This work is dedicated to debias the Near-Earth Objects (NEO) population based on observations from the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescopes. We have applied similar methods used to develop the recently released NEO model generator (NEOMOD), once debiasing the NEO population using data from Catalina Sky Survey (CSS) G96 telescope. ATLAS is composed of four different telescopes. We first analyzed observational data from each of all four telescopes separately and later combined them. Our results highlight main differences between CSS and ATLAS, e.g., sky coverage and survey power at debiasing the NEO population. ATLAS has a much larger sky coverage than CSS, allowing it to find bright NEOs that would be constantly "hiding" from CSS. Consequently, ATLAS is more powerful than CSS at debiasing the NEO population for H $\lesssim$ 19. With its intrinsically greater sensitivity and emphasis on observing near opposition, CSS excels in the debiasing of smaller objects. ATLAS, as an all sky survey designed to find imminent hazardous objects, necessarily spends a significant fraction of time looking at places on the sky where objects do not appear, reducing its power for debiasing the population of small objects. We estimate a NEO population completeness of $\approx$ 88%$^{+3\%}_{-2\%}$ for H $<$ 17.75 and $\approx$ 36%$^{+1\%}_{-1\%}$ for H $<$ 22.25. Those numbers are similar to previous estimates (within error bars for H $<$ 17.75) from CSS, yet, around 3% and 8% smaller at their face values, respectively. We also confirm previous finding that the $\nu_6$ secular resonance is the main source of small and faint NEOs at H = 28, whereas the 3:1 mean motion resonance with Jupiter dominates for larger and brighter NEOs at H = 15.

The Vera C. Rubin Observatory is due to commence the 10-year Legacy Survey of Space and Time (LSST) at the end of 2025. To detect transient/variable sources and identify solar system objects (SSOs), the processing pipelines require templates of the static sky to perform difference imaging. During the first year of the LSST, templates must be generated as the survey progresses, otherwise SSOs cannot be discovered nightly. The incremental template generation strategy has not been finalized; therefore, we use the Metric Analysis Framework (MAF) and a simulation of the survey cadence (one_snap_v4.0_10yrs}) to explore template generation in Year 1. We have assessed the effects of generating templates over timescales of days-weeks, when at least four images of sufficient quality are available for $\geq90\%$ of the visit. We predict that SSO discoveries will begin $\sim$2-3 months after the start of the survey. We find that the ability of the LSST to discover SSOs in real-time is reduced in Year 1. This is especially true for detections in areas of the sky that receive fewer visits, such as the North Ecliptic Spur (NES), and in less commonly used filters, such as the $u$ and $g$-bands. The lack of templates in the NES dominates the loss of real-time SSO discoveries; across the whole sky the MAF Main-Belt asteroid (MBA) discovery metric decreases by up to $63\%$ compared to the baseline observing strategy, whereas the metric decreases by up to $79\%$ for MBAs in the NES alone.

We present GRSS , a small-body propagation and orbit determination library specifically designed for planetary defense applications. GRSS is an end-to-end, open-source software tool that begins with optical observations obtained from the Minor Planet Center and Gaia spacecraft, as well as radar observations from the Jet Propulsion Laboratory, and ends with reliable predictions about the trajectory of a small body in the solar system. The library is built on a C++11 orbit propagation core and provides additional orbit determination capability through a Python interface for ease of use. We conducted extensive validation for both of these components of the library by comparing them with the state-of-the-art operational software tools. We demonstrate the capabilities of GRSS by applying it to orbit propagation for (65803) Didymos and orbit determination for (29075) 1950 DA. We also used GRSS to calculate the keyholes for the 2135 close encounter of (101955) Bennu and determine the impact location for 2024 BX _1 and 2024 RW _1 . The library is designed to be modular and extensible, allowing for future addition of additional orbit filters and dynamical models. GRSS is publicly available on GitHub under a GPLv3 license and is intended to be a community resource for planetary science and planetary defense.

