The Golden meteorite fall: Fireball trajectory, orbit, and meteorite characterization

The Golden (British Columbia, Canada) meteorite fall occurred on October 4, 2021 at 0534 UT with the first recovered fragment (1.3 kg) landing on an occupied bed. The associated fireball was recorded by numerous cameras permitting reconstruction of its trajectory and orbit. The fireball entered the atmosphere at a 54° angle from the horizontal at a speed of 18 km s−1. The fireball reached a peak brightness of −14, having first become luminous at a height of >84 km and ending at 18 km altitude. Analysis of the infrasonic record of the bolide produced an estimated mass of (Formula presented.) kg while modeling of the fireball light curve suggests an initial mass near 70 kg. The fireball experienced a major flare near 31 km altitude where more than half its mass was lost in the form of dust and gram-sized fragments under a dynamic pressure of 3.3 MPa. The strength and fragmentation behavior of the fireball were similar to those reported for other meteorite-producing fireballs (Borovička et al., 2020). Seven days after the fireball occurred, an additional 0.9 kg fragment was recovered during the second day of dedicated searching guided by initial trajectory and dark flight calculations. Additional searching in the fall and spring of 2021–2022 located no additional fragments. The meteorite is an unbrecciated, low-shock (S2) ordinary chondrite of intermediate composition, typed as an L/LL5 with a grain density of ~3530 k gm−3, an average bulk density of 3150 kg m−3 and calculated porosity of ~10%. From noble gas measurements, the cosmic ray exposure age is 25 ± 4 Ma while gas retention ages are all >2 Ga. Short-lived radionuclides and noble gas measurements of the pre-atmospheric size overlap with estimates from infrasound and light curve modeling producing a preferred pre-atmospheric mass of 70–200 kg. The orbit of Golden has a high inclination (23.5°) and is consistent with delivery from the inner main belt. The highest probability (60%) of an origin is from the Hungaria group. We propose that Golden may originate among the background S-type asteroids found interspersed in the Hungaria region. The current collection of 18 L/LL—chondrite orbits shows a strong preference for origins in the inner main belt, suggesting multiple parent bodies may be required to explain the diversity in CRE ages and shock states

The Importance of Mars Samples in Constraining the Geological and Geophysical Processes on Mars and the Nature of its Crust, Mantle, and Core.

In situ compositional and mineralogical measurements on the Martian surface, combined with analyses of Martian meteorites, indicate that most igneous rocks are lavas and volcaniclastic rocks of basaltic composition and cumulates of ultramafic composition [1]. Alkaline rocks are common in Early Hesperian terranes and tholeiitic rocks dominate younger Amazonian martian meteorites [1]. Very uncommon feldspathic rocks represent the ultimate fractionation products, while granitoid rocks have not been identified [1]. The impact-driven delivery mechanism for the Martian meteorites [2] biases in favor of more competent samples – young, igneous rocks [e.g., 3] – and against rocks that are more representative of the Martian crust [e.g., 4]. Comparisons of rock types found among the meteorites to those documented by landed missions demonstrates this bias unequivocally [1]; furthermore, of the over 100 martian lithologies represented by the martian meteorites, only one (NWA 7034 and pairs) is a regolith breccia [e.g., 1, 5]. While the meteorites provide important insights into the nature of the silicate portion of Mars, including the origin of mantle components with differing geochemical characteristics [e.g., 6], they do not provide information on the composition of the original crust Mars, nor the nature of the mantle sources from which rocks at the Martian surface have been derived (e.g., igneous rocks at Gusev and Gale craters). Thus, there is much to be learned from the study of carefully selected samples from the martian surface

Evidence of impact melting and post-impact decomposition of sedimentary target rocks from the Steen River impact structure, Alberta, Canada

