A Global Solution for the Gravity Field, Rotation, Landmarks, and Ephemeris of Eros

Konopliv, Alexander S.; Miller, James; Owen, W. M.; Yeomans, Donald K.; Giorgini, Jon D.; Garmier, Romain; Barriot, Jean‐Pierre

doi:10.1006/icar.2002.6975

Cited by 80 publications

(43 citation statements)

References 15 publications

(24 reference statements)

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“…Both the laser communication terminal and the RSE will enhance the accuracy of orbit determination and will support a first ever in-situ GRavity Experiment (GRE) on a binary system (as already done with RSE for planets, e.g., Rosenblatt and Dehant (2010) and for single asteroids, e.g., Konopliv et al (2002)). The RSE will also help to accurately measure the expected orbital change of the system.…”

Section: Measurements By Aimmentioning

confidence: 98%

Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

Michel

Cheng

Küppers

et al. 2016

Advances in Space Research

103

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The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to test the kinetic impactor technique to deflect an asteroid. The European Asteroid Impact Mission (AIM) is set to rendezvous with the asteroid system to fully characterise the smaller of the two binary components a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near-Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions.The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Having direct information on the surface and internal properties of small asteroids will allow us to understand how the vaious processes they undergo work and transform these small bodies as well as, for this particular case, how a binary system forms. Making these measurements from up close and comparing them with ground-based data from telescopes will also allow us to calibrate remote observations and improve our data interpretation of other systems. With DART, thanks to the characterization of the target by AIM, the mission will be the first fully documented impact experiment at asteroid scale, which will include the characterization of the target's properties and the outcome of the impact. AIDA will thus offer a great opportunity to test and refine our understanding and models at the actual scale of an asteroid, and to check whether the current extrapolations of material strength from laboratory-scale targets to the scale of AIDA's target are valid. Moreover, it will offer a first check of the validity of the kinetic impactor concept to deflect a small body and lead to improved efficiency for future kinetic impactor designs. This paper focuses on the science return of AIM, the current knowledge of its target from ground-based observations, and the instrumentation planned to get the necessary data.

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Section: Measurements By Aimmentioning

confidence: 98%

Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

Michel

Cheng

Küppers

et al. 2016

Advances in Space Research

103

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“…Current best estimates are summarized in Table 1. Vesta's mass has been determined from perturbations of Vesta by other asteroids (Michalak 2000;Baer and Chesley 2008;Kuzmanoski et al 2010), by the perturbation of Mars' orbit by Vesta (Standish 2001;Pitjeva 2005;Konopliv et al 2006Konopliv et al , 2011aFienga et al 2009), and by perturbation of the orbit of asteroid 433 Eros by Vesta using the range data from the Near Earth Asteroid Rendezvous (NEAR) spacecraft (Konopliv et al 2002(Konopliv et al , 2011a. Vesta is the second most massive asteroid, though its mass is only 28% of Ceres (Pitjeva 2005); currently Vesta's mass has an uncertainty of ∼2%.…”

Section: Mass Shape/volume and Bulk Densitymentioning

confidence: 99%

Origin, Internal Structure and Evolution of 4 Vesta

et al. 2011

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Asteroid 4 Vesta is the only preserved intact example of a large, differentiated protoplanet like those believed to be the building blocks of terrestrial planet accretion. Vesta accreted rapidly from the solar nebula in the inner asteroid belt and likely melted due to heat released due to the decay of 26 Al. Analyses of meteorites from the howardite-eucritediogenite (HED) suite, which have been both spectroscopically and dynamically linked to Vesta, lead to a model of the asteroid with a basaltic crust that overlies a depleted peridotitic mantle and an iron core. Vesta's crust may become more mafic with depth and might have been intruded by plutons arising from mantle melting. Constraints on the asteroid's moments of inertia from the long-wavelength gravity field, pole position and rotation, informed by bulk composition estimates, allow tradeoffs between mantle density and core size; cores of up to half the planetary radius can be consistent with plausible mantle compositions. The asteroid's present surface is expected to consist of widespread volcanic terrain, modified extensively by impacts that exposed the underlying crust or possibly the mantle. Hemispheric heterogeneity has been observed by poorly resolved imaging of the surface that suggests the possibility of a physiographic dichotomy as occurs on other terrestrial planets. Vesta might have had an early magma ocean but details of the early thermal structure are far from clear owing to model uncertainties and paradoxical observations from the HEDs. Petrological analysis of the eucrites coupled with thermal evolution modeling recognizes two possible mechanisms of silicate-metal differentiation leading to the formation of the basaltic M.T. Zuber et al.achondrites: equilibrium partial melting or crystallization of residual liquid from the cooling magma ocean. A firmer understanding the plethora of complex physical and chemical processes that contribute to melting and crystallization will ultimately be required to distinguish among these possibilities. The most prominent physiographic feature on Vesta is the massive south polar basin, whose formation likely re-oriented the body axis of the asteroid's rotation. The large impact represents the likely major mechanism of ejection of fragments that became the HEDs. Observations from the Dawn mission hold the promise of revolutionizing our understanding of 4 Vesta, and by extension, the nature of collisional, melting and differentiation processes in the nascent solar system. Large Asteroids as Planetary EmbryosThe largest asteroids are central to understanding nascent planetary evolution, and among these 4 Vesta plays a unique role in the reconstruction of the physical and chemical processes that comprise collectively terrestrial planet accretion. Vesta is alone among the largest asteroids in having a basaltic crust (McCord et al. 1970) indicative of silicate volcanic and/or plutonic processes (Binzel et al. 2003). Observations of surface spectra (McCord et al. 1970;Binzel and Xu 1993) in concert with information on ...