Small near-Earth asteroid 1998 KY26 has recently become an object of interest because it is the target of the Hayabusa2 & sharp; mission and because challenges in fitting its astrometric data have led to classifying it as a dark comet. Data acquired during the favorable apparition in 2024 helped significantly improve the physical characterization of 1998 KY26 but also led to increased orbit determination challenges. We develop a high-fidelity force model of solar radiation pressure and thermal emission of 1998 KY26 that accounts for a nonspherical shape of the asteroid and results in an excellent orbital fit. Thanks to its close ties to the physical properties of the asteroid, the model removes the degeneracy in the orientation of the rotation pole stemming from lightcurve analysis and constrains 1998 KY26's bulk density to 2.8-1.0+1.6 g cm-3 (90% confidence level), which is consistent with the asteroid's taxonomic type. Our model does not require the contribution of undetected cometary activity of 1998 KY26, which alleviates safety concerns for the Hayabusha2 & sharp; mission and has broader implications for the dark comet hypothesis.

Kinetic deflection is a planetary defense technique delivering spacecraft momentum to a small body to deviate its course from Earth. The deflection efficiency depends on the impactor and target. Among them, the contribution of global curvature was poorly understood. The ejecta plume created by NASA's Double Asteroid Redirection Test impact on its target asteroid, Dimorphos, exhibited an elliptical shape almost aligned along its north-south direction. Here, we identify that this elliptical ejecta plume resulted from the target's curvature, reducing the momentum transfer to 44 ± 10% along the orbit track compared to an equivalent impact on a flat target. We also find lower kinetic deflection of impacts on smaller near-Earth objects due to higher curvature. A solution to mitigate low deflection efficiency is to apply multiple low-energy impactors rather than a single high-energy impactor. Rapid reconnaissance to acquire a target's properties before deflection enables determining the proper locations and timing of impacts.

We present a new method for computing the state transition matrix of a nonlinear dynamical system. The proposed method does not require the implementation of complex partial derivatives or auto-differentiation of the dynamics, while removing the arbitrary choice of a perturbation step for traditional finite difference methods. We tested the new state transition matrices using three different applications: a simple two-body problem, a Mars atmospheric entry flight mechanics problem, and two future close encounters of the asteroid (101955) Bennu with the Earth. Results show that the unscented transform state transition matrices preserve symplecticity and perform just as well as the classical unscented transform. Furthermore, the new method can closely reproduce posterior distributions generated using Monte Carlo simulations, even in the presence of significant stiffness in the dynamics.

We characterize asteroid (16) Psyche using high-precision astrometry, including the recent Gaia Focused Product Release. The gravitational perturbations of Psyche on other asteroids can be observable in the case of mutual encounters. Using a least squares approach, we estimate the mass of Psyche by fitting astrometric data of asteroids that come within 0.05 au of Psyche. Combining the resulting individual estimates, we find GM = 1.601 +/- 0.017 km3 s-2. This result is robust against variations in the orbit determination setup and specific data set used. The volume and equivalent radius of Psyche are currently constrained by occultations and radar and optical imaging to (5.75 +/- 0.19) x 106 km3 and 111 - 0.5 + 2 km, respectively. Given the volume of Psyche, our mass estimate corresponds to a bulk density of 4172 +/- 145 kg m-3, which is compatible with an M-type taxonomic classification. Finally, the phase-dependent photocenter offset is visible in the residuals of Gaia astrometric observations of Psyche. This effect is consistent with the size of Psyche.