Hypervelocity bolide impacts deliver vast amounts of energy to the Earth's near surface. This crustal process almost universally includes sedimentary target rocks; however, their response to impact is poorly understood, in part because of complexities due to layering, pore space and the presence of volatiles that are difficult to model. The response of carbonates to bolide impact remains contentious, yet whether they melt or decompose and liberate gases by the reaction CaCO 3(s) → CaO (s) + CO 2(g) ↑, has significant implications for post-impact climatic effects. We report on previously unknown carbonate impact melts at the Steen River impact structure, Canada, and the first description of naturally shocked barite, BaSO 4 . Carbonate melts are preserved as groundmass-supported calcite-rich clasts, sampled from an up to 164 m thick, continuous sequence of crater-fill polymict breccias. Electron microscopy reveals fluidal- and ocellar-textured calcite and barite, intimately associated with silicate melt, consistent with these phases being in the liquid state at the same time. Raman spectroscopy and electron backscatter diffraction (EBSD) mapping confirm the presence of high-pressure phases – reidite and coesite – within some Steen River carbonate melt-bearing breccias. These minerals attest to the strong shock provenance of the breccia and provide constraints on their shock history. Preservation of reidite lamellae in zircon indicates a shock pressure >30 GPa <60 GPa and temperatures <1473 K. In addition to melting, we present compelling evidence for widespread (70–100%) decomposition of carbonate target rocks, mixed as lithic clasts into hot impact breccias. In this context, decomposition occurs strictly post-impact due to thermal equilibration-related heating. We demonstrate that this mechanism for CO 2 outgassing is likely more widespread than previously recognized. The presence of andradite-grossular garnet serve as mineralogical markers of decomposition, analogous to limestone-replacing skarn deposits. Ca-rich garnet may therefore prove an important indicator mineral for post-shock decomposition of carbonate-bearing target rocks at other craters. These findings significantly advance our understanding of how sedimentary rocks respond to hypervelocity impact, and have wide-reaching implications for estimating the amount and timing of climatically-active volatile release due to impact events

The source craters of the martian meteorites: Implications for the igneous evolution of Mars

Approximately 200 meteorites come from ∼10 impact events on the surface of Mars, yet their pre-ejection locations are largely unknown. Here, we combine the results of diverse sets of observations and modeling to constrain the source craters for several groups of martian meteorites. We compute that ejection-paired groups of meteorites are derived from lava flows within the top 26 m of the surface. We link ejection-paired groups to specific source craters and geologic units, providing context for these important samples, reconciling microscopic observations with remote sensing records, and demonstrating the potential to constrain the ages of their source geologic units. Furthermore, we show that there are craters that may have produced martian meteorites not represented in the world's meteorite collections that have yet to be discovered

Planning for Mars Returned Sample Science: Final Report of the MSR End-to-End International Science Analysis Group (E2E-iSAG)

Returning samples from Mars to Earth for scientific analysis has been, and continues to be, among the highest-priority objectives of planetary science. Partly for this reason, the 2011 Planetary Science Decadal Survey placed high priority on a proposed 2018 rover mission that would conduct careful in situ science and use that scientific information to select and cache samples that could be returned to Earth by a potential future mission. To ensure that the potential contributions of the 2018 rover to the proposed Mars Sample Return (MSR) Campaign are properly planned, this study was undertaken to consider the science of the MSR Campaign concept from end to end. This white paper is the principal output of the MSR End-to-End International Science Analysis Group (E2E-iSAG): a group chartered by the Mars Exploration Program Analysis Group (MEPAG)

