Lunar impact flashes provide a direct means of estimating the flux of centimetre-sized meteoroids impacting the lunar surface. However, 25-60 frames per second imaging typical of most monitoring programs limit the ability to resolve the rapid temporal evolution of the impact process, while the integration of Earthshine background restricts the detection of faint flashes. In this work, we present high-speed observations of lunar impact flashes captured at 200 and 250 FPS using the Zadko Telescope in Western Australia. We resolve the light curves of four confirmed events, revealing complex morphologies, some of which are not well modelled by simple exponential decays. One event was simultaneously detected by a second observer using a 50 FPS system, revealing a significantly faster brightness drop in the high-speed data that cannot be explained by spectral differences alone, indicating temporal integration of the vapour plume and subsequent ejecta. Our data also indicates that the initial flash intensity (representing the vapour plume) exhibits significantly less variance across events than the total luminous energy. Furthermore, we found no statistical correlation between the initial luminous energy and the total integrated energy of the flashes in this data, suggesting that the physical mechanism driving the initial vapour expansion may be physically decoupled from the longer-duration glow driven by the cooling ejecta. High temporal resolution combined with high sensitivity are therefore essential for accurately characterising the physical properties of the impactor and distinguishing the initial vapour plume from the subsequent incandescent cooling phase, although a significantly larger dataset is required to definitively constrain these mechanisms.

Deployable solar arrays increase spacecraft capabilities by providing a greater power generation capacity than can be achieved by the available surface area of the chassis. On smaller form factors such as 1U cube satellites, this benefit is often overshadowed by the typical increase in mass, envelope, and complexity. To address this, a rigid-flex PCB-based system actuated by nickel-titanium shape memory alloy is presented, which demonstrates high power generation density and meets the stringent envelope requirements of a 1U cube satellite without significantly increasing design and manufacturing complexity. By leveraging the PCB manufacturing industry and the benefits of compliant mechanisms, the deployable solar array design achieves a high power-to-weight and power-to-stowed-volume ratio while requiring minimal additional assembly over body-mounted solar panels. This work presents the design, assembly, and verification of the rigid-flex PCB-based solar array concept, showing that it meets the requirements typical of cube satellites deployed from the International Space Station. These solar arrays were flight-tested on the Binar Space Program's second mission, consisting of three 1U cube satellites (Binar-2, Binar-3, and Binar-4), and the results obtained are presented and inform refinements to the design and assembly. This system has been demonstrated to be an effective solution increasing the power generation of many 1U cube satellite platforms, and represents the first flight-test of a rigid-flex PCB-based deployable solar array.

CubeSat and small satellite resistojet heat exchanger designs are based on conventional concepts that have been used since the 1960s, being primarily limited to helical or twisted tape heat exchangers. The design flexibility enabled by new additive manufacturing technologies is yet to be properly harnessed. This study introduces a novel resistojet concept that incorporates a highly miniaturized lattice structure as the heat exchanger. A conjugate heat transfer analysis determined that the lattice with a diamond unit cell had superior thermal performance compared to the same lattice with a gyroid unit cell and increased the heat transfer rate by up to 11% compared to a helical heat exchanger of the same volume. Performance testing of the prototype thruster with integral diamond lattice indicated that specific impulses of up to 94 s were possible with a 30-Watt heater using nitrous oxide as the propellant. The prototype thruster weighed only 22 g and demonstrated a 67% reduction in the power required to achieve the same specific impulse as previous nitrous oxide resistojets designed for the small satellite platform. The development of highly miniaturized latticed resistojets is shown to be feasible and highly attractive for CubeSats, where mass and power are of the utmost importance.

Understanding the tension between the dynamical and physical characteristics of solar system debris has been a goal of astronomers and planetary scientists for a long time. This study considered a large (>1400) dataset of orbits gathered from six years of fireball observations observed by the Desert Fireball Network. We focused on the meteoroids we detected originating from short-period comet orbits (2 < TJ < 3). We examined how durable they were as they went through the atmosphere and their orbital evolution over the previous ten thousand years. Our results show that almost all of the meteoroids we see in this size range are sourced from the main belt, not the Jupiter-family comet population. The fact that we do not see these objects shows that genetically cometary material in the centimeter size range does not last long in the inner solar system. Even when meteor shower debris is taken into account, the majority of material at centimeter to meter-scales on comet-like orbits is from the main belt.We worked with inclusive criteria to be considered cometary in origin. To be classified as cometary, a meteoroid must be at least a Type II according to the PE criterion and have a >50% probability of originating from an unstable orbit over the previous 10 kyrs. Of the 50 sporadic comet-like fireballs observed by the DFN since 2014, only 2 fulfilled this criterion (figure below). Using a Markov Chain Monte Carlo to draw samples from the posterior distribution, we found that sporadic JFC-like meteoroids in NEO space is 94.2% ± 3.2% from the main belt when considering an uninformed prior. This demonstrates that cometary debris has physical lifetimes in near-Earth space less than the decoherence lifetimes for a stream (

