LINK<\/strong><\/a><\/p>\n\n\n\n“Asteroid (2) Pallas is the largest main-belt object not yet visited by a spacecraft, making its surface geology largely unknown and limiting our understanding of its origin and collisional evolution. Previous ground-based observational campaigns returned different estimates of its bulk density that are inconsistent with one another, one measurement1 being compatible within error bars with the icy Ceres (2.16\u2009\u00b1\u20090.01\u2009g\u2009cm\u22123)2 and the other3 compatible within error bars with the rocky Vesta (3.46\u2009\u00b1\u20090.03\u2009g\u2009cm\u22123)4. Here we report high-angular-resolution observations of Pallas performed with the extreme adaptive optics-fed SPHERE imager5 on the Very Large Telescope. Pallas records a violent collisional history, with numerous craters larger than 30\u2009km in diameter populating its surface and two large impact basins that could be related to a family-forming impact. Monte Carlo simulations of the collisional evolution of the main belt correlate this cratering record to the high average impact velocity of ~11.5\u2009km\u2009s\u22121 on Pallas\u2014compared with an average of ~5.8\u2009km\u2009s\u22121 for the asteroid belt\u2014induced by Pallas\u2019s high orbital inclination (i\u2009=\u200934.8\u00b0) and orbital eccentricity (e\u2009=\u20090.23). Compositionally, Pallas\u2019s derived bulk density of 2.89\u2009\u00b1\u20090.08\u2009g\u2009cm\u22123 (1\u03c3 uncertainty) is fully compatible with a CM chondrite-like body, as suggested by its spectral reflectance in the 3\u2009\u03bcm wavelength region6. A bright spot observed on its surface may indicate an enrichment in salts during an early phase of aqueous alteration, compatible with Pallas\u2019s relatively high albedo of 12\u201317% (refs. 7,8), although alternative origins are conceivable.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Micha\u00ebl Marsset, Miroslav Bro\u017e, Pierre Vernazza, Alexis Drouard, Julie Castillo-Rogez, Josef Hanu\u0161, Matti Viikinkoski, Nicolas Rambaux, Beno\u00eet Carry, Laurent Jorda, Pavel \u0160eve\u010dek, Mirel Birlan, Franck Marchis, Edyta Podlewska-Gaca, Erik Asphaug, Przemyslaw Bartczak, J\u00e9r\u00f4me Berthier, Fabrice…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,5445,9,18],"tags":[1854,4438,3274,3273,105,1404,812],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21437"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=21437"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21437\/revisions"}],"predecessor-version":[{"id":21439,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/21437\/revisions\/21439"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21437"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21437"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21437"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}