Abstract: Thermally driven fracture processes, such as thermal fatigue, have been hypothesized to drive rock breakdown and regolith production on asteroid surfaces [e.g., 1-7]. Thermal cycling induces mechanical stresses in rocks that drive the propagation of microcracks, which may grow into larger-scale features. This can drive the development of morphological signatures such as surface fracturing and disaggregation, and through-going fractures that split boulders apart. The nature and rate of boulder breakdown is controlled by rock composition, as well as the rotation period and solar distance of the body, suggesting its signature varies widely across the diverse asteroid population. Understanding how the process operates is critical to characterizing their surface properties and evolution.Images from the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) spacecraft of the surface of Bennu provide the opportunity to search for in situ evidence of thermal breakdown over a wide range of scales. Recent works by the authors [7-9] show observations of boulder morphologies consistent with terrestrial observations [e.g., 10] and models of fatigue-driven boulder exfoliation [e.g., 11], i.e., the flaking of thin layers or shells of material from boulder surfaces. Relating these observations to thermally induced stress fields in phyllosilicate boulders reveals that such features develop via the propagation of surface-parallel fractures during periods of day when boulder surfaces are heating. The magnitude of these stress fields ranges from ~0.3 to 3 MPa for boulders up to 6 m in diameter, which is comparable to the tensile strengths of terrestrial phyllosilicate rocks (e.g., serpentinite) and sufficient to drive subcritical crack growth (thermal fatigue). The thickness of resulting exfoliation layers predicted by the model ranges from ~1 mm to 10 cm, which is consistent with terrestrial observations of exfoliation cracks [10] and with the thicknesses of exfoliation layers observed on Bennu’s boulders [9].Further, we explore how boulder exfoliation may lead to the ejection of particles observed at Bennu’s surface [9] in an analogous manner to mobilization of rock fragments during large-scale, terrestrial dome exfoliation events [12]. We have observed particle ejection events from Bennu’s surface repeatedly since first entering orbit in January 2019. Observed particles range in size from

Kinetic deflection is a planetary defense technique that delivers spacecraft momentum to a small body to deviate its course from Earth. The deflection efficiency depends strongly on the impactor and target. Among them, the contribution of global curvature was poorly understood. The ejecta plume created by NASA's DART impact on its target asteroid, Dimorphos, exhibited an elliptical shape almost aligned along its north-south direction. Here, we identify that this elliptical ejecta plume resulted from the target’s curvature, reducing the momentum transfer to 44±10% along the orbit track compared to an equivalent impact on a flat target. We also find lower kinetic deflection of impacts on smaller Near-Earth objects (NEOs) due to higher curvature. A solution to mitigate low deflection efficiency is to apply multiple low-energy impactors rather than a single high-energy impactor. Rapid reconnaissance to acquire a target's properties before deflection enables determining the proper locations and timing of impacts.

The NASA Double Asteroid Redirection Test (DART) spacecraft impacted the secondary body of the binary asteroid (65803) Didymos on 2022 September 26 and altered its orbit about the primary body. Before the DART impact, we performed visible and mid-infrared observations to constrain the pre-impact thermophysical properties of the Didymos system and to model its Yarkovsky effect. Analysis of the photometric phase curve derives a Bond albedo of 0.07 ± 0.01, and a thermophysical analysis of the mid-infrared observations derives a thermal inertia of 320 ± 70 J m −2 K −1 s −1/2 and a thermal roughness of 40° ± 3° rms slope. These properties are compatible with the ranges derived for other S-type near-Earth asteroids. Model-to-measurement comparisons of the Yarkovsky orbital drift for Didymos derives a bulk density of 2750 ± 350 kg m −3 , which agrees with other independent measures based on the binary mutual orbit. This bulk density indicates that Didymos is spinning at or near its critical spin-limit at which self-gravity balances equatorial centrifugal forces. Furthermore, comparisons with the post-impact infrared observations presented in Rivkin et al. indicate no change in the thermal inertia of the Didymos system following the DART impact. Finally, orbital temperature simulations indicate that subsurface water ice is stable over geologic timescales in the polar regions if present. These findings will be investigated in more detail by the upcoming ESA Hera mission.

