{"id":36265,"date":"2024-06-01T10:57:29","date_gmt":"2024-06-01T08:57:29","guid":{"rendered":"https:\/\/karmaka.de\/?p=36265"},"modified":"2024-06-01T11:03:15","modified_gmt":"2024-06-01T09:03:15","slug":"469219-kamo%ca%bboalewa-a-space-weathering-matured-small-nea-target-of-the-tianwen-2-sample-return-mission","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=36265","title":{"rendered":"(469219) Kamo\u02bboalewa, A Space Weathering Matured Small NEA: Target of the Tianwen-2 Sample-Return Mission<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Yang Li, Pengfei Zhang, Guozheng Zhang, Xiaoran Yan, Mikael Granvik, Yongxiong Zhang, Yunbo Niu, and 39 more authors<\/p>\n\n\n\n<p>Nature PREPRINT under review, Version 1, posted 29 May, 2024<\/p>\n\n\n\n<p><a href=\"https:\/\/www.researchsquare.com\/article\/rs-4281601\/v1?redirect=\/article\/rs-4281601\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/www.researchsquare.com\/article\/rs-4281601\/v1.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Understanding the nature and evolution of near-Earth asteroids (NEAs) are of paramount importance to planetary science1 and security2. So far, three asteroid sample-return missions, Hayabusa, Hayabusa2, and OSIRIS-REx to asteroids have greatly increased our knowledge of several-hundred-meter rubble-pile NEAs. However, limited by ground-based observation spatial resolution, little is known about smaller NEAs. Recently, the China National Space Administration has proposed a new asteroid mission, Tianwen-2, which plans to first return a sample from an Earth quasi-satellite (469219) 2016 HO3 Kamo\u02bboalewa, and then orbit and characterize an active main-belt asteroid: 311P\/PANSTARRS. Here we report that Kamo\u02bboalewa is an S-type, sub-hundred-meter-sized (69.45 m \u00d7 58.49 m \u00d7 51.78 m), rapid-rotating (period is 27.37 minutes) NEA developed with grain size &lt; 2 cm regolith. We analyzed telescopic observations of Kamo\u02bboalewa, whose visible to near-infrared (VIS-NIR) reflectance spectrum shows a 0.984 (+0.003,-0.004) \u03bcm absorption center, suggesting that it resembles LL ordinary chondrites in composition. Orbital dynamical calculations show that Kamo\u02bboalewa holds a 72 \u00b1 5% probability of originating from the inner main belt \u03bd6 secular resonance adjacent to the Flora family. Notably, Kamo\u02bboalewa exhibits an extremely red (positively steep) VIS-NIR spectral slope, making it a typical space weathering (SW)-matured object. Our spectral model calculations further suggest that the sub-microphase iron content in Kamo\u02bboalewa\u2019s regolith is 0.29 \u00b1 0.05 wt.% and the SW timescale is ~0.5\u20131 \u00d7 10^8 years. This means that Kamo\u02bboalewa is indeed a SW-matured object and the separation from its parent body likely took place in the inner main belt long before it evolved into an NEA. We ascribe Kamo\u02bboalewa\u2019s extremely red spectral slope to the combined effects of SW, YORP spin-up, thermal degradation, low-frequency impacts, and non-rubble pile structure. We further predict that sub-hundred-meter, rapidly spinning silicate-rich NEAs with small perihelion may generally exhibit extremely red spectral slopes and SW-matured surfaces.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yang Li, Pengfei Zhang, Guozheng Zhang, Xiaoran Yan, Mikael Granvik, Yongxiong Zhang, Yunbo Niu, and 39 more authors Nature PREPRINT under review, Version 1, posted 29 May, 2024 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;Understanding the&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,3035,181,3504],"tags":[6168,6678,1760,4827,4899,673,6677],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36265"}],"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=36265"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36265\/revisions"}],"predecessor-version":[{"id":36267,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36265\/revisions\/36267"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36265"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36265"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36265"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}