Imaging and all-sky brightness sensors are common instruments used to acquire light curve data of both fireballs and meteors during their bright flight. This data allows modelling of the ablation process using a photometric model which can be calibrated using light sources with known properties such as stars. The imaging systems typically consist of long exposure images which are occulted periodically by shutters, or video cameras[1][2][3]. The light curve sampling rates of these imaging systems is usually between 10Hz and 30Hz. However, they have limited dynamic range causing them to saturate during bright fireballs, and do not have the temporal resolution to identify brief flaring events which limits their use in photometric modelling.To capture non-saturated bright fireballs at a higher temporal resolution, all-sky brightness sensors using photomultiplier tubes have been deployed to collect data with sampling rates between 500Hz and 5000Hz [4]. Photodiodes have also been explored as a low cost sensor for measuring all-sky brightness at similar sampling rates [5][6][7]. However calibration of the data from these sensors requires external calibrated photometric data acquired from imagery [8]. Operating photomultiplier tubes also requires special design considerations such as protection from the sun during the day, and high voltage power supply designs which can make them difficult to deploy and operate efficiently [9]. To address some of the limitations of these instruments, a low cost, all-sky, high frame rate camera system has been developed that captures 12 bit data at 470 frames per second, producing light curves of fireballs and meteors that can be directly photometrically calibrated using stars. The fast exposure period that this frame rate enables and high data bit depth allows the system to image brighter fireballs compared to other video camera systems. The first results show promise as an instrumentation method to produce high temporal resolution photometric data of these events using standard computing hardware, off-the-shelf cameras, and simple deployment.[1] R. M. Howie, J. Paxman, P. A. Bland, M. C. Towner, E. K. Sansom, and H. A. R. Devillepoix, ‘Submillisecond fireball timing using de Bruijn timecodes’, Meteoritics & Planetary Science, vol. 52, no. 8, pp. 1669–1682, 2017, doi: 10.1111/maps.12878.[2] D. Vida et al., ‘The Global Meteor Network - Methodology and first results’, Monthly Notices of the Royal Astronomical Society, vol. 506, pp. 5046–5074, Oct. 2021, doi: 10.1093/mnras/stab2008.[3] F. Colas et al., ‘FRIPON: a worldwide network to track incoming meteoroids’, A&A, vol. 644, p. A53, Dec. 2020, doi: 10.1051/0004-6361/202038649.[4] P. Spurný, J. Borovička, G. Baumgarten, H. Haack, D. Heinlein, and A. N. Sørensen, ‘Atmospheric trajectory and heliocentric orbit of the Ejby meteorite fall in Denmark on February 6, 2016’, Planetary and Space Science, vol. 143, pp. 192–198, Sep. 2017, doi: 10.1016/j.pss.2016.11.010.[5] D. Vida, R. Turčinov, D. Šegon, and E. Silađi, Low-cost meteor radiometer. 2015, p. 180. Accessed: May 15, 2024. [Online]. Available: https://ui.adsabs.harvard.edu/abs/2015pimo.conf..180V[6] S. R. G. Buchan, R. M. Howie, J. Paxman, and H. A. R. Devillepoix, Developing a Cost-Effective Radiometer for Fireball Light Curves. eprint: arXiv:1907.12807, 2019, pp. 123–126. doi: 10.48550/arXiv.1907.12807.[7] J.-L. Rault, A little tour across the wonderful realm of meteor radiometry. eprint: arXiv:1911.04290, 2020, pp. 112–117. doi: 10.48550/arXiv.1911.04290.[8] P. Spurný, J. Borovička, and L. Shrbený, ‘The Žďár nad Sázavou meteorite fall: Fireball trajectory, photometry, dynamics, fragmentation, orbit, and meteorite recovery’, Meteoritics & Planetary Science, vol. 55, no. 2, pp. 376–401, 2020, doi: 10.1111/maps.13444.[9] R. M. Howie et al., ‘How to build a continental scale fireball camera network’, Exp Astron, vol. 43, no. 3, pp. 237–266, Jun. 2017, doi: 10.1007/s10686-017-9532-7.

