Over the Nullarbor Plain in South Australia the Desert Fireball Network detected a fireball on the night of June 1 2019 730 pm local time and 6 weeks later recovered a single meteorite 42 g named Arpu Kuilpu. This meteorite was then distributed to a consortium of collaborating institutions to be measured and analyzed by a number of methodologies including SEMEDS EPMA ICPMS gammaray spectrometry ideal gas pycnometry magnetic susceptibility measurement CT optical microscopy and accelerator and noble gas mass spectrometry techniques. These analyses revealed that Arpu Kuilpu is an unbrecciated H5 ordinary chondrite with minimal weathering W01 and minimal shock S2. The olivine and pyroxene mineral compositions in mole are Fa 19.2  0.2 and Fs 16.8  0.2 further supporting the H5 type and class. The measured oxygen isotopes are also consistent with an H chondrite SUP17SUPO  2.904  0.177 SUP18SUPO  4.163  0.336 SUP17SUPO  0.740  0.002. Ideal gas pycnometry measured bulk and grain densities of 3.66  0.02 and 3.77  0.02 g cmSUP3SUP respectively yielding a porosity of 3.0  0.7. The magnetic susceptibility of this meteorite is log   5.16  0.08. The most recent impactrelated heating event experienced by Arpu Kuilpu was measured by SUP40SUPArSUP39SUPAr chronology to be 4467  16 Ma while the cosmic ray exposure age is estimated to be between 6 and 8 Ma. The noble gas isotopes radionuclides and fireball observations all indicate that Arpu Kuilpus meteoroid was quite small maximum radius of 10 cm though more likely between 1 and 5 cm. Although this meteorite is a rather ordinary ordinary chondrite its prior orbit resembled that of a Jupiter Family Comet JFC further lending support to the assertion that many cm to msized objects on JFC orbits are asteroidal rather than cometary in origin.
['Astrophysics - Earth and Planetary Astrophysics', 'Physics - Geophysics']
The Arpu Kuilpu meteorite Indepth characterization of an H5 chondrite delivered from a Jupiter Family Comet orbit
{'The Arpu Kuilpu Meteorite: In-depth characterization of an H5 chondrite delivered from a Jupiter Family Comet orbit.': 'Seamus L. Anderson* 1 , Gretchen K. Benedix 1,2 , Belinda Godel 3 , Romain M. L. Alosius 4 , Daniela Krietsch 4 , Henner Busemann 4 , Colin Maden 4 , Jon M. Friedrich 5,6 , Lara R. McMonigal 5 , Kees C. Welten 7 , Marc W. Caffee 8,9 , Robert J. Macke 10 , Seán Cadogan 11 , Dominic H. Ryan 12 Fred Jourdan 13 , Celia Mayers 13 , Matthias Laubenstein 14 , Richard C. Greenwood 15 , Malcom P. Roberts 16 , Hadrien A. R. Devillepoix 1,17 , Eleanor K. Sansom 1,17 , Martin C. Towner 1 , Martin Cupák 1,17,18 , Philip A. Bland 1 , Lucy V. Forman 1 , John H. Fairweather 1 , Ashley F. Rogers 1 , Nicholas E. Timms 1  \n- 1 Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA, Australia.\n- 2 Dept. Earth and Planetary Sciences, Western Australian Museum, Locked Bag 49, Welshpool, WA, Australia.\n- 3 CSIRO Mineral Resources, Kensington, WA, Australia.\n- 4 Institute of Geochemistry and Petrology, ETH Zurich, CH-8092 Zurich, Switzerland.  \n- 6 Dept. of Earth and Planetary Sciences, American Museum of Natural History, 79 th Street at Central Park West, New York, NY 10024, USA.\n- 7 Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA.  \nAccepted for publication in: Meteoritics and Planetary Science (13 September 2024).', 'ABSTRACT': "Over the Nullarbor Plain in South Australia, the Desert Fireball Network detected a fireball on the night of 1 June 2019 (7:30 pm local time), and six weeks later recovered a single meteorite (42 g) named Arpu Kuilpu. This meteorite was then distributed to a consortium of collaborating institutions to be  measured  and  analyzed  by  a  number  of  methodologies  including:  SEM-EDS,  EPMA,  ICP-MS, gamma-ray  spectrometry,  ideal  gas  pycnometry,  magnetic  susceptibility  measurement ,  μCT,  optical microscopy, and accelerator and noble gas mass spectrometry techniques. These analyses revealed that Arpu Kuilpu is an unbrecciated H5 ordinary chondrite, with minimal weathering (W0-1) and minimal shock (S2). The olivine and pyroxene mineral compositions (in mol%) are Fa: 19.2 ± 0.2, and Fs: 16.8 ± 0.2, further supporting the H5 type and class. The measured oxygen isotopes are also consistent with an H chondrite (δ 17 O% = 2.904 ± 0.177; δ 18 O% = 4.163 ± 0.336; Δ 17 O% = 0.740 ± 0.002). Ideal gas pycnometry measured bulk and grain densities of 3.66 ± 0.02 and 3.77 ± 0.02 g cm -3 ,  respectively, yielding a porosity of 3.0 % ± 0.7. The magnetic susceptibility of this meteorite is log χ = 5.16 ± 0.08. The most recent impact-related heating event experienced by Arpu Kuilpu was measured by 40 Ar/ 39 Ar chronology to be 4467 ± 16 Ma, while the cosmic ray exposure age is estimated to be between 6-8 Ma. The  noble  gas  isotopes,  radionuclides,  and  fireball  observations  all  indicate  that  Arpu  Kuilpu's meteoroid was quite small (maximum radius of 10 cm, though more likely between 1-5 cm). Although this meteorite is a rather ordinary ordinary chondrite, its prior orbit resembled that of a Jupiter Family Comet (JFC) further lending support to the assertion that many cm- to m-sized objects on JFC orbits are asteroidal rather than cometary in origin.", 'INTRODUCTION': 'Although meteorites continuously fall to Earth, most lack any spatial context with regards to their orbital origin. Fireball observatory networks (Devillepoix et al. 2020; Oberst et al. 1998; TrigoRodríguez et al. 2006; and others) such as the Desert Fireball Network (DFN; Bland et al. 2012) are uniquely enabled to observe fireballs in order to calculate both their prior orbit, and the approximate landing  site  of  the  resulting  meteorite.  To  date,  54  meteorites  with  associated  orbits  have  been recovered  and  analyzed  (Meier,  2017;  see:  https://www.meteoriteorbits.info/)  in  this  effort  to  better understand how cm- to m-sized material is transferred from their asteroidal source bodies across the inner solar system. One such meteorite, Arpu Kuilpu (H5; Gattacecca et al. 2022), was observed by the DFN to fall in South Australia on 1 st June 2019 at approximately 7:30 pm local time, near the Hughes train  siding  close  to  the  border  with  Western  Australia  (Shober  et  al.  2022).  This  meteorite  was  a particularly high-priority target for recovery as it impacted Earth from a Jupiter family Comet (JFC) orbit (a=2.75 ± 0.03 AU; e=0.671 ± 0.003; i=2.03 ± 0.01 deg; Tj=2.97 ± 0.02 (Shober et al. 2022)), a rare origin for most orbitally constrained meteorites. A meteorite searching team was sent to the fall site six weeks later, recovering a single rock (42 g) on the 2 nd day. The name Arpu Kuilpu (Are-puh Kooill-puh) was provided by the traditional custodians of the area, the Maralinga people.  \nWhile the work by Shober et al. (2022) details the astronomical observations (see their Fig. 1 and  Fig.  3)  and  modelling  of  the  fireball  event  as  well  as  the  recovery  and  classification  of  the meteorite as an H5 chondrite, this work focuses primarily on the physical, chemical, geological, and chronological aspects of the meteorite itself to provide a combined history for the formation of Arpu Kuilpu within its asteroidal parent body in the early solar system, as well as its more recent ejection as a meteoroid from its contemporary source body, and how it may relate to other orbital meteorites.', 'METHODS': 'We assembled a consortium ( Table 1 ) of scientists from nearly a dozen institutions to perform a wide array of analyses to properly characterize many aspects of this meteorite.  \nTable 1 . The Arpu Kuilpu Meteorite Consortium  \n*SEM-EDS:  Scanning  Electron  Microscope-Energy  Dispersive  X-ray  Spectroscopy;  ICP-MS: Inductively  Coupled  Plasma  Mass  Spectrometry;  AMS:  Accelerator  Mass  Spectrometry;  ICP-OES: Inductively  Coupled  Plasma  Optical  Emission  Spectroscopy;  HPGe:  HyperPure  Germanium;  CRE: Cosmic Ray Exposure; AMNH: American Museum of Natural History; INFN: Italian National Institute for  Nuclear  Physics;  JdLC:  John  de  Laeter  Centre;  UWA:  University  of  Western Australia;  CSIRO: Commonwealth  Scientific  and  Industrial  Research  Organisation;  ETH:  Swiss  Federal  Institute  of Technology; CMCA: Centre for Microscopy, Characterization and Analysis.', 'HPGe Gamma-Ray Spectrometry (Short-lived Radionuclides)': 'Cosmic-ray-produced  (cosmogenic)  radionuclide  concentrations  were  analyzed  by  means  of non-destructive high purity germanium (HPGe) gamma-ray spectrometry, and the counting efficiencies have been calculated using thoroughly tested Monte Carlo codes. One specimen of Arpu Kuilpu was measured  in  the  underground  laboratories  at  the  Laboratori  Nazionali  del  Gran  Sasso  (LNGS) (Arpesella, 1996; Laubenstein, 2017) for 40.63 days (160 days after the fall date of 1 June 2019).', 'Micro XRay Computed Tomography (μCT; Bulk Density and Petrofabric Analysis)': 'The  entire  42.24  g  meteorite  was  imaged  in  3D  via  X-ray  computed  tomography  at  CSIRO Mineral Resources (Kensington, WA) using a Zeiss Versa 520 3D X-ray microscope. The instrument settings were120 kV and 10 W, producing an 11 µm voxel -1 size (3D pixel). Additionally, a 430.3 mg sub-sample was imaged at the AMNH at a resolution of 12.8 µm voxel -1 edge using polychromatic Xrays with the GE phoenix v|tome|x s μCT system operating a tungsten X-ray tube at 110 kV and 13.2 W. The AMNH µCT data were intended to be used to verify the homogeneity of the sample prior to further sub-sampling for elemental analysis; however, we examined the petrofabric texture of this subsample too.  \nTo quantitatively examine the petrofabric results, we used the same techniques as described in Friedrich et al. (2008; 2017). In short, we digitally separated the high-density Fe-Ni metal grains within the  µCT  volume  using  the  program  Blob3D  (Ketcham,  2005).  Best  fit  ellipsoids  were  constructed around the largest 5000 metal grains; next, the intersection of a line passing through the long axis of the best fit ellipsoid and a hemisphere enclosing the ellipsoid are plotted on a lower hemisphere equal area stereographic  projection.  Statistical  descriptors  of  the  fabric  tensor  eigenvalues  (Woodcock,  1977; Woodcock and Naylor, 1983; Jelinek, 1981) generated from the collective metal grain projection data and  examination  of  the  individual  best  fit  ellipsoid  shapes  using  ratios  of  the  ellipsoid  long, intermediate, and short axes (Zingg, 1935; Blott and Pye, 2008) allows for a quantitative and thorough examination  of  the  3D  petrofabric  defined  by  metal  grain  shape  preferred  orientations  within  the chondrite.', 'Scanning Electron Microscopy Energy Dispersive Spectroscopy (SEM-EDS; Meteorite Type via Mineral Phase Abundance)': 'Using the TESCAN TIMA Scanning Electron Microscope (SEM), located at the John de Laeter Centre at Curtin University, we obtained element maps of our 25 mm-diameter epoxy-mounted sample via energy dispersive spectroscopy (EDS), which used four PulsTor Energy, silicon drift, Peltier cooled detectors to collect data. Prior to this, the sample mount was polished and carbon-coated to mitigate surface charging. TIMA maps were collected using a 25 kV acceleration voltage, 6.0 nA beam current, 15 mm working distance, and 90 nm spot size. Seven element maps (Al, Ca, Fe, Cr, Mg, Si, S) were combined to create a mineral phase map using a python script (Anderson, 2023).', 'Electron Probe MicroAnalysis (EPMA; Petrologic Type via Mineral Compositions)': 'The major element compositions of olivine, orthopyroxene, and chromite in Arpu Kuilpu were measured using the JEOL 8530F Electron Probe MicroAnalyser (EPMA) at the Centre for Microscopy and  Microanalysis,  University  of  Western  Australia.  On  the  same  polished  sample  mount  used  for SEM-EDS,  we  selected  20  olivine,  20  orthopyroxene,  and  11  chromite  grains  for  elemental measurements using a beam current of 20 nA and an accelerating voltage of 15 kV. We also collected calibration measurements of our mineral standards: wollastonite (Si and Ca), periclase (Mg), magnetite (Fe), manganese metal (Mn), corundum (Al), jadeite (Na), and Durango apatite (P).', 'Optical Microscopy': 'The optical mosaic photomicrographs of the thin section, taken using the Zeiss Axio are shown in Figure  2. Further  manual  investigation  using  a  rotating  stage  revealed  both  sharp  and  undulose extinction  features  in  olivine  and  plagioclase  grains  indicating  this  meteorite  experienced  very  low shock-induced pressures or temperatures, equating to S1-S2 in the Stöffler et al. (2018) classification scheme. No opaque shock veins or mosaicism were observed, eliminating the possibility for localized S3 shock or higher.  \nFigure 2. Cross-polarized image of our Arpu Kuilpu thin section, which clearly shows a texture consistent with an equilibrated H chondrite. Further investigation of this thin section under a rotating stage reveals undulose light extinction in olivine and plagioclase grains, indicating a low-pressure shock history (S 1-2; Stöffler et al. 2018).  \n<!-- image -->', 'Mössbauer Spectroscopy (Weathering State)': 'The spectrum of the Arpu Kuilpu meteorite sample shown in Figure 3 is dominated by a pair of peaks at ∼ 0 mm/s and +2.5 mm/s. This wide split doublet, offset to positive velocities, is characteristic of  a  ferrous  (Fe2+)  mineral.  The  distance  between  the  lines  is  the  quadrupole  splitting  (QS)  and  is associated with an electric field gradient at the iron site in the mineral, while the center of the doublet (arithmetic mean of the two peak positions) is the isomer shift (IS). Closer inspection of the two peaks reveals that each of the lines has a second, weaker line associated with it and these two weaker lines are due to a second Fe2+ mineral. The fitted values of the QS and IS for these components, given in Table 3,  allow  them  to  be  identified  as  arising  from  Olivine  and  Pyroxene,  with  the  former  mineral  being about twice as abundant as the latter (Dyar et al., 2006).  \nTo the left and right of the primary doublets there are a series of weaker peaks. These are due to the presence of two magnetic minerals: Fe-Ni metal, and Troilite. As with Olivine and Pyroxene, the two magnetic minerals are identified using the fitted parameters (IS, QS and hyperfine field) shown in  \nTable 3. Finally, we observed a weak ferric component in the spectrum that accounted for ∼ 2% of the total area and is attributed to paramagnetic nanoparticles. The results of the Mössbauer analysis show little  terrestrial  alteration,  as  any  Fe 3+ signal  in  an  ordinary  chondrite  (which  is  quite  low  for Arpu Kuilpu) would originate only from terrestrial alteration.  \nTable 3. The  values  of  Isomer  Shift  (I.S.),  and  Quadrupole  Splitter  (Q.S).  for  subspectra  #1  and  #2 indicate  Fe 2+ and  are  assigned  to  olivine  and  pyroxene,  respectively.  Subspectrum  #3  indicates  Fe 3+ paramagnetic  nanoparticles  (n-p-3+).  Component  #4  is  a  magnetic  sextet  with  small  I.S.  and  Q.S. values,  and  a  magnetic  Hyperfine  Field  (H.F.F.)  of  33.59 T  indicating  Fe  metal.  