A Global Fireball Observatory

The world’s meteorite collections contain a very rich picture of what the early Solar System would have been made of, however the lack of spatial context with respect to their parent population for these samples is an issue. The asteroid population is equally as rich in surface mineralogies, and mapping these two populations (meteorites and asteroids) together is a major challenge for planetary science. Directly probing asteroids achieves this at a high cost. Observing meteorite falls and calculating their pre-atmospheric orbit on the other hand, is a cheaperway to approach the problem. The Global Fireball Observatory (GFO) collaboration was established in 2017 and brings together multiple institutions (from Australia, USA, Canada, Morocco, Saudi Arabia, the UK, andArgentina) to maximise the area for fireball observation time and therefore meteorite recoveries. The membershave a choice to operate independently, but they can also choose to work in a fully collaborative manner withother GFO partners. This efficient approach leverages the experience gained from the Desert Fireball Network (DFN) pathfinder project in Australia. The state-of-the art technology (DFN camera systems and data reduction) and experience of the support teams is shared between all partners, freeing up time for science investigations and meteorite searching. With all networks combined together, the GFO collaboration already covers 0.6% of the Earth’s surface for meteorite recovery as of mid-2019, and aims to reach 2% in the early 2020s. We estimate that after 5 years of operation, the GFO will have observed a fireball from virtually every meteorite type. This combined effort will bring new, fresh, extra-terrestrial material to the labs, yielding new insights about the formation of the Solar System.Fil: Devillepoix, Adrien. Curtin University; AustraliaFil: Cupak, Martin. Curtin University; AustraliaFil: Hormaechea, José Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bland, P.A. Curtin University; AustraliaFil: Sansom, E.K. Curtin University; AustraliaFil: Towner, M.C. Curtin University; AustraliaFil: Howie, R.M. Curtin University; AustraliaFil: Hartig,B.A.D.. Curtin University; AustraliaFil: Jansen-Sturgeon,T.. Curtin University; AustraliaFil: Shober,P.M.. Curtin University; AustraliaFil: Anderson,S.L.. Curtin University; AustraliaFil: Benedix,G.K.. Curtin University; AustraliaFil: Busan, D.. Curtin University; AustraliaFil: Sayers, R.. Curtin University; AustraliaFil: Jenniskens,P.. Carl Sagan Center; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Albers,J.. Carl Sagan Center; Estados UnidosFil: Herd,C.D.K. University of Alberta; CanadáFil: Hill, P.J.A.. University of Alberta; CanadáFil: Brown,P.G.. University of Western Ontario; CanadáFil: Krzeminski, Z.. University of Western Ontario; CanadáFil: Osinski, G.R.. University of Western Ontario; CanadáFil: Chennaoui Aoudjehane, H.. University of Casablanca; MarruecosFil: Benkhaldoun, Z.. Cadi Ayyad University; MarruecosFil: Jabir, A.. Cadi Ayyad University; MarruecosFil: Guennoun,M.. Cadi Ayyad University; MarruecosFil: Barka, A.. Cadi Ayyad University; MarruecosFil: Darhmaoui,H.. Cadi Ayyad University; MarruecosFil: Collins,G.S.. Imperial College London; Reino UnidoFil: McMullan,S.. Imperial College London; Reino UnidoFil: Suttle,M.D.. Universita di Pisa ; Itali

A Global Fireball Observatory

The world's meteorite collections contain a very rich picture of what the early Solar System would have been made of, however the lack of spatial context with respect to their parent population for these samples is an issue. The asteroid population is equally as rich in surface mineralogies, and mapping these two populations (meteorites and asteroids) together is a major challenge for planetary science. Directly probing asteroids achieves this at a high cost. Observing meteorite falls and calculating their pre-atmospheric orbit on the other hand, is a cheaper way to approach the problem. The Global Fireball Observatory (GFO) collaboration was established in 2017 and brings together multiple institutions (from Australia, USA, Canada, Morocco, Saudi Arabia, the UK, and Argentina) to maximise the area for fireball observation time and therefore meteorite recoveries. The members have a choice to operate independently, but they can also choose to work in a fully collaborative manner with other GFO partners. This efficient approach leverages the experience gained from the Desert Fireball Network (DFN) pathfinder project in Australia. The state-of-the art technology (DFN camera systems and data reduction) and experience of the support teams is shared between all partners, freeing up time for science investigations and meteorite searching. With all networks combined together, the GFO collaboration already covers 0.6% of the Earth's surface for meteorite recovery as of mid-2019, and aims to reach 2% in the early 2020s. We estimate that after 5 years of operation, the GFO will have observed a fireball from virtually every meteorite type. This combined effort will bring new, fresh, extra-terrestrial material to the labs, yielding new insights about the formation of the Solar System