Motopi Pan        21.24848°S, 23.23866°E

Central Kalahari Game Reserve, Botswana

Confirmed fall: 2018 June 2

Classification: HED achondrite (Howardite)

History (M. Gabadirwe, A. Proyer, O. Moses, P. Jenniskens, T. Kohout): A fresh meteorite (specimen MP-01) was found in the Central Kalahari Game Reserve of Botswana on 23 June 2018 during a dedicated search by a team of geoscientists from BIUST, BGI, ORI, and SETI. The fall area was determined by SETI and UHelsinki. Asteroid 2018 LA was detected in space by the Catalina Sky Survey, operated by UAz, eight hours before hitting Earth on 2 June 2018 at 16:44 hrs UTC. Subsequent searches were conducted between 2018 June and September, and in 2018 October a team representing BGI, ORI, SETI, Department of National Museum and Monuments (DNMM), Department of Wildlife & National Parks (DWNP), and the Astronomical Society of South Africa (ASSA) recovered an additional 23 meteorites. The meteorites were sent to BGI for curation, bringing the total to date to 23 specimens. This is the third time in history that an asteroid inbound to hit Earth was detected early and only the second time that fragments were recovered (see Almahata Sitta).

Physical characteristics: (M. Gabadirwe, BGI, P. Jenniskens, SETI, and T. Kohout, UHelsinki) The total mass of the 24 recovered specimens is 214.5 g. MP-01 bulk density 2.85 g/cm³, grain density 3.26 g/cm³, porosity 13%

Petrography: (R.L. Gibson and L.D. Ashwal, Wits): Five fragments classified. Polymict eucrite breccia derived primarily from cumulate and basaltic eucrite lithologies, but with >10% diogenite component, indicating a howardite. Two fragments comprise roughly equal proportions of texturally well-equilibrated, phaneritic, low-Ca pyroxene (orthopyroxene?) and plagioclase with 1 mm grain size, and minor to trace chromite and troilite (cumulate eucrite). The third fragment is dominated by texturally well-equilibrated, phaneritic, low-Ca pyroxene (>90%) with minor interstitial plagioclase and olivine and subsidiary troilite and chromite (diogenite). The remaining two fragments are breccias comprising a fragmental to fused plagioclase + low-Ca pyroxene matrix. Angular to subrounded mineral clasts in these breccias are predominantly low-Ca pyroxene and plagioclase (commonly >0.2 mm size); lithic clasts are angular and comprise phaneritic cumulate eucrite/diogenite and subophitic-textured basalt up to 3 mm in size; a 4 × 3 mm wide clast of an older breccia is enclosed within younger breccia. Ilmenite and troilite occur as fine inclusions and blebs in clasts and more rarely as discrete mineral clasts. Parallel exsolution lamellae of high-Ca pyroxene up to tens of microns wide are common in low-Ca pyroxene mineral clasts in the breccias, but are not ubiquitous. Exsolution-free low-Ca pyroxene clasts may be zoned, with Mg-depletion at their margins and adjacent to internal fractures. Also present are clasts with intergrown plagioclase, silica and high-Ca pyroxene with troilite, ilmenite and chromite inclusions. Pyroxene and plagioclase compositions are highly variable in the breccias. Pyroxene exsolution lamellae are displaced along fractures and two fragments contain mm-wide fracture-hosted melt breccia veins.

Geochemistry: Mineral compositions and geochemistry: (L.D. Ashwal and A. Ziegler, Wits) Polymict eucrite breccia (howardite): lithic and mineral clasts: low-Ca pyroxene (Fs_41.6±8.9Wo_4.6±2.4; n=57), plagioclase (Ab_13.7±4.9An_85.4±5.3Or_0.90±0.79; n=24), chromite (Mg/(Mg+Fe) = 4.3±0.4; Cr/(Cr+Al) = 66.1±0.2; n=4), ilmenite (MgO = 0.53±0.13; MnO = 1.10±0.17; n=16). Coarsely exsolved pyroxenes: low-Ca pyroxene host (Fs_48.9±1.4Wo_10.0±1.9; n=9), high-Ca pyroxene lamellae (Fs_27.0±0.9Wo_{36.4± 0.9}; n=10). Cumulate eucrite: low-Ca pyroxene (Fs_33.9±2.0Wo _4.5±1.5; n=69), plagioclase (Ab_4.4.±0.6An _95.5±0.6Or_0.18±0.10; n=57), chromite (Mg/(Mg+Fe) = 10.8±1.7; Cr/(Cr+Al) = 66.2±2.8; n=16). Diogenite: low-Ca pyroxene (Fs_26.8±0.8Wo_3.4±0.4; n=7), plagioclase (Ab_5.2±0.7An_94.7±0.7Or_0.15±0.04; n=15), olivine (Fa_39.5±3.5; n=12), chromite (Mg/(Mg+Fe) = 18.7±0.1; Cr/(Cr+Al) = 64.7±0.4; n=3).

Classification: Basaltic achondrite group / HED clan / Howardite

Specimens: A table of finds appears below in the Geography section. A consortium report on the impact and recovery of asteroid 2018 LA is published in Jenniskens et al. (2021).