Component  #5  is  a magnetic sextet whose I.S. and H.F.F. values indicate Troilite.Kuilpu meteorite RT 98 Arpu  \nArpu Kuilpu meteorite RT  \n<!-- image -->  \nFigure 3 . The Mössbauer spectrum of Arpu Kuilpu (top) and the fitting difference (bottom), note the dramatically different vertical scales.  \n<!-- image -->', 'Inductively Coupled Plasma Mass Spectrometry (ICP-MS; Bulk Major and Trace Element Geochemistry)': 'We performed elemental analysis on three chips of Arpu Kuilpu (103.3, 107.8, 128.1 mg) at the Chemistry Department of Fordham University. We first ground each chip in an agate mortar and pestle. To dissolve the powders, we used a combination of HF and HNO3 in a high pressure CEM Mars 5 microwave digestion system, dried the resulting mixture to incipient dryness on a hotplate, treated the residue with HClO4, and again brought it to incipient dryness to dissolve the samples. In addition to the Arpu Kuilpu samples, a procedural blank and the Allende Standard Reference Meteorite were taken up in 1% HNO3 and analyzed with a ThermoElemental X-Series II ICPMS with the methods outlined in Friedrich et al. (2003) for trace elements, and Wolf et al. (2012) for major and minor elements. For examination  of  the  data,  we  compare  them  with  Orgueil  CI  chondrite  values  from  Friedrich  et  al. (2002) for trace elements and the compiled Orgueil results of Anders and Grevesse (1989) for major and minor elements.', 'Oxygen Isotopes': 'The oxygen isotope ratios measured in Arpu Kuilpu can be seen in Figure 5 and are as follows (all with 1σ uncertainties): δ 17 O% = 2.904 ± 0.177; δ 18 O% = 4.163 ± 0.336; Δ 17 O% = 0.740 ± 0.002.  \nFigure 5. The oxygen isotope composition of Arpu Kuilpu plotted in the context of other ordinary chondrites (data sourced from Clayton et al. (1991)), clearly showing that this meteorite is an H chondrite.  \n<!-- image -->', 'Laser Scanning and Ideal Gas Pycnometry (Density and Porosity)': 'A 14.64 g piece of Arpu Kuilpu was used for the determination of bulk and grain density, as well  as  porosity.  Bulk  volume  was  measured  with  NextEngine  model  2020i  ScannerHDPro  laser scanner with a rotating platform (Macke et al. 2015). Scans were performed at 16k dots per inch (dpi). For each of the three possible orientations of the meteorite, 16 scans were performed, with the platform rotated 1/16 of a complete circle between each scan. Scans were trimmed of artifacts and aligned to construct a "watertight" computer model of the specimen, from which we calculated the bulk volume. Grain volume was measured via ideal gas pycnometry with a Quantachrome Ultrapycnometer 1000, using gaseous nitrogen. The measurement procedure was run 15 times, of which the average of the last 6 were taken as the grain volume of the specimen, consistent with the technique described in Macke (2010). Porosity (P) was calculated from the bulk and grain densities (ρ): P = 1 ρ bulk /ρ grain', 'Magnetic Susceptibility': 'The magnetic susceptibility measured from Arpu Kuilpu is log χ = 5.16 ± 0.08 (log SI units), consistent with other H chondrites (Consolmagno et al. 2006; Macke et al. 2011).', 'Cosmogenic Radionuclides (Cosmic Ray Exposure)': "We prepared samples by using a ~0.24 g chip of Arpu Kuilpu for analysis of the cosmogenic radionuclides 10 Be (half-life=1.36 × 10 6 yr), 26 Al (7.05 × 10 5 yr) and 36 Cl (3.01 × 10 5 yr), following the procedures described in Welten et al. (2011). We crushed the sample in an agate mortar and separated the  magnetic (metal) from the non-magnetic (stone) fraction. The magnetic fraction was purified by ultrasonic  agitation  in  0.2N  HCl  to  remove  attached  troilite. After  rinsing  the  metal  four  times  with MilliQ water and once with ethanol, we obtained 33 mg of relatively clean metal, corresponding to 13.9 wt% bulk metal. The metal fraction was further purified by ultrasonic agitation in concentrated HF for  15  min  to  dissolve  attached  silicates. We  dissolved  32  mg  of  the  purified  metal  in  ~10%  HNO3 along with a carrier solution containing 0.90 mg Be, 1.01 mg Al, and 2.99 mg Cl. After dissolution, we took  a  small  aliquot  (~5.5%)  of  the  dissolved  sample  for  chemical  analysis  and  used  the  remaining solution for cosmogenic radionuclide analysis. We also dissolved 96 mg of the stone fraction of Arpu Kuilpu,  along  with  3.19  mg  of  Be  carrier  and  2.77  mg  of  Cl  carrier,  in  concentrated  HF/HNO3  by heating the mixture for 24 h inside a Parr Teflon digestion bomb at 125 °C. After cooling the sample to room temperature, we separated the Cl fraction as AgCl, and removed Si in the solution by repeatedly fuming the sample to dryness with HClO4. The residue was dissolved in dilute HCl and a small aliquot (3.4%) was taken for chemical analysis. After adding ~5.0 mg of additional Al carrier to the remaining solution, we separated the Be and Al fraction for radionuclide analysis.  \nAfter  separating  and  purifying  the  Be, Al  and  Cl  fractions,  the 10 Be/Be, 26 Al/Al  and 36 Cl/Cl ratios of the samples, blanks and standards were measured by Accelerator Mass Spectrometry (AMS) at Purdue University's PRIME Lab (Sharma et al. 2000). The measured ratios were normalized to those of well-known  AMS  standards  (Nishiizumi  2004;  Nishiizumi  et  al.  2007;  Sharma  et  al.  1990)  and converted to concentrations in disintegrations per minute per kg (dpm/kg).  \nFor the chemical analysis, we made two consecutive dilutions of the aliquots of the dissolved metal and stone fractions for characterization by ICP-OES. All dilutions were measured on a Thermo Fisher iCAP 6300 duo instrument.", 'Noble Gas Composition (Cosmic Ray Exposure, Meteoroid size and Sample Shielding, Gas Retention Age)': "Measurements of  all  stable  noble  gas  isotopes  (He,  Ne, Ar,  Kr,  Xe)  were  performed  on  two aliquots (29.267 ± 0.015 mg (AKL) and 27.178 ± 0.014 mg (AKS)) of Arpu Kuilpu. The samples were first wrapped in aluminum foil and heated at 110°C in ultra-high vacuum for several days to remove adsorbed atmospheric gases. The measurements were carried out on the in-house-built noble gas mass spectrometer 'Albatros' at ETH Zürich, using the procedures described in detail in Riebe et al. (2017). Gas extraction was achieved by melting the samples in a Mo crucible at ~1700 °C for ~25 min. The blank corrections for both aliquots are <1.5% of the He and Ne isotope signals, and <2.5% for Ar. The corrections for all Kr isotopes were < 7% of the signals, and < 2% for all Xe isotopes.  \nWe  numerically  separated  the  cosmogenic  (cos)  and  trapped  (tr)  components  using  a  twocomponent  deconvolution  between  ( 36 Ar/ 38 Ar)cos  (0.63-0.67;  Wieler,  2002)  and  ( 36 Ar/ 38 Ar)tr.  The trapped component used for the deconvolution was delimited by the values for Q and air (5.32-5.34; Busemann et al. 2000; Nier, 1950) since no solar wind component was detected for He and Ne.  \nTo  constrain  the  CRE  age  from  noble  gas  data,  we  calculated  the  production  rates  of cosmogenic 3 He, 21 Ne,  and 38 Ar  based  on  the  model  for  ordinary  chondrites  from  Leya  &  Masarik (2009), which considers the pre-atmospheric size of the meteoroid, the depth of the sample within the meteoroid, and the bulk chemical composition of the sample. Where possible, we used the elemental concentrations reported by the ICP-MS portion of this study in these model calculations. For elements not measured in this study (via ICP-MS) we used data for H chondrites from the literature (Si and S from Alexander, 2019; C from Lodders and Fegley, 1998; while O was calculated for the sum of all concentrations to reach 100 wt%). Since the original observations of the fireball (Shober et al. 2022) suggest a pre-atmospheric meteoroid size of ~5 cm, we used a modified version (Wieler et al. 2016) of the Leya and Masarik (2009) model, which considers small (<7 cm) H chondrite meteoroids. Ratios of cosmogenic  noble  gases,  specifically  the  cosmogenic 22 Ne/ 21 Ne  ratio  can  be  used  as  a  shielding indicator to then calculate the size of the original meteoroid and the meteorite's burial depth within it, which  is  required  to  determine  production  rates  and  CRE  age.  