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Results for “ORBIT PERTURBATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

On disk-planet interactions and orbital eccentricities

While Lindblad resonances both within and without a perturber's orbit excite its eccentricity, the present study of the eccentricity evolution due to the density wave interaction between a planetesimal and a Keplerian disk notes that coronation resonances in these regions lose their eccentricity damping effectiveness if the object is embedded in a continuous disk without a gap. Attention is given to another class of Lindblad resonances which, under these conditions, operates on disk material coorbiting with the perturber; these resonances thereby become the most important source of eccentricity damping. A model problem indicates that eccentricity ultimately undergoes decay.

Ward, William R.↗
NASA NTRS1992

Atmospheric gravitational influence on geodetic satellite orbits - Starlette analysis

The atmosphere is constantly in motion. The changing gravitational force due to the air mass movement will slightly perturb the orbit of a satellite. As the instrument accuracy for geodetic satellites improves, failure to model this perturbation can result in significant systematic errors in the orbit determination. The latter, in turn, will degrade the Earth's gravity solutions. A direct modeling technique to analyze the atmospheric gravitational influence on geodetic satellite is developed. We use the global surface pressure data from the ECMWF Initial Analysis Database to compute the gravitational force due to atmospheric perturbation exerted on given satellite as a function of time during selected orbital arcs. Satellite Laser Ranging (SLR) tracking data for selected Starlette (altitude 900 km) orbital arcs are used to test the computed force model. Although only a slight reduction in the rms residuals is observed when the atmospheric gravitational perturbation is included in the force model for data reduction of the SLR data, significant improvement is obtained in the predictability of the satellite orbit. Comprehensive studies involving more definitive test criteria and more refined models are still needed.

Chao, B. F.↗
NASA NTRS1976

Spherical harmonic representation of the gravity field of Mars using a short-arc technique

Planetary gravity fields are primarily determined from Doppler tracking of orbiting spacecraft which are typically in high eccentricity orbits. Thus, the non-central gravitational components perturb the orbit primarily in the vicinity of periapsis. To find a computationally efficient technique and to reduce the influence of unmodeled forces on the spacecraft, an analysis has been performed of the effectiveness of processing only data in the vicinity of periapsis using multiple short arcs. Mariner 9 data are processed for the study, using 1, 2, 3 and 4 hour arcs and estimating gravity fields from 4th through 7th degree. The resulting gravity fields are inter-compared and also compared with previously published results.

Daniels, E. F.↗
NASA NTRS1979

Long period perturbations of earth satellite orbits

All the equations involved in extending the PS phi solution to include the long periodic and second order secular effects of the zonal harmonics are presented. Topics covered include DSphi elements and relations for their conconical transformation into the PS phi elements; the solution algorithm based on the Von Zeipel method; and the elimination of long periodic terms and analytical integration of primed variables. The equations were entered into the ASOP program, checked out, and verified. Comparisons with numerical integrations show the long period theory to be accurate within several meters after 800 revolutions.

Wang, K. C.↗
NASA NTRS2015

Orbit Stability of OSIRIS-REx in the Vicinity of Bennu Using a High-Fidelity Solar Radiation Model

The OSIRIS-REx mission (Origins Spectral Interpretation Resource Identification Security Regolith EXPlorer) is an asteroid sample return mission to Bennu (RQ36) that is scheduled to launch in 2016. The planned science operations precluding the small retrieval involve operations in terminator orbits (orbit plane is perpendicular to the sun). Over longer durations the solar radiation pressure (SRP) perturbs the orbit causing it to precess. Our work involves: modeling high fidelity SRP model to capture the perturbations during attitude changes; design a stable orbit from the high fidelity models to analyze the stability over time.

Williams, Trevor↗
NASA NTRS1974

Relative motion of orbiting particles under the influence of perturbing forces. Volume 1: Summary

The relative motion for orbiting vehicles, under the influence of various perturbing forces, has been studied to determine what influence these inputs, and others, can have. The analytical tasks are discribed in general terms; the force types considered, are outlined modelled and simulated, and the capabilities of the computer programs which have evolved in support of this work are denoted.

Eades, J. B., Jr.↗
NASA NTRS2017

The Design of the Reference Orbit for NISAR, the NASA-ISRO Synthetic Aperture Radar Mission

The NISAR mission plans to use a 12-day-repeating sun-synchronous orbit for repeat-pass interferometry at multiple time scales using SAR data. For the interferometry to work the radar measurements must be made from within a critical baseline, which happens if all of the orbits are maintained to be within a fixed tube around a reference orbit. This paper describes the choice of dynamical models used in defining such a reference orbit, the perturbative effects of dynamics not considered in the repeat orbit, and the process of designing the orbit to repeat. We also describe our method for sharing the repeat orbit among multiple mission participants who use different models and software.

Hatch, Sara J.↗
NASA NTRS2017

The Design of the Reference Orbit for NISAR, the NASA-ISRO Synthetic Aperture Radar Mission

The NISAR mission plans to use a 12-day-repeating sun-synchronous orbit for repeat-pass interferometry at multiple time scales using SAR data. For the interferometry to work the radar measurements must be made from within a critical baseline, which happens if all of the orbits are maintained to be within a fixed tube around a reference orbit. This paper describes the choice of dynamical models used in defining such a reference orbit, the perturbative effects of dynamics not considered in the repeat orbit, and the process of designing the orbit to repeat. We also describe our method for sharing the repeat orbit among multiple mission participants who use different models and software.

Hatch, Sara J.↗
NASA NTRS1984

Determining asteroid masses from perturbations on Mars

The orbit of Mars is perturbed more than 5 m, a value compatible with the accuracy of the Viking Lander ranging data, by about three dozen asteroids. In addition to larger asteroids throughout the belt, significant perturbations of long period are generated by smaller objects near commensurabilities with Mars. The largest periodic terms induced by 1 Ceres and 2 Pallas have amplitudes of 0.8 and 0.2 km, respectively, both with 10-year periods. Due to a near commensurability, 4 Vesta causes a 5-km, 52-year term. While the Viking ranges will yield significant mass determinations for the largest three asteroids, and some of the smaller bodies should be detectable, it will be difficult to separate the smaller bodies with useful accuracies. Accurate discrimination must await range data from future missions to Mars or other bodies in the neighborhood of the asteroid belt. The Viking ranges can also yield improved masses for the outer planets (except Pluto), an application which is being exploited by groups analyzing these data. Uncertainties in the asteroid masses limit the ultimate accuracy of the Viking determinations of both the long time scale motion of the system of the inner four planets with respect to an inertial frame and the rate of change of the gravitational constant.

Williams, J. G.↗