Flight path design issues for the TOPEX mission

Frautnick, J. C.; Cutting, E.

doi:10.2514/6.1983-197

Cited by 3 publications

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“…In Table III, a comparison between the numerical simulations in this study with simulation results in Frautnick's (1983) study is performed. The obtained results show important role of frozen conditions in maintaining low-altitude orbital elements' stability against zonal harmonic perturbations.…”

Section: Numerical Simulation and Resultsmentioning

confidence: 97%

Spacecraft OMM reduction using stable frozen orbit conditions

Soleymani

Toloei

2015

Aircraft Eng & Aerospace Tech

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Purpose -The purpose of this research was to analyze application effects of the stable frozen orbit conditions in the spacecraft Orbital Maintenance Maneuver (OMM) reduction. Design/methodology/approach -One challenge in implementing these motions is maintaining the relations as it experiences orbital perturbations (zonal harmonics), most notably due to the non-spherical Earth. A natural phenomenon exists called a frozen orbit, for which the orbital elements: argument of perigee () and eccentricity (e) remain virtually fixed over extended periods of time. Findings -Simulation results show that, using stable frozen orbit condition results in considerable propellant saving, decreased OMM, increase of accuracy position errors and thus performance improvement of the spacecraft for orbiter mission is preferable. So, from among three proposed theories, the Brouwer-Hori theory has provided better accuracy and more stable conditions in the frozen orbit. Practical implications -Simulation algorithm has been achieved to solve this problem by extracting and combining the equations that govern the frozen conditions with the tangential forces (⌬V) equations for orbit correction. Originality/value -In all studies with content of harmonic perturbation effects on the spacecraft motion dynamics, main goal is to obtain a solution for optimization of the operation process, so that overshadowed mission costs. The case studies about this aim, mostly to the trajectory parameters optimization by considering the vehicle orbital conditions under various control methods are formed. While in this regards, the intrinsic properties of stable Earth orbits and using them effectively is less than to analyse the problems is considered.

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Section: Numerical Simulation and Resultsmentioning

confidence: 97%

Spacecraft OMM reduction using stable frozen orbit conditions

Soleymani

Toloei

2015

Aircraft Eng & Aerospace Tech

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On the choice of orbits for an altimetric satellite to study ocean circulation and tides

Stewart²,

et al. 1987

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The choice of an orbit for satellite altimetric studies of the ocean's circulation and tides requires an understanding of the orbital characteristics that influence the accuracy of the satellite's measurements of sea level and the temporal and spatial distribution of the measurements. Three orbital parameters determine the temporal and spatial sampling characteristics of the satellite: the orbital altitude, the inclination of the orbit, and the repetition period. The eccentricity of the chosen orbit should be less than 0.001 to minimize altimeter errors caused by uncertainty in determining the time of each altimeter measurement and to maintain the rate of height variation over the oceans within the limits of the altimeter tracker. The choice of the satellite's orbital altitude is constrained by the influences of atmospheric drag and errors in models of the gravity field, which decrease with height, and the required complexity of the altimeter (e.g., the power and/or antenna size required) and the effect on satellite systems of radiation from Earth's radiation belts, which increase with height. The choice of inclination is constrained by a desire to measure sea level over all the ocean, by the requirement that the acute angle between intersections of the subsatellite track be as large as possible, and by the time phasing of the repeat of the satellite's ground track as a function of inclination, which determines the aliased frequencies of the measurements of the oceanic tides. The choice of repetition period is constrained by tradeoffs between temporal and spatial coverage and by the aliasing of tidal constituents. Combining the above constraints leads to a set of orbits in a narrow range of altitude and inclination, called here the "Topex/Poseidon window." This window extends from 1100 to 1500 km altitude and 62 ø to 66 ø inclination for a 10-day repeat period and consists of three subwindows following lines of equal orbit plane precession. There are four choices of orbits within these subwindows that overtly the planned calibration sites at Bermuda and Dakar. These are at 64. 80 ø and 1335 km, 62.01 ø and 1252 km, 65.84 ø and 1255 km, and 62.69 ø and 1173 km. These choices have a minimum separation between the aliased frequencies of the eight largest diurnal and semidiurnal tides of one cycle per 4.71 years, one cycle per 4.86 years, one cycle per 4.87 years, and one cycle per 4.27 years, respectively. Thus there will be less than one cycle separation over the nominal (3 years) mission.Of these four choices, the first at 64.8 ø and 1335 km is preferable, because it is less sensitive to error in estimating the upcoming solar cycle (which will be a maximum during the mission), and because it is more nearly centered in terms of inclination than the other choices. For other calibration sites, other choices would have to be made. Additional work, beyond the scope of this paper, will also be necessary to determine if the Topex/Poseidon mission requires a frozen orbit (i.e., an orbit for which there are no long-term va...

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Analysis and application of frozen orbits for the TOPEX mission

Smith

1986

Astrodynamics Conference

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Flight path design issues for the TOPEX mission

Cited by 3 publications

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Spacecraft OMM reduction using stable frozen orbit conditions

Spacecraft OMM reduction using stable frozen orbit conditions

On the choice of orbits for an altimetric satellite to study ocean circulation and tides

Analysis and application of frozen orbits for the TOPEX mission

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