Consistent  with  the  small  preatmospheric meteoroid size assessed independently, only the modified model for small H chondritic meteoroids  (Wieler  et  al.  2016)  revealed  matches  between  prediction  and  the  measured  high cosmogenic 22 Ne/ 21 Ne ratios.  \nGas retention ages  for both aliquots were  calculated separately using the U/Th-He and  K-Ar chronometers with the U, Th, and K concentrations from the Gamma-Ray Spectrometry portion of this study.  The 4 Herad  values  for  the  U/Th-He  chronometer  were  calculated  by  assuming  that  the 3 He concentrations were cosmogenic, and applying a ( 4 He/ 3 He)cos ratio between 5.2 and 6.1 (Wieler, 2002). The 4 Hecos concentration was then subtracted from our measured 4 He concentration (with 4 Hetr being negligible). The 40 Arrad values for the K-Ar chronometer were calculated with the deconvoluted 36 Artr, adopting a ratio ( 40 Ar/ 36 Ar)tr between 0 and 295.5 (covering Q and air composition; Busemann et al. 2000; Steiger and Jäger, 1977).", '40 Ar/ 39 Ar Chronology (Thermal and Impact History)': 'To determine the 40 Ar/ 39 Ar chronology, we crushed a whole rock fragment from Arpu Kuilpu and selected nine pyroxene aliquots each including between 1 and 30 grains, and with each grain ranging in size from 150 to 350 µm in diameter. We also selected a single plagioclase grain . The samples were irradiated for 40 hours, then analyzed at the Western Australian Argon Isotope Facility at Curtin University using a ARGUS VI Mass Spectrometer, using a 10.4 µm CO2 laser to affect step heating for 60 sec. The complete procedure is similar to the one described by Jourdan et al. (2020) for other meteorite samples.', 'SEM-EDS (Meteorite Class and Texture)': "The mineral map produced by SEM-EDS imaging is shown in Figure 1 , and clearly reveals a texture  consistent  with  an  equilibrated  ordinary  chondrite,  consisting  of  Fe-Ni  metal  (kamacite  and taenite),  chromite,  troilite,  plagioclase  and  Ca-phosphate  grains,  as  well  as  olivine  and  pyroxene chondrules, all set within a recrystallized, mostly silicate matrix. There are recognizable chondrules, though they have fairly indistinct boundaries separating them from the matrix.  \nFigure 1. A false color mineral map of Arpu Kuilpu's epoxy -mounted thick section taken from SEMEDS data (initially appearing as Fig. 9 in Shober et al. 2022), which clearly shows a texture typical of an equilibrated ordinary chondrite. The large void on the right is an artifact of the polishing step when a remnant chondrule was likely and unintentionally removed.  \n<!-- image -->", 'EPMA (Electron Probe MicroAnalysis; Mineral Compositions)': "The  full  dataset  from  the  EPMA  is  displayed  in Table  2. The  olivine  compositions  of Arpu Kuilpu average at fayalite = 19.2 ± 0.2 mol% (n=20), while the orthopyroxenes reside at ferrosilite = 16.8 ± 0.2 mol% and wollastonite = 1.4 ± 0.2 mol% (n=20). The chromite compositions are: Cr/(Cr + Al) = 85.5 ± 0.3, and Fe/(Fe + Mg) = 84.4 ± 1.2 (n=11). The olivine and pyroxene compositions reveal that Arpu Kuilpu is an H chondrite (Van Schmus and Wood, 1967), while the Wo value of 1.4 indicates a petrologic type 5 (Scott et al. 1986). All uncertainties listed above are 1σ.  \nTable 2. EPMA measurements of Arpu Kuilpu's Olivines, Orthopyroxenes, and Chromites . Oxides concentrations are displayed in wt%.", 'ICP-MS (Bulk Major and Trace Element Analysis)': "The  50  major,  minor,  and  trace  elements  measured  via  ICP-MS  are  shown  in Table  4 .  The higher inter-aliquot variability of the light REE may be due to one of the aliquots being very slightly enriched in phosphates or having an unrepresentative pyroxene/plagioclase ratio relative to the whole sample (Mason and Graham, 1970). The Fe, Ni, and Co abundances normalized to CI and Mg ( Figure 4 )  of  Arpu  Kuilpu  are  more  consistent  with  what  would  be  expected  for  an  H  chondrite  than  the  \nTable  4 .  Abundances  of  50  elements  in  the  Arpu  Kuilpu  chondrite. Errors, given as percent relative standard deviation (%RSD), are ≤14.0% for all elements except for the light Rare Earth Elements La, Ce, Pr, Nd, and Sm, where all had %RSD values between 16.5-17.6 based on the three replicate aliquots analyzed. Other more variable elements include Re  (17.6%),  Ir  (25.0%),  Sn  (20.0%),  Cu  (21.2%),  As  (16.6%),  Sb (37.9%).  \nsiderophile  trace  elements  Re,  Ir,  Mo,  Pt,  and  Pd  which  are  all  nearly 40% higher  in  abundance  (normalized  to  CI  and  Mg)  than  the  major elements  Fe  and  Ni.  Perhaps  we  are  seeing  a  refractory  siderophile nugget  affecting  enrichment  of  the  refractory  siderophile  elements within our analyzed aliquots.  \nFigure  4 .  The  bulk  elemental  concentrations  of  the Arpu  Kuilpu  meteorite,  measured  via  ICP-MS, normalized  to  Magnesium  and  CI  chondrite  abundances.  The  top  plot  shows  most  of  the  lithophile elements,  which  have  a  mean  and 1  σ  normalized  abundance  of  0.91  ±  0.07,  with  the  dotted  line representing  the  0.9  mean  lithophile  abundance  observed  in  ordinary  chondrites  (Kallemeyn  et  al., 1989). The bottom plot displays Arpu Kuilpu's siderophile elemental concentrations (left, Re -Pd), as well  as  a  few  other  lithophile  and  chalcophile  abundances.  The  three  dotted  lines,  represent  the normalized  mean  siderophile  abundances  for  H,  L,  and  LL  chondrites  reported  in  Kallemeyn  et  al. (1989), which for Arpu Kuilpu is 1.42 ± 0.23, closest to that of H chondrites.  \n<!-- image -->", 'Laser Scanning and Ideal Gas Pycnometry': 'We measured the bulk density of the 14.64 g sample of Arpu Kuilpu to be 3.66 ± 0.02 g cm -3 , and a grain density of 3.77 ± 0.02 g cm -3 .  These data taken together yield a porosity of 3.0 % ± 0.7, which is typical of ordinary chondrites (Britt and Consolmagno, 2003).', 'Micro X-Ray Computed Tomography Bulk Density': "Using the μCT data from the 430.3 mg piece, we measured the subsample's volume to be 118.5 mm 3 , yielding a bulk density of 3.63 g cm -3 which is in good agreement with the 3.66 g cm -3 found by laser  scanning  and  Ideal  Gas  Pycnometry  of  a  separate  aliquot  (see  above).  This  indicates  that  the sample  is  relatively  homogeneous  at  the  0.1-10  cm 3 scale.  Visual  inspection  of  the  tomography volumes confirms this observation. These bulk densities are consistent with the average H chondrite fall bulk density of 3.42 ± 0.19 g cm -3 (Consolmagno et al. 2008).", 'Petrofabric and Shock State': "A  typical  µCT  'slice'  of  the  Arpu  Kuilpu  ordinary  chondrite  is  shown  in Figure  6 .  The petrofabric, as defined by the metal grain shape preferred orientations (see methods), of Arpu Kuilpu shows  the  major  axes  of  the  grains  define  a  relatively  indistinct  girdle  and  the  minor  axes  cluster weakly at high angles to the major axis girdle ( Figure 7) . Together these features are the signature of a foliation  petrofabric.  