Near-Earth objects (NEOs) are typically fiercely monitored due to the inherent danger of their close encounters. Encounters with more massive objects at distances of a few lunar distances (LD) are relatively commonplace. However, fireball and meteor observation networks from around the world have witnessed ‘grazing’ events occur on several occasions [1, 2, 3, 4, 5]. Grazing events are characterized by their low impact angle and their possible re-entry into interplanetary space. These fireballs display how there are likely many smaller objects, that cannot be detected telescopically, that encounter the Earth all the time. Close encounters can quickly scatter meteoroids into drastically distinct orbits. This process is exemplified by the grazing fireball event detected by the Desert Fireball Network (DFN) in 2017 [5]. During this event, a ≥ 0.3 m object grazed the atmosphere coming from an Apollo-type orbit and exited with a JFC-like orbit. In order to characterize the population of objects in this small size range, we utilized the data collected by the Desert Fireball Network (DFN). The DFN is a continental-scale photographic fireball monitoring network covering over 2.5 million square kilometers of the Australian outback. The Earth’s close encounter flux in the 0.01-100 kg range was estimated using the impact flux observed by the DFN. To do this, several inherent biases had to be taken into account. Some of these biases include: limiting sensitivity of the fireball observatories, seasonal and diurnal variations in the flux, and gravitational focusing. These biases were all taken into consideration. The size-range analyzed in the DFN dataset was cutoff at small-sizes in order to remove the excess of fast, small meteoroids. Whereas, the diurnal and seasonal effects on the average flux of the DFN were considered negligible [6]. Most importantly, gravitational focusing must be corrected for or the flux of slower asteroidal material would be overestimated. The flux enhancement factor was accounted for using the global average enhancement determined by Opik [7], and scaled accordingly based on close encounter ¨ distance. In total, the close encounter population was modeled using 2.3 million test particles. The close encounter simulations, based on the DFN orbital dataset, demonstrated a significant population of close encounters at the centimeter/meter scale. Most of these bodies are negligibly affected during their close encounters; however, many experience considerable orbital changes (Fig. 1). Since the most likely objects to encounter the Earth are those with orbits more similar to the Earth, many close encounters come from asteroid-like (TJ > 3) objects. During the encounter, objects either gain or lose energy resulting in an inverse change to the objects TJ value. In total there appears to be a net gain of objects flung from asteroidal to JFC-like orbits. These encounters are considerably rare (about 0.16% of the total flux within 1.5 LD); however, considering the vast number of objects predicted to have close encounters at these small sizes, the size of this scattered population is not insignificant.References: [1] Z Ceplecha. In: Bull. Astron. Inst. Czechoslov. 30 (1979), pp. 349–356. [2] J Borovicka and Z Ceplecha. In: A&A 257 (1992), pp. 323–328. [3] D. O. Revelle, R. W. Whitaker, and W. T. Armstrong. In: vol. 3116. 1997, pp. 156–167. [4] J.M. Madiedo et al. In: MNRAS 460.1 (2016), pp. 917–922. [5] Patrick M Shober et al. “Where Did They Come From, Where Did They Go: Grazing Fireballs”. In: The Astronomical Journal 159.5 (2020), p. 191. [6] I. Halliday and A.A. Griffin. In: Meteoritics 17.1 (1982), pp. 31–46. [7] E.J. Opik. ¨ In: Proc. R. Ir. Acad. 1951, pp. 165–199.

On February 28, 2021, a fireball dropped similar to 0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (similar to 13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (similar to 0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s-1). A near-catastrophic fragmentation at similar to 0.07 MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region similar to 0.08 Myr ago and it never had a perihelion distance smaller than similar to 0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (similar to 0.5 AU) and were heated to at least 100 K higher temperatures.

The Desert Fireball Network is a fireball observing network which stretches across the southern part of the Australian continent. To date, it has over 50 cameras, covering an area of approximately 2.5m km2. Its purpose is to observe and triangulate fireballs, calculate trajectories for incoming meteorites. The camera network has been operational in digital form since 2012, and to date as captured approximately 1.5PTB of data, primarily all sky images. We present an overview of the DFN results to date, detailing the dataset of approximately 1500 orbits, and over 30 possible candidate meteorite falls, and describe the most recent results. In particular, the team have recently recovered two candidate meteorites; one from the Nullarbor and one from the Simpson Desert in South Australia. The comparison the stories of these recoveries illustrate the typical issues of searching meteorite searching, and of verifying the meteorite’s provenance, and possible origin of the rocks is interesting to compare.

