MONTE: the next generation of mission design and navigation software

Evans, Scott; Taber, William; Drain, Theodore; Smith, Jonathon; Wu, Hsi-Cheng; Guevara, Michelle; Sunseri, Richard F.; Evans, James R.

doi:10.1007/s12567-017-0171-7

Cited by 115 publications

(66 citation statements)

References 4 publications

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“…The Doppler data have been compressed at 60 s and analyzed with MONTE, the JPL orbit determination code (Evans, et al, 2016). Cassini's dynamical model includes the gravitational effect in a relativistic context due to the Solar System planets including Saturn and its satellites.…”

Section: Discussionmentioning

confidence: 99%

Titan's gravity field and interior structure after Cassini

Durante

Hemingway

Racioppa

et al. 2019

Icarus

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Since its arrival at Saturn in 2004, Cassini performed nine flybys devoted to the determination of Titan's gravity field and its tidal variations. Here we present an updated gravity solution based on the final data set collected during the gravity-dedicated passes, before Cassini's plunge into Saturn's atmosphere. The data set includes an additional flyby (T110, March 2015, primarily devoted to imaging Titan's north polar lakes) carried out with the low-gain antenna. This flyby was particularly valuable because the closest approach occurred at a high latitude (75°N), over an area not previously sampled. Previously published gravity results (Iess, et al., 2012) indicated that Titan is subject to large eccentricity tides in response to the time varying perturbing potential exerted by Saturn. The magnitude of the response quadrupole field, expressed in the tidal Love number k 2 , was used to infer the existence of an internal ocean. The new gravity field determination provides an improved estimate of k 2 of about 0.62, accurate to a level of a few percent. The value is higher than the simplest models of Titan suggest and the interpretation is unclear; possibilities include a high density ocean (as high as 1300 kg/m 3), a partially viscous response of the deeper region, or a dynamic contribution to the tidal response. The new solution includes higher degree and order harmonic coefficients (up to 5) and offers an improved map of gravity anomalies. The geoid is poorly correlated with the topography, implying strong compensation. In addition, the updated geoid and its associated uncertainty could be used to refine the gravity-altimetry correlation analysis and for improved interpretation of radar altimetric data.

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Section: Discussionmentioning

confidence: 99%

Titan's gravity field and interior structure after Cassini

Durante

Hemingway

Racioppa

et al. 2019

Icarus

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“…The data were analyzed using JPL's orbit determination program MONTE (Evans et al, 2018), currently used for the operations of several NASA deep space missions and for past radio science data analysis (e.g. Iess et al, 2018;Iess et al 2019).…”

Section: Data Selection and Calibrationmentioning

confidence: 99%

The gravity field and interior structure of Dione

Zannoni,

Hemingway,

Gomez Casajus

et al. 2020

Icarus

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During its mission in the Saturn system, Cassini performed five close flybys of Dione. During three of them, radio tracking data were collected during the closest approach, allowing estimation of the full degree-2 gravity field by precise spacecraft orbit determination.The gravity field of Dione is dominated by J2 and C22, for which our best estimates are J2 x 10 6 = 1496 ± 11 and C22 x 10 6 = 364.8 ± 1.8 (unnormalized coefficients, 1-σ uncertainty). Their ratio is J2/C22 = 4.102 ± 0.044, showing a significative departure (about 17-σ) from the theoretical value of 10/3, predicted for a relaxed body in slow, synchronous rotation around a planet. Therefore, it is not possible to retrieve the moment of inertia directly from the measured gravitational field.The interior structure of Dione is investigated by a combined analysis of its gravity and topography, which exhibits an even larger deviation from hydrostatic equilibrium, suggesting some degree of compensation. The gravity of Dione is far from the expectation for an undifferentiated hydrostatic body, so we built a series of three-layer models, and considered both Airy and Pratt compensation mechanisms. The interpretation is non-unique, but Dione's excess topography may suggest some degree of Airy-type isostasy, meaning that the outer ice shell is underlain by a higher density, lower viscosity layer, such as a subsurface liquid water ocean. The data permit a broad range of possibilities, but the best fitting models tend towards large shell thicknesses and small ocean thicknesses.

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“…We used the Mission Operations and Navigation Toolkit Environment (MONTE) software [ Evans et al , ] for orbit determination and parameter estimation. MONTE is developed and maintained by NASA's Jet Propulsion Laboratory (JPL).…”

Section: Force and Measurement Modelsmentioning

confidence: 99%

Mercury's gravity, tides, and spin from MESSENGER radio science data

Verma

Margot

2016

JGR Planets

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We analyze radio tracking data obtained during 1311 orbits of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in the period March 2011 to April 2014. A least squares minimization of the residuals between observed and computed values of two‐way range and Doppler allows us to solve for a model describing Mercury's gravity, tidal response, and spin state. We use a spherical harmonic representation of the gravity field to degree and order 40 and report error bars corresponding to 10 times the formal uncertainties of the fit. Our estimate of the product of Mercury's mass and the gravitational constant, GM = (22031.87404 ± 9×10−4) km3 s−2, is in excellent agreement with published results. Our solution for the geophysically important second‐degree coefficients ( trueC̄2,0=−2.25100×10−5±1.3×10−9, trueC̄2,2=1.24973×10−5±1.2×10−9) confirms previous estimates to better than 0.4% and, therefore, inferences about Mercury's moment of inertia and interior structure. Our estimate of the tidal Love number k2 = 0.464 ± 0.023 indicates that Mercury's mantle may be hotter and weaker than previously thought. Our spin state solution suggests that gravity‐based estimates of Mercury's spin axis orientation are marginally consistent with previous measurements of the orientation of the crust.

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MONTE: the next generation of mission design and navigation software

Cited by 115 publications

References 4 publications

Titan's gravity field and interior structure after Cassini

Titan's gravity field and interior structure after Cassini

The gravity field and interior structure of Dione

Mercury's gravity, tides, and spin from MESSENGER radio science data

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