{"id":41085,"date":"2026-03-31T11:55:53","date_gmt":"2026-03-31T09:55:53","guid":{"rendered":"https:\/\/karmaka.de\/?p=41085"},"modified":"2026-03-31T11:58:08","modified_gmt":"2026-03-31T09:58:08","slug":"shape-regolith-size-and-thickness-smfe0-content-and-spectral-type-of-tianwen-2-target-asteroid-469219-kamooalewa","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=41085","title":{"rendered":"Shape, regolith size and thickness, SMFe^0 content, and spectral type of Tianwen-2 target asteroid (469219) Kamo&#8217;oalewa<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Pengfei Zhang, Guozheng Zhang, Yongxiong Zhang, Marco Fenucci, Pierre Vernazza, Jin Zhao, Yunbo Niu, Xuejin Lu, Xing Wu, Honglei Lin, Edward Cloutis, Xiaoran Yan, Xiaoping Lu, Xiaobin Wang, Xiaoping Zhang, Yang Li<\/p>\n\n\n\n<p>under revision in Astronomy &amp; Astrophysics, March 31, 2026<\/p>\n\n\n\n<p><a href=\"https:\/\/arxiv.org\/pdf\/2603.28107\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Context. China\u2019s Tianwen-2 spacecraft will return samples from the near-Earth asteroid (469219) Kamo\u2018oalewa. We previously reported that Kamo\u2018oalewa develops an LL-chondrite-compositional, highly space-weathered surface.<br>Aims. This study aims to estimate Kamo\u2018oalewa\u2019s shape, regolith grain size and thickness, sub-micrometer iron (SMFe0) content, and spectral type.<br>Methods. Using the lightcurve data and the Cellinoid model, we modeled Kamo\u2018oalewa\u2019s shape, rotation period, and pole orientation. We then estimated its global distribution of regolith critical size using the balance method of gravity, cohesive force, and centrifugal force. Furthermore, in the temperature range of 253.15 to 473.15 K, we measured the thermal parameters of laser-irradiated LL chondrite powder that best matches Kamo\u2018oalewa\u2019s spectrum, estimating Kamo\u2018oalewa\u2019s thermal inertia and skin depth (lower limit of regolith thickness). Using the radiative transfer mixing model, we also estimated the content of SMFe0 in Kamo\u2018oalewa\u2019s regolith. Finally, using the MIT online spectral classification tool for the laser-irradiated LL chondrite powder, we obtained a virtual spectral type of Kamo\u2018oalewa.<br>Results. Our model gives a size of 68 m \u00d7 46 m \u00d7 39 m, a rotation period of 27.66 minutes, and a pole orientation of 134.7\u25e6 longitude and \u221211.4\u25e6 latitude for kamo\u2018oalewa. Regolith grains with a size &lt;2 cm can remain stable over 93.8% of the global surface area of Kamo\u2018oalewa. Laser-irradiated LL chondrite powder shows a low thermal inertia (95.5 to 135.1 J m\u22122 K\u22121 s\u22121\/2), corresponding to a thermal skin depth of 3 to 3.5 mm on Kamo\u2018oalewa. An SMFe0 content of 0.29 \u00b1 0.05 wt.% is required to match Kamo\u2018oalewa\u2019s spectrum. The virtual spectral type of Kamo\u2018oalewa is given as \u201cSqw\u201d.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Pengfei Zhang, Guozheng Zhang, Yongxiong Zhang, Marco Fenucci, Pierre Vernazza, Jin Zhao, Yunbo Niu, Xuejin Lu, Xing Wu, Honglei Lin, Edward Cloutis, Xiaoran Yan, Xiaoping Lu, Xiaobin Wang, Xiaoping Zhang, Yang Li under revision in&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77,130,181,3504,1184],"tags":[6168,1854,263,6197,1479,4899,270,6242,6677],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41085"}],"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=41085"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41085\/revisions"}],"predecessor-version":[{"id":41087,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/41085\/revisions\/41087"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41085"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41085"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41085"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}