On June 1, 2019, just before 7:30 p.m. local time, the Desert Fireball Network (DFN) detected a -9.3 magnitude fireball over South Australia near the Western Australia border. The event was observed by six fireball observatories, and lasted for 5 s. One station was nearly directly underneath the trajectory, greatly constraining the trajectory solution. This trajectory's backward numerical integrations indicate that the object originated from the outer main belt with a semimajor axis of 2.75 au. A light curve was also extracted and showed that the body experienced very little fragmentation during its atmospheric passage. A search campaign was conducted with several DFN team members and other volunteers. One 42 g fragment was recovered within the predicted fall area based on the dark flight model. Based on measurements of short-lived radionuclides, the fragment was confirmed to be a fresh fall. The meteorite, Arpu Kuilpu, has been classified as an H5 ordinary chondrite. This marks the fifth fall recovered in Australia by the DFN, and the smallest meteoroid (similar or equal to 2 kg) to ever survive entry and be recovered as a meteorite.

On June 19, 2020 at 20:05:07 UTC, a fireball lasting 5.5s was observed above Western Australia by three Desert Fireball Network observatories. The meteoroid entered the atmosphere with a speed of 14.00 +/- 0.17 km s(-1) and followed a 58 degrees slope trajectory from a height of 75 km down to 18.6 km. Despite the poor angle of triangulated planes between observatories (29 degrees) and the large distance from the observatories, a well-constrained kilo-size main mass was predicted to have fallen just south of Madura in Western Australia. However, the search area was predicted to be large due to the trajectory uncertainties. Fortunately, the rock was rapidly recovered along the access track during a reconnaissance trip. The 1.072 kg meteorite called Madura Cave was classified as an L5 ordinary chondrite. The calculated orbit is of Aten type (mostly contained within the Earth's orbit), only the second time a meteorite was observed on such an orbit, after Bunburra Rockhole. Dynamical modeling shows that Madura Cave has been in near-Earth space for a very long time. The dynamical lifetime in near-Earth space for the progenitor meteoroid is predicted to be similar to 87 Myr. This peculiar orbit also points to a delivery from the main asteroid belt via the nu 6 resonance, and therefore an origin in the inner belt. This result contributes to drawing a picture for the existence of a present-day L chondrite parent body in the inner belt.

On 2020 December 5 at 17:28 UTC, the Japan Aerospace Exploration Agency's Hayabusa-2 sample return capsule came back to the Earth. It re-entered the atmosphere over South Australia, visible for 53 seconds as a fireball from near the Northern Territory border toward Woomera where it landed in the the Woomera military test range. A scientific observation campaign was planned to observe the optical, seismo-acoustic, radio, and high energy particle phenomena associated with the entry of an interplanetary object. A multi-institutional collaboration between Australian and Japanese universities resulted in the deployment of 49 instruments, with a further 13 permanent observation sites. The campaign successfully recorded optical, seismo-acoustic, and spectral data for this event which will allow an in-depth analysis of the effects produced by interplanetary objects impacting the Earth's atmosphere. This will allow future comparison and insights to be made with natural meteoroid objects.

Fireball networks are used to recover meteorites, with the context of orbits. Observations from these networks cover the bright flight, where the meteoroid is luminescent, but to recover a fallen meteorite, these observations must often be predicted forward in time to the ground to estimate an impact position. This dark-flight modeling is deceptively simple, but there is hidden complexity covering the precise interactions between the meteorite and the (usually active) atmosphere. We describe the method and approach used by the Desert Fireball Network, detailing the issues we have addressed, and the impact that factors such as shape, mass, and density have on the predicted fall position. We illustrate this with a case study of Murrili meteorite fall that occurred into Lake Eyre-Kati Thanda in 2015. The fall was very well observed from multiple viewpoints, and the trajectory was steep, with a low-altitude endpoint, such that the dark flight was relatively short. Murrili is 1.68 kg with a typical ordinary chondrite density but with a somewhat flattened shape compared to a sphere, such that there are discrepancies between sphere-based predictions and the actual recovery location. It is notable that even in this relatively idealized dark-flight scenario, modeling using spherically shaped projectiles resulted in a significant distance between predicted fall position and recovered meteorite.

