A New Dawn Since 17 July 2011, NASA's spacecraft Dawn has been orbiting the asteroid Vesta—the second most massive and the third largest asteroid in the solar system (see the cover). Russell et al. (p. 684 ) use Dawn's observations to confirm that Vesta is a small differentiated planetary body with an inner core, and represents a surviving proto-planet from the earliest epoch of solar system formation; Vesta is also confirmed as the source of the howardite-eucrite-diogenite (HED) meteorites. Jaumann et al. (p. 687 ) report on the asteroid's overall geometry and topography, based on global surface mapping. Vesta's surface is dominated by numerous impact craters and large troughs around the equatorial region. Marchi et al. (p. 690 ) report on Vesta's complex cratering history and constrain the age of some of its major regions based on crater counts. Schenk et al. (p. 694 ) describe two giant impact basins located at the asteroid's south pole. Both basins are young and excavated enough amounts of material to form the Vestoids—a group of asteroids with a composition similar to that of Vesta—and HED meteorites. De Sanctis et al. (p. 697 ) present the mineralogical characterization of Vesta, based on data obtained by Dawn's visual and infrared spectrometer, revealing that this asteroid underwent a complex magmatic evolution that led to a differentiated crust and mantle. The global color variations detailed by Reddy et al. (p. 700 ) are unlike those of any other asteroid observed so far and are also indicative of a preserved, differentiated proto-planet.

Space weathering

Albedo (alchemy)

Regolith

10.1126/science.1219088

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Citations (173)

Asteroid Ryugu before the Hayabusa2 encounter

Progress in Earth and Planetary Science (2018)

Koji Wada M. Grott Patrick Michel K. J. Walsh A. M. Barucci

Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is very limited prior to Hayabusa2 observation. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on ground-based remote sensing and theoretical modeling before the Hayabusa2's arrival at the asteroid. This information is used to construct a design reference model of the asteroid that is used for the formulation of mission operation plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the solar system evolution that small bodies shed light on.

Near-Earth object

10.1186/s40645-018-0237-y

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Citations (53)

DAWN Framing Camera results from Ceres orbit

European Planetary Science Congress (2015)

A. Nathues M. Hoffmann M. Schäfer L. Le Corre V. Reddy

Framing (construction)

Source

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Citations (0)

Spectrophotometric Properties of 162173 Ryugu’s Surface from the NIRS3 Opposition Observations

The Planetary Science Journal (2021)

D. L. Domingue K. Kitazato M. Matsuoka Y. Yokota Eri Tatsumi

Abstract Examination of the opposition geometry properties show that Ryugu’s surface regolith is commensurate with laboratory studies of the photometric behavior of powdered carbonaceous chondrites. The regolith is consistent with a broad grain size distribution that contains a fine-grained component.

Regolith

Opposition (politics)

10.3847/psj/ac14bb

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Citations (4)

Processing of AMICA and NIRS Observations of Asteroid Itokawa from the Hayabusa Mission

L. Le Corre K. J. Becker V. Reddy J. Y. Li Roberto Furfaro

Source

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Citations (2)

Pre-Processing of Planetary Image Data for Photometric Model Creation by Spatial Context Functions

EPSC-DPS Joint Meeting 2011 (2011)

M. Hoffmann A. Nathues L. Le Corre V. Reddy

Spatial contextual awareness

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Asteroid Ryugu Before the Hayabusa2 Encounter

arXiv (Cornell University) (2018)

Koji Wada M. Grott Patrick Michel K. J. Walsh A. M. Barucci

Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is still very limited. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on remote sensing and theoretical modeling. This information is used to construct a design reference model of the asteroid that is used for formulation of mission operations plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the Solar System evolution that small bodies shed light on.

10.48550/arxiv.1804.03734

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Citations (1)