{"id":41814,"date":"2026-06-13T10:22:35","date_gmt":"2026-06-13T08:22:35","guid":{"rendered":"https:\/\/karmaka.de\/?p=41814"},"modified":"2026-06-13T10:22:36","modified_gmt":"2026-06-13T08:22:36","slug":"the-role-of-composition-in-the-spectral-evolution-of-carbonaceous-asteroids-as-informed-by-bennu-sample-return","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=41814","title":{"rendered":"The role of composition in the spectral evolution of carbonaceous asteroids as informed by Bennu sample return<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Ralph E. Milliken, Takahiro Hiroi, Victoria E. Hamilton, Cody D. Schultz, Ed A. Cloutis, Hannah H. Kaplan, Melissa K. Kontogiannis, Nathalia Vega-Santiago, Dani N. DellaGiustina, Harold C. Connolly Jr., Dante S. Lauretta<\/p>\n\n\n\n<p>MAPS, Version of Record online: 12 June 2026<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.70179\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.70179\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Near-Earth rubble-pile asteroids Bennu and Ryugu are part of the carbonaceous taxonomic complex (C-complex), and samples returned from both bodies resemble the most aqueously altered carbonaceous chondrites. However, telescopic and spacecraft visible\u2013near infrared (VIS\u2013NIR) reflectance spectra of Ryugu exhibit a red (positive) spectral slope, whereas Bennu has a blue (negative) spectral slope characteristic of the rare B-type subclass of asteroids. The asteroid spectra also suggest different levels of hydration, with Ryugu dominated by OH and Bennu containing spectral evidence of more H2O. To understand what causes these differences, we acquired VIS\u2013NIR reflectance data (~0.3\u20135\u2009\u03bcm) from a variety of Bennu samples over spatial scales of 100 \u03bcm to several millimeters. No single sample reproduces the average spectral properties of Bennu, but by evaluating samples of different petrology and physical states\u2014groups of particles, isolated particles, and larger stones\u2014we demonstrate that primary composition, and highly hydrated Mg-rich phosphate in particular, plays a strong role in controlling the spectral slope and average hydration absorption strength of Bennu materials. Bennu and Ryugu may be dominated by different lithologies originating from different regions of a common planetesimal, thus explaining their different spectral evolution. The spectral characteristics of B-type asteroids, particularly those with blue slopes at near-infrared wavelengths and broad hydration features at ~3\u2009\u03bcm, may indicate the presence of Mg phosphate and thus a history of complex fluid\u2013rock interactions relevant to prebiotic chemistry.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ralph E. Milliken, Takahiro Hiroi, Victoria E. Hamilton, Cody D. Schultz, Ed A. Cloutis, Hannah H. Kaplan, Melissa K. Kontogiannis, Nathalia Vega-Santiago, Dani N. DellaGiustina, Harold C. Connolly Jr., Dante S. Lauretta MAPS, Version of&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,2350,2243,552,130],"tags":[5719,3872,1854,5789,1974,3274,4851,7208,2867,4899,6259],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41814"}],"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=41814"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41814\/revisions"}],"predecessor-version":[{"id":41815,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41814\/revisions\/41815"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41814"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41814"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41814"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}