On Aug 22, 2016, a bright fireball was observed by the Desert Fireball Network in South Australia. Its pre-atmosphere orbit suggests it was temporarily captured by the Earth-Moon system before impact. A search was conducted two years after the fall, and a meteorite was found after 6 days of searching. The meteorite appeared relatively fresh, had a mass consistent with fireball observation predictions, and was at the predicted location within uncertainties. However, the meteorite did show some weathering and lacked short-lived radionuclides (^58Co, ^54Mn). A terrestrial age based on cosmogenic ^14C dating was determined; the meteorite has been on the Earth's surface for 3.2±1.3 kyr, ruling out it being connected to the 2016 fireball. Using an upper limit on the pleistieocene terrain age and the total searched area, we find that the contamination probability from another fall is <2%. Thus, the retrieval of the "wrong" meteorite is at odds with the contamination statistics. This is a key example to show that fireball-meteorite pairings should be carefully verified.

Murrili, the third meteorite recovered by the Desert Fireball Network, is analyzed using mineralogy, oxygen isotopes, bulk chemistry, physical properties, noble gases, and cosmogenic radionuclides. The modal mineralogy, bulk chemistry, magnetic susceptibility, physical properties, and oxygen isotopes of Murrili point to it being an H5 ordinary chondrite. It is heterogeneously shocked (S2–S5), depending on the method used to determine it, although Murrili is not obviously brecciated in texture. Cosmogenic radionuclides yield a cosmic ray exposure age of 6–8 Ma, and a pre‐atmospheric meteoroid size of 15–20 cm in radius. Murrili’s fall and subsequent month‐long embedment into the salt lake Kati Thanda significantly altered the whole rock, evident in its Mössbauer spectra, and visual inspection of cut sections. Murrili may have experienced minor, but subsequent, impacts after its formation 4475.3 ± 2.3 Ma, which left it heterogeneously shocked.

The Desert Fireball Network observed a significant outburst of fireballs belonging to the Southern Taurid Complex of meteor showers between October 27 and November 17, 2015. At the same time, the Cameras for Allsky Meteor Surveillance project detected a distinct population of smaller meteors belonging to the irregular IAU shower #628, the s-Taurids. While this returning outburst was predicted and observed in previous work, the reason for this stream is not yet understood. 2015 was the first year that the stream was precisely observed, providing an opportunity to better understand its nature. We analyse the orbital elements of stream members, and establish a size frequency distribution from millimetre to metre size range. The stream is highly stratified with a large change of entry speed along Earth's orbit. We confirm that the meteoroids have orbital periods near the 7:2 mean-motion resonance with Jupiter. The mass distribution of this population is dominated by larger meteoroids, unlike that for the regular Southern Taurid shower. The distribution index is consistent with a gentle collisional fragmentation of weak material. A population of metre-sized objects is identified from satellite observations at a rate consistent with a continuation of the size-frequency distribution established at centimetre size. The observed change of longitude of perihelion among the s-Taurids points to recent (a few centuries ago) activity from fragmentation involving surviving asteroid 2015TX24. This supports a model for the Taurid Complex showers that involves an ongoing fragmentation cascade of comet 2P/Encke siblings following a breakup some 20,000 years ago.

The Desert Fireball Network is the most extensive photographic fireball observatory in the world, covering over 2.5 million square kilometers. The data included are from fireball observations between 2014-2020 of objects originating from sporadic (non-shower associated) comet-like orbits. In total, there were 50 fireball events with those characteristics. Please reference Shober et al. (2021) for more information.

Jupiter-family comets (JFCs) contribute a significant amount of debris to near-Earth space. However, telescopic observations of these objects seem to suggest that they have short physical lifetimes. If this is true, the material generated will also be short-lived, but fireball observation networks still detect material on cometary orbits. This study examines centimeter-to-meter-scale sporadic meteoroids detected by the Desert Fireball Network from 2014 to 2020 originating from JFC-like orbits. Analyzing each event’s dynamic history and physical characteristics, we confidently determined whether they originated from the main asteroid belt or the trans-Neptunian region. Our results indicate that <4% of sporadic meteoroids on JFC-like orbits are genetically cometary. This observation is statistically significant and shows that cometary material is too friable to survive in near-Earth space. Even when considering shower contributions, meteoroids on JFC-like orbits are primarily from the main belt. Thus, the presence of genuine cometary meteorites in terrestrial collections is highly unlikely.