The capability to caracterize small bodies by stellar occultations has expanded enormously thanks to the Gaia mission, whose accurate astrometry has improved by order of magnitude the accuracy of star positions and proper motions, and asteroid orbits. More and more occultations by minor planets as small as 5-10~km in the Main Belt are reported by observers often equipped with mobile telescopes of modest size. Appropriate techniques to recover the absolute timing of the observed events and software tools that are now widely available permit to recover asteroid astrometry (relative to the star positions) with accuracies comparable to Gaia, especially at the smallest asteroid sizes.After some successful observations of occultations by Near Earth Asteroids such as Phaethon and Apophis, we took the challenge to push the limit at smaller sub-km NEAs. Several months before the impact by the DART probe on Dimorphos, satellite of (65803) Didymos, we established a networking activity of collaboration among amateur and professional astronomers, named ACROSS (Asteroid Collaborative Research via Occultation Systematic Survey), initially supported by the European Space Agency.One of the primary goals of ACROSS is to obtain very accurate astrometry over a few years, in order to evaluate the effect of the (September 2022) DART impact on the heliocentric orbit of Didymos. However, just a few months before the DART arrival to the target the uncertainty in the ephemeris was more than an order of magnitude larger than the size of Didymos, making predictions and telescope deployment practically not feasible.After a long work of astrometric reduction of available CCD images collected during the DART/Hera ground-based campaign (fully exploited for photometry but not for astrometry) and careful weighting of the observations, we were able to gradually converge to an exploitable orbit accuracy very close to the date of the impact. Following several failed attempts, the first successful event was observed just after the DART impact.This positive detection was followed by several others (19 in total), over 6 months, providing an astrometric accuracy comparable to the DART telemetry. At the end of the campaign astrometry by occultations was able to constrain the orbit at the same level as the use of the DART telemetry.However, the success of the observations was also enhanced by the detection in 4 events of occultations by the satellite Dimorphos. While their contribution to our knowledge about the position of Dimorphos along its orbit is not major at this stage, we found that the occultation signal, modulated by diffraction effects, can provide relevant information about its size and shape.The new ongoing campaign of stellar occultation in 2024 can thus provide an important contribution not only to constraint the dynamical properties of the Didymos system, but also to understand the post-impact properties of Dimorphos, before the arrival of Hera, including its shape. A first occultation in May 2024 proved the high quality of the orbit, resulting in the first positive of the new sequence. In this talk, we will discuss the results obtained in 2023 and present some preliminary results from the ongoing 2024 campaign.

J.W. McMahon1, A.S. French1, D.N. Brack1, J. Leonard2, J. Geeraert2, B. Page2, P. Antreasian2, K. Getzandanner3, D. Rowlands3, E. Mazarico3, J. Small3, M. Moreau3, S. Chesley4, D. Farnocchia4, Y. Takahashi4, M. Hirabayashi5, P. Sanchez6, O. Barnouin7, S. Van wal8, M. Daly9, R.W. Gaskell10, E. Palmer10, J. Weirich10, C.L. Johnson10,11, M.M. Al Asad11, K. Walsh12, R. Ballouz13, E. Jawin14, M.C. Nolan13, D. S. Lauretta13 and the OSIRIS-REx Team. 1Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder (scheeres@colorado.edu), 2KinetX, Simi Valley, California, 3Goddard Space Flight Center, 4Jet Propulsion Laboratory, Pasadena, California, 5Auburn University, 6Colorado Center for Astrodynamics Research, University of Colorado Boulder, 7JHU Applied Physics Laboratory, 8ISAS/JAXA, 9York University, Toronto, Canada, 10Planetary Science Institute, Tucson, Arizona, 11Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, 12SwRI Boulder, Colorado, 13Lunar and Planetary Laboratory, University of Arizona, 14Smithsonian Institution

NASA's Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the natural satellite of (65803) Didymos, on 2022 September 26, as a first successful test of kinetic impactor technology for deflecting a potentially hazardous object in space. The experiment resulted in a small change to the dynamical state of the Didymos system consistent with expectations and Level 1 mission requirements. In the pre-encounter paper Richardson (2022), predictions were put forward regarding the pre- and post-impact dynamical state of the Didymos system. Here we assess these predictions, update preliminary findings published after the impact, report on new findings related to dynamics, and provide implications for ESA's Hera mission to Didymos, scheduled for launch in 2024 with arrival in late December 2026. Pre-encounter predictions tested to date are largely in line with observations, despite the unexpected, flattened appearance of Didymos compared to the radar model and the apparent pre-impact oblate shape of Dimorphos (with implications for the origin of the system that remain under investigation). New findings include that Dimorphos likely became prolate due to the impact and may have entered a tumbling rotation state. A possible detection of a post-impact transient secular decrease in the binary orbital period suggests possible dynamical coupling with persistent ejecta. Timescales for damping of any tumbling and clearing of any debris are uncertain. The largest uncertainty in the momentum transfer enhancement factor of the DART impact remains the mass of Dimorphos, which will be resolved by the Hera mission.

