Study of Spacecraft Orbital Motion in the Upper Atmosphere Using Averaging PDF Download

Author: Miin-Nan Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 354

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Author: D. G. King-Hele
Publisher:
ISBN:
Category :
Languages : en
Pages : 18

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The rotation of the upper atmosphere subjects a satellite to an aerodynamic force normal to the orbit, which has the effect of slightly reducing the inclination of the orbit to the equator. The average rotational speed of the upper atmosphere at heights a little above that of perigee can be evaluated from the observed changes in orbital inclination. Since the change in inclination is small (less than 0.1 degree), the values generally have to be averaged over several months, and they can also be regarded as applying over latitudes up to about half the inclination, the effects being strongest at the equator. Recent results reviewed in the report confirm a previous finding that the upper atmosphere at heights of 200 to 350 km rotates on average faster than the Earth, and that the average rate of rotation increases with height from about 1.1 rev/day at 200 km to nearly 1.4 rev/day at 350 km. However, it appears that the rotation rate decreases above 350 km, to about 1.0 rev/day at 420 km and 0.7 rev/day at 500 km. (Author).

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723453878
Category :
Languages : en
Pages : 104

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Upper Atmosphere Research Satellite flight data from the first 737 days after launch (September 1991) was used to investigate spacecraft disturbances and responses. The investigation included two in-flight dynamics experiments (approximately three orbits each). Orbital and configuration influences on spacecraft dynamic response were also examined. Orbital influences were due to temperature variation from crossing the Earth's terminator and variation of the solar incident energy as the orbit precessed. During the terminator crossing, the rapid ambient temperature change caused the spacecraft's two flexible appendages to experience thermal elastic bending (thermal snap). The resulting response was dependent upon the orientation of the solar array and the solar incident energy. Orbital influences were also caused by on-board and environmental disturbances and spacecraft configuration changes resulting in dynamic responses which were repeated each orbit. Configuration influences were due to solar array rotation changing spacecraft modal properties. The investigation quantified the spacecraft dynamic response produced by the solar array and high gain antenna harmonic drive disturbances. The solar array's harmonic drive output resonated two solar array modes. Friction in the solar array gear drive provided sufficient energy dissipation which prevented the solar panels from resonating catastrophically; however, the solar array vibration amplitude was excessively large. The resulting vibration had a latitude-specific pattern. Woodard, Stanley E. Langley Research Center UPPER ATMOSPHERE RESEARCH SATELLITE (UARS); DYNAMIC RESPONSE; SPACECRAFT CONFIGURATIONS; SOLAR ARRAYS; VIBRATION EFFECTS; SPACECRAFT ORBITS; SOLAR ENERGY; ELASTIC BENDING; TEMPERATURE EFFECTS; ANTENNA COMPONENTS; FRICTION; ENERGY DISSIPATION; SATELLITE ATTITUDE CONTROL; ORBITAL MECHANICS; APPENDAGES; ROTATION; MECHANICAL DRIVES...

Author:
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ISBN:
Category :
Languages : en
Pages : 0

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Atmospheric density modeling has long been one of the greatest uncertainties in the dynamics of low Earth satellite orbits. Accurate density calculations are required to provide meaningful estimates of the atmospheric drag perturbing satellite motion. These effects increase with lower altitude orbits and also with higher effective area and lower mass satellites. Both of these conditions are usually met by the new class of small satellites being developed around the world as low-cost ventures into space. Early atmospheric models consisted of simple exponential functions with scale height factors that allowed the user to estimate a constant density at a given altitude. From these approaches and estimated density conditions, standard atmospheres were developed that were meant to represent the average conditions at any given point in time for a particular altitude. However, it was soon obvious that the atmosphere was far too dynamic to be adequately represented by static approaches. The 1990s brought a new approach to improving atmospheric density modeling. Dynamic Calibration of the Atmosphere (DCA) involves estimating density corrections to a given atmospheric density model based upon the observed motion of satellites. The goal of atmospheric density dynamics research is to understand and characterize the dynamic nature of the extreme upper atmosphere and develop improved orbital prediction algorithms based upon this new understanding. Many indicators suggest that the extreme upper atmosphere is far more dynamic than what is accounted for in atmospheric density models used in orbit propagation. This paper explores the impact these dynamics have on the motion of satellites. Simulations show that unmodeled atmospheric density dynamics can greatly impact the orbit determination process and add kilometers of error to orbit predictions. (10 figures, 8 refs.).

Author: Howard D. Curtis
Publisher: Elsevier
ISBN: 0080887848
Category : Technology & Engineering
Languages : en
Pages : 740

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Orbital Mechanics for Engineering Students, Second Edition, provides an introduction to the basic concepts of space mechanics. These include vector kinematics in three dimensions; Newton's laws of motion and gravitation; relative motion; the vector-based solution of the classical two-body problem; derivation of Kepler's equations; orbits in three dimensions; preliminary orbit determination; and orbital maneuvers. The book also covers relative motion and the two-impulse rendezvous problem; interplanetary mission design using patched conics; rigid-body dynamics used to characterize the attitude of a space vehicle; satellite attitude dynamics; and the characteristics and design of multi-stage launch vehicles. Each chapter begins with an outline of key concepts and concludes with problems that are based on the material covered. This text is written for undergraduates who are studying orbital mechanics for the first time and have completed courses in physics, dynamics, and mathematics, including differential equations and applied linear algebra. Graduate students, researchers, and experienced practitioners will also find useful review materials in the book. - NEW: Reorganized and improved discusions of coordinate systems, new discussion on perturbations and quarternions - NEW: Increased coverage of attitude dynamics, including new Matlab algorithms and examples in chapter 10 - New examples and homework problems

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 556

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Author: Daniel J. Scheeres
Publisher: Springer
ISBN: 3642032567
Category : Technology & Engineering
Languages : en
Pages : 396

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The investigation of minor solar system bodies, such as comets and asteroids, using spacecraft requires an understanding of orbital motion in strongly perturbed environments. The solutions to a wide range of complex and challenging problems in this field are reviewed in this comprehensive and authoritative work.

Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1080

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Author: United States. Congress
Publisher:
ISBN:
Category : Law
Languages : en
Pages : 1356

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 730

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