It  is  generally  agreed  that  foliation  petrofabrics  in  chondrites  are  the  result  of grain rotation and alignment during uniaxial hypervelocity impact deformation (Gattacceca et al. 2005; Friedrich et al. 2008).  \nFigure 6 . μCT 'slice' of a chip of the Arpu Kuilpu ordinary chondrite. The higher the greyscale value, the higher the average atomic weight of the material. The bright white Fe-Ni metal grains and pale grey Fe sulfides can be  easily  distinguished  from  the  moderate grey  silicates  and  the  air  around  the  chip represented  as  black.  Although  small  cracks  can  occasionally  be  seen,  there  is  no  evidence  of brecciation.  \n<!-- image -->  \nExamination  of  the  eigenvalue  tensor  fabric  descriptors  shows  that  the  major  axis  shape parameter (Kmajor = 0.73) indicates a girdle distribution (K<1) (also see Figure 7 ). The minor axis shape parameter (Kminor = 1.401) can be classified as a cluster distribution (K>1). Both of these parameters agree with visual inspection of the fabric. The major axis anisotropy parameter has a value of 0.071. It is  known  that  the  fabric  anisotropy  varies  in  intensity  with  increasing  petrographic  shock  stage (Friedrich et al. 2008; Friedrich et al. 2017). Based on an anisotropy of 0.071, a best estimate for the shock  stage  (Stöffler  et  al.  2018)  of  the  sample  may  be  S1  to  S2,  which  matches  with  other microstructural features observed in the thin section. We also examined the anisotropy of the fabric of the largest 1000 grains in the smaller 435 mg sample collected with a different CT instrument and at a different  spatial  resolution.  The  anisotropy  parameter  for  this  sample  was  strikingly  similar  with  a value of 0.073.  \nFigure 7 .  Stereoplots  and  densities  of  orientations  of  the  major  and  minor axis  of best  fit  ellipsoids around the largest 5000 metal grains in the Arpu Kuilpu ordinary chondrite. Arpu Kuilpu ' s major axis fabric is a relatively indistinct girdle and the minor axis is a cluster, together being the signature of a very weak foliation petrofabric.  \n<!-- image -->  \nThe shapes of the digitally constructed best-fit ellipsoids digitally constructed around the largest 5000 metal grains in Arpu Kuilpu are shown in Table 5 . Of the metallic grains, 35.7 % have sub-equant spheroid shapes (see Blott and Pye, 2008 for shape descriptors) with the next most abundant (31.6 %) being  prolate  spheroids.  Oblate  spheroid  grains  (16.4%)  make  up  the  largest  remaining  category  of metal grain shapes.  \nTable 5. Shapes of largest 5000 metal grains in the Arpu Kuilpu chondrite  \nIn Figure 8 , we place the physical properties porosity and fabric anisotropy of the Arpu Kuilpu into the context of other ordinary chondrites. Arpu Kuilpu falls into a region of very low porosity, but also very low fabric anisotropy that is indicative of high ambient heat during or after the minor shock pressure that Arpu Kuilpu experienced (see Friedrich et al. 2017).  \nFigure 8. Plot of porosity versus petrofabric anisotropy for typical ordinary chondrites and a suite of low-shock, low-porosity,  low-foliation  ordinary  chondrites  (data  from  Friedrich  et  al.  2017)  and  the Arpu Kuilpu ordinary chondrite. Errors of these measured values are shown for selected samples to give the reader an idea of the typical magnitude of the associated errors. Arpu Kuilpu falls into a region of very low porosity, but also very low fabric anisotropy, indicative of the sample having experienced high ambient heat during or after the impact-related shock that has affected this meteorite.  \n<!-- image -->", 'Gamma-Ray Spectrometry': 'The results from the gamma-ray spectrometry measurements displayed in Table 6 were briefly mentioned by Shober et al. (2022) but are re-presented here for clarity. The main conclusion of Shober et al. (2022) was that the low 60 Co activity (0.8 ± 0.3 dpm kg -1 ) indicated that the original meteoroid was small enough (~10 cm; Bonino et al. 2001) that its recent cosmic-ray exposure in space did not produce  a  significant  flux  of  thermal  neutrons.  The  measured 26 Al  activity  using  this  method  is consistent  with  a  small  H  chondrite  (Bhandari  et  al.  1989;  Bonino  et  al.  2001;  Leya  and  Masarik, 2009),  and  with  the AMS  measurements  (see  below)  of 26 Al.  Considering  the  time  of  measurement (183 days after the fireball event) the activities are consistent with a rock that stopped accumulating cosmogenic radionuclides on 1 June 2019.  \nTable 6. Massic activities (corrected to date of fall of the meteorite 1 st June 2019) of cosmogenic and primordial  radionuclides  in  the  specimen  of  the  Arpu  Kuilpu  stone  measured  by  non-destructive gamma-ray spectrometry. Errors include a 1 σ uncertainty of 10% in the detector efficiency calibration.  \nWhen we compare the radionuclide concentrations with cosmic ray production estimations for 26 Al (Leya and Masarik, 2009), 60 Co (Eberhardt et al. 1963, Spergel et al. 1986), 54 Mn (Kohman and Bender,  1967),  and 22 Na  (Bhandari  et  al.  1993),  and  assume  the  specimen  is  from  the  central  part (which may not be a reliable assumption, see Discussion), the best  agreements  are  obtained  (in  the sequence of the given isotopes) for radii of < 10 cm, < 20 cm, < 5 cm and 5-8 cm. The 22 Na/ 26 Al ratio for this specimen is 1.9 ± 0.2. Combining these results of these radionuclides, we infer a radius of 5 to 10 cm, for a roughly spherical meteoroid. Alternatively, it can be from the surface (<5 cm) of a larger meteoroid.  \nThe  concentrations  of  U,  Th,  and  K,  derived  from  the  activities  of  the  naturally  occurring nuclides ( 235 U, 238 U, 232 Th, 40 K; Table 6) are consistent with average concentrations in H chondrites (Wasson and Kallemeyn, 1988).', 'Long-lived Cosmogenic Radionuclides (AMS and ICP-OES)': "In  general,  the  bulk  composition  of  the  Arpu  Kuilpu  sample  that  was  used  for  cosmogenic radionuclide  analysis  (measured  via  ICP-OES,  see Table  7 )  is  consistent  with  both  the  average  H chondrite composition of Wasson and Kallemeyn (1988), and with the measurements made via ICP-MS (see above). The Co and Ni concentrations in the metal fraction of Arpu Kuilpu are consistent with H chondrite  classification,  while  the  Mg  concentration  of  <10  ppm  indicates  that  the  purified  metal contained  no  detectable  (<0.01  wt%)  silicate  contamination.  This  implies  that 10 Be  and 26 Al contributions  from  silicates  are  negligible  and  thus  that  the  measured 10 Be  and 26 Al  concentrations require no correction.  \nTable 7. Chemical composition of metal and stone fractions of Arpu Kuilpu. All values are in wt %. The bulk composition (ICP-OES) is calculated from measured values in metal and stone fractions, which are 13.9 and 86.1 wt%, respectively. The ICP-MS measurements (see Table 4) are repeated here for comparison. The last column shows average H chondrite composition from Wasson and Kallemeyn (1988). Entries 'nm' indicate not measured.  \nThe  results  of  the  AMS  measurements  of  Arpu  Kuilpu  are  shown  in Table  8. The  high concentrations of 10 Be and 26 Al in the metal phase as well as the 26 Al/ 10 Be ratio of 0.77 ± 0.03 indicate that the Arpu Kuilpu meteorite had a minimum CRE age of 4-6 Myr in a relatively small object (radius < 10 cm).  \nTable 8 . Cosmogenic radionuclide concentrations (in dpm/kg) in the metal and stone fractions of Arpu Kuilpu. The bulk values are calculated from the metal and stone based on measured metal and stone proportions  of  13.9  and  86.1  wt%,  respectively.  