Gamma-ray and neutron spectrometer for the Dawn mission to 1 Ceres and 4 Vesta

Prettyman, T. H.; Feldman, W. C.; Ameduri, F. P.; Barraclough, B. L.; Cascio, E; Fuller, K. R.; Funsten, H. O.; Lawrence, D. J.; McKinney, G.W.; Russell, C. T.; Soldner, S.A.; Storms, S. A.; Szeles, Csaba; Tokar, R. L.

doi:10.1109/tns.2003.815156

Cited by 36 publications

(22 citation statements)

References 23 publications

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“…The elements that can be analyzed by GRaND are limited (Prettyman et al 2003). The mixing model can theoretically estimate not only major elements but also minor and trace elements such as Ni, Cr, Mn, P, rare earth elements, and others, if they are given by the three endmember components and a sufficient HED database exists.…”

Section: Estimation Of Elements Not Analyzed By Grandmentioning

confidence: 99%

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Geochemistry of 4 Vesta based on HED meteorites: Prospective study for interpretation of gamma ray and neutron spectra for the Dawn mission

Usui

McSween

2007

Meteorit & Planetary Scien

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Abstract-Asteroid 4 Vesta, believed to be the parent body of the howardite, eucrite, and diogenite (HED) meteorites, will be investigated by the Dawn orbiting spacecraft. Dawn carries a gamma ray and neutron detector (GRaND) that will measure and map some major-and trace-element abundances. Drawing on HED geochemistry, we propose a mixing model that uses element ratios appropriate for the interpretation of GRaND data.Because the spatial resolution of GRaND is relatively coarse, the analyzed chemical compositions on the surface of Vesta will likely reflect mixing of three endmember components: diogenite, cumulate eucrite, and basaltic eucrite. Reliability of the mixing model is statistically investigated based on published whole-rock data for HED meteorites. We demonstrate that the mixing model can accurately estimate the abundances of all the GRaND-analyzed major elements, as well as of minor elements (Na, Cr, and Mn) not analyzed by this instrument. We also show how a similar mixing model can determine the modal abundance of olivine, and we compare estimated and normative olivine data for olivine-bearing diogenites. By linking the compositions of well-analyzed HED meteorites with elemental mapping data from GRaND, this study may help constrain the geological context for HED meteorites and provide new insight into the magmatic evolution of Vesta.

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Section: Estimation Of Elements Not Analyzed By Grandmentioning

confidence: 99%

“…The Dawn spacecraft is equipped with a gamma ray and neutron detector (GRaND) (Prettyman et al 2003). GRaND can directly measure the abundances and map the surface distributions of some major (O, Si, Fe, Ti, Mg, Al, and Ca) and trace (U, Th, H, and K) elements (Prettyman et al 2006.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of 4 Vesta based on HED meteorites: Prospective study for interpretation of gamma ray and neutron spectra for the Dawn mission

Usui

McSween

2007

Meteorit & Planetary Scien

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“…We will also provide an update on the GRaND instrument and its expected performance at Vesta and Ceres. This paper supplements a more detailed description of the instrument by Prettyman et al [2003].…”

Section: Introductionmentioning

confidence: 90%

Mapping the elemental composition of Ceres and Vesta: Dawn"s gamma ray and neutron detector

Prettyman

Feldman²,

Barraclough³

et al. 2004

SPIE Proceedings

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Dawn is a NASA discovery mission that will explore the main belt asteroids (1) Ceres and (4) Vesta. Ceres and Vesta are among the oldest bodies in the solar system and represent very different evolutionary paths. By studying these ancient, complementary asteroids, we will answer fundamental questions about the early solar system and planetary formation processes.The Dawn payload consists of a Framing Camera (FC), a visual and infrared mapping spectrometer (VIR), and a Gamma Ray and Neutron Detector (GRaND). The instruments provide data needed to investigate the structure, geology, mineralogy, and geochemistry of the asteroids. GRaND provides the data for the geochemistry investigation, including maps of most major elements and selected radioactive and trace elements. An updated description of the GRaND instrument is given along with the expected performance of GRaND at Vesta and Ceres. Approaches to combine data from FC, VIR and GRaND are discussed.

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“…It draws on decades of experience at LANL in measuring neutrons and energetic photons and is an improved version of the highly successful GR/NS on Lunar Prospector (LP), and the presently operating Neutron Spectrometer aboard Mars Odyssey (MO). The design of the spectrometer and its expected performance is described in detail by Prettyman, et al, 2003. The gamma-ray sensor is segmented into two parts and the neutron sensor into four parts.…”

Section: Gamma Ray/neutron Spectrometermentioning

confidence: 99%

“…The exposure predicted for the CZT behind the ACS is low enough that we do not anticipate significant degradation in performance due to radiation damage. However, to ensure performance, our design includes the capability to anneal the CZT array if damage is observed [Prettyman, et al, 2003]. …”

Section: Gamma Ray/neutron Spectrometermentioning

confidence: 99%

Dawn: A journey in space and time

Russell¹,

Coradini²,

Christensen³

et al. 2004

Planetary and Space Science

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By successively orbiting both 4 Vesta and 1 Ceres the Dawn mission directly addresses the long-standing goals of understanding the origin and evolution of the solar system. Ceres and Vesta are two complementary terrestrial protoplanets (one apparently "wet" and the other "dry"), whose accretion was probably terminated by the formation of Jupiter. They provide a bridge in our understanding between the rocky bodies of the inner solar system and the icy bodies of the outer solar system. Ceres appears to be undifferentiated while Vesta has experienced significant heating and likely differentiation. Both formed very early in the history of the solar system and while suffering many impacts have remained intact, thereby retaining a record of events and processes from the time of planet formation. Detailed study of the geophysics and geochemistry of these two bodies provides critical benchmarks for early solar system conditions and processes that shaped its subsequent evolution. Dawn provides the missing context for both primitive and evolved meteoritic data, thus playing a central role in understanding terrestrial planet formation and the evolution of the asteroid belt. Dawn is to be launched in May 2006 arriving at Vesta in 2010 and Ceres in 2014, stopping at each to make 11 months of orbital measurements. The spacecraft uses solar electric propulsion, both in cruise and in orbit, to make most efficient use of its xenon propellant. The spacecraft carries a framing camera, visible and infrared mapping spectrometer, gamma ray/neutron spectrometer, magnetometer, and radio science.3

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Gamma-ray and neutron spectrometer for the Dawn mission to 1 Ceres and 4 Vesta

Cited by 36 publications

References 23 publications

Geochemistry of 4 Vesta based on HED meteorites: Prospective study for interpretation of gamma ray and neutron spectra for the Dawn mission

Geochemistry of 4 Vesta based on HED meteorites: Prospective study for interpretation of gamma ray and neutron spectra for the Dawn mission

Mapping the elemental composition of Ceres and Vesta: Dawn"s gamma ray and neutron detector

Dawn: A journey in space and time

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