Final manoeuvre from highly elliptical orbit towards Lagrangian points

2018 ◽  
Author(s):  
Irina Kovalenko ◽  
Natan Eysmont
Keyword(s):  
Elliptical Orbit ◽  
Lagrangian Points

scholarly journals Orbit Decomposition Method for Rotordynamic Coefficients Identification of Annular Seals

2021 ◽  
Vol 11 (9) ◽  
pp. 4237
Author(s):  
Mingjie Zhang ◽  
Jiangang Yang ◽  
Wanfu Zhang ◽  
Qianlei Gu
Keyword(s):  
Circular Orbit ◽  
Present Method ◽  
Decomposition Method ◽  
Parameter Analysis ◽  
Elliptical Orbit ◽  
Computational Time ◽  
Solution Technique ◽  
Rotordynamic Coefficients ◽  
Cfd Method ◽  
Annular Seals

The elliptical orbit whirl model is widely used to identify the frequency-dependent rotordynamic coefficients of annular seals. The existing solution technique of an elliptical orbit whirl model is the transient computational fluid dynamics (CFD) method. Its computational time is very long. For rapid computation, this paper proposes the orbit decomposition method. The elliptical whirl orbit is decomposed into the forward and backward circular whirl orbits. Under small perturbation circumstances, the fluid-induced forces of the elliptical orbit model can be obtained by the linear superposition of the fluid-induced forces arising from the two decomposed circular orbit models. Due to that the fluid-induced forces of circular orbit, the model can be calculated with the steady CFD method, and the transient computations can be replaced with steady ones when calculating the elliptical orbit whirl model. The computational time is significantly reduced. To validate the present method, its rotordynamic results are compared with those of the transient CFD method and experimental data. Comparisons show that the present method can accurately calculate the rotordynamic coefficients. Elliptical orbit parameter analysis reveals that the present method is valid when the whirl amplitude is less than 20% of seal clearance. The effect of ellipticity on rotordynamic coefficients can be ignored.

On the Deployment of a Tether from an Elliptical Orbit

1998 ◽  
Vol 46 (2) ◽  
pp. 119-133 ◽  
Author(s):  
M. Ruiz ◽  
J. Peláez
Keyword(s):  
Elliptical Orbit

Elliptical Orbit of Asteroid 1986 QE1

1989 ◽  
Vol 12 ◽  
pp. 21-24
Author(s):  
H. Debehogne ◽  
L.E. Machado ◽  
S. Vaz ◽  
E.R. Netto
Keyword(s):  
Photographic Plate ◽  
Elliptical Orbit ◽  
Orbital Elements ◽  
European Southern Observatory ◽  
Geocentric Distance ◽  
Before And After

We present the orbital elements of asteroid QE1 (pro visional designation) identified in august 26, 1986, on a photographic plate obtained at the GPO telescope of the European Southern Observatory (ESO), La Silla, Chile, as well as the positions (AR and Dec) referred to 1950.0. Residues (0 - C) of the position in AR and Dec of the asteroid are given, both before and after applying variation in the geocentric distance.

scholarly journals The habitable zone of Kepler-16: impact of binarity and climate models

2018 ◽  
Vol 18 (1) ◽  
pp. 79-89 ◽  
Author(s):  
S. Y. Moorman ◽  
B. L. Quarles ◽  
Zh. Wang ◽  
M. Cuntz
Keyword(s):  
Binary System ◽  
Main Sequence ◽  
Climate Models ◽  
Main Sequence Star ◽  
Habitable Zone ◽  
Lagrangian Points ◽  
The Earth ◽  
Stable Solutions

AbstractWe continue to investigate the binary system Kepler-16, consisting of a K-type main-sequence star, a red dwarf and a circumbinary Saturnian planet. As part of our study, we describe the system's habitable zone based on different climate models. We also report on stability investigations for possible Earth-mass Trojans while expanding a previous study by B. L. Quarles and collaborators given in 2012. For the climate models, we carefully consider the relevance of the system's parameters. Furthermore, we pursue new stability simulations for the Earth-mass objects starting along the orbit of Kepler-16b. The eccentricity distribution as obtained prefers values close to circular, whereas the inclination distribution remains flat. The stable solutions are distributed near the co-orbital Lagrangian points, thus enhancing the plausibility that Earth-mass Trojans might be able to exist in the Kepler-16(AB) system.

scholarly journals Spatial and Temporal Sampling of Polar Regions from Two-Satellite System on Molniya Orbit

2011 ◽  
Vol 28 (8) ◽  
pp. 977-992 ◽  
Author(s):  
Alexander P. Trishchenko ◽  
Louis Garand
Keyword(s):  
Temporal Resolution ◽  
Arctic Region ◽  
Satellite System ◽  
Elliptical Orbit ◽  
High Temporal Resolution ◽  
Polar Regions ◽  
Temporal Sampling ◽  
Continuous Coverage ◽  
Depth Analysis

Abstract There has been a significant increase of interest in the building of a comprehensive Arctic observing system in recent years to properly and timely track the environmental and climate processes in this vast region. In this regard, a satellite observing system on highly elliptical orbit (HEO) with 12-h period (Molniya type) is of particular interest, because it enables continuous coverage of the entire Arctic region (58°–90°N) from a constellation of two satellites. Canada is currently proposing to operate such a constellation by 2017. Extending the pioneering study of S. Q. Kidder and T. H. Vonder Haar, this paper presents in-depth analysis of spatiotemporal sampling properties of the imagery from this system. This paper also discusses challenges and advantages of this orbit for various applications that require high temporal resolution and angular sampling.

Stochastic multi-satellite maneuvering with constraints in an elliptical orbit

2021 ◽  
Author(s):  
Shawn Priore ◽  
Abraham Vinod ◽  
Vignesh Sivaramakrishnan ◽  
Christopher Petersen ◽  
Meeko Oishi
Keyword(s):  
Elliptical Orbit

Acceptance

2021 ◽  
pp. 186-222
Author(s):  
Clive Gamble
Keyword(s):  
Stone Tools ◽  
Elliptical Orbit ◽  
Ice Age ◽  
Racial Groups ◽  
Stone Age ◽  
Evolutionary Pathway ◽  
Career Changes ◽  
The Earth ◽  
New Space ◽  
Guided Tour

By the end of the decade the time revolution was a done deal. Moulin-Quignon still reverberated, but in 1865 Lubbock produced the first guided tour of the Old Stone Age, in which he accused Lyell of plagiarism. In Pre-Historic Times he filled the new space of deep history with stone tools to show an evolutionary pathway from St Acheul to the Neolithic monuments of Avebury and Stonehenge. Tracing history back was matched by the anthropologist Edward Tylor, who traced it up. Both men were interested in the evolution of racial groups and accounting for the world’s hunters and gatherers. In a typically upbeat assessment, Lubbock saw the lesson of the past as providing hope for the future. Victorian ‘savages’ at the uttermost ends of the earth had not degenerated from a civilized state. They had the potential to evolve, as his ancestors in Europe had done. Unwritten history was making universal history possible. The decade saw deaths and career changes. Prestwich largely abandoned the time revolution, married Falconer’s niece, Grace McCall, and became an Oxford professor. Falconer and Boucher de Perthes died, while Lubbock entered Parliament in 1870. Prestwich’s fixed notion of a single ice age was challenged by James Croll, who painstakingly worked out the changes in the elliptical orbit of the Earth, and from these proposed multiple ice ages. As a bookend to the decade Evans published his fact-rich volume on ancient stone implements. The path of deep history was now set in stone.

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