The  last  column  shows  the 10 Be(sto)/ 10 Be(met) and 26 Al(sto)/ 26 Al(met) ratios, which can be used as a shielding indicator (see Discussion).", 'Noble Gas Isotopes': "The measured concentrations and ratios of the noble gases in Arpu Kuilpu are listed in Table 9. Both He and Ne are purely cosmogenic (cos) apart from 4 He. The non-cosmogenic fraction of the 4 He signal  is  assumed  to  be  radiogenic  (rad),  which  is  supported  by  the  Ne  isotope  values  that  do  not indicate the presence of a trapped (tr) component. A solar wind component could therefore be excluded, which  also  rules  out  the  possibility  of  this  meteorite  being  a  regolith  breccia.  The  absence  of primordially trapped He is likely caused by thermal processing at temperatures going up to ~740 °C for H5 chondrites (olivine -spinel equilibrium temperature, Kessel et al. 2007).  \nThe 36 Ar/ 38 Ar values for both samples (3.28 ± 0.02 for AKS and 2.73 ± 0.02 for AKL) do not match pure cosmogenic compositions (0.63-0.67; Wieler, 2002) and imply mixing between trapped (tr) and cosmogenic (cos) Ar. The trapped component cannot be identified since the isotopic compositions Q and air 36 Ar/ 38 Ar ratios are too close to each other. Although a small cosmogenic component can be observed in 38 Ar, it can neither be recognized in the 78 Kr/ 84 Kr and 80 Kr/ 84 Kr ratios nor in the light Xe  \nisotopes.  Both  measured  aliquots  display  high 129 Xe/ 132 Xe  ratios  resulting  from  a  short-lived 129 Iderived 129 Xe excess, a feature commonly observed in OCs of types 5 or 6 (e.g. Alaerts et al. 1979; Moniot, 1980), fitting with Arpu Kuilpu's H5 petrologic type.  \nTable 9. The noble gas isotopic concentrations and ratios of the two measured aliquots from Arpu Kuilpu (AKL and AKS; 84 Kr = 100; 132 Xe = 100).  \nTable 10. Radiogenic concentrations of He and Ar (in 10 -8 cm 3 STP/g), and gas retention ages (T4 and T40) calculated using U, K, and Th concentrations from the Gamma-ray spectroscopy section of this study (see Table 6 ).  \nThe U/Th-He and K-Ar chronometers for both aliquots yield old gas retention ages around 4.04.6 Gyr essentially within the same range ( Table 10 ), suggesting no major resetting events in Arpu Kuilpu's history.  \nThe production rates of cosmogenic 3 He, 21 Ne and 38 Ar calculated with the above-mentioned model and the resulting CRE ages of the two aliquots are given in Table 11 . The T3, T21 and T38 ages are comparable, with the T21 and T38 ages overlapping within their ranges for AKS. The T3 ages for both aliquots overlap with each other and are lower than the T21 and T38 ages. The T21 age for AKL is slightly  higher  than  for  AKS.  This  discrepancy  could  stem  from  a  difference  in  exposure  to  solar  \ncosmic rays (SCR) which can affect material in the upper few cm of a meteoroid. While the 22 Ne/ 21 Ne ratios  of  both  aliquots  suggest  a  pre-atmospheric  radius  of  the  meteoroid  of  1  cm  according  to  the model, the sample depth of AKL is shallower, which might have resulted in a slightly higher SCRderived 21 Necos production ( Table 11 ). Due to this possibility, the T21 age for AKL of ~10 Myr is not used as the maximum for our preferred CRE age. The ( 3 He/ 21 Ne)cos and ( 21 Ne/ 22 Ne)cos ratios of AKS and AKL do not indicate significant 3 He loss. According to the cosmogenic noble gas concentrations, the CRE age for Arpu Kuilpu is ~7-9 Myr ( Table 11 ).  \nTable 11. Suitable shielding conditions matching our cosmogenic 21 Ne/ 22 Ne value (average for AKS and AKL: 0.772 ± 0.006), determined with the model by Leya and Masarik (2009) updated for small H chondrite meteoroids (Wieler et al. 2016), cosmogenic 3 He, 21 Ne and 38 Ar isotope concentrations (in 10 -8 cm 3 STP/g), production rates Px (in 10 -8 cm 3 /(g × Myr)), and calculated CRE ages Tx (in Myr).", '40 Ar/ 39 Ar Chronology': 'We selected  nine  pyroxene  aliquots  including  between  1  and  30  grains,  and  with  each  grain ranging  in  size  from  150-350  µm  in  diameter,  along  with  one  plagioclase  grain  for 40 Ar/ 39 Ar chronology. Seven pyroxene aliquots yielded statistically indistinguishable plateau ages ranging from 4409 ± 71 Ma and 4501 ± 178 Ma ( Figure 9B ) and their combined ages result in a weighted mean age of 4467 ± 16 Ma ( Figure 9A ; P = 0.16; 2σ). Two single grain pyroxene analysis yielded plateau age of 4251  ±  163  Ma  and  4310  ±  135  Ma  slightly  younger  than  the  pyroxene  bulk  population.  The plagioclase analysis did not yield enough gas for a successful analysis.  \nFigure 9. (A)  Example  of  a  plateau  age  (2σ)  obtained  for  one  (Hughes  30GRN  150u  pyxB)  of  the seven  pyroxene  aliquots  extracted  from  the Arpu  Kuilpu  meteorite.  (B)  Weighted  mean  age  of  the seven plateau ages obtained on pyroxene populations.  \n<!-- image -->', 'Meteorite Class and Type': 'Every  relevant  analysis  we  have  performed  on  this  meteorite  confirms  that  Arpu  Kuilpu  is indeed  an  H5  ordinary  chondrite.  Gamma-Ray  spectrometry,  µCT,  oxygen  isotopes,  ICP-MS,  ICPOES,  Mössbauer  spectroscopy,  ideal  gas  pycnometry,  and  magnetic  susceptibility,  each  indicate  the general  H  chondrite  meteorite  class,  while  results  from  the  SEM-EDS  ( Figure  1) and  optical microscopy ( Figure 2) analyses reveal a texture consistent with a petrologic type 5, further confirmed by the EPMA measurements of individual mineral compositions. The lack of trapped noble gasses also excludes the possibility for lower (3 or 4) petrologic types.', 'Weathering': 'Arpu  Kuilpu  was  recovered  approximately  six  weeks  after  its  fall,  and  although  8.4  mm  of rainfall was recorded at the nearest weather station at Forrest Airport in Western Australia between its fall  and  recovery  (Shober  et  al.  2022),  visual  inspection  of  the  meteorite  did  not  reveal  significant weathering. Inspection of the thin section via optical microscopy also reveals little terrestrial alteration, all  of  which  is  also  supported  by  a  very  minor  Fe 3+ signal  from  the  Mössbauer  spectroscopy measurements ( Table 3; Figure 3 ).', 'Shock State and Impact History': 'The traditional method of determining the shock stage in meteorites, optical microscopy, has revealed  that  Arpu  Kuilpu  experienced  relatively  little  shock  (S1-S2;  Stöffler  et  al.  2018).  This  is further supported by petrofabric measurements taken from the μCT data (Friedrich et al. 2008; 2017), seen in Figure 7 . By combining the major axis anisotropy value of C = 0.071 with the porosity of 3.0 ± 0.7% (measured via ideal gas pycnometry), as seen in Figure 8 , Arpu Kuilpu likely experienced high ambient heat at approximately the same time that it underwent its minor impact induced shock. The results of the 40 Ar/ 39 Ar experiments precisely constrain the latest possible time for such an impact event  \nto the very early solar system at 4467 ± 16 Ma, which is also supported by old ages (> 4.0 Gyr) from the  noble  gas  analysis  via  U/Th-He  dating,  further  ruling  out  the  possibility  for  recent  impacts  (see Table 10 ).  \nNote  that  the 40 Ar/ 39 Ar  systematic  in  pyroxene  is  relatively  easy  to  reset  and  even  minor impacts can produce enough energy to reset pyroxene provided that the shock wave creates a spike of high temperature for duration as short as few micro-seconds (Cassata et al., 2011; Kennedy et al., 2019; Jourdan et al., 2020), which in the present case, would be exacerbated by a high ambient heat. Minor subsequent impacts might have been recorded by individual crystals of pyroxene at 4251 ± 163 Ma and 4310 ± 135 Ma, but considering that these two ages are isolated, the shock event might have been very small with very focused energy, not sufficient to affect the majority of the pyroxene crystals.', 'Meteoroid Size, Burial Depth, and CRE Age': "Determining the irradiation depth of Arpu Kuilpu within its original meteoroid, as well as the meteoroid's  size,  and  CRE  age,  requires  the  insight  of  three  methodologies  employed  in  this  study: gamma-ray spectrometry, AMS, and noble gas analysis, as well as the fireball observations presented in Shober et al. (2022). For the pre-atmospheric size of the meteorite, each method provides an estimate based on a different time interval, with the fireball data representing the size at the time of atmospheric entry,  the  short-lived  radionuclides  the  size  during  the  past  few  years  before  entry,  the  long-lived radionuclide the size of the past few million years before entry and the noble gases the average size during  its  entire  cosmic-ray  exposure.  For  a  meteorite  with  a  simple  CRE  history,  i.e.,  with  no significant  changes  in  size  during  CRE,  all  four  estimates  should  yield  the  same  size  within  the uncertainties of each method and the model calculations associated with it.  \nThe  first  calculation  of Arpu  Kuilpu's  original  size  as  a  meteoroid  is  given  in  Shober  et  al. (2022),  where  a  pre-atmospheric  size  of  approximately  5  cm  (radius)  is  derived  from  the  fireball observations, though this size estimate is prone to variation due to uncertainties in model parameters such as shape and spin of the meteoroid which are assumed values. Arpu Kuilpu's atmospheric entry was also observed to have experienced a fragmentation event near the end of the fireball (Shober et al. 2022), further opening the possibility that the meteorite could have come from a non-central part of the meteoroid.  \nThe results  of  the  non-destructive  HPGe  Gamma-Ray  Spectrometry  measurements  ( Table 6) also support a small meteoroid size between 5-10 cm (assuming a spherical meteoroid). The activities of the short-lived radioisotopes, with half-lives that are less than the orbital period ( Table 6 ), represent the production integrated over the last segment of the orbit. The fall of Arpu Kuilpu occurred during a minimum at the end of solar cycle 24, as indicated by the neutron monitor data (Bartol, 2020). The cosmic ray flux was high in the six months before the fall, so the activities for the very short-lived radionuclides are expected to be high, as earlier reported (Jenniskens et al. 2014 and references cited therein; see Table 6 ).  \nAs discussed in the methods, the 22 Ne/ 21 Ne ratio can be used as a shielding factor to estimate the size of the original meteoroid, the cosmogenic noble gas production rates, and the meteorite's depth within the meteoroid. For Arpu Kuilpu's two analyzed aliquots, the 22 Ne/ 21 Ne ratios nearly agree within error (~1.28; see Table 9 ), and are relatively high, suggesting a solar cosmic ray (SCR) component. As stated  in  the  Methods  and  Results  sections,  these  high 22 Ne/ 21 Ne  ratios  yielded  no  matches  for meteoroids 10-500 cm  when using the model from Leya and Masarik (2009), so we instead used a modified version of this model (Wieler et al. 2016) intended for a meteoroid radius up to 7 cm, which yields a very small meteoroid radius (~1 cm), and an even shallower burial depth (<1 cm) for Arpu Kuilpu.  Considering  the  modeled  production  rates  of 3 He, 21 Ne,  and 38 Ar ( Table 11 ),  the  noble  gas content suggests a CRE age of ~7-9 Ma.  \nThe AMS-measured concentrations of 10 Be (16.1 ± 0.2 dpm kg -1 ) and 26 Al (42.6 ± 0.8 dpm kg -1 ) (see Table 7) in the stone fraction of Arpu Kuilpu are on the low end of the range of 16-25 dpm kg -1  \n( 10 Be) and 40-85 dpm kg -1 ( 26 Al) predicted by the model of Leya and Masarik (2009), suggesting that Arpu Kuilpu's meteoroid was small with maximum radius of 10 cm ( Figure 10 ).  Unfortunately, this model did not provide production rates for objects smaller than 10 cm, though these concentrations of 10 Be, 26 Al and 36 Cl are consistent with irradiation at a depth of <1 cm in a 10 cm object ( Figure 10 1b1d).  The  very  low  shielding  conditions  are  also  supported  by  the  relatively  high 10 Be  and 26 Al concentrations in the metal phase and the low 10 Be(sto)/ 10 Be(met) and 26 Al(sto)/ 26 Al(met) ratios of 2.9 and 9.9, respectively ( Table 7 ). These ratios are strongly dependent on shielding conditions (Nagai et al. 1990), with 10 Be(sto)/ 10 Be(met) increasing from values of ~3 in small chondrites to values of 5-13 in large chondrites, like FRO 90174 and Gold Basin (Welten et al. 2001; 2003). The 26 Al(sto)/ 26 Al(met) ratios show a range of 9-70 for the same chondrites. The values found in Arpu Kuilpu are among the lowest  values  reported  in  ordinary  chondrites,  similar  to  those  found  in  several  small  Antarctic  Hchondrites from the Frontier Mountain (FRO) icefield (Welten et al. 2001), including FRO 90037 (13.1 g)  and  90151  (33.6  g).  These  small  H-chondrites  also  had  very  high 22 Ne/ 21 Ne  ratios  of  1.27-1.32, similar to Arpu Kuilpu (1.28, see Table 9) . Such little shielding appears unlikely, as the outer >1 cm of the meteoroid is often lost during atmospheric ablation. However, since fragmentation was observed during the fireball event, it is quite possible that the meteorite came from a location close to the surface of the meteoroid, and survived to the ground, experiencing non-uniform ablation. Wieler et al. (2016) and Roth et al. (2017) have shown that SCR-derived Ne can commonly be observed in small ordinary chondrites and martian meteorites. An alternative approach to calculating the CRE age, which does not rely on the 22 Ne/ 21 Ne ratio, is to use the correlation between the 3 He, 21 Ne, and 38 Ar production rates as well  as  the  bulk 26 Al  production  rate  from  the  Leya  and  Masarik  (2009)  model  albeit  only  for meteoroids with radii ≥ 10 cm. Arpu Kuilpu's bulk 26 Al concentration of 37.2 dpm kg -1 is just within the  35-70  dpm  kg -1 range  found  in  this  model. Assuming  that  these  correlations  can  be  extended  to slightly  smaller  objects  with  ~5  cm  radius,  we  can  estimate 3 He, 21 Ne and 38 Ar production rates (in units of 10 -8 cm 3 STP/g/Ma) of 1.40, 0.176 and 0.035, respectively (note that these differ from those presented in Table 11, which used the modified model from Leya and Masarik (2009) extended to radii ≤ 10  cm  (Wieler  et  al.  2016)  and 22 Ne/ 21 Ne  ratios).  Using  the  cosmogenic 3 He, 21 Ne  and 38 Ar concentrations from Table 11 , this approach yields CRE ages of 6.2, 5.5 and 5.7 Ma, with an average value of 5.8 ± 0.6 Ma (based on an uncertainty of ~10% for the production rate calculations).  \nThis slight discrepancy in results between the noble gas only-informed model for small radii ≤ 10 cm (Wieler et al. 2016; 1 cm radius, <1 cm burial depth, ~7-9 Ma CRE age), and the 26 Al-informed Leya and Masarik (2009) approach using a model for radii ≥ 10 cm, extending it to ≤ 10 cm (adopting a 5-10 cm radius (based on gamma-ray spectrometry and short-lived radionuclides), <1 cm burial depth, ~6  Ma  CRE  age),  could  be  explained  in  two  ways:  sample  heterogeneity  and  model  uncertainty. Although  the  aliquots  for  the AMS,  noble  gas,  and  ICP-MS  analyses  all  originated  from  the  same physical  location,  approximately  ~0.5  cm  within  the  meteorite,  they  sometimes  show  minor,  yet noticeable deviation from each other and from typical H chondrite elemental concentrations. The ICPMS results, for instance, show an enrichment in trace siderophile elements which we attribute to an embedded refractory siderophile nugget ( Figure 4; Table 4 ). While the noble gas concentrations for the two aliquots measured (AKS and AKL) are close to one another, they often do not agree within error ( Table 9 ). Considering these aliquot-to-aliquot variations, and model uncertainties in both Wieler et  al.  (2016),  and  Leya  and  Masarik  (2009),  particularly  concerning  the  covered  meteoroid  size,  we assert these differences to be at the edge of our ability to infer the exact meteoroid history, and that future work may be needed to supplant or expand on existing models to comprehensively extend our understanding of CRE to very small (<10 cm) meteoroids and their surviving meteorites.  \nCombining these methods and their insights, we conclude that Arpu Kuilpu came from a small (<5  cm)  meteoroid,  very  near  to  its  surface  (<1  cm),  and  that  its  meteoroid  spent  ~6-8  Ma  in interplanetary space, separate from its contemporary asteroidal source body.  \nFigure 10. (a)  Comparison of the measured concentrations of 10 Be and 26 Al in the stone fraction of Arpu Kuilpu with calculated 10 Be and 26 Al production rates in the stone fraction of ordinary chondrites with radii of 10-100 cm. Panels (b-d) shows a comparison of the measured concentrations of 10 Be (b) 26 Al (c) and 36 Cl (d) in the stone fraction of Arpu Kuilpu with calculated depth profiles in the stone fraction of H-chondrites with radii of 10-30 cm. All calculations are based on the model of Leya and Masarik (2009).  \n<!-- image -->", 'Relation to Other Orbital Meteorites': "Considering the 53 other meteorites with associated orbits that have been recovered so far (at the time of this writing; Meier, 2017), the equilibrated H chondrites (H4s, H5s, and H6s) account for more than 30% (excluding multi-lithological falls), to which we will compare Arpu Kuilpu based on two main criteria: meteoroid orbit and CRE age ( Table 12) . We would also like to note that although the  H5/6  chondrites Al-Khadhaf  (MB 112; Gattacceca  et al., 2024) and Santa Filomena (Tosi et al., 2023) are both falls with known orbits, their CRE ages and probable source resonances are currently unknown, therefore we did not include them in our comparisons to Arpu Kuilpu. For likeness in orbital parameters, Ejby (Spurný et al. 2017) and Košice (Borovička et al. 2013) are the closest matches as they  both  have  a  high  probability  of  being  sourced  from  a  JFC  orbit  (although  with  relatively  high associated uncertainties), with Hamburg (Brown et al. 2019), then Murrili (Sansom et al. 2020) being next closest with Tisserand parameters near the border of being considered a JFC orbit. Interestingly, the CRE ages of Murrili (7 ± 1 Myr; Anderson et al. 2021) and Košice (5 -7 Myr; Povinec et al. 2015) are  similar  to Arpu  Kuilpu's  ~6 -8  Myr,  falling  within  the  broad  peak  of  6-8  Myr  for  H5  chondrites identified by Marti and Graf (1992). Although the Lost City and Morávka meteorites also have CRE ages falling into this broad peak (Bogard et al. 1971; Borovička et al. 2003b), their orbits are distinctly dissimilar, originating from the inner main belt, on the other side of the 3:1 mean motion resonance with Jupiter (McCrosky et al. 1971; Borovička et al. 2003a). Therefore, at first assessment, the most likely  orbital  meteoritic  sibling  to Arpu  Kuilpu  is  Košice,  since  it  has  the  same  CRE  age  and  orbit, within errors (which are comparatively high for the latter).  \nThough to properly compare Arpu Kuilpu to other orbital H chondrites, we must also consider how  orbits  can  evolve  over  time.  Although  the  semi  major  axes  of  most  small  meteoroids  change  \ngradually  over  many  orbital  periods,  due  to  the  Yarkovsky  effect  (Bottke  et  al.,  2001),  eventually wandering into a mean motion resonance with Jupiter which then increases its eccentricity ultimately causing  a  collision  with  one  of  the  inner  planets,  the  work  by  Shober  et  al.  (2020a;  2020b) demonstrates an additional mechanism for orbital evolution. They show how a meteoroid with a nearEarth orbit (a < 2 AU) can have a close encounter with an inner planet, immediately altering its path to a JFC-like orbit. This is further supported by a later study (Shober et al. 2021) that shows how most objects in the cm-m size range on JFC orbits are asteroidal in nature, and not composed of volatile-rich material (originating from trans-Neptunian space (Nesvorný et al. 2010; Fernández and Sosa, 2015)) typical of dust and km sized objects existing on similar orbits. Using this mechanism, we can speculate that Arpu Kuilpu, Košice, Murrili, and Lost City were all liberated from the same source body in the same  ejection  event  (~68  Ma)  in  the  inner  solar  system,  but  that  only  Arpu  Kuilpu  and  Košice underwent close encounters to transfer into a JFC-like orbit. Although Morávka has a similar CRE age to Arpu Kuilpu, its high inclination (i = 32; Table 12 ),  especially  compared to the other H5's listed here, make a close orbital link unlikely. For Ejby and Hamburg, it is possible that they were ejected at different  times,  from  either  the  same  or  different  source  bodies  in  the  inner  solar  system,  then  also independently experienced this  change  in  orbit,  which  eventually  delivered  them  to  Earth.  It  is  also entirely  possible  that  none  of  these  rocks  are  related  to  each  other  and  that  each  one  represents  a discrete  source  body  within  the  solar  system.  Only  as  more  orbital  meteorites  are  collected  and analyzed, can we more confidently infer about the nature of contemporary H chondrite source bodies.  \nTable 12. Other orbital meteorites that may be related to Arpu Kuilpu, based on orbital parameters and CRE age.  \na: Shober et al. (2022); b: Borovička et al. (2013); c: Povinec et al. (2015); d: Borovička et al. (2003a); e: Borovička et al. (2003b); f: Ceplecha and ReVelle , (2005); g: McCrosky et al. (1971); h: Bogard et al. (1971); i: Brown et al. (2019); j: Heck et al. (2020); k: Sansom et al. (2020); l: Anderson et al. (2021); m: Spurný et al. (2017); n: Haack et al. (2019);", 'CONCLUSIONS': "The Arpu Kuilpu orbital meteorite is a minimally-shocked, lightly-weathered, unbrecciated, H5 chondrite that was delivered to Earth on a JFC-like orbit. The very minor impact-related shock pressure it  experienced  occurred  very  early  in  the  solar  system's  history.  It  was  likely  separated  from  its contemporary, asteroidal source body approximately 6-8 Ma ago, and may be related to other orbital H chondrites,  with  Košice  being  the  closest  match  when  considering  prior  orbits  and  CRE  ages  (see Discussion). Combining Arpu Kuilpu's asteroidal composition with its JFC -like orbit prior to impact further confirms the observation that small meteoroids (cm-m size) on JFC orbits can originate from the asteroid belt. Below ( Table 13 ) we list the major features of this meteorite, and the methods used to determine them.  \nTable 13. The main features of the Arpu Kuilpu meteorite.", 'ACKNOWLEDGMENTS': "We would like to thank the Maralinga Tjarutja community for permission to search on their land, as well  as  providing  the  name  for  this  meteorite.  We  also  thank  C. Alexander  and  J.  Bridges  for  their careful  and  constructive  reviews. 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