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“…Recovering a spacecraft's trajectory with modern day Structure from Motion approaches allows for further investigation for perturbations to accelerations due to variation in the strength of gravity. Understanding the variations of these forces, as well as developing a map, help to derive various models on the interior structure of the target planetary body or asteroid [1,4].Classical approaches for recovering the strength of a gravitational field study the motion of a satellite by tracking its position with Earth based telescopes. The basic principle behind this approach was developed in the field of satellite geodesy with the specific goal to define a highly accurate map of Earth's gravitational field.…”

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confidence: 99%

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confidence: 99%

An Image Based Approach to Recovering the Gravitational Field of Asteroids

Melim¹,

Dellaert²

2014

Proceedings of the British Machine Vision Conference 2014

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(a) (b) Figure 1: (a) Gravitational field strength with harmonic coefficients of degree n and order m. (b) Vesta gravitational perturbations due to harmonics up to degree n = 3. This paper presents a pure vision based approach to solving for the gravitational field of extraterrestrial bodies with image data obtained by an orbiting spacecraft or satellite. Recovering a spacecraft's trajectory with modern day Structure from Motion approaches allows for further investigation for perturbations to accelerations due to variation in the strength of gravity. Understanding the variations of these forces, as well as developing a map, help to derive various models on the interior structure of the target planetary body or asteroid [1,4].Classical approaches for recovering the strength of a gravitational field study the motion of a satellite by tracking its position with Earth based telescopes. The basic principle behind this approach was developed in the field of satellite geodesy with the specific goal to define a highly accurate map of Earth's gravitational field. The same principle has not changed significantly, where the use of X-band Doppler and range measurements from a collection of Earth based radiometric tracking stations, known as the Deep Space Network, has been used to great effect.In this paper, we introduce method to recover an estimate of the gravitational field without any need of radiometric tracking. We formulate constraints on a set of spherical harmonic coefficients, which defines a map of gravitational variations on a sphere, as shown in Figure 1, that integrate with graphical models used in modern Structure from Motion techniques [2,3,6]. Our approach is a complete image-based pipeline based around a two-step optimization that recovers 3D structure, spacecraft kinematics, and a gravitational model.The basic process for gravity estimation is a two step iterative optimization. First, spacecraft pose and 3D landmark variables are estimated using batch bundle adjustment. The second step involves optimizing for the parameters of the gravitational field, in addition to camera pose velocities, using the local solutions found in step one. Here, tracking residuals are minimized with respect to global models.Development of two key error terms for recovering the gravitational field are presented. First, a dynamics based gravitational potential function is used to compare the error of a point mass' orbiting trajectory with the recovered camera positions given a set of spherical harmonic coefficients. The spherical harmonics, commonly referred to as Stokes coefficients, define a basis for the gravitational model, similar to a Fourier series but instead map to the surface of a unit sphere. This is the key error term behind recovering the gravitational perturbations. A second error term based upon the Kaula power law constrains the magnitude of the harmonic coefficients as a function of their degree.We evaluated our approach using camera data from the DAWN spacecraft's orbits around 4 Vesta, the second largest astero...

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A Global Solution for the Gravity Field, Rotation, Landmarks, and Ephemeris of Eros

Cited by 80 publications

References 15 publications

Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

Origin, Internal Structure and Evolution of 4 Vesta

An Image Based Approach to Recovering the Gravitational Field of Asteroids

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