On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes (Thomas et al. 2023). Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite's orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from July 2022 to February 2023. We focus here on decomposable lightcurves, i.e. those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the post-impact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ~1 day after impact, and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days post-impact. This bulk photometric behavior was not well represented by an HG photometric model. An HG1G2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least March 2023. Its persistence implied ongoing escape of ejecta from the system many months after DART impact.

This study provides a pre-impact map of the albedo of the Double Asteroid Redirection Test (DART) target Dimorphos corrected for all the effects of viewing geometry, as well as an estimate of photometric roughness for the hemisphere imaged by DART. Other photometric properties are derived for the (65803) Didymos binary system based on DART and ground-based measurements obtained at JPL’s Table Mountain Observatory. The roughness, geometric albedo, phase curve and phase integral, and single particle phase function are typical of the S-family of asteroids. The major remaining uncertainty lies in the behavior of the phase curve below 7°. These results provide a baseline for comparison with Hera measurements, leading to an understanding of the quantitative effects of the kinetic impactor mitigation strategy.

NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1 σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β , resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.

Our previous model (NEOMOD2) for the orbital and absolute magnitude distribution of Near Earth Objects (NEOs) was calibrated on the Catalina Sky Survey observations between 2013 and 2022. Here we extend NEOMOD2 to include visible albedo information from the Wide-Field Infrared Survey Explorer. The debiased albedo distribution of NEOs can be approximated by the sum of two Rayleigh distributions with the scale parameters pV,dark≃0.03 and pV,bright≃0.17. We find evidence for smaller NEOs having (on average) higher albedos than larger NEOs; this is likely a consequence of the size-dependent sampling of different main belt sources. These inferences and the absolute magnitude distribution from NEOMOD2 are used to construct the debiased size distribution of NEOs. We estimate 830±60 NEOs with diameters D>1 km and 20,000±2,000 NEOs with D>140 m. The new model, NEOMOD3, is available via the NEOMOD Simulator – an easy-to-operate code that can be used to generate user-defined samples (orbits, sizes and albedos) from the model.

Catalina Sky Survey (CSS) is a major survey of Near-Earth Objects (NEOs). In a recent work, we used CSS observations from 2005–2012 to develop a new population model of NEOs (NEOMOD). CSS's G96 telescope was upgraded in 2016 and detected over 10,000 unique NEOs since then. Here we characterize the NEO detection efficiency of G96 and use G96's NEO detections from 2013–2022 to update NEOMOD. This resolves previous model inconsistencies related to the population of large NEOs. We estimate there are 936±29 NEOs with absolute magnitude H<17.75 (diameter D>1 km for the reference albedo pV=0.14) and semimajor axis a<4.2 au. The slope of the NEO size distribution for H=25–28 is found to be relatively shallow (cumulative index ≃2.6) and the number of H<28 NEOs (D>9 m for pV=0.14) is determined to be (1.20±0.04)×107, about 3 times lower than in Harris & Chodas (2021). Small NEOs have a different orbital distribution and higher impact probabilities than large NEOs. We estimate 0.034±0.002 impacts of H<28 NEOs on the Earth per year, which is near the low end of the impact flux range inferred from atmospheric bolide observations. Relative to a model where all NEOs are delivered directly from the main belt, the population of small NEOs detected by G96 shows an excess of low-eccentricity orbits with a≃1–1.6 au that appears to increase with H (≃30% excess for H=28). We suggest that the population of very small NEOs is boosted by tidal disruption of large NEOs during close encounters to the terrestrial planets. When the effect of tidal disruption is (approximately) accounted for in the model, we estimate 0.06±0.01 impacts of H<28 NEOs on the Earth per year, which is more in line with the bolide data. The impact probability of a H<22 (D>140 m for pV=0.14) object on the Earth in this millennium is estimated to be ≃4.5%.

