people practiced a sustainable way of living and sustainable engineering through a living and participatory relationship with the above and below, sky and earth. We aim to improve current inequities in education for native young people, to inspire increased cultural pride, and promote community wellness. We hope to inspire all participants towards a rekindling of the excitement and curiosity that causes us to look up at the sky in wonder generation after generation.Results:Presented here are several Native Skywatchers initiatives under the broad categories of: 1.) star maps, 2.) planispheres, and 3.) celestial calendars. In 2012 two indigenous star maps were created: the Ojibwe Giizhig Anung Masinaaigan-Ojibwe Sky Star Map (A. Lee, W. Wilson, C. Gawboy), and the D(L)akota star map, Makoce Wicanhpi Wowapi (A. Lee, J. Rock). More recently, a collaboration with W. Buck, science educator, at the Manitoba First Nations Resource Centre (MFNRC), in Winnipeg, Manitoba produced a third indigenous star map: Ininew Achakos Masinikan-Cree Star Map Book. Having star maps that are rooted in astronomical knowledge and cultural wisdoms has allowed communities multiple and ongoing opportunities for inclusive culture-based STEM learning. Next, planispheres were created based on the indigenous star maps. A learning and teaching hands-on tool, the planispheres, help partakers understand the patterns of motion in the night sky in addition to simply identifying the constellations. Most recently, calendar-paintings of the yearly motion of the Sun, the phases of the Moon, and the Venus-year have all been added to the growing list of Native Skywatchers resources. Working collaboratively with regional schools, educators, museums, liaisons, and communities this work offers a solid example of how community based participatory programs can be the spark for effective culture-based STEM learning.

A Conventional Mean Pole

NASA Astrophysics Data System (ADS)

Stamatakos, N. G.; McCarthy, D. D.

2016-12-01

A CONVENTIONAL MEAN POLE PATH The gradual drift of the pole associated with the rotational axis of the Earth in a terrestrial reference frame is characterized by the motion of a "mean pole." The IERS Conventions (2010) does not provide a formal definition of such a "mean pole." In its glossary it defines the terminology "mean pole" in the celestial frame by using the definition "the position on the celestial sphere towards which the Earth's axis points at a particular epoch, with the oscillations due to precession-nutation removed." The need for a terrestrial mean pole is mentioned in Section 7.1.4 of the IERS Conventions, which outlines the procedure to account for the variation in terrestrial site coordinates caused by the pole tide. It states, that an estimate of the wander of the mean pole to within about 10 milliarc-seconds is needed to ensure that the geopotential field is aligned to the long term mean pole. Historically the angular coordinates of this "mean pole" were calculated by averaging the observed angular coordinates of the rotational pole over six years, the beat period of the annual and approximately 14-month Chandler motions of the rotational pole. The IERS Conventions (2010) realization of the mean pole is composed of a cubic fit of the polar coordinates valid over 1976-2010 and a linear model for extrapolation after 2010.0. Further it notes that in the future, the IERS conventional mean pole will be revised as needed with sufficient advance notice. However, this document leaves open the formal definition of a conventional terrestrial mean pole, the spectral frequency content to be expected in such a definition and a procedure to be used to realize the coordinates of the path for users. Background is provided regarding past realizations of a "mean pole," and the requirements for a realization of a mean pole path are reviewed. Possible definitions and potential mathematical models to provide mean pole coordinates in the future are outlined. In addition, the authors hope that this poster will serve to open a discussion, which will identify geodesy disciplines that require a mean pole and what type of definition would be suitable to their needs.

Method and System for Physiologically Modulating Videogames and Simulations which Use Gesture and Body Image Sensing Control Input Devices

NASA Technical Reports Server (NTRS)

Pope, Alan T. (Inventor); Stephens, Chad L. (Inventor); Habowski, Tyler (Inventor)

2017-01-01

Method for physiologically modulating videogames and simulations includes utilizing input from a motion-sensing video game system and input from a physiological signal acquisition device. The inputs from the physiological signal sensors are utilized to change the response of a user's avatar to inputs from the motion-sensing sensors. The motion-sensing system comprises a 3D sensor system having full-body 3D motion capture of a user's body. This arrangement encourages health-enhancing physiological self-regulation skills or therapeutic amplification of healthful physiological characteristics. The system provides increased motivation for users to utilize biofeedback as may be desired for treatment of various conditions.

Rigid Body Motion in Stereo 3D Simulation

ERIC Educational Resources Information Center

Zabunov, Svetoslav

2010-01-01

This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between…