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An asteroid is a minor planet—an object that is neither a true planet nor a comet—that orbits within the inner Solar System. They are rocky, metallic or icy bodies with no atmosphere. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter.
Vesta is one of the largest objects in the asteroid belt, with a mean diameter of 525 kilometres (326 mi). It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, the virgin goddess of home and hearth from Roman mythology.
Pallas is the second asteroid to have been discovered, after Ceres. It is believed to have a mineral composition similar to carbonaceous chondrite meteorites, like Ceres, though significantly less hydrated than Ceres. It is the third-largest asteroid in the Solar System by both volume and mass, and is a likely remnant protoplanet. It is 79% the mass of Vesta and 22% the mass of Ceres, constituting an estimated 7% of the mass of the asteroid belt. Its estimated volume is equivalent to a sphere 507 to 515 kilometers in diameter, 90–95% the volume of Vesta.
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System.
Dawn is a retired space probe that was launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt: Vesta and Ceres. In the fulfillment of that mission—the ninth in NASA's Discovery Program—Dawn entered orbit around Vesta on July 16, 2011, and completed a 14-month survey mission before leaving for Ceres in late 2012. It entered orbit around Ceres on March 6, 2015. In 2017, NASA announced that the planned nine-year mission would be extended until the probe's hydrazine fuel supply was depleted. On November 1, 2018, NASA announced that Dawn had depleted its hydrazine, and the mission was ended. The derelict probe remains in a stable orbit around Ceres.
Adeona is a large asteroid from the intermediate asteroid belt, approximately 150 kilometers in diameter. Its surface is very dark, and, based upon its classification as a C-type asteroid, is probably composed of primitive carbonaceous material. The spectra of the asteroid displays evidence of aqueous alteration. The Adeona family of asteroids is named after it.
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. All terrestrial planets, a number of asteroids, and some planetary moons have mantles.
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of celestial bodies such as planets and their moons, asteroids, comets, and meteorites. Although the geo- prefix typically indicates topics of or relating to Earth, planetary geology is named as such for historical and convenience reasons; due to the types of investigations involved, it is closely linked with Earth-based geology. These investigations are centered around the composition, structure, processes, and history of a celestial body.
Christopher Thomas Russell is head of the Space Physics Center at the Institute of Geophysics and Planetary Physics (IGPP) at UCLA, professor in UCLA's Department of Earth, Planetary, and Space Sciences, and Director of the UCLA Branch of the California Space Grant Consortium. He received a B.Sc. from the University of Toronto in 1964 and a Ph.D. from UCLA in 1968. In 1977 he was awarded the James B. Macelwane Medal and in 2003 the John Adam Fleming Medal by the American Geophysical Union (AGU). He is also a Fellow of the AGU. Asteroid 21459 Chrisrussell was named after him in 2008. In 2017, he was awarded the NASA Distinguished Public Service Medal. He has three grandchildren.
A sample-return mission is a spacecraft mission to collect and return samples from an extraterrestrial location to Earth for analysis. Sample-return missions may bring back merely atoms and molecules or a deposit of complex compounds such as loose material and rocks. These samples may be obtained in a number of ways, such as soil and rock excavation or a collector array used for capturing particles of solar wind or cometary debris. Nonetheless, concerns have been raised that the return of such samples to planet Earth may endanger Earth itself.
HED meteorites are a clan (subgroup) of achondrite meteorites. HED stands for "howardite–eucrite–diogenite". These achondrites came from a differentiated parent body and experienced extensive igneous processing not much different from the magmatic rocks found on Earth and for this reason they closely resemble terrestrial igneous rocks.
Ceres, minor-planet designation 1 Ceres, is a dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. It was the first asteroid discovered, on 1 January 1801, by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily and announced as a new planet. Ceres was later classified as an asteroid and then a dwarf planet, the only one always inside Neptune's orbit.
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets. The prototypical dwarf planet is Pluto. The interest of dwarf planets to planetary geologists is that they may be geologically active bodies, an expectation that was borne out in 2015 by the Dawn mission to Ceres and the New Horizons mission to Pluto.
The Planetary Science Institute (PSI) is a 501(c)(3) non-profit research institute based in Tucson, Arizona, focusing on planetary science. As of 2018, its director is Dr. Mark V. Sykes. PSI, along with Space Science Institute (SSI) Southwest Research Institute (SwRI), and Eureka Scientific, were listed as 501(c)(3) organizations in the US in a special report by Nature in 2007, which facilitate federal grant applications of non-tenure-track astronomers.
Carle McGetchin Pieters is an American planetary scientist. Pieters has published more than 150 research articles in peer-reviewed journals and was co-author of the book Remote Geochemical Analyses: Elemental and Mineralogical Composition along with Peter Englert. Her general research efforts include planetary exploration and evolution of planetary surfaces with an emphasis on remote compositional analyses.
Rheasilvia is the most prominent surface feature on the asteroid Vesta and is thought to be an impact crater. It is 505 km (314 mi) in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta, 529 km (329 mi). However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of 569 km (354 mi), making it one of the largest craters in the Solar System, and at 75°S latitude, covers most of the southern hemisphere. The peak in the center of the crater is 200 km (120 mi) in diameter, and rises 22.5 km from its base, making it one of the tallest mountains known in the Solar System.
Veneneia is the second-largest crater on asteroid 4 Vesta, at 52°S latitude. 395 kilometres (245 mi) in diameter, it is 70% of the equatorial diameter of the asteroid, and one of the largest craters in the Solar System. It is at least 2 billion years old, and possibly as old as 4.2 billion years. However, it is overlain and partially obliterated by the even larger Rheasilvia. It was discovered by the Dawn spacecraft in 2011. It is named after Venēneia, one of the founding vestal virgins.
Renoir is a crater on the planet Mercury. Its name, after the French painter Pierre-Auguste Renoir (1841–1919), was adopted by the International Astronomical Union in 1976.
Lucy-Ann Adams McFadden is an American astronomer and planetary scientist. An employee of the National Aeronautics and Space Administration, she also founded the Science, Discovery & the Universe Program within the University of Maryland, and the Explore-It-All Science Center, a children's science program.
References
- ↑ Target: Vesta, Gazetteer of Planetary Nomenclature
- ↑ Schenk, Paul (2012). "The Geologically Recent Giant Impact Basins at Vesta's South Pole". Science. 336 (6082): 694–697. Bibcode:2012Sci...336..694S. doi:10.1126/science.1223272. PMID 22582256.
- ↑ Vega, P. (11 October 2011). "New View of Vesta Mountain From NASA's Dawn Mission". dawn.jpl.nasa.gov. NASA. Archived from the original on 2013-10-17. Retrieved 2018-02-17.