On 2022 September 26 (UTC), NASA's Double Asteroid Redirection Test (DART) mission achieved a successful impact on Dimorphos, the secondary component of the near-Earth binary asteroid system (65803) Didymos. Subsequent ground-based observations suggest a significant reshaping of Dimorphos, with its equatorial axis ratio changing from 1.06 to ∼1.3. Here we report the effects of this reshaping event on Dimorphos's orbit and attitude. Given the reported reshaping magnitude, our mutual dynamics simulations show that approximately 125 s of the observed 33 minute orbit period change after the DART impact may have resulted from reshaping. This value, however, is sensitive to the precise values of Dimorphos's post-impact axis ratios and may vary by up to 2 times that amount, reaching approximately 250 s within the current uncertainty range. While the rotational state of the body is stable at the currently estimated axis ratios, even minor changes in these ratios or the introduction of shape asymmetry can render its attitude unstable. The perturbation to Dimorphos’s orbital and rotational state delivered by the impact directly, combined with any reshaping, leads to a strong possibility for a tumbling rotation state. To accurately determine the momentum enhancement factor ( β ) through measurements by the European Space Agency’s Hera spacecraft and to evaluate the effectiveness of the kinetic deflection technique for future planetary defense initiatives, the effects of reshaping should not be overlooked.

NASA’s OSIRIS-REx mission set out in September of 2016 to survey and sample the near-Earth asteroid (101955) Bennu. During observations of Bennu, mission scientists observed centimeter-scale pebbles ejecting off the surface of the asteroid [1]. Many of these particles have been observed to follow hyperbolic trajectories, and the intersection of the orbits of Bennu and Earth suggests the possibility of particle flux at Earth [2]. We simulate the evolution of the motion of particles ejected from Bennu with a focus on potential meteor activity at Earth. We developed a complex simulated environment that accounts for the most potent perturbing gravitational bodies and solar radiation forces that are applicable to our centimeter-scale size range [3]. We use REBOUND, an orbital integration API developed by Hanno, Rien and Tamayo [4], augmented with REBOUNDx, developed by Tamayo et al. [5], to include solar radiation pressure and Poynting-Robertson (PR) drag. Bennu is modeled as a massless object, though great care is spent ensuring Bennu’s orbital accuracy as the particles are integrated towards well-defined close approaches in the near future [6]. Contrary to most meteoroid stream evolution studies, our simulations release particles from Bennu at a regular cadence (600 grams per week) throughout its orbit to resemble mission observations. To test the accuracy of the model and integrator, we prepared test cases for expected behavior. Recreating examples of particle resonance traps due to PR drag confirmed the implementation of the non-gravitational forces. Observations of the particle stream circularization (Fig. 1) and associability over time were also indicative of expected behavior. Additionally, planetary bodies were initialized from a JPL ephemeris (DE 431) and continuously compared to these values as a reference. The modeled solar system maintained an accuracy of 10-1 to 101 arcseconds of mean anomaly for their expected positions, giving us confidence in our methods. Towards the main objective of observing Earth-particle interactions, limitations in processing power and time encourage us to run simulations at particle production rates lower than the mass loss observed at Bennu by a factor of 100. Earth-particle close approaches are recorded annually during simulations. These data are later converted into stream density estimates and Earth impact probabilities through analysis on the B-plane [7]. This formalism enables the calculation of the statistical likelihood of impact with Earth for all of the particles produced in the simulation over the 348 years of interest (1788–2135); the years over which Bennu’s position is best constrained [6]. Such results now inform our conclusions on zenith hourly rate flux measurements at Earth. This work will be of practical importance for professional and amateur astronomers searching for Bennuid meteors. While the exact particle production mechanisms are still open to debate, we are hopeful that this initial work can be generalized to encompass the entire near-Earth asteroid population. This work, together with additional particle ejection observations and analyses from the OSIRIS-REx mission, will pave the way to a full understanding of this astronomical phenomenon.References:[1] D.S. Lauretta and C.W. Hergenrother et al. (2019). Science 366, 1217-1227.[2] Q. Ye (2019) Notes of the AAS 3, 56.[3] P. Jenniskens et al. (2011) Icarus 216, 40-61, & cams.seti.org[4] H. Rien and S.F. Liu (2012) Astronomy & Astrophysics 537, A128.[5] Tamayo, Daniel, et al. (2020) Monthly Notices of the Royal Astronomical Society 491.2[6] S.R. Chesley et al. (2014) Icarus 235, 5-22[7] D. Farnocchia et al. (2019) Springer, Celestial Mechanics and Dynamical Astronomy.