The Dawn Gravity Investigation at Vesta and Ceres

Konopliv, A. S.; Asmar, S. W.; Bills, B. G.; Mastrodemos, N.; Park, R. S.; Raymond, C. A.; Smith, David E.; Zuber, M. T.

doi:10.1007/s11214-011-9794-8

Cited by 64 publications

(30 citation statements)

References 71 publications

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“…These data are used in the gravity investigation to obtain the mass of the bodies orbited and the distribution of that mass (42). The cameras on-board the spacecraft are also used to perform optical navigation that complements the radiometric tracking.…”

Section: Methodsmentioning

confidence: 99%

Dawn arrives at Ceres: Exploration of a small, volatile-rich world

Russell

Raymond

Ammannito

et al. 2016

Science

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198

124

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On 6 March 2015, Dawn arrived at Ceres to find a dark, desiccated surface punctuated by small, bright areas. Parts of Ceres’ surface are heavily cratered, but the largest expected craters are absent. Ceres appears gravitationally relaxed at only the longest wavelengths, implying a mechanically strong lithosphere with a weaker deep interior. Ceres’ dry exterior displays hydroxylated silicates, including ammoniated clays of endogenous origin. The possibility of abundant volatiles at depth is supported by geomorphologic features such as flat crater floors with pits, lobate flows of materials, and a singular mountain that appears to be an extrusive cryovolcanic dome. On one occasion, Ceres temporarily interacted with the solar wind, producing a bow shock accelerating electrons to energies of tens of kilovolts.

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Section: Methodsmentioning

confidence: 99%

Dawn arrives at Ceres: Exploration of a small, volatile-rich world

Russell

Raymond

Ammannito

et al. 2016

Science

Self Cite

198

124

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“…The Dawn spacecraft has been orbiting Ceres since March 2015 and will determine the shape, topography, and gravity field of Ceres with unprecedented accuracy (Raymond et al 2011;Konopliv et al 2011). Like for many other bodies, it is expected that the comparison of the measurements against the computed hydrostatic solution will reveal non-hydrostatic anomalies.…”

Section: Discussionmentioning

confidence: 99%

Third-order development of shape, gravity, and moment of inertia for highly flattened celestial bodies. Application to Ceres

Rambaux

Chambat

Castillo‐Rogez

2015

A&A

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Context. We investigate the hydrostatic shape and gravitational potential coefficients of self-gravitating and rotating bodies large enough to have undergone internal differentiation and chemical stratification. Quantifying these properties under the assumption of hydrostatic equilibrium forms the basis for interpreting shape and gravity data in terms of interior structure and infer deviations from hydrostaticity that can bring information on the thermal and chemical history of the objects. Aims. The main purpose is to show the importance of developing the reference hydrostatic shape for relatively fast rotating bodies up to third order to reach an accuracy of a few tens of meters. This paper especially focuses on Ceres, for which high-resolution shape data are being obtained by the Dawn spacecraft, with a projected accuracy better than 200 m/pixel. Methods. To improve the accuracy on the determination of geodetic parameters, we numerically integrated Clairaut's equations of rotational equilibrium expanded up to third order in a small parameter m, the geodetic parameter.Results. Previous studies of Ceres have been based on shape models developed to first order. However, we show that the first-order theory underestimates (a − c) (where a and c are the equatorial and polar radii) by 1.8 km, which leads to underestimating the extent of mass concentration and is insufficient to interpret the upcoming observations by Dawn space mission. Instead, by using the third-order theory, we obtain an accuracy of 25 meters that is better than the accuracy expected from Dawn. Then, we derive the following geodetical quantities: flattening and other shape parameters, gravitational potential coefficients, and moments of inertia, by using the Ceres models constrained by observations obtained with the Hubble Space Telescope and ground-based adaptive optics telescopes. The difference in equatorial and polar radii for a large parametric space of interior models is investigated, and the large (a − c) corresponds to a model with a low density contrast. Conclusions. This type of modeling will also prove instrumental to infer non-hydrostatic contributions to Ceres' shape that are to be measured by Dawn.

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“…The approach for obtaining and processing X-band radio science data to measure the gravity field has high heritage from many JPL missions and benefits from the very similar experience of the Dawn gravity science investigation, incorporating several members of the Dawn gravity science team at MIT and JPL [9].…”

Section: Science Instrumentsmentioning

confidence: 99%

Psyche Science Operations Concept: Maximize Reuse to Minimize Risk

Polanskey

Elkins-Tanton

Jaumann

et al. 2018

2018 SpaceOps Conference

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and the Psyche TeamIn January 2017, the Psyche mission concept was selected as the 14th in NASA's Discovery Program. The mission would explore the unique metallic asteroid, (16) Psyche, believed to be the exposed core of a larger planetesimal that was stripped of its rocky mantle through multiple collisions during the early formation of the solar system. While the scientific goals of the Psyche mission concept are novel, the approach to science and mission operations is adapted from the earlier Dawn mission. Psyche shares two major attributes with Dawn, also Discovery class, that makes Dawn an obvious template. Both missions orbit massive bodies in the main asteroid belt with previously unmeasured gravity fields, and both utilize solar electric propulsion. The Dawn operations concept was developed over many years, coming to completion while the spacecraft was en route to the first target, protoplanet (4) Vesta. Because these concepts were demonstrated in flight, the Psyche team was able to reuse them to realize a plan of similar fidelity during the first phase of proposal development. Understanding the operations concept to this level of detail during mission formulation reduces the implementation risk of the Psyche mission.

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The Dawn Gravity Investigation at Vesta and Ceres

Cited by 64 publications

References 71 publications

Dawn arrives at Ceres: Exploration of a small, volatile-rich world

Dawn arrives at Ceres: Exploration of a small, volatile-rich world

Third-order development of shape, gravity, and moment of inertia for highly flattened celestial bodies. Application to Ceres

Psyche Science Operations Concept: Maximize Reuse to Minimize Risk

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