The rotation of LAGEOS

Bertotti, B.; Iess, L.

doi:10.1029/90jb01949

Cited by 60 publications

(49 citation statements)

References 22 publications

(14 reference statements)

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“…According to Landau and Lifshitz [1984] and Bertotti and Iess [1991], the magnetic torque of an axial symmetrical conductor rotating along its axis of symmetry with angular velocity W can be expressed as…”

Section: Lageos Spin Axis Modelmentioning

confidence: 99%

“…A few years later he inverted this line of reasoning and solved for the orientation of the spin axis by matching his model predictions for the along-track acceleration to the estimated empirical values, concluding that an almost fixed spin axis orientation could explain the data well [Rubincam, 1990]. A significant step further was made by Bertotti and Iess [1991], who applied the theory describing the motion of a conductor in a magnetic field to LAGEOS-I. This theory, known as the BI theory since [Farinella et al, 1996], is the basis of all subsequent studies, including this one.…”

Section: Introductionmentioning

confidence: 99%

“…This theory, known as the BI theory since [Farinella et al, 1996], is the basis of all subsequent studies, including this one. A very important conclusion in Bertotti and Iess [1991] was the suggestion of an alternative solution for the initial orientation of the spin axis: the so-called Southern Solution, which is related to the solution of Rubincam (called the Northern Solution since then) by a simple spatial inversion. In 1996, Farinella et al [1996 further developed the BI theory by correcting some errors which appeared in Bertotti and Iess [1991].…”

Section: Introductionmentioning

confidence: 99%

“…A very important conclusion in Bertotti and Iess [1991] was the suggestion of an alternative solution for the initial orientation of the spin axis: the so-called Southern Solution, which is related to the solution of Rubincam (called the Northern Solution since then) by a simple spatial inversion. In 1996, Farinella et al [1996 further developed the BI theory by correcting some errors which appeared in Bertotti and Iess [1991]. Their results confirmed the validity of the Southern Solution, and an orientation model was obtained for both LAGEOS-I and LAGEOS-II, based on perturbations caused by magnetic and gravitational torques.…”

Section: Introductionmentioning

confidence: 99%

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Spin axis behavior of the LAGEOS satellites

Andres

Noomen

Bianco³

et al. 2004

J. Geophys. Res.

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[1] The satellites LAGEOS-I and LAGEOS-II are essential for the scientific study of various (geo)physical phenomena, such as geocenter motion and absolute scale. The high quality of such science products strongly depends on the absolute quality of the SLR observations and that of the orbit description. Therefore all accelerations experienced by the spacecraft need to be modeled as accurately as possible, the thermal radiation forces being one of them. Traditionally, this is done by estimating so-called empirical accelerations. However, the rotational dynamics of LAGEOS-I in particular no longer allows such a simple approach: a full modeling of the spin behavior, the temperature distribution over the spacecraft surface and the resulting net force prove necessary to achieve the best results. As a first step, a new model, Lageos Spin Axis Model (LOSSAM) has been developed. It is unique in its combination of analytical theory and empirical observations. Its mathematics is taken after previous investigators, although flaws have been corrected. LOSSAM describes the full spin behavior of LOSSAM based on the following phenomena: (1) the geomagnetic field, (2) the Earth's gravity field, (3) the satellite center of pressure offset, and (4) the effective difference in reflectivity between the satellite hemispheres. Its accuracy has been demonstrated by an improvement of about a 50% in the RMS residual of the Yarkovsky-Schach effect signal (as shown by Lucchesi et al. [2004]). Such a high-quality model for rotational behavior is indispensable for a proper force modeling, and hence also for the quality of typical LAGEOS science products.

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Section: Lageos Spin Axis Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin axis behavior of the LAGEOS satellites

Andres

Noomen

Bianco³

et al. 2004

J. Geophys. Res.

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“…These patterns are, however, insufficient because the accurate knowledge of the position of the LAGEOS satellite's rotation axis is necessary (Bertotti & Iess, 1991). Rubincam et al (1997) (29) and (31), and added for each date.…”

Section: Figura 6 -Componentes Radial Transversal E Normal Da Acelermentioning

confidence: 99%

Thermal re-emission effects on the LAGEOS I satellite versus spin axis orientation

Duha¹,

Afonso²,

Ferreira³

2001

Rev. Bras. Geof.

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Since 1976 when the LAGEOS I satellite was launched, the evolution of thermal re-emission effects has been observed and modeled. The effect of sun and earth heating has been analyzed separately and thermal models have been able, almost completely, to explain most of the residuals observed. However, after more than fifteen years of reasonable agreement between theory and observations, unexpected peaks in the along-track perturbations appeared and brought new attention to the problem of thermal force modeling. The efforts to explain these unexpected residual effects have produced interesting works such as the redefinition of the average coefficient of reflectivity (pressure of direct solar radiation), the Yarkovsky-Schach effect (thermal re-emission due to the solar heating), and the effect of asymmetrical reflection at the satellite's surface. Despite the lack of detailed data about the spin axis evolution, changes in the spin axis orientation have been also analyzed, however, none of these effects or corrections seems able to explain the observations. We present in this paper a unified thermal model that includes, simultaneously, the effects of sun and earth heating. The close connection between energy source coordinates (sun and earth) and the periodicity of satellite rotation and translation leads to complex sinusoidal functions that can explain the sudden peaks of maximum and minimum. We show that the residuals observed for LAGEOS I satellite can be predicted and explained by the thermal model presented and we also extend the analysis to a set of test-satellites with different spin axis inclinations concluding that the most stable spin axis configuration is the 90°-03°: spin axis perpendicular to the satellite orbital plane related to the Earth (90°) and spin axis lying on the orbital plane related to the Sun (03°). This configuration is desirable from the point of view of orbit stability because it minimizes the thermal re-emission effects and does not present great peaks of maximum after some years of orbit.Key words: Thermal Re-emission; Unified Model; LAGEOS. EFEITOS DE RE-EMISSÃO TÉRMICA NO SATÉLITE LAGEOS I VERSUS ORIENTAÇÃO DO EIXO DE ROTAÇÃO -Desde 1976, quando o satélite LAGEOS I foi lançado, efeitos de re-emissão térmica tem sido observados e modelados. Os efeitos de aquecimento devidos ao Sol e a Terra têm sido analisados separadamente e os modelos térmicos existentes têm revelado-se aptos a explicar, quase completamente, a maioria dos resíduos observados. No entanto, após mais de quinze anos de razoável concordância entre a teoria e as observações surgem picos inesperados nas perturbações transversais despertando renovada atenção ao problema da modelagem de forças térmicas. Os esforços para explicar esses efeitos residuais inesperados têm resultado em trabalhos interessantes assim como a redefinição do coeficiente de refletividade médio (pressão da radiação solar direta), o efeito

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Fundamental Physics with the LAGEOS Satellites

Peron

2015

Gravity: Where Do We Stand?

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The rotation of LAGEOS

Cited by 60 publications

References 22 publications

Spin axis behavior of the LAGEOS satellites

Spin axis behavior of the LAGEOS satellites

Thermal re-emission effects on the LAGEOS I satellite versus spin axis orientation

Fundamental Physics